1

/ X ^ U T-

JOURNAL

THE CHEMICAL SOCIETY.

TRANSACTIONS.

Committer of ^nblitatiou :

Horace T. Brown, LL.D., F.R.S.
A. W. Crossley, D.Sc, Ph.D., F.R.S.
H. B. Dixon, M.A., F.R.S.
Wyndham R. Dunstan, M.A., F.R,S.
M. 0. FoRSTER, D.Sc, Ph.D., F.R.S.
C. E. Groves, F.R.S.
J. T. Hewitt, M.A., D.Sc, Ph.D.

A. McKenzie, M.A., D.Sc, Ph.D.
R Meldola, F.R.S.
G. T. Morgan, D.Sc
A. Scott, M.A., D.Sc, F.R.,S.
Sir Edward Thorpe, C. B., LL.D.
F.R.S.

(ftbitor :
J. C. Cain, D.Sc, Ph.D.

^«b-f,Mtor :
A. J. Greenaway.

1909. Vol. XCV. Part II.

1-

V

LONDON:
GURNEY k JACKSON, 10, PATERNOSTER ROW

1909.

RicHAKf) Clay b Soss, Limited,

BREAD STREET HILL, E.C., ASD
BrNOAV, SUFFOLK.

\

i

J

VELOCITY OF DECOMI'O.SITION OF NITROGLYCEKIN JiY HEAT. Ti^l

A sample of tliis substance kept in a sealed tube was still alniost
white a week after preparation, thereafter the yellow colour slowly
became more marked. On opening the tube, sulphur, sulphur dioxide,
and jD-toluic anhydride were found to be present. The anhydride was
identified by a determination of its melting point and by conversion
into ^>-toluic acid.

(Jhemistky Department,
The Gla.sgow and West of Scotland Technical College,

CXXXIX. — The Velocity of Decornposition of Nitro-
glycerin by Heat. Part I.

By Egbert Eobertson, M.A., D.Sc, F.T.C.

Although the decomposition of nitrocellulose at temperatures
below the explosion point had long been a familiar phenomenon,
the mechanism by which the removal of nitrogen from the nitric
ester takes place was not investigated until recently, when
Dr. Will gave the results of his experiments in two papers :
*' Untersuchungen liber die Stabilitat von Nitrocellulose " (Erste
und Zweite Mitteilungeu aus der Zentralstelle fiir Wissenschaftlich-
technische Untersuchungen). In these papers the method of research
is founded on the measurement of the nitrogen evolved in unit
time from the nitrocellulose when this is heated at definite tem-
peratures under such conditions that the volatile products of
decomposition are continuously removed. From the results obtained
many important deductions are made, of which, perhaps, the
principal is that a normal or intrinsic decomposition is a funda-
mental property of cellulose nitric esters, among which is gun-
cotton. For a given temperature this normal decomposition is
characterised by a uniformity of evolution of nitrogen, on the one
hand, and by a certain minimum of evolution, depending on the
degree of nitration of the cellulose, on the other. Instability may
be detected by irregularity in decomposition, or- by a higher
coefficient of evolved nitrogen than is found with nitrocelluloses
purified until they have reached their limiting state of minimum
evolution.

The dependence on temperature of the intrinsic evolution of nitrogen
from fully purified nitrocellulose has been worked out by Will, who
gives an equation expressing the quantity of nitrogen disengaged as
a function of the temperature. From this he calculates by exterpola-

VOL. XCV. 4 M

1242 ROBERTSON : THE VELOCITY OF

tion values for the disengagement of nitx'ogeu from nitrocellulose at
the ordinary temperature.

Will also discusses the nature of the decomposition of guncotton,
and draws the conclusion that the volatile nitrogenous gases evolved
consist for the most part of nitric oxide.

This view is not confirmed by a long series of experiments, in
which it is proved that not only under the conditions of the Will
test, but also in a vacuum and under other methods of treatment,
the nitrogen is evolved from normal guncotton to a large extent in
the form of nitric peroxide. The nitrogen in the latter form, in
which it was estimated by a specially worked out process of quan-
titative spectroscopic measurement of that gas, exists, indeed, under
the continuous removal of volatile products of the AVill test, to the
extent of more than 40 per cent, of the total nitrogen (Robertson
and Napper, Trans., 1907, 91, 761, 764).

Decomposition of Nitroglycerin {Glyceryl Trinitrate).

There is no previous knowledge of the mode of decomposition or
real stability of nitroglycerin, and its liability to such a process
of decomposition as has been shown to exist for nitrocellulose has
always been doubtful, especially in view of the obvious difference
between crystalloidal nitroglycerin — a compound of known molecular
weight and definite constitution — -and the corresponding nitric ester
of cellulose, of which the molecular weight is very high and the
constitution unknown.

The matter has remained in this condition for several reasons,
among which may be mentioned experimental difficulties connected
with the volatility of nitroglycerin when subjected to any process of
heating, and doubtless also the risks involved in dealing with this
substance at temperatures above the normal.

These difficulties have now been overcome to a great extent,
and an apparatus (Fig. 1) has been devised for investigating the
mode of decomposition of nitroglycerin without loss of that some-
what volatile substance from the experimental system, and also without
danger.

It may be stated at the outset that the results of the experiments
conclusively show that nitroglycerin, as well as the cellulose nitric
esters, undergoes an intrinsic decomposition, which is a function of
the temperature and is a fundamental property of the substance.

A description of the experimental methods and the results obtained,
together with a comparison of the latter with those given by gun-
cotton, are given below.

DECOMPOSITION OF NITROGLYCERIN J;V HEAT. I'AHT 1. 1243

Experimental.

A. Apparatus. — The apparatus used for the decompositiou is .sliown
in Fig. 1. Glass wool, made from Jeua glass, impregnated by soakin"
with 0-3 to 5*0 grams of.nitroglycoriii, is introduced into the horso-shoc-
shaped tube by means of the aperture fitted with a ground-in glass
plug, which is slightly greased with a non-reactive oil and further
sealed with mercury. By means of the glasscocks shown in the
di-awing, the current of carbon dioxide can be directed so that it
either passes down the right-hand spiral, through the glass wool
impregnated with nitroglycerin and up the other spiral, or vice versa.

Fio. 1.

SOCKET »»OtNT
COo STREAM

Decomposition vessel for nitrofjlycerin.

At one end of the apparatus is a slip-joint, so that the whole system
can be rotated on its axis. The point shown in the centre of the
horse-shoe is in the axis, and forms a supporting pivot.

The method of using the apparatus is clear from Fig. 2, which gives
the arrangement for one of the experiments.

The stream of carbon dioxide used for these experiments was
specially pure, and contained only 0*02 per cent, of gas unabsorbed
by potassium hydroxide solution. To prevent even the possibility of
the presence of oxygen, this carbon dioxide was passed over red hot
copper asbestos (Kreusler's) in «, and thence to the apparatus. When
the taps are open, as shown at b^ and b.^, the stream of gas is passed

4 M 2

12U

ROBEinVSON : THE VELOCITV OF

through spiral Sj, which is iimuersed iu an oil-bath, the temperature
of which is kuown, and is maiutaiiied uniform by a stirrer (not shown);
after traversing the ghiss wool impregnated with nitroglycerin, it
passes into spiral s.^, which is outside the heated oil, is protected from
radiation of heat from the oil by asbestos cards, and has impinging on
it a blast of cold air, h. In this way any nitroglycei'in that has been
volatilised iu the current of carbon dioxide is condensed in spiral Sg-
After a certain period (for example, half an hour), the whole apparatus
is rotated through 180° on its main axis, the two fixed points being
the slip-joint, c, and the pivot, d. The spiral, s^, cooled by the air
blast, now becomes the condenser of nitroglycerin, and any nitro-
glycerin which has been condensed in .s^^ is now returned to the heated
system. The spiral under the surface of the oil serves also as a pre-
heating worm, in traversing which the carbon dioxide is gradually
raised to the proper temperature of experiment. By means of this
arrangement, fixed glass tubes can be led from the rotating joint to
any apparatus for examining or measuring the gases, and the use of

Fig. 2.

jLJuuLi -^.^^v^ .^Jk, juum

Apparatus for cslivudiwj NO.j and total N from nitroglycerin.

K

rubber tubes, which are liable to attack by the nitrogenous gases, is
avoided. After the lapse of another period, the apparatus is again
rotated, when the spirals assume their reciprocal functions.

As a further precaution against the carrying over of nitroglycerin,
the gases pa.ss through an ice-cooled worm, J, immediately on leaving
the decomposition apparatus. The interposition of this worm has no
effect on the estimation of nitrogen existing as nitric peroxide.

After traversing the apparatus, the carbon dioxide, carrying with it
the volatile products, Avas examined in a number of ways. In all
cases, however, it was passed through an observation tube, e, and during
its passage through tbis the concentration of nitric peroxide was esti-
mated by the spectroscopic method of Kobertson and Napper {loc. cit.).
From the concentration of nitric peroxide, the weight of nitrogen dis-
engaged in this form was calculated. In most of the experiiuents the
gas, after traversing the oljservation tube, was led through a com-
bustion furnace {/), fitted with both reduced copper asbestos, to reduce
all the nitx'ogenous gases to nitrogen, and also with some copper oxide

DECOMPOSITION OF NITROOTA'OERIN P.Y HEAT. PAIJT I. 1 24r)

asbestos to oxidise any carbonaceous gases to carbon dioxide, for
absorption in the potassium hydroxide solntion contained in the
measuring burette (g). In the latter, the unabsorbed gases are read
off every (juartor of an hour, and calculated to weight of nitrogen after
deducting the previously determined nitrogen correction in the stream
of carbon dioxide, the rate of which was kept uniformly at 1000 c.c.
per hour.

B. Results. — (1) The disengagement of nitrogen proceeds in a
perfectly uniform manner. This is apparent from table I, wliich
shows the concentration of nitric peroxide estimated spectroscopically,
and the volume of nitrogen disengaged per quarter of an hour for
a period of four hours.

Table I.

Dpxomposilion of Nitroglycerin in a Current of Carbon Dioxide (it 120".
(0"5 gram of Nitroglycerin.)

Rate of Carbon Dioxide Stream — \QQf) c.c. i^er hour.

C.c. of No

C.c. of No

Concentra-

after com-

Coi

centra-

after com-

tion of

bustion, unab-

t

on of

bustion, ruiab

NO, gas in

sorbed by [tot-

NO

.J gas in

aorbed by pot

CO2 stream,

ash solution,

CO,

stream.

ash sobition,

spectroscopically

less nitrogen

spectr

oscopically

less nitrogen

Quarter

estimated iier

coiTection

Quarter

estimated per

correction

hour.

cent, by volume.

of the COo.

hour.

cent.

by volume.

of the CO.j.

1

0-04

0 05

n

0-13

0-15

2

0-07

O-lf)

10

0-13

0-10

3

0-09

0-15

11

012

0-15

4

o-ii

0-15

12

0-12

0-10

.5

0-11

0-15

13

0-12

0-15

G

0-12

0-1.5

I'l

0-12

0-15

7

0-12

0-1.5

15

0-12

0-10

8

0-12

0-15

1(3

0-12

0-15

(2) The nitrogen is disengaged from nitroglycerin as nitric peroxide,
(rt) It will be seen from the results given in table II, throughout a
considerable range of temperature, that agreement is obtained between
the total quantity of nitrogen evolved as estimated by a Dumas
combustion and the nitrogen estimated spectroscopically in the form
of nitric peroxide. '

In the same table are also given, for the sake of comparison, the
corresponding figures for guncotton according to (i) the exponential
formula given by Will {Zweite Mitt., p. 26), and (ii) a temperature-
coetficient of 2 for 5^^ (compare Brunswig, Kx2'>lossivstoffe, 1909,
p. 29).

124(J

ROBERTSON: THE VELOCITY OF

Table II.

Disengagement of Nitrogen from 2*5 grams.

Tempera-
ture.
135 0°
130-0
124-9
119-8
115-0
110-2
105-0
100-5
95-0
90-3

Nitroglycerin.

Total N (by
combustion).

4-87

2-72

1-62

0-74

0-36

0-20

0-10

0-044

0-021

0-009

N as NO. (by
spectroscopic
observation).

-.33

•90

•57

•80

•39

-20

-086

•043

-024

-010

Total N
(method i).
0-55
0-26
0-12
0-055
0-026
0-011
0^005
0^002
0-0008
0-0003

GuDcotton.

Total N
(method ii)
0-55
0-27
0-14
0 07
0-034
0-017
0-008
0-004
0-002
0-001

as N0.>
, & N.*)
0-23

1^

W

Trans., 1907, 91, 775.

[h) When the gases from the observation tube are led directly
into potassium hydroxide, in which all the nitric peroxide would be
absorbed together with as much nitric oxide as would combine to form
nitrogen trioxide, no nitric oxide is ever obtained. There is there-
fore no nitric oxide gas over and above the quantity required for the
equation NO + NO^ = N^Og.

(c) An analytical confirmation of the evolution of nitric peroxide
was obtained by leading the gases from the decomposition tube first
through the observation tube and then into bulbs containing sulphuric
acid. The latter was then shaken up in a nitrometer, and the nitrogen
existing as nitric peroxide calculated from the nitric oxide obtained.
The results showed that .the figure thus obtained agreed with the
figure from spectroscopic observation, being slightly lower on account
of the inclusion of the initial period before the cocstant disengagement

is established, thus :

From 2-5 grams of nitroglj'cerin
per qr. hour mg. Ng.
N as NOo estimated spectroscopically (at

constant evolution) 1^32

N as NO2 absorbed by H2SO4 (average of

16 quarters) 1*45

(3) The rate of disengagement of nitrogen is markedly increased by
rise in temperature.

In Fig. 3 are plotted temperatures and logarithms of disengagement
of nitrogen from the results given in table II. It will be seen that
between the temperatures of 95° and 1 25° the results fall on a straight
line.

From the rise in the logarithms a temperature-coefficient of 2 for 5°
is indicated throughout this range for increase in disengagement of
nitrogen from nitroglycerin.

DECOMPOSITION OF NITROGLYCERIN BY HEAT. PART I. 1247

(4) The quantity of nitrogen disengaged from nitroglycerin exceeds
that from guncotton when these two substances are treated under
similar conditions, that is, on heating, with removal of catalytic
volatile products of decomposition. This is evident from table II,
where the observed results from nitroglycerin are compared with those
given by guncotton, the disengagement from the latter being calculated
])y exterpolation according to both methods (i and ii on page 1245).

Fig. 3.

LOG MC.N,
PER QK.HR.
PER 2-5 CR.

0-8

0-6

0-4

0-2
0
-0-2
-0-4
-0-6
-0-8
-1-0
-1-2
-I-4
-1-6
-1-8
-2-0

WC 9S° 100' 105' 110° H5* 120* 125* 13©* I85»

Nitrogen from nitroglycerin, 90° to 135°.

By the method of hydrolysis, also, Silberrad and Farmer (Trans., 1906,
89, 1759) found the rate of hydrolysis of nitroglycerin to be much
higher than that of guncotton.

y

/

/•^ -

y

/

/<

/^ —

/

-

y

^/

y

/

y

—

■ y

<

/

y

f

__

/

^

Conclusions,

The decomposition of nitroglycerin with continuous removal of
volatile products has been studied at temperatures of 90" and upwards,
and the following conclusions are made from the results obtained.

(1) In a suitable apparatus the decomposition of nitroglycerin
proceeds in a manner as uniform as that of a stable guncotton when
the volatile products of decomposition are continuously removed.

(2) The nitrogen is disengaged for the most part, if not entirely,
as nitric peroxide, and the estimation of the nitrogen existing as
such by the spectroscopic method agrees with the results of estimation
by combustion and other methods. In this respect nitroglycerin
differs from guncotton, from which the nitrogen disengaged as nitric
peroxide at 135° amounts to only about 40 per cent, of the total
nitrogen,

124H FEIIRAROSCIII : THE OXIDATION OF

(3) Tho rate of decomposition is a function of the terapoiature, and
increases from 95" to 1 25'\ being doubled in a rise of 5'\

(4) Nitroglycerin has a higher rate of decomposition than guncotton
under similar conditions and at the same temperatux'e.

As the spectroscopic method is capable of estimating nitric peroxide
in even smaller concentrations than those already dealt with, further
work is in progress to determine the manner of the decomposition
of nitroglycerin at still lower temperatures without having recourse
to exterpolation.

In conclusion I have to thank Colonel Sir F. L. Nathan and Major
J. H. Mansell, K.A., for their interest in this work, and the Director of
Artillery for permission to publish the results.

Research Department,
Royal Arsenal,
"WooLwicn.

CXL. — The Oxidation of Mucic Acid in Presence

of Iron.

By Feederic Ferraboschi.

It has been shown by Fenton (Trans., 1S94, 65, 899 ; 1895, 67, 48 ;
1896, 69, 546; 1898, 71, 167, 472; Brit. Assoc. Reports, 1895,
1898, 1899, etc.) that various interesting oxidations can be effected
in presence of traces of ferrous ix'on as catalyst.

Fenton and Jones (Trans., 1900, 77, 76), in a general investigation
on the oxidation of various acids by means of hydrogen dioxide in
presence of iron, showed that mucic and saccharic acids on oxidation
yielded solutions which gave a deep reddish-violet colour with ferric
chloride and sodium hydroxide, and a precipitate with phenylhydr-
azine. The products of oxidation were stated to be very unstable, and
were not isolated or further examined.

An attempt to undertake such an examination has now been made
at Dr. Fenton's suggestion.

The oxidation of mucic acid was first investigated, and then parallel
experiments were made with saccharic acid.

The following method was generally adopted for the oxidation.
Mucic acid was boiled with a considerable volume of water, and a
solution of the lactone acid (" paramucic acid ") thereby obtained
(Fi.scher, Ber., 1891, 24, 21.36). A small quantity of pure metallic

MUOTO Ann IN PRESENCE OF IRON. 1249

iron ("forinxm redactum," — about 0*05 — O'l gram for every 10 grams
of mucic acid) was then dissolved in the solution. After cooling,
hydrogen dioxide (20 volumes) was added slowly, in the proportions
of 11 — 2 molecules of dioxide to one of the acid. Each addition of
hydrogen dioxide produced a deep brown coloration, which gradually
faded, and the next addition was not made until the colour had dis-
appcai-ed. The oxidation was carried out at the ordinary temperatui'e,
the large volume of water preventing any appreciable rise in tempera-
ture.

The solution obtained after oxidation gave as its most characteristic
reactions : Ferric chloride, followed hy sodium hydroxide. — Deep reddish-
purple colour, bleached by dilute sulphuric acid. Phenylhydrazine
acetate. — Orange precipitate, increasing on keeping.

Unaltered paramucic acid was always found to be present, its entire
oxidation not being effected even when a considerable excess of
hydrogen dioxide was used.

Action of Phenylhydrazine.

Phenylhydrazine acetate (al>out 1 molecule for each molecule of
hydrogen dioxide used) was added to the solution obtained after oxida-
tion. An orange-coloured precipitate was produced, the cjuantity of
which increased considerably on keeping at the ordinary tempei-a-
ture. After about forty hours the precipitate was collected.

It was a matter of considerable difficulty to obtain the substance in
a state of purity. Crystallisation from most of the or-dinary solvents
was tried without success, the method finally adopted being the follow-
ing. The substance was dissolved in excess of hot sodium carbonate
solution, the sodium salt being much more soluble than the dihydr-
azone acid itelf. Dilute hydrochloric acid was then added, when the
dihydrazone was again precipitated. It was collected and dried at lOO''.
Hot satin-ated solutions in alcohol and toluene were then made, and
the two mixed. The dihydrazone was deposited from the mixture,
on cooling, in minute, bright yellow needles, melting and decomposing
at 256° (quick heating).

The substance dissolves readily in benzene, toluene, or pyridine, is
less soluble in alcohol, ether, or chloroform, and only very slightly so
in water :

0-1920 gave 0-4148 CO^ and 0-0744 HgO. 0 = 58-92 ; H = 4-31,
0-1223 „ 15-75 c.c. Ng at 14° and 761 mm. N = 15-3.
C18H10O5N4 requires C = 58-70 ; H = 4-35 ; N= 15-2 per cent.

The compound would therefore appear to be the dihydrazone (or
osazone) of an oxidation product of mucic acid, minus a molecule of

1250 FERRABOSCHI : THE OXIDATION OF

water, its formula liaving either a lactone ring (I) or a pyrazolone
ring (II).

(I.) CO,H-CX:N2HPh)-CH<^^^^>C:N2HPh

(IT.) C02H.CH(0H)-CH(0H)-C<^^~~^pP^Jj>C0.

With the view of deciding between the two possibilities, the sub-
stance was titrated at about 40° against a solution of baryta, using
phenolphthalein as indicator. If the pyrazolone formula were correct,
it should act as a monobasic acid, whilst if the substance had the
lactone formula, it might, in presence of a base, act as a dibasic acid :

01477 of pure crystallised oxalic acid required 18"4 c.c. of the baryta
solution. 0"1903 of the substance required 8"3 c.c.

Calculated for lactone formula, 8*12 c.c.

Calculated for pyrazolone formula, 4'06 c.c.

The substance would, therefore, appear to have a lactone formula,
as represented above (I).

Action of Hylrogp^n Chloride on the Dihydrazone in Alcoholic

Solution.

The dihydrazone was dissolved in absolute alcohol, and the solution
saturated with dry hydrogen chloride. The liquid thus obtained
yielded on evaporation clusters of bright orange-coloured needles,
melting at 158° (quick heating) to a deep orange-red liquid. After
twice recrystallising from alcohol, no change in melting point was
observed, and the substance was therefore regarded as pure :

I. 0-0979 gave 0-2114 COg and 0-0451 H.,0. C = 58-8S; H = 5-12,
II. 0-1510 „ 0-.3253 COg „ 0-0689 H.O. C = 58-75 ; H = 5-ll.
III. 0-1820 „ 23-8 c.c. N2 at 16° and 749-4 mm. N = 15-2.

From the following reasons the substance appears to be an ester
derived from the dihydrazone.

(1) It does not dissolve readily in sodium carbonate solution in the
cold, but dissolves easily on warming. On adding dilute hydrochloric
acid to this solution, a precipitate is obtained which proves to be the
original dihydrazone.

(2) On digesting under reflux with sodium hydroxide and then
distilling, ethyl alcohol was found in the distillate, and recognised by
the iodoform reaction and by oxidation to acetaldehyde.

On account of the numerical approximation between the compositions
calculated for vai-ious ester-formulie, it is not possible, from the
analytical figures, to assign to it a definite constitution.

MUCIC ACID IN PRESENCE OF IRON. 1251

DiJiydroxymucic Acid.

With the view of isohiting the products of oxidation, the solution
resulting after the oxidation of paramucic acid was evaporated at about
60 — 80° to a syrup. Darkening in colour always occurred during the
process. The syrup was then extracted several times with alcohol.
The alcoholic solution gave the characteristic reactions with ferric
chloride and phenylhydrazine acetate, and reduced ammoniacal silver
nitrate and Fehling's solution very strongly. It contained a consider-
able quantity of a substance which appeared, for reasons discussed at
the end of this paper, to be ethyl hydrogen mucate. This was, to a
large extent but not entirely, precipitated by adding to the solution
several times its own volume of ether ; most of the iron, which was
still present in traces, being carried down at the same time. The
filtrate, after concenti'ation to a syrup in a vacuum over sulphuric acid,
deposited in the course of several days crystals of an acid which was
found to have very strong reducing properties.

The above method of isolating the acid only yielded it in very small
amount. An attempt was therefore made to isolate it from its lead
salt. The lead salt, mixed with lead mucate, was precipitated by
addition of lead acetate to the solution obtained after the oxidation.
The mixed lead salts were suspended in ether, into which hydrogen
sulphide was then passed. Since mucic acid is insoluble in ether, this
process effected the separation of the oxidation product from the
unaltered mucic acid. The ethereal solution was evapoi-ated in a
vacuum, and yielded a syrup which slowly deposited crystals of the
acid.

The acid was found to be soluble in water, alcohol, or acetone, and
less soluble in ether ; it melted and decomposed at 205 — 207°. In
aqueous solution it instantly reduced ammoniacal silver nitrate in the
cold, and reduced Fehling's solution in the cold or on very slightly
warming. With ferric chloride, no coloration was produced, and on
subsequently adding sodium hydroxide, a precipitate of ferrous
hydroxide was formed.

It is obvious from these facts that the oxidation must yield at least
two products, since the substance isolated does not give the colour
reaction with ferric chloride which is characteristic of the solution
obtained after oxidation.

Owing to the instability of the product, it was only obtained in very
small amount. It has therefore not yet been possible to prepare by
recrystallisation a sample sufficiently pure for very accurate analysis.
A specimen which had not been recrystallised gave the following
figures :

1252 THE OXIDATK^X OF MUCIO ACID TN PRESENCE OF IRON.

0-1225 gave 0-1373 CO,, and 0-0459 H2O. C = 30-57 ; H-4-20.
Mucie acid, CJijo^^- + 20 requires G = 29 -75 ; H -= 417 per cent.
I'he substance therefore appears to be a dihydroxymucic acid, its
constitution, as appears below, being probably represented by the
formula (I), and to react with pheuylhydrazine as dihydroxydiTcelO'
(I.) COoH-C(OH)2-CH(OH)-CH{OH)'C(OH)2-C02H
(II.) C02H-CO-CH(OH)-CH(OH)-CO-C02H,2H20
adijnc acid (IT), yielding the dihydrazone, which has been prepared.

Oxidation of Saccharic Acid in Presence of Iron.

It is obvious that further light could be thrown on the constitution
of the products of oxidation by examining whether or not saccharic
acid yielded products identical with those obtained from mucic acid.

Potassium hydrogen saccharate was therefore dissolved in water,
together with sufficient sulphuric acid to liberate free saccharic acid.
The solution was then treated in exactly the same way as that
employed in the oxidation of mucic acid. After concentrating the
solution, extracting with alcohol, and concentrating the alcoholic
extract, a syrup was obtained which showed the reactions charac-
teristic of the syrup obtained in the same way from mucic acid.

The dihydrazone was prepared and purified under the same con-
ditions as those adopted in the case of mucic acid. It was found
to be an orange-yellow, microcrystalline substance, melting and
decomposing at 242 — 244° (quick heating). When mixed with about
one-quarter of its weight of the dihydrazone obtained from mucic acid
(m. p. 256"), the melting point was depressed to 239 — 241° :

0-1790 gave 23-45 c.c. N2 at 14° and 764-5 mm. N= 15-6.

From these facts it would appear that the two dihydrazones have
the same composition, but not identical configurations.

An ester was prepared fi-om the dihydrazone in the same way as the
ester of the diliydrazone derived from mucic acid. It consisted of
bright orange-coloured needles, melting to a deep orange-red liquid at
164 — 165° (quick heating). A mixture of the two dihydrazone esters
melted at 156°.

The fact that the oxidation products of mucic and .saccharic acids
yield derivative.'^ which are not identical is in agreement with the
constitution for dihydroxymucic acid proposed above.

Note on Ethyl Hydrogen Mucate.

Fischer (Ber., 1891, 24, 2142) states that an alcoholic solution of
" paramucic acid," containing tx-aces of metallic salts, deposits a
cry.stallinesubstance"meltingataboutl75"," which "from the analyses,

DIPHENVLAMINK OKTIIO-SULrHUXIDES. 1258

which gave no sharp figures, proba'»ly consists lor the most part ot" tlio
monoethyl ether of miicic acid."

The crystals deposited from the alcoholic extract after the oxidation
of paramucic acid (p. 1251) gave as the mean of three not very con-
cordant analyses : C = 39"15, H = 5'97 (ethyl hydrogen mucate requires
(j = 40o-l, H = 5'88 per cent.), and melted at temperatures ranging
between 175° and 181°. These facts arc in agreement with Fisclier's
description of the substance supposed by him to be impure ethyl
hydrogen mucate.

The substance has an acid reaction, is soluble in water or alcohol,
but practically insoluble in ether. It reduces Fehling's solution on
boiling, and gives a " silver mirror," in these respects resembling
pai'amucic acid.

Titration with baryta gave the following result :

0*0200 of pure crystallised oxalic acid required 28 '7 c.c. of the
baryta solution. 0'0766 of the substance required 28"5 c.c.

Calculated for ethyl hydrogen mucate, 29' 1 c.c.

The substance may therefore be rogardel as identical with Fischer's
impure ethyl hydrogen mucate.

I wish to express my sincere gratitude to Dr. Fenton for suggesting
to me the above line of investigation, and for his valuable advice
during its progress.

Tuii UNiVEKsrrv Chemical L.vbouatouy,
Camduidge.

(JXLT. — Tlte Intramolecular Rearrangement oj Diphenyl-

aminc ortho-Sulphoxides.

By Edward dk Bakuy Baknett and Samuel Smiles.

Ix continuing the study of the derivatives of /S'-phenylphenazo-
thionium, we desired to obtain a sulphoxide of diphenylamine which
possesses stronger acidic properties than tlie dinitro-compounds
previously employed, and for this purpose we undertook the prepara-
tion of the polynitro-derivativos of this group. The nitration of thio-
diphenylamiue has been studied by Bernthsen {Annalen, 1885, 230,
IIG), who, by carefully regulating tiie action of the nitric acid,
isolated the di-para- and isodinitro-derivatives. We find tliat by
conducting the nitration under more severe conditions, the tetrauitro-
sulphoxide is formed, in accordance with the facts previously

1254

BAUNETT AND SMILES : THE INTRAMOLECULAR

collected by Bernthsen (loc. cit.) from the dinitro-compounds, and by
Stormer and Hoffniaun {Ber., 1898, 31, 2535) from the nitration
of dipheuylamine, aud also from the general rules governing the
nitration of aromatic amines, the tetranitio-sulphoxide must have the
constitution (I).

Daring the investigation of this sul)stance it was observed that
with certain reagents — such as a solution of hydrochloric acid in
concentrated sulphuric acid — it is transformed into an isomeric
compound, and, extending the inquiry to other sulphoxides of this
series, we have found that the transformation is a general one.

It will be shown that the reaction consists essentially in the
conversion of the imino-sulphoxide structure (II) into the ortho-
quinonoid azothionium arrangement (III).

NO., NH NO., NH N

NO.,

NO.,

''"'^' ' ' I | + H,0.
/\

SO so S-OH

(I.) (II.) (III.)

The reaction cannot be strictly termed au isomeric change, since under

ordinary circumstances the azothionium products are found to contain

a supplementary molecule of water, which as a rule does not occur in

the sulphoxides. This molecule of water may, however, be removed,

and the tetranitro-sulphoxide which contains the additional water

yields an isomeric azothionium hydroxide.

On general considerations it might be considered possible that

in this reaction fission of the thiazine ring (IV) takes place. If this

were the case, the red substances obtained would have either the

structure of a diphenylaminesulphinic acid (V) or that of an amino-

phenol sulphoxide (VI).

NH NH

^^^|0H NH.,f
-SO-

I ^Oo]

SO SOgH

(IV.) (V.) (VI.)

But apart from the improbability of this occurrence, these
structures for the products of the reaction must be rejected, chiefly for
the following reasons :

(i) It is difficult to imagine how sub.stances of either of these types
could lose water without producing the original sulphoxide.

(ii) The dinitro-products do not show the weakly acidic properties
of the corresponding sulphoxides. They do not form sodium salts
under the usual conditions with aqueous alkali hydroxide, whereas
substances of either of these structures (V or VI) must do so.

REARRANGEMENT OF DIl'HENYLAMINE OKTHO-SULPHOXIDES. 1255

(iii) The unsubstituted derivative obfcaiaed from diphenylamine
ortho-sulphoxide is a base of moderate strength, since tlio salt is incom-
pletely hydrolysed by boiling aqueous sodium carbonate. According
to the latter of the given structures, the substance should be a weak
base, and according to the former, an acid,

(iv) We have not been able to obtain benzoyl or alkyl derivatives
of these substances.

The reaction was first studied with the previously-meutioned nitro-
gulphoxides, and in these cases there are only two alternative structures
for the isomeric products :

N N

NOol

SO S-OH

(VII.) (VIII.)

According to the fir.st scheme they would be represented as para-
quinonoid nitronic acids, and according to the second, as ortho-
quinonoid sulphonium hydroxides.

That the first alternative cannot be entertained is evident from tlie
following considerations :

(i) The tetranitro-sulphoxide when treated with dilute aqueous
sodium hydroxide is converted into a red sodium salt, which, accord-
ing to the researches of Hantzsch and many others on similarly
constituted compounds, must contain the para-quinonoid structure. By
carefully treating the sodium salt with mineral acid, the red niti'onic
acid is liberated, but it is very unstable, and, during the process
of isolation, changes into the original bright yellow sulphoxide. The
product obtained from the tetranitro-sulphoxide by the action
of hydrochloric acid cannot be the nitronic acid, for it is a quite
stable substance, and, in fact, is formed when the sulphoxide is
heated to about 180°.

(ii) In alcoholic solution with sodium ethoxide the tetranitro-,
di-para-nitro-, and isodinitro-sulphoxides form red solutions of the
nitronic salts. If the red isomeric forms of these sulphoxides had the
nitronic structure, they should yield the same salts under these con-
ditions ; but they do not, their salts being green or blue in alcoholic
solution.

(iii) The dinitro-compounds do not form salts with dilute aqueous
sodium hydroxide, and are thus of weaker acid character than the
sulphoxide foi'ms, -which yield salts under these conditions. It has
previously been shown (Smiles and Hilditch, Trans., 1908, 93, 149)
that the entrance of nitro-groups into the benzene nucleus of
thiodiphenylamine weakens the basic properties of the quadrivalent

1256 lUKNETT AND SMILES: THE INTRAMOLECULAR

isulphur in tlie derivatives of AS'-phenylpheuazoLliionium. Moreover,
Kelirniauu (Ber., 1906, 39, 914) has observed a similar relation
iu the ortho-quiuonoid derivatives of phenazothionium. If this
intramolecular rearrangement does not involve the nitro-groups,
but merely concerns the thionyl and imino-gi'oups of these sulph-
oxides, it follows that the unsubstituted diphenylamine sulphoxide
(IX) ishould iiudergo the same change ; moreovei-, the nitro-groups

-> I I --> ,

SO S-OH SGI

(IX.) (X.)

liein<' removed, the sulphonium base should be of stronger charac-
ter and should furnish more stable salts (X). This is actually
the case. Diphenylamine ortho-sulphoxide is formed by the inter-
action of hydrogen dioxide and thiodiphenylamine. The constitution
of the product of this reaction might be considered doubtful, since
Dunstan and Goulding (Trans., 1899, 75, 792, 1004) have shown that
hydroiien dioxide converts the secondary aliphatic amines into di-yS-
alkylhydroxylamines, but ample proof that the substance is a sulph-
oxide and does not contain the alternative hydroxylamine structure is
afforded by the facts : (i) that under the same conditions diphenyl-
amine is not attacked by hydrogen dioxide ; (ii) that the substance
does not show the strong i-educing properties to be expected of a
hydroxylamine dei-ivative ; and (iii) that hydrogen dioxide converts
the aromatic sulphides into sulphoxides (Gazdar and Smiles, Trans.,
1908, 93, 1833).

When this sulphoxide is submitted to the action of aqueous hydro-
chloric acid it is at once converted into phenazothionium chloride,
thus giving final proof that the products of this reaction possess the
azothionium structure. It may be observed that Kehrmaun {Ber.,
1901, 34, 4170) has already obtained the chloride and other salts
of phenazothionium by the acid oxidation of thiodiphenylamine.

From a comparison of the formulae of the sulphoxides with those of
the corresponding sulphonium bases, it would seem that this intra-
molecular change merely consists of the migration of hydrogen from
the imino-group to the oxygen of the thionyl group. "VVe have found
reason for believing that this is not the true explanation of the
reaction, but that the latter instead takes place by migration of
hydroxyl from the quadrivalent sulphur to tervalent nitrogen. Since,
however, our experiments are not yet complete, we reserve the dis-
cussion of this question for a future occasion. At present it is

REARRANGEMENT OF DIPHENYLAMINE ORTHO-SULPHOXIDES. 1257

sufficient to observe that, to be satisfactory, any theory of the
mechanism must account for the following facts :

(i) The reaction proceeds more easily the stronger the basic
character of the quadrivalent sulphur.

(ii) At least with the unsubstituted sulphoxide, the change is
favoured by increasing the concentration and strength of the acid.

(iii) The anomalous behaviour of the tetranitro-sulphoxide, which,
although the most difficult of the serie.s to convert with acid reagents,
is the only one transformed by the action of heat.

(iv) The absorption of the elements of water during the reaction.

It is our intention to extend the study of this reaction to aromatic
hydroxy- and amino-sulphoxides and sulphonium bases.

Experimental.
Tetranitro-derivatives.
Tetraniirodiphenylamine Sulphoxide,

(N02)2C,H2<f^l>C,H2(N02)2.

— Thiodiphenylamine is heated in an open vessel for about two houi^s
with an excess of fuming nitric acid (D 1'5), and the solution is then
poured into an excess of water and washed until the acid is completely
removed. It is difficult exactly to define the conditions necessary to
obtain a pure product. If the action be allowed to proceed too far,
the liquid will be found to contain sulphuric acid, and the product
must then be treated with acetone to remove the polynitro-derivatives
of diphenylamine which are formed. If, however, the i*eaction be
stopped at a suitable point before sulphuric acid appears in the
solution, the product is almost pure and the yield quantitative. A
sample was prepared for analysis by crystallisation from nitrobenzene,
and it was thus obtained in minute, lemon-yellow crystals :

0-0966 gave 0-1285 CO, and 0-0219 HgO. C- 36-27; H = 2-5.
0'1984 „ 0-2671 00." „ 0-0378 HgO. 0 = 36-71 ; H = 2-1.
0-4278 „ 0-2484 BaSO^. S = 7-97.

CJ2H5O9N5S requires 0 = 36-54 ; H=l-27; S = 8-10 per cent.

When recrystailised from ^j-tolyl methyl ether the substance
separates in long needles which contain the solvent, but the latter
may be removed by washing with alcohol or ether, when the crystals
break up into a fine powder. Probably these crystals contain two
molecular proportions of the phenolic ether, but the correct amount is
difficult to determine, since it is very loosely combined. Two samples
were analysed.

VOL. XCV. 4 N

1258 BAENETT AND SMILES: THE INTRAMOLECULAR

(1) Dried in a vacuum :

0-0843 gave 0-1500 CO2 and 0-0306 HgO. C = 48-53 ; H = 4-03.

(2) Dried in air at atmospheric temperature and pressure :
0-1391 gave 0-2572 CO.^ and 0-0562 H2O. C = 50-42; H = 4-49.

Ci2H503N5S,C8Hi„0 requires 0 = 464 per cent.
G,;hAN5S,(C3H,,0)2 „ 0 = 56-3 „

The product obtained by the correct nitration of thiodiphenylamine,
and without further purification with high boiling solvents, is the
pure sulphoxide, but it now contains an additional molecule of
water. A sample which had been dried in the steam-oven was
analysed :

0-1041 gave 0-1331 OO2 and 0-0162 HgO. 0 = 34-87; H = l-73.

0-4462 „ 0-2540 BaSO^. S = 7-88."

0-1876 „ 27-8 c.c. N2 at 20° and 744 mm. N = 16-90.
OijHjOgNjS.HgO requires 0 = 34-81; H=l-69; S = 7-75; N = 16-95

per cent.

When this substance is heated to 180 — 200°, only a slight loss in
weight occurs, but the greater portion of the sulphoxide is transformed
into the sulphonium hydroxide. That this hydrated sulphoxide is not
the sulphone, which differs from it only slightly in elemental com-
position, is proved by the fact that it may be reduced to diamino-
thionine, and it appears from the work of Bernthsen (Ber., 1906, 39,
1807) that the nitrosulphones of this series are not thus converted
into thionine derivatives. Moreover, it will be later shown that the
substance may be condensed with phenetole, yielding the salt of the
/S'-phenetyl derivative, and this reaction shows the presence of the
thionyl grouping.

Tttranitrodijihenylamine ortho-suljyhoxide does not melt below 250°
and it is very sparingly soluble in the usual organic media of low
boiling point.

Sodium Salt. — This sulphoxide behaves as a weak acid, and with
aqueous sodium hydroxide furnishes a scarlet sodium salt. When
boiled with this reajjent some decomposition takes place, one or more
nitro-groups being displaced, but when triturated with a warm aqueous
solution of the alkali hydroxide a red, flocculent precipitate is deposited.
Estimation of sodium in two different samples showed that it is
probably an acid salt :

0-3533 gave 0-0269 Na2S04. Na = 2-47.

0-4160 „ 0-0369 Na2S04. Na = 2-87.

Oi2H40gK5SNa,Oj2H50pN5S requires Na = 2-85 per cent.

It seems to be very readily decomposed into its components by
treatment with cold acetone, which dissolves the normal sodium salt,
leaving the sparingly soluble yellow acid.

REARRANGEMENT OF DIPHENYLAMINE ORTHO-SULPHOXIDES. 1259

A sample of the sodium salt obtained in this manner was
analysed :

0-4160 gave 0-0503 Na^SO^. Na= 4-36.

CjjH^OgNjjSNa requires Na = 552 per cent.

The addition of dilute mineral acids to the aqueous solution of the
sodium salt furnishes a precipitate of a red form of the sulphoxide.
A sample of this substance was collected and washed with cold water
until free from excess of acid, but on being dried in the steam-oven
for analysis it rapidly changed colour, and finally became orange-
coloured :

O'lOlO gave 0-1287 CO., and 0-0187 HgO. C = 34-75; H = 2-10.
C10H.O9N5S requires C = 34-81 ; H= 1-69 per cent.

Diaminothionine. — Tetranitrodiphenylamine ortho-sulphoxide was
mixed with alcohol and reduced with tin and hydrochloric acid in the
usual manner. The colourless solution was mixed with excess of
aqueous ferric chloride, and finally the precipitation of the dye was
completed by the addition of salt solution. The precipitate was
collected and treated with concentrated hydrochloric acid, which
dissolved the amino-derivative, leaving the insoluble residue of
inoiganic matter. The dye-stuff was obtained in deep blue scales by
mixing the hydrochloric acid solution with water and keeping the
mixture for some days at the atmospheric temperature. Several
unsuccessful attempts were made to remove by physical means the
excess of hydrochloric acid contained in this substance, but analysis
showed that the content of carbon was too low, and that of halogen
too high, for the monochloride, and these did not correspond with
any definite formula. However, it seems that treatment with dilute
aqueous sodium carbonate removes the excess of acid, since it was
found that

0-1006 gave 0-1615 CO.2 and 0-0354 HgO. C = 43-7; H = 3-9.
C^2Hi2N5ClS,2H20 requires C = 43-76; H = 4-25 per cent.

but further analysis of the substance was not made.

Diaminothionine chloride is soluble in hot water or alcohol. In the
latter solvent it exhibits a red fluorescence.

The platinichloride was obtained as a brown, crystalline powder by
adding aqueous chloroplatinic acid to a solution of the chloride :

0-3351 gave 00732 Pt. Pt = 21-55.

Cg^Hg^NjQCIgS^Pt requires Pt = 21-10 per cent.

Teiranitrophenazothioniuvi hydroxide,

— The following methods of preparation were carried out with the

4 N 2

1260 BARNETT AXD SMILES: THE INTRAMOLECULAR

hydrated form of the sulphoxide, the analysis of which is described on
a former page.

(a) With Hydrochloric Acid in Sulphuric Acid Solution. — Unlike
the other sulphoxides of this series, the tetranitro-derivative dissolves
in concentrated sulphuric acid without intense colour ; the solution is
a greenish-yellow colour. The addition of hydrochloric acid to this
solution causes the appearance of a bright red colour, and the reaction
is a very delicate one. The same effect is produced by phenetole and
similar compounds, and it will be shown later that with these reagents
the *S'-phenyl derivatives of the series are formed. It may be remarked
that with thiophen the reaction is so delicate that it may be used as a
test for the presence of this substance in benzene.

A mixture of excess of concentrated sulphuric acid with tetvanitro-
thiodiphenylamine ortho-sulphoxide was saturated at atmospheric tem-
perature with hydrogen chloride. The passage of the gas was continued
for about twenty-four hours, and the mixture was continually stirred.
When the yellow particles of the sulphoxide seemed to have completely
disappeared, the deep red solution was filtered through glass wool and
then slowly poured on to pounded ice. The precipitate was collected
and washed until the sulphuric and hydrochloric acids were completely
removed. After purification the substance contained no halogen :

0-1926 gave 0-2594 COg and 0-0392 HgO. 0 = 36-73; H = 2-26,
0-1974 „ 0-1007 BaSO^. S = 7-70.
C12H5O9N5S requires C = 36-46 ; H = 1-27 ; S = 8-09 per cent.

It may be observed that the transformation does not take place with
sulphuric acid alone, and this distinguishes the tetranitro- from the
other derivatives which are readily converted by this reagent.

(b) With an Alcoholic Solution of Hydrochloric Acid. — The tetranitro-
sulphoxide was mixed with a solution of hydrogen chloride in absolute
alcohol which had been saturated with the gas at the atmospheric
temperature. A portion of the sulphoxide at once dissolved, giving
a deep red solution. The reaction was allowed to continue (1) by
keeping the mixture at the laboratory temperature for twenty-six days,
or (2) by heating the mixture in a sealed tube to 150° for five hours.
In the latter case, when the cold tube had been opened and the excess
of ethyl chloride had been allowed to evaporate, the thionium hydroxide
was obtained in large, blunt, bright red prisms. After purification,
the products from the two sources were dried at 100° and analysed :

(I) 0-1045 gave 0-1337 COg and 00194 HgO. 0 = 34-89 ; H = 2-07.
(11)0-1033 „ 0-1316 CO.;, „ 0-0205 H2O. 0 = 34-84; H = 1-81.
O12H5O9N5S requires 0 = 34-81 ; H= 1-69 per cent.

Tetranitrophenazothionium hydroxide does not melt below 250°. It
is insoluble in water and very sparingly soluble in the usual organic

REARRANGEMENT OF DIPHENYLAMINE ORTHO-SULPHOXIDES. 1261

solvents, but it is rather more soluble in acetone, giving a red solution
from which it is deposited on spontaneous evaporation in red needles.
Tetranitrophenazothionium hydroxide may also be obtained by heating
the sulphoxide to ISO — 200° for a few hours. No appreciable loss of
weight takes place, and the product is dark red in colour, and furnishes
the green colour with alcoholic alkali hydroxide which is characteristic
of the azothionium form.

Sodium Salt. — When triturated at the ordinary temperature wi'th
10 per cent, aqueous alkali hydroxide, tetranitrophenazothionium
hydroxide fox'ms a sticky, green mass, which is converted by cold
water into a red sodium salt. This could not be obtained sufficiently
pure for analysis. The alcoholic solution of this tetranitro-derivative
gives a green colour with sodium ethoxide.

Oxidation. — Tetranitrophenazothionium hydroxide is readily attacked
by concentrated nitric acid, and is thereby oxidised to the sulphone.
After purification, tbe product of this reaction was analysed :

0-1004 gave 0-1292 COg and 0-0250 H.O. C = 35-05 ; H = 2-76.
C12H5O10N5S requires C = 35-04 ; H = 1-22 per cent.

That the substance is not the hydrated form of the sulphoxide is
shown by the action of alkali hydroxide, which furnishes a well-defined
crystalline salt, and by the very weak red coloration produced by
adding hydrochloric acid to the sulphuric acid solution of the substance.
The weak colour produced is no doubt due to the presence of traces of
the sulphoxide in the azothionium hydroxide.

Dinitro-derivatives.

The dinitrodiphenylamine sulphoxides employed were those pre-
viously obtained by Bernthsen (loc. cit.) by the regulated action of
nitric acid on thiodiphenylamine. These substances are far more
readily converted into the azothionium compounds that the tetranitro-
compounds described in the previous pages ; in fact, the rearrangement
can be effected by sulphuric acid or alcoholic hydrochloric acid in a
few hours at the laboratory temperature.

3 : Si-Dinitrophenazothionium Hydroxide,

.N-

N02-C,H3<^^^Qg.^>0,H3-N02.H20.

! Di-jo-nitrophenylamine sulphoxide was treated in the three following
ways :

(a) Concentrated Sulphuric Acid. — The rearrangement of the
sulphoxide to the azothionium form takes place only slowly with
this reagent, and it is difficult to obtain a pure pi-oduct, since the
azothionium hydroxide is decomposed by the acid before the sulphoxide
has been completely transformed. In one experiment the : brown

1262 BARNETT AND SMILES: THE INTRAMOLECULAR

solution of the sulphoxide in sulphuric acid was kept foi* one hour
and then poured into water. After being pui'ified and dried, a sample
was analysed :

0-1011 gave 0-1745 CO^nnd 00269 HgO. 0 = 47-07; H = 2-9.
C12H-O5N3S requires C = 47-2 ; H = 2-3 per cent.

The product was evidently a mixture of the sulpho:^ide and the
sulphonium form, since it was pale brown in colour and did not give
the pure green with alcoholic alkali hydroxide.

In another experiment the solution of the sulphoxide in concen-
trated sulphuric acid was kept for a longer time, A.fter sixteen
hours the solution had become green, and had a strong odour of
oxides of nitrogen. The precipitate now formed by pouring into cold
water was collected, and, after thorough washing, was extracted with cold
dilute sodium hydroxide solution, in which the greater part dissolved.
The alkaline solution was acidified, and the precipitate was collected,
dried, and recrystallised from nitrobenzene. The treatment with
aqueous sodium hydroxide was repeated. An analysis of a purified
sample gave the following result :

0-1856 gave 0-3292 00^ and 0-0646 H2O. C = 48-4; H = 3-8.
^12^1005^28 requires 0 = 48-9; H = 3-4 per cent.

These data show that the dinitrophenazothionium hydroxide (I)

at first produced is acted on by the excess of sulphuric acid, nitrous

acid being liberated and hydroxyl being intiodujped in place of the
nitro-group.

N N

NO2I i X M^2 ^ NO2I Av i JOH +HNO2.

S-OH S-OH

(I.)

Z-Nitro-^-hydroxyphenazothionium hydroxide forms minute, reddish-
brown crystals, which are insoluble in water and alcohol. The solutions
in aqueous sodium hydroxide are reddish-violet.

(b) With Ilydrochloric Acid in Sulphuric Acid Solution. — The
process employed was similar to that described under the tetranitro-
derivative ; but here the reaction was complete in about four hours.
As obtained by this method, the product was isomeric with the original
sulphoxide, and it did not contain halogen :

0-1000 gave 0-1725 OOg and 0*0264 HgO. 0 = 47-04 ; H = 2-9.
0-2655 „ 0-2084 BaSO^. S = 10-76.

O12H.O5N3S requires 0 = 47-2 ; H = 2-3 ; S = 10-49 per cent.

Analysis of the sample of sulphoxide employed in this reaction gave
0 = 47-2 per cent.

REARRANGEMENT OF DIPHENVLAMINE ORTHO-SULPHOXIDES. 1263

(c) With Alcoholic Hydrochloric Acid. — The finely powdered sulph-
oxide was shaken with this reagent for four or five hours at the
laboratory temperature. If the quantity of the reagent taken be
sufficient to dissolve the sulphoxide, the transformation can be more
rapidly effected, since then the azothionium hydroxide crystallises
from the solution in about one hour or even less. In either case the
crystalline mass was separated from the mother liquor, and washed with
alcohol an<%finally, with water. The pi'oduct did not contain ionisable
halogen, but it was observed that if the action of the halogen acid was
prolonged, or if the temperature was allowed to rise above the ordinary
limits, traces of halogens may be present in other forms of combina-
tion. This impurity seems to consist of a colourless substance, which
we have isolated but not yet fully examined. The crude product was
crystallised from nitrobenzene or from aniline :

0-1502 gave 0-2432 COg nnd 0-0396 H2O. C = 44-16 ; H = 2-93.
0-0967 „ 10-8 c.c. Ng at 13° and 767 mm. N= 13-25.
Ci,H705N3S,H20 requires C- 44-58; H = 2-8 ; N=13-0 per cent.

The supplementary molecule of water present in the substance
prepared in this manner cannot be removed at 100°, and attempts to
displace it at higher temperatures were unsatisfactory, since some
decomposition seemed to take place.

3 : ^-Dinitrophenazothionium hydroxide is insoluble in water, alcohol,
or ether, slightly soluble in hot glacial acetic acid, and. easily so in hot
aniline or nitrobenzene. It forms chocolate- brown needles, which melt
and decompose at about 240°. Solutions in concentrated sulphuric
acid are deep green in colour.

Sodium Salts. — The azothionium hydroxide does not form salts with
cold aqueous alkali hydroxide, and it is apparently decomposed by the
boiling reagent. With alcoholic alkali hydroxide it yields an intense
green coloration. This behaviour sharply distinguishes the substance
from the corresponding sulphoxide. The latter is sparingly attacked
by cold aqueous alkali, giving bright red solutions of the sodium salt,
and it is readily soluble in the alcoholic reagent, producing the same
colour. When the sulphoxide is warmed with aqueous sodium hydroxide,
the sodium salt is readily obtained in well defined, glistening scales.
Two recrystallised specimens of this salt were dried in the steam-oven
land analysed :

(a) 0-2198 gave 0-0310 NagSO^. Na = 4-59.

0-2181 „ 0-1560 BaSO^. S = 9-81.
(6)0-2844 „ 0 0381 NagSO^. Na = 4-34.
Ci2HAN3S/2Ci2Hg05N3SNa requires N'a = 4-79 ; S= 10-0 per cent.

Reduction of the dinitroazothionium hydroxide with zinc dust and

1264 HARNETT AND SMILES: THE INTRAMOLECULAR

hydrochloric acid, and subsequent oxidation of the leuco-base with
ferric chloride, furnishes thionine.

Oxidation with chromic acid in glacial acetic acid solution yields a
bright 5'ellow, crystalline substance, which is soluble in hot nitrobenzene
and does not melt below 250° :

0-1047 gave 0-1642 COg and 0-0264 H2O. C = 42-76 ; H = 2-8.
CioHyO^NgS.HoO requires C = 42-48 and H-2-65 per cent.

This siibstance is therefore probably the .^ulphone, but we have been
unable to prove that fission of the thiazine ring has not taken place.

isoDiniirophenazotMoniumIIydroxide,1^02'OQK^'^(^,^y^y>CQ'H^'1^02.

— This was prepared from ^'sodinitrodiphenylamine sulphoxide by the
action of alcoholic hydrogen chloride, the procedure being the same as
that previously described for the other nitro-derivatives. The trans-
formation is effected in about the same time as that of the di-/?-nitro-
sulphoxide. The product which crystallised from the acid mother
liquor was thoroughly washed with alcohol and water, and if care be
taken to regulate the action of the halogen acid, the substance thus
obtained is quite free from halogen, and consists of the pure hydrated
form of the thionium derivative. A sample which had been dried at
100° was analysed :

0-1000 gave 0*1622 00, and 00255 HgO. C = 44-24 ; H = 2-83.

0-2551 „ 0-1854 BaSO^. S = 9-96.

CiaHyOsNgS.HgO requires C = 44-58 ; H = 2-8 ; S = 9-91 per cent.

When the substance was crystallised from aniline, it was obtained
in the anhydrous form :

0-1002 gave 0-1749 CO2 and 0-0242 HgO. C-47-60; H = 2-6.

0-1596 „ 19-2 C.C.N2 at 12° and 744-6 mm. N= 1.3-93.
C12H.O5N3S requires C = 47-2; H = 2-3; N = 13-77 per cent.

iso Diniirophenazothionium hydi-oxide is insoluble in cold alcohol or
water, and readily soluble in hot aniline or nitrobenzene. It forms
chocolate-coloured needles, which melt and decompose at 199°. In its
chemical behaviour the substance closely resembles the di-^j-nitro-
compound. It does not yield an alkali salt with cold aqueous sodium
hydroxide, but the alcoholic solution when mixed with sodium hydr-
oxide develops a deep blue colour. It is readily soluble in concentrated
sulphuric acid, the solution being reddish-brown in colour.

Reduction and oxidation furnish similar products to those obtained
from the di-jo-nitro-compound.

REARRANGEMENT OF DIPHENYI.AMINE ORTHO-SULPHOXIDES. 1265

Unauhstituled Derivatives,

Dipkenylamine ortho-Sulphoxide, CgH4\o.-^_J>C„H^. — A solution of

5 grams of thiodiphenylamine in about 150 c.c. of acetone was rendered
alkaline with a few drops of sodium ethoxide solution. Three grams
of a 30 per cent, solution of hydrogen dioxide were then added, more
acetone being added if necessary to retain the diphenylamine in
solution. The mixture was then kept at the atmospheric temperature.
The sulphoxide was gradually deposited in large, prismatic needles,
which at the end of ten days were collected, 3 grams being obtained.
Diphenylamine ortho-sulphoxide obtained in this manner is almost
pure, but it may be recrvstallised from acetone, in which it is sparingly
soluble :

0-1023 gave 0-2501 CO,, and 0-0411 H,0. C = 66-68 ; H = 4-4.
CjoHgONS requires 0 = 66-98 /h = 4-16 per cent.

The substance melts with profound decomposition at about 250°.

This unsubstituted sulphoxide is converted into the azothionium
base more easily than any of tlie others here described. The change
is instantaneously effected by aqueous mineral acids, and slowly by
hot glacial acetic acid. With concentrated sulphuric acid it gives
a green solution, which turns red on dilution with water.

Phenazothionium Chloi'ide, C^^^^^,^GqS^^JS.^O. — Diphenylamine

ortho-sulphoxide, in quantities of about 1 gram at a time, was shaken
with a freshly prepared solution (15 c.c.) of hydrogen chloride in dry
alcohol. Oare was taken not to allow the temperature to rise above
the ordinary limits. The sulphoxide at once dissolved, the liquid
assuming an intense reddish-brown colour, and in about ten minutes
phenazothionium chloride crystallised from the mother liquor in dark
bx'own needles. These were collected, and, after being washed with
alcohol, were dried for analysis to constant weight in a vacuum over
solid alkali hydroxide :

01013 gave 0-2130 OOg and 0-0331 H.-f). 0 = 57-34; H = 3-63.

When this sample had remained for two days longer under diminished
pressure it was again analysed :

0-1592 gave 0-3338 COg and 00572 Jiff. 0 = 57-19 ; H = 3-99.
Ci2HsNClS,H20 requires 0 = 57-22; H = 3-98 per cent.

When heated at 100° for a short time, this substance is transformed
into a gi^een compound, which is apparently also formed by diluting
the aqueous solution. Alkali hydroxide precipitates this green
substance from an aqueous solution of the chloride. Phenazo-

1266 PYMAN : ISOQUINOLINE DERIVATIVES. PART I.

thionium chloride contains ionisable chlorine, but the salt is not
completely hydrolysed by boiling aqueous sodium carbonate solution.
Other salts of this and similar bases have been previously described
by Kehrmann {Ber., 1901, 34, 4170), who obtained them by the acid
oxidation of thiodiphenylamine derivatives.

The investigation of this rearrangement is being continued with the
object of determining the mechanism of the reaction.

In conclusion, we desire to express our thanks to the Research
Fund Committee of the Chemical Society for a grant which has
defrayed the expense of this research.

The Organic Chemistky Laboratory,

University College,

London.

CXLII. — isoQuinoline Derivatives. Part I. Oxidation
of Laudanosine.

By Frank Lee Pyman.

The alkaloids cotarnine (I) and hydrastinine are particularly in-
teresting, not only on account of their therapeutic value, but also
by reason of their chemical properties, for they are at the same time
secondary amines and benzaldehydes, and form salts derived from
3 : 4-dihydroisoquinolinium hydroxide. They have hitherto been the
only known members of the class they represent, and are produced by
the oxidation of the similarly constituted alkaloids narcotine (II) and
hydrastine respectively together with opianic acid (III) according to
the equation (for cotarnine) :

CHO

COgH
OMe

OMe

OMe

(II.) (I.) (in.)

Cotarnine and hydrastinine may also be prepared by the oxidation of
their reduction products, hydrocotarnine and hydrohydrastinine re-

PYMAN: ISOQUINOLINE DERIVATIVES. PART I. 1267

spectively, of which the former occurs naturally in opium, and this
fact led Freund and Beck {Ber., 1904, 37, 1942) to attempt the
preparation of 2-y8-methylaminoethylbenzaldehyde by the oxidation of
iV-methyltetrahydroi>oquinoline ; this oxidation, however, did not
take place in the desired direction. No other methods of preparing
these or like compounds have hitherto been described, but it is in-
teresting to note that Freund and Beck (Ber., 1904, 37, 3321)
attempted to prepare 6 : 7-dimethoxy-2-methyltetrahydroisoquinoline
(XI), a compound corresponding with hydrocotarnine or hydro-
hydrastiniue, from papaveraldine, but without success.

Now, Decker and Klauser {Ber., 1904, 37, 520) and Decker and

Pschorr {Ber., 1904, 37, 3397) have shown that the JV-sdkjUso-

papaverines (IV) yield on oxidation by means of air in dilute alkaline

solutions dimethoxy-iV^-alkylisoquinolones (V) and veratraldehyde(VI).

CH CH CHO

MeO^\/^CH MeO|^^^^CH ^^

MeOL jv /NR + O2 - MeOL j^ yW "*" I JoMe

C CO OMe

II
CH

JOMe

OMe

(IV.) (V.) (VI.)

It therefore seemed possible that laudanosine (iV^-methyltetrahydro-
papaverine) might behave like narcotine and hydrastine towards
oxidising agents and yield products similar to those furnished by
these alkaloids, and this proved to be the case. Laudanosine (VII)
is readily oxidised by manganese dioxide and sulphuric acid, yielding a
new base, 4 •.5-dimethoxy-2-(S-methyla7ninoethylbenzaldehyde (VIII), and
veratraldehyde.

CH2

Me0|^^/\CH2
CH

CH2

Me0^\/\CH2
MeO^^^ NHMe
CHO

CHO

+ 1 JoMe
OMe

CH^

OMe

OMe
(VII.) (VIII.)

The constitvition of 3 : 4-dimethoxy-2-/3-methylaminoethylbenz-

aldehyde is perfectly clear, since it behaves quite similarly to cotarnine

1268

PYMAN: ISOQUINOLINE DERIVATIVES. PART I.

and hydrastinine ; it is a colourless, crystalline solid, forming primrose
coloured salts of 6 : 1 -dimethoxy-l-Tnethyl-^ : i-dihydroi&oquinolinium
hydroxide (IX) by substitution; when boiled with aqueous sodium
hydroxide, it vmdergoes Cannizzaro's reaction, yielding the anhydrides
of the corresponding acid and alcohol, \'keto-^ : 7 -dimethoxy-2-viethyl-
tetrahydroisoquinoUne (X) and 6 : 7'dimethoxy-2-methyUetrahydroho-
quinoline (XI) respectively.

CH,

CH,

MeO

MeO

MeO
MeO

CH„

MeO
MeO

NMe

CHo

(X.)

(XI.)

Aqueous solutions of its salts yield with aqueous potassium cyanide
a colourless, crystalline compound, \-cyano-^ •.l-dimpAhoxy-l-methyl-
tetrahydro'i&oquinolineiXH), analogous to cyanocotarnine (Freund, Ber.,
1900, 33, 386).

The base forms a condensation product with acetone,* 6ts(4 : 5-c^i-
methoxy-2-p-methylaminoethylbenzylidene)-acetone (XIII), which differs
from the condensation products of cotarnine and hydrastinine with
acetone (Liebermann and Kropf, Ber., 1904, 37, 211) in that two
molecules cf the base take part in it.

MeO

MeO

MeO
MeO

CII./CH
_CH==:CH

(xir.)

, NHMe NHMe-CH2-CHo-

-00-

-CH==CH-l

OMe
OMe

(XIII.)

Bis-(4:5-dimethoxy-2-yS-raethylaminoethylbenzylidene)-acetone forms
a neutral dihydrochloride, which is decomposed by boiling water with
the formation of 6 : 7-dimethoxy-2-methyl-3 : 4-dihydroisoquinolinium
chloride ; on examination, anhydrocotarnineacetone hydrochloride was
found to undergo a similar decomposition.

During the oxidation of laudanosine a considerable quantity of

* It is equally possible that tliis condensation product has the constitution re-
presented by the following formula (compare Liebermann and Kropf, loc. cit. ) :
CH2 CH2

Me0/\/\cH, HoC'^N^^OMe

MeOi

.NMe MeN
CH CH,-CO-CH, UH

OMe

PYMAN: ISOQUINOLINE DERIVATIVES. PART I. 1269

brown, granular matter separates from the solution, and there was
obtained from this a small quantity of a saturated compound,
Ci4Hg(OMe)4. This substance is derived from a hydrocarbon, C^^K^^,
and its formation may possibly be due to the decomposition of
vei'atryl alcohol in a manner somewhat similar to the formation of a
hydrocarbon, G^^B.-^^, from benzyl alcohol (Cannizzaro, Annalen, 1854,
92, 14) or benzyl ethyl ether (Schickler, J. pr. Chem., 1896, [ii], 53,
369).

• The investigation of the products of the oxidation of laudanosine
and other l-benzyl-2-alkyltetrahydroisoquinolines is being continued.

Experimental.

Oxidation of Laudanosine.

Eighty grams of laudanosine were dissolved in a mixture of 160
grams of sulphuric acid and 1-2 litres of water, and mechanically
stirred with 48 grams of pyrolusite containing 80 per cent, of
manganese dioxide for three-quarters of an hour on a steam-bath.
The solution gradually became brown and turbid, and eventually
deposited a brown solid. After cooling, the solution was filtered from
the solid matter {A) and extracted with benzene, which removed the
soluble non-basic constituent {B). The solution was next rendered
alkaline with sodium carbonate, filtered from the precipitated
manganese carbonate, and extracted with benzene ; this removed about
1 gram of yellow oil, which has not yet been fully investigated. The
liquor was rendered strongly alkaline with sodium hydroxide, and
again completely extracted with benzene. The latter was then filtered ^
and extracted with successive small quantities of dilute hydrochloric
acid so long as the latter became neutralised ; these extracts were
combined, rendered faintly acid by the addition of hydrochloric acid,
and evaporated to a thick, brown syrup ; on stirring 'this with dry
acetone, 6 : 7-dimethoxy-2-methyl-3 : 4-dihydro^soquinolinium chloride
separated as a yellow, crystalline powder, which was collected and
washed with acetone ; it amounted to 40 grams. The acetone mother
liquors gave a further quantity of 3 grams of the same compound.
Tlie total yield, 43 grams, represents 63 per cent, of the theoretical.

Isolation of a Compound, Q^^^{0M.q)^,\}1^0, from the Brown Solid " A,"

The amount of air-dried, brown, granular solid was 28 grams. This
was combined with the product from another similar experiment and
worked vip as follows :

Forty-six grams were extracted with ether in a Soxhlet apparatus
for five hours. The ether removed 7 grams of reddish-black, resinous

1270 PYMAN: ISOQUINOLINE DERIVATIVES. PART I.

matter, and deposited also 0'95 gram of a mixture of crystals and
tarry matter. The residue was then extracted with alcohol in a
Soxhlet apparatus for six hours, and the residue concentrated to about
100 c.c, when 2 grams of pale brown crystals were deposited.
Further concentration of the alcohol yielded only brown, amorphous
compounds, which were not further investigated. The crystals
obtained from the alcohol were recrystallised from acetone, and formed
large, oblong, rectangular, colourless plates, which melted at 231°
(corr.). A further quautity of this substance was obtained from the
solids deposited by the ethereal extract :

0-2741, air-dried, lost 0-0085 at 100°. HgO = 3-1.

C\4H8(OMe)4,|H20 requires HoO = 2-9 per cent.

0-1344, dried at 100°, gave 03535 CO^ and 0-0806 HgO. C - 71-7 ;
H = 6-7.

0-2520, dried at 100°, gave 07901 Agl. OMe = 41-4.
Ci^H8(OMe)4 requires C = 71-9 ; H = 6-7 ; OMe = 41-3 per cent.

The molecular weight of this compound was very kindly determined
by Dr. Barger by his microscopic method (Trans., 1904, 85, 286). A
solution containing 0-0682 gram of the compound, dried at 100°, in
1*120 grams of chloroform was intermediate between 0-18 and 0-20
mol. of azobenzene as standard, whence M.W. = 338 — 305, mean 321.
Ci4H8(OMe)4 requires M.W. = 300.

The compound is easily soluble in acetone, chloroform, or pyridine,
fairly readily so in alcohol, but very sparingly soluble in water or the
other usual organic solvents. A chloroform solution of the compound
did not decolorise bromine, nor did an acetone solution immediately
decolorise aqueous permanganate.

Ideyitification of Veratraldehyde.

The non-basic constituent [B) removed from the acid liquor by
benzene was obtained after the removal of the solvent as a dark brown
oil with an odour similar to that of vanillin. On fractionation under
53 mm. pressure, the temperature rose quickly to 195°, and more than
5 grams distilled at 198 — 201° (corr.). On refractionation under
normal pressure, it distilled at 278 — 282°, mainly, however, at
281° (corr.). It solidified on cooling, and melted at 42 — 4.3° (corr.) :

0-1587 gave 0-3796 CO2 and 0-0864 HgO. 0 = 65-2; H = 61.
CgHj^Og requires C = 65-0 ; H = 6-1 per cent.

This substance is therefore veratraldehyde.

4: :5'Dimethoxi/-2-f3-meth7/laminoeihylbenzaldehi/de (VIII, p. 1267).

This base is obtained as an oil, which gradually becomes crystalline,
on the addition of 50 per cent, aqueous sodium hydroxide to the con-

PYMAN: ISOQUINOLINE DERIVATIVES. PART I. 1271

centrated aqueous solution of its hydrochloride. It crystallises from
acetone in prismatic needles, which melt at 123 — 124° (corr.), and is
sparingly soluble in water, giving a solution which is strongly alkaline
to litmus. The base is precipitated from a concentrated aqueous solu-
tion on the addition of concentrated aqueous sodium hydroxide ; it is
easily soluble in alcohol or chloroform, but sparingly so in the other
usual organic solvents. The base decomposes when heated for an hour
at 100°, giving an odour similar to that of methylamine :

0-1530, air-dried, gave 0-3620 CO^ and 0-1038 H^O. C = 64-5 ; H = 7-6.

0-1608 „ „ 8-8 c.c. N2 at 17" and 734 mm. N = 6-l.

I

m C12H17O3N" requires C = 64-5 ; H = 7-7 ; N = 6-3 per cent.

4 : 5-Dimethoxy-2-/5-methylaminoethylbenzaldehyde combines with
acids, forming salts by substitution of the isomeric 6 : 1 -dimethoxy-
2-methyl-3 : 4:-dihydroisoquinoliniu7ti hydroxide (IX, p. 1268).

The chloride crystallises from aqueous solution in a mass of primrose
needles, which contain three and a-half molecular proportions of water
of crystallisation, and melt at 61 — 62° (corr.) to an opaque liquid.
When dried at 100°, this salt melts and decomposes at 186° (corr.).
It is very easily soluble in water or alcohol, giving yellow solutions,
which are neutral to litmus, and show a blue fluorescence when diluted;
it is sparingly soluble in chloroform, and very sparingly so in the other
usual organic solvents :

0-1510, air-dried, gave 0-2629 CO2 and 0-1034 H.3O. C = 47*5; H = 7-7-
T 0-3139 „ „ 0-4710 Agl. OMe=19-8.

0-1116 „ lost 0-0232 at 100°. H2O = 20-8,

CioHio(OMe)2NCl,3^H20 requires 0 = 47-3; H = 7-6; OMe-20-4;
H2O = 20-7 per cent.

0-1429, dried at 100°, gave 0-3115 CO2 and 00849 H2O. C = 59-5;
H = 6-7.

0-1398, dried at 100°, gave 6-8 c.c. ^3 ^^ 1^° and 748 mm. N = 5-6.

0-2141 „ „ 0-1280 AgCl. Cl = 14-6

C12H16O2NCI requires C = 59-6; H = 6-7; N = 5-83 Cl=14-7 percent.

The bromide crystallises from moist acetone in primrose needles,
which contain two molecules of water of crystallisation, and sinter with-
out entirely melting at 87 — 90° (corr.). On drying, the salt becomes
lemon-yellow in colour, and melts at 195° (corr.). The properties of
this salt are similar to those of the chloride :

0 2996, air-dried salt, lost 0-0328 at 110°. H20= 10-9.

Ci2Hic02NBr,2H20 requires H20 = ll-2 per cent.

0-1603, dried at 110°, gave 0-1067 AgBr. Br = 28-3.
Cj2Hjg02NBr requires Br = 27-9 per cent.

The aurichloride crystallises from alcohol in chestnut-brown, serrated
needles, which melt at 169° (corr.). It is anhydrous, and is almost

\

1272 PYMAN : ISOQUlNOLINi^: UERlVATlVES. PART 1.

insoluble in water or cold alcohol, but fairly easily soluble in hot
alcohol :

0-1946 gave 0-0700 Au. Au = 36-0.

CjoHi^O^NCl^Au requires Au = 36'2 per cent.

The picrate crystallises from alcohol in long, yellow, glistening
needles, which melt at 169 — 170° (corr.).

l-Ci/ano-G : l-dimethoxy-2-inethijltetrahydroi&oquinoline (XII, p. 1268).

Ten grams of 6 : 7-dimethoxy-2-methyl-3 : 4-dihydrot«oquinoliDium
chloride were dissolved in 50 c.c. of water, and mixed with a solution
of 3 grams of potassium cyanide in 10 c.c. of water. A sticky,
amorphous mass separated, which soon became hard and crystalline.
The yield was 7*2 grams of nearly pure product, that is, 94 per cent, of
the theoretical.

\-Cyano-Q : 7 -dimethoxy-2-methyUetrahydroisoquinoline crystallises
from moist ether in clusters of colourless, prismatic, glistening rods,
which melt at 127 — 128° (corr.). It is insoluble in water, moderately
easily so in absolute alcohol, but sparingly so in ether :

0-1522 gave 0-3750 CO2 and 0-0964 H.O. C = 67-2; H = 7-l.
C^gHj^O^Ng requires C = 67'2 ; H = 7-0 per cent.

Action of Hot Aqueous Sodium Hydroxide on 4 : 6-Dimethoxy-
2-(B-methylaminoethylbenz(ddehyde. Formation of \-Keto-% : 7-
dimethoxy-%methyltetrahydro\.soquinoline and 6 : 1 ■ Dimethoxy-2-
methylt^Arahydroisoquinoline.

Eighteen grams of 4 : 5-dimethoxy-2-^-methylaminoethylbenz-
aldehyde were mixed with 600 c.c. of 5 per cent, aqueous sodium
hydroxide, and boiled for six hours under a reflux condenser. The
liquid was cooled, exactly neutralised with hydrochloric acid,
evaporated to low bulk, and completely extracted with ether, which
gave on distillation 7-5 grams of crude l-keto-6 : 7-dimethoxy-2-
methyltetrahydrozsoquinoline, melting at 110 — 113°; the liquor was
i-endered alkaline with sodium carbonate, and again extracted with
ether, which gave on distillation 8-0 grams of crude 6 : 7-dimethoxy-
2-methyltetrahydrowoquinoline, melting at 60 — 80° ; on then adding
sodium hydroxide to the liquor and again completely extracting with
ether, only a trace of dark resin was obtained.

l-Keto-6 •.l-dimethoxy-'l-methyltetrahydroisoquinoline (X, p. 1268).

The crude product may be readily purified by recrystallisation from
ether, from which it separates in hard, clear, well defined monoclinic
prism.«, which melt at 126° (corr.). It is easily soluble in water, giving

\

PYMAN: ISOQUINOLIXE DERIVATIVES. PART 1. 1278

a solution only faintly alkaline to litmus, sparingly soluble in cold
etliev or xylene, insoluble in light petroleum, and very readily soluble
in the other usual organic solvents. It has very weak basic properties,
and can be extracted from a solution in a large volume of benzene by
means of concentrated hydrochloric acid, bub not by dilute acids :

0-1696 gave 0 4052 COg and 0-1027 H,0. C = 65-l ; H = 6-8.

0-1486 „ 8-7 c.c. Ng'at 19° and 736 mm. N = 6-5.

0-2105 „ 0-4408 Agl. OMe = 27-7.
C12H1AN requires C = 65-l ; H = 6-9 ; N = 6-3; OMe = 28-l per cent.

6 •.7-Diniethoxi/-'2-methijltetrahydroiaoquinoline (XI, p. 1268).

The crude base is purified by crystallisation of the hydrochloride,
regeneration from the pure salt, and crystallisation from light
petroleum. It separates from this solvent in clusters of white needles,
■which contain one-half a molecular proportion of water of crystallisa-
tion and melt at 83 — 84° (corr.). This base is somewhat sparingly
soluble in cold water, and very sparingly .so in hot water, so that
it separates as an oil on warming a cold saturated aqueous solution ;
it is moderately easily soluble in light petroleum, and very easily so in
the other usual organic .solvents :

0-1826, air-dried, lost 00071 in a vacuuin over HoSO^. 1100 = 3-9.

C^oHjyOgN.IH.^O requires H20 = 4-2 per cent.
0-1582, dried in a vacuum, gave 0-4031 CO.^ and 0-1175 H./).

C = 69-5; H = 8-3.
0-1251, dried in a vacuum, gave 7-1 c.c. Ng at 18° and 766 mm N= 6-7.

OjgHjyOgN requires C = 69-5 ; H = 8-3 ; N = 6 8 per cent.
The hydrochluride crystallises from moist ethyl acrtate in clusters of
white, feathery needles, which melt at 216 — 2 17° (corr.) and contain n^-arly
one and a-half molecular proportions of water of crystalli.-atiou. When
this salt is moistened with water, it assumes a pale yellow colour, and
crystallises fi-om moist acetone in pale yellow needles, which melt at
59 — 60° (corr.) and contain three molecules of water of crystallisation;
after drying, first in a vacuum desiccator over sulphuric acid and then
at 100°, this salt becomes colourless, and melts at 216 — 217° (corr.).
It is easily soluble in water or alcohol, moderately easily so in
chloroform, sparingly so in acetone or hot ethyl acetate, and insoluble
in ether, benzene, or light petroleum :

0-2109, air-dried salt (fi-om moist ethyl acetate), lost 00186 at 100°.

H.p = 8-8.
0-2681, air-dried salt (from moist acetone), lost 0-0483 at 100°.
H2O=180.

Ci2Hi70oN,HCl,liH20 requires H.p = 9-9 per cent,
Ci2Hi702N,HCl,3H20 ,, H20=18-2 „
VOL. xcv. 4 o

1274 PYMAN : ISOQUINOLINE DERIVATIVES. PART I.

0-1521, dried at 100°, gave 0-3275 CO^ and 0-1007 H.,0. C = 58-7 ;

H = 7-4.
0-1619, dried at 100°, gave 00946 AgCl. 01 = 145.

CioHj-OoN.HCl requires 0 = 59-1 ; H = 7-5 ; 01 = 14-6 per cent.
The auricMoride crystallises from absolute alcohol in deep orangej
diamond-shaped plates, many of which have the obtuse angles rounded
off, and melts at 147° (corr.). It is anhydrous, and is sparingly
soluble in water and alcohol :

0-1627 gave 0-0585 Au. Au = 36-0.

OjoHjgO^NOl^Au requires Au = 36-0 per cent.
The picrate crystallises from absolute alcohol in broad, yellow
needles, which melt at 159 — 160° (corr.).

£is(4: : b-Dimethoxij-2-li-methylaminoethylbenzylidene)-acetone
(XIII, p. 1268).

Two grams of 6 : 7-dimethoxy-2-methyl-3 : 4-dihydrotsoquinolinium
chloride were dissolved in 20 c.c. of water, and 20 c.c. of 10 per cent,
aqueous sodium hydroxide were added. To the clear solution 1 c.c. of
acetone was added. The solution remained bright for about a minute,
and then suddenly began to deposit oil. After several hours, the
deposit, which had become crystalline, was collected, washed with
cold water, and dried. The yield amounted to 0-65 gram, that is,
37 per cent, of the theoretical.

Bis{\ : 5-Dimethoxy-2-/3-inethylaminoethylbenzylidene)-acetone cryatal-
lises from moist ether in long, white, glistening needles, which contain
four molecules of water of crystallisation, and melt at 77° (corr.) after
softening at 75°; after dehydration in a vacuum desiccator over
sulphuric acid, it loses water and becomes amorphous, and on then
adding to it absolute ether, the base momentarily dissolves, and
immediately separates again in colourless, prismatic needles, which are
anhydrous and melt at 107 — 108° (corr.).

Both the hydrated and anhydrous varieties are stable in moist air.
The base is very sparingly soluble in water or light petroleum,
and sparingly so in ether, but easily soluble in the other usual
organic solvents. It decomposes on prolonged heating at 100° :

0-1535 hydrated base gave 0-3392 OOg and 0-1119 H,0. 0 = 60-3;
H = 8-2.

0-1609 hydrated hase gave 7-1 c.c. Ng at 16° and 762 mm. N = 52.

0-2650 ,, „ lost 0-0356 in a vacuum over H2SO4.

H20=13-4.
<^2i^3fPo^v'^i^2^ requires 0 = 60-0; H = 8-2; N = 5-2; H20=13-3

per cent.

MORPHOTROPIC RELATIONSHIPS, ETC. 1275

0-1593 anhydrous base gave 0'4043 OO2 and 01093 H.,0. C = 69'2 ;
H = 7-7.

0'1524: auhydious base gave 7'G c.c. N., at 15 and 768 mm. N = 5"9.
CgyHggOgNg requires 0 - 09 -2 ; II = 7-8 ; N = 60 per cent.

Molecular-weight determination by the cryoscopic method :

0-1225 in 18-81 benzene gave A« - 0-072. M.W. = 443.

0-2822 „ 18-81 „ „ A«- 0-171. M.W. -430.

C.^HsgO^N, requires M.W. = 468.

The dihydrochloride crystallises from water in colourless prisms,
which contain three molecules of-^^water of crystallisation, and decompose
at about 188° (corr.). It is sparingly soluble in cold water, giving a
neutral solution, and very sparingly so in alcohol :

0-1712,air-dried,gave0-3419 CO2 and 0-1139 H.p. C = 54-5; H = 7-5.

0-1143 „ „ 4-3 c.c. No at 16° and 767 mm. N = 4-4,

0-562G „ lost 0-0497 at 100°. HoO = 8-8.

C27H3605N2,2HC1,3H20 requires C = 54'-4; H = 7-5; N = 4-7;
HoO = 9-1 per cent.

01509, dried at 100°, gave 0-3315 CO., and 0-0941 H.,0. C = 59-9 ;
H = 7-0.

0-1361, dried at 100°, gave 0-0725 AgCl. CI = 13-2.

C27H36O5N2, 2 H CI requires C = 59-9; H = 7-l; CI = 13-1 percent.

This salt dissolves in cold water, giving a colourless solution, which
becomes turbid on the addition of aqueous sodium carbonate, owing to
the separation of the corresponding base. If, however, the aqueous
solution of the hydrochloride is warmed, it quickly becomes yellow,
and, after heating for some time, the addition of aqueous sodium
carbonate no longer causes turbidity ; on then evaporating the
solution, the residue is found to be pure 6 : 7-dimethoxy-2-methyl-3 : 4-
dihydi'oi'soquinolinium chloride.

Wellcome Chemical Work.s,
D.\RTFOK]i, Kent.

CXLIII. — The Morpliotropic Relationshi2:^s hetiveen the
Derivatives of Picric Acid.

By George Jerusalem.

The work done during recent years by Barlow and Pope (Trans., 190G,
89, 1675; 1907, 91, 1150; 1908, 93, 1528) furnishes a method for
investigating crystal structure which has led to the solution, in general

4 o 2

1276 JERUSALEM: THE MORPHOTROPIC RELATIONSHIPS

terms, of the problem involved in the relation between crystalline
form and chemical composition and constitution, and to its practically
complete solution in a large number of specific cases. The application
of the new method of treatment leads to the conclusion that, in any
particular crystalline substance, each atom appropriates to its own
occupation an amount of space approximately pi"oportional to the
lowest or fundamental valency of the element concerned. The clue
thus provided to the volume signification of valency led Le Bas (Trans.,
1907, 91, 112; Phil. Mag., 1907, [vi], 14, 324; 1908, [vi], 16, 60)
to a rigid proof that in liquid organic substances the same relation
holds between atomic volume and valency.

Le Bas showed that the atomic volumes of carbon and hydrogen are in
the ratio of four to one in the higher normal paraffins, and that on com-
paring a number of members of the series under corresponding tempera-
ture conditions, the atomic volume of either element remains constant
throughout the series. No method has been yet devised for directly
determining what are corresponding temperatures for a series of solid
crystalline substances, but Barlow and Pope's results indicate that
such temperatures would be those at which the molecular volumes, V,
are directly proportional to the sum of the valencies of the atoms
composing the molecule, the so-called valency volume, W.

In their comparison of the crystalline forms of related substances,
these authors therefore calculated the so-called equivalence parameters,
x'.y '.z, as the dimensions of a parallelepipedon having the volume, W,
and the relative lengths of sides given by the crystallographic axial
ratios. A series of sets of equivalence parameters may thus be
calculated for a series of related substances which indicates, under
corresponding conditions, the morphotropic effect of the chemical
substitutions which convert the various substances one into the other.

The melting points — which are approximately corresponding tem-
peratures— of the normal paraffins containing from 11 to 35 atorns of
carbon in th^ molecule only change progressively from —26*5° to
-h74"7° ; there appears hence but little reason to anticipate that, in a
series of very closely related substances containing the same elements
in not widely differing proportions, corresponding temperatures would
differ very greatly.

If the Barlow-Pope conclusion concerning the relation between
valency and volume be correct, it would thus be expected that an
approximate proportionality would exist between the molecular
volumes, determined at the same temperature, and the valency
volumes of a series of such closely related compounds as the picrates
and sbyphnates of organic bases. A new and independent method of
testing the accuracy of the conclusion as to the proportionality of
valency and volume is thus rendered available, and is applied in the

BETWEEN THE DERIVATIVES OF PICRIC ACID. 1277

present paper. The molecular volumes of a number of picrates and
styphnates of organic bases have been determined, and it is shown
that the ratio, VjW^R, of the molecular and the valency volumes
does not vary by more than + or - 4 per cent. A confirmation is
thus provided of the law of valency volumes.

From a study of the crystalline forms exliibiteil by aromatic
substances, Barlow and Pope derived a very important conclusion
concerning the disposition of the component atoms in the crystal
structures assumed by benzene and large numbers of its derivatives ;
this conclusion is to the effect that in the crystal structures of benzene
and many of its derivatives the carbon atoms are arranged in columns
throughout the crystalline material. The spheres of influence, within
which are situated the carbon atoms, are arranged in sets of three in
triangular contact, and such sets of three are packed one upon the
other so as to form the continuous columns described (Trans., 1906,
89, 1693). In crystalline benzene these columns of carbon spheres
are packed together in such a manner that just sufficient space is left
for the accommodation of the requisite proportion of hydrogen spheres
of atomic influence to make up the molecular composition of benzene ;
in the crystalline derivatives of benzene the columns of carbon spheres
are pushed apart to an extent svifficient to allow of the introduction of
the substituting groups, but the continuity of the carbon columns is
not broken.

As previously indicated {Proc. Roy. Soc, 1908, 80, A, 557), a direct
method can be devised of testing the validity of the conclusions as to
the existence of these columns of carbon spheres. That equivalence
parameter which measures the height of two links or layers in the
carbon column measui-es the height of the benzene molecule on a scale
obtained by taking the volume of a univalent sphere of atomic
influence as unity; if the carbon columns remain unbroken in the
derivatives of benzene, the particular equivalence parameter referred
to must recur amongst the equivalence parameters of all such
derivatives. Of the equivalence parameters of benzene, x: y :z =
3-101 : 3-480 : 2-780, the third, 2 = 2-780, represents the lengths of two
links in the carbon column. It has been already shown that a value
approximating closely to this occurs among the equivalence parameters
of a number of dei-ivatives of pici-ic acid, and since these substances
lend themselves readily to crystallographic measurement, I have
pi-epared and measured a large number of them, the results being
recorded in the present paper.

The close-packed assemblage representing benzene itself, to which
reference has just been made, is termed the hexagonal benzene
assemblage (H) in allusion to its mode of derivation. Another, which
Barlow and Pope traced amongst certain benzene derivatives, is termed,

1278 JERUSALEM: THE MORPHOTROPIC RELATIONSHIPS

for similar reasons, the rhombohedral benzene assemblage (R) ; it differs
dimeusionally from the hexagonal one in that its z value is rather
smaller than that of the latter, and also because in certain cases it
may lead to pseudo-cubic crystal structures (C) in which the identity
of the s value becomes lost. It will be shown that all the aromatic
substances dealt with in the present paper possess equivalence para-
meters identifying them with one or other of these three types

In the following descriptions the crystalline system and axial ratios
are stated, together with the valency volume, W, and the equivalence
parameters and molecular distance ratios, ;( : i/' : w. The latter values
are calculated from the densities, d, determined on the crystalline
materials. For the purpose of demonstrating the fact that the mole-
cular volumes, V, are nearly proportional to the valency volume, W,
the quantity, E= V/W, which should be constant if the proportionality
were exact, is also stated. The densities were determined by measur-
ing the density of mixtures of a light and a heavy liquid of the same
density as the crystals immersed in them ; as for the present purpose
it is only necessary to determine the densities with an accuracy of
about one part in a thousand, it is superfluous to state the details of
the determination in each case.

Ammonium Picrate.

Crystal system : Orthorhombic {Proc, Boy. Soc, 1908, 80, A, 557) :

a -.b : c = 1-8914 : 1 : 1-3871.

a; : w : ;: = 5-251 : 2-776 : 3-58-2. JV=56. R = 2-5o7.

X:^:a'= 7-174 : 3-794 : 5-262. fZ = l-719. ^=143-2.

The substance is of the hexagonal type (//), and its y value
approximates to the value, s = 2-780, of benzene.

Picric Acid.

Crystal system : Orthorhombic (Brugnatelli, Zeitsch. Krtjst. Min.^
1905, 40, 360) :

a:h -.c = 1-0305 : 1 : r0434. Jr=50. /.' = 2-594.

x:y:z = 3-706 : 3-596 : 3-752.

x: il-: CO = 5-094 : 4-941 : 5-153. rf = l-767. ^=129-7.

Styphnic Acid {Proc. Roy. Soc, 1908, 80, A, 562).

Crystal system : Hexagonal ; a : c = 1 : 1-3890.

On referring this axial ratio to orthorhombic axes, the following
values result :

a -.h : c ^ I -7321
X -.y : z = 4 -825
X'. '<\i : o) = 6-615

1 : 1-3890.

2-786:3-869. /r=52. Ji=:2-577.

3-819.-5-305. (^:=l-8-29. ^=134-1.

BETWEEN THE DERIVATIVES OF PICRIC ACID.

1279

The substance is of the hexagonal type (//), and its y value
approximates to the value, 2 = 2'780, of benzene.

Monomethylamine Picrate.

This salt was prepared by Delepine {Ann. Chim. Phys., 1896, [vii],
8, 461) and Ristenpart (Ber., 189G, 29, 2530). It crystallises from
ethyl acetate in large, straw-yellow crystals melting at 215°.

Crystal system : Orthorhombic ; a :b : c = 2"3361 : 1 : 1'1529.

Forms observed : a{100j, c[001!, r{lO\}, o{lll{.

The following angular measurements were obtained :

Limits.
63°34'— 64° 9'
71 53— 72 17
45 44— 46 19
51 15— 51 37
25 41 — 26 37
35 45— 35 54

Before calculating the following values, the axial dimension a was
divided by two :

Number of

Angle.

observations.

100 : 101

26

100 : 111

24

101 : 111

20

001 : 111

20

101 : 001

14

111 : 111

9

Mean.

Calculated

63°44' 0"

—

72 4 50

—

45 56 40

4.5°57'10"

51 26 30

51 25 50

26 18 40

26 16 0

35 50 0

35 50 20

X : y

z = 4186
CO = 5'672

3-584
4-857

4-132.
5-599.

JV=62. ^ = 2-488.
d=l-Q87. F=l54.-2.

The close approximation of the y value for monomethylamine
picrate to that of picric acid indicates that this substance is of the
pseudo-cubic type (C) ; its equivalence parameters and molecular
distance ratios are very closely related to those of picric acid. The
form a{100} is much the largest, and the other forms are well
developed.

Dimethylamine Picrate.

This substance was also prepared by Delepine (loc. eit., 459), and
separates from alcohol or dilute acetone in straw-yellow ciystals
melting at 158—159°.

Crystal system : Orthorhombic ;a:h : c= 1'9222 : 1 :^0-90049.

Forms: «{100}, r{101j, o'lll}, w;{211j, 6{010}.
The following measurements were obtained ;

Number

of

Angle.

observations.

Limits.

Mean.

Calculated.

100 ;

; 111

32

70°36'— 70°57'

70°48'20"

—

010 :

: 111

20

50 38 — 50 53

50 48 20

—

100 ;

; 101

15

64 48 — 64 56

64 53 10

64°53'50"

100 :

: 211

11

55 2—55 18

55 9 30

55 9 10

010 :

: 211

12

56 27 — 56 56

56 41 40

56 41 20

111 :

; 111

10

38 19 — 38 29

38 21 20

38 23 20

111 :

: 101

12

39 7—39 16

39 11 40

39 11 40

The form a{100} is always dominant ; w{2ll} is very rarely seen on
crystals from alcohol, but is always present on those from dilute

1280 JERUSALEM: THE MORPHOTROPIC RELATIONSHIPS

acetone. No distinct cleavage is observed. After multiplying the
unit length along the axis c by two, the following values of equivalence
parameters and molecular distance ratios are obtained :

X :y -.z = 5-186 : 2-698 : 4-859. JF=6S.
X:^:o)= 7-15-2 : 3-721 : 6 70-2. r= 178-4.
rf = 1-538. 72 = 2-622.

The substance therefoi-e belongs to the hexagonal type of marshal-
ling (//), and both sets of parameters approximate very closely to the
corresponding values quoted for ammonium picrate. The y values
of the dimethylamine and the ammonium and potassium salts are
almost identical, namely :

Potassium Salt :—x :y:z = 5-082 : 2-698 : 3-647 {Proc. Roy. Soc,
1908, 80,^, 560).

A distinct morphotropic relationship is apparent between mono- and

di-methylamine picrate ; this is expressed in the following statement

of fundamental angles :

JIoMomi-thyl- Dimethyl-
Angle, amine piciatu. amine pi. rate.
100 : 101 63°44' 0" 64^53'50"

100 : 111 72 4 50 70 48 20

101 : 111 45 57 10 49 11 40

Elhylamine Picrate.

This salt was prepared by Smolka (Afonatsh., 1885, 6, 917) and
melts at 170°. Large, straw-yellow crystals are deposited from
ethyl acetate solutions.

Crystal system : Monosymmetinc ; a : b : c = 2-2768 : 1 : 1-5350 ;
)3=92°27'20".

Forms: a{!00}, c{'>01}, o'lll}, r{101j, r'{10T}, w{lU}, p{2\0}.

The following angular measurements were obtained :

Number of

An

?le.

observations.

Limits.

Mean.

Calculated.

100

001

16

87°10'— 87°46'

87°32'40"

—

001

101

18

34 26 — 34 53

34 44 40

101

111

17

52 7 - 52 36

52 22 50

001

111

19

59 41 — 60 17

59 55 20

59^53'50"

101

111

9

51 12— 51 26

51 18 20

51 16 30

100

111

13

70 40— 71 16

70 59 20

70 58 10

001

101

4

32 57 — 33 17

33 10 0

33 12 40

100

101

3

54 19— 54 21

54 19 40

54 20 0

001

111

8

58 18 — 58 34

58 25 20

58 26 20

100

001

13

92 12 — 92 43

92 26 50

92 27 20

101

100

10

57 27 — 57 56

57 40 20

57 40 40

111

111

6

40 14 — 40 30

40 23 50

40 25 20

100

210

2

48 7—48 20

48 16

48 40 40

No distinct cleavage plane is observed, and />{210} is rare and

always very small. The following values were obtained :

x:y:z = 6-126 : 2-691 : 4-130. r,_a.o^y^r.„
X : t/' : w = 8-324 : 3656 : 5-611. '^"^'^ '^' ^" •

;F=68 . r=170-6. <e = l-608, 22 = 2-509.

BETWEEN THE DERIVATIVES OF I'lCltlC ACID. 1281

The y value is practically identical with that of the isomeric
dimethylamine picrate, for which

x\y\z ^ 5-186 : 2-098 : 4-859,
and in the passage from ammonium picrate, with
k:ij:z = 5-251 : 2-776 : 3-852,
to dimethylamine picrate the main increase falls upon the parameter
X ; in passing to ethylamine picrate, the x parameter of the
ammonium salt suffers the largest increase.

As the factor R is nearly constant throughout the series of salts
now considered, the same relationships are exhibited in this and in
the following cases by the molecular distance ratios as by the
equivalence parameters.

Triethylamine Picrate, Et3N,C,.H2(N02)3'OH.

This salt has not been previously described, and was prepared by
mixing hot aqueous solutions of triethylamine hydrochloride and
calcium picrate and allowing to cool. Triethylamine picrate, being
sparingly soluble in cold water, separates, and is purified by crystal-
li!?ation from hot alcohol; it melts at 173°, and is very soluble
in ethyl acetate or acetone, giving solutions from which bright straw-
yellow crystals are deposited :

0-1355 gave 20-2 c.c. N., (moist) at 17° and 764 mm. N = 17*31.
CjgHjgO^N^ requires N = 1700 per cent.

Crystal system : Orthorhombic ; a : 6 : c = 2-9752 : 1 : 1-5751.

Forms observed: a{10U], r{101j, c'OOl}, i»{210}, ^{Oll}, ?'{021},
S'OlOj.

The followinor angular measurements were obtained :

I

Number of

An

gle.

observations.

Limits.

Mean.

Calculated,

100

: 101

24

61"57i'— 62°20'

62° 6'10"

—

001

: Oil

25

57 25 — 57 42

57 35 20

—

210

: 100

17

55 55 — 56 19

56 4 50

56° 5'20"

021

: 001

7

72 14 — 72 35

72 27 20

72 23 20

Oil

: 101

8

61 38 — 61 45

61 42 30

61 43 30

Oil

: 210

11

45 27 — 45 34

45 30 50

45 31 10

101

:001

14

27 29 — 28 2

27 51 40

27 53 50

The form a{100J is dominant, §''{021} is very small, and 6(010} was
only observed in one instance ; there is a poor cleavage on c{001} :

x'.y.z = 8-026 : 2-698 : 4-249.
X : 4/ : ft» =11-030 : 3-708 : 5840.

rF=92. r=238-8. rf = l-383. J? = 2-596.

The introduction of a second and third ethyl group into mono-

ethylamine picrate has thus been accompanied by a large increase in

the parameter x, that of y has remained pi-actically unchanged, and

that of z has increased very slightly.

1282 JERUSALEM: THE MORPHOTROPIC RELATIONSHIPS

Tetraethylammonium Picrate, Q^.^i^O^^'O^^t^.

This salt was first prepared by Lessen {Aniialen, 1876, 181, 375),
who gives the melting point as 249 — 251° ; the material now examined
melted at 254°. Very good, although small, orange-coloured crystals
are obtained from ethyl acetate solutions.

Crystal system : Monosymmetric ; a\h \ c = 2-9909 : 1 : 1"6075 ;
/8 = 92°55'20".

Forms observed : a'lOO], r{101}, /{lOT}, m{210!, ojlll}, w{\\\].

The following angular measurements were obtained :

Number of

ADgle. observations. Limits. Mean. Calculated.

100 : 101 27 59°12' — 59°37' 59''29'40" —

100 : 101 25 63 52 — 64 10 64 1 40 —

210:100 24 55 53 —56 22 56 1140 —

111:101 19 53 57i— 54 22 54 9 30 54°10'10"

111:101 9 55 0 — 55 23i 55 1140 55 1910

101:111 9 70 55 —7113"' 71 3 40 71 8 20

101:210 10 75 43 — 76 2 75 53 0 75 53 40

101:210 7 73 24 —73 44 73 32 50 73 35 40

101:11] 6 7121 —7152 714150 714110

111:210 7 34 38 — 35 2 34 45 50 34 43 10

101:101 26 56 14 —56 42 56 28 10 56 28 40

The form c{001} is dominant, whilst o{lll} and t«{lll} are, in
general, small. It is noteworthy that, with the exception of the
pinacoid c{001}, the same forms are observed as on monoethylamine
picrate :

x:y:z - 8-337 : 2-788 : 4-481. o_q2°oV20"
X--^ -.o =11-277 : 3-769 : 6-063. P-^^^^^^ ■

TF^lOi. r=257-3. 72=2-474. d^lSQB.

The parameter y is slightly larger than in the case of mono- and
tri-ethylamine picrates, but the main increase in the valency volume
is still borne by the parameter x ; the morphotropic relationship thus
involved is shown in the close similarity of the observed angles in the
zones [010] and [001] on the two substances:

Triethyl- Tetraethyl-

Angle. amine salt. ammonium salt.

100 : 101 62° 6'10" 59°29'40"

101 : 101 55 47 40 56 28 40
100 : 210 56 5 20 56 1140

Aniline Picrate.

Large measurable crystals of this substance are obtained from
alcohol; they are of a dark green colour, and give measurements
identical with those made on red crystals which are deposited from
aqueous solutions.

Crystal system : Monosymmetric ; a \h •.c = 3-7120 : 1 : 2-1048 j
/3 = 92°47'50".

BETWEEN THE DERIVATIVES OF PICRIC ACID. 1288

Forms observed: «{100}, c'OOl}, w{011J, r[101j, r'{10T}, p{20l\.
The followinjj anfjular measurements were obtained :

Number of

An

gle.

obse

•vatious.

Limits.

]\Iean.

Calculated

100

001

17

86°50' — 87°36'

87'12'10"

001

101

14

29 58 — 30 23

30 13 10

—

001

: Oil

22

64 6—64 53

64 33 40

—

001

: 101

7

28 43i— 29 19

28 54 0

28°51'30"

100

: 101

6

57 56" — 58 33

58 19 0

58 20 30

101

Oil

5

68 1—68 28

68 11 10

68 12 40

100

:011

10

88 30—89 0

88 44 10

88 47 55

101

: 201

3

19 16 — 19 34

19 24 0

19 57 10

100

: 001

15

92 22J — 92 57

92 47 0

92 47 50

Oil

Oil

7

50 40 — 51 20

50 52 50

50 52 40

y

Z :=

5-163

2-782 :

5-855.

^

00 —

6 973

3-757 :

7-909.

IV

= 84.

r= 207-0. d

= 1-558.

The forms a{100}, c{001}, n{OU} are equally well developed ; ??{201}
is only present on the red crystals from water. There is a perfect
cleavage parallel to «{100}. After dividing unit length along the
axis c by two, the following values are obtained :

3 = 92°47'50".
72=2-464.

On comparing the equivalence parameters first stated with the
values for ammonium picrate,

X :y iz = 5-251 : 2-776 : 3-852,

it is seen that the value x is only slightly different, and that the value
y has remained .the same within the eri'ors of measurement, and is the
same as the z value for the hexagonal benzene assemblage {H). The
result of the introduction of a phenyl group into ammonium picrate is
therefore morphotropically very simple.

Besides the above-quoted piciates, a large number of others were
crystallised from different solvents, but could not be obtained in
measurable crystals, or were anorthic and thus of no immediate value
for our present purpose. When it was possible to obtain large
crystals, the densities were determined in order to test the constancy
of the quantity B. The following salts were thus examined.

Be7izylamine Picrate, CH2Ph'NH2,CgH2(N02)3'OH,

has been described by Moureu and Lazennec {ComiJt.rend., 1906, 143,
553). It was prepared by adding benzylamine to a solution of an
equivalent amount of picric acid in boiling water. After cry.stallisa-
tion from hot alcohol, it melts at 195 — 199° :

0-1740 gave 24-9 c.c. Ng (moist) at 16-5° and 766 mm. N = 16-69.

CjgHjgOYN^ requires N= 16*66 per cent.
Anorthic crystals are deposited from ethyl acetate solutions.
/F=90. r=218-9. f^=l-536. 72 = 2-433.

1284 JERUSALEM: THE MOKPHO'l'UOPlO RELATIONSHIPS

0-Toluidine Picrate, C6H^Me-NH2,CcH2(N02)3-OH,

was described by Cari'asco and Padoa (Aiti B. Accad. Lincei, 1906,
[v], 15, i, 699). It was prepared in a similar way to the foregoing
compound, and is also nearly insoluble in water. After crystallisation
from alcohol, it melts and decomposes at 212 — 215*^ :

0-2481 gave 36'1 c.c. R, (moist) at 18° and 762 mm. N= 16-85.

CjgHjoO-N^ requires N = 16-66 per cent.
Badly developed, monoclinic crystals are deposited from alcoholic
solutions :

1F=90. r=218-5. rf = l-539. T. = 2-i2S.

vOi-Toluidine Picrate.

This salt was prepared and purified in a similar way to the above

mentioned. It decomposed when lieated above 180° :

0-1400 gave 20-1 c.c. N.^ (moist) at 17° and 764 mm. N = 16-75.

CjjHjoOkN^ requires N= 16-66 per cent.

Striated, monoclinic crystals are obtained by crystallisation from

cold alcohol :

W=m. r=22,5-6. fZ= 1-491. ii = 2-506.

For the sake of comparison, the equivalence parameter of naphtha-
lene picrate {Atti Soc. Itcd. sci. nat., 1902, 41, 15) and of the additive
compound of naphthalene and trinitrobenzene (E. Accad. sci.
Bologna, Sessione del 10 Novembre 1907), both of which were
measured by Boeris, may be stated here. The axial ratios of these
substances are :

CjoH8,C6H2(NO.,)3'OH. C,oH8,C6H3(N02)3.

a -.b -.c = 2-&582 : 1 : 4-1846. _ a : b : c = 2-3170 : 1 : 4-0961.

/3 = 83°12'. )3 = 83'24',

After dividing unit length along the axis c by two, the following
equivalence parameters are obtained :

CjoH8,C6H2(NOo)3-OH. CioH8,CeH3(N02)3.

/r=98. JV^96.

x:y:z = 6-401 : 2-715 : 5-680. x : y : z = 6-327 : 2-731 : 5-593.
j3 = 96°48'. /8 = 96°36'

The following values for naphthalene picrate wex-e found by
determining its density :

r=233-5. c?=l-580. ^ = 2-382.

X-.yf'-.o = 8-549 : 3-625 : 7-586.

;3 = 96°48'.

The value y is again very near the z value for the hexagonal benzene
as.semblage (//), and both x and z have increased considerably in
comparison with the corresponding dimensions for ammonium picrate.

BETWEEN THE DERIVATIVES OF PICRIC ACID. 1285

MonomethTjlainine Styphnale, NH2Me,C^H(OH).,(NO.,)3.

This salt is obtained by mixing equivalent amounts of monocaleium
styphnate and methylamine hydrochloride in hot aqueous solution and
evaporating ; it separates as a bright yellow, crystalline powder, and is
purified by crystallisation from alcohol. The salt melts at 191°, is
very soluble in acetone, and moderately so in water or alcohol ; good
crystals for goniometric measurements are obtained with diflSculty,
but fairly satisfactory ones were deposited from solutions in ethyl
acetate, the salt being rather less soluble in this than in the other
solvents mentioned.

The base distilled from O'SIOO gram, after addition of lime and
water, neutralised 11 •■45 c.c. of sulphuric acid containing 0'04907 gram
per c.c. :

MeNH2 = ll-49.

C-HgOgN^ requires MeNH2= 11-26 per cent.

Crystal system: Monosymmetric ; « : 5 : c = 0"5232 : 1 : 0'3716 ;
^=103°4'10".

Forms observed : 6(010}, c{001}, p{110}, ^{Oll}.
The following angular measurements were obtained :

Number of

Angle.

observations

Limits.

Mean.

Calcukted.

010 i on

13

69°50'— 70°21'

70° 6' 0"

__

010 : 110

14

62 36 — 63 26

62 59 40

— .

001 : no

16

78 5— 78 43

78 22 40

— .

001 : Oil

9

19 41—20 8

19 56 30

19°54' 0"

110 : 110

14

101 17 —101 55

101 33 40

101 37 20

The form ^{Oll} was but rarely ob.^erved, and was always very
small; there is a perfect cleavage parallel top{110}, and the faces of
all the forms give multiple reflections on the goniometer. After
dividing unit length along the axis b by four, the following values
are obtained :

X :•>!':« = / 904 : 3'/ /7 : 5 614.

?r=64. r=163-2. rf^l-692. i2 = 2'551.

The equivalence parameter y has nearly the same value as in the
case of ammonium picrate, namely, 2'776 ; close correspondence
between the molecular distance pai'ameters, i/', is also to be noted, the
values being respectively 3'777 and 3*794.

Dimethylamine Styjjhnate, NHMe2,CgH(OH)._,(NOo)3.

The preparation of this salt is similar to that of the previous one,
and yields a bright yellow, crystalline substance, which melts at 208°

128G JERUSALEM : IHE MORPHOTROPIC RELATIONSHIPS

after crystallisation from alcohol. The salt is sparingly soluble in
water, dissolves more readily in alcohol, and still more easily in
acetone and ethyl acetate :

0-2072 gave 34-3 c.c. Ng (moist) at 16'" and 770 mm. N= 19-57.
CgHjoOgN^ requires N= 19*31 per cent.

Measurable crystals were obtained from acetone solutions.

Crystal system : Monosymmetric ; a:h:c = 1-5897 : 1 : 1-2606 ;
^ = 68°5'10".

Forms observed: a{100}, m{110}, ?{011}, cJOOlj.

The following: anfrular measurements were obtained :

Number

ot

All

gle.

obsei

•vations.

Limits.

Mean.

Calculated.

110

100

27

55°31'— 56° 7'

55°51'40"

—

100

■ Oil

19

75 43— 76 19

75 57 50

—

Oil

Oil

15

98 38 — 99 14

98 55 50

—

100

001

2

68 16 — 68 23

68 19 0

68° 5 '10"

110

Oil

13

39 44 — 40 10

39 53 30

40 5 0

110

Oil

9

60 24 — 60 37

60 30 0

60 28 10

Oil

001

8

49 14 — 49 44

49 30 40

49 28 0

110

110

13

68 0—68 39

68 14 10

68 16 40

The axial ratios of this salt show clearly that this is pseudo-
hexagonal, and it is therefore convenient to change the indices
of the forms present so that the axial directions become pseudo-
rectangular. This may be done by changing the indices 100, 001,
110, on respectively to 100, lOT, 210, OIL The axial ratios then

become

a:b:c = 2-9503 : 1 : 1-2606.
i8 = 91°26'20".

Whence the following values are calculated :

X : tj -.z = 7-849 : 2-660 : 3-354. fl_qio.,f.,.^»
X:^- CO =10-836 : 3-673 : 4*632. ^"^'^ "^^ "^ *

?F=70. r= 184-3. rf = 1-575. i,; = 2-633.

Trimethylamine Styphnate, NMe3,C(.H(OH)2(N02)3.

This salt was obtained in the same way as the preceding one, and is
sparingly soluble in alcohol, more so in acetone, and almost insoluble in
ethyl acetate. After purification by crystallisation from acetone solu-
tion, it forms a bright yellow, crystalline powder, which decomposes
gradually on heating to above 200° :

0-1492 gave 23-9 c.c Ng (moist) at 14° and 752 mm. N= 18-72.
CgHjgOgN^ requires N = 18-42 per cent.

Small but, in some zones, very brilliant crystals are obtained from
acetone solution.

Crystal sy.stem : Orthorhombic ; a:h:c = 2-9160 : 1 : 1-3494.

Forms observed : aJlOO}, r{101}, ^{210}, ^{011}.

BETWEEN THE DERIVATIVES OF PICRIC ACID. 1287

The following anjrular measurements were obtained :

Nuiubcr of

All

kIc.

observations.

Limits.

Mean.

Calculated.

210

210

IG

68°46'— 69" 0'

68'^53'30"

—

210

Oil

18

48 21 — 48 40

48 30 20

—

Oil

on

8

73 4 — 73 22

73 9 20

73° 5' 0"

101

100

5

65 1—65 8

65 4 20

65 10 0

101

210

10

76 0 — 76 20

76 10 20

76 15 30

100

210

12

55 20 — 55 39

55 31 20

55 33 20

The forms lying in the zone [010] are the largest, but do not give
good reflections on the goniometer. There is a good cleavage parallel
to 6{010j. The following values were obtained :

x: y : z = 7-824 : 2-683 : 3-621.
X : ij/ : a. =10-840 : 3717 : 5-015.

rr=76. r=202-l. fZ= 1-506. ^ = 2-659.

It will be seen that both the equivalence parameters and the
molecular distance ratios correspond closely with those of dimethyl-
amine styphnate.

Afonoethylamine Styphnate, NH2Et,CeH(OH)2(N02)3.

This salt was prepared in the same way as the preceding substance?,
and, after crystallisation from hot alcohol, forms a yellow powder
melting at 138°:

0-1890 gave 30-6 cc. ^^ (moist) at 16° and 773 mm. N= 19-17.
CgHj(jOgN^ requires N = 19-31 per cent.

Poorly-developed, anorthic crystals are deposited from solutions in
water and alcohol. The density of the substance was determined
and the following values found :

/r=70. r=180-0. (2 = 1-61-2. i2 = 2-573.

Triethylamine Styphnate, NEt3,CgH(OH)2(N02)3.

This salt was prepared and purified in a similar manner to the
preceding ones, and was found to melt at 170° :

0-1782 gave 26-0 cc. N2 (moist) at 18° and 748 mm. N= 16-58.

^12^18^8-^4 requires N= 16-18 per cent.
Large, but not measurable, crystals are obtained from acetone
solutions :

^r=94. r=238-3. (2 = 1-452. i2 = 2-535.

Teiraethylammonium Styphnate, CgH(OH)(N02)30*NEt4.

This substance was recrystallised from acetone, and explodes on
heating at about 210°. It was obtained only in the form of yellow
needles, and therefore no density determination was made :

1288

JERUSALEM : THE MORPHOTROPIC RELATIONSHIPS

0-1823 gave 23-0 c.c. N., (moist) at 13° and 776 mm. N = 15-21.
Cj^HooO^N^ requires N= 15-00 per cent.

It is convenient to summarise the results of the measurements
given in the present paper in the following tables ; the numerical
data relating to the axial ratios, molecular distance ratios, equi-
valence parameters, molecular volumes, etc., are thus stated.

Table of Axial Ratios and Equivalence Parameters.

Mxiltiples
Substance. a : h : c. selected. JV. x : y : z. $.

Substances with Hexagonal Marshalling (H).

Ammonium

picrate 1-8914 : 1

Diniethylaniine

pioate 1-9222 : 1

Mouoethylamine

picrate 2-2768 : 1

Triethvlamine

picrate 2 9752 : 1

Tetraethyl-

ammoniuni

picrate 2-9909 : 1

Aniline picrate 3-7120 : 1
Naphthalene

picrate 2 3582 : 1

CeHalNOo)^,

CipHs 2-3170 : 1
Styphnic acid 1-7321 : 1
Mononicthylamine

styphnate.. 0-5232 : 1
Dim ethyl amine

styi)hnate.. 2 9503 : 1
Trimethylamine

styphnate.. 2-9160 : 1

1-3871

—

0-90049

2c

1-5350

—

1-5751

—

1-6075

2-1048

a/2

41846

c/2

4-0961

C/-2

1-3890

0-3716

b/i

1-2606

—

1-3494

.

56 5-251 : 2-776 : 3-852 90°

68 5-186 : 2-698 : 4-859 90

68 6-126 : 2-691 : 4-130 92 27'20"

92 8-026 : 2-698 : 4-249 90

104 8-337:2-788:4-481 92 55 20

84 5-163:2-782:5-855 92 47 50

98 6-401 : 2-715 : 5 679 96 48

96 6-327 : 2731 : 5593 96 36

52 4-825 : 2-786 : 3-869 Hexagonal

64 5-785 : 2-764 : 4-109 76 55 50 '

70 7-849 : 2-660 : 3-354 9126 20

76 7-824 : 2-683 : 3621 90

Substances with Psewlo-euhic Structures (C).

Picric aci.l ... 1-0305 : 1 : 1-0434 — 50 3-706 : 3-596 : 3-752 90°
Monomethylamine

picrate 2-3361:1:1-1529 «/2 62 4-186:3-584:4-132 90

Table of Densities, Topical Parameters, and Quantities R.

Substance. x = 'r' = '^^ ^^- ^- ^- Crystal system.

Substances with Hexagonal Marshalling (H).

Ammonium picrate... 7-174:3-794:5-262 r7l9 143-2 2 557 Orthorliombic
Dimethylamiiie

picrate 7-152:3-721:6-702 1-538 178-4 2-622

Monoethylamine

picrate 8-324:3-656:5-611 1-608 170-6 2-509 Monosymmetric

Triethylamine picrate 11-030 : 3-708 : 5-840 1-383 238-8 2-596 Orthorhombic
Tetraethylamnionium

picrate 11-277:3-769:6-063 1-393 257-3 2-474 Monosymmetric

Aniline picrate 6-973:3-757:7-909 1-558 207-0 2-464

Naphthalene picrate . 8-549:3-625:7-586 1-530 233-5 2-382

BETWEEN THE DERIVATIVES OF I'lCRlC ACID. 1289

I'ahle of Densities, Topical Parameters, and Quantities R (continued).

Substance. x : "^ : <"• '^- ^- -^'''- Crystal system.

Substances loith Hexagonal Marshalling (H).

Stypluiic acid G-615 : 3'S]9 : 5-305 1-829 134-1 2-577 Hexagonal

Monoincthylaiuiiic

slyi.lmate r-OOd : 3-777 : 5-611 1-C92 163-2 2-551 Monosymmctiic

Dimethylamiuc

. styi)linate 10-836 : 3-673 : 4-632 1-575 184-3 2633 „

Triinctliylamiuo

styplmate 10-840:3-717:5-015 1-506 202-1 2-C59 OrtliorhoniLic

Substances with Pseudo-cubic Structures (C).

Picric acid 5-094 : 4-941 : 5-153 1-767 129-7 2-594 Orthoihombic

Monomethylaiiiiuc
pici-atc 5-672:4-857:5-599 1-687 154-2 2-488 ,,

Monoctliylamiuc sty))lniato .
Triethylanuuc ,,

Piperidiue picrate *

Benzylamme piciatc

9«-'r()luidine ,,

o-Toluidine ,,

Pyridine ,, +

d.

V.

IV.

R.

1-612

180-0

70

2-573

1-452

238-3

94

2-535

1-538

204-3

84

2-433

1-536

218-9

90

2-433

1-491

225-6

90

2-506

1-539

218-5

90

2-428

1-537

200-5

78

2-571

* Rosenheim and Sohidrowitz (Trans., 1898, 73, 143).

t Crystals from ethyl acetate washed with alcohol (Ladeuburg, Annalen, 1888,
247. 5).

Two remarkable relationships are immediately obvious from an
inspection of these tables. The first is that, as already remarked, the
z value for the benzene assemblage of hexagonal derivation, namely,
z = 2-780, recurs with very close numerical approximation in the
y value of each picric and styphnic acid derivative the crystalline form
of which indicates a similar hexagonal derivation of the crystalline
structure. The second is, that this approximately constant y value in
each case occurs in a direction perpendicular to a plane of symmetry
of the crystalline structure.

In addition to these two striking regularities in which the equiva-
lence parameter y is concerned, it is also to be remarked that the other
equivalence parameters, x and z, in most cases change in a regular
manner during any given substitution of one group or radicle by
another ; it is frequently observable that such a substitution brings
about an alteration in dimension of only one of these tAvo parameters,
X and z, whilst leaving the other almost unchanged. The investigation
of these changes in a; and z would thus be expected to lead to the
discovery of further i-egularities and to the detection of the laws
governing their alterations; for the present, however, it is convenient

VOL. XCV. 4 P

1290 JERUSALEM : THE MORPHOTROPIC RELATIONSHIPS

to consider only the dimension, y, to which such a definite physical
meaning has been attached.

The fact that the examination of so large a number of benzene deriva-
tives as are crystallographically described above indicates that their
crystal structures can be regarded as of hexagonal derivation, and that
their y values approximate so closely to the z value for benzene itself,
constitutes very strong confirmatory evidence in favour of the con-
clusions previously drawn by Barlow and Pope as to the existence of the
continuous columns of carbon spheres, referred to in the early part of
this paper, as components of the crystal structures of the benzene
derivatives.

The anticipation that, in accordance with the Barlow-Pope interpre-
tation of valency as a volume property, the sums of the valencies
should be roughly proportional to the molecular volumes in the case
of a series of related crystalline substances, is abundantly fulfilled in
the approximate constancy of the ratio, F/TF" — R, for the whole of the
members of the series now discussed. The values of the ratio R for
these substances are stated in the various tables given above ; the
mean value of R is 2'560, and the individual values of the ratio are
distributed about the mean within the limits expressed by

R = 2-560 ± 4 per cent.

It thus becomes possible to calculate the molecular volume, F, of a
member of the present series within about 4 per cent, as

F= 2-560 W.

Similarly, the density, c?, of a member of the series can be calculated
within the same limits of accuracy as

d - J//2-560 IF,

M being the molecular weight of the substance.

As qualitative results from the arguments and conclusions just put
forward, it follows :

(1) That the density of a member of the series must diminish as
the number of alkyl groups contained in the molecule increases.

This is true throughout the series with the single exception of
tetraethylammonium picrate, which has a higher density than triethyl-
amine picrate. It would be supposed, and this is in accordance with
the conclusions of Le Bas concerning the molecular volumes of liquid
substances under equally reduced conditions, that this apparent
exception is connected with the extraordinarily high melting point,
254°, of tetraethylammonium picrate.

(2) The density of a styphnic acid derivative should in each case be
greater than that of the corresponding pici'ic acid compound. This is
true in all the cases now examined.

BETWEEN THE DERIVATIVES OF riCRIC ACID. 1291

From the observation tliat the ratio li = V/Win so approximately
constaut throughout the series of picric and styphnic acid derivatives,
it is evident that the study of the 0(]uivalence parameters and of the
molecular distance ratios leads, in the present case, to the same con-
clusions. It is therefore unnecessary to discuss further the relation-
ships between the molecular distance ratios of the substances now
described.

In most cases the equivalence parameters are calculated directly
from the axial ratios, using the latter in the form in which they were
experimentally determined ; in some few instances, as indicated in the
text and in the table on p. 1228, one of the axial dimensions has been
multiplied or divided by two before proceeding to the calculation of
the equivalence parameters or the molecular distance ratios.

As this process of multiplication or division introduces an arbitrary
element into the subsequent calculation, it might conceivably be
argued that the necessity for this process weakens the conclusions as
to the constancy of the equivalence parameter y, etc. Although the
infrequency with which the necessity for the multiplication or division
arises, the simplicit}'' of the factors used, and the close agreements of
the results obtained, show that such an argument is fallacious, a
method was nevertheless devised to show mathematically that the
approximate constancy of the parameter y constitutes a law of nature
as opposed to the view that this constancy is devoid of physical
meaning, and results merely from the arbitrary multiplication and
division of the axial ratios. By taking into account all the different
ways by which a value near y might be found by the alteration of the
axial ratios used in the foregoing pages, that is, by a multiplication
by 2 or |- of only one of the unit values in the axial directions, it is
possible to state the mean difference of all the values thus found, and
to compare this mean difference with the actually observed differences
between they values in the table of equivalence parameters on p. 1228.
In this way it is possible, for example, to calculate the probability that
a table of axial ratios, chosen at mere random, will show y values
agreeing with one another within the same limits as the y values of
the table. This probability is found to be much smaller than a
magnitude of the oi'der 1/4^^. Details of this method will be published
elsewhere.

Univeusity Chemical Ladoratoiiy,
Cambridge.

4 P 2

1292 HEWITT AND THOMAS : THE COLOUR AND

CXLIV. — TJie Colour and Constitution oj
Azo-comj^ounds. Part III.

By John Theodore Hewitt and William Thomas.

ftATHEU more than a year ago one of the authors of the present
communication, jointly with J. J. Fox, published an account of some
mixed single azo-compounds, the benzene nucleus on the one side of
the azo-group being substituted in the para-position by a dimethyl-
amino- or trimethylammoniuin group, whilst the other nucleus, in this
case naphthalene, contained hydx-oxyl in the a-position, the azo-group
having entered the naphthalene in position 4 (Trans., 1908, 93, 333).
The results showed that if to substances of this type dilute acid be
added, salt formation for which tho diaiethylamino-group is responsible
(see formula I) takes place, with addition of one molecule of acid :

I. (ch3)2N-CcH^'N:n-CioHo-oh.

II. HCl(CH3)2N-C,;H4-N:N-OioHy'OH.
III. Cl(CH3)2N:C6H4:N-NH-CioHg-OH. .

lY. ClH(GH3).N-C,.H4-NH-N:CjoHe:0<J?p

but w^iether the resulting salt is non-quinonoid (II) or quinonoid
(III) was not investigated at the time. An excess of a strong acid
involved the formation of a di-acid salt, and the explanation of this
fact, as well as the great deepening in colour, was referred to oxonium
salt formation (see formula IV above and table p. 338, loc. cit.),
several di-acid salts being isolated and analysed.

Shortly after the publication of this work, it struck one of the
authors as a virtual certainty that if the relationship of benzeneazo-
phenol to its hydrochloride was to be represented by the formulaj

CgH\,-N:N-CoH4-OH and C,H^-NH-N:CeH4:0<^p

then, similarly, aminoazobenzene and its hydrochloride would possess
the corresponding constitutions :

CgH^-NIN-C^H.-NIia and CgH^-NH-NiCoH^INH^HCl,
so giving a I'easouable explanation for the marked colour change
produced on the conversion of the base into a salt. The application
of this view to the case of the indicator methyl-orange (Hewitt,
Analyst, 1908, 33, 85) leads one to the result that the sodium salt
and the "free acid " or internal salt have the constitutions,
NaS03-C,H,-N:N-C6H,-N(CH3), ar.'l S02-C6H^-NH-N:C6H4:N(0H3)2

0 '

CONSTITUTION OF AZO-COMPOUNDS. 1293

respectively ; the saino formuliB were published shortly .afterwards by
Hantzsch and Hilscher {Ber., 1908, 41,1171). In some discussion as to
pi'iority which followed (Hewitt, Ber., 1908, 41, 1986 ; Hantzsch, ibid.,
2435), Fox published the interesting experimental fact that methyl-
orange is readily decomposed by warm dilute nitric acid with produc-
tion of diazoljsnzenesulphonic acid and 2 : 4-dinitromo?iomethylanilino,
one of the methyl groups being eliminated in the reaction {Ber.,
1908, 41, 1989). This result is certainly in better agreement with a
quinonoid structvire for the "free acid " than a structure involving an
unaltered azo-group.

Whilst the work published last year will probably convince most
persons intimately acquainted witli azo-compounds of the quinonoid
structure of the salts of the amino-derivatives, it appeared worth
while to examine a case in which both aromatic nuclei were benzenoid,
both on account of greater simplicity and to avoid the possible objec-
tion that the simplest case had not been examined and might possibly
give different results to those obtained with naphthalene derivatives.

The expectation was that aminobenzeneazophenol, which has already
been examined at some length by Meldola (Trans., 1885, 47, 659),
whilst giving yellow solutions in neutral solvents, would furnish
solutions similar to that of acidiBed methyl-orange in presence of a
medium amount of mineral acid, but that in concentrated mineral
acids the colour would be comparable with that given by benzeneazo-
phenol, the structures of the substance and its mono- and di-acid
salts being i^epresented by the constitutions :

NHg-CyH^-NIN-C^H^-OH yellow.

C1NE[2:Cj;H^:N-NH-C,,H,-0H crimson.
ClHNHa'CgH^-NH-NlbeH^IO orange.

This expectation was fully confirmed by experiment, .and the
probability of the constitutions assigned to the respective substances
received ample verification by the examination of the alkyl derivatives.
The same colour changes were observed when the hjdrogen atoms of
the amino-group alone or of that and the hydroxyl group were replaced
by methyl ; obviously from the formulae no radical difference is to be
expected. But when hydroxy- or ^j-methoxy-benzeneazodimethylaniline
was converted into a methiodide, whilst the colour of the salt in
neutral solution was yellow, addition of hydrochloric acid produced no
crimson shade, although if the acid were sufiiciently concentrated the
orange colour, associated in this case with oxonium salt formation,
made itself manifest, A consideration of mono- and di-acid salts in
this case shows the impossibility of the development of the quinonoid
configuration with respect to that benzene nucleus to which the amino-

1294 HEWITT AND THOMAS: THE COLOUR AND

group is attaclied, whilst no inhibition of possible quinonoid structure
has occurred with respect to the other nucleus :

ci(ch3)3N-C6H,-n:n-C6H4-o-ch3.

Cl(CH3)3lSr-C6H4-NH-N:C6H4:0<^J^3.

Two points observed with regard to the photographs are well worth
mention. The general type of quinonoid salt absorption is much the
same whether the quinonoid grouping is of the type

>o:c6H4:n- or >nh:c6H4:n-,

but when the grouping is conditioned by double linking between
carbon and nitrogen the oscillation frequency is less than when it is
between carbon and oxygen. Ordinary chemical experience leads one
to the conclusion that the linking CIN is weaker than CO, and this
would necessarily condition a slower rate of vibration.

■p-Aceti/laminobenzeneazophenol.

In the preparation of ^>aminobenzeneazophenol we decided to use
75-aminoacetanilide as starting point. This was dissolved in a little
more than two molecular proportions of dilute hydrochloric acid
(2 vols, of fuuiiug acid to 5 vols, of water), diazotised with the calcu-
lated amount of sodium nitrite, and coupled with phenol in the
presence of sodium carbonate. After acidification, collection, and
crystallisation from dilute alcohol (equal volumes alcohol and water)
the compound was obtained in beautiful reddish-brown plates melting
at 198° (uncorr.) :

0-2183 gave 0-5272 COg and Q-lOll HgO. 0 = 65-9 ; H = 5-L
^14^13^2-^3 requires 0 = 65*9; H = 5-l per cent.

■p-Aminobenzeneazophenol.

The acetyl derivative was hydrolysed by boiling for two to three
hours with 20 parts of 20 per cent, hydrochloric acid. The magenta-
coloured solution on neutralisation with sodium carbonate gave a pre-
cipitate of the amino-compound amounting to about 70 per cent, of the
weight of the material taken. In the crude condition this melted at
177° (uncorr.) ; after crystallisation melting points of about 185° were
observed. Meldola (loc. cit.) gives 181° ; no weight can be laid on a
difference of a few degrees in these cases, as most of the substances
examined decompose at the melting point, and the temperature
observed necessarily depends on the rate of heating :

0-1038 gave 17-2 c.c. Ng at 18° and 772 mm. N = 19-5.
OigHjjONg'^requires N = 19-7 per cent.

CONSTITUTION OF AZO-COMPOUNDS.

1295

The substance gives yellow solutions in neutral solvents ; addition of
dilute hydrochloric acid produces a magenta shade, but if concentrated
hydrochloric acid be employed in excess., the solution becomes orange,
owing to the production of di-acid salts. As Meldola has already
isolated a platinichloride in which the azo -compound behaves as a
mono-acid base, it was unnecessary for us to prepare any salts of this
type, but on passing dry hydrogen chloride through a benzene solution
of the base, a dark red precipitate was obtained, which was rapidly

Fig. 1.

Oscillation frequencies.

16 18 2000 22 24 26 28 3000 32 34 36 38 4000 42 44

26

24

22

20

18

16

14
s
I 12

I 10

"1^

i

^

—

—

—

\ /

r.

^

■^^

\

V

/ :

y

4

V

\,

\
\

/

/

/

\

--. ,

t

\

/

^\

v,1

1 ^

\

7

t

f^

\

V

_..•

..''

"^^Z

1 ,

2.50

100 ;c

25

10

Aminohenzeneazophcnol. N/10, 000.

In alcohol.

In dilute hydrochloric acid,

— — — In concentrated hydrochloric acid.

ollected, washed with benzene and light petroleum, and dried over
ulphuric acid. This proved to be the di-acid salt :

01651 gave 0-3047 CO2 and 0-0732 HgO. C = 50-3 ; H = 4-9.

0-1545 „ 0-1501 AgCl. HOI = 24-7.
C\2Hj30N3,2HCl requires C = 50-3 ; H = 4-5 ; HCl = 25-5 per cent.

Fig. 1 gives the absorption spectra observed in the case of ^j-amino-
lenzeneazophenol without and with hydrochloric acid.*

'p-Dimethylammobenzeneazophenol.

The process adopted by Fox and Hewitt (loc. cit.), which consisted
n diazotising ^-phenylenedimethyldiamine and coupling with alkaline

* The curve for the dihydrochloride is not complete, as we suspected some hydro-
^sis, even with a large excess of hydrochloric acid present.

120(i HEWITT AND THOMAS: THE COLOUR AND

a-naphthol, proveil unsuitable in this case. The diazonium salt is
extremely unstable, and phenol does not couple so rapidly as
a-naphthol, so that very little except tarry decomposition products
was obtained.

5 "45 Grams of ;>aminophenol dissolved in 12 c.c. of concentrated
hydrochloric acid and 25 c.c. of water were diazotised with 3"5 grams
of sodium nitrite dissolved in 10 c.c. of water, and the solution added
to 6"05 grams of dimethylaniline dissolved in 50 c.c. of glacial acetic
acid mixed with ice and water in which sodium acetate had been
dissolved in sufficient quantity. After keeping overnight, excess of
water was added, and the precipitated azo-compound collected.
The best yield obtained was 6 "5 grams of crude product. On crystal-
lisation from alcohol, bright red leaflets were obtained, melting and
decomposing at 203 — 204° :

0-1568 gave 0-3991 CO2 and 0-0875 HgO. 0 = 69-4; H = 6-2.

0-1248 „ 0-3189 OO2 „ 0-0714 H.Jo. 0 = 69-7 ; H = 6-4.
Cj^HjjONg requires 0 = 69-7 ; H = 6-2 per cent.

The solution in dilute hydi'ochloric acid is magenta in colour, and
yields a dark-coloured monohydrochloride on evaporation :

01411 gave 0-0724 AgOl. 1101 = 13-3.

Oj^HjjONg.HOl requires HCl = 13-2 per cent.

ip-Bimethylaminobenzeneazophenyl Acetate.

Acetylation of the phenol was effected by fchi'ee and a-half hours'
boiling with its own weight of fused sodium acetate and four times its
weight of acetic anhydride. Excess of acetic anhydride was destroyed
by pouring into alcohol, and the substance was precipitated by the
addition of water. When crystallised from alcohol, the substance
was obtained in brown plates melting at 137° (uncorr.) :

0-1376 gave 0-3402 CO2 and 0-0747 HgO. 0 = 67-4 ; 11 = 6-0.
C'lgH^yOgNg requires 0 = 67*8 ; H = 6-0 per cent.

T^-Diniethylaminohenzeneazophenol Methiodide.

The dimethylamino-compound was heated for four hours at 100°
with its own weight of dimethyl sulphate. The product was dissolved
in hot water, filtered, and treated with an excess of potassium iodide,
the iodide of the base separating on cooling. This was collected and
obtained in black scales by crystallisation from alcohol :

0-1427 gave 13-5 c.c. Ng at 19° and 769 mm. N= 11-2.
OjjjHjjjONgI requires N= 11-0 per cent.

As previously mentioned, this .salt dissolves in water with a yellow
colour, .strongly contrasting with the isomeric salt of ^^-methoxy-
benzeneazodimethylaniline ; this yellow colour is not affected by

CONSTITUTION OP AZO-COMPOUNHS.

1207

dilute acids, but gives place to .an orange shade on formation of
oxonium di-acid salts.

The absorption spectra of dimethylarainobenzeneazophenol are given
in Fig. 2.

^-Methoxyhenzeneazodimethylaniline.

6-15 Grams of ;>anisidine dissolved in 16 c.c. of concentrated hydro-
chloric acid and 30 c.c. of water were diazotised by the addition of a
solution of 3-5 grams of sodium nitrite, ice being added to the solu-
tion. The diazonium salt was then added to (5-05 grams of dimetliyl-
aniline emulsified witli 30 c.c. of glacial acetic acid, 8 grams of

Fig. 2.
Osdllation frcqiieneics.
IG IS 2000 22 24 26 28 3000 32 34 36 38 4000 42 44

"fe^

26

16K-
14

12

10^

—

—

1

;

•1
•1

\

^

"X

'; \

\

\

\

A

_

/^

«

1

/

/

\

\ '

N

I

/
/

;

/

~^

V

X

V
V

i

\

/
/

/

\

K

/

/

\ ■

vj

^

250

100

25

10

Dimethylaminobenzeneazophenol. N/10, 000.

Ill alcohol.

In dilute hydrocliloric acid.

In concentrated hydrochloric acid.

crystallised sodium acetate, and much ice. After seventeen hours
the product was collected, wiished, and crystallised. Using pyridine
as solvent, brilliant orange prisms melting at 161° (uncorr.) are
obtained, but from alcohol bro-.vn (almost bronze-coloured) plates and
needles are deposited. The appearance of the two preparations is
quite distinct, but no claim is made for the existence of two
modifications, as both specimens alone and mixed show the same
melting point :

0-1155 gave 16-1 c.c. Ng at 14° and 772 mm. N=16-6.
CjjHjyONg requires N = 16"5 per cent.

1208 THE COLOUR AND CONSTITUTION OF AZO-COMPOUNDS.

The solutions in neutral solvents are yellow, in dilute acids magenta
(almost violet), and orange in concentrated acids.

T^-Methoxyhenzeneazodimethylaniline Methiodide.

This was prepared in a similar manner to the corresponding phenolic
derivative :

0-1524 gave 13-8 c.c. N, at 25° and 770 mm. N- 10-4.
Cj^^HjoONgl requii-es N = 10"G per cent.

Fig. 3.

Oscillation frequencies.
IC 18 2000 22 24 26 28 3000 32 34 36 38 4000 42 44

26

241 1 1 1 ! 1 \ ] 1 1 1 1 1 1 1250

22

20 1 1 1 1 1 1 1 \ 1 1 1 1 1 1 1 1 00

18
16

14 1 11 l\ I. '4./ 1 1/ \- A A 1 ^-iJ 1 ^25

12

lol V^ HV/i yr •'-.[ — -I- 1 1 1 1 l-Vl 10

8

6

4

2

0

i^'Methoxybenzeneazodimethylaniline. N/1 0, 000

In alcolwl.

In dilute hydrochloric acid.

— In concent7-alcd hydrochloric acid.

The aqueous solution is yellow, remains unaffected by dilute acids,
but gives an orange shade with concentrated hydrochloric acid.

In conclusion, we wish to tender our thanks to the Government

Grant Committee of the Royal Society for a grant by which part of

the expenses of this investigation have been defrayed, and to Miss

C. H. Watts for assistance with the photographic portion of the work.

East London Collkge.

"^

,-

-^

\''.

/
/

. 1

/^

\

y

\

s\

V.
1 •■.

1 •-,

]

'

••■■'

^*s

^

S^

— ]

^

/

X

1 jr'

—

"\

\

— t—
\
\

1

•

1
1
1

—

\

1

\

i 1

\ 1

■•••

'^J

CLARKE: WOLCOTT GIBBS MEMORIAL LECTURE. 1299

WOLCOTT GIBBS MEMORIAL LECTURE.

Delivered on June 3rt), 1909.

By Frank Wigglesworth Clarke.

It is easy to write biography when one is satisfied with a mere
chronicle of events. But to clothe the skeleton of fact with flesh
and blood, so that the man shall, as it were, live again, is difficult,
and yet, figuratively speaking, that seems to be the sort of task
which you have set before me. What manner of man was Wolcott
Gibbs ? What influences helped to mould his character ? What
did he do, and under what conditions was his work accomplished ?
These are the questions which I must try to answer.

Oliver Wolcott Gibbs (he dropped the Oliver early in his career)
was born in the city of New York, on February 21, 1822. His
father. Colonel George Gibbs, was a man of some wealth, who
owned a large country place at Sunswick, on Long Island, not
far from the then small city. He was an enthusiastic mineralogist,
and gathered a collection which, ultimately sold to Yale College,
became the nucleus of the great cabinet since made famous by the
labours of the two Danas, Brush, and Penfield. It was perhaps
the control of the Gibbs collection which first led J. D. Dana to
write his classical System of Mineralogy. Colonel Gibbs, after
whom the mineral gibbsite was named, was himself the author of
several memoirs upon mineralogical subjects, and his eldest son,
also named George, achieved some reputation as a geologist and
as a student of ethnology. Wolcott Gibbs was born into an
atmosphere of scientific interests, and his early associations must
have influenced his choice of a career. A taste for science ran
in the family.

Laura Gibbs, the mother of Wolcott, came of distinguished
ancestry. Her father, Oliver Wolcott, rose through various
positions to that of Secretary of the United States Treasury, a
post which he held during the latter part of Washington's
administration and well into the administration following. He
then became a Justice of the United States Circuit Court, and
during the last ten years of his life he was Governor of the State
of Connecticut. His father, another Oliver, was a magistrate, a
major-general of militia, a member of Congress, and a signer of
the American Declaration of Independence. He, too, was a
Governor of Connecticut, and so also was his father, Roger
Wolcott, the first noteworthy member of the line. In short, the
ancestors of Wolcott Gibbs were people of far more than average

1300 CLARKE: WOLCOTT GIBBS MEMORIAL LECTURE.

ability, who had the confidence and esteem of their fellow citizens,
and were therefore entrusted with positions of high rank and
responsibility. Even though there was no commanding genius
among them, no man of world-wide fame, they at least left to their
descendants a legacy of lofty examples, well worthy of emulation.
We may differ in our opinions as to the significance of heredity;
but we can recognise the fact that Gibbs received from his forbears
a sound mind in a sound body, together with traditions of well-doing
that could not be disregarded. A good ancestry is a good beginning
for any man.

In his early environment Gibbs was also fortunate. Although
he was only eleven years old when he lost his father, his mother
survived for many years, and gave him the best of opportunities
for healthy development. She was a woman of strong character
and unusual ability, and her home became a centre in which the
best intellectual society of New York was to be fovmd. Her
character, forceful, positive, patriotic, and public-spirited, was
reflected in that of her son.

The early childhood of Wolcott Gibbs was largely spent at his
father's estate of Sunswick, where, as he tells us in a brief auto-
biographical note, " he was often occupied with making volcanoes
with such materials as he could obtain, and in searching the stone
walls . . . for minerals, and the gardens and fields for flowers."
At the age of seven he was sent to a private school in Boston,
where he was under the care of a maiden aunt, whose sister had
married the famous Unitarian divine, William Ellery Channing.
The winters were passed in Boston, and the summers with the
Channings at their country place near Newport, Rhode Island.
Here again he was surrounded by choice influences, and saw many
distinguished jDOople. The reputation of Dr. Channing attracted
many visitors, including more than a few from abroad, and the
boy must have come to some extent in contact with them. Being
but a child, he may not have understood or appreciated his
opportunities, but his imagination could not have been entirely
unaffected. His early associations foreshadowed his later career.

When he was twelve years old, Gibbs returned to New York,
and began his preparation for college. In 1837 he entered
Columbia College as a freshman, and graduated in 1841. It was
in his junior year that he published his first scientific paper, a
description of a new form of galvanic battery, in which carbon
was used, probably for the first time, as the inactive plate. This
achievement, unimportant as it may seem now, was really remark-
able in two ways; first, on account of the youth of the author,
and, secondly, because of the conditions under which the work was

CLARKE: W()LC(rrT GllillS MI;M()K1A1. l.KCTUKE. loOl

done. In those days tbe American colleges, like the public
schools of England, were intensely classical in their aims, and
science received the minimum of attention. Latin, Greek, and
mathematics ruled the curriculum, with only a smattering of other
subjects. Even in the classics literature was subordinate to
grammar, and as for the modern languages they were almost, if
not quite, ignored. What science was cultivated was taught by
lectures and text-book recitations, for the era of laboratory instruc-
tion had not begun. That a pupil of eighteen should make an
original investigation under such conditions was surprising, but
it showed the irresistible tendencies at work in his mind. The
early impulses, received from his father, could not be overcome.

After receiving his bachelor's degree, young Gibbs went to
Philadelphia, where he served as assistant in the laboratory of
Robert Hare, the well-known inventor of the compound blow-pipe,
who was then Professor of Chemistry in the Medical School of the
University of Pennsylvania. Gibbs's purpose was to fit himself
for holding a similar professorship, and so, after several months
of experience with Hare, he entered the College of Physicians and
Surgeons in New York, and in 1845 became a full-fledged Doctor
of Medicine. He never practised, and probably never intended
to do so, for the study of chemistry was the main purpose of his
life, and his medical studies were only a means to an end.
Indeed, they stood him in good stead when, many years later, he
undertook to study the physiological effects of isomeric organic
substances on animals.

Up to this point the training of the future chemist had been
only preliminary, a laying of foundations, so to speak. In his
time advanced scientific education was not easily obtained in
America, and ambitious students who were able to do so sought
their higher opportunities in Germany. Accordingly, Doctor
Gibbs, as we must now call him, went abroad, and began by
spending several months with Rammelsberg in Berlin. After this
he studied for a year under Heinrich Rose, which was followed
by a semester with Liebig at Giessen. He next went to Paris,
where he attended lectures by Laurent, Dumas, and Regnault,
and in 1848 he returned home, ready to begin the real labours of
his life. Among his teachers the one Avho most impressed him
was Rose, whom Gibbs greatly admired, and w-ho doubtless gave
his pupil his strong bias towards analytical and inorganic chemistry.
From his other teachers, however, Gibbs acquired a breadth of
view and an insight into difi'erent fields of research, which made
him all the stronger as an investigator. He was a chemist in the
largest sense of the term, and not a mere sub-specialist.

1302 CLARKE: WOLCOTT GIBBS MEMORIAL LECTURE.

After returning to America, Gibbs first delivered a short course
of lectures at a small college in Delaware. Then, in 1849, his
native city claimed his services, and he was appointed professor
of chemistry in the newly established Free Academy, now the
College of the City of New York. He remained in this position
for fourteen years, chiefly occupied in teaching elementary students,
and at first doing, apparently, little else. He was not idle by
any means, but he was finding himself, and his time was not
wasted. In was in 1857 that his first really notable research was
given to the world, namely, the joint memoir of Gibbs and Genth
on the ammonio-cobalt bases. Of this I shall speak more at length
later. In 1851 he became an associate editor of the American
Journal of Science, and began the preparation of a series of
abstracts which brought the results of foreign investigations to
the attention of American readers. These abstracts amounted in
all to about 500 pages, and, despite their brevity, were con-
spicuously clear and comprehensive. In 1861 the first of his papers
on the platinum metals appeared, and his reputation was at last
firmly established.

Notwithstanding his recognised ability. Dr. Gibbs, during this
period, suffered one serious disappointment. The chair of
chemistry in his alma mater, Columbia College, became vacant,
and Gibbs, backed by the recommendations of nearly all the
leading men of science in America, was a candidate for the position.
He was, however, a Unitarian, and Columbia was then an institu-
tion under sectarian control. Purely on religious grounds, his
candidacy was rejected, and a man of far smaller attainments
received the appointment. This was unfortunate for Columbia,
but not altogether so for Gibbs. In 1863 he was called to a
more desirable post, the Rumford Professorship in Harvard
University. Nominally, this was a professorship of the " Applica-
tion of Science to the Useful Arts," but its incumbent, in addition
to lecturing on heat and light, was expected to take charge of
the chemical laboratory in the Lawrence Scientific School, and
this gave Gibbs a great opportunity for usefulness. Furthermore,
the position was a delightful one on its social side, and he was
thrown into close association with many congenial spirits. There
were Louis Agassiz the zoologist, Asa Gray the botanist, Jeffries
Wyman in comparative anatomy, Benjamin Pierce in mathematics,
and J. P. Cooke in chemistry. Literature was represented by
Longfellow, Lowell, Holmes, and other less famous writers;
altogether an aggregation of distinguished men which could not
be matched elsewhere in America, or equalled at few places in the
world. Gibbs was among his peers, and in a place where his worth
could be fully appreciated.

CLARKE: WOLCOIT GIBBS MEMORIAL LECTURE, 1303

Dr. Gibbs remained in charge of the Scientific School laboratory
for eight years, and during that time his researches were, for the
great part, although not exclusively, devoted to analytical methods.
The school was technically a department of Harvard University,
and yet its work was carried on quite independently. The students
were usually men of definite purposes, who knew what they wanted
and went where it could be best obtained. They went to Agassiz
for zoology, to Gray for botany, and to Gibbs for chemistry, because
those men were the leaders in their respective subjects, and they
worked, not in classes, but as individuals. The students in chemistry
had little or nothing to do with the students in other branches,
for the school was distinctly professional in its aims. Teachers
from other institutions, seeking to enlarge their knowledge, were
often among them. Gibbs was now training men who intended
to become chemists, and some among them were qualified to assist
in his investigations. Moreover, he was not overloaded by numbers,
for he rarely had more than twenty students in attendance at any
one time. There was one assistant, to relieve him of routine work ;
his lectures on light and heat cost him little effort, and he was
therefore able to devote his energies to research more advantageously
than ever before.

It was my good fortune to have been a student under Gibbs
during the greater part of four years, from 1865 until 1869. I may
therefore be permitted to speak of his teaching from my own
experience, believing that in such matters the personal note is not
without value. There was nothing unusual about the course of
instruction so far as ordinary details went, for that necessarily
followed certain well-established lines. Most of the students had
already gained some elementary knowledge of chemistry ; their work
began with the usual practice in analytical methods and chemical
manipulations, and as the men showed capacity they were admitted
to the confidence of their master and aided him in his investiga-
tions. This procedure may seem commonplace enough to-day, but
in the years of which I speak it was new to American institutions,
and was looked upon doubtfully by some of the old-fashioned
pedagogues. The students who chose to do so attended the excellent
chemical lectures of Cooke in Harvard College, but that work was
wholly optional. The only formal examination was the final
examination for the bachelor's degree, and therefore there was no
cramming for examinations. Gibbs apparently believed, although
his belief was not stated in set terms, that a good teacher who
kept in touch with his pupils should know perfectly well where
they stood, and no examination could tell him anything more.
In fact, examinations arc often misleading, for the reason that
even a fine scholar of nervous temperament may become confused

1304 CLARKE: WOLCUir giisiis mhmoihal leciuke.

aud liclpless during the ordeal, and fail to answer the simplest
questions. Ou the other hand, a poor student with a fair memory
may cram for an examination, pass triumphantly, and amount to
nothing afterwards. The real examinations under Gibbs were daily
interviews, when he visited each student at his laboratory table
and questioned him about his work. This, together with the
reported analyses, gave the teacher a clear conception of the true
standing of each man. The fewness of the pupils was a distinct
advantage, for all worked together in one room, beginners and
research students often side by side. The result was that they
learned much from one another, and there were many discussions
among them over the burning problems of the day. The men
were taught to stand on their own feet, and to think for them-
selves, laying thereby a foundation for professional success which
was pretty substantial. The course of instruction had no definite
term of years prescribed for it, and graduation came whenever the
indi.idual had done the required amount of work and submitted
an acceptable original thesis. The final examination was usually
oi'al, each man alone with his master, and was conducted in an
easy conversational way which tended to establish the confidence
of the candidate from the very beginning. In my own case I
remember that the questions covered a fairly broad range of
chemical topics, aud at the end of it Dr. Gibbs drew me into a sort
of discussion or argument with him over the then modern doctrine
of valency. I now see that his purpose was not merely to ascertain
what I had read on the subject, but what I really thought about
it, if indeed I was entitled to think at all. Gibbs invariably
ti-eated his students, not as so many vessels into which knowledge
was to be poured, but as reasonable beings, with definite purposes,
to whom his help must be given. That help was never denied to
any man who showed himself at all v,-orthy of it. The research
work in which the advanced students shared, and for which they
received public credit, served to teach them that chemistry was
a living and growing subject, and to train them in the art
of solving unsolved problems. They were taught to do, and
encouraged to think, and if, on going forth into the world, they
sometimes felt themselves qualified to revolutionise all science, their
vanity did no harm and was soon remedied. An enlightened
ignorance is only gained with advancing years, and the enthusiastic
beginner cannot be expected to appreciate it. It is the last polish
that the ripened scholar acquires.

What now is the meaning of this long disquisition upon the
methods of Gibbss laboratory ? What was there at all unusual in
his teaching ? Nothing, perhaps, from a modern point of view,

CLARKE: WOLCOTT GIBBS MEM(31UAL LECTURE. loOo

but much that was new to America in the middle 'sixties. It was
Gibbss peculiar merit that he, more than any other one man,
introduced into the United States the German conception of
research as a means of chemical instruction, a conception which
is now taken as a matter of course without thought of its origin.
Gibbs worked with small resources and no help from outside; he
was a reformer who never preached reform ; his students rarely
suspected that they were doing anything out of the ordinary; but
they had the utmost confidence in their master, and took it for
granted that his methods were sound. There was nothing of the
drill master about Gibbs, no trace of pedantry, no ostentation of
profound learning; but the students never doubted his sincerity
of purpose and interest in their work, nor questioned his ability
as a teacher. As for Gibbs himself, it is doubtful whether he ever
imagined that his teaching was at all remarkable. He did what
was to him the natural and obvious thing to do, simply and without
pretence, and the results justified his policy. The success of his
students is perhaps the best monument to his memory.

In 1871 the chemical instruction at Harvard University was
reorganised, in spite of vigorous protests from Gibbs and many
other leaders in science. The laboratory of the Scientific School
was consolidated with that of the College, and Gibbs had no more
students in chemistry. His work was limited to that of the
Rumford professorship, a change which left him more time for
personal research, but took from the students the inspiration of
his teaching. The change may have been justifiable on grounds
of economy, but it was otherwise a mistake, and it was so recognised
among chemists generally. The economy was only financial; but
an important asset of the University, the ability of a great teacher,
was not turned to the best account. Fortunately for Gibbs, he
had independent means, although he was not a rich man, and he
was able to eqiiip a small laboratory of his own and to employ a
private assistant. In that laboratory he carried out those brilliant
researches on the complex inorganic acids which marked the
culmination of his career. The equipment was most modest, and
in some respects it reminded one of the famous kitchen of Berzelius.
Indeed, Gibbs's favourite piece of ajaparatus was that homely
utensil, a cast-iron cooking stove, which served for several useful
purposes. Precipitates could be dried in the oven, crucibles were
buried in the coals, water was kept hot on top of it. As an
instrument of research it was neither elegant nor orthodox, but
it did the work, and what more could be desired ? Gibbs adapted
himself to circumstances, and cared little for the instrumental
refinements which so many chemists seem to regard as necessary.

VOL. XCV. 4 Q

1306 CLARKE: WOLCOTT GIBBS MEMORIAL LECTURE.

The real essentials ^vere provided; mere conveniences, the luxuries
of research, he could do without.

For sixteen years after the closing of the Scientific School
laboratory, Dr. Gibbs lectured to small classes of students on the
spectroscope and on thermodynamics. In 1887 he retired, as
Professor-Emeritus, and went to live in his house at Newport,
where he had been accustomed to spend his summer vacations.
His private laboratory was moved to Newport also, and there he
continued his investigations until, enfeebled by old age, he was
obliged to rest on his laurels. As a recreation, he cultivated a
flower garden, and was proudest of his roses. In that way his
love of the beautiful found its chief expression. On December 9,
1908, he passed away, at the age of nearly eighty-seven. His wife,
whose maiden name was Josephine Mauran, and whom he had
married in 1853, died several years earlier, leaving no children.

So much for biography. It now remains for us to consider the
contributions of Gibbs to science, and to trace their relations, so
far as may be practicable, to later woi'k. An investigation never
stands alone; each one touches other investigations at several
points; and its worth may be greatest as the progenitor of later
researches. The suggestiveness of a discovery, its influence in
stimulating thought, is fully as important as its immediate outcome.
It is a seed, whose value is finally determined by its fertility.

Gibbss first paper, a '" Description of a New Form of Magneto-
Electric Machine, and an Account of a Carbon Battery of Con-
siderable Energy," published when he was a junior student at
Columbia, has already been mentioned. In 1844 he attempted to
discuss the theory of compound salt radicles, and in 1847, while a
student abroad, he published a number of mineral analyses. In
1850, Gibbs pointed out the interesting fact that compounds which
change colour when heated do so in the direction of the red end
of the spectrum. In 1852 he published the first of his memoirs
upon analytical methods, in which he proposed the separation of
manganese from zinc by means of lead peroxide; and in 1853 he
prepared, and partly described, an arsenical derivative of valeric
acid. In all of this work there was nothing of great importance,
but its varied character is suggestive. It represents the efforts of an
active mind, feeling its way under unfavourable conditions, and
not quite sure of its true capacities. Mineral chemistry, organic
chemistry, analytical chemistry, chemical theory, and physics, in
turn attracted his attention during this formative period of his
career. It was in the great research on the ammonio-cobalt bases
that Gibbs finally found himself, and forced the world to recognise
his ability. His apprenticeship was ended, and his work as a
master had begun.

CLARKE: WOLCOTT GIBBS MEMORIAL LECTURE. 1307

The first of the ammonio-cobalt compounds, the oxalate of
luteocobalt, was prepared by Gmelin in 1822, the very year in
which Gibbs was born. It was supposed, however, to be a salt of
cobaltic acid, and several other chemists, who studied it later,
shared in the same misapprehension. In 1847, Genth, then at
Marburg, discovered other salts of these bases, but it was not
until 1851, after his emigration to America, that he published his
description of them in a rather obscure journal. Genth was the
first to recognise the true character of the new compounds, and
he was followed by Claudet and Fremy, the three chemists working
independently of one another and almost simultaneously. Up to
this point Fremy's work was the most exhaustive, but it left much
to be desired.

Genth had identified the two bases since known as luteocobalt
and roseocobalt. In 1852 Gibbs discovered the salts of xantho-
cobalt, which contained, in addition to the ammonia, a nitro-group.
It was therefore quite natural that the two chemists should join
forces, and in 1856 their celebrated memoir appeared. In this
memoir thirty-five salts of the four bases roseocobalt, purpureo-
cobalt, luteocobalt, and xanthocobalt wore described, with adequate
analyses, and, in eleven cases, crystallographic measurements by
J. D. Dana. The roseo- and purpureo-compounds were for the first
time clearly discriminated, although they were supposed to be
isomeric, a misconception which could hardly have been avoided at
that time. There was also an elaborate theoretical discussion on
the constitution of the bases, but that also was premature. The
fundamental theories of structure were yet to be developed.
Blomstrand, Jorgensen, and Werner, in later years, utilised the data
of Gibbs and Genth, and Werner especially made the ammonio-
cobalt compounds the base of his famous theory of the constitution
of the metal-amines. Gibbs and Genth laid the foundations, on
which later investigators have built an imposing structure.

Gibbs was an experimentalist rather than a theorist, and yet he
neither underrated nor avoided theory. In 1867 he published a
paper on atomicities, or valences as they are now called, in which
he developed the idea, then vaguely held by others, of residual
affinities. He argued in favour of the quadrivalency of oxygen,
and showed that on that supposition a molecule of water must be
bivalent, and any chain of water molecules would be bivalent also.
He then considered ammonia in the same way, with the two bonds
of quinquevalent nitrogen unsatisfied. Ammonia, therefore, was
weakly bivalent, and so, too, would be a chain of ammonia molecules.
This conception he applied to the interpretation of the ammonio-
cobalt bases, and so, too, did Blomstrand two years later. If we
consider theories of this kind, not as finalities, but as attempts

■i Q 2

11^08 CLARKE: WOLCOTT GIBBS MEMORIAL LECTURE.

to express knowu relations in symbolic forms, Ave Jiiust admit that
Gibbs's conception was xiscful, and served well for the time being.
That it has given way to other views more in harmony with modern
discoveries, is not at all to the discredit of its author. In the later
papers by Gibbs, published in 1875 and 1876, he made good use
of his hypotheses, and described many more ammonio-cobalt com-
pounds. Among them were the salts of an entirely new base,
croceocobalt, in which two nitro-groups were present. In all, five
distinct series were studied, their chlorides being represented, in
modern notation, by the subjoined formulae:

Luteocobalt chloride, Co(NH3)gCl3.

Roseocobalt chloride, Co(NH3)5-HoO-Cl3.

Purpureccobalt chloride, Co(NH3)5-Cl"Cl,.

Xanthocobalt chloride, Co(NH3)3-NOo-Clo.

Croceocobalt chloride, Co(NH3)4(N02)2-Cl.

Gibbss formulae were somewhat different from these, being
doubled, and with the water of roseocobalt regarded not as con-
stitutional, but as crystalline. The simpler, halved expressions were
established by cryoscojoic methods which did not exist when Gibbs
conducted his investigations.

The researches on the platinum metals, published by Gibbs in
the years 1861 to 1864, relate mainly to analytical methods.
Processes for the solution of iridosmine were carefully studied, and
various new separations of the several metals from one another
were devised. Incidentally, a number of new compounds were
prepai'ed, Avhich, with a few exceptions, Gibbs never fully described.
In 1871, however, he published a brief note on the remarkable
complex nitrites formed by iridium, and in 1881 he described a
new base, osmyl-ditetramine, ■Os02,4NH3, together with several of
its salts. These researches were never pushed very far, and were
discontinued for lack of proper facilities. They were, nevertheless,
distinct additions to our knowledge of the platinum group.

I have already mentioned the work done by Gibbs and his
students in the laboratory of the Lawrence Scientific School. This
covered a wide range, partly in developing and perfecting old
analytical methods, partly in devising new ones. There were
improvements in gas analysis, especially in the determination of
nitrogen, and a great variety of analytical separations. I will not
attempt to give a catalogue of these investigations, but will limit
myself to a few of the more noteworthy. A new volumetric method
for analysing the salts of heavy metals was worked out, in which a
metal such as copper or lead was precipitated as sulphide, the acid
being afterwards determined by titration. The estimation of

CLARKE: VVOLCOTT GIBBS MEMORIAL LECTURE. 1309

manganese as pyrophosphate was another of these contributions
to analysis. But the most important of all was the electrolytic
determination of copper, now universally used, which was first
published from Gibbs's laboratory. It is true that a German
chemist, Luckow, claimed to have used the method much earlier,
but so far as I can discover he failed to publish it. Gibbs, there-
fore, is entitled to full credit for a process which was the progenitor
of many others. The entire field of electrochemical analysis was
thrown open by him, and it has been most j^rofitably cultivated.
Gibbs also, during this period of his activity, invented several
instrumental devices of great convenience. The ring burner, and
the use of porous septa when precipitates are to be heated in gases,
are due to him. Furthermore, in co-operation with E. R. Taylor,
he devised a glass and sand filter which was the forerunner of
the porous cones invented by Munroe when the latter was a student
in Gibbs's laboratory. That, in turn, preceded the well-known
perforated crucibles of Gooch, who was one of Gibbs's assistants.
The genealogy of these inventions is perfectly clear.

We come now to the remai'kable series of researches on the
complex inorganic acids, which Gibbs began to publish in 1877,
and continued well into the 'nineties. The gi'ound had already
been broken by others; silicotungstates, phosphotungstates,
phosphomolybdates, etc., were fairly well known, but they were
commonly regarded as exceptional compounds rather than as
representatives of a very general class. In his first, preliminary,
communication upon the subject, Gibbs indicated the vastness of the
field to be explored, and showed that the formation of complex
acids was characteristic of tungsten and molybdenum to an extra-
ordinary degree. The phenomena were general, not special; and
no limit could be assigned to the possible number of acids which
these elements might form.

In his systematic work, following his preliminary announcement,
Gibbs first revised the sodium tungstates in order to determine
their true composition. Then, after preparing a number of
phosphotungstates and phosphomolybdates, he studied the corre-
sponding com^DOunds containing arsenic in place of phosphorus.
He next obtained similar vanadium compounds, and also showed
that the phosphoric oxide of the first known acids was replaceable
by phosphorous and hypophosphorous grovips. Later still, he
replaced the normal phosphates by pyro- and meta-phosphates, and
also prepared complex salts containing arsenious, antimonious, and
antimonic radicles. Stanno-phosphotungstates and molybdates,
platinotungstates, and complex acids containing mixed groups were
discovered, together with analogous compounds of selenium,

1810 CLARKE: WOLCOTT GIBBS MEMORIAL LECTURE.

tellurium, cerium, and uranium. One salt described, a phospho-
vanadio-vanadico-tungstate of barium, bad tbe formula

60WO3,3PoO,„V.A'VOo,18BaO,150H2O,

witb a molecular weight of 2006G. Compared with this substance,
the supposed complexity of most organic compounds becomes
simplicity itself, and their interpretation seems relatively like child's
play. In all, Gibbs described complex salts belonging to more than
fifty distinct series, and did his work in a small private laboratory
with only a single assistant. With greater resources at his
command, what might he not have accomplished ?

In 1898, in his address as retiring president of the American
Association for the Advancement of Science, Gibbs summed up
his views as to the constitution of the complex acids. His pre-
sentation of the subject, however, can hardly be regarded as final.
The problems involved are too complicated to be easily solved, and
much future investigation is needed in order to determine the true
character of these extraordinary substances. Gibbs was a pioneer,
breaking pathways into a tangled wilderness; but the ways are
now open, and he who wills may follow. Possibly some of the
compounds so far obtained were double salts ; others may have
been isomorphous mixtures ; and in some instances phenomena of
solid solution perhaps obscured the truth. By physical methods,
cryoscopic or ebullioscopic, the molecular weights of the salts must
be determined ; their ionisation needs to be studied, and in such
ways their true nature can be ascertained. These methods of
research have been mainly developed since the work of Gibbs was
done; he, therefore, cannot be criticised for not employing them.
Since his time chemists have come to recognise many compounds
as salts containing complex ions, such as, for example, the oxalates,
tartrates, etc., of iron, aluminium, chromium, and antimony with
other bases of lower valency. Even many of the silicates are
easiest to interpret as salts of alumino-silicic acids, although the
physical proof of their nature is difficult to obtain. The con-
stitution of the complex acids is one of the great outstanding
problems of inorganic chemistry.

Although he was distinctively an inorganic chemist, Gibbs did
not entirely neglect organic chemistry. In 1868 he discussed the
constitution of uric acid and its derivatives, and in 1869 he
described some products formed by the action of alkali nitrites
on them. He also produced several memoirs on optical subjects,
such as one on a normal map of the solar spectrum, and another
on the wave-lengths of the elementary spectral lines. Again, he
devoted some time to the study of interference phenomena, and
discovered a constant, which he called the interferential constant,

I

CLARKE: WOLCOTT GIBBS MEMORIAL LECTURE. 1311

that was independent of temperature. One of Gibbs's latest papers,
publislied when he was seventy-one years old, related to that
extremely difficult subject, the separation of the rare earths, a
subject in which he had always taken a deep interest. In this
paper he developed a new method for determining the atomic
weights of the rare-earth metals, which was based upon analyses of
their oxalates. The oxalic acid was determined by titration with
permanganate solutions, and the oxides by ignition of the salts.
.From the ratios between the oxalic acid and the oxides, the
molecular weights of the latter could be computed without reference
to the amount of moisture in the initial substances. This method
has since l)cen employed by others, and especially by Brauner, in
his work on the atomic weights of cerium and lanthanvim. It is
worth noting here that Gibbs had previously taken some part in
atomic weight determinations. Those of Wing on cerium, and of
Lee on cobalt and nickel, were made in Gibbs's laboratory and
under his guidance. Furthermore, Gibbs was one of the earliest
American chemists, if not the first, to accept the modern or
Cannizzaro system of atomic weights, and to use it in his teaching.
His mind was never closed to new ideas. It welcomed light from
all sources.

Gibbs wrote no books and delivered no popular lectures. He
was therefore little known to the public at large, but within scientific
circles he received high honours. He was one of the founders of
the National Academy of Sciences, and at one time its President,
and he also presided over the American Association for the
Advancement of Science. Honorary membership in the German,
English, and American chemical societies, and in the Prussian
Academy, was conferred upon him, and he received honorary
degrees from several universities. His life was that of a devoted
scholar, caring most for research, and indiflfcrent to popularity.
Sensationalism and self-advertising were most obnoxious to him ;
indeed, in these respects, no man could be more fastidious. The
approval of his fellows he fully appreciated, but only when it was
spontaneous and deserved. It must not be inferred from these
remarks that Gibbs was deficient in public spirit, for that would be
most untrue. During the Civil War, from 1861 to 1865, he was
strongly patriotic, and did much to help the Union sfde. The
Union League Club of New York, organised to bring together the
more patriotic citizens of that city, was founded at a meeting
in his house, and is to-day a strong social institution. Gibbs was
also active in the Sanitary Commission, an organisation modelled
iipon the work of Florence Nightingale in the Crimea, and the
foi'erunner of the Red Cross Society of to-day.

Wolcott Gibbs was a man of striking personality, tall, erect, and

1312 HARROP, NORRIS, AND WEIZMANN :

dignified. As with most men of positive character, he had strong
likes and dislikes, but the latter never assumed unworthy form.
To his friends he was warmly devoted, and always ready to help
them in their work with manifold suggestions. His breadth of
mind is indicated by the range of his researches, and his libei-ality
by the way in which he encouraged his students to develop his
ideas. More than one important investigation was based upon
hint-s received from him, and was carried out under his supervision,
to appear lat-er iinder another name. Gibbs never absorbed the
credit due even in part to others, nor failed to recognise the merits
of his assistants in the fullest way. Had he been more selfish,
his list of publications would have lengthened ; but his sense of
justice was most keen, and therefore he held the esteem and
confidence of his co-workers. No man, not even among his
opponents, for such there were, could ever accuse him of unfairness.
He deserved all honour, and his name will live long in the history
of that science to which his life was given.

CXLY. — Some Derivatives of Antliraquinone.

By Dorothy Harrop, Roland Victor Norris, and Charles

Weizmann.

In a previous communication (this vol., p. 279) the authors have
described certain derivatives of naphthacenequinone obtained by
conden,sing 3 : 6-dichlorophtbalic anhydride with a-naphthol by means
of boric acid, the 3 : 6-dichloro-l'-hydroxy-2-/3-naphthoylbenzoic acid
being caused to undergo internal condensation by means of fuming
sulphuric acid, producing 7 : 10-dichloro-l-hydroxynaphthacene-
quinone :

It was found that by boiling this quinone with aniline or toluidine,
the chlorine atoms were replaced by the anilino- or toluidino-residues.
In the present communication the authors have extended their
investigations to the ditnethylanthraquinones, and find that the
reactivity of the chlorine atoms is not restricted to amino-groups, but
that phenol and thiophenol will react quite easily in presence of
alkali, giving rise to the phenyl ethers of hydroxy- and thiol-anthra-
quinones respectively. The diraethylanthraquinoncs which are here
described have been prepared in the usual way by condensing 3 : 6-
dichlorophthalic anhydride with the three xylenes by means ui

SOME DERIVATIVES OF ANTHRAQUINONE 1313

aluminium chloride, furnishing the corresponding dichlorodimethyl-
hei)zoyIbenzoic acids in good yield.

CI ^Q Mo CI ^.Q Me CI ^Q Me

^ ICO.H I j I 'C0,H I J^fe ^ JcOgH

01 ^ CI CI Me

(I.) (11.) (HI.)

On bromination these acids form bromo-substituted derivatives, but
only that derived from (II) has been isolated in the pure state. On
warming the acids in fuming sulphuric ncid in presence of boric acid,
they yield the carrespondiug dichlorodimethylanthraquinones.

CO Me

01 CO Me

(VI.)

All these quinones crystallise well, and the yields are good except in
the case of (V), where the closing of the ring is very difficult, and never
more than 5 per cent, of the theoretical amount has been obtained.
With fuming nitric acid all three quinones form nitro-derivatives ;
(V) and (VI) yield mononitro-compounds, but in the ca^e of (IV) a
dinitro-derivative is obtained.

As previously stated, when boiled with aniline in the presence of
boric acid, or with phenol or thiophenol in the presence of alkali, each
chlorine atom is displaced by the aniline-, pheuoxy-, or phenj'lthiol group
respectively. The dianiiinodimethylanthraquinones are dark blue,
whilst the phenoxy- and phenylthiol derivatives ai'e yellow and dark
red respectively.

The entrance of the auxochromic groups into the anthraquinone
molecule and their influence on the colour of the quinone follow the
general rule. The position of the methyl groups exerts practically no
influence on the colour of the compounds or on the colour of their
solutions in concentrated sulphuric acid, except in the case of the
phenoxy- and phenylthiol compounds. In the former case the
quinone derived from /(-xylene gives in sulphuric acid a much bluer
shade of violet, whereas in the latter the reverse seems to hold good.
The quinone derived from ^j-xylene gives a green coloration in
concentrated sulphuric acid, whereas that from o-xylene gives a blue
solution. The quinone from ??i-xylene also forms a blue solution,
but turns green on gentle warmiug. The influence of the auxochromes
is shown in the following table.

1314 HARROP, NORRIR, AND WEIZMANN :

Colour in

Substance. Colour. sulphuric acid.

Diniethyla nthr;ii |uinones Yellow

Dichloroiiiuieth ylanthraquinones Greenish-yellow Orange-red

Dianiliiiodinietliylantliraquinones Blue Green

Diphcuoxyiliniethjianthranoni's Yellow Violet

Diphenylthioldiniothylanthraquinones Dark red Blue

Experimental.
3 : G- DicIdoro-2' : ?>' -dimethyl-'l-benzoylbemoic Acid (I, p. 1313).

This acid is prepared by condensing 3 : 6-dichlorophtlialic anhydi'ide
and o-xylene in presence of aluminium chloride. One hundred grams
of 2 : 6-dichlorophthalic anhydride, purified by distillation in a
vacuum, are mixed with 150 grams of o-xylene, and 200 grams of
finely powdered aluminium chloride are gradually added. The
reaction soon becomes vigorous, and the mixture assumes a dark red
colour. After the addition of the aluminium chloride, the whole is
heated on the water-bath until hydrogen chloride is no longer evolved
(four hours). The semi-solid mass is then decomposed by ice and
dilute hydrochloric acid, and the excess of o-xylene is removed by
distillation in a current of steam. The dark brown oil remaining
slowly solidifies on cooling. It is purified by dissolving in dilute
aqueous sodium hydroxide, warming with animal charcoal, and de-
composing the alkaline solution by ice and hydrochloric acid, when
dichlorodimethylbenzoylbenzoic acid separates as a bulky, grey
precipitate. After collecting and drying, it is washed with cold benzene
to remove traces of oily products, and finally purified by crystallisation
from glacial acetic acid :

0-1141 gave 0-2478 CO., and 0-0402 H^O. 0 = 59-21 ; H = 3-9,

0-1241 „ 0-1089 AgCl. 01 = 21-72"
C1GH12O3OI2 requires 0 = 59-46 ; H = 3-72 ; 01 = 21-95 per cent.

3 : Q-Dichloro-2' : Z' -dimethyl-2-henzoylhenzoic acid when anhydrous
melts at 181° It is readily soluble in alcohol, and crystallises from
glacial acetic acid in minute, colourless needles. Its sodium salt is
yellow.

When its acetic acid solution is heated with a slight excess of
bromine for twenty-four hour-s on the water-bath, a monobromo-
derivative is produced, but so far this acid has not been obtained in a
pure condition.

5 : 8-Dichloro-l : 2-dimethylanthraquinone (IV, p. 1313),

This is prepared by heating a mixture of the acid just described
(50 grams), boric acid (50 grams), and an excess of fuming sulphuric
acid, containing 10 per cent, of sulphur trioxide, to 120° for ten

SOME DERIVATIVES OF ANTHRAQUINONE. 1315

minutes. The product is poured on ice, boiled, and filtered ; the green
precipitate of the quinone is freed from traces of acid hy boiling with
dilute aqueous sodium hydroxide, filtering, and then washiog with a
little dilute hydrochloric acid.

5 : 8-Dichloro-\ : 2-dvmethi/lanihraquinone crystallises from glacial
acetic acid in greenish -yellow needles, which melt at 269 — 270° :

0-2454 gave 0-5643 COg and 0-0785 HgO. 0 = 62-71 ; H = 3-55.

0-1413 „ 0-1317 AgCl. Cl = 23-04.

■ C1gH10O.2Cl._j requires C = 6297; H = 3-28 ; Cl = 23-25 per cent.

This quinone is readily soluble in benzene or xylene, but only
sparingly so in alcohol. Its solution in sulphuric acid is orange-red.
When warmed with fuming nitric acid for about fifteen minutes and
then poured into water it yields a dinitro-compound.

5 : 8-D{chlorodi7iitro-l : %dimethylanthraquinone crystallises from
glacial acetic acid in pale yellow needles, which melt at 226°. It is
practically insoluble in alcohol or benzene, but readily so in xylene :

0-1085 gave 0-1926 CO., and 0-0216 H,0. 0 = 48-40; H-2-21.

0-1209 „ 7-4 c.c. N./(moist) at 19° and 772 mm. N = 7-14.

0-1352 „ 0-0958 AgCl. 01=17-52.

CicHsO^N.Cl, requires 0 = 48-61; H = 2-02; N = 7-09; 01=17-95

per cent.

5 : 8-DtaniUno-l : %dimethylanthraquino')ie,

(NHPh),OeH2<^^>C6H2Me2,

is formed when 5 : 8-dichloro-l : 2-dimethylauthraquinone, together with
a little boric acid, is boiled with aniline for twelve hours. The
original red solution gradually changes to blue. The solution is then
treated with alcohol and hydrochloric acid, the precipitate collected,
washed free fi-om aniline hydrochloride, and crystallised from xylene,
from which it separates in dark blue crystals. It is readily soluble
in benzene, xylene, or nitrobenzene. Its solution in concentrated
sulphuric acid is green :

0-1003 gave 0*2949 OOg and 0-0501 HgO. 0 = 80-18 ; H = 6-Gl.

0-1106 „ 6-4 c.c. No"(moisfc) at 20° and 757 mm. N = 6-61.
O28H02O2N, requires" 0 = 80-38 ; H = 5-26 ; N = 669 per cent.

5 : ^-Dijihenoxy-Y : 2-dimethylanthraquinone,

is prepared by boiling 10 grams of 5 : 8-dichloro-l : 2-dimethylanthra-
quinone with 10 grams of sodium hydroxide and a large excess of
phenol for twenty minutes. The liquid, which has an orange-yellow
colour, is acidified with hydrochloric acid, and the excess of phenol
removed by distillation in a current of steam, when the diphenoxy-

1316 HARROP, NORRIS, AND WEIZMANN :

quinone is left as a brown oil, which solidifies on cooling. After
drying, it is purified by crystallisation from glacial acetic acid, from
which it separates in yellow needles melting at 214°. It is readily
soluble in benzene, xylene, or nitrobenzene, but sparingly so in alcohol.
In concentrated sulphuric acid its solution possesses a fine violet
colour, which becomes redder on the addition of fuming sulphuric
acid :

0-1243 gave 0-3643 CO^ and 0 0532 H,0. C = 7989; H = 476.

CjgHgoO^ requires C = 80-00 ; H = 4-76 per cent.
5 : d,-Diphenylthiol-\ : 2-dimethylanthraquinone,

is prepared in an exactly similar manner to the above-mentioned
phenoxy-derivative, replacing the phenol by thiophenol :

0-1442 gave 0-3912 CO.^ and 0-0539 H^O. C = 74-00; H = 4-31.

0-2013 „ 0-2113 BaSO^. S= 14-41.

C28H00O2S2 requires C = 74-33 ; H = 4-42 ; S = 14-15 per cent.

5 : ^- Diphenylthiol-\ : 2-dimethylanthraquinone cx'ystallises from
acetic acid in beautiful dark red needles, is readily soluble in xylene
or nitrobenzene, but only slightly so in alcohol. Its solution in con-
centrated sulphuric acid is dark blue.

3 :Q-I)ichloro-2' : i' -dimethyl-2-henzoylhenzoic Acid (II, p. 1313).

This acid is prepared by condensing 3 : 6-dichlorophthalic anhydride
with 7?i-xylene in presence of aluminium chloride as described in the
preparation of 3 : 6-dichloro-2' : 3'-dimethyl-2-benzoylbenzoic acid
(p. 1314), which acid it resembles in properties. It melts at 164°:

01 166 gave 0-2417 CO2 and 0-0303 H2O. C = 59-60 ; H = 3-64.

0-1462 „ 0-1249 AgCl. 01 = 21-80.
C^HioOgClg requires 0 = 59-46; H = 3'72; 01 = 21-95 per cent.

3 : Q- Dichloro-5'-b7'omo-2' : i' -dimel hyl-2-benzoylbenzoic acid is obtained
when the acetic acid solution of the acid just described is heated on
the water-bath with an excess of bromine for twenty hours.

On pouring the solution into water, a sticky, white precipitate is
formed, which is collected, washed with sodium hydrogen sulphite, and
crystallised from xylene :

0-1053 gave 0-1835 OO2 and 0-0285 H^O. 0 = 47-51 ; H = 3-00.

01343 „ 0-1569 AgOl and AgBr. 01 + Br = 37-24.
OigH^OgOUBr requires 0 = 47-77; 11 = 2-73; 01 + Br = 37-54 percent.

3 : P)-I)ichloro-5'-brorno-2 : i'-diinethyl-2benzoylbenzoic acid, crystallises
in small, colourless needles, which dissolve readily in alcohol, benzene,
or xylene. Its sodium, salt is yellow.

SOME DERIVATIVES OF ANTHRAQUINONE. 1317

5 -.S-Dichloro-l : Z-dimethylanthraquinone (V, p. 1313).

This quinone is prepared in a similar manner to the quinone derived
from 0 xylene (p. 1314) by heating 3 : 6-dichloro-2' : 4'-dimethyl-2-
benzoylbenzoic acid with boric acid and fuming sulphuric acid. The
yield, however, is extremely poor, a large quantity of resinous matter
being invai-iably formed. The best results are obtained by using
sulphuric acid containing about 30 per cent, of sulphur trioxide, and
keeping the temperature below 110°. It is also advisable to carry out
the operation with very small quantities (5 grams) at a time. In no
case, however, was the yield more than 5 per cent. The quinone is
puritied by crystallisation from acetic acid, from which it separates in
pale greenish-yellow needles melting at 208°. Its properties are
similar to those of the quinone derived from o-xylene (p. 1315) :

0-1249 gave 0-2879 CO,, and 00392 Hp. 0 = 62-86; H = 3-49.

0-1443 „ 01349 AgCl. 01 = 2311".
Ci,iH,oO.,C1.3 requires 0 = 62-97; H = 3-28; 01 = 23-25 per cent.

On warming this compound with fuming niti'ic acid for fifteen
minutes and pouring the solution into water, a mononitro-derivative is
obtained.

5 : 8-Dichloronitro-l : d-dlniethylanthraquinone crystallises fromacetic
acid solution in yellow needles :

0-1102 gave 0-2198 OO2 and 0-0237 HoO. 0 = 54-4; H = 2-39.

0-0750 ,, 2-8 c.c. N2 at 14° and 749 mm. N = 4-32.

0-1554 „ 0-1264 AgOl. 01 = 20-12.
OieH.p^NOl.^ requires 0 = 54-87; H = 2-57; N = 4-00; 01 = 20-26

per cent.

5 : S-Dianiliyw-l : 'd-dimetlcijlanthraquhione,

is obtained by boiling aniline and 5 : 8-dichloro-l : 3-dimethylanthra-
quinone under the same conditions as those described previously
(p. 1315). It crystallises from xylene in dark blue needles. When
dissolved in concentrated sulphuric acid it forms a green solution :

0-1063 gave 0-3125 00.^ and 0-0514 H,0. 0 = 80-17 ; H = 5-37.

0-1241 „ 7-2 c.c. N2 at 20° and 758 "mm. N = 6-62.

O2SH22O0N2 requires 0 = 80-38; H = 5-26 ; N = 6-69 percent.

5 : S-Diphenoxy-l : 3-diinelht/lanthraquinoue,

{OPh)2C6H2<^^>06H2Me2,

is prepared in exactly the same manner as 5 : 8-diphenoxy-l : 2-
dimetbylanthraquinone (p. 1315). It crystallises from acetic acid in
yellow needles, which melt at 186° :

1318 SOME DERIVATIVES OF ANTHllAQUINONE,

0-1336 gave 0-3904 CO., aud 0-0558 HoO. C- 79-69; H = 4-64.
C.,sH2o04 requires C = 80-00 ; H = 4-76 per cent.

Its solution in concentrated sulphuric acid is reddish-violet.
5 : S-D iphenylthiol-l : 'd-dimethylantltraquhione,

(SPh),CeH2<co>C6H2Me.,

is prepared by boiling thiophenol and 5 : 8-dichloro-l : 3-dimethyl-
anthraquinone in presence of alkali (see p. 1316). It crystallises from
acetic acid in dark led needles, which melt at 207^^. Its solution in
sulphuric acid is blue, but turns green on gentle warming :

0-1136 gave 0-3103 CO.^ and 0-0462 Hp. 0 = 74-49 ; H = 4-52.
0-1879 „ 0-1961 BaSO^. S = 14-32.
CjsHgoOgSg requires C = 74-33 ; H = 4-42 ; S= 14-15 per cent.

3 : 'o-Dichloro-l' : b' -dimethyl-2-benzoylbenzoic Acid (III, p. 1313).

This acid is prepared by condensing 3 : 6-dichlorophthalic acid Avith
p-xylenein presence of aluminium chloride (see p. 1314). It crystallises
from acetic acid in colourless needles melting at 152° :

0-1458 gave 0-3182 COg and 00514 HgO. C - 59*52 ; H = 3-91.
0-1567 „ 0-1375 AgCl. Cl = 21-69.
C^gHi^OgCU requires 0 = 59-46 ; H = 3-72 ; CI = 21-95 per cent.

It forms a bromo- derivative on prolonged treatment with bromine
in acetic acid solution, but, so far, this has not been obtained in a
condition sufficiently pure for analysis.

5 : S-Dichlo7'o-l : i-dimethylanthraquinone (VI, p. 1313).

This is obtained in almost quantitative yield by heating 3 : 6-
dichloro-2' : 5'-dimethyl-2-beuzoyl benzoic acid with concentrated
sulphuric acid containing 10 per cent, of sulphur trioxide.

It crystallises from acetic acid in pale yellow needles melting at
244°. It has similar properties to the two dimethylanthraquinones
already described. Its solution in sulphuric acid is orange-red :

0-1064 gave 0-2449 CO^ and 00333 H.p. 0 - 62-75 ; H = 3-47.
0-1539 „ 0-1453 AgCl. 01 = 23-35.
CVH10O2CI2 requires C = 62-97 ; H = 3-28 ; 01 = 23-25 per cent.

5 : 8-Dichloi-onitro-l : ^-dimethylanthraquinone is obtained by treating
the above compound with fuming nitric acid. It crystallises from
acetic acid in pale yellow needles melting at 243° :

0-1156 gave 0-2321 CO2 and 0'0259 H^O. 0 = 54-75 ; H = 2-49.
0-0S86 „ 3-0 c.c. N, at 19° and 764 mm. N = 3-91.

THE COLOUR AND CONSTITUTION OF DIAZONIUM SALTS. 1819

0-1663 gave 0-1348 AgCl. CI = 20-04.

Ci^HjgO^NCU requires C = 54-87; H = 2-57; N-4-00; 01 = 20-26

per cent.
5 : 8-Dianilino-\ : ^-dimethylanthraquinone,

(NHPh)AH2<co>CoH2Me„

is prepared by boiling the corresponding dichloro-quinone with aniline
iu presence of boric acid (oce p. 1315). It ci-ystallises from xylene in
dark blue needles, and forms a green solution in concentrated sulphuric
acid :

0-1062 gave 0-3122 COo and 0-0572 H.p. C = 8019 ; 11 = 5-35.

0-1503 „ 8-8 c.c. ^^\t 19° and 765''mm, N = 6-65.

CgsHsPaNg requires" C = 80-38 ; H = 5-26 ; N = 6-69 per cent.

5 : 8-Diphenoxy-l : i^-diviethylanthraquinone,

(OPh)2CeH2<^^>C,H2Me2,

is prepared in the same way as the previously described diphenoxy-
derivatives. It crystallises in yellow needles melting at 154°. Its
solution in sulphuric acid is much bluer than the two previously
mentioned diphenoxy-quinones :

0-1045 gave 0-3062 COg and 0-0457 H.p. C = 79-87 ; H = 4-86.
CogHgoO^ requires C = 80-00 ; "h = 4-76 per cent.

5 : %-Diphenylthiol-\ : i^-dimethylanthraqidnone,

prepared as described in the case of the corresponding compounds
derived from o-and ?«-xylene (p. 1316), crystallises in dark red needles.
Its solution in concenti'ated sulphuric acid is green :

0-1263 gave 0-3432 CO. and 0-0484 H.O. C = 74-12 ; H = 4-24.

0-1661 „ 0-1741 BaSO^. 8 = 14-38^

C^gHgoOoSa requires C = 74-33 ; 11 = 4 -42; 8 = 14-15 per cent.

The University,
Manchestek.

CXLVI. — The Colour and Constitutioib of Diazoyiium
Salts. Part I.

By Gilbert T. Morgan and Mary Alcock, B.Sc, A.R.C.S.

In accordance with the hypothesis first put forward by Cain (Trans.,
1907, 91, 1040), diazonium salts must be regarded as substances of a
hemi-quinonoid type, and this view receives confirmation from the
following circumstances : the fact that only aromatic amines can be

1820

MORGAN AND ALCOCK : THE COLOUR AND

diazofciseil, the great reactivity of diazonium salts, the readiness with
which these substances lose their diazo-nitrogen, and the not infrequent
appearance of colour among this class of compounds.

The static para-configuration (II) for diazonium salts has, however,
been adversely criticised by those who contend that substances having
the second nitrogen atom attached to the para-carbon atom of the
nucleus should yield para-diamines on reduction, a result which has
not hitherto been observed. The connexion between the tervalent
diazo-nitrogen and the pai-a-carbon atom can, therefore, scarcely have
the stability generally associated with a single linking.

This criticism is equally applicable to the ortho-quinonoid configura-
tion (I and III) suggested as a possible alternative (Trans., 1907, 91,
1315), for such compounds should, in like manner, yield ortho-
diamines.

This objection is met by the hypothesis put forward by one of the
authors in conjunction with Miss Micklethwait, according to which these
static ortho- and para-configurations may be regarded as successive
phases in the life history of a diazonium salt. It is assumed that the
direction of the third valency of the tervalent nitrogen atom under-
goes a rhythmical change, so that it is dii"ected successively towards
the carbon atoms in positions 2, 4, and 6 in the nucleus * (Trans.,
1908, 93, 618).

1

d-N \

(I-)

N

\

4
(II.)

(HI.)

^

This conception of shifting valency directions has already afforded
an explanation of the chemical reactions of compounds of very varied
type. It forms an essential part of Kekule's hypothesis of the
constitution of benzene, and quite recently has been systematically
employed under the name of " isorropesis " by Baly and his collaborators
as a working hypothesis of the structure of compounds displaying
certain spectroscopic peculiarities.

With the object of gaining further information as to the behaviour
of diazonium derivatives, experiments have been made on benzoyl-

* This dynamic formulation can lie readily illustrated by the simple mechanical
models devised by Mr. A. Clayton to meet this case and also that of the oscillating
bonds of the Kekule formula for benzene.

CONSTITUTION OF DIAZONIUM SALTS. PART I. 1821

y>phenylenediamine and its homologues, inasmuch as these bases furnish
exceptionally stable diazouium salts.

Benzoyl-^;-auiiuobenzencdiazonium hydroxide has already been shown
to yield a nitrite and a carbonate (Trans., 1905, 87, 933), and in this
research the chloride, acetate, and 'perchlorate have been shown to be
stable in the dry state. The last of these is, therefore, remarkably
different from benzenediazonium perchlorate, which is described as
extremely explosive even in a moist condition (Vorliinder, Ber., 1906,
39, 2715).

It might accordingly be supposed that the presence of thep-benzoyl-
amino-group brings about a variation in the contiguration of the
diazonium complex, whereby a more stable molecule results. This
structural variation could only be produced by a migration of the
labile hydrogen atom from the benzoylamino-group, CgH^*CU"NH, to
the diazonium complex, leading to the formation of a salt having the
following formula : CjjHg-CO-NICgH.^IN.HCl.

This possibility is now quite excluded, because it has been shown that
the bases in which this hydrogen is replaced by methyl and ethyl give
rise to diazonium salts having the same chemical properties as those
containing the group CgHj'CO'NH.

a.s.-Benzoyhnelhyl-'^-jyhenylenedianmie and sm-henzoylethyl-p-pheni/lene-
diamhie have been prepai'ed and studied from this standpoint. These
bases are more fusible than benzoyl-/)-phenylenedianiine, and a
similar fall in the melting point is noticed in their corresponding
derivatives. This difference is most pronounced in the case of the
diazonium salts, for whereas the benzoyl-^>aminobenzenediazonium
salts are crystallisable solids, the benzoylalkyl-/?-aminobenzenediazonium
salts, with few exceptions (for example, the molybdates and tungstates)
are oily at the ordinary temperature. In other respects, these solid
and oily diazonium salts are similar ; they are colourless and stable when
dry, and undergo similar transformations on treatment with alkalis.

Sodium hydroxide and these diazonium salts interact in accordance
with the following equation :
2C6H5-C0-NX-C,H4-N2C1 + 2NaOH = 2NaCl + N2 + H2O +

C.jHs-CO-NX-CjjH^-Ng-O-CgH^-NX-CO-CgHs,
where X - H, CH3, or CgH^.

With ammonia the course of the change depends, to some extent, on
the nature of the radicle X in the foregoing formula, for, when this
symbol represents CHg or C2H5, a diazoamine is the main product :

2C6H5-C0-NX-C^H4-N.,C1 + SNHg = 2NH4CI + ^.^ +

CoHs-CO-NX-CeH^-Na-NH-CgH^-NX-CO-CeHj.

When X is hydrogen, the reaction leads partly to the diazoamine,
but also to the diazo-oxide. The nitrogen eliminated in these decom-
VOL. XCV. 4 K

1822 MORGAN AND ALCOCK : THE COLOUR AND

positions is set free as such, aiul no trace of niti-ite could be detected.
These diazonium salts differ, therefore, from ^j-nitrobenzenediazonium
chloride, which has recently been found to regenerate nitrite under
treatment with alkalis {Ber., 1909, 42, 881).

Summary.

These experiments show that the diazonium salts of benzoyl-/)-phenyl-
eneuiaminc and the as-benzoylalkyl-/>-phenylenediamines are similarly
constituted, so that their stability must be attributed to the inti^oduc-
tion into the nucleus of the heavy substituent CgHr/CO'NX (where
X is H, CH3, or C0H5), and not to any modification of the ordinary
diazonium configuration. When treated with aqueous sodium hydr-
oxide and ammonia, these diazonium salts lose half their diazo-nitrogen,
yielding diazo-oxides and diazoamines respectively.

Experimental

Preparation of the 1^-Alki/l Homologues of Benzoyl-^^-phenylene-

diamine.

a,s,-Benzoylmethyl-'^-])henyIenediainine, COPh-NMe'C^H^'NHo. —
Metbyl-^^-nitroaniline, obtained by methylating 4 : 4'-dinitrodiazo-
aminobenzene and decomposing the resulting alkyldiazoamine with
concentrated hydrochloric acid (Meldola and Streatfeild, Trans., 1888,
53, 667), was benzoylated with benzoyl chloride in boiling toluene
(compare Meldola and Salmon, Trans., 1888, 53, 776), and the
benzoylmethyl-;;-nitroaniline thus produced was reduced with iron
filings and very dilute hydrochloric acid, the following quantities
being convenient proportions for this experiment : 12 grams of nitro-
compound, 750 c.c. of water, 6 c.c. of concentrated hydrochloric acid,
and 15 grams of iron filings. After one hour's heating, the mixture,
rendered distinctly alkaline with sodium carbonate, was rapidly
filtered while hot, and the residue of iron and iron oxide was repeatedly
extracted with hot water. The diamine separated in colourless
needles, the yield being about 87 per cent. When crystallised
successively from toluene and light petroleum (b, p. 80 — 100°), the
base, which is only very sparingly soluble in the latter solvent, melted
at 153—154° :

0-1814 gave 0-489G COg and 0-10^9 B.f>. C = 7360 ; H = 6-43.

0-3349 „ 36-6 c.c. N2 at 20° and 748-4 mm. N- 1231.
Cj^Hj^Ng requires 0 = 74-33; H = 6-19 ; N = 12-39 per cent.

SiH- Benzoylethyl - p - phenylenediamine, COPh 'NEt • Cj^H^'NHg. — ■

Benzoylethyl-/3-nitroaniline, prepared by the method already employed
for benzoylmetliyl-p-nitroaniline, was also reduced in a similar manner.

CONSTITUTIOX OF DIAZONIUM SALTS. PART I. 1 S23

The resulting base resembled the foregoing diamine, and was
crystallised successively from water, benzene, and light petroleum ; it
then separated in colourless needles, and melted at 117"' :

01577 gave 04372 CO., and 00956 H.,0. C = 75-61 ; H = 675.
0-2594 „ 26-3 c.c. N, at 23^^ and 773 mm. N = 11-66.

CisKjgONj requires C = 75-00 ; H = 6-67 ; N = 11-67 per cent.

as-Benzoylethyl/>phenylenedianiine and the foregoing base are
very sensitive to the action of water or moist solvents, particularly in
the presence of alkalis. In these circumstances they darken very
perceptibly, this action taking place more readily in the presence of
light. Benzoyl-;>phenylenediamine is itself oxidised with similar
readiness, and the colourless preparations required for the following
experiments were obtained by crystallisation from dry solvents, such as
benzene, toluene, and light peti-oleum.

TIte Diazonium Salts of Benzoyl-^-pJienylenedianiine and its
as-'N-Alkyl Homologues.

Benzoi/l-Y}-phe7ii/lenediamine /i?/<i?-oc74^ortcZe,COPh*NH'C^;H^'NH.,,HCl,
is a white solid obtained by passing hydrogen chloride into a warm
solution of the base in benzene or toluene :

0-3314 gave 0-1861 AgCl. CI = 1390.

CjgH^gON.^Cl requires CI = 14-29 per cent.

This salt is insoluble in ether, but dissolves readily in alcohol or
water. When diazotised with amyl nitrite in glacial acetic acid, ether
precipitates benzo>/l-]p-aminobenzenediazo7iium chloride,

COPh-NH-CeH^-N.^Cl,
as a colourless, crystalline solid very soluble in water or alcohol, the
aqueous solution having a neutral reaction to litmus :

0-2028 gave 0-1089 AgCl. CI = 13-29.

CjgHjgONgCl requires Cl= 13-68 per cent.

The dry salt decomposes at about 139°, and when boiled in aqueous
solution it evolves nitrogen and yields benzoyl-p-aminophenol (m. p.
206^). The corresponding diazonium nitrate obtained from this
chloride and potassium nitrate by double decomposition separates in
lustrous, colourless crystals.

Benzoyl-p-aminobenzenediazonium acetate, COPh'NH'CgH^'Ng'OAc,
is obtained by diazotising with amyl nitrite a glacial acetic acid
solution of benzoyl -/;-phenylenediamine and precipitating with dry
ether. As thus obtained the diazonium acetate is a colourless,
crystalline substance, which turns yellow and then changes to brown on
exposure to the atmosphere :

4 R 2

1824 MORGAN AND ALCOCK : THE COLOUR AND

01 181 gave 143 c.c. N.^ at 21° aud 7665 mm. N = 13-91.
Cj^H^gOgNg requires N = 14*84 per cent.

Benzoyl-^-aminohenzenediazonium jjerchloraie, obtained from the
diazonium chloride aud potassium perchlorate in warm aqueous
solution, crystallises on cooling in colourless needles, which turn yellow
on exposure to light and air. This salt explodes on heating or on
percussion :

Found, N = 11-70. Ci3HioO,.,N3Cl requires N= 12-98 per cent.

Benzoyl-paviinobenzenediazoniurn sulphate, prepared in the same way
as the chloride, is precipitated in colourless crystals by ether. The
protluct appeared to be a mixture of normal and acid sulphates, the
estimations of sulphur and nitrogen both giving numbers in accordance
with this view.

The foregoing diazonium salts are all colourless when freshly
prepared from pure benzoyl-p-phenylenediamine, but become coloured
on exposure to the atmosphei'e. They couple readily with alkaline
/5-naphthol, giving rise to benzoyl-jt)-aminobenzeneazo-/3-naphthol.

The diazonium chloride reacts with potassium chromate,
potassium ferricyanide, and barium platinocyanide, giving rise to yellow,
crystalline, sparingly soluble diazonium salts. The diazonium tung-
state and molybdate of benzoyl-^j-phenylenediamine, unlike the corres-
ponding salts of the iV-methyl and i\^-ethyl bases, are very unstable,
and cannot be preserved ; the diazonium azide is a sparingly soluble,
white substance, which rapidly evolves nitrogen.

Benzoyl -^ - aminodiazohenzene cyanide, COPh'NH'CgH^'Ng'CN,
produced by the interaction of molecular proportions of the diazonium
chloride and potassium cyanide in aqueous solution, separates as an
orange-coloured precipitate, which is quite stable on drying :

0-1823 gave 0-4457 COo and 00792 H^O. 0 = 66-68 ; H = 4-52.

0-2197 „ 43-8 c.c. Ng at 24-5° and 768 mm. N" = 22-55.
Cj^HjoON^ requires 0 = 67-20; H = 4-00; N = 22-67 per cent.

Only this modification of the diazo-cyanide could be obtained ;
it does not couple with alkaline /3-naphthol.

Diazonium Salts of the as-Benzoylalkyl-p-phenyle7iediamines.

The diazonium salts from as-benzoylmethyl-;;-phenylenediamine and
as-benzoylethyl-^>phenylenediamine and the commoner acids are oily
suVj.stances. The diazonium chlorides are produced by dissolving the
base in glacial acetic acid, passing in a slight excess of hydx'ogen
chloride, and adding amyl nitrite to the cooled solution. The addition
of dry ether determines the precipitation of the diazonium chloride as
a viscid, colourless oil.

Diazotisation with ethyl nitrite gives a similar result. The least

CONSTITUTION OF DTAZONHJM SALTS. PART I. 1325

coloured products are ol)tained by diazotising with dry reagents in
the dark, as the newly prepared compounds are very sensitive to light
and moisture. The diazonium sulphates and acetates are also viscid
oils. With the object of obtaining solid diazonium salts of these two
bases, the diazonium chloride was treated in aqueous solution with
the alkali salts of a large selection of inorganic and organic acids.
These attempts were unavailing, except in the case of the molybdates,
tungstates, phosphomolybdates, and phosphotungstates, when solid,
colourless diazonium salts were precipitated.

Benzoylmethi/l-Y)-aminohenzenediazonium rnolijbdate,

COPh-XMe-CfiH^-Ng-HMoO^/HgiMoO^,
was obtained as a white precipitate from benzoylmethyl-^j-amino-
benzenediazonium chloride and sodium molybdate iu aqueous solution :

0-1424 gave 0-0722 M0O3. Mo = 33-80.

CJ4HJ5O9N3M0.2 requires Mo = 34-22 per cent.

When dried over phosphoric oxide, this substance retained its white
colour for an indefinite time. The corresponding diazonium tungstate
was similarly prepared, but owing to its greater solubility in water or
aqueous sodium tungstate it was not isolated in a state of purity.

Benzoylethyl-'^-aminohenzenediazonium molybdate,

COPh-NEt-C^H4-N2-HMo04,H2Mo04,
was also obtained as a white precipitate :

0-3421 gave 19-2 c.c. N2 at 25° and 771 mm. N = 6-36.
0-1291 „ 0-0651 M06.,. Mo = 33-62.

CijHj-O^NgMog requires N = 7-30 ; Mo = 33-39 per cent.

The corresponding tungstate was obtained as a white precipitate,
which, owing to its greater solubility, could not be completely freed
from sodium tungstate.

The diazonium salts of the two alkylated benzoyl-^^-phonylene-
diamines, whether solid or oily, couple I'eadily with alkaline
)8-naphthol.

Benzoylmeihyl-Tp-aminobenzeneazo-^-naphthol,

COPh-NMe-CeH^-N./CjoHg-OH,
is insoluble in water, but dissolves readily in alcohol, from which
solvent it separates in dark crimson crystals with a gi-een reflex ; its
melting point is 152° :

0-1739 gave 16-5 c.c. R^ at 20-5° and 750 ram. N = 10-69.
C23Hjc,02N3 requires N = 11-02 per cent.

Benzoylethyl-'^-aminobenzeneazo-ji-naphthol,

COPh-NEfCeH^-Ng-CioHg-OH,
is a scarlet-i^ed compound, crystallising somewhat indefinitely from
acetic acid, alcohol, or ethyl acetate, and melting at 174 — 175" :

1826 MORGAN AND ALCOCK : THE COLOUR AND

0-2695 save 26-4 c.c. N., at 20^^ and 764 mm. N = 11'27.

CojHjiOoN.^ requires N= 10'63 per cent.
These azo-derivatives develop deep purple colorations with
concentrated sulphuric acid.

Diazoamines from Be^izoyl-p-phenylenediamine and its 'iii-Alkyl

Ilomologues.

Dibenzoyl-i : i'-diaminodiazoaminohenzene,

COPh-NH-C6H^-N2-NH-CgH4-NH-COPh.
— This compound was obtained by the interaction of benzoyl-
;;-phenylenediamine and its diazonium chloride, the former being
dissolved in alcohol and the latter in water. A development of
colour indicates the production of the diazoamine, and the product is
deposited as an orange-brown precipitate on the addition of sodium
acetate, which decomposes rapidly in contact with aqueous solutions.
When quickly collected and dried it decomposed at 186°:

0-1058 gave 14-(') c.c. ^2 at 20° and 767-6 mm. N = 15-95.
CgHg^OgNg requires N = 16-09 per cent.

Although insoluble in water, the diazoamine dissolved readily in
alcohol.

Dibenzoyldimethyl-i : A'-diaminodiazoaminobenzene,

COPh-N'(CH3)-CgH,-N2-NH-CeH,-NMe-COPh.
— The oily benzoylmethylaminobenzenediazonium chloride was dissolved
in water and added to an alcoholic solution of as- benzoylmethyljo-
phenylenediamine. The mixture remained clear, and the diazoamine
was slowly precipitated by the addition of aqueous sodium acetate.
The product was a pale yellow substance, readily soluble in alcohol,
and decomposing at 146° :

0-1699 gave 21-7 c.c. N, at 19-2° and 764-3 mm. N = 14-77.
CgsHgrjOgNg requires N= 15-12 per cent.

Dihenzoyldiethyl-i : \:' -diaminodiazoaminohenzene,

COPh-NEfC(.H4-N2-NH-C,H4-NEt-COPh.
— This diazoamine i-esembled the preceding compound, and was produced
in a similar manner ; it decomposed at about 104° :

0-2289 gave 27-4 c.c. N, at 19-7° and 764-9 mm. N= 13-80.
^30-'^29^2^.'i requires ]Sr= 14-26 per cent.

These diazoamines were resolved into their generators on treatment
with cold concentrated hydrochloric acid, the presence of the diazonium
chloride being detected by the interaction with alkaline /? niphthol.
The diazoamines themselves do not couple with this reagent.

CONSTITUTION OF DIAZONIUM SAI/PS. PAIJT I. 1 f^2 1

Interaction of the Foregoing Diazonium Sails with Aimnonia and
Soditim Ili/droxide.

1 . Benzoi/l-p-aminobenzenediazoniuni Chloride.

(a) Action of Aqueous Sodium Hydroxide. — The addition of this alkali to
an aqueous polutionof thediazoniumchlorideproducesa yellow coloration,
and gradually a brown solid separate.-^, this change being accompanied
by the evolution of nitrogen. After several hours the generation of gas
ceases, and nn electrolyte, such as sodium chloride or acetate, is added to
coagulate the colloidal precipitate. The product is collected after
twelve hours, and is then sufficiently granulated to be washed without
dissolving again to a colloidal solution. The dried diazo-oxide is very
easily electrified ; it decomposes indefinitely at 162°, and dissolves
readily in alcohol, but does not crystallise easily :

0-1269 gave 0-3298 CO2 and 0-0608 H^O. C = 70-87 ; H = 5-32.

0-1868 „ 19-8 c.c. Ng at 20° and 754 mm. N= 12-03.

CaeHgoOgN^ requires C = 71 -57; H = 4-59; N= 12-84 per cent.

(b) Action of Ammonia. — The interaction of ammonia and 'benzoyl-
;)aminobenzenediazonium chloride in aqueous solution gives rise to a
change similar to that observed in the reaction with sodium hydroxide,
but in this case the yellowish-brown product is a mixture of diazo-
amine and diazo-oxide, decomposing at about 135°. The nitrogen
estimations were made on different preparations :

0-1462 gave 0-3772 CO, and 0-0752 H2O. C = 70-34 ; H = 5-71.

0-2041 „ 24-8 c.c. Ng at 22° and 766-7 mm. N = 13-89.

0-1038 „ 13-1 c.c. N2 ,,20° „ 742 mm. N = 14-09.
The diazoamine, Co.HjjOgN',, requires C = 71 -73; H = 4-83; ISr = 16-09
per cent., whilst the diazo-oxide should contain 12-84 per cent,
of nitrogen.

These experiments with sodium hydroxide and ammonia were
repeated in the volumeter, when it was found that in the former case
1-7 atoms, and in the latter TB atoms, of nitrogen were liberated from
two molecular proportions of the diazonium chloride.

2. Benzoylniethi/l-'paminobenzenediazonium Chloride.

(a) With Sodium Hydroxide. — The alkali determined the gradual
separation of an orange- brown solid from the aqueous solution of this
diazonium salt, the change being accompanied by the evolution of
nitrogen. The product was left to coagulate, and then collected and
dried. It was soluble in alcohol, but did not crystallise readily.
Analysis showed that the substance was a diazo-oxide :

1328 THE COLOUR AND CONSTITUTION OF DIAZONIUM SALTS.

0a233 gave 0-32G8 CO2 and 0-0623 H2O. C- 72-30 ; H = 5-71.

0-1072 „ 11-6 c.c. No at 24° and 759 mm. N = 12-11.
CggHg^OgN^ requires C = 72-41 ; H = 5-17 ; N= 12-07 per cent.

The diazo-oxide decomposed indefinitely at 145°.

(b) With Ammoyiia. — The addition of ammonia to the solution of the
diazonium chloride leads to the production of a bright orange precipi-
tate, which decomposed at 146°, and was apparently identical with the
diazoamine obtained synthetically (p. 1326) :

0-1292 gave 0-3426 COg and 0 0674 HgO. 0=72-31 ; H = 5-80.

0-2643 „ 34-2 c.c. Ng at 24° and 763 mm. N = 14-55.
CasHoANg requires 0 = 72-56 ; H = 5-40; N = 15-12 per cent.

3. Benzoi/lethi/l-^^-aminohenzeoiediazonium Cldoride.

(a) Witlt. Sodium Hydroxide. — The addition of the alkali to an aqueous
solution of 'the diazonium salt gave rise to the evolution of nitrogen (one
molecule from two molecules of salt) and the formation of a brown pre-
cipitate, which was soluble in alcohol, ether, or benzene.

This diazo-oxide decomposed at about 90° :

01264 gave 0-3425 00^ and 0-0672 H2O. 0 = 73-87 ; H = 5-91.
0-2157 „ 21-5 c.c. N2 at 21° and 743 mm. N = 11-09.
OgoHogOgN^ requires 0 = 73-16; H = 5-69j N = 11-39 per cent.

(b) With Ammonia. — In this case the product was probably identical
with the diazoamine obtained synthetically (see p. 1326). This pre-
paration, which decomposes at about 99°, was soluble in alcohol,
ether, or benzene ; it did not, however, crystallise readily from any of
these solvents :

0-1047 gave 0-2792 OO2 and 0-0584 HgO. 0 = 72-73 ; H = 6-20.

0-12.30 „ 0-3282 OO2 „ 0-0683 HoO. 0 = 72-78 ; H= 6-17.

0-5139 „ 62 c.c. N, at 23° and 757-5 mm. N= 13'55.
O30H29O2N5 requires" 0 = 73-31 ; H = 5-91 ; N = 14-26 per cent.

Although these diazoamines and diazo-oxides were not produced in
a definitely crystalline condition, nevertheless satisfactory analytical
results were obtained from the thoroughly dried substances, owing to
the fact that in every case very carefully purified base was employed
in their preparation.

Neither the diazoamines nor diazo-oxides coupled directly with
alkaline ^-naphthol, but when previously treated with mineral acid
(especially hydrochloric acid in glacial acetic acid solution) the
presence of a diazonium chloride was indicated by the azo-condensation
with the /3-naphthol.

In the reactions with sodium hydroxide, the amount of nitrogen
liberated was measured in the volumeter, and found to correspond

FENTON AND WILKS : ISOIMINAZOLOXE. 1829

with one molecular proportion of the gas from two molecules of
diazonium salt. The mother liquors were carefully tested for nitrite,
but in no case could any bo detected. Half the nitrogen originally
present in the diazonium salt is liberated as such, the remainder being
present in the diazo-oxide.

Royal College of Science, London,
SouTir Kknsinoton, S.W.

CXL VI I. — isolminazolone.

By Henry John Horstman Kenton and William Arthur
Reginald Wilks, B.A,

Several observations have already been recbrded on the condensa-
tion of diliydroxymaleic acid with organic bases. In the examples
so far studied, the changes take place with elimination of either
one or two molecules of carbon dioxide, so that the resulting
products may be regarded as if they were derived from either
tartronic semi-aldehyde (hydroxypyruvic acid or dihydroxyacrylic
acid) or from glycollaldehyde.

Thus, the action of phenylhydrazine yields, in the first place,
Nastvogel's osazone, CH(:NoHPh)-C(:NoHPh)-COoH. and after-
wards, the dihydrazone of glyoxal, CH(:NoHPh)-CH(:N2HPh).
With ammonia, in aqueous solution, the result is pyrazine-2 : 5-
dicarboxylic acid, and the formation of this substance from
tartronic semi-aldehyde is easily intelligible (compare Trans., 1905,
87, 808).

When dihydroxymaleic acid is oxidised by mercuric chloride,
or by ferric salts, the initial product is mesoxalic semi-aldehyde,
and this readily condenses with carbamide, with loss of carbon
dioxide, to give glycoluril. There is some jDrobability that in
this case the initial product is glycolurilcarboxylic acid,
C4H502N4'COoH, which differs in composition from uric acid by
one molecule of water. It appeared to be a matter of interest,
therefore, to study the condensation of dihydroxymaleic acid itself
with carbamide in the hope of obtaining a purine derivative,
possibly, for example, an isomeride of xanthine. It is expected that
with certain modifications of detail it may yet be possible to attain
this object ; the direct experiments so far carried out have, however,
yielded a different result, the nature of which is briefly described in
the present communication.

When an intimate mixture of anhydrous dihydroxymaleic acid

1880 FENTON AND WILKS : ISOTMINAZOLONE.

(1 mol.) and dry carbamide (2 mols.) is heated on a water-bath
for about two hours, a rather vigoroiis reaction takes place in
the first instance, carbon dioxide and ammonia being evolved in
abundance, with considerable frothing of the mixture. A colour-
less, transparent liquid eventually result-s, which sets to a glassy
solid on cooling; this dissolves very easily in water, but only to
a limited extent in absolute alcohol, and proves to be a mixture
of at least two compounds. If this product is repeatedly extracted
with boiling alcohol, the alcoholic solution on evaporation leaves
a somewhat gummy residue, which, when treated with small quan-
tities of cold water, leaves a mass of transparent crystals. These
are very sparingly soluble in cold water, but dissolve easily in
hot water, from which the substance separates in large, lustrous,
and well-defined pyramids. When heated, they darken at about
225°, and melt completely at 245°.

Dr. A. Hutchinson has very kindly undertaken the examination
of these crystals, and the following is his report :

System. — Tetragonal, probably holohedral.

c' = 0-7063.

Forms present : aJlOO} quite small and not found on all crystals,
jo[lllj large. Owing to the predominance of the form p, the crystals
are of pyramidal octahedral habit. The crystals are remarkable in
that the angle ap= 100 : 111 is 60°. Hence it follows that the angle
;j/=lll : Til is 90°.

Optically the crystals are uniaxial and negative.

Aqueous solutions of this substance give an intense blood-red
colour with ferric chloride; when heated with hydrochloric acid
and a drop of hydrogen dioxide, a beautiful pink colour is obtained.
The most striking reaction, however, is obtained when a solution
of the substance is evaporated to dryness on a water-bath with
chlorine water, or with hydrochloric acid and a trace of potassium
chlorate. The residue so obtained has a brilliant pink colour, and
this, when treated with ammonia, is changed to violet. Sodium
hydro.xide changes it to a bright rose-red.

This behaviour so closely resembles that of uriC acid and of
certain other purine derivatives that the authors were, not un-
naturally, inclined in the first instance to infer that a compound
of this nature had been obtained. It is considered probable that
some of the older observers may, in fact, have been dealing with
the substance now described when they assumed, from the colour
reaction mentioned, the presence of uric acid.

The analytical results clearly demonstrate, however, that the
substance is a condensation product of carb3.mide and a compound
containing two atoms of carbon :

FENTON AND WILKS : ISOTMINAZOLONE. 1331

T. 0-1237 gave 01951 COg and 0-0552 11,0. 0 = 43-01 ; H = 4-95.

II. 01214 „ 34-6 c.c. 1^2 at 16° and 766"mm. N = 33-74.
C3II4ON0 requires 0 = 42-85; H-4-76; N = 33-33 per cent.

Molecular- weight determinations by the cryoscopic method, using
acetic acid as solvent, gave the following result :

01281 in 17-31 acetic acid gave A^=-0-378. M.W. = 75.

01931 „ 17-31 „ „ A«= -0-569. M.W. = 76.

O3H4ON2 requires M.W. = 84.

The known substances which have this molecular formula are
the following: Ruhemann's pyrazolone (m. p. 156°), Rothenberg's
pyrazolone (oil), cyanoacetamide (m. p. 120°), methylparacyano-
formamide (m. p. 260°), acetylcyanamide (syrup), Angeli's keto-
diazopropane (oil), Letsche's hydroxypyrazole, Abel's compound
from epinephrin (not isolated), and lastly, Marckwald's
/i-iminazolone (Ber., 1892, 25, 2357). With the exception of the
last-named comjDOund all these substances are obviously excluded
by their properties or mode of formation. (The colour reaction
with ferric chloride did, indeed, suggest the possibility that the
substance might be pyrazolone, but comparison with a specimen
kindly supplied by Dr. Ruhemann showed that there is no real
resemblance.)

Marckwald (with Ellinger) obtained /x-iminazolone by heating
the hydrochloride of aminoacetal in concentrated aqueous solution
with slight excess of potassium cyanatc ; a crystalline product
melting at 105° is thus obtained, which proves to be acetalyl-
carbamide, NHo-C0-NH-CHo-0H(0Et)2; this, when dissolved in
water and heated with a few drops of sulphuric acid, yields the
iminazolone. The change is represented in the following way, the
acetal of hydantoic aldehyde being an intermediate stage:

^^^ .NH, „^ CO-NH-CH
00<^ = TI 0+1 I

^NH-OH:OH-OH ^ NH OH*

The possibility of the tautomeric formula

^^^ ^, NH-CH

is also suggested. This product is described as indistinctly
crystalline, easily soluble in hot water, and as possessing weakly
acidic and basic properties; it decomposes above the boiling point
of concentrated sulphuric acid. No mention is made of any colour
reactions.

The mode of formation of the comjDOund now obtained by the
present authors would at once suggest that it has the constitution
which Marckwald assigns to his /x-iminazolone. It might be
supposed, for example, that the initial stage consists in the

1382 FENTON AND WILKS : ISOIMINAZOLONE.

formation of glycollaldeliyde, and that this then condenses with
carbamide. Or, that dihydroxyacrylic acid is first produced,
which by condensation with carbamide gives iminazolonecarboxylic
acid, and that the latter subsequently loses carbon dioxide :

C(CO,H)-OH _ CH-OH

C(C02H)-0H ~"^ C(C02H)-0H ""^

C(C02H)-NH^ ~~^ CH-NH-^

The latter view appears to be more probable, since experiments
made with pure glycollaldehyde and carbamide have so far failed
to give the product in question under conditions similar to those
employed in its formation from dihydroxymaleic acid.

It appeared desirable, therefore, to make a close comparison
between this product and Marckwald's compound, especially as
the properties seemed to differ notably in certain respects. The
authors have been enabled to make this comparison owing to
the kindness of Professor Marckwald, who has supplied them with
a small specimen of ^-iminazolone. As a result, it is found that
the two compounds are markedly different; rejoeated purification
fails to show any distinct crystalline form of ju,-iminazolone, and
no acetyl compound could be obtained from it by the treatment
mentioned below. It does, however, show faint indication of the
colour reactions referred to, and, since Professor Marckwald does
not guarantee that the specimen he sends is the same as the
product analysed, the question as to identity cannot be con-
clvisively settled. Owing to the very considerable difference in
properties observed, the present authors consider that for their
product the title isoiminazolone is perhaps the most appropriate.

Acetyl Derivative. — When the substance just described is heated
for a few minutes with excess of acetic anhydride, and the excess
of the reagent is then removed by distillation, a residue is left
which, on cooling, sets to a crystalline mass. This, when re-
crystallised from ether, is obtained in silky needles which melt
at 106°:

0-1471 gave 0-2593 CO2 and 00662 HgO. C = 48-07; H = 5-00.
CaHsO^yCHg-CO) requires C = 47-62; H = 4-76 per cent.

In addition to isoiminazolone, the condensation of dihydroxymaleic
acid with carbamide may give rise to at least three other products :

(a) The mixture obtained by heating the substances together
in the proportion of two molecules of carbamide to one of the acid
is extracted with alcohol in the manner described above in order
to obtain the isoiminazolone. The residue is extremely easily

FENTON AND WILKS : ISOIMINAZOLONE. 1333

soluble in cold water, and if the aqueous solution is poured into
an excess of alcohol, a very voluminous, white precipitate is
obtained, which appears, under the microscope, to be indistinctly
crystalline. After repeated purification by solution in water and
precipitation with alcohol, this product gives no colour with ferric
chloride, but if kept for some days it gives a colour corresponding
with that produced by isoiminazolone, although it is much less
intense. When boiled with barium hydroxide, a bulky, brown
precipitate separates, and the filtrate, after neutralisation, now
gives a fairly intense blood-red colour with ferric chloride.
Analysis of this product, dried in a vacuum desiccator, gave
C = 35'l, H = 5'59, N = 26"8 per cent. Other specimens, however,
prepared in a similar way, gave somewhat different numbers, and
it is therefore rather doubtful whether the product is a definite
substance. The numbers mentioned correspond fairly well with
the formula CsHgOoNo, which requires C = 35-3, H-5-88, N = 27-4
per cent. ; it is therefore not improbable that the product consists
essentially of hydantoic aldehyde, NHo'CO-NH-CHo-CHO, but
that, owing to the instability of this compound, the products
analysed had a somewhat variable composition.

(6) When dihydroxymaleic acid and carbamide are heated
together in equal molecular proportions, a certain amount of
tsoiminazolone is produced, and may be extracted as before from
the mixture. But in this case the principal product is a substance
which dissolves very easily in hot water, and immediately separates
on cooling as a milky, colloidal suspension. The mixture remains
in this condition even after keeping for twenty-four hours or
longer, but coagulation almost immediately takes place on the
addition of a minute quantity of an electrolyte, such as ammonium
chloride. The solid so obtained appears to be amorphous, and is
practically insoluble in cold water; its solutions give no colour
with ferric chloride.

(c) When dihydroxymaleic acid and carbamide are heated in
aqueous solution with a few drops of concentrated hydrochloric
acid, a dark brown powder separates, which dissolves in concen-
trated hydrochloric acid, giving a red solution. This colour is
intensified if an oxidising agent, such as hydrogen dioxide, is
added, whereas reduction with zinc and dilute acid destroys the
colour. Addition of hydrogen dioxide to the reduced solution
immediately restores the colour, and the operations may be
repeated almost indefinitely without material diminution of the
colour intensity. The same brown substance is obtained if glycoll-
aldehyde is condensed with carbamide in a similar way, and the
colour effects mentioned may serve as a fairly delicate test for the

1334 FENTON AND ROBINSON:

identiticatioii of glycoUaldchyde or of substances which give rise
to it on decomposition.

It is the intention of the authors to make a further investigation
of the various products here mentioned when sufficient material
can be prepared.

The principal part of the exj^ense incurred in carrying out this
investigation has been defrayed by means of a grant kindly supplied
by the Government Grant Committee of the Royal Society.

UxivEHsiTY Chemical Labouatoiiy,

CaMB11I[)GE.

CXLVIII. — Homologues of Furfuraldehyde.

By Henry John Hokstman Fenton and Fred Robinson, B.A., B.Sc.

It has been shown in previous communications (Fenton and Gostling,
Trans., 1899, 75, 423; 1901, 79, 807) that the chloro- and bromo-
derivatives of methylfurfuraldehyde are readily obtained by the action
of the corresponding halogen acids on keto-hexoses or on cellulose.
The yield from these carbohydrates is about 20 per cent, of the
theoretical amount, whereas the aldo-hexoses give i-ise to mere ti'aces
only. The halogen atom in these compounds is extremely reactive,
the interaction with silver nitrate, for example, being quantitative
and practically instantaneous ; when boiled with water in presence of
barium carbonate, they are completely hydrolysed, yielding the
hydroxy-derivative. Finely divided metallic silver readily removes
the halogen from the bromo-derivative, the residual groups uniting to
form difurylethanedialdehyde. Treatment with sulphurous acid con-
verts the halogen compounds into a substance having the molecular v
formula CjjHgO^, to which the constitution of methylfuril is pro- i
visionally assigned. This compound shows remarkable colour reactions '
with primary amines, with carbamides, and with strong bases, and i,
various applications of these reactions have already been suggested
(Proc. Camb. Phil. Soc, 1906, 13, 298). The action of malonic ester
on the halogen derivatives in presence of alcoholic potash gives rise
to a compound, still under investigation, which has strongly marked
fluorescent properties ; the formation of this compound affords a very
delicate test for the mono- and poly-hexoses, and serves to distinguish
them from the pentoses, etc. (loc. cit., 1907, 14, 24).

HOMOLOGUES OK FUKFUKALUEH VDE. 1335

Investigation of the properties and relations of the various com-
pounds here mentioned is now being continued, and in the present
communication a brief account is given of some of the results which
have recently been obtained.

Application of the Friedel and Crafts lieaction.

A mixture of chloromethylfurfuraldehyde (10 grams), anhydrous
aluminium chloride (7 grams), and excess (25 c.c.) of benzene was
heated in a reflux apparatus for about two hours. Reaction began at
about 40° -svith copious evolution of hydrogen chloride, and the tem-
perature was i-egulated so as to keep the liquid in a state of gentle
ebullition. The resulting dark, nearly opaque mixture was then
allowed to cool, poured on to powdered ice, and submitted to .steam
distillation. The first portions of the distillate contained some of the
product of the reaction dissolved in excess of benzene ; afterwards the
main portion of the product passed over as an oil, which, on keeping,
solidified to a crystalline mass. After recrystallisation several times
from a mixture of ether and light petroleum, the product was obtained
in large, colourless prisms, melting without decompo.sition at 30 5^ — 31°»
The total yield was about 6 grams :

0-1229 gave 0-3452 COg and 0-0602 H^O. C = 76-65 ; H = 5-44.

0-1917 ,, 0-5403 CO. „ 0-0926 H.p. C = 7686 ; H =5-37.
CjoHio^a I'equires 0 = 77-41 ; H = 5-37 per cent.

The molecular weight was determined by the cryoscopic method,
using acetic acid and benzene as solvents :

With benzene the results were as follows :

0-2946, in 16-34 benzene, gave A«= -0-495. M.W. = 182.

0-5043 „ 16-34 „ „ A«= -0-875. M.W. = 176.

0-1390 „ 15-18 acetic acid, gave Af= -0-205. M.W. = 174.
C,,H^(,Oo requires M.W. = 186.

The mode of formation and molecular formula of this compound
clearly indicate that it is benzylfurfuraldehyde, the change being
represented thus :

C(CH,C1):CH C(CH,Ph):CH

^<C (CHO)=CH + ^'^' = ^<C(CHO)=:CH "^ ^^^^

Benzylfurfuraldehyde has a faint aromatic odour, somewhat resemb-
ling that of nitrobenzene ; it is almost insoluble in cold water, but
dissolves readily in alcohol, benzene, ether, petroleum, or acetic acid.

The aldehydic character is evidenced by the usual reactions ; it
yields a silver mirror on warming with ammoniacal silver nitrate, and
reduces Fehling's solution only, however, on heating. Its solution in
acetic acid yields with phenylhydrazine a milky precipitate, which

1331) FENTON AND ROBINSON :

settles only to an oil ; if, however, the alcoholic solution is mixed with
phenylhydrazine in slight excess and left in a vacuum desiccator, a
crystalline mass is obtained, which, when wa. hed with ether and
recrystallised from a mixture of alcohol and toluene, melts at
199—204°.

The f)henylhenz}jlhydrazide is more easily obtained ; acetic acid solu-
tions of phenylbenzylhydrazine and benzylf urfuraFdehyde when warmed
together yield, after a time, a white or yellow precipitate, Avhich, after
washing with acetic acid and ether and recrystallising from benzene
and light petroleum, melts at 133° :

0-2440 gave 16-6 c.c. N2 at 15° and 760 mm. N = 8-09.
CggHgoONo requires N = 7"66 per cent.

The oximes of benzylfurfuraldehyde are obtained in a manner
analogous to that employed by Goldschmidt and Zanoli {Ber., 1892, 25,
2573) in the preparation of the oximes of furfux-aldehyde.

A solution of 3*14 grams of sodium hydroxide in 20 c.c. of water
was mixed with 1*1 grams of hydroxylamine hydrochloride in 5 c.c. of
water, and to the well-cooled mixture, 2 grams of benzylfurfuraldehyde,
dissolved in a little ethei-, were gradually added. The resulting
mixture was continuously shaken, and a stream of carbon dioxide was
passed into it, during which process the liquid becomes yellow.
After extraction with ether and evaporation of the ethereal solution,
the pi-oduct separates in pale yellow needles or prisms, which melt at
96 — 97°; these when repeatedly crystallised from light peti-oleum
become colourless and then melt at 99°, This product is practically
insoluble in water, but dissolves easily in organic solvents :

02095 gave 15-7 c.c. N2 at 12° and 757 mm. N = 6-95.
CjgHjjOoN requires N = 6"99 per cent.

By this method of treatment Goldschmidt and Zanoli (loc. cit.)
obtained the anti-aldoxixae of furf uraldehyde ; Fromherz and Meigen,
proceeding in the same way with methylfurfuraldehyde, obtained a
product which was at first considered to be a mixture, but which on
further investigation was shown in all probability to be the anti-
aldoxime. In order to prepare methylfurfuraldehyde sy;i-oxime, the
authors named treated the anti-componnd in ethereal solution with
hydrogen chloride, and decomposed the resulting salt with
sodium hydroxide. The benzylfurfuraldehyde compound obtained in
the manner described above was therefore subjected to a similar treat-
ment ; on passing the gas into the colourless solution, crystals
separated, and the liquid became pale yellow. The ethereal solution on
evaporation deposited a mass of crystals ; these were washed with a
little ether and with water, mixed with excess of aqueous sodium
hydroxide, and warmed for five minutes on a water-bath. The rather

HOMOLOGUES OF FUKFUUALDEHYDE. 1337

yellow liquid so obtained, on cooling, deposited lustrous, silver-
white prisms, which melted at 121 — 122^^ and, after recrystallisation
from light petroleum, at 124° :

0-2245 gave 13-7 c.c. K, at 22° and 755 mm. ]Sr = 7-04.
CjgHjjOgN requires N = 6"99 per cent.

From analogy to the methylfurfui-aldehyde compounds, there appears
to be little doubt therefore that the two compounds here described are
the anti- and syw-oximes respectively of benzylfurfuraldehyde. Both
compounds when dissolved in dry ether, mixed with slight excess of
phenylcarbimide, and kept for twenty-four houi-s, yield crystalline pro-
ducts ; the properties of the derivatives appear also to be different,
but they have not yet been tlioroughly studied.

The properties of benzylfurfuraldehyde are in many other respects
analogous to those of methylfurf uraldehyde ; thus, when concentrated
sulphuric acid is carefully added to a dilute solution of benzylfurfur-
aldehyde in alcohol, a bright blue colour is developed (Maquenne's
reaction for methylfurfuraldehyde gives a green colour). Phloro-
giucinol in presence of concentrated hydrochloric acid gives an orange-
red colour ; I'esorcinol produces a somewhat similar effect, and with
pyrogallol the colour is crimson ; when warmed with carbamide and
hydrochloric acid a violet colour results. Aniline acetate gives a
yellow colour changing to red.

The oxidation of benzylfurfuraldehyde to benzylpyromucic acid has
been attempted in various ways ; the method of oxidation by silver
oxide in presence of sodium carbonate, which was employed by Hill in
the preparation of methylpyromucic acid from methylfurfuraldehyde,
yields a colourless, crystalline acid, which has a penetrating frankin-
cense-like odour. The same product is obtained by oxidation of the
aldehyde with alkaline potassium permanganate at 20°, according to
the method used by Volhard in the preparation of pyromucic acid
[Annalen, 1891, 261, 379); also, by beating the aldehyde with
alcoholic potassium hydroxide, evaporation, extraction with ether, and
acidification of the aqueous solution which remains. In all cases, how-
ever, the yield is extremely poor and the purification difficult. The
partly purified acid melted at 167 — 169°. The authors intend to make
a further study of this acid, when a further supply of material is
available, with the object of obtaining benzylfurane.

It is evident that this synthetical method of preparing substituted
furf uraldehydes may, if desired, be greatly extended, and the authors
propose to make further experiments in this direction.

When toluene and chloromebhylfurfuraldehyde interact in presence
of aluminium chloride, a product is obtained, on steam distillation,
which solidifies to a white solid melting at 74'5°. It is nearly insoluble

VOL. xcv. 4 s

1338 FENTON AND K013INS0N

iu water, but dissolves easily in most organic solvents, and its solutions
show aldohydic properties. From its mode of formation and properties,
this pioduct is presumably tolylmethylfurfuraldehyde,
C(CH,.C,lI,Me):CH
^C(CHO) -CH'

Constitution of Ilydroxymelhylfurfuraldehyde.

It was shown by Dull in 1895 {Chem. Zeit., 19, 216) that inulin when
heated with a solution of oxalic acid under pressure yields hydroxy-
methylfurfuraldehyde as a colourless syrup. This substance was
afterwards more thoroughly examined by Kiermayer {loc. cit., p. 1003),
who obtained it also from sucrose. No positive evidence was forth-
coming to indicate the position of the hydroxy-group, but the author
considered it probable that it occupied the /3-position ; this constitution,

CMe==C-OH
^C(CHO):CH '
has since been universally accepted.

Later it was found by Fenton and Gostling (Trans., 1899, 75, 430)
that bromomethylfurfuraldehyde when treated with the calculated
quantity of silver niti'ate in aqueous-alcoholic solution, or when boiled
with water in presence of barium carbonate, yields a syrup, the
properties of which are closely analogous to those of DuU's hydroxy-
methylfurfuraldehyde. When oxidised with silver oxide, however,
the bromo-derivative and the hydroxy-derivative both yield a hydroxy-
methylpyromucic acid melting at 162 — 163°, which is identical with
that obtained by Hill and Jennings (Amer. Chem. J., 1893, 15,
162) from the bromo-acid, and was shown to be the w-hydroxy-
compound. From this result, and also from the extremely reactive
character of the bromine atom in bromomethylfurfuraldehyde, there
appears to be little doubt that the hydroxymethylfurfuraldehyde
obtained by Fenton and Gostling is also the w-hydroxy-compound, and
it was concluded therefore that it must differ from Dull's product.
This conclusion was supported by the fact that Kiermayer obtained,
by oxidation of the latter product, a hydroxymethylpyromucic acid
melting at 148"^. Further, the phenylhydrazono obtained from this
hydroxyaldehyde was crystalline, melting at 138°, whereas the
corresponding product obtained from Fenton and Gostling's compound
appeared to be a liquid. Further investigation now shows, however,
that the phenylhydrazone from the latter compound is also crystalline,
and that the melting point is the same.

There still remains the fact that the hydroxymethylpyromucic acids
derived from the two products appear to be different, and some further
evidence is therefore desirable in order to clear up the discrepancy,

HOMOLOGUES OF FUIIKUUALDEIIYDE. 13o9

especially since the two modes of Formation of the hyilroxy-uldeliyile
are so closely allied.

The present authors have now obtained a result which ail:ords a
fairly conclusive proof of the correctness cf the formula previously
assigned to chloro- and bromo-methylfurfuraldehyde, and consequently
to the hydroxy-compound which these compounds yield on hydrolysis.
When the chloroderivative is warmed with excess of nitric acid
(D about 1"3), a violent action ensues, and the resulting li(|uid, on
evaporation, yields a white, crystalline mass. This product, which is
free from chlorine, is very sparingly soluble in cold water, but
dissolves easily in boiling water ; it crystallises from the latter in
needles or prisms, which partly sublime when heated, and show no
signs of melting at the boiling point of concentrated sulphuric acid :

0-1005 gave 0-1697 CO, and 0-0258 H^O. C = 46-05 ; H = 2-85.
C^H^Og requires C = 46-15 ; H==2-57 per cent.

The properties of this product agree entirely with those of furan-
2 : 5-dicarboxylic acid (dehydromucic acid) ; ferric chloride, for example,
gives the well-known characteristic reaction ; an aqueous solution of
the acid is mixed with a few drops of the reagent and warmed, when
a transparent jelly separates.

This result then clearly indicates that the halogen must have occu-
pied the <o-position, and is altogether irreconcilable with the formula
suggested for DuU's compound.

The authors consider that, on the whole, the balance of evidence
strongly favours the view that the two hydroxymethylfiu'furaldehydes
mentioned are identical, and that the position commonly assigned to
the hydroxyl group in DuU's compound is incorrect.

Preparation of Chloromethylfurfuraldehyde.

Many attempts have been made to improve on the methods pre-
viously given for the preparation of the halogen derivatives of
methylfurfuraldehyde. Although the yield obtained by these methods
is good, the process of extraction is veiy troublesome when Isevulose or
sucrose is used, owing to the presence of tarry " humus " substances,
and also to the large excess of acid which is necessarily present. The
preparation from cellulose avoids these difficulties to some extent, but
in this case the operation has to be performed under pressure, and is
attended with some danger. Although no substantial improvement
has been effected in the preparation of the products on a fairly large
scale, the following simple process is found to be very rapid and con-
venient when only small quantities are required, since it permits the
use of aqueous acids.

Lievulose is mixed with about twice its weight of solid calcium

4 S 2

1340 LOWRY AND DESCH :

chloride, and the mixiiue is made into a thin paste by stirring it with
concentrated aqueous hydrochloric acid. It is then warmed for a few
minutes on a water-bath with constant stirring, until the whole mass
is dark brown or nearly black, and is suddenly cooled before actual
charring takes place. The excess of acid is then removed by careful
addition of solid sodium carbonate, and the mixture is extracted with
chloroform. On distilling off the chloroform, the chloromethylfurfur-
aldchyde remains as a syrup, which, when well cooled and rubbed with
a rod, often sets to a crystalline mass. In most cases, however, it is
best to purify the product by recrystallisation from hot petroleum, and
to promote crystallisation by contact with a trace of the compound
which has been previously prepared.

The biomo-compound can be prepared in a similar way, using
calcium bromide, or even potassium bromide, and concentrated
aqueous hydrogen bromide.

An attempt to obtain the fluoro-compound in this way, using
potassium hydrogen fluoride and hydrofluoric acid, has not so far been
successful. If calcium chloride and hydrofluoric acid are used, the
chloro-compound only results.

UNIVERSri'Y CUEMICAL LaBOKATOUY,

Cambridge.

CXJ^IX. — Studies of Dynamic Isomeinsm. Part IX.
The Relatio7isliip hetween Ahsoiytio7i Spectra and
Isomeric Change. Absorption Spectra of Sulpho7iio
Derivatives of Camphor.

By Thomas Martin Lowry and Cecil Henry Desch.

In a recent paper on the " Absorption Spectra of the Halogen, Nitro-
and Methyl Derivatives of Camphor" (this vol., p. 807) it was shown
that the isomeric changes which several of these substances undergo
are not directly associated with the presence or absence of bands in
their absorption spectra. Thus, to quote the two most striking cases,
nitrocamphor, which changes readily in neutral and in alkaline solu-
tions, produces an absorption band only under the latter conditions,
but a-bromocamphor, which undergoes isomeric change only in presence
of alkalis, gives a strong absorption band in acid, neutral, and alkaline
solutions indifferently.

The investigation of the isomeric changes of the sulphonic deriva-
tives (Trans, i'jOG, 89, 1042) had presented several points of interest —

STUDIES OF DYNAMIC ISOMERISM. PART IX. 1841

especially in reference to the interaction of tlio carbouyl ^'ronp of the
camphor molecule with the .sulphonic group of the Reychler or /3-si'ries
of compounds — and it was thought desirable to study their absorption
spectra in order to corroborate and extend the conclusions atrived at
from the study of the simpler compounds described in the previous
paper. Observations were therefore made with representatives both
of the TT- and of the /8-series of sulphonic compounds.

In accordance with the scheme de.scribed in the earlier paper, the
absorption spectra were photographed in such a way that each
exposure represented a change of thickness in the ratio 1'2G to 1, an
alteration in the ratio 10 to 1 being thus accomplished by means of
ten equal geometric intervals. This interval, ^^/lO or antilog. O'l,
forms a very convenient unit for measuring the persistence of a band,
and is made use of throughout the present paper.

TT-Sulphonic Derivatives of Camphor.

Three members of the series were examined (Fig. 1) :

(a) Ammonium a-Bromocarnphorir-sulphonate,

OT-fTJr
NH,O.S02-C3H,3<^^ .

— This compound is capable of existing in stereoisomeric a- and
a'-forms, bub does not undergo isomeric change when alkali is added
(Trans., 1906, 89, 1043), probably because the potash merely dis-
places ammonia from the salt, and this base is not sufficiently .strong
to cause enolisation in the 'CHBr-CO' complex. In spite of its
resistance to isomeric change, extending to alkaline as well as to
neutral solutions, the salt shows a strong band persisting over five
exposures in iV^/lOO-solution, as compared with four exposures for the
parent substance, a-bromocamphor.

(b) a-Bromocamphor-TT-sulphonamide, NH2*S02*CsHj3<^ i , is, like

the preceding compound, stable in neutral solutions, but differs from it
in that it undergoes isomeric change to the extent of 15 per cent,
when a trace of sodium ethoxide is added to the alcoholic solution (loc.
cit., p. 1044). The addition of alkali is not necessary, however, for the
development of an absorption band, which appears with a persistence
of four exposures in the neutral alcoholic solutions.

r^HT'r

(c) The acetyl derivative, CH3-CO-NH[-S02-C8Hi3< i , or perhaps

CBr

NH2'S0.2'CsH^3^M , of the preceding compound does not

O'O'LO'UHg

undergo isomeric change either alone or on the addition of a trace of

alkali ; its alcoholic solution shows, however, an absorption band per-

1342 LOWRY AND DESCH :

sisting over five exposures. As its spectrum is almost identical with
that of the amide, it is probable that it is correctly represented by the
former rather than by the latter formula, and that its failure to
undergo isomeric change on the addition of a trace of sodium ethoxide
is due to the elimination of the alkali in the form of sodium acetate,
rather than to the removal of the mobile hydrogen atom by fixing in
the enolic form as shown in the second formula.

pSulp] tonic Acids and tlmr Salts.
The potassium salts, KO'S02'C8Hj3<^ i , of a-bromocamphor-

kjKJ

and a-chlorocamphor-(3-suIphonic acids are stable in neutral solutions,
but undergo stereoisomeric change on the addition of alkali (Trans.,
1906, 89, 1045). The absorption spectra show well marked bands,
but these are actually weakened and not strengthened by the addition
of an excess of alkali. Thus the chlorocamphor band at 1/X 3400,
which has a persistence of four exposures in the parent substance, is
intensified to a persistence of nine exposures by the introduction of
the 'SOg'OK group, but falls back to seven exposures when two
additional equivalents of alkali are added to the iV/100-aqueous
solution (Fig. 2).

CTT

Camphor-^sulplionic acid, HO'S02*CsHj3<^l^^ although unable, in

the absence of an a-substituent, to undergo stereoisomeric change,
behaves otherwise in the same way as the a-chloro-compound. As in
the pi'eceding case, the introduction of the sulphonic group causes an
intensification of the band from a persistence of three exposures in
camphor to six exposures in the /3-sulphonic acid and its sodium salt,
but the addition of two further equivalents of alkali reduces the
persistence again to four exposures only.

A similar repression of the band from eight to six units of persistence
by the addition of two equivalents of alkali was noticed in the case of
A^lOO-aqueous solutions of ammonium a-chloro-7r-sulphonate, and the
phenomenon appears therefore to be a general one in this group of
compounds.

pSulphonamides and Anhydramides.

The amides and anhydramides are the most interesting of the
y8-su1phonic compounds, owing to the evidence which they afford of the
special contiguity of the ^-position to the K-position occupied by the
•CO* group in camphor. The conversion of the amides into anhydr-
amides by the elimination of a molecule of water is not readily
effected by dehyd.rating agents, but is quickly brought about by
acids (Trans., 1902, 81, 1448), or in the case of the parent

STUDIES OF DYNAMIC ISOMERISM. PART IX.

1848

aiilphonamide by rninuto traces of sodium otlioxide (Trans., 1900, 89,
1046). In the case of tlie a-bromo- and a-chloro-sulphonamides the

I CO

SO.,-NHo

CsHj,<

SO,-

CHR

II
-N

n XT ^^GR

I C

HO,-

-NIT

addition of alkali brings about a partial conversion into the stereo-
isomeric a'-compounds, and a similar change of smaller magnitude is
effected in the anhydramides, probably as in other instances, throiigh
the intervention of an " enolic " (sulpholactam) isomeride as
formulated above. In contrast to the mono-halogen derivatives, the
anhydramides of the aa'-dichloro- and dibromo-sulphonic acids can

Fig. 1.

Va = 3000 34
3-8

Fig. 1. — a-Bromocam2}hor,ammoimi,ma-hromocamplwr-ir-sulpJionate, and a-hromo-
camphor-Tr-sulplionamidc ; N/100 solutions in alcohol.

Fig. 2. — a-ChlorocampJior and potassixim a-chIoroca7npJio7'-0-sulpJionafe in neutral
solution and with 2 equivalents of sodium hydroxide : N/100 solutions in tvater.

Fig. 3. — Camphor- 0-anhydra7)iide and the 0-sulpho7iamides of camphor, a-methyl-
camphor, and a-chlorocamphor ; N/100 solutions in alcohol.

only exist in one form, and do not undergo isomeric change whether
alone or in presence of alkali.

The spectra of this series of compounds proved to be of special
interest owing to the steady disappearance of the power to produce
absorption bands on passing from bromo- to chloro- and to metliyl
derivatives, and finally to derivatives of camphor itself (Fig. 3). This
is well brought out in the following table.

Methyl- Chloro- Bromo-

Camphor. camphor. camphor. camphor.

Band Band Band Band

No band No band ,, ,,

Salts

Amides

Anhj'dramides .
Disubstituted
anhydramides

No band

No Ijand

C8Hi3<T^^

1344- LOWRY AND DESCH :

From this t<able it appears that the absorption band which is
developed by all the salts and by the sulphonamides of a-chloro- and
a-bromo-camphor can be eliminated quite as effectively by displacing the
halogen atom of the sulphonamides by methyl or by hydrogen, as by
the more usual process of displacing the remaining hydrogen by a
second halogen atom. In the case of the amides the disappearance of
the absorption band might be attributed to an internal condensation
of the sulphonamide, which would give rise to a completely saturated
molecule :

SO,, NH

This explanation cannot, however, be given in the case of the
anhydramides, which must all be formulated as :

ri XT ^CHR p, -rr ^CR

i C or I C .

I II II
SO., N SO2 NH

Of the six anhydramides examined, the diehloro- and dibromo-
compounds on the one hand and the camphoranhydramide on the
other show no band; of the mono-substituted anhydramides the a-bi'omo-
compound gives a band, but the a-chloro- and a-methyl compounds
give rise only to general absorption.

These observations appear to indicate that the development of a band
is influenced to a very large extent by substitution, but in a way that
bears no direct i^elationship to the occurrence or even to the theoretical
possibility of isomeric change.

Anilides of (i-Sulphonic Acids.

The anilides of this series possess the curious property of dissolving
in alkalis, possibly owing to the formation of a ring compound, for
example :

p „ ^OHBr ., „ .CHBr

I CO — > I C-ONa .

SOa'NH-CeHs SO^ N'C,.Hj

The absorption curves for the alkaline solutions are characterised
by the presence of a band in the far ultra-violet at 1 IX 4000. This
band, which was observed in the case of camphor-^-sulphonanilide,
camphor-^-sulpho-^-bromoanilide, a-bromocamphor-/3-sulphonanilide,
and a-bromocamphor-/3-sulpho-;?-bromoanilide, is of great intensity,
persisting to a thickness of a few millimetres only of iV/10,000 solution,
but does not appear in the neuti-al solutions, which are one hundred

1

STUDIES OF DYNAMIC ISOMERISM. PART IX.

1345

times less absorbent. It re.semblos somewhat closely one of the bands
noted by Baly and Collie (Trans., 1905, 87, 1342) in the spectrum of
dimethylaniline, and is identical in position with a band which they
observed (at a thickness of solution 400 times greater) in the spectrum
of aniline hydrochloride. It will probably be correct to refer this band

Fig. 4.

Va =3000 32 3-1 3G 38 4000 42 44
3-4

3-2
3-0

2'8
2-6
2-4
2-2
2 0
1-8
1-6
1-4
1-2

ro

0-8
0-6
0-4
0-2
0-0
1-8
1-6
1-4

^

N,

\

\

\

\

5 -Art.

tu^

v

/

\

\

^

/

\

\

\

<.

\

\

^

\

\

\

\

\

\

(« r

K:

\

\ /S .

3'»

\

~..

V

ll

s

s

i

\

2000
1000

500

300

200

100

50

o

r-H

30

12;

20

■^

0-5
0-3

Fig. 4. — (1) Camphor-Q-sulphnnanilidc in neutral N/100
solution and (2) in N/10,000 solution with N/1000 NaOEt.
(3) a-Bromocnmphor-B-f!idpho-])-hromoanilide in N/10,000
solution with N/1000 NaOEt.

to the IN'CgHg group, although it is not easy to say to what its
exceptional intensity is due.

The neutral solutions, which give complete transmission at a
concentration of i\7100, are also characterised by the presence
of absorption bands. Thus a neutral solution of camphor-
)8-sulphonanilide,

( > H n

shows a band at 1/A, 3700 at a thickness of 3 mm. of iV/lOO solution,

1346 RTITDTES OF DYNAMIC ISOMERISM. PART IX.

that is, at a concentration !()() times greater than that at wliich a
band appears in presence of alkalis ; we are at present unable to offer
any opinion as to its significance.

Piperidides of ^-Sulphonic Acids.

Camphor-yS-sulphonic acid is characterised by the formation of two
isomeric piperidides melting at 56° and at 140°, which have been
formulated as :

I CO and I 0-2SrC,H,o.

SOg-NCsHjo iSOa 0

The a-bromo-compound also exists in two distinct forms melting at
75° and 123°, each of which exhiljits a change of solubility on the
addition of alkali, and must therefore be capable of undergoing
reversible isomeric change (Trans., 1906, 89, 1051). These isomeric
compounds are not easy to prepare,* and up to the present we have ex-
amined only the absorption spectra of the camphorsulphopiperidide
(piperidolactone) melting at 140° and the bromocamphorsulpho-
piperidide melting at 75°. The former compound shows no selective
absorption, but the latter compound gives the bromocamphor band at
1/A. 3350 with a persistence of four exposures. These observations are
in accord with the formuke that have been assigned to the two
compounds, but in view of the somewhat slender evidence on which
these formulre are based, we do not feel justified in drawing any
theoretical deductions from the presence or absence of bands in the
spectra.

We are indebted to the Research Fund of the Chemical Society for
a grant which defrayed a portion of the cost of this investigation, and
desire to take this opportunity of expressing our thanks.

130, HORSEFERRY RoAD, ThE UNIVERSITY,

"Westminster. Gt<asgow.

* The camphorsiTlphopiperidide of lower melting point can bo obtained in a crys-
talline form by slow evaporation of the solvent, but as it liquefies again on the
addition of alcohol or petroleum, it is very difficult to purify. Attempts to prepare
further quantities of the bromojiiperidides liave given rise to a new product melting
at 86°, the nature of which is under investigation.

STUDIES OF THE OARRONATES. PART T. 1 fi47

CL. — Studies of the Carhonates. Part I. Tlie Equi-

lihriiLyn hctinren Calcium Carbonate and Ca7^J)onic

Acid.

By Clarence Arthur Seyler and Percy Vivian Lloyd.

The object of this investigation was to study the equilibrium between
calcium carbonate and cai'bonic acid under conditions applicable to
,i,'eological problems. Schlossing's results have been examined by
liodUinder (Zeitsch. physikal. Chem., 1900, 35, 32), who has shown how
the law observed by SchliJssing may be deduced from first principles.
Natural waters, however, contain salts which modify the equilibrium,
and we have therefore studied their effect.

Method of Experiment.

The solid carbonate, reduced to a coarse powder, was kept with
occasional shaking in contact with the solution of carbonic acid and
the various salts contained in stoppered bottles completely filled. The
temperature was that of the laboratory. Several weeks were required
for the attainment of equilibrium. The dissolved carbonate was then
titrated with iV/20-acid, using methyl-orange as indicator, and the
free carbonic acid determined by titration with i^/^O-sodium carbonate
and phenolphthalein as indicator, using the precautions described by
Seyler {Analyst, 1897, 22, 312). This method is rapid, and has
been shown by Ellms and Beneker (./. Amer. Chem. Soc, 1901, 23,
405) to be more accurate than the original Pettenkofer method or
Trillich's modification of it, and to be trustworthy to about 0"02 x lO"''
gram-molecule per litre. This mode of experiment has the advantage
over Schlossing's, in which a current of carbon dioxide of known
partial pressui'e is used, since the carbonic acid is directly determined,
and the temperature does not require to be kept more than approxi-
mately constant.

liquations Governing Equilibrium in Absence of Salts.

We use Bodlander's symbols as follows :

HCO3, Ca, etc., in equilibrium equations stand for the concentration
of the respective substances in gram-molecules or ions per litre.

^2 is the dissociation constant of carbonic acid according to the
scheme HgCO^ - H 4- CO3.

^3 is the dissociation constant of bicarbonates according to the
scheme HCO3 ^^ + ^^r

1348 SEYLER AND LLOYD :

A-j is tho J " solubility product " of calcium carbonate, namely,

A-, = Ca-COg.

k,i, is tbe dissociation constant of water.

k .
The ratio ^ jg the dissociation constant of l)icarbonates into

carbonates and free carbonic acid according to the scheme 2HC03 =
CO, + H,C03.

The condition of equilibrium for this is :
HC0 2 k.

"2

H2C03-003 /fcg
Since Gn'CO^^k^, we have :

(a).

H2CO3 k^
This is the fundamental equation. If no other lime salts or
bicarbonates be present except those due to the dissolved limestone,
practically the whole of the calcium will exist in solution as bicar-
bonate, since CO3 is always very small. The concentration of the
calcium ions (Ca) will always be half that of the bicarbanions
(HCO3), since there are two of the latter for each one of calcium.

Hence we have the concentrations Ca = ^.

2

Therefore .substituting in equation (b) we have :

This is Schlcissing's law as deduced by Bodliinder. The values of

k.
the constants -^ and k■^ are open to discussion, and for the present we

k
shall put 2-^kj = Fx 10"°, where i^ should be constant. We call it the

h
" saturation factor," since it is a criterion as to whether a water is
saturated with limestone or not. We have calculated its value from
Schlos-sing's experiments in which the temperature was 16°, corre-
sponding with a molecular solubility of carbonic acid of 435 x 10"^
gram-molecules per litre. It decreases from about 137 for Nj60- to
about 107 for iV/600-solutions (with respect to calcium), the mean
being 124.

Experiments were first made on marble and pure limestone with
solutions of carbonic acid in order to test our method of working, and
the results are given in table I.

STUDIES OF THE CARBONATES. PART I.

1349

Table I.

Solid.
Marble

Time
(day.s).
4:3
75
44
29

H0CO3 X 10-'.

2-687

3-62

10-00

11-40

2Ca X 10^'

7-41

8-29
12-08
13-14

loiiisatiou.
0-88
0-88
0-87
0-86

IICO;, X 10\

6-52

7-29
10-51
11-30

F.
1031

107-0

Limestone ....
Marble

1161
126-5

The average value of F in 113, and the results show a decrease in
dilute solutions, as in Schlossing's experiments.

Effect of Other Calcium Salts.

The general equation {b) should hold good, Ca being the total
concentration of the calcium ions. We shall have :
HC03-2Ca^^^j^_,_

H,C03

the

The presence of other calcium salts will therefore diminish
solvent action of water containing carbonic acid upon limestone.

Calcium Chloride. — The solution of this salt was ^/80, that is, it
contained 12-5 x 10"^ gram-equivalents per litre. The degree of
dissociation of calcium bicarbonate is assumed to be the same as that
of calcium chloride.

Table II.

Calcium as Calcium

bicarbonate as

Time. H2CO3X10-'. xltfi. lonisalion. HCO3XIO3. cbloride. loiiisatiou.
12 3-95 6-13 0-845 5-18 12-5 0-845

Total

calcium,

Ions. :.'Ca. F.

10-56 15-74 107

Calcium Sulphate. — The concentration of this salt was from
2-382 X 10~^ corresponding with about 84 degrees of permanent
hardness on Clai'k's scale, to 12-5 x 10~^, or 44 degrees of hardness.
The degree of dissociation was calculated approximately by dividing
the water between the bicarbonate and sulphate in such proportions as
to give isohydric solutions, and finding the degree of dissociation
which each would have if dissolved in its respective volume of water.*

* An examijle will make clear the method of calculating the degree of ionisation
in the case ol mixtures. Let the solution contain 2-38 mg. equivalents of calcium
sulphate and 6-33 of calcium bicarbonate. The ionisation was calculated from the
conductivity as given in Landolt-Borustein's tables, 3rd Ed., the ionisation of the
bicarbonate being assumed to be the same as that of calcium chloride. Divide the
water by trial between the two salts so that the solutions are approximately iso-
hydric. Thus, 2-38 mg. equivalents of sulphate in 210 c.c. of water give a con-
centration of 11-33 mg. equivalents per litre, corresponding with ionisation of 0-622
and concentration of calcium ions 7-05 mg. equivalents per litre. The 6-33 mg.
equivalents of bicarbonate dissolved in the rest of the water (790 c.c.) give a con-
centration of 8 01 mg. equivalents per litre, corresponding with ionisation 0-89 and

1350 SEYLER AND LLOYD:

Table

III.

Calcium

Total

loiiis-

as

calcium,

Time.

U2CO:;.

(Oa/2HC03).

atioii.

llCOy.

C:iS04.

lonisatiou.

suliihatc.

•JCa.

F.

43

l-O-l

4-89

0-91

4-45

2-382

0-612

1-53

5-98

114

16

1-81

6-08

0-895

5-41

2-382

0-630

1-50

6-94

113

43

2-06

6-33

0-89

5-63

2-382

0-6'22

1-48

7-11

109

16

3-15

7-25

0-88

6-38

2-382

0-60

1-43

7-81

101

43

4-55

8-83

0-88

7-77

2-382

0-59

1-40

9-17

121

16

6-56

9-85

0-872

8-59

2-382

0-585

1-39

9-98

112

—

3-562

7 '00

0-875

6 12

6 -25

0-579

3-62

9-74

102

— 4-94 7-58 0-897 6-80 12-50 0-545 6-81 13-61 127

The average value of F is 113, the same as in the absence of
extraneous calcium salts.

Effect of Sodium Bicarho^iate. — The same general law should hold
good, but the solubility of the limestone should be reduced in a still
greater measure, namely, inversely as the square of the total
bicarbonate when the free carbonic acid is kept constant. The degree
of dissociation of the sodium bicarbonate was assumed to be the same
as that of calcium bicarbonate.

Table IV.

ncoj HCO3

lonis- as as Total

Time. U.2CO3. (Ca/J-HCOs). ation. calcium. NallCOy. luiiisation. sodium. HCO3. F.

54 4-75 5-57 0-S69 4-84 6-25 0-869 5-43 10-27 107

54 4-06 3-40 0-850 2-89 12-50 0-«5 10-62 13-51 130

Effect of Salts Containing no Common Ion loith Calcium Bicarbonate.

The effect of sodium chloride, sodium sulphate, and magnesium
sulphate was examined. These salts should somewhat increase the
value of F, that is, the solvent action on calcium carbonate. This
was found to be the case.

Table V

lonis-

Salt. Time. H.2CO3. {Ca/2*HC03). ation. HCO3. F.

NaCl: 12-5x10-^ 54 3-10 8-25 " 0-89 7-34 127

Na2S04: 12-5 x IQ-^ 54 1-875 7-32 0-90 6-59 152

Mg.SO^: 6-25x10-^ 53 4-44 9-22 0-885 8-16 122

MgS04: 6-^5x10-^ 53 256 8-12 0-89 7-23 147

For ordinary fresh waters the effect of these salts on F is
slight, but in mineral waters or sea- water ib would have to be
considered.

Value of the Constants. — The value of k-^, the " solubility product "

concentration of calcium iou.s 7-13 mg. equivalents per litre. The solution.s are
therefore approximately isohydric, and the degree of ioni.sation will not alter on
mixing Therefore, the ionisatiou of the sulphate iji the original solution in 0-622,
and of the bicarbonate, 0-S9.

STUDIES OK THE CARBONATES. I'AllT I. 1351

of calcium carbonate, could be calculated if ^12/^3 were known. Jc.^ is
known to bo 3'04 x 10"^ from the expoiimonts of Walker and
McCormack. Bodliinder has calculated k^ from the experiments of
Shields on the hydrolysis of sodium carbonate, but McCoy {Amer.
C/iem., J., 1903, 29, 437) has pointed out that some error has crept into
the calculations of Shields, so that Bodlander's value for k.^, and hence
for k^, is wrong. IVfcCoy [loc. cit.) determined the value of k.JIc,
directly. It increases very considerably on dilution, and was found to
be 5300 for iV/10-solutions. McCoy assumes that it would become
constant beyond this dilution, but we have found that this is not the
case. We have extended McCoy's determinations to higher dilutions,
and also repeated and amplified Shields' experiments, and prefer to
leave the discussion of the value of k^ until the publication of tliese
results. In any case, the value of F should be proportional to k^ for
different forms of calcium carbonate, and should also be a function of
the solubility of the carbonate in pure water. The " solubility
product " cannot be inferred from the latter unless the degree of
hydrolysis is known.

Since A;^ = Ca x CO3, we should, supposing no hydrolysis, have
Ca = CO3 and ^^ = Ca^, where Ca is the concentration of the calcium in
a saturated solution of the carbonate in pure water. J>ut calcium
carbonate is undoubtedly hydrolysed to a largo extent according to
the scheme: CaC03 + 2H20-Ca(HC03)o + Ca(OH),. Here the con-
centration of the bicarbonate is equal to that of tiie hydrate, and we
have the concentrations :

or Ca = C03 + HC03.

If the percentage of hydrolysis be lOOx, then HCOg^suCa and
CO3 = (1 - a;)Ca, so that k^ = Ca x CO3 = { 1 - ;f)Ca2. l^r different
forms of calcium carbonate, say calcite and aragonite, a; will be
practically the same, since the solubilities are not widely different.

Let k^, Ca, and F apply to calcite, and ^j', Ca', and F' to aragonite,

then :

F k; Ca'2 Ca' fF'

- = -1 = or - — / - .

F k^ Ca^ Ca V f"

Whatever the actual value of k-^ or of the hydrolysis, the square
roots of F should be proportional to the solubilities of the two forms.
We have tested this conclusion by experiments on calcite and aragonite
under identical conditions.

Table VI.

lonis-
Substance. Time. H.^COa. (Ca/2-HC03). alioii. HCO,. F.

Calcite 173 l"605 6-37 0-91 5-79ti 121-3

Aiafrouite 173 1-145 6-29 0-91 5-723 lti3-7

1852 STUDIES OF THE CARBONATES. PART I.

The ratio , is r35, and the sijuaie root, ri62. According to

Kohlrausch, the relative solubilities of aragonite and calcite are at
18° as 15 to 13, and the ratio, 1'154. The agreement is satisfactory.
Evidently aragonite, being the more soluble form, must gradually pass
into calcite if both forms are present.

Conclusions.

(1) The equilibrium between calcium carbonate and fresh waters is
governed by the law :

HCO 2 X Ca

H2CO3

/'xlO-G,

where ^ is a constant.

(2) The mean value of /'' is about 113 for calcite. It is a critei-ion of
the saturation of a water in contact with limestone, and may be called
the "saturation factor" of the water. If less than 113, the water is
not saturated, if over 113 it is supersaturated.

(3) This law has been verified in the presence of calcium chloride,
calcium sulphate, sodium bicarbonate, sodium chloride, sodium sulphate,
and magnesium sulphate in quantities such as occur in natural fresh
waters. For mineral or sea-waters the factor would be increased.

(4) The law may be stated in familiar terms as follows, the hard-
ness referred to being that produced by lime salts, and correction for
ionisation being supposed. In general, when a water is in equilibrium
with the limestone through which it percolates :

(a) The square of the alkalinity is directly as the free cax'bonic acid
and inversely as the total hardness.

If there is no alkalinity or hardness except that due to the
dissolved limestone, then :

(b) The cube of the temporary hardness (dissolved limestone) is
directly as the free carbonic acid.

If permanent hardness (due to lime) is present, then :

(c) The square of the temporary hardness (dissolved limestone) is
directly as the free carbonic acid and inversely as the total hardness.

If permanent hardness is absent and other bicarbonates are present,
then :

{d) The hardness (dissolved limestone) is directly as the free
carbonic acid and inversely as the square of the alkalinity.

(5) The constant F is proportional to the " solubility product" of
the solid calcium carbonate, and to the square of the solubility in pure
water in the case of calcite and aragonite.

rt'jBLic Analyst's OrriOK,
Swansea.

DOUBLE AND TRIPLE I-EIIROCYANIDES. 1353

CLI. — Double and Trij^le Feyrocyanides of Macjnesium,
Aluminium, and Cerium with Potassium and
Ammonium.

By Fredkric William Robinson.

The object of this work was to ascertain which metals form double
ferrocyanides with potassium, the nature, composition, and properties
of these salts, and the effect of the presence of ammonium salts on
their formation and composition. Further, in the case of triple salts,
to determine whether they are definite salts, or whether the composition
varies with the conditions uiider which they are prepared.

It has already been shown that, in the case of the double ferro-
cyanides of calcium, the presence of ammonium salts causes the
precipitated salts to contain ammonium, but not in definite quantity
(Campbell Brown, Trans., 1907, 91, 1826), and the metals strontium
and barium (Campbell Brown, loc. cit.), zinc and cadmium (Miller,
J. Amer. Chem. Soc, 1902, 24, 226, 823; 1904, 26, 952), and
thallium (T. Fischer and Benzian, Chem. Zeit., 1902, 26, 49) have
also been previously investigated.

Preparation of Potassiuvi Magnesium Ferrocyanide.

Equivalent quantities of cold concentrated solutions of potassium
ferrocyanide and magnesium chloride were mixed. After a short time
a white, microcrystalline precipitate was formed, which was collected,
washed with cold water, and dried in a desiccator. Under the micro-
scope the crystals were seen to consist of square plates, and these
were not altered by drying or by heating to 120°.

The air-dried salt, after being heated for five hours at 105*^, and
then at 120° for two hours, lost no weight. The salt as precipitated
is therefore anhydrous. When pure it is white, but, unless quite dry,
soon becomes cream-coloured, owing, probably, to the action of
atmospheric carbon dioxide. Cigli, in 1898 {Chem. Zeit., *2,Q,, 868),
showed that carbon dioxide decomposes aqueous solutions of ferro-
cyanides.

Solubility. — A saturated aqueous solution of the salt contains
1'95 grams per litre at 17°.

Analysis. — The method of analysis adopted was the same as that
employed by Campbell Brown for the analysis of potassium calcium
ferrocyanide {loc. cit.), namely, by treatment with lead chloride and
estimating the magnesium and potassium in the filtrate from the lead
ferrocyanide :

VOL. XCV. 4 T

1854. ROBINSON : DOUBLE AND TRIPLE FERROCYANIDES OF

Found, Mg = 7-72; K = 24-45.

KoMgFeCgN,. requires Mg = 7-64 ; K = 24-84 per cent.

Preparation of Ammonium Magnesium Fen'ocyanide.

Ammonium ferrocyanide was mixed with a concentrated solution of
magnesium chloride in equivalent proportion. Small, white crystals
were obtained, having the same form as the potassium salt. The salt
lost no water at 105° or 120°.

Soluhility. — A saturated aqueous solution of the salt contains
2-48 grams per litre at 17°.

Analysis gave the following results :

Found, Mg = 8-68; NH4= 13-06.
(NH4)2MgFeC6Ng requires Mg = 8-92; NH4= 13-20 per cent.

Preparation of Triple Salts under Varying Conditions.

Precipitates were formed by mixing potassium ferrocyanide,
magnesium chloride, and ammonium chloride in the proportions shown
in the accompanying table.

The precipitated salt was in each case collected, washed with cold
water, acetone, and ether, and kept in a desiccator.

The percentages of ammonium in these salts were determined. It
was found that the proportion of ammonium to potassium in the
precipitate varies with the amount of ammonium chloride present at
the time of precipitation, but is not in the simple ratio of NH^ : K in
the solution. When the proportion NH^ : K in the solution is less
than about 1-7:1, the pi'oportion NH^ : K in the precipitate is less
than in the solution, but as this ratio approaches 2:1, the proportion
of ammonium in the precipitate becomes greater than in the
solution.

Table Showing Influence of Varying Proportions of Ammonium and
Potassium on Composition of Salts.

Ratio Percentage Percentage

NH, :K NH4:NH4 + KNH4:NH, + K

Mols.

Mols.

]\Iols.

in initial

in

in initial

Salt.

MgClo.

K^FeC^Nfi.

NH4CI.

solution.

precipitate.

solution.

A

1

1 : 4

13-9

20-0

B

2

1 :2

25-4

33-3

C

4

1 :1

45-3

50-0

D

8

2 :1

68-1

66-6

E

20

5:1

86-2

83-3

F

2

20

r> : 1

87-0

83-3

G

1

G-8

1-7 : 1

63 1

63-0

MAGNESIUM, ALUMINIUM, AND CERIUM. 1355

As tlio time of precipitation might influence the composition of tlio
precipitate, the salt C was collected fractionally. The solutions of
potassium ferrocyanide and ammonium chloride were well mixed, and
the magnesium chloride solution then added, the mixture being
quickly stirred and kept for fifteen minutes. The precipitate was
collected, and the filtrate kept for an hour, when the bulk of the
precipitate had formed. After collecting this, the solution was kept
overnight, when a further quantity of salt was precipitated. The
fractions were called C^, Cj, and C3.

As it was possible that these fractions were not ecjually soluble in
water, they were washed with a mixture of eijual parts of acetone and
water, then with pure acetone, and finally with ether.*

The ammonium in these fractions was estimated, with the following
results :

Cp NH^ = 4-63, equal to 38-9 per cent, of (NH4)2MgFeCgN,;.

C, NH, = 4-65, „ 39-1

C3, NH, = 4-83, „ 40-6

When a large excess of ammonium chloride is present in the
solution from which the salt is precipitated, ammonium begins to
displace magnesium before it has displaced all the potassium. The salt
E gave Mg = 8'65, NH^ = 11-41, and K = 3"47 per cent., corresponding
with 46-8 per cent, of Mg^FeC^jNy, 45-0 per cent, of (NH4)4FeCyN^,
and 8-2 per cent, of K^FeC^N,..

Salt F, prepared from the same proportions of ammonium chloride
and potassium ferrocyanide, but with one-half the proportion of
magnesium chloride as compared with E, gave Mg= 860, NH4= 11*52,
and K = 3'34 per cent., corresponding with 46*5 per cent, of
Mg^FeCgNg, 45-4 per cent, of (NHJ^FeCgNg, and 8-1 per cent, of
K^FeC.N,.

Aluminium Sails.

Wyrouboff {Ann. Chim. Phys., 1879, [v], 18, 446) described the
preparation of aluminium ferrocyanide by mixing cold concentrated
solutions of potassium ferrocyanide and alum, to which he assigned
the formula Al4(FeC^N6)3,17H20.

In order that the salt may be precipitated in a filterable form, it is
necessary that a large quantity of electrolyte be present ; the
probability is that Wyrouboff prepared the salt in presence of excess
of alum. Had he not done so he • would have obtained a double salt,
KAlFeCyN^^.xHgO, similar to the double salts which have been
investigated by the present author.

* These salts are iiisohible in a mixture of acetone and water, and in the time
taken to filter olF, the mixture does not [ireci[)itato any salts from the mother li(|uur,
althouf^'h it does so after some minutes.

4 T 2

135G ROBINSON : DOUBLE AND TRIPLE FERROCYANIDES OF

Preparation of Potassmm Aluminium Ferrocyanide.

^V/2-Aqueoas solutions of pure alumiuium chloride and potassium
ferrocyanide were mixed in molecular proportions, and, on keeping, the
whole set to a stiff jelly. The preparation was therefore repeated,
using Nji- and X/S-soIutions, and in each case a similar result was
obtained ; the jelly did not settle, and passed easily through a filter
paper. Other methods of precipitation were therefore tried. The
double ammonium salt prepared in the same way was found to be a
similar jelly. With the aid of a microscope, it was just possible to
perceive the granular nature of the jelly.

The action of coagulants on the jelly was tried, but heat had no
effect on it, and alcohol, acetone,' ether, or other organic liquids did not
flocculate it even on boiling.

The 6-alts were also precipitated in presence of ions of high valency,
alike positive and negative, but flocculation was not effected with either
platinum tetrachloride or ammonium hydrogen phosphate.

When the potassium salt was prepared in presence of a large
quantity of potassium chloride, it settled on standing, and could be
filtered off by the aid of a pump. As, however, it was desirable to
isolate the salts precipitated in presence of an amount of potassium
or ammonium equivalent only to that requii^ed for the formation of
the salt KAlFeC^;Ng, other methods were tried, and finally two were
successfully employed.

Method I. — By means of a porous porcelain fl.ask immersed in the
jelly, the inside of the flask being connected to a filter pump, the salt
could be slowly filtered off, and washed successively with water, alcohol,
and ether. The dried salts are dark green in transparent masses, and
when powdered are light bluish-green.

Method II. — The jelly was centrifugated at 3000 revolutions per
minute, when the precipitate collected at the bottom of the tubes,
leaving a clear liquid above, but the precipitate on suspension in
distilled water did not settle again when centrifugated, so that
it was impossible to wash the salt with water. It was therefore
centrifugated after suspension in iV-aqueous potassium thiocyanate,
from which it readily settled, and again after suspension in
acetone.*

Potassium thiocyanate is soluble in acetone, and the solution
does not decompofee the salt. After centrifugatiug with acetone,
the salt was collected, washed with acetone and then ether, and dried
in a vacuum.

* The suspension of the jelly in acetone is effected liy rubbing in a mortar, but is
a rather tedious operation.

MAGNESIUM, ALUMINIUM, AND CERIUM. 1857

Analysis. — A kuown weiglit of tho salt was fused witli potassium
hydrogen sulphate, and the coolod product was dissolved in water,
oxidised by nitric acid, and the mixed hydroxides of iron and aluminium
precipitated by ammonia, calcined, and weighed. Iron was estimated
volumetrically in the product of a separate fusion.

Analysis shows that the potassuim salts isolated by contrifugation
(I) and filtration (II) possess the same composition :

Found, (I) Fe = 15-36 ;A1 = 7-95.
(II)Fe = 15-5; Al = 7-97.
KAlFeC,.N^,4HoO requires Fe= 16-0 ; Al = 7-72 per cent.

As indicated, the salts contain 4 molecules of water; this is lost at
100°.

The ammonium aluminium salt was also analysed :

Found, NH4 = 5-22.

NH^AlFeC,.N^,,4H20 requires NH4 = 5-47 per cent.

These salts therefore possess the composition : RAlFeC,;Ng,4H20,
where R is the alkali metal.

When anhydrous they have a deep blue colour, resembling that of
Prussian -blue.

As the salts prepared in the presence of a large quantity of
electrolyte could be readily filtered, the double salts were prepared by
mixing concentrated solutions containing the molecular proportions of
potassium ferrocyanide, aluminium chloride, and ammonium chloride
indicated below, and the precipitates were washed with a mixture of
equal parts of acetone and water, then with acetone, and finally with

ether.

Salt. K^FeQjNu. AlCl,. NH4CI. KCl.

A 1 1 — 20

B 114 —

G 1 1 12 —

In the case of the potassium salt A, pi'epaved in the presence of a
large excess of potassium chloride, it was found that some of the
aluminium had been displaced by potassium, the amount of aluminium
found being only 6 '20 per cent., approaching the value for

(K2Al),(FeC,N«)5,20H2O,
which requires Al = 5'8 per cent.

The triple salts, or mixed double salts, exhibit very similar
phenomena to those observed in the case of the cori'osponding mag-
nesium salts, as is shown by the following table.

Percentage Percentage

NH4:Kin NH4 : NH^-}- K in NH, :NHj+K
Salt. initial sohition. initial solution. in salt.

B 1:1 50 47-5

G 3:1 75 70 4

1358 ROHTNROX: DOUP.LE AND TRIPLE FERROCYANIDES OF

Tlioso results point, to the fact tliat, as in tho case of magnesium,
the ammonium double salt is more soluble in water than that of
potassium.

Thallium.

Attempts were made to prepare a double ferrocyanide of thallium
and potassium of the formula KgTlFeCcNg, but without success, the
salt Tl^FeC^N(5,2H20 always resulting. This salt was first prepared
by Kuhlmann (Compt. rend., 1862, 55, 607), who found that it was
soluble in excess of potassium ferrocyanide, but he did not analyse it.

Lamy and Descloizeaux {Compt. rend., 1868, 66, 1146) prepared the
same salt, and assigned to it the formula Tl2FeC3N3,2HO. They found
that it loses water at 100°. The salt has been found to crystallise in
well-defined, yellow, quadratic pyramids, sparingly soluble in cold, but
readily so in hot, water. It is stable in' air, but loses its water of
crystallisation on keeping over calcium chloride. A cold saturated
.solution of this salt in a i\Y2-solution of potassium ferrocyanide was
prepared and allowed to evaporate isothermally over sulphuric acid,
when only the original salt, Tl4FeCgNf.,2H20, was deposited.

Fischer and Benzian (loc. cit.) have also tried without success to
prepare this double salt, but obtained one of the composition
K4FeCcN^„K3TlFeCcNo,6H20.

Cerium.
Preparation of Potassium Cerium Ferrocyanide.

Equivalent quantities of cold concentrated solutions of potassium
ferrocyanide and pure cerium chloride (Kahlbaum's) were mixed, when
a white salt was precipitated. This was collected, washed with water,
and dried in the air. Under the microscope it appeared to be crystal-
line, but the shape of the crystals could not be determined.

When heated at 100° and finally at 120°, the salt lost no weight,
and is therefore anhydrous.

A'ludysis. — A known weight of the cerium salt was fused with
potassium hydrogen sulphate, the mass being then cooled and extracted
with dilute hydrochloric acid. A small quantity of nitric acid was
then added to oxidise ferrous salts, and, after cooling, the solution was
rendered nearly neutral with ammonia and the cerium precipitated as
oxalate by ammonium oxalate. The precipitate was collected, dried,
ignited, and weighed as CeOg :

Found, Ce = 35-6.

KCeFeCgNg requires Ce — 35*8 per cent.

The salt is therefore analogous to the potassium aluminium ferro-
cy.anide already described.

t

MAGNESIUM, ALUMINIUM, AND CERIUM. 1359

Sodium and aramoninm cerium ferrocyanides were a\HO prepared, and
were found to possess compositions analogous to that of the potassium
cerium salt.

Sodium cerium ferrocTjanide : Found, Ce — .36*9.

NaCeFeC^,N,. requires Ce = 37*3 per cent.
Ammonium ceriuvi Jerrocyanide '. Found, Ce = 38'4.

NH^CeFeCgN^ requires Ce = 37-9 percent.

Influence of the Presence of Ammonium Chloride on the Composition of
the Precipitated Salt.

Precipitates were formed by mixing potassium ferrocyanide, cerium
chloride, and ammonium chloride in the px'oportions shown in the
accompanying table. The pi-ecipitated salt was in each case washed
with a mixture of acetone and water, then with acetone, and finally
with ether, and was kept in a desiccator.

The percentages of ammonium in these salts were determined, and
were found to vary with the proportion NH^ : K in the original solu-
tion, but were not strictly proportional to it.

NII4 : K Percentage Pcrcentaife

ratio NH4 : NH.^ + K Nn4 : NH4 + K

Mols. Mols. Mols. in initial in in initial

Salt, CeCl^. KjFeCjjNfi. NH4CI. solution. precipitate. solution.

A 1 1 2 1:2 25-54 33-3

n 1 1 4 1:1 41-82 50-0

C 1 1 8 2:1 56-24 66-6

D 1 10 10 1:4 14-48 20-0

When the proportion of cerium to the alkali metals is small, as in
the salts C and D, the same behaviour is observed as with magnesium
and aluminium, namely, that the cerium is displaced by the alkali
metals, tending to form the salt (R2Ce)4(FeC(.Ng)5, R being the alkali
metal :

Salt C contains Ce = 33-2, and Salt J), Ce = 29-6.

KCeFeC,.Ng requires Ce = 35-8 per cent.
(K,Ce),(FeC,;N,,), „ Ce = 29-0

It is seen, therefore, that the triple salts are really mixtures of
double salts.

My best thanks are due to Prof. Campbell Brown for facilities for
conducting this work, and for valuable help and suggestions during its
progress.

Chemical Departmknt,

University of Liverpool.

1360 HOPE AND PERKIN : ACTION OF BROMO- AND OF 4-BROMO-

CLII. — The Action of Bromocyclohexane and of i-Bromo-
i-methyhjclohexayic on the Sodium Derivative of
Ethyl Malonate.
By Edward Hope and William Henry Perkin, jun.

Tnis investigation was commenced in the hope of finding a convenient
method for the preparation of l-methylcyc/ohexylidene-4-acetic acid,

CHMe<^22*^g2>c:CH-C02H.

The first synthesis of this acid was carried out in the following
way (Perkin and Pope, Trans., 1908, 93, 1076): Ethyl 1-methyl-
c?/cZohexane-4-(arboxylate (I) was reduced by sodium and alcohol to
l-methylc^/cZohexylcarbinol (II) ; this was then converted into 1-methyl-
cyc/ohexylcarbinyl bromide (III), from which l-methylc2/c^ohexyl-4-
acetic acid (IV) was obtained by the action of potassium cyanide and
subsequent hydrolysis.

CHMe<^^2;CH2^^jj.(-jQ^j,|. CHMe<^^^;^H^>CH-CH2-0H

(I.) (H.) '

CHMe<^g2;CH2-^pjj.^jj^g^ CHMe<^^2-CH2\^(^-g..(^jj^.(^Q^^

(III.) ' (IV.)

This acid was next converted, by the action of bromine, into a-bromo-
l-methylcyc^ohexyl-4-acetic acid (V), the ester of which, on treatment
with diethylaniline and subsequent hydroly.sis, yielded 1-methylcycZo-
hexylidene-4-acetic acid (VI).

CHMe<^'{j2;CH2^Q2.Qjjg^..gQ^^

'(V.)

(VI.) ^

This process had many disadvantages. In the fir^^t place the number
of operations which had to be carried out rendered the preparation a
very laborious one, but the most serious drawback was the fact that
the l-meLhylc//c^ohexylidene-4-acetic acid ultimately obtained was far
from pure. This was found to be due to the presence of considerable
quantities of l-methylcyc^ohexyl-4-acetic acid, the ester of which is
produced during the action of diethylaniline on ethyl a-bromo-1-
methylcyc^ohexyl-4-acetate V^y a process of reduction which is not

-1-METHYL-CYCLOHEXANE ON ETHYL SODIOMALONATE. IHGl

easily followed. In the present series of experiments the first step was
the study of the action of bromocyc/ohexane on the sodium derivative
of ethyl malonate, a decomposition which leads to the formation of
ethyl cjclohexylmalonate,

CH2<CQjj".Qjj"/"CH*CH(C02Et)2.

This ester yields, on hydrolysis, cycloltexylmalonic acid (m. p.
176 — 178°), and this is decomposed at 180° into carbon dioxide and
cyclohexylacetic acid (m. p. 29°),

Ethyl cyc^ohexylmalonate reacts readily with bromine with
evolution of hydrogen bromide and formation of ethyl a-bromocyclo-
hexy I malonate,

and a-bromocyclohexylmalonic acid (m. p. 149 — 151°) is readily
obtained when the free acid is similarly treated.

Contrary to expectation, great difficulty was experienced in
bringing about the elimination of hydrogen bromide from ethyl
a-bromocyc/ohexylmalonate, such reagents as diethylaniline and
pyridine producing secondary decompositions, which caused reduction
and resulted in the formation of ethyl cyc^ohexylmalonate, whereas
methyl-alcoholic potassium hydroxide yielded ethyl a-methoxycjc\o-
hexylmalonate,

CH2<^^<^g-^>CH-C(OMe)(C02Et),,

and sodium ethoxide the corresponding eifAoccy-derivative.

When, however, the bromo-ester was digested with barium
hydroxide, the decomposition proceeded with elimination of hydrogen
bromide and formation of cyclohexylideneacetic acid (m. p. 90°), but
even in this case some reduction took place, and the product contained
c?/c/ohexylmalonic acid.

In the second series of experiments, we prepared ethyl 1-methyl-
cyclohexyl-i-malonate (VII) from 4-bromo-l-methylcycZohexane by the
action of the sodium derivative of ethyl malonate, and from this, by
hydrolysis, l-methijlcyc\ohexyl-'i-malonic acid (VIII), which melts at
177 — 178° with elimination of carbon dioxide and formation of
l-methylc2/c^ohexyl-4-acetic acid (m. p. 73°; IX), which had already
been prepared by Perkin and Pope (Trans., 1908, 93, 1079) by a
different process.

In the hope of converting ethyl l-methylc?/cZohexyl-4-malonate, or
the free acid, into l-methylc2/c?ohexylidene-4-acetic acid, we prepared
the bromo- derivatives of these substances and treated them with

1362 HOPE AND PERKIN : ACTION OF BROMO- AND OF 4-BnOMO-

(liethylaniline and pyridine under different conditions, hut in all cases
a complicated process took place, with formation of considerable

CHMe<^g;^:^g2>CH-CH(C02Et)2
(VII.)

' (VIII).

(IX.)
quantities of l-methylcycZohexyl-4-acetic acid, and we were unable to
isolate the unsaturated acid from the product of any of these
reactions. Treatment with methyl-alcoholic potassium hydroxide
converted the bromo-ester into a-methoxi/-l-methylcyc\ohexi/lnialomc
acid,

CHMe<^{{2;CH2\,gjj-C(OMe)(C02H)2

(compare p. 1368). When, however, ethyl a-bromo-l-methylcycZo-
hexyl-4-malonate was hydrolysed with barium hydroxide, it was
readily decomposed, with formation of l-methylcjclohexijl-i-tartronic
acid and l-methylcycZohexylidene-4-acetic acid,

CUM.e<^^\^^^>GK'C{011){G0^TI), and

CHMe<^^2;^^2>c:CH-C02H,

but the yield of the latter acid was quite unsatisfactory.

The most remarkable point in connexion with this and previous
researches on the same subject is the difficulty which has been
experienced in eliminating hydrogen bromide from a-bromo-esters of
the types :

(~^^2>cH-CBr(C02Et)2 and ("^^s^cH-CHBr-COaEt,

that is, containing a closed ring, whereas it is well known that this
process takes place with great ease in the case of open-chain a-bromo-
esters. Thus, for example, ethyl a-bromoisovalerate,

OHMeg-CHBr-COgEt,
is very readily converted into ethyl dimethylacrylate, CMegXH'COgEt,
when it is digested with diethylaniline.

It is fortunate that, owing to the elegant method of formation
recently devised by Wallach {Annalen, 1909, 365, 263), 1-methyl-
cycZohexylidene-4-acetic acid may now be pi^epared in considerable
quantities with comparative ease.

-1-METHYL-CYCLOHEXANE ON ETHYL SODIOMALONATE. 1363

Experimental.
Ethyl cyc\oHexylmalonale.

The bromocycZohexane required for the synthesis of this substance
is readily prepared by heating a mixture of cycZohexanol (100 grams)
with acetic-hydrobromic acid (200 grams, saturated at 0°) for half an
hour on the water-bath. The product is poured into water, the heavy
oil. extracted with ether, the ethereal solution washed with
water and then with sodium carbonate until free from acetic acid,
dried, and distilled, when almost the whole quantity passes over at
113 — 116°/150 mm., and consists of bromocycifohexane mixed with
small quantities of unchanged cycZohexanol.

The prepai-ation of ethyl cycZo hexylmalonate is carried out as
follows : Sodium (8'7 grams) dissolved in alcohol (150 c.c.) is well-
cooled, mixed with ethyl malonate (60 grams) and bromocycZohexane
(62 grams), and the whole heated on the water-bath for twenty-four
hours. After adding water, the product is extracted with ether, the
ethereal solution well washed, dried, evaporated, and the residue
repeatedly distilled under diminished pressure, when, after an oil of
low boiling point, consisting chiefly of cycZohexene, cycZohexanol, and
ethyl malonate, has passed over, a considerable fraction is obtained
distilling constantly at 163 — 165°/20 mm. :

0-1777 gave 0-4193 CO2 and 0-1438 HgO. C = 64-3; H = 9-0.
CjgHggO^ requires 0 = 64*4 ; H = 9-l per cent.

Ethyl cyciohexyhnalonate is a colourless, viscid oil, and is obtained
in the above process in a yield of about 33 per cent, of that
theoretically possible. Although it probably yields a sodium
derivative, attempts to introduce a second cyclohexyl group by treating
the pure ester with sodium ethoxido and bromocycZohexane gave a
negative result.

cjcloHexylmalonic Acid and cycloHexylacetic Acid.

The hydrolysis of ethyl C7/c^ohexylmalonate takes place readily when
the ester is digested with a slight excess of methyl-alcoholic potassium
hydroxide on the water-bath, and, after one hour, the crystalline
potassium salt which will have separated is collected, dissolved in
water, and acidified with hydrochloric acid.

The solid acid is well washed and crystallised from formic acid,
from which it separates in long, glistening prisms :

0-1242 gave 0-2653 CO2 and 0-0866 H2O. C = 58-2 ; H = 7-7.
CtjHj^O^ requires C = 58-0 ; H = 7*5 per cent.

cy do Hexylmalonic acid melts at 176 — 178'^ and decomposes into

1364 HOPE AND PERKIN : ACTION OF BROMO- AND OF 4-BROMO-

carbon dioxide and c?/cZohexylacetio acid ; it is moderately readily
soluble in warm water, and sepax^ites on cooling in small prisms. It
is readily soluble in ether, slightly so in chloroform, and almost
insoluble in benzene or light petroleum. The basicity of this acid was
determined by titration with ^\710-sodium hydroxide, when 0-362 gram
neutralised 0'0146 NaOH, whereas this amount of a dibasic acid,
CjHi^O^, should neutralise 0-0153 NaOH.

If the pure acid is heated at 180°, a vigorous evolution of carbon
dioxide takes place, and when this has ceased, the residual, nearly pure
c?/c^ohexylacetic acid solidifies, and may be purified by crystallisation
from formic acid :

0-1700 gave 0-4175 CO., and 0-1529 HgO. 0 = 66-9; H = 9-9.
CgHj^O^ requires 0 = 67-6 ; H = 9-8 per cent.

cyc\o Hexylacetic acid separates from formic acid in ill-defined plates,
and, after pressing on porous porcelain and drying over sulphuric acid,
the acid melts at about 28 — 29°.

a-Bromocjclohexylmalonic A cid.

This acid is best prepared by adding bromine (0-4 c.c.) to a solution
of cycZohexylmalonic acid (1 gram) in carefully dried ether.

After remaining for four hours, the solution is warmed for a short
time on the water-bath and the ether allowed to evaporate at the
ordinary temperature, when a solid residue is obtained which crystal-
lises from formic acid in magnificent rhombic plates :

0-1385 gave 00970 AgBr. Br = 29-8.

CglljgO^Br requires Br= 30-2 per cent.

a-Bromocyclohexylmalonic acid melts at 154 — 156°, and is very
soluble in ether, moderately so in chloroform, and very sparingly so in
water or benzene.

Oonsiderable quantities of ethyl a-bromocyc?ohexylmalonate were
prepared by adding bromine (4-7 c.c), drop by drop, to pure ethyl
c?/c^ohexylmalonate (21 grams) at the ordinary temperature.

The bromine was rapidly absorbed, with the evolution of hydrogen
bromide, and, after remaining for three hours, the whole was dissolved
in ether, the ethereal solution washed with dilute sodium carbonate,
dried, evaporated, and the residual syrup fractionated under diminished
pressure :

01 234 gave 00736 AgBr. Br = 25-4.

CjgHjiO^Br requires Br = 24-9 per cent.

Ethyl a-bromocyc\ohexylmalonate distils at 183 — 185°/ 20 mm.

-1-METHYL-CYCLOHEXANE ON ETHYL SODIOMALONATE. 1365

Attempts to Eliminate Hydrogen Bromide from
Ethyl a-Bromocyc\ohexylmalonate.

These experiments were undertaken with the object of determining
the conditions under which cyc^ohexylideneacetic acid,

CH2<^2<^{{2>c:cH-co,Tr,

is produced from ethyl a-bromocyc^ohexylmalonate.

I. The Action of Diethylaniline and of Pyridine. — In the first experi-
ment the bromo-ester (15 grams) was added to boiling diethylaniline
(25 grams), and, after continuing the boiling for four hours, the dark
opaque liquid was cooled, poured into dilute sulphuric acid, and
extracted with ether. The dark ethereal solution was washed with
dilute sodium carbonate, dried, evaporated, and the residue distilled,
when a small quantity of oil was obtained boiling at 155 — 165720 mm.
This, on hydrolysis with methyl-alcoholic potassium hydroxide, yielded
an acid melting at 175 — 176°, which, on examination, proved to be
cyc^ohexylmalonic acid. In a second experiment, the same quantities
were heated at 120° for five hours, when the product was found to
consist of about two-thirds unchanged bromo-ester and tariy matter,
from which nothing definite could be isolated.

The bromo-ester (20 grams) was next digested with pyridine (SO c.c.)
for five hours on the water-bath, when the product, extracted in the
usual manner, distilled at 180 — 185°/20 mm., and consisted of
unchanged bromo-ester, almost the whole quantity being recovered.
When the experiment was repeated at the boiling temperature for six
hours, about 40 per cent, of the bromo-ester was recovered, and the
remainder consisted principally of uninviting tarry matter.

II. The Action of Potassium Hydroxide. — Ethyl a-bromocycMiexyl-
malonate is scarcely attacked by boiling with 30 per cent, aqueous
potassium hydroxide, but weaker alkali gradually decomposes it,
with the formation of considerable quantities of cyc^ohexylmalonic
acid.

When the bromo-ester (23 grams) was digested with a strong
solution of potassium hydroxide (40 grams) in methyl alcohol,
potassium bromide soon separated, but the potassium salt of the
organic acid remained dissolved in the alcohol. In order to isolate
this acid, the product was evaporated to dryness, the residue powdered,
suspended in alcohol, and saturated with hydrogen chloride, and, after
remaining for several hours, water was added and the ester extracted
with ether.

The ethereal solution was washed with sodium carbonate, which
removed considerable quantities of an acid-ester, and the latter was
again esterified. The combined esters were then fractionated, when

1366 HOPE AND PERKIN : ACTION OF BROMO- AND OF 4-BROMO-

a considerable quantity of an oil was obtained, which distilled at
about 1 65720 mm., and evidently consisted of ethyl a-methoxycyc\o-
hexyhnalonate :

0-2144 gave 0-4890 CO2 and 0-1678 HgO. C = 62-2j H = 8-7.

0-2006 „ 0-4548 CO2 „ 0-1524 H.p. 0 = 61-7; H = 8-4.
C14H2A requires 0 = 61-7; H = 8-8 per cent.

On hydrolysis with alcoholic potassium hydroxide, this ester yielded
a syrupy acid, which was not further investigated.

The nature of this change was confirmed by the investigation of the
action of sodium ethoxide on ethyl a-bromocyc?ohexylmalonate.

The bromo-ester (16 grams) was poured into a solution of sodium
(3*5 grams) in alcohol (45 c.c), when immediate decomposition took
place, the liquid became quite warm, and a yellow solid separated.

After heating for half an hour on the water-bath, the product was
isolated in the usual manner and fractionated, when almost the whole
quantity distilled at about 165°/20 mm., and evidently consisted
of ethyl a-ethoxycyclohexyl7nalo7iate :

0-1704 gave 0-4016 00^ and 0-1379 H,0. 0 = 64-3 ; H = 9-0.
O^jjEEggOs requires 0 = 64-0 ; H = 9-3 per cent.

III. The Action of Barium Hydroxide. Forvfiaiion of cyclo-
Hexylideneacetic Acid. — In this experiment ethyl a-bromocyc^ohexyl-
malonato (15 grams) was digested with a strong aqueous solution
of barium hydroxide (45 grams) for five hours. The product was
kept until cold, filtered from excess of barium hydroxide, mixed
with ice, and acidified, when an immediate separation of needle-
shaped crystals took place. The precipitate was collected, washed,
recrystallised from dilute methyl alcohol, and analysed, with the
following result :

0-1434 gave 0-3616 OO2 and 0-1158 HgO. 0 = 68-8; H = 8-9.
OgHjgOg requires 0 = 68*6 ; H = 8-6 per cent.

This acid melted at 89 — 90°, and proved, on examination, to be
c?/c?ohexylideneacetic acid, since when mixed with a sample of this
acid which had been obtained by another process (Wallach, Annalen,
1909, 365, 261), there was no alteration in melting point.

The aqueous liquors from which this acid had separated yielded, on
extraction with ether, an oily acid, which gradually solidified, and
after crystallisation, first from formic acid and then from water,
melted at 175 — 176° and consisted of cyc^ohexylmalouic acid :

0-1394 gave 0-2937 OO2 and 0-0937 H.p. 0 = 57-5 ; H = 7-4.
OglljA requires 0 = 58-0; 11 = 7*5 per cent.

-1-METHYL-CYCLOHEXANE ON ETHYL SODIOMALONATE. 1367

l-Melh>/lcyc\ohexi/l-i-inalo7tic Acid and its Derivatives.

Since the experiments on the preparation, properties, and decom-
positions of this acid were carried out on the same lines as those
described in detail in the case of cyc^ohexylmalonic acid, it will only
be necessary to refer to them briefly.

A:-Bromo-\-methylcyc\ohexane was prepared by the action of acetic-
hydrobromic acid on l-methyl-4-cyc^ohexanol, and distilled at
i24 — 126°/150 mm. In preparing ethyl l-methylcy/c^ohexyl-4-
malonate, ethyl mulonate (80 grams), mixed with sodium (11-6 grams)
dissolved in alcohol (200 c.c), was digested with bromomethylcy/c^o-
hexane (90 grams), and the product isolated in the usual manner.
It distilled at 163 — 165°/20 mm., and gave, on analysis, the following
result :

0-1924 gave 0-4612 COg and 0'1672 HgO. C = 65-3 ; li = 9-6.
^i4^24*-*4 J^equires C = 65-6 ; H = 9-6 per cent.

When this ethereal salt was hydrolysed with methyl-alcoholic
potassium hydroxide, it yielded a sparingly soluble 2^ol'<^''^^^'^'>^^ salt,
from which the free acid was obtained by acidifying with hydrochloric
acid :

0-1395 gave 0-3038 CO^ and 0-0998 H^O. G = 59-4 ; H = 7-9.
CjqHjijO^ requires C = 60-0 ; H = 8-0 per cent.

The basicity was determined by titration with iV/lO-sodium
hydroxide, when 0-244 gram neutralised 0-0972 NaOH, whereas this
amount of a dibasic acid, CjQH-^gO^, should neutralise 0-0976 NaOH.

l-Methylcyc\ohexyl-4:-malonic acid melts at 177 — 178°, and decom-
poses into carbon dioxide and l-methylc?/c^ohexyl-4-acetic acid; the
latter separated from formic acid in pearly plates, melted at 73°, and
was identical with the acid of this constitution which Perkin and
Pope (Trans., 1908, 93, 1075) had prepared by a different method.
In preparing ethyl a-bronio-l-7nethylcjclohexyl-4i-malonate, ethyl 1-
methylcyc^ohexyl-4-malonate (20 grams) was gradually treated with
pure bromine (4-2 c.c), and, as soon as the reaction was complete, the
product was extracted with ether, the ethereal solution washed with
sodium carbonate, dried, and distilled, when almost the whole quantity
passed over at 182 — 185°/20 mm. as a viscid, colourless syrup :

0-1330 gave 0-0758 AgBr. Br = 24-2.

C^^^HggO^Br requires Br = 23-9 per cent.

a-Bromo-l-methylcjclohexyl-4:-7nalonic acid was obtained by the
action of bromine on the pure acid, and separated from formic acid
in glistening prisms melting at 149 — 151°:

0'1183 gave 0-0800 AgBr. Br = 28-7.

Cjyli^jjO^Br requires Br= 28"7 per cent.

1368 HOPE AND PERKIN : ACTION OF BKOMOCYCLOHEXANE, ETC.

Attemptt) to Eliminate Hydrogen Bromide from Ethyl <x-Bromo-\-methyl-
cyaXohexylA-malonate.

When this bromo-ester was treated with diethylaniline or pyridine
under the conditions described in the case of ethyl a-bromocyc^ohexyl-
malonate (p. 1365), much tarry matter was produced, and the only
definite substance which could be isolated was ethyl 1-methylcycZohexyl-
4-malonate. The bromo-ester reacts readily with methyl-alcoholic
potassium hydroxide at the temperature of the water-bath, yielding
potassium bromide and a sparingly soluble j^otassium salt, and, when
this salt is acidified, a gum separates, which doubtless consists of
a-methoxy-l-methylcyc^ohexyl-4-malonic acid, but as it did not solidify,
the whole was esterified with alcohol and hydrochloric acid (compare
p. 1365) and the ester fractionated. The oil distilling at about
168 — 173°/20 mm. consists of ethyl a-7nethoxy-l-methylcyclohexyl-4:-
malonate :

0-1571 gave 0-3640 CO2 and 0-1235 H2O. 0 = 632; H = 8-7.

0-2158 „ 0-5010 CO.2 „ 0-1726 H2O. 0 = 63-3 ; H = 8-8.
CjgHggOg requires 0 = 62-9 ; H = 9-l per cent.

I'he Action of Barium Hydroxide on Ethyl a-Bromo-\-viethylcyc\ohexyl-
4:-malonate. — As this action proceeds in a different manner from the
corresponding decomposition of ethyl a-bromoc?/c^ohexylmalonate
(p. 1366), it is necessary to describe it in detail.

The bromo-ester (15 grams) was boiled for five to six hours with a
strong solution of barium hydroxide (45 grams), when a sparingly
soluble barium salt gradually separated. This was collected, decom-
posed by hydrochloric acid, and extracted with ether, when a syrupy
acid was obtained, which, over sulphuric acid in a vacuum desiccator,
partly crystallised. In contact with porous porcelain the oily portion
was readily absorbed, leaving a colourless, crystalline residue, which
separated from formic acid in rhombic plates, and consisted of
\-methylcyc\ohexyl-4:-tartronic acid :

0-1267 gave 0-2567 CO2 and 00849 HgO. 0 = 55-2; H = 7-4.
OjoHjgOg requires 0 = 555; H = 7'4 per cent.

The constitution of this acid was demonstrated by heating it at
160°, when it decomposed with elimination of carbon dioxide and
formation of a mixture of a-hydroxy-l-methylc?/cZohexyl-4-acetic acid
and l-methylc3/c^ohexylidene-4-acetic acid. The product was distilled
in a current of steam and the residue extracted with ether, when a
solid acid was obtained, which, after crystallisation from formic
acid, melted at 143^ and was identical with a-hydroxy-l-methylcyc^o-
hexyl-4-acetic acid described by Perkin and Pope (Trans., 1908, 93,
1075):

THE HYDUOLYSIS OF AMYGDALIN 1?Y ACIDS. PART I. 1369

0-1 196 gave 02725 CO,, and 0-0979 H,0. C = 62-l ; H = 9-l.
CyHj^jOg requires C = 62-8 ; H = 9-3 per cent.

The steam distillate (and also the soluble barium .salt from tlie
hydrolysis described above) contained an oily acid, which, although it
did not solidify, evidently consisted largely of l-methylcyc^ohexylidene-
4-acetic acid. This was shown by analysis and by the fact that,
when oxidised by permanganate, it yielded considerable quantities of
l-methyl-4-c?/c^ohexanone, which was easily identified by its general
properties and by the melting point of its semicarbazone.

The Schunck Laboratory,
The University,
Manchester.

CLIII. — The Hydrolysis of Amygdaliii by Acids.

Part I.

By J. Wallace Walker and Vernon K. Krieble.

Although this subject has been stvidied by several investigators,
and varying results have been obtained according to the different
experimental conditions employed, we find that, as yet, no com-
pletely systematic examination has been made, and consequently
have commenced to carry it ovxt in detail. The fact that
amygdalin, when heated with dilute aqueous solutions of the
strong acids, yields the same prodvicts as when treated with
emulsin, namely, dextrose, benzaldehyde, and hydrocyanic acid,
was first established by Ludwig {.Jahresh., 1855, 699). In a com-
paratively recent communication, Caldwell and Courtaiild (Trans.,
1907, 91, 666) have shown that this change involves a succession
of reactions, the first of which consists in the hydrolytic elimination
of one molecule of dextrose, and they have succeeded in isolating
Fischer's Z-mandelonitrile glucoside as an intermediate product,
thus showing that the first jooint of the amygdalin molecule,
CeH5-CH(CN)-0-C6Hjo05-C(5Hii05, to be attacked by dilute hydro-
chloric acid is the biose junction, just as when maltase is employed
as hydrolyst (Fischer, Ber., 1895, 28, 1508). There are, however,
two other points in the molecule of amygdalin susceptible of
hydrolysis, namely, the junction between the biose and the
mandelonitrile groups, and also the nitrile group itself. The well-
known formation of ^mandelic acid when concentrated hydro-
chloric acid is substitvited for dilute, might therefore be assumed
to indicate an entirely different behaviour on the part of the
VOL. XCV. 4 U

1370 WALKER AND KHIEBLE : THE HYDROLYSIS OF

concentrated acid, or it might mean that both dilute and con-
centrated acids act similarly at first, hydrolysing amygdalin to
dextrose and /-mandelonitrile, but differ in their subsequent action
on this substance, the latter hydrolysing it further to ammonium
chloride and Z-mandelic acid, whilst the former decomposes it to
benzaldehyde and hydrocyanic acid. The conclusion was, however,
deduced by one of us (Walker, Trans., 1903, 83, 472) that the
first point attacked by concentrated hydrochloric acid (D I'l)
is the nitrile group, which suffers hydrolysis to carboxyl, the
elimination of the dextrose groups taking place subsequently. The
entire course of the decomposition of the amygdalin molecule is
thus different, according as weak or concentrated hydrochloric
acid is employed as hydrolyst.

The above conclusion suggested the advisability of examining
the behaviour of other strong acids in aqueous solution, for,
although no difference in their action was to be anticipated on
theoretical grounds, the same might be said of a single acid, such
as hydrochloric, when employed at different concentrations.
Although the statement that all concentrated acids behave alike
in this respect has been generally accepted, it appears to be based
entirely on analogy, for we cannot find that anyone has examined
the behaviour of any acid other than hydrochloric acid. Experi-
mentally, we find that a concentrated aqueous solution of sulphuric
acid behaves in a totally different manner from one of hydro-
chloric acid, inasmuch as the former shows very little tendency
to attack the nitrile group, which, as already stated, is the
first point attacked by the latter. So slight indeed is this
tendency that a large amount of Z-mandelonitrile separates from
the solution as an oil, and it seems to be only very slowly acted
on further. Dilute sulphuric acid shows points of resemblance
both with dilute hydrochloric acid and with concentrated sulphuric
acid, inasmuch as it first removes one molecule of dextrose, pro-
ducing Fischer's Z-mandelonitrile glucoside, and then liberates
Z-mandelonitrile, on which it acts very slowly. Oxalic acid
probably behaves mainly in the same way as dilute hydrochloric
acid. Trichloroacetic acid has thus far only been examined in
fairly concentrated solutions. Its behaviour is entirely anomalous,
for it does not appear to effect the hydrolysis of amygdalin at all
under conditions which enable hydrochloric acid to act fairly rapidly.

Experimental.

Hydrolysis hy Dilute Hydrochloric Acid. — The hydrolytic action
of normal acid has been quantitatively studied by Caldwell and
Courtauld {loc. cit.). They have shown that at temperatures of

AMVGDALIN RY ACIDS. PART I. 1371

60° and 80° the junction of the two dextrose groups is first
attacked with the formation of dextrose and Fischer's Z-inandelo-
nitrile glucoside, which on further hydrolysis yields a second
molecule of dextrose and the decomposition products of /-mandelo-
nitrile, namely, benzaldehyde and hydrocyanic acid.

Hydrolysis hy Concentrated Hydrochloric Acid. — The action of
concentrated hydrochloric acid solution (D Tl) on Z-amygdalin,
/•-amygdalin, and r-amygdalinic acid at 20° was examined by one
of us (lor. cif.), the accompanying change of rotation being
followed polarimetrically. In the case of ^amygdalin there was
a large and rapid increase of laevorotation, followed by a much
slower but greater decrease, whereas r-amygdalin showed prac-
tically no change during the first period, but an equal diminution
of laevorotation during the second. There are three possible initial
paths by which the hydrolysis may proceed, namely:

(a) Amygdalin — >- mandelonitrile + biose,
{b) Amygdalin — >■ mandelonitrile glucoside + dextrose,
and (c) Amygdalin — >- amygdalinic acid + ammonia.

Of these three, (b) is at once excluded by the observed large
initial increase of Icevorotation when using ^amygdalin, since
Z-mandelonitrile glucoside has a smaller hevorotation than that
substance. Finally, (c) was indicated as the path selected by
observing the behaviour of r-amygdalinic acid when similarly
hydrolysed. Its rotatory power changed in a manner corresponding
with the second period of /'-amygdalin. Attempts to isolate the
/-amygdalinic acid having been unsuccessful, the hydrolysis by
concentrated hydrochloric acid has been further studied with
different concentrations of acid and at different temperatures, and
confirmation of the above conclusion has been sought and obtained
in other ways. A solution was prepared containing 10 grams of
Z-amygdalin in 50 c.c. of hydrochloric acid (D 1"118), and allowed
to reach the condition of n'laximum laevorotation. It was then
extracted with benzene, but gave no trace of ^mandelonitrile. The
acid solution was then neutralised with sodium hydroxide
to decompose any possible compound of hydrochloric acid
with the nitrile, and again extracted with benzene, but no
mandelonitrile was obtained on evaporation of the benzene. A
similar solution, after attaining the maximum activity, was diluted
with sufficient water to reduce the strength of the hydrochloric
acid to normal, and then heated for eight hours in a closed vessel
on the boiling-water bath. Neither benzaldehyde nor hydrocyanic
acid could be detected in it after this treatment. These experi-
ments prove conclusively that the hydrolysis does not take place
according to (a). In the former communication the change of

4 U 2

1372

WALKER AND KRIEBLE : THE HYDROLYSIS OF

rotation was not followed far past the maximum point, con-
sequently there was no evidence obtained of the subsequent course
of the hydrolysis of the /-amygdalinic acid, which may proceed by
one of two paths, either :

(d) ^-Amygdalinic acid — >- ^mandelic acid-f biose,
or (e) ^Amygdalinic acid — > ^mandelic acid glucoside + dextrose.

To gain information on this point, a series of observations have
been made, covering the whole time of action or the major part
of it. Some of the results obtained are given in the following
tables. The material employed in (I) was Kahlbaum's, having
the composition C2oHo>.Oj^N,2H20, that in (II) and (HI) had
been recrystallised from water and had the composition
C2oHo70iiN,3HoO. In comparing the maximum rotation attained
in (I) with those in (II) and (HI), the former must therefore be
multiplied by 493/511. Each solution contained 10 grams of
material in 50 c.c, and was examined in the 2-dcm. tube:

Table I.
Temperature 28°. Hydrolyst: Hydrochloric acid (D 1089).

Time in hours.

Qd-

Time in hours.

at,.

0-5

-13-5°

90

-38-5"

3-75

15-4

97

39-22

18-25

24-34

115

39-88

24-5

26-5

140

39-14

42 -0

321

161

39-14

67-0

36-4

186

38-0

72 0

36-9

Table II.

Temperature

28°. Hydrolyst: Hydrochloric acid

(D 1-1]

Time in hours.

a„.

Time in hours.

a I,.

016

-15-0°

23-16

-39-10°

2-52

27-3

29-9

36-4

5-1

35-1

39-17

.32-86

9-33

40-4

43-0

31-4

11 •7.')

41-8

.52-25

28-0

12-16

41-9

55-50

27-0

14-0

41-5

72-75

22-3

18-0

40-4

84-0

19-7

Temperature 60^

Table III.
Hydrolyst: Hydrochloric acid (D TllS).

Time in minute.".

Ov

Time in mi

nutes.

Ob.

3

-14-3°

5d

-17-7°

11

19-2

68

15-7

16

21-9

83

12-00

21

22-4

96

9-0

29

22-7

115

6-3

37

21-4

135

4-3

45

19-7

175

2-0

AMYGDALIN BY ACIDS. PART I. 1373

The observations in table III, where the hydrolysis has been
carried to completion, do not, even when plotted in the form of a
curve, show a separation into the three distinct reactions which
must take place, consequently two of them must proceed with
approximately the same velocity. Experiments were therefore
made to determine the amount of chemical change which had
taken place corresponding with definite changes in optical power.
The solutions employed contained 10 grams of the compound
C2oH270,iN,2H.,0 in 50 c.c, and the diluent was hydrochloric
acid (D ril8). In the first experiment, the rotation was
Op — 30" 25° after the solution had remained at 35° for ninety-six
minutes, and it was found to contain reducing sugar equivalent to
8 per cent, of the total quantity of dextrose which 10 grams of
amygdalin could yield. A portion of it, after neutralisation with
sodium hydroxide, was heated for twenty-two hours at 40° with
emulsin, and the liberated hydrocyanic acid was titrated with
.V/50-iodine solution in order to determine how much remained
as cyanogcnetic glucosidc. It was found that only 8 per cent, of
the hydrocyanic acid, corresponding with 10 grams of amygdalin,
was thereby liberated. Up to this point, therefore, the reaction
had consisted mainly in the production of Z-amygdalinic acid,
although the formation of some reducing sugar shows that another
slower reaction is proceeding conteraporaneovxsly. In a second
experiment, the rotation in the 2-dcm. tube after the solution had
remained at 38'5° for 230 minutes was — 35'9°, and this was the
maximum reading attained at that temperature. Estimations
similar to the above showed that the solution now contained
reducing sugar equivalent to 21 per cent, of the total quantity
of dextrose obtainable from 10 grams of amygdalin, and that there
still remained 5 per cent, of the amygdalin as a cyanogenetic
glucoside. These observations, while confirming the conclusion
regarding the first action of hydrochloric acid in producing
Z-amygdalinic acid, are not in themselves decisive as to whether a
biose is liberated or not in the second stage. If liberated, however, it
must be very strongly laevorotatory to account for the great observed
increase of laevorotation as the reducing sugar increases in amount,
but, since there is no corresponding increase of laevorotation during
the hydrolysis of /--amygdalinic acid under the same conditions, it
follows that biose is not liberated, and consequently that (c) and
(e) represent the course of the hydrolysis. The point of maximum
optical activity of the solution, however, does not correspond with
that of maximum content of /-amvgdalinic acid, and the difficulty
which, as already stated, was experienced in our attempts to
isolate that substance by stopping the hydrolysis at the point of

1374 WALKER AND KRIEBLE : THE HYDROLYSIS OF

maximum optical effect is thus entirely explained, for the solution
then contains, besides that acid, an amount of free dextrose and
of Z-mandelic acid glucoside equivalent to 42 per cent, of the
amygdaliu employed. It is also evident, from the above tables,
that the change in the velocity of the reaction for a comparatively
small change in the concentration of the hydrolyst is very great.
The concentrations of hydrochloric acid in the two experiments at
28° are in the ratio of 10 to 13, but the more dilute solution takes
ten times longer to reach its maximum. Further, the maximum
rotation attained is highest at low temperatures and with stronger
acid, but whether this points to a change in the relative velocities
of the several reactions has not yet been determined.

Hydrolysis by Concefitrafed Aqueous Solutions of Sulphuric
Acid. — A solution containing 40 grams of sulphuric and 20 grams
of amygdalin in 60 grams of water was heated on the water-bath
to 90°. After a qviarter of an hour it had become turbid, and
on heating for an hour longer a layer of dark oil was found
floating on its surface. This was extracted with benzene, and
found to be strongly dextrorotatory in that solvent. On evapora-
tion of the benzene there remained 4'573 grams of oil without any
odour of benzaldehyde. The theoretical yield of mandelonitrile
is 5 '4 grams. On cooling, it crystallised and melted a little above
20°. It was hydrolysed by heating with concentrated hydro-
chloric acid solution, and evaporated to dryness on the water-bath.
The mandelic acid was extracted from the residue with ether, and
the ammonium chloride collected. It weighed r823 grams instead
of the theoretical 1"8395 grams. The oil was therefore nearly
pure Z-mandelonitrile, and was obtained in 85 per cent, yield.
The aqueous sulphuric acid solution was twice extracted with ether,
and gave 0"8 gram of mandelic acid, which showed [ajp — 74°. It
had therefore been racemised to a considerable extent. This
experiment shows that the first point in the amygdalin molecule
attacked by a concentrated aqueous solution of sulphuric acid is
totally different from that acted on by concentrated hydrochloric
acid; in fact, what the ons attacks first the other attacks last, and
apparently with difficulty. In a second experiment a lower con-
centration of sulphuric acid was employed. On heating 10 grams
of amygdalin with 50 c.c. of 2"77iY-sulphuric acid to 98° for
three hours, a dark oil separated, which was extracted with benzene.
This solution, having a volume of 50 c.c, showed a rotation of
a^+l'l° in the 1-dcm. tube, and left on evaporation of the benzene
1"75 grams of oil, which was shown, as before, to be ^mandelo-
nitrile. From the above data its specific rotation in benzene

AMYGDALIN BY ACIDS. PART I. 1375

solution is approximately [a]j,+ 3r4°. The yield in this instance
was only 65 per cent.

Hydrolysis by Dilute Aqiieotis Sul'phuric Acid. — The strength
of sulphuric acid employed in the three following experiments was
1 01 353'. A solution containing 2 grams of amygdalin in 10 c.c.
of this acid, afte • heating at 98° for three hours, remained quite
clear when cooled. When heated at the same temperature for one
hour longer it became milky when cold, and, after two hours'
further heating, there were beads of oil floating on the solution,
and it had acquired a distinct odour of oil of bitter almonds. A
similar solution was heated at 98° for two hours. It was then
neutralised, and the reducing sugar estimated. It corresponded
■with 0"86 gram of dextrose, whereas 2 grams of the amygdalin
employed, having the compo.';ition C.2qH2-Oi|N,2H20, should yield
on complete hydrolysis r488 grams of dextrose. On repeating-
this experiment with a larger amount of material, its rotation in
the 1-dcm. tube was aj3 + 0"85°, whereas, had hydrolysis to dextrose
and /-mandelonitrile glucoside been quantitative, it should have
been approximately +07°. The solution was exactly neutralised
with a standard solution of barium hydroxide, and, after the
barium sulphate had settled, the clear liquid was decanted and
evaporated to a thick syrup in a vacuum. It was. then extracted
with a small quantity of boiling alcohol, and this solution frac-
tionally precipitated by ethyl acetate. The first crop was obviously
impure /-mandelonitrilc glucoside, as its specific rotation was
[a]p — 18"1°, but subsequent crops approximated more closely to
the value for that substance, namely, [aj^ — 265°, and on re-
crystallisation the correct value was obtained. The results of
these experiments show that the biose junction in the molecule of
amygdalin is the point most susceptible of attack by sulphuric
acid at all concentrations, just as when dilute hydrochloric acid
is employed. They demonstrate, however, the striking difference
between the comparative facility with which the latter acid decom-
poses benzaldehydecyanohydrin and the difficulty with which that
is accomplished by sulphuric acid. After heating to 80° for two
hours with xY-hydrochloric acid, Caldwell and Courtaixld {loc. cit.)
estimated that the solution contained hydrocyanic acid equivalent
to 14 per cent, of the amygdalin employed, whereas in our experi-
ments with dilute sulphuric acid the amount present must have
been extremely small, for the odour of oil of bitter almonds could
not be detected with certainty.

Hydrolysis by a Concentrated Aqueous Solution of Oxalic Acid.
— This acid has only been examined in concentrated solution, and

1376 WALKER AND KRIEBLE : THE HYDROLYSIS OF

even thus at a temperature of 98° its action is very slow relatively
to that of hydrochloric and sulphuric acids. An aqueous solution,
containing 9"45 grams of crystallised oxalic acid and 10 grams of
amygdalin in 50 c.c, was lieated on the water-bath at 98° for
intervals of three, five, and seven hours, and estimations were
made of the liberated hydrocyanic acid and reducing sugar. The
results were as follows :

Time.

D(.'xtiose.

Hyrl

locyanic acid

3

400

14-8

5

51-7

24-5

7

59-5

30 0

The results are expressed in percentages of the total amounts
which 10 grams of amygdalin could yield. It seems probable from
these figures that oxalic acid resembles dilute hydrochloric in its
action, producing first Z-mandelonitrilc glucoside, which it subse-
quently hydrolyses to dextrose, and the decomposition products of
mandelonitrile, but the production of ^mandelic acid in small
amount is not excluded. To test for this, an experiment was
performed, using six times the quantity of material, and the heating
was continued for four hours longer. It was then thoroughly
extracted with ether, and the residue left on evaporation of the
ether was converted into the barium salt. After filtration from
a considerable quantity of barium oxalate, the filtrate was
evaporated to dryness, and the soluble acid again extracted with
ether after acidifying with hydrochloric acid. There were thus
obtained 1387 grams melting at 118 — 126° and showing
[a]jj— 136°. The corresponding values for pure /-mandelic acid are
132° and —154°. It was therefore mainly /-mandelic acid con-
taminated with a little of the racemic acid, which melts at 118°,
and the yield was about 8 per cent, of the theoretical. Although
Caldw-ell and Courtauld did not succeed in demonstrating the
production of this substance when i\'^ -hydrochloric acid is employed
as hydrolyst, it is not improbable that a small quantity is produced
in that case also.

Trichloroacetic Acid. — A solution containing 10 grams of
amygdalin, 36 grams of acid, and 25 c.c. of water, having a total
volume of 55 c.c, was kept at 18°. It required several hours for
total solution. Its rotation in the 1-dcm. tube was Cp — 83°, and
this remained constant for four weeks. The solution is 4iV
with respect to acid, and, as no determinations had been made
with a corresponding strength of hydrochloric acid at that tem-
perature, a solution was made up containing 10 grams of amygdalin
in 55 c.c, the diluent being 4"4iV^-hydrochloric acid. In contrast
to the above, its rotation in the 1-dcm. tube varied in sixteen

AMYGDALIN «Y ACIDS. PART I. 1377

days from Op — 7"7° to — 20'0o°. The solution containing tri-
chloroacetic acid was then heated for twenty-four hours at 45°,
but when cooled and again examined its rotation was found to be
unaltered. Thinking that the relatively small quantity of water
present in this solution might be responsible for such an anomalous
result, we diluted 10 c.c. of it to 1^0 c.c. The observed angle was
now Oj, — 415°, and it remained constant during nineteen days
at 18°. Trichloroacetic acid, therefore, does not appear to hydro-
lysc amygdalin at all under conditions similar to those at which
hydrochloric acid effects complete hydrolysis.

The hydrolytic activity of acids is commonly ascribed to the
hydrogen ion which they contain, and this property has been
employed in a great number of well-known instances as a measure
of the relative affinity of the acids. Further, a large number of
other methods have been developed for measuring the affinities of
acids, and these, although not yielding absolutely concordant
results, nevertheless give vakies for any particular acid which arc
at least of the same order of magnitude. All of these methods
indicate that trichloroacetic acid is not quite, but nearly, as strong
as hydrochloric acid. However, as regards their power of hydro-
lysing amygdalin, we find that the two do not even appear in the
same category. The amygdalin molecule is, however, exceptional
among the hydrolysts which have been examined, in that it has
several points, totally different from each other in their chemical
nature, susceptible to the action of the hydrolyst, and it may well
be that a similar examination of other substances presenting such
features will show parallel behaviour. In a recent investigation,
Adrian J. Brown {rroc. Boy. Soc, 1909, B, 81, 82) has found an
instance of selective action on the part of some acids. He has
observed that whilst the coverings of the seeds of Ilordeum vulgare
are readily permeable to trichloroacetic acid in aqueous solution,
they are quite impermeable to hydrochloric and sulphuric acids.

It would be idle at present to suggest an explanation of this
anomaly, but a much more extended investigation will be made
embracing many other acids as well as derivatives of amygdalin
to discover, if possible, something of the nature of this selective
affinity.

Macdonald Chemistry and Mining Building,
McGiLL University.

1378 MELDOLA AND HAY

CLIV. — 2 : 3 : b-Trinitvo-i-aminophenol and Derivatives.

By Raphael Meldola, F.R.S., and James Gordon Hay, A.I.C.

The acetyl derivative of the above compound has been fully described
in a series of papers published during the last few years (Trans., 1906,
89, 1935; 1907, 91, 1477; 1908, 93, 1659; 1909, 95, 1033), but
the corresponding trinitroaminophenol has only been incidentally
referred to {loc. cit., 91, 1477). As no trinitro-derivative of para-
aminophenol has hitherto been prepared, and as the acetyl derivative
has proved to be of especial interest on account of its reactivity, the
parent trinitro-compound seemed worthy of detailed study from several
points of view. In the first place, with respect to the possibility of
catenation products being formed from this compound by interaction with
amines in the same way as with the acetyl derivative, it may be pointed
out that, as no ring-formation would be possible in this case, the
products would be ortho-amino-derivatives of substituted diaryl- or
arylalkyl-amines :

OH OH

(^NnO, nhoR i^NOg

NOgi JNOo — '-> NO2I JNHR

NH2 NHg

Compounds of this type have hitherto been but little studied on
account of the difficulty of preparing them, and it was therefore hoped
that the new trinitroaminophenol would prove to be a convenient
material for synthesising them according to the above scheme. Our
experiments in this direction have, however, so far led to negative
results, and no definite compound has been obtained by the interaction
of trinitroaminophenol and amines under any conditions. The addition
of the amine to the alcoholic solution of the trinitro-compound leads in
the first place to the formation of a highly coloured (generally violet)
salt, which rapidly decomposes at the ordinary temperature. The
trinitro-compound is apparently completely decomposed by amines, with
the formation of i-esinous products. Although the study of these
products of decomposition has for the present been abandoned, the
research will be continued at some future time, as it is not improbable
that by modifying the conditions under which the reaction takes place
the required catenation products may be obtained.

The other dixection in which the trinitroaminophenol has been
studied is its behaviour on diazotisation, as the conditions are apparently
most favourable for the elimination of a nitro-group in accordance
with the rule which has been found to hold good in the case of the
dinitroanisidines. It will be seen in the experimental part of this

2 : 3:5-TRINlTRO-4-AMlNOPHKNOL AND DERIVATIVES. 1879

paper that the 3-nitio group in the trinitro-coinpound is not eliminated
on diazotisation, a fact of considerable interest when considered in
connexion with the results made known in a former paper (Trans.,
1907, 91, 1482). It was shown in this last paper that 2 : 3-dinitro-
4-aniinophenol does not lose the 3-nitro-group on diazotisation,
although the latter is in a favourable ortho-position with respect
to the aniiiio-group. From this fact it was concluded that it is
the methoxy-group which is the "loosening" substituent in this
and analogous cases, since the corresponding dinitroanisidiue
readily parts with the 3-nitro-group on diazotisation [loc. cit.,
p. 1484). This conclusion receives confirmation from the fact made
known in the present paper that 2 ; 3 : 5-trinitro-4-aminophenol also
retains the 3-nitro-group on diazotisation, since in this case the amino-
group (and therefore the diazoniuui group) is ortho with respect to
two nitro-groups. The corresponding trinitro-^;-anisidine has not been
obtained by us, although attempts have been made to prepare this
compound by the direct methylation of the silver salt of the trinitro-
acetylamiuoplienol (Trans., 1906, 89, 1937), and by the extreme
nitration of acotO'/janisidide. In the mean time a trinitroanisidine
of the required constitution appears to have been obtained in small
quantity by Reverdin by the extreme nitration of benzo-p-anisidide in
acetic anhydride solution {Arch. Sci. phys. nat , 1909, 27, 395).

The process originally described for the preparation of trinitro-
acetyl-j9-aminophenol (Trans., 1906, 89, 1936) has in the course of
our work been considerably improved, and we are now enabled to give
the details of the method finally adopted. In the earlier process the
diacetyl derivative of ;;-aminophenol was nitrated so as to furnish as
the first product the mononitro-compound of Hahle, and this by further
nitration was converted into the triuitroacetylaminophenol. In a
subsequent communication we pointed out that if the mononitro-
compound is partially hydrolysed so as to convert it into the 3-nitro-
4-acetylaminophenol, and the latter nitrated under regulated conditions,
2 : 3-dinitro-4-acetylamiuophenol is formed (Trans., 1907, 91, 1481).
In this last paper it was also stated that by extreme niti-ation the
mononitroacetylaminophenol is converted into the 2:3: 5-trinitro-
compound. The formation of the latter from 2 : 3-dinitro-4-acetyl-
aminophenol as well as from 3 : 5-dinitro-4-acetylaminopheuol (Trans.,
1906, 89, 1936) thus furnishes an additional proof of the constitution
which we originally assigned to this compound :

OH OH OH

/ \ / \NO / \NO

NO^l^^NO^ ^ NO^I^^NO^ ^ 'n^^NO^

NHAc NHAc NHAc

1380 MELDOLA AND HAY:

From these results it appears, also, that the course of nitration is
different, according as the mono- or the di-acetyl derivative of the mono-
nitro-compound is used as the initial stage, although the final product
is the same in both cases. The orienting influence of the Oacetyl
group thus determines the entry of the second nitro-group into
position 5, leaving only position 2 (or 6) for the third nitro-group.
The hydroxyl group, on the other hand, sends the second nitro-group
into position 2, leaving positions 5 and 6 for the third nitro-group,
which in fact enters position 5.

Experimental.
Preparation and Properties of Trinitroacetylaminophenol.

3-Nitro-4-acetylaminophenol is prepared by hydrolysing the diacetyl
derivative in the way previously described (Trans., 1907, 91, 1481,
footnote). The success of this operation depends on the rapidity with
which the hydrolysis is effected, and the use of just sufficient alkali to
bring about solution at the ordinary temperature. If an excess of
alkali is present, or if the solution when once formed is not imme-
diately acidified, there is much loss of material, owing to the decom-
posing action of the alkali. The 3-nitroacetylamino-compound, after
precipitation, is collected, washed with water, dried, and further
nitrated by dissolution in fuming nitric acid (D 1'5). One hundred c.c.
of acid will nitrate 30 grams of the mononitro-compound, the latter
being gradually stirred into the acid kept cool in melting ice. When
all the substance has been dissolved in the acid, the solution is at once
poured on to ice, and the trinitro-compound collected as soon as it has
separated. As this last compound is decomposed on long standing in
presence of dilute nitric acid, it is advisable to collect the precipitate
and wash it free from acid with as little delay as possible. Owing to
the solubility of the trinitro-compound in water, the quantity of ice
used for precipitation must also be limited to a minimum, or con-
siderable loss of material is incurred. The best solvent for jjurifyiog
the crude product is acetic acid, one crystallisation being generally
sufficient to give a pure compound if the above method of preparation
is followed.

Some of the general properties of 2:3 :5-trinitro-4-acetylaminophenol
have been described in former papers. The extreme reactivity of the
compound renders it unsafe to dry it in contact with organic matter,
such as filter paper. If dried in the water-oven on a paper filter,
deflagration takes place, although it may be safely dried in contact
with glass or porcelain. The extreme readiness with which the 3-nitro-
group is eliminated renders it impossible to prepare salts by combining
the compound with strong bases, as the latter cause complete decom-

2 :3: 5-TRIN1TRO-4-AMINOPHENOL AND DERIVATIVES, 1881

position. Attempts to replace the mobile nitro-group by methoxy- or
ethoxy-groups by iuteractioii with sodium meLhoxide or ethoxide gave
only resinous products. The extremely acid character of the compound
enables it to decompose metallic .«alts containing weaker acid radicles,
and this property has enabled us to isolate the potassium and sodium
salts. The former was prepared by dissolving the trinitro-compound
in a warm solution of potassium cyanide or potassium acetate ; the
salt separates out on cooling in splendid scarlet needles, which are very
soluble in cold water, but which, by rapid washing, can be freed from
mother-liquor. The .salt was dried at the ordinary temperature in a
desiccator, as it deflagrates when heated in the water-oven :

0-0316 gave 00082 K2SO4. K=ll-64.

CgHjOyNJvjH.p requires K = 11 -43 per cent.

The water of crystalli-sation could not be determined directly
by drying for the reason above stated. The sodium salt was not
obtained in sufficient quantity for analysis, as its solubility is
greater than that of the potassium salt, and it could not be purified by
washing. In appearance it resembles the potassium salt. This method
of obtaining salts of the trinitro-compound appears to be generally
applicable, and the research is being continued in this direction.

Preparation and Properties of Trinitroaminophenol.

The acetyl derivative cannot be hydrolysed by alkali?, owing to its
instability in presence of such reagents. The early attempts to
hydrolyse by means of sulphuric acid also failed, as the special
properties of the compound were not at the time sufficiently familiar
(Trans., 1906, 89, 1937). We have now found that the acetyl group
can be completely removed by sulphuric acid and without any decom-
position of the trinitroamino-compound if the following method is
closely adhered to.

The acetyl derivative is dissolved by stirring in an excess of con-
centrated sulphuric acid at the ordinai^y temperature of the laboratory.
The vessel containing the solution is then plunged into a bath of
boiling water for a few minutes and immediately withdrawn. The
course of the hydrolysis must be followed by rapid tests, a drop of the
solution being withdrawn on a glass rod at short intervals and diluted
with water on a watch-glass. When hydrolysis is complete, a scarlet,
crystalline precipitate is formed, and the sulphuric acid solution must
be cooled at once by immersion in cold water, or the hydrolysis proceeds
too far and decomposition takes place. A brownish tinge shown by
the precipitate indicates that the action of the sulphuric acid has been
too prolonged, as the pure compound is bright red. The whole operation
takes but a few minutes, and its success depends upon arresting the

1382 MELDOLA AND HAY :

action of the acid at the critical stage. When the latter point has
been reached and the solution cooled, the tvinitroamino-compound is
precipitated by pouring the solution on to ice. The red, crystalline
deposit can be collected and washed with water until free from acid.
It cannot be dried at 100° without decomposition. It can be crystal-
lised in small batches from acetic acid, from which it separates in deep
red needles having a decomposing point of about 145° :

0-0671 gave 12-65 c.c. N., (moist) at 95° and 767 mm. N = 22-84.
CgH^OyN^ requires N = 22-90 per cent.

The compound is but feebly basic, the sulphate being completely
dissociated by water. The salts formed with ammonia, alkyl- and
aryl-amines, alkaline hydroxides, etc., are of an intense violet colour,
but are so unstable that they undergo immediate decomposition.

Diazotisation of the Trinitroaminophenol.

The compound does not diazotise satisfactorily in acetic acid solu-
tion, the amino-group being no doubt " protected " by the nitro-
groups on either side. In order to effect diazotisation, the substance is
dissolved at the ordinary temperatui'e in concentrated sulphuric acid,
the solution diluted with a little water, and, when cold, an excess of
solid sodium nitrite stirred in in small portions. The course of the
diazotisation can be followed by mixing a drop of the solution with
water on a watch-glass ; the diazouium salt is decomposed by water
with the precipitation of a bright yellow diazo-oxide (quinonediazide),
so that the appearance of a yellow instead of a red precipitate on
dilution indicates the completion of the reaction.

2:3: b-Trinitrophenol.

The solution of the diazonium sulphate prepared as above under-
goes the usual " diazo-decompositions " with various reagents. On
boiling with excess of absolute alcohol as long as nitrogen is evolved,
evaporating the solvent, and diluting with water, trinitrophenol
crystallises out in ochreous needles. This compound, which is of
interest as being an isomeride of picric acid, has been brieily referred
to in a recent note (/. Soc. Dyers, 1909, 25, 12). It is slightly
soluble in boiling water, from which it separates in yellow needles,
melting at 119 — 120°, and becoming ochreous and opaque on drying
at 100^. It is readily soluble in alcohol, acetic acid, or benzene :

0-0852 gave 13-35 c.c. Ng (moist) at 17° and 764 mm. N = 18-24.
CgH-^yNg requires N = 18-34 per cent.

This trinitrophenol dyes silk and wool with a more orange shade
than picric acid. The hydroxyl group is so effectively protected that

2 : 3 :5-TRINlTRO-4-AMINOPHENOL AND DERIVATIVES. 1383

the compound could not be satisfactorily methylated or acetylated by
any of the ordinary methods. On dissolving in hot potassium carbonate
solution, a potassium salt separates out on cooling in red needles,
which contain no water of crystallisation :

Oi672 gave 0-0o54 KgSO^. K = 14-81.

CijH^O-NgK requires K = 14*66 per cent.

Other salts were prepared and examined qualitatively. When
dry, they deflagrate on heating, and are not at all comparable in
explosive power with the picrates. The solutions of the trinitrophenol
are much more highly coloured than the solid compound, a property
which, taken in connexion with the deep red colour of the salts,
suggests the usual zsonitro-tautomerism :

OH O

f \N0.2 _ f \:N02H(K, etc.)

NOgl /NO,, — NO^i JnOo

The trinitrophenol appeaxs to form a molecular compound with
naphthalene, which crystallises from alcohol in orange needles melting
at 100 — 101°. This compound is, however, much less stable than the
cori-esponding picrate, and the successive analyses following the
crystallisations indicated that dissociation takes place in alcoholic
solution.

From the foregoing results, it follows that there is no loss of a
nitro-group on diazotisation.

2:3: 5-Trinitroquinonediazide,

O ^ P

^NnO '^^NOo

NO2I JnoJ or NO._j' Jn02-

N,

^2

The diazonium sulphate prepared as described is immediately
decomposed on dilution with water, with the formation of a quinone-
diazide, which separates as a dense, yellow, micro-crystalline powder.
After being washed free from acid, the compound, although highly
explosive, can be safely dried in the water-oven. It has been found
very difficult to obtain the substance perfectly pure, as it is decom-
posed by most solvents, and tends to retain those which do not inter-
act with it chemically. The analytical results are, however, perfectly
definite in establishing the fact that no loss of a nitro-group occurs on
the transformation of the diazonium salt into the quinonediazide. The
latter is, in fact, unchanged by a solution of sodium acetate at the
ordinary temperature, although complete decomposition with the

1384. MELDOLA AND HAY :

formation of resiuous products is caused by the action of solutions of
alkalis or of alkaline carbonates. The compound can be crystallised
from boiling glacial acetic acid, provided the quantity is limited to
about half a gram. Boiling with this solvent causes some amount of
decomposition, as shown by the evolution of nitrous fumes, but the
loss is not serious if the scale of working is not too large. From the
hot saturated solution, the compound separates on cooling in dense,
ochreous prisms, the decomposing point of which was not determined on
account of the highly explosive character of the substance. Analysis
indicates that all the uitro-groups are retained :

0-0574 gave 13-05 c.c. N.^ (moist) at 13° and 7G5 mm. N = 26-98.
00574 „ 13-23 „ N2 „ „ 14° „ 764-3 mm. N = 27-25.
C^HOyNj requires N = 27*45 per cent.

This quinonediazide couples with ^-naphthol with extreme diffi-
culty, a property which is probably due to the protective action of
the 3- and 5-nitro-groups on the intermediate diazo-group. In the
presence of pyridine or an alkali, an azo-compound is formed, but there
is also further decomposition, due to the elimination of one of the
nitro-groups, the mobility of which is increased by the proximity of
the azo-naphthol complex. The azo-compound thus formed appears to
be a mixture of extremely insoluble products, which will require
further study before any definite conclusion concerning their nature
can be drawn.

The 3-nitro-group in the quinonediazide being in a favourable
position for displacement, attempts were made to arrive at definite
products by the substitution of other radicles for this group. Boiling
with .sodium acetate solution or with absolute alcohol brings about
definite decomposition, the latter in a quite unexpected way.

Dinitrohydroxyquinonediazide,
OH O

NO I 1*0 ^ °^ NO I Ioh" (^^ ^^^ corresponding cross-linking).

K K

The trinitro- compound dissolves in a strong boiling solution of
sodium acetate without any considerable evolution of nitrogen, and,
on cooling, a dense, orange, crystalline sodium salt separates. The
latter was collected, washed, redissolved in a small quantity of hot
water, and acidified with hydrochloric acid. Large, golden scales
separated on cooling, and these had all the properties of a quinone-
diazide, being highly explosive and coupling readily with y3-naphthol

2:3: 5-TRINITRO-4i-AMINOPHENOL AND DERIVATIVES. 1385

iu presence of alkali. Fi'om this result it appears that the S-nitro-
group is more readily removed than the diazo-group :

0-0614 gave 13-05 c.c. N2 (moist) at 18° and 767'1 ram. N = 24-70.
Cj5H20^N4 requires N = 24-78 per cent.

The compound may have either of the above formulse. Although
the ortho-quiuonediazide must be the first product resulting from the
displacement of the 3-nitro-group, it may easily undergo isomeric
transformation into the para-compound if the latter configuration is
the more stable. In view of the explosive character of the compound,
we are inclined to believe that it possesses the para-constitution, as
the ortho-quinonediazides are not, as a rule, so highly explosive.
It is, however, impossible at present to decide conclusively between
these formulae.

The quinonediazide in a pasty and moist condition combines with
/?-naphthol dissolved in sodium hydroxide, giving a highly-coloured
and dense, ciystalline deposit of a sodium salt having a bronzy lustre.
This salt can be collected and washed with a dilute solution of sodium
hydroxide until free from excess of naphthol. The azo-compound,
liberated by hydrochloric acid from the sodium salt, dissolves very
sparingly in boiling glacial acetic acid, from which it separates on
cooling in dull red needles, which begin to blacken about 240', but do
not melt at 320°. The azo-compound is phenolic in character, dis-
solving in aqueous ammonia or very dilute sodium hydroxide with an
indigo-blue colour, which changes to red on adding more sodium
hydroxide. This colour change most probably indicates the formation
of a disodium salt from a mono-sodium salt, as there are two hydroxyl
groups in the molecule, and it seems unnecessary in such a case to
introduce any hypothesis of structural change on the chemical evidence
only. From its mode of formation, the compound must be an azo-
naphthol derivative of 2 : 5-dinitroi esorcinol :

OH

Ano,

NO2I J OH

0-070 gave 8-95 c.c. Ng (moist) at 13° and 7597 mm. N = 15-l.
CjgHjoO-N^ requires N= 15-14 per cent.

Concentrated sulphuric acid dissolves the compound with a reddish-
violet colour, which becomes redder, and finally gives an orange,
gelatinous precipitate on dilution with water. It is probable that
this same azo-compound is among the products of the action of the
trinitroquinonediazide on /3-naphthol in piesence of alkali.

The decomposition of the trinitroquinonediazide by boiling absolute
alcohol leads to the formation of a compound the analysis of which

VOL. XCV. 4 X

1386 FINDLAY AND HICKMAXS : THE PARTIAL

indicates that a nitro-group is replaced by the ethoxy-gi^oup. The
study of this reaction is being continued.

The cost of this research has been partly met by a grant from the
Government Grant Fund of the Royal Society, a source of assistance
which we have much pleasure in acknowledging.

FiNSBFRY Technical Collegs.

CLV. — The Partial Racemisni of Meidliyl v-Mandelate.

By Alexander Findlay and Evelyn Marion Hickmans, M.Sc.

It has already been shown (Trans., 1907, 91, 905) fi-om a study of the
freezing-point curves of the ^-menthyl ester of the mandelic acids that
^raenthyl r-mandelate exists as a definite compound with the melting
point 83"7°. It was of importance, therefore, to investigate the
stability of the compound at lower temperatures, in order to ascertain
whether the transition point below which the partial racemate would
be unstable is sufficiently accessible to allow of the resolution of
r-mandelic acid by crystallisation of the ^-menthyl ester.

The experiments of A. McKenzie (Trans., 1904, 85, 1255) indicated
that the partial racemate is stable also at the ordinary temperature,
but nothing was known as to how far the transition point might lie
below this. For the investigation of this point, experiments based on
fractional crystallisation, although frequently employed in other cases,
are very unsuitable, owing to the possible occurrence of supersatura-
tion, difference in velocity of crystallisation, etc. These factors may
complicate, and apparently in some cases have complicated, the problem
,and led to false conclusions.*

* In this connexion, reference may be made to a paper recently published by
Professor Kipping (Trans., 1909, 95, 408), in which he points out that whereas, for
example, c^-hydrindamine r-mandelatc can be resolved by crystallisation from
aqueous solution, the rfZ-hydrindamiue rf-mandelate could not be so resolved. This
behaviour is considered as indicating the existence of partially racemic molecules in
solution. Although the writer is also of opinion that racemic and partially racemic
molecules can exist in the liquid state and in solution (compare Trans. Faraday
Soc, 1907, 3, Part 2), he does not consider that this is of particular importance for the
(pestion of the resolution of a racemic compound by crystallisation. What is <-f
importance is not what compounds exist in solution, but what solid substances can
exist in equilibrium with the solution. Although, no doubt, the substances clAlB
and lAdB (in the nomenclature of Professor Kipping) have the same solubility, the
partially racemic compounds dMB + dMB and dldB + lAdB are two distinct com-
pounds with their own solubility and stability conditions, including transition

RACEMISM OF MENTHYL R-MANDELATE. 1387

The determination of solubility with the partially I'aceraic material
alone as solid phase, and again with the partially racemic material
along with one of the optical antipodes as solid phases (equilibrators),
gives a simple and sure method of attacking the problem (Roozeboom,
Zeitsch. physikal. Chem., 189D, 28, 494). In this way one learns the
conditions under which the partial racemate is stable, and resolution
into the optical antipodes therefore impossible ; and the conditions
under which the resolution can be etl'ected.

Solubility determinations have been carried out by Ladenburg and
Doctor in the case of the strychnine tartrates {Ber., 1899, 32, 50),
whereby they showed that strychnine ^'-tartrate exhibits a transition
point at 30°, below which it is stable, but above which it breaks up
into the strychnine salts of the optically active forms. Resolution
therefore is possible only at temperatures abos'e the transition point.

Similarly, r-tetrahydroquinaldine hydrogen tartrate exhibits a
transition point at 59°, and i,s stable above that temperature (Laden-
burg and Herrmann, Ber., 1908, 41, 966. A summary of the work on
partial racemism is given in Anmden, 1909, 364, 227).

The method pursued by Ladenburg and Doctor in the former of the
two cases mentioned was to determine the solubility curves of
strychnine r-tartrate, strychnine (/-tartrate, and strychnine Z-tartrate
separately, the transition point being indicated by a break in the
curve. The picture of the relationships obtained in this way is, how-
ever, incomplete, and it is better to determine a series of isothermal
solubility curves with, in the first place, the partial racemate, and each
of the optical antipodes as single solid phases ; and, in the second place,
with the racemate together with each of the optical antipodes
separately as solid phases. This method of investigation has been of
the greatest value in the case of ordinary double salts, and it is the
method which we have employed in the case of the menthyl mande-
lates. The results obtained are all the moi'e of interest on account of
the fact that they constitute the first experimental values of the kind
for partially racemic substances.

temperature. Although, therefore, the former partial racemate may be unstable
under the conditions of crystallisation employed by Professor Kipping, it does not
follow that the latter partial racemate should also be so. Resolution, therefore,
might be effected in the former but not in the latter case. Such resolution, however,
would no doubt be effected by crystallisation at a suitable temperature, at which the
latter partial racemate is also unstable. The temperature above or below which this
instaliility occurs (the transition temperature) can, of course, be determined only by
experiment, and it is greatly to be desired that this be done, most simply by the
solubility method, as described in the present paper. The method of fractional
crystallisation, even when the temperature is regulated, is not so suitable, and gives
much less information. The temperature conditions, moreover, do not appear to
have received sufficient consideration by Professor Kipping. — A. F.

4x2

1388

FINDLAY AXD HICKMANS : THE PARTIAL

EXPKKI.MEXTAL.

The esters employed were prepared as described in our previous
paper (loc.icit.). The specific rotations of the esters in alcoholic solu-
tion were :

Z-Menthyl cZ-mandelate, [a],'/'' - 9-45°.
^-Menthyl Z-mandelate, [ a]i;' - 140-92°.
MMenthyl r-man delate, [a]lj'^ - 75-03°.
The solubility was determined by shaking a quantity of the solvent
with excess of the particular solid or solids until saturation occurred.

0-Z 0-4 0-6 0-8 1-0 1-2 1-4
Grams of l-menthyl d-mandelatc.

A certain quantity ''of the solution was removed by means of a
pipette furnished with a small filter, and weighed. It was then
evaporated to di'yness on the water-bath, and the total amount of
dissolved ester thus obtained. Where one was not dealing with a
single substance, the composition of the solution expressed in
terms of the menthyl ester of tlie d- and ^-antipodes was determined
polarimetrically.

In the case of the solubility determinations at 0°, however, the
5<jlution was prepared at the ordinary temperature, placed along with

RACEMISM OF MENTHYL K-MANDELATE. 1389

a quantity of the appropriate solid in melting ice, and shaken fre-
quently. These experiments were repeated several times until
concordant values were obtained.

The determinations were carried out at the temperatures 35°, 25°>
and 10°, using SO per cent, alcohol (by volume: df'' = 0'85n) as
solvent, and at 0°, using absolute alcohol as solvent. The results
obtained are summarised in the following tables, and are represented
graphically in the figure.

In the following tables, D represents ^-menthyl c^mandelate ;
L, ^-menthyl ^-mandelate ; and B, ^-menthyl r-mandelate. In almost
all cases the values are the mean of two sufficiently concordant
determinations.

Solubilities at 35°.

Solid phases. D. L. R. D + R. L + E.

Total solid (iu grams) iii 10

grams of solvent 1-08 3-19 1-60 1-89 3-43

Weight of Z iu 10 grams

of solvent — 3-19 0-80 0544 2-83

Weight of Z> iu 10 grams

ofsolvent 1-Q8 — 0-80 ' 1-350 0-60

Solubilities at 25°.

Solid phases. D. L. R. D + E. L + R.

Total solid (iu grams) in 10

grams of solvent 0 595 1-64 0-896 1 •203 1-458

Weight of L in 10 grams

ofsolvent — 1-64 0-448 0-321 1-192

Weight of R iu 10 grams

of.solvent 0-595 — 0-448 0-882 0-267

Solubilities at 10°.

Solid phases. D. L. R. D + R. L + R.

Total solid (in grams) in 10

grams of solvent 0-287 0 595 0-369 0-404 0-593

Weight of L in 10 grams

ofsolvent — 0-595 0-184 0-113 0-505

Weight of D iu 10 grams

ofsolvent 0-287 — 0-184 0-291 0-088

Solubilities at 0° {in absolute alcohol).

Solid phases. B. L. R. D + R. L + R.
Total solid (in grams) in 10

grams of solvent 1-06 1-93 1-25 1-45 1-57

Weight of L in 10 grams

ofsolvent — 1-93 0 625 0-535 1-03

Weight of D in 10 grams

ofsolvent I'Ob — 0625 0-915 0-54

1390 FINDLAY A\D HICKMAN'S : THE PARTIAL

I. Sohibilities at 35°.

A. Solid phase : L.

(1). Solution, 6-7599 ; ester, 1-6031.
(2). ,, 4-1783; ,, 1-0085.

B. Solid phase : D.

Solution, 8-3763 ; ester 0-8183

C. Solid phase : H.

(1). Solution, S-5414 ; ester, ri67f..
(2). „ 8-47-20; ,, 1-184-2.

D. Solid phases : L + R.

(1). Solution, S-740S ; ester, 2-2449.
(2). ,, 8-7600; „ '2-2265.

Rotation: (1). c = 2-6995. a^^« -6-32% [a]i^-»-6 - 117-06^
(2). c=3-0105. o^-i-a -7-14% [o]J^-a -118-76

E. Solid phases : D + E.

(1). Solution, 8-4957 ; ester, 1-3319.
(2). „ 8-56S0; ,, 1-3840.

Rotation: (1), c=:3-9555. o» - 3-74% [a];^^ - 47 27°.
'2), c = 4-0385. a» -3-Sr, [a]''^ -47-17°.

II. Solubilities at 25°.

A. Solid phase : L.

(1). Solution, 8-5947 ; ester, 1-2219.
(2). ,, 8-7410; ,, 1-2182.

i'. Solid phase : D.

(1). Solution, 8-5006 ; ester, 0-4739.
(2). ,, 8-4645; „ 0-4799.

C. Solid phase : E.

(1). Solution, 8-5344 ; ester, 0-6997.
(2). ,, 8-5908 ; ,, 0-7163.

Z>. Solid phases : L + ll.

(1). Solution, 8 '5757 ; ester, 1-0865.
(2). „ 7-8732; „ 1-0068.

Rotation: (1). c = 2-8095. a\* -6'45°, [o]^* -114-80°
(2). c = 2-1055. a''« -5-01°, [a]n-s -118-9°.

E. Solid phases: D + IL

Solution, 8-5476 ; ester, 0-9181.

Rotation: c = 2-7435. a|f -2-45°, [a^^ -44-65°.

RACEMISM OF MEXTHYL U-MANDELATE. 1391

III. Solubilities at 10*^.

A. Soli. I phase: L.

(1). Solution, 8-OS87 ; ester, 0-4802.
(2). ,, 8 5310 ; „ 0-4807.

B. Solid phase : D.

(1). Solution, 8-5732 ; ester, 0"2404.
(2). ,, 8-5878 ; ,, 0-2396.

<7. Solid phase : R.

(1). Solution, 8 4464 ; ester, 0-2960.
(2). ,, 8-5750; ,, 0-310-2.

D. Solid phases : L + R.

(1). Solution, 8-6417; ester, 0-4781.
(2). ,, 8-4306; ,, 0-4774.

Rotation: (1). c = 2"2585. a'/^ - 5-50°, [a];,^-'' - 1-21 -76°.
(2). c = 2-2185. a^-*" -5-36°, [a]f^ -120-8°.

E. Solid leases : D + R.

(1). Solution, 8-6024 ; ester, 0-3300.
(2). ,, 8-5986 ; ,, 0-3374.

Rotation: (1). c = l-5995. a^;' - 1-50°, [a]=o - 46-88°,
(2). <;=l-6300. oi'-» -1-45°, [a]"-* -44-49°.

IV. Solubilities at 0*=.

A. Solid phase : L.

(1). Solution, 7-2929 ; ester, 1-1961.
(2), ,, 8-1149; ,, 1-2956.

B. Solid phase : D.

(1). Solution, 5-4192 ; ester, 0-5144.
(2). ,, 4-7118; ,, 0-4622.

C. Solid phase : R.

(1). Solution, 7-2976 ; ester, 0-8273.
(2). „ 4-6545 ; ,, 0-5072.

D. Solid phases: L + R.

(1). Solution, 8-1281 ; ester, 0 0701.
(2). „ 6-3897 ; ,, 0-8927.

Rotation: (1). c = 3"2BId. a]* -6-14°, [a]'^^ -95-00°.
(2). 0 = 4-4025. aJ^^-3 -8-53°, [o]»-5 -96-87°.

B. Solid phases -.D + R.

(1). Solution, 4 -9148 ; ester, 0-6735.
(2). ,, 7-9437; ,, 0-9271.

Rotation: (1). f = 3-2825. a^^ -3-79°, [o]J/ -57-73°.
(2). 0 = 3-4015. oj^-i-2 -3-95°, [a])|-»-2 -58-06°.

On examining the solubility isothermals as shown in the figure,
it -will be seen that each isothermal consists of three parts, the inter-

1392 THE PARTIAL RACEMISM OF MENTHYL R-MANDELATE.

mediate curve representing the composition of solutions in equilibrium
with the partial racemate as solid phase. The eilistence of this inter-
mediate curve therefore indicates that at all temperatures down to 0°
the partial racemate is stable. It will therefore not be possible at
temperatures above 0° to resolve r-maudelic acid by simple crystal-
lisation of its Zmenthyl ester.

Crystallisation Experiments. — As the determination of solubility at
temperatures below 0° is troublesome, we have sought to ascertain
whether the transition point was nearly attained by carrying out a
crystallisation experiment at about - 15°. A solution of the partially
racemic ester in absolute alcohol was prepared at the ordinary tempera-
ture, and placed in a bath at about - 15°. After crystallisation of
part of the dissolved solid had occurred, the mother liquor was drawn
oJEf, and the .separated crystals were examined under the microscope.
Only needle-shaped crystals were observed, and these were found to
have a rotation [a]!;' - 76*4° (Z-menthyl r-mandelate has [a]^"^ - 75-03°).
If resolution had taken place, it was to be presumed that the less
soluble /-menthyl (i-mandelate would have separated out, and the
mother liquor would therefore be relatively rich in ^menthyl
Z-mandelate. This apparently was not the case, for on evaporating
the mother liquor to dryness and then determining the activity of
the residue, the values found were [a]}j*^ -74-11°, [a]15 - 70-4°, and
\(jV^ -71-41°. It appears thei^efore probable that even down to a
temperature of - 15° the partial racemate is still stable, and resolution
by crystallisation therefore impossible.

Chemical Depap.tmext,

Ukiversity of Birmingham.

COLOUR AND CONSTITUTION OF AZO-COMPOUNDS. PAKT IV. 1393

CLVI. — The Colour aiud Constitution of Azo-Compounds.

Part IV.

By John Theodore Hewitt and Ferdinand Bernard Thole.

In the development of the industry of the azo-dyestuffs it has been
recognised for many years that an increased depth of tone, accompanied
by a shifting of absorption towards the red end of the spectrum, can
in many cases be conveniently effected by the substitution of con-
stituents containing a naphthalene nucleus for those of simple
benzenoid type, whilst a further change in the same direction may be
attained by increasing the number of azo-groups, provided that these
are arranged in a suitable manner. The present paper is concerned
with the second of these pi'oblems, and only benzenoid compounds
have been dealt with, but isomeric compounds of mixed type in which
naphthalene and benzene nuclei are both present, but their positions
in the chain have been interchanged, are under examination, and
it is hoped that the results obtained will be shortly ready for
publication.

One of the authors of the present communication, in conjunction
with H. V. Mitchell (Trans., 1907, 91, 1251) and J. J. Fox (ibid.,
1908, 93, 333), has already drawn attention to the manner in which
a decrease in the principal vibration frequency of an azo-compound
accompanies an increase in the length of chain of conjugated double
linkings, and it appeared not at all improbable that in the case of
non-sulphonated polyazo-compounds containing hydroxyl or alkylated
amino-groups as " auxochromes," considerable light might be thrown
on the connexion between the increased length of chain of azo-groups
and aromatic nuclei by a study of the substances themselves and their
salts with mineral acids.

A point arises as to the extent to which quinonoid structure is set
up on salt formation, for it is evident from a consideration of the
formulae that in the case of substances like benzeneazobenzeneazo-
phenol, the quinonoid configuration may confine itself either to the
phenolic nucleus when a salt is formed by addition of a mineral acid
(Formula II), or may extend further so as to embrace the second
nucleus (Formula III) :

(I.) CsHs'NIN-CeH.-NIN-CeH^-OH.

(II.) c,H5-n:n-OoH,-nh-n:c,h,:o<|.
(HI.) C6H,-nh-n:c6H4:n-n:CsH,:o<^.

VOL. XCV. 4 Y

1394 HEWITT AND THOLE: THE COLOUR AND

Slvould tho effect of salt formation be to produce a salt of type III,
it might be expected that treatment of the solution of benzeneazo-
beuzeneazophenol in concentrated sulphuric acid with nitric acid would
lead to production of a nitrated compound of the formula

NOa-CgH^-NIN-CeH^-NIN-CeH^-OH,
whilst if the quinonoid structure only extended as far as the first
benzene nucleus, either the middle benzene nucleus should undergo
substitution, or possibly, owing to the para-position being already
occupied, no definite result would be obtained. On carrying out
experiments on the lines indicated, no satisfactory product of nitration
could be isolated, so that one hesitates to draw any definite
conclusion.

Briefly, however, benzeneazobenzeneazodimethylaniline, itself a
compound crystallising in purplish leaflets, and giving orange solutions
in neutral solvents, yields a monohydrochloride the hydrochloric acid
solution of which is of an intense blue colour. With concentrated
sulphuric acid, a red solution is obtained, the substance evidently
behaving as a polyacid base, for on adding water the blue colour
is produced, whilst further dilution gives rise to an orange shade.
That the latter is due to hydrolytic dissociation is evident, addition of
ammonia producing no further colour change. The substance thus
appears to be a weaker base than dimethylaminoazobenzene, the
salts of which are stable with a relatively greater dilution of the
acid.

The solution of the corresponding benzeneazobenzeneazophenol in
concentrated sulphuric acid is purple ; possibly in this case only a
monacid salt is formed, for, as will be seen later, the basic properties
of this substance are very weak.

The polyacid salts of azo-compounds have already engaged the
attention of A. Korczyriski {Ber., 1908, 41, 4379), whilst more
recently Hantzsch [ibid., 1909, 42, 2131) has drawn particular
attention to the colour changes accompanying the conversion of
benzeneazodimethylaniline into its mono- and di-acid salts. To com-
pounds of the latter type Hantzsch assigns the general formula
Ar-Ng-CeH^-NRg^HX
HX
on account of the similarity of their absorption spectra to that
of solutions of azobenzene in concentrated mineral acids,

Benzeneazohenzeneazodimethylaniline,

C6H5-n:n-C6H4-n:n-C6H4-n(ch3)2.

To prepare this substance, 9'8 grams of finely powdered aminoazo-
benzene were mixed with 70 c.c. water and 19*5 c.c. concentrated

CONSTITUTION OF AZO-COMPOUNDS. PART IV. 1395

hydrochloric acid, a suspension of the hydrochloride being thereby
obtained. Under addition of crushed ice and external cooling
diazotisation was effected with 3'6 grams sodium nitrite in 20 c.c.
water, and the solution filtered into 6 grams of dimethylaniline
dissolved in 25 c.c. glacial acetic acid to which a little crushed ice had
been added. The excess of mineral acid was removed by adding
5 grams of crystallised sodium acetate, and after three hours the
precipitate was collected. Crystallisation from pyridine furnished
small purple crystals, melting constantly at 190° (uncorr.) :

0-1214 gave 0-3241 COg and 0-0640 H.p. C = 72-8; H = 5-9.

0-0638 „ 11-5 c.c. N2 at 20° and 763 mm. N = 21-2.

C20H19N5 requires C = 72-9 ; H = 5-8 ; N = 21 -3 per cent.

Hydrochloride, CgoHjgNjjHCl. — As previously mentioned, the base
dissolves in concentrated sulphuric acid with a red colour which
passes into blue on dilution, whilst with the most concentrated hydro-
chloric acid only blue solutions were obtained. In the latter, the
head of the band in the visible part of the spectrum corresponds with
an oscillation frequency of about 1760. The red sulphuric acid
solution evidently corresponds with the orange " azo-salt " of Hantzsch
{loc. cit.) in the case of dimethylaminoazobenzene, so that it would
appear that whilst the latter compound is sufficiently basic to give a
di-acid " azo-salt " with concentrated hydrochloric acid, the intro-
duction of a benzeneazo-group in place of hydrogen has considerably
weakened the basic properties. The isolation and analysis of the
hydrochloride being eminently desirable, 0'5 gram of the substance
was boiled with 20 c.c. of alcohol and 5 c.c. of hydrochloric acid, the
solution filtered, and slowly concentrated in a desiccator containing
sulphuric acid. The resulting crystals showed a fine metallic reflex :

0-1553 gave 0-0599 AgCl. CI = 9-5.

C20H20N5CI requires CI = 9-4 per cent. «

The salt gradually loses hydrogen chloride on keeping and falls
to a brown powder ; this behaviour is to be expected when one con-
siders the ease with which the salt is hydrolysed in aqueous solution.

An attempt to make a dibrominated derivative starting with the
dibromoaminoazobenzene (CgHgNg : Br : NHg : Br = 1 : 3 : 4 : 5) melting
at 168° (Berju, ^er., 1884, 17, 1403; Hewitt and Walker, Trans.,
1907, 91, 1138) failed, owing to inability to diazotise the amine,
even when treated in alcoholic suspension with concentrated sulphuric
acid and amyl nitrite and kept overnight. This observation is
thought to be worthy of record, since 2:4: 6-tribromoaniline, although
diflicult to diazotise, is attacked by nitrous acid. Although the hope
of examining such a negatively substituted derivative had to be
abandoned, a higher homologue has been prepared.

4 Y 2

1396 COLOUR AND CONSTITUTION OF AZO-COMPOUNDS. PART IV.

0-Tolueneazo-o-tolueneazodimethylaniline,
C^H^Me-NIN-CgHgMe-NrN-CeH^-NMea.

This substance was prepared from the aminoazotoluene described by
Nietzki {Ber., 1877, 10, 662). Instead of preparing it by the original
method of leading nitrous fumes into o-toluidine, a process was adopted
analogous to that usually employed in the preparation of aminoazo-
benzene, and the substance was obtained with constant melting point
without recrystallisation. The diazotisation of the aminoazo-compound
and coupling with dimethylaniline was effected in the same manner as
described for the lower homologue, except that a large bulk of water
has to be used for the solution of the tolueneazotolyldiazonium salt.
The resulting dimethylamino-compound was crystallised from benzene ;
it melts at 138° (uncorr.) :

0-1329 gave 0-3584 COg and 0-0806 H2O. C = 74-1 ; H = 6-6.

0-1204 „ 200 c.c. N.^ at 17° and 766 mm. N = 19-8.

a2H^3N5 requires 0 = 73-95; H = 6-44; N= 19-61 percent.

The solutions in sulphuric and hydrochloric acids show exactly the
same behaviour as those of the lower homologue.

Hydrochloride, CogHgjNjjHCl. — This salt was prepared in the same
way as used for benzeneazobenzeneazodimethylaniline hydrochloride :

0-1916 gave 00669 AgCl. Cl = 8-6.

CogHggNg.HCl requires 01 = 9-0 per cent.

Benzeiieazohenzeneazophenol, CgH^'NIN-OgH^'NIN'OgH^'OH. — This
compound, which has already been prepared by Oaro and Schraube
{Ber., 1877, 10, 2230), was obtained in the usual manner from
diazotised aminoazobenzene and phenol :

0-1328 gave 20-2 c.c. Nj at 16° and 776 mm. N= 18-4.
OjgHj^ON^ requires N= 18-5 per cent.

The azophenol dissolves in concentrated sulphuric acid with a purple
colour ; the head of the absorption band in the visible spectrum of such
a solution corresponds with an oscillation frequency of about 1860 ; the
sulphate has not been isolated. The solubility in concentrated hydro-
chloric acid is very slight and the solution has an orange tint, so that
it is possible that the salt may be largely hydrolysed even in presence
of large quantities of the acid.

Unfortunately the monohydrochloride could not be prepared by the
usual method of passing hydrogen chloride into a benzene solution of the
azophenol, since the latter is nearly insoluble in the cold hydrocarbon.
Hydrogen chloride was, therefore, led for several hours over a paste
of the azophenol with glacial acetic acid ; the mass was then trans-
ferred to porous earthenware and dried in an atmosphere of hydrogen

THE QUANTITATIVE DECOMPOSITION OF THE ANILIDES. 1897

chloride. The freshly prepared salt seems to have been formed by
absorption of two molecules of acid (compare Korczynski, loc. cit.) :
0-1522 gave 0-1085 AgCl. CI = 17-62.

C,8Hi^ON4,2HCl requires CI = 18-88 per cent.
CigHi.ON^HCl „ CI = 10-52
Hydrogen chloride is gradually lost on standing, salt which had
been kept for four days in a corked specimen tube containing only
14-33 per cent, of chlorine. It is evident that the second molecule is
rather loosely combined.

Acetyl Derivative.

Two grams of the azophenol were boiled for three hours with
30 grams of acetic anhydride. The solution was poured into hot
dilute alcohol and the precipitated acetyl derivative crystallised from
glacial acetic acid. Both before and after the latter operation, the
same melting point, 178° (uncorr.), was observed :

01433 gave 19-1 c.c. N2 at W and 775 mm. N= 16-2.
C2oHj6^2^4 requires N= 16'3 per cent.
East London College.

CLVII. — The Quantitative Decomposition of the
Anilides : a Study in Steric Injiuence.

By Oliver Charles Minty Davis.

The investigation here described was undertaken with the primary
object of measuring the quantitative effect of the orientation of a
compound on its chemical reactivity, and incidentally to notice the
influence of various substituent groups and elements on this reactivity.
There are at least three ways in which stereo-configuration may
influence a chemical reaction :

(1) When no side-reaction takes place the effect is to bring about
differences in the rate of reaction ; in very extreme cases no appreci-
able quantity of end product would be obtained within a reasonable
time, and such a slow reaction would be regarded for practical purposes
as not occurring at all.

(2) "When side-reactions are possible and the original main reaction
is very much retarded, obviously the chief end products would be
those due to one or more of these side-reactions. The quickest of the
possible reactions would in all cases be the one securing the most of
the initial substance, and thus producing the predominant end product.

1398 DAVIS: THE QUANTITATIVE

These original side-reactions might thus be unaltered, or even favoured
by the new stereo-configuration, and so the practical result would be
the formation of new end products.

(3) There is another possible way in which stereo-configuration
might exert an important influence essentially distinct from mere
retardation or acceleration of rate of reaction. This is the effect on
the chemical affinity of the substance. Little or no work has been
done in this field, for it is evident that measurements of rates of
reaction afford no satisfactory evidence in regard to affinity relation-
ship.

The only methods of investigating this effect on the chemical
affinity is the determination of the position of equilibrium, or the
measurement of the corresponding electromotive force.

The present paper contains the results of the kinetic measurements
of the anilides in the presence of a small excess of alkali. Here it
was found that the decomposition was practically quantitative.
Further work is being carried out in acid systems to determine the
static equilibria

Experimental.

The majority of the compounds used could not be obtained
commercially, and it was necessary to prepare and purify them.

The nitro-compounds were recrystallised from alcohol, but in the
other cases water proved the most suitable solvent ; the only liquid
member is formo-w-toluidide, which was obtained in a state of purity
by distillation in a vacuum.

The following analytical data were obtained for those compounds
which had not been previously prepared.

m-Chloroformanilide, m. p. 57 — 58°.

0-2650 gave 22-0 c.c. Ng (moist) at 21° and 740 mm. N = 9-2.
C-HgONCl requires N = 9"0 per cent.

nx-Chloropropionanilide, m. p. 88 — 89°.

0-2940 gave 20-0 c.c. N2 (moist) at 19° and 756 mm. ]Sr = 7'8.
C9H10ONCI requires N = 7'6 per cent.

■n-Butyro-o-toluidide, m. p. 79 — 80°.

0-233 gave 16-00 c.c. N^ (moist) at 15° and 762 mm. N = 8-0.
CjjHjjON requires N = 7-9 per cent.

n-Butyro--p-toluidide, m. p. 74 — 75°.

0-255 gave 18-00 c.c. Ng (moist) at 16° and 761 mm. N' = 8-2.
CjjHjgON requires N = 7-9 per cent.

DECOMPOSITION OF THE ANILIDES. 1399

Method of Experiment.

It was impossible to carry out the experiments at a low temperature
on account of the slight solubility of many of the members of
the series under examination. The following method was found to
give the most concordant results when several control experiments
were carried out ; hence it was adopted throughout.

A definite weight of the anilide (l/400th gram molecule) was care-
fully washed into a Jena-glass flask with 50 c.c. of distilled water.*
Twenty-five c.c. of iV/5-sodium hydroxide, free from carbonate, were
then added, and the flask fitted with a reflux condenser, the inner tube
of which was of Jena glass. The flask was then boiled over wire
gauze and a Bunsen flame. At the end of definite periods the boiling
was stopped, and the whole contents of the flask titrated with iV/10-
sulphuric acid, using phenolphthalein as indicator.

It was found necessary to make a con-ection for alkali dissolved
from the flasks by the boiling solutions. By allowing 01 c.c. of JV/IO-
alkali for each hour's boiling, this source of error is reduced to a
minimum. To avoid it entirely, for those experiments involving pro-
longed boiling, a flask made of fine silver was used ; the condenser was
also provided with a tube containing solid potassium hydroxide, to
prevent access of carbon dioxide.

Formula used to express Bate of Hydrolysis.

The results of the experiments demonstrated that the velocity of the
reaction is proportional to the concentration of the free alkali, as well
as to that of the undecomposed anilide present. Hence K is calculated
according to the bimolecular formula :

K= ^ log. ^(^:i^,

t{h-a) ^ b (a-x)
in which the time t is expressed in hours ; all concentrations are
expressed in gram-molecules per litre, and Napierian logarithms are
employed. The original concentration of the anilide is a, and that of
the alkali, b (always made twice as great).

X is the amount of anilide which has been decomposed up to
any given time t.

This formula does not strictly apply unless all the anilide is present
in solution from the commencement of the reaction. In all cases not
specially mentioned in the tables several minutes only were required
for complete solution.

* In experiments of short duration, the solution was raised to boiling point before
adding the standard alkali. Unless otherwise stated, the solution of anihde was
rapid and complete.

1400

DAVIS: THE QUANTITATIVE

Initial incomplete solution would tend to lower the value of the
earlier constants in each series, but would not so seriously affect
the later ones.

In the few cases in which a fraction of the anilide remained
undissolved throughout the duration of the experiment, the results
were, nevertheless, calculated according to the same formula.

General Conclusions.

Influence of the Methyl Group. — The stability of the anilides
increases with progressive introduction of methyl groups into the
acidic group, and is greater when the anilide is derived from an " iso "
acid.

This is well shown in the following table :

Time for
50 per cent.

Number of decomposition, K

Compound. measurements. in hours. (average).

*Formanilide 6 0-14 87-1

♦Acetanilide 11 379 .3-20

Propionanilide 12 6-3 1*93

Ti-Butyranilide 10 13-0 0-934

woBut3'rauilide 7 30*7 0-395

7i-Valeranilide 3 18 '5 0-656

tsoValeranilide 5 92-7 0-131

* Throughout the tables, an asterisk is placed against the names of all the
anilides the decomposition of which was actually followed up to more than 98 per
cent. The time for 50 per cent, decomposition is calculated from the constant.

In the case of the valeranilides solution was incomplete throughout ;
hence only a few experiments were performed.

Only two cases were examined in which the " imidic " hydrogen was
replaced by alkyl groups. Methylacetanilide is less resistant to alkalis
than acetanilide, whereas ethylacetanilide is far more resistant. The
greater instability of methylacetanilide is probably due to the fact
that it is the first member of a series, and hence apt to behave
anomalously.

Time for
50 per cent.
Number of decomposition, K

Compound. measurements. in hours. (average).

♦Acetanilide 11 3-79 320

♦Methylacetanilide 10 3-16 3-84

Ethylacetanilide 10 13-00 0-94

The effect of the methyl group when introduced into the benzene
nucleus may be very great, or almost negligible, according to the
position it occupies. In all cases where the ortho-position is concerned,
the result is a very great diminution in the velocity of hydrolysis.

DECOMPOSITION OF THE ANILIDES.

1401

The influence of the meta- and para-substituents is much less
noticeable, and is greatest in the case of the fonnotoluidides (where,
owing to short duration of experiments the errors are apt to be large),
and in those compounds where complete solution was not obtained
throughout the experiments.

Time for

50 per cent.

Number of

decomposition,

K

Compound.

measurements.

in hours.

(average).

*Forniaiiilide

6

8

0-36 1 ^13

87-1

*Formo-o-toluidide

33-9

*Formo-m-tohiidide

4

0-16 (a.2

74-6

*Formo-^-toluidide

4

0-14J S-^

82-9

"Acetanilide ...

11

3-79

3-20

Aceto-o-toluidide

11

17-16

0-709

*Aceto-w-toluidide

6

3-89

3-14

*Aceto-jo-toluidide

7

3-90

3-11

Propionanilide

12

6-29

1-93

Propio-o-toluidide

8

30-36

0-400

Propio-?rt-toluidide

7

6-42

1-89

Propio-j[;-toluidide

7

6-57

1-85

71- Butyranilide

10

13-02

0-934

9t-Butyro-o-toluidide ..

2

58-66

0-207

fji-Butyro-jo-toluidide ..

3

18-53

0-656

wo Butyranilide

7

30-68

0-395

isoButyro-o-toluidide ..

2

125-71

0 096

tisoButyro-7?i-toluidide .

2

41-90

0-290

tisoButyro-i^-tohiidide ..

2

44 01

0-276

t Sohition not quite complete.

Eff'ect of Chlorine.

In the ortho- and para-positions the influence of chlorine is very
slight, and may either increase or retard hydrolysis. The apparent
inhibitory action of chlorine in the para-position in acetanilide and
propionanilide is probably due to the fact that these compounds take
longer to dissolve than the ortho- and meta-isomerides.

Compound.

*Formanilide

*o-Cliloroformanilide ...
*»i-Chloroformanilide ...
*p-Chloroformanilide ...

Acetanilide ,

*o-Chloroacetanilide

*m-Chloroacetanilide ...

/>-Chloroacetanilide

Propionanilide

o-Chloropropionanilide.

m- Chloropropionanilide

p-Chloropropionanilide.

Number of
measurements.
6
3
3
3
11

12
4
4
4

Time for

50 per cent.

decomposition,

in hours.

K
(average).
87-1
91-9
87-1
88-4
3-20
3 10
3-31
3 07
1-93
2-07
2-07
1-52

1402 THE QUANTITATIVE DECOMPOSITION OF THE ANILIDES.

Effect of Bromine.

Only one series of bromine derivatives was examined, namely, the
bromoacetanilides. This substituent has very slight effect on the rate
of hydrolysis when in the ortho- and meta-positions. The apparent
diminution in the velocity of decomposition brought about by the
introduction of bromine in the para-position is probably due to the
fact that it dissolves less rapidly than its isomerides (compare
/>-chloroacetanilide and /)-chloropropionanilide).

Time for

50 per cent.

Number of

decomposition,

K

Compound.

measurements.

in hours.

(average)

^Acetanilide

11

3-79

3-20

o-Bromoacetanilide .

7

3-74

3-31

m-Bromoacetanilide .

7

3-70

3-28

y-Bromoacetaiiilide .

7

4-09

2-97

Effect of the Nitro-group.

The introduction of a nitro-group into the benzene nucleus has
invariably an accelerating effect on the velocity of decomposition.
With the formanilide derivatives the result is identical whether this
group occupies the ortho- or para-positions, but with acetanilide and
benzanilide derivatives the influence is greatest when the substituent
group occupies the ortho-position, and next in magnitude when the
para-position is concerned. In all cases the meta-substituent has an
intermediate effect.

Time for
50 per cent.
Number of decomposition, K

Compound. measurements. in hours. (average).

♦Formanilide 6 O'H 87-1

*o-Nitroformanilide ... Complete decomposition within 5 minutes.
*m-Nitroformanilide ... 3 O'lO 118-9

*p-Nitroformanilide ... Complete decomposition within 5 minutes.

*Acetanilide 11 379 3-20

*o-Nitroacetanilide 1 Within 5 minutes

TO-Nitroacetanilide ... 7 2*22 5-45

*p-Nitroacetanilide 1 "Within 5 minutes

Benzanilide Too insoluble lor experiment.

*o-Nitrobenzanilide ... 2 0-22 *55-3

VNitrobenzanilide ... 4 0-92 13-13

Effect of Methoxy- and Ethoxy -groups.

The introduction of these groups into the benzene nucleus has a
very similar effect in both cases. When substituted in the ortho-
position the result is to produce a considerable decrease in the
magnitude of the velocity constant, but the decrease is much smaller

ACYL DERIVATIVES OF ALDEHYDE-CYANOHYDRINS. 1403

than in the case of the methyl group. There is also a slight decrease
in the rate of decomposition when these groups occupy the meta-
position, but when in the para-position a slight increase in the
magnitude of the constant is observed in both cases.

Time for

50 per cent.

Number of

decomposition,

K.

Coiniiouiul.

measurements.

in hours.

(average).

*Acetaiiilide

11

3-79

3-20

*A(5eto-o-aiiisiclide .. ..

7

5-50

2-28

Aceto-??i-anisi(lidc

6

4-24

2-86

Aceto-;?-ani.sidide

6

3-57

;5-40

Aceto-o-phenetiilide ,.

7

5-33

2-34

Acc'to-?«-phenetidide .

6

4-19

2'90

Aceto-y-pheiietidide .

6

3-70

3-28

The result of this investigation is to show conclusively that the
main effect of the introduction of substituent elements or groups into
the anilide molecule is to bring about diiferences in the magnitude of
the constants expressing the velocity of hydrolysis.

The numerous prolonged experiments carried out with the aid of a
silver flask show that, so far as can be experimentally determined
under the conditions chosen, complete decomposition could be brought
about in all cases investigated. In eighteen instances the decomposi-
tion actually amounts to 100 per cent., and in those cases where this
degree of hydrolysis has not been attained, there is no indication of
an equilibrium, as the constants do not fall off perceptibly towards
the end.

Chemical Laboratory,

University of Bristol.

CLVIII. — Prejparation of the Acyl Derivatives of the
Aldehyde-cyanohydrins. Part I.

By Francis Francis and Oliver Charles Minty Davis.

One of the authors, whilst investigating some reactions of the aldehyde-
cyanohydrins, found that benzaldehyde readily gave a quantitative
yield of benzoylmandelonitrile when treated with benzoyl chloride in
the presence of an aqueous solution of potassium cyanide. As deriv-
atives of this type do not appear to have been previously described,
the reaction was investigated further, and it has been found that a
corresponding change takes place with other aromatic aldehydes ; only
a few experiments were made with those of the aliphatic series, but

1404 FRANCIS AND DAVIS: PREPARATION OF THE ACYL

here also the behaviour was similar. Sufficient data have been
collected to show that the decomposition may be generalised and
expressed as follows :

R-CHO + Ph-COCl + KCN _> R-CH(OBz)-CN + KCl.

Moreover, experiments carried out with the acid chlorides of anisic,
7H-nitrobenzoic, cinnamic, and phthalic acids, and also with ethyl chloro-
formate and benzenesulphonyl chloride, have shown that a general
method has been found for the formation of the acyl derivatives of the
aldehyde-cyanohydrins.

It seems probable that the first phase of the reaction consists in the
formation of cyanohydrins by the interaction of the aldehyde and
aqueous cyanide solution, and then, in the presence of the resulting
free alkali, these react in the ordinary manner with the acid chloride
to form acyl derivatives.

This view of the course of the reaction is borne out by the formation of
the benzoyl derivatives of benzaldehydecyanohydrin and anisaldehyde-
cyanohydrin by the interaction of benzoyl chloride and the correspond-
ing cyanohydrin in the presence of aqueous potassium hydroxide, the
resulting substances being identical with those prepared from the
aldehyde direct by means of benzoyl chloride and cyanide solution.

Preliminary experiments have shown that the method employed may
be of importance in the preparation of other types of derivatives, and
that, besides potassium cyanide, other hydrolysed salts may be utilised.
Investigations are now proceeding, and these, together with the
detailed description of some of the substances mentioned in this paper,
will be left for », further communication.

Experimental.
Preparation of Benzoyl Derivatives.

Benzoylmandelonitrile, CHPh(OBz)*C]Sr, — The calculated amounts of
benzaldehyde and benzoyl chloride are shaken with an aqueous solution
of potassium cyanide containing about 2 per cent, more than the
amount required for the reaction. If large amounts are taken it is
necessary to cool the flask in which the operation is carried out ; after
shaking vigorously for a few minutes the solid benzoyl derivative
separates out, and is obtained pure and in quantitative yield by
crystallisation from alcohol, from which it crystallises in well-formed
needles melting at 63 — 64°. The substance is soluble in the ordinary
organic solvents, and is not decomposed by prolonged boiling with
dilute hydrochloric acid :

0-2164 gave 0-5986 CO2 and 0-906 H2O. C = 75'44; H = 4-64.

0-216 „ 10-4 cc. Ng (moist) at 13° and 759 mm. N = 5-68.
C15H11O2N requires C = 75*94 ; H = 464 ; N - 5-90 per cent.

DERIVATIVES OF THE ALDEHYDE-CYANOHYDRINS. PART I. 1405

A molecular weight determination by the ebullioscopic method
using benzene as solvent gave the following result :

Substance. Solveut. E. M.W.

1-105 311 0-4° 238

C15H11O2N requires M.W. = 237.

The sub.stance obtained from the interaction of mandelonitrile and
benzoyl chloride in the presence of aqueous potassium hydroxide was
identical with the above ; it melted at 63° and an analysis gave
N = 5'94 per cent.

Benzoyl-'^-methoxymandelonitrile, OMe*C6H4'CH(OBz)*CN.

The method employed for the preparation of this derivative was,
using anisaldehyde in place of benzaldehyde, identical with that
previously described. The substance crystallises from alcohol in clear,
colourless plates melting at 66 — 67° :

0-1998 gave 0-5244 CO,, and 0-0894 H2O. 0 = 71-58; H = 4-97.

0-5002 ,, 22-4 c.c. n[, (moist) at 16°"'and 744 mm. N = 5-10.

0-2623 „ 0-2295 Agf. OMe = ll-55.
CioHjgOaN requires C = 71 -9 1 ; H = 486 ; N = 5-2 ; OMe = 11-61 percent.

A molecular weight determination by the ebullioscopic method,
using benzene as solvent, gave the following result :

Substance. Solvent. E. M.W,

1-1985 31-9 0-375° 267

CieHigOjN requires M.W. =267.

A compound identical with the above (melting at 67° and containing
5*32 per cent, of nitrogen) was obtained by the action of benzoyl
chloride on /j-anis^aldehyde-cyanohydrin in the presence of aqueous
potassium hydroxide.

Benzoyl-o-methoxymandelonitrile, OMe'CgH^(OBz)'CN.

A small yield of this derivative was obtained from o-methoxy-
benzaldehyde. On recrystallisation from alcohol it melted at 87 — 88°
0-4462 gave 20-2 c.c. Ng (moist) at 17° and 754 mm. N = 5-21.
CjgHj^Oa^ requires N = 5-2 per cent.

Benzoyl-T^-tolylglycollonitrile, CQH4Me*CH(0Bz)*CN.

A quantitative yield of this substance was obtained from ;>tolualde-
hyde. On recrystallisation from alcohol it melted at 55 — 56° :
0-4984 gave 24-2 c.c. N.^ (moist) at 16° and 741 mm. N = 5-53.
C^gHj302N requires N = 5-57 per cent.

1406 FRANCIS AND DAVIS: PREPARATION OF THE ACYL

Bemoylcuinylglycollonitrile, CHMe2'CgH4'CH(OBz)*CN.

This derivative, prepared from cumiualdehyde, crystallises from
alcohol in needles melting at 68 — 69° :

0-2239 gave 0-638 COg and 0-128 HgO. C = 77-71 ; H = 6-3.
0-3580 ,, 15-6 c.c. Ng (moist) at 16° and 750 mm. N = 5-00.
CisHivOgN requires C = 77-41 ; H = 6-09; N = 5-01 per cent.

a-Benzoyloxy-y-phenyli&ocrotononitrile, CB[PhICH'CH(OBz)'CN.

Prepared from cinnamaldehyde ; melts at 72 — 73° on crystallisation
from alcohol :

0-2271 gave 0-6520 CO2 and 0-108 H2O. C = 78-2 ; H = 5-2.
0-517 „ 24-4 c.c. N2 (moist) at 18° and 736 mm. N = 5-27.
Cj^HigOgN requires C = 77-6 ; H = 4-9 ; N = 5-3 per cent.

Benzoyloxyhomopiperonylonitrile, CH2l02^CgH3*CH(OBz)'CN.

In the case of piperonal the reaction led to the production of an
oily substance from which the above derivative, melting at 57°, was
isolated by washing with a small amount of ether and crystallisation
from alcohol :

0-452 gave 19-6 c.c. Ng (moist) at 20° and 766 mm. N = 5-0.
CjgHjjO^N requires N = 4-98 per cent.

Tp-Chlorohenzoylmandelonitrile, C6H4Cl*CH(OBz)*CN.

This derivative, prepared from ^-chlorobenzaldehyde, was isolated by
the method described in the previous case, and on crystallisation from
alcohol melted at 57 — 58° :

0-59 gave 26-1 c.c. N2 (moist) at 12° and 748 mm. N = 5-16.
Cj-Hj^^OgNCl requires N = 5-15 per cent.

Benzoyl- fi-naphthylglycollonitrile, CjqH-*CH(OBz)*CN.

When ^-naphthaldehyde was employed and the reaction carried out
as previously described, only a small quantity of a red insoluble
substance was obtained. On crystallisation from nitrobenzene it melts
at 239° and from the analysis appears to be similar to the other
derivatives of this class :

0-1 75 gave 0-506 CO2 and 0-067 B.f>. C = 78-86 ; H = 4-2.
C^gHjgOjN requires 0 = 79-4; H = 4-5 per cent.

DERIVATIVES OF THE ALDEHYDE-CYANOHYDRINS. PART I. 1407

Trichlorohenzoyllactonitrile, CCl3'CH(0Bz)'CN.

When chloral is dissolved in water containing the necessary amount
of potassium cyanide and treated with benzoyl chloride, a white,
semi-solid mass slowly separates ; on crystallisation from a mixture
of alcohol, water, and ether, a 50 per cent, yield of the derivative is
obtained. It is very soluble in the ordinary organic solvents, insoluble
in water, and melts at 40 — 41° :

0-564 gave 24-8 c.c. N^ (moist) at 18° and 759 mm. N = 5-07.

0-608 „ 0-93 AgCl." CI = 37-8.

CioHgOaNClg requires N = 5-02 ; CI = 38-24 per cent.

Preparation of Anisoyl Derivatives.
p-Anisoylmandelonitrile, CHPh(0"C0*CgH4-0Me)'CN.

Anisoyl chloride can replace benzoyl chloride and the reaction is
carried out in a similar luanner to that previously described. The
mandelonitrile derivative may be obtained pure by crystallisation from
alcohol and melts at 58 — 59° :

0-555 gave 26-0 c.c. Ng (moist) at 16° and 748 mm. N = 5-37.
^16^12^3-^ requires N = 5'26 per cent.

■p-Anisoyl-p-methoxymandelonitrile,
OMe-C6H4'CH(0-CO-C6H4-OMe)-CN.

This was prepared from anisaldehyde and crystallised from alcohol ;
it melts at 69—70° :

0-2570 gave 10-6 c.c. N2 (moist) at 12° and 759 mm. N = 4-88.
CjyHjgO^N requires N = 4-71 per cent.

Preparation of a Phthalyl Derivative.
Phthalylmandelonitrile, CN-CHPh-O-CO-CgH^-CO-O-CHPh-CN,

This compound was prepared from benzaldehyde in a similar manner
to the previous derivatives by using phthalyl chloride ; after
crystallisation from a mixture of benzene and light petroleum it melts
at 120°:

0-212 gave 0-0826 HgO and 0-5606 COg. C = 72-12; H = 4-33.

0-154 „ 9-4 c.c. N2 (moist) at 21° and 765 mm. N = 6-99.
Ca^HigO^Ng requires C = 72-72 ; H = 4-04; N = 7-l per cent.

1408 ACYL DERIVATIVES OF ALDEHYDE-CYANOHYDRINS.

Preparation of Cinnamoijl Derivatives.
CinnavioylmandelmitHle, CHPh(0-CO-CH:CHPh)-CN.

A good yield of this derivative is obtained by the action of
cinnamoyl chloride on benzaldehyde in the presence of aqueous
potassium cyanide ; when crystallised from dilute alcohol it melts at
47—48°:

0-486 gave 23-2 c.c. N2 (moist) at 17° and 755 mm. N = 5-5.
Cj^HjgOgN requires N = 5'32 per cent.

Cinnainoyl-^-inethoxymandelonitrile,
0Me-C^H4-CH(0-C0-CH:CHPh)-CN.

A small yield of this substance, melting at 86 — 87°, was obtained by
treating the oily products of the reaction from anisaldehyde with
ether and crystallising the residue from alcohol :

0-519 gave 21-6 c.c. N2 (moist) at 16° and 752 mm. N = 4-8.
C^gHjjOgN requires N = 4-77 per cent.

Prejjaration of va- Nitrohenzoyl Derivatives.
m-Nitrobenzoylmandelonitrile, CHPh(0*CO'CgH4*N02).CN.

The reaction was carried out at a temperature between 40° and 50°,
employing w-nitrobenzoyl chloride, and the derivative, when crystal-
lised from ether, melts at 83 — 84° :

0-2575 gave 23-2 c.c. Ng (moist) at 21° and 760 mm. N = 10-21.
^15-^10^4^2 reqiiij^es N = lO'O per cent.

m.-Nitrohenzoyl-^-iinethoxymandelonitrile,
OMe-CeH4-CH(0-CO-CgH,-N02)-CN.

This derivative, prepared from anisaldehyde, on crystallisation from
boiling alcohol melts at 129—130°:

0-338 gave 26-4 c.c. N2 (moist) at 14° and 757 mm. ]Sr = 9-15.
CjgHj205N2 requires N = 9-0 per cent.

Preparation of a Benzenesulphonyl Derivative.

Benzenesulphonylmandelonitrile, CHPh(0*S02Ph)'CN.

Benzenesulphonyl chloride is shaken with benzaldehyde and an
aqueous solution of potassium cyanide ; the resulting derivative is
recrystallised from dilute alcohol and ether, and melts at 66°. On

CARBONATES OF COPPER AXD THE CUPRICAP.I?0\ATES. 1409

keeping, it undergoes decomposition, the only case yet obsorvod among
the substances described in this paper :

0-6185 gave 27 c.c. Ng (moist) at 20^^ and 758 mm. N = 4-97.
Cj^Hj^OjNS requires N = 5-13 per cent.

Preparation of a C arbelhoxy-derivative.

Carhethoxymandelonitrile, CH Ph(0 • CO2 Et) • CN.

When the calculated amounts of benzaldehyde, ethyl cliloroformate
and aqueous potassium cyanide are shaken together and the tem-
perature kept low, a heavy oil separates. This is extracted with
ether, washed with dilute aqueous potassium hydroxide and then
with water, and dried. On evaporating the ether, the oil distilled
unchanged at 210 — 2 12°/ 90 mm., and was obtained in quantitative
yield :

0-2177 gave 0-510 CO2 and 01115 IT.p. C = G3-7; H-5-G.
0-4895 „ 30-2 c.c. N., (moist) at 21° and 762 mm. N = 7-04.
CijHi^OaN requires C --= 64-39 ; H = 5-36 ; N = 682 per cent.

The Chemical Department,

The University, Bristol.

CLIX. — The Carbonates of Copper and the Cupri-
carhonates.

By Spencer Umfreville Pickering, M.A., F.R.S.

Copper carbonate dissolved in ammonia or in ammonium carbonate
has been used for many years as a fungicide, and, more recently,
the mixture obtained by adding sodium carbonate to copper
sulphate has been advocated for the same purpose, notably by the
Department of Agriculture and Technical Instruction for Ireland,
and by various colonial authorities. This mixture is known as
Soda Bordeaux. What the compound present in it is, appears,
however, to be somewhat uncertain, for much of our knowledge of
the carbonates of copper depends on work of rather ancient date,
although the subject has been ajDproached by several recent
investigators in dealing with the double carbonates of copper and
the alkali metals. What is known on the subject may be briefly
summarised as follows :

The normal carbonate, CuO,C0.2, has not been isolated, but
probably exists in solution to the extent of one part in
4000 — 5000 of aqueous carbonic acid under several atmospheres'

VOL. XCV. 4 Z

1410 PICKERING: THE CARBONATES OP

jDressiiro (Wagner, J. jir. Clicm., 1867, 102, 235). Gay-Lussac
(Traite dc C/tiinic, Pelouze et Fremy, III, 1023) states that it
constitutes the black mineral, mysorin; but this is now known to
be a basic carbonate.

The green dicupric salt, 2CuO,COo,Il20; identical with malachite,
is the ordinary copper carbonate of commerce, and is prepared by*
the action of alkaline carbonates on cojDper sulphate. The blue
precipitate obtained initially in this reaction was stated by
Brunner (Pelouze et Fremy) to be malachite in a different state
of hydration, but, as will be shown below, the primary precipitate
consists of another basic carbonate, which becomes converted into
malachite by a secondary reaction.

The blue, so-called, tricupric salt, 3CuO,2COo,HoO, occurs as
azurite, and is said to be manufactured by a secret process, and
sold under the name of blue verditer.

A true tricupric salt, 3CuO,C02,3H20, is stated by Favre
{Ann. Chim. Phys., 1844, [iii], 10, 116) to be obtained by decom-
posing cuprammonium carbonate with excess of water; but Favre
determined only the copper and carbon dioxide in it, and it is
probable that what he obtained was really the basic cuprammonium
carbonate, which the present writer has obtained under somewhat
similar cix'cumstances.

By adding copper sulphate to a boiling concentrated solution
of sodium carbonate, Field (Quart. Journ. Chem. Soc, 1862, 14,
70) obtained a black precipitate represented by 6CuO,C02, whilst
Deville (Ann. Chhn. Fhys., 1851, [iii], 33, 104) stated that
SCuOjCOo is the comjDosition of this precipitate. Evidence will be
given below to show that these precipitates ai'e not definite in
composition, but consist of mixtures of copper hydroxide with
undecomposed basic carbonates.

The Cu2iricorhonates a?id Double Ca?'hnnofes.

A knowledge of these compounds is essential as a preliminary to
the study of the carbonates of copper.

As has been known for very many years, copjoer may displace
the hydrogen in the salts of ammonium, giving rise to
cuprammonium compounds, the characteristics of which are their
intense purple-blue colour, and the fact that the copper in them
does not respond to the usiial tests for that metal : analogous
compounds are known in which the copper forms parts of the
anion in carbonic and certain organic acids, becoming unrecognis-
able as copper by the usual tests,* and giving to the salt an

* Wood and Jones state that snch sohitious giro the ndinary reaction with ferro-
cyanide ; tlie explanation of this appartiit difl'oxncc of oiiiiiion will be ujade cvideut
below.

COPPEK AND THE CUPRICARBONATES. 1411

intensely blue colour. The existence of these comioounds has not,
however, been sufficiently realised, partly because they have never
received a distinctive name, and partly because they have never
been isolated. They may be conveniently designated as cupri-
carbonates, cupritartrates, etc.

Deville (Ann. Ghim. Phys., 1851, [iiij, 33, 75) first described
the deep blue solution which is obtained by dissolving a carbonate
of copper in strong solutions of the mixed carbonate and acid car-
bonate of the alkali metals. This blue solution, in the case of the
sodium carbonates, yields, on standing, rather light blue crystals
of CuCOvjNaoCOyjSIIoO, * leaving the liquid only slightly coloured ;
indeed, according to the present investigation, it is only when the
jiroportion of normal sodium carbonate present is considerable
that the liquid retains more than a faint trace of copper. A
strongly alkaline solution of tliis nature was introduced by Soldiani
{Gazzetla, 1876, 6, 322) as a substitute for Fehling's solution in
the estimation of sugar (see also Ost, Ber., 1890, 23, 1035).

The change of colour accompanying the crystallisation of the
double salt is sufficient proof that the liquid cannot be a mere
solution of the crystals; the latter are considerably lighter in
colour than copper sulphate, whereas the liquid yielding them (as
will be shown) is of a far deeper blue than the normal sulphate.
Max Groger, also (Ber., 1901, 34, 429), pointed out that the
crystals will not redissolve in the mother liquor (although this
statement requires sUght modification), and are decomposed by
water. The non-identity of the crystals and dissolved substance
has been fvirther emphasised by Reynolds (Trans., 1898, 73, 2G6)
and by Wood and Jones {I'roc. Canih. Fhil. Soc, 1907, 14, 174),
who proved the existence in the liquid of a highly coloured anion,
and that, on electrolysis, copper is liberated at both poles.
Reynolds prepared many cr5'stalline double carbonates of potassium
and other dyad metals, the majority of them containing 4H2O;
Wood and Jones did so as well, and they note similar colour
changes to those observed in the case of copper, that in the case
of the cobalt compounds being specially remarkable.

The alkaline carbonates are not the only salts which form
deep blue solutions with copper; the tartrates, succinates and
oxalates are known to do so in the presence of excess of alkali,
and it is probable that many organic salts would behave in the
same way. Reference to the possible constitution of these will
|be made later on.

For the determination of small quantities of copper in the

* The text-books erroneously f|Uote OH^O. Tlie writer, and others also, have
|otuid the crystals to contain 3H.,0, retaining this water at 100°.

4 z 2

1412 nCKERING: THE CARBONATES OF

present investigation, the colorinietric process witli ferrocyanide
was adopted. Using Nessler cylinders, it is possible to detect
0-00005 to 000003 per cent, of copper in solution, or O'OOOS per
cent, when a few c.c. are similarly examined in a test-tube. Where
the copper is in the form of cupricarbonate, the alkaline liquid
containing it must first be nevitralised, using a scrap of litmus
paper as indicator; but excess of acid interferes with the ferro-
cyanide reaction. For qualitative testing, the acid may be run
down the side of the tube containing the liquid, when, if cupri-
carbonates are present, a red ring forms in the neutral zone.

The cupricarbonates give a clear yellow colour with potassium
ferrocyanide, but as the change between them and copper carbonate
seems to be a reversible one, the red colour of copper ferrocyanide
gradually appears on standing, after a time varying between a
few seconds and many hours, according to circumstances.

The Tteaction hctiveen Cojifcr Salts and Sodium Carhonates.

When sodium carbonate and copper sulphate solutions are mixed,
some carbon dioxide is evolved, and a bulky, blue precipitate is
thrown down.

To ascertain its comioosition, the carbonate was added to a
solution of cojDper sulphate sufficiently weak to ensure the retention
of any carbon dioxide liberated (0"05 per cent, of copper), and
alkalinity was found to be attained when 1'61 molecules of sodium
carbonate had been added for every molecule of cojjper sulphate
present (mean of four concordant determinations).

Various quantities of sodium carbonate were then added to the
same amounts of copper sulphate, the solutions filtered immediately,
and tested for copper. By a series of approximations, it was found
that the precipitation was practically complete when the carbonate
amounted to (exactly) 1'6 molecules. As this coincides with the
appearance of alkalinity, the reaction evidently is a simple one, j
and does not occur in two stages, as when an alkali hydroxide is
added to coj^per sulphate, in which case the whole of the metal is I
first precipitated to form one basic sulphate, and this reacts withf
a further addition of alkali to form a more basic one before thf|
liquid finally becomes alkaline (Pickering, Trans., 1907, 91, 1982),

The precipitate was found to contain no traces of sulphate unles I
the copper was only partly precipitated, and then in only minut
quantities; its formula, therefore, is, presumably, 5CuO,2C02, itj
formation being represented by the equation :

10CuSO4 + 16Na2CO3 = 10CuO,4CO2+ 10Na.SO,,4- 12NaHC03.

This was verified by determining the amount of sodium hydrogej

COPPER AND THE CUPRICARRONATES. 1413

carbonate in an aliquot portion of the filtrate: the mean of the
two determinations gave exactly 12NaIIC03 for every IOCUSO4
taken. None of the sodium carbonate, therefore, is retained in
combination with the precipitate. [This could not have been
ascertained satisfactorily by examining the precipitate, as washing
it would probably have removed any sodium carbonate combined
with it, as in the analogous cases of the basic sulphates.]

The precipitation of copper, it was said above, was practically
complete when 1"6 molecules of sodium carbonate had been added
to each molecule of copper sulphate; it is never absolutely so,
because the basic carbonate dissolves in the sodium hydrogen car-
bonate formed in the reaction; but the quantity present when
dealing with very dilute solutions is barely recognisable. Where
more than 1"6 molecules of sodium carbonate are added, the
amount of copper dissolved becomes more considerable, and with
stronger solutions the liquid becomes quite blue. Exposure to the
air, by increasing the proportion of acid carbonate present,
increases the amount of copper dissolved.

On heating strong solutions of copper sulphate and sodium car-
bonate, the precipitate speedily blackens, and after prolonged
boiling it contains only traces of carbonate. To ascertain whether
confirmation could be obtained of Field's statement that 6CuO,CO.,
is formed in this way, or of Deville's, that 8CuO,COo is formed,
copper sulphate solution was added to a boiling concentrated
solution of sodium carbonate, and some of the precipitate removed
after two, ten, and thirty minutes ; these portions, after drying
at 100°, were found to contain 94" 1, 94"9, and 96'5 per cent, of CuO,
respectively, thus indicating a continuous decomposition ; all of
them were more basic even than 8CuO,C02, which contains 935
per cent, of CuO.

The Carbonate, 5CuO,2COo.

The carbonate obtained as above is of a full blue colour, and
rather watery in appearance, being quite different from the lighter
blue and more opaque basic sulphates, and from the other blue
basic carbonates to be described immediately. Although it is
decomposed when heated in a moist condition, it can be dried over
sulphuric acid (when it contracts to a brittle, dark blue mass),
and may then be heated to 100° without decomposition. After
drying thus, it is dark green, and contains SHgO (Pound,
HoO^ 10-36; 5CuO,2COo,3H20 requires HoO = 1000 per cent.). It
retains this colour on cooling in dry air, but on exposure to moist
air it becomes blue again.

The carbonate, 5CuO,2C02, may be deprived of its carbon

1414. PICKERING: THE CARBONATES OF

dioxide entirely, forming copper hydroxide, by leaving ifc in contact
with cold saturated sodium carbonate solution for some days or
■weeks, according to the temperature. On the other hand, it
readily takes up more carbon dioxide if left in contact with a
solution of sodium hydrogen carbonate for some days, the pre-
cipitate contracting to a compact, green powder, which is malachite,
2CuO,CO.,,H20. This change is evidently not a direct one, and
is preceded by the partial dissolution of the basic sulphate in the
liquid, for this becomes more or less blue, and the malachite
deposited is found to adhere to the containing vessel, and to consist
of spheres of great regularity, often resembling a very uniform
emulsion. After long standing, these spheres collect together, by
redissolution and redeposition, in circvilar masses, suggesting the
botroidal formation of natural malachite.

When washed on the filter with well-boiled water, or with a weak
solution of normal sodium carbonate, 5CuO,2C02, it gives no trace
of copper to the liquid, but it does so with aqueous carbonic acid,
although to a smaller extent than with a solution of sodium
hydrogen carbonate, and is converted by it, as by the acid car-
bonate, into malachite. It is probably the normal copper carbonate
and a double carbonate of copper and sodium which constitute
the soluble primary products in these two cases, respectively.

In spite of the insolubility of the basic carbonate in normal
sodium carbonate, the addition of this latter to a mixture of the
basic carbonate with sodium hydrogen carbonate increases the
amount of copper passing into solution, and deepens the colour of
the liquid. This is due to the formation of a-cupricarbonate, as
will be explained below (p. 1422).

The basic carbonate generally changes into malachite if left in
the mixed liquid from which it had been precipitated, and more
readily the more nearly the amount of sodium carbonate used for
its precipitation approximates to that required by the equation
given on page 1412.

The Reaction hetween Cojij^er Sulphate and Acid Sodium
Carbonate, 5CuO,3C02.

When weak solutions (0"0o per cent, of copper) are taken, the
addition of sodium hydrogen carbonate to copper sulphate throws
down rather gradually a light blue, opaque and finely divided
precipitate, which is very different in appearance from that given
by the normal carbonate. In the accompanying table are entered
the results of a serias of experiments with different proportions of
the reagents, the total volumes of the liquids being the same in
all cases.

COPPER AND THE CUPRICARBONATES.

1415

The precipitation of the copper is never complete, but reaches
a maximum of 92 — 93 per cent, when three molecules of sodium
hydrogen carbonate, or more, are iDreseut for every molecule of
copper sulphate. The amount of acid carbonate used u]i for the
copper precipitated is always more than two equivalents, and, with
the exception of the extreme experiments — probably with the
exception only of the last three experiments, as the first one is
uncertain owing to the smallness of the precipitate obtained — is
j^ractically constant at about 2*15 molecules of sodium hydrogen
carbonate for every molecule of copper sulphate. The only way
in which more than two molecules of sodium hydrogen carbonate can
be used up is by the precipitate combining with additional sodium
carbonate, and some perplexity was caused by not being able to
find any alkaline carbonate in the washed precipitate. It was
ascertained eventually that such carbonate was present, but was
given up at once on washing. The examination was made by
measuring the liquids after mixing them, and again after filtration ;
by then making an assumption, which could not be far from the
truth, as to the density of the precipitate, the amount of liquid
mechanically retained by the latter covxld be calculated. The pre-
cipitate was then washed, and the alkali determined, both in the
original filtrate and in the washings, when it was found that the
latter contained the missing alkali.

Table I.
Precipitation of Cojyjjcr Sulphate hy Acid Sodiam Carbonate.

Mols. NaHCO:j

Conipositiou

Mols. NaHCO,

Mols.

used for

of tlie precipitate

added to
mol. CuSOj.

CUSO4
precipitated.

1 mol. -atom Cu
iu precipitate.

>,

1

CuO.

SO3.

COo.

1.

0-41

0-123

2-77

—

—

2.

0-82

0-307

2-23

—

—

—

3".

1-00

—

—

76-133

2-603

21-265

4.

1-64

0-660

2 13

—

—

—

5.

2-00

—

— .

74-816

2-743

22-441

6.

2-46

0-890

2-12

—

—

7.

2-87

0-922

2-11

—

—

8.

3-28

0-933

2-13

—

—

9.

3-1)0

0-913

2-15

—

—

10.

4-00

—

—

76-829

0-849

22-322

11.

4-10

0-908

2-16

__

12.

5-36

0-928

2-12

—

—

13,

6-00

—

—

7.5-912

0-o55

23 -535

14.

6-56

0-926

2-23

—

—

1.5.

9-84

0-925

2-29

.

.

1(5.

12-30

0-892

2-41

17.

16-43

0-888

2-69

—

—

—

Besides sodium carbonate, the precipitate contains considerable
quantities of basic sulphate, especially when the precipitation of

1416 PICKERING: THE CARBONATES OF

the copper is less complete. Analyses of the washed precipitates
obtained in four cases are given in the table. On the assumption
that the SO3 is present as the lowest basic sulphate of copper,
4CUO.SO3 (any other assumption gives less concordant results), the
composition of the basic carbonate of cojoper is found to be
lOCuO, with 5-85C02, 6-1800o, OoOCOo, and 5-78C02, respectively.
The mean of these gives lOCuOjS'SCOo, which is, within the
limits of error in such a case, 5CuO,3COo. That this carbonate
should combine in a loose fashion with some of the sodium car-
bonate is analogous to what occurs in the case of the basic sulphates
(Pickering, Trans., 1907, 91, 1991).

This carbonate can be dried without any signs of decomposition,
and it then forms a light blue powder, quite different from the
dark, brittle 5CuO,2COo. On heating at 100°, it remains blue,
and then retains about TH^O. On boiling with water, it gradually
blackens, as all the other basic carbonates do.

When concentrated solutions of copper sulphate and sodium
hydrogen carbonate are mixed, considerable quantities of carbon
dioxide are evolved, and the light blue precijiitate formed re-
dissolves, producing a deep blue liquid; warming increases the
amount of copper which can be thus dissolved, but on boiling, or
before, the substance in solution decomposes rather suddenly,
forming a green precipitate of malachite, and leaving the liquid
only slightly blue. This decomposition often takes place during,
or after, filtering; but, if it does not do so then, the dark blue
solution decomposes in another manner, depositing gradually
throughout twenty-four hovirs, or more, fairly light blue crystals
of the double salt, CuS04,Nao003,3H20, and leaving the liquid
with often only a trace of copper in it. These changes will be
dealt with more fully below.

The basic carbonate, 5CviO,3COo, just like 5CuO,2C02, dissolves
slightly in aqueous carbonic acid, but is insoluble in the normal
carbonate and in pure water.

The Carbonate, 8Cu0,3C02,6H20.

"When the crystals of the double salt just mentioned are washed,
they retain their form, but become opaque, and are found to have
parted with the whole of the sodium carbonate present in them,
but none of the copper. The residue is of a rather dark blue
colour, and, when dried at 100°, becomes green. It is quite unlike
any of the other three basic carbonates, and is evidently a definite
compound. Analyses of three different preparations of it gave the
formula as:

COPPER AND THE CUPKICAK150NATES. 1417

7-9SCuO,3CO.„6-12II.O
8-25CuO,3COo,6-54H."0
7-83CuO,3CO",,rv95ir,0

Mean 8-02CuO,3CO2,6-20H2O

Tlie weight became constant rather slowly at 100°, and one of
the samples evidently still retained an appreciable excess of water.

This basic carbonate behaves like the others towards solutions
of sodium carbonate, sodium hydrogen carbonate, and carbon
dioxide; and a similar behaviour is exhibited by the crystalline
double carbonate.

Tricupric Carbonate.

Attempts to prepare tricupric carbonate by the method employed
by Favre (Joe. cit.) failed. Malachite was digested for two days
at 25° with a concentrated solution of ammonium carbonate; but
the deep purple liquid thus obtained gave no precipitate at all on
dilution. On adding alcohol, a few small crystals of a purple
colour, very soluble in water, were obtained on one occasion, these
evidently being a cuprammonium salt; on another occasion a good
crop of shining, purple, crystalline plates was obtained. These
were quite insoluble in water, and consisted, apparently, of a basic
cuprammonium carbonate.

When concentrated solutions of coj^per suljihate and ammonium
carbonate were mixed, a deep purple solution was obtained, which,
on heating, gave some precipitate of malachite, and, on dilution,
gave a bulky, blue precipitate, which proved to be a basic sulphate
of the formula 15CuO,S03. The addition of alcohol gave, in one
instance, a few blue crystals, which were insoluble in water, and
evolved some ammonia on heating, being probably a double copper
ammonium carbonate analogous to the double copper sodium
carbonate; but, generally, dilution with alcohol gave only a crop
of crystalline needles of cuprammonium sulphate.

The basic sulphate just mentioned has not been obtained before.
The analytical values were Cu : S03 = 15: 0'985. It is noticeable
that such a suljihate bears a very simple relation to two of the
other basic sulphates already known, namely, lOCuOjSOg and
5CuO,S03 (Pickering, Trans., 1907, 91, 1982). Attention has pre-
viously been drawn to the predominance of 5 as the coefficient of
the equivalents of metallic oxide in basic sulphates in general.
The new sulphate, 15CuO,S03, can be dried by heat without any
blackening, and, therefore, contains no uncombined hydroxide.

1418

PICKERING: THE CARBONATES OF

The Soluble Co2)fer Comiwunds.

Double Carbonate and Giipricarbonate.

To gain further information as to the nature of the changes
accompanying the dissolution of copper carbonate in alkaline
liquids, the same volume of copper sulphate solution was added
to a constant volume of a solution of alkali, consisting of normal
and acid sodium carbonates in different proportions. In one case
(first half of table II) the molecular proportion of the two
carbonates (representing the molecule of acid carbonate as
NaoH2(C03)o) was 5'6 times that of the copper sulphate; in the
other (lower half of the table), it was only 2"24. The total volumes
of the mixed liquids were the same throughout each series, but

S I

o ?^

Ri'-

Relative molecular proportions of the carbonates of sodium.

were different in the two series, the solutions being taken of the
maximum possible strength consistent with avoiding any separation
of sodium carbonate at the temperature of the experiments, which
was 22°. Some of the liquid was removed after various intervals
of time, and filtered, and the amounts of electropositive and
electronegative copper in it determined.

The first set of observations, made five minutes after the mixing,
shows that, so long as the acid sodium carbonate predominates, all
the copper in solution is electropositive, but that, as the proportion
of normal carbonate is increased, electronegative copper appears,
and soon becomes the sole product. The significance of the letters
D and M will be explained below.

This is seen better in the curves A and B in the accompanying

COPPER AND THE CUPJUCAHI50NATES. 1419

figure, where the percentage of copper in solution is plotted against
the proportion in which the two sodium carbonates are added, the

Table II.

CopiJir Sulpliate added So Mixtures of Noniuil a/ul Acid Sodium

Carhonatcs.

(The + and — signs indicate nature of the copper in solution.)

Mols. alkali Percentage Actual perceuUgo ol'

to each Cu taken, of total copper in lii[ui(l after :

copper

Na-iCOy. 2NaHC03. dissolved. 5 minutes. 24 hours. 48 liours. 72 hours.
Series /, with CuSO.i + 5-6|^^^^^^ | + SOOIip.

1.

0-00

5-6

9

+ 0-036

+ 0-040

+ 0-003.1/

—

2.

1-12

4-48

12

+ 0-050

+ 0-02-2^^

+ 0-002;)/

—

3.

2-24

3-36

23

f +0-072
\ -0-016

+ 0-004^
-0-004^^

+ 0-001,,
-0-003'"

—

4.

3-36

2-24

26

-0-lOS

-0-0167)

-0-002Z)

—

5.

4-48

1-12

18

- 0-076

1 -0-058

-0-054

-0-0327:)

6.

5-6

0-00

6

-0-026

-0-022

-0-022

-0-023

Series II,

with Cu

S04 + 2-24^

rNa,C03 \
(SNaHCOg/

+ 400HoO.

7.

0-00

2-24

1-5

+ 0-013

+ 0-013

+ 0-002.1/

—

8.

0-45

1-79

2 0

+ 0-016

trace M

—

—

9.

0-90

1-34

1-9

+ 0-015

+ 0-015

+ 0-001:1/

—

10.

1-34

0-90

2-0

+ 0-016

+ 0-014

+ 0-007/>'

—

11.

1-79

0-45

2-5

+ 0-021

+ 0-021

+ O-0OU/

—

12.

2-24

0-00

1-1

-0-009

-0-027

—

-0-018*

* Malachite appearing

after ten days

dotted portions of the curves representing the results wherein the
copper is electronegative. The variation in the amount of copper
passing into solution is continuous throughout, showing no abrupt
change when electropositive copper gives place to electronegative.

The point at which this change occurs seems to depend solely
on the proportion of normal sodium carbonate to copper. This is
shown more clearly by the series of experiments in table III,
wherein this ratio was altered, while the proportion in which the
two carbonates were used was kept constant. This set of experi-
ments and the first series in table II give, respectively, 3'3 and
2*2 molecules of sodium carbonate added for every molecule of
copper sulphate as the point at which electronegative copper
appears, or 11 and 13 molecules of sodium carbonate for every
atom of copper passing into solution, although the ratio of normal
carbonate actually in the liquid would be rather lower, owing to
some carbon dioxide being given off in the precipitation of the
basic salt.

1420

riCKERING : THE CARBONATES OF

The amount of copper passinr; into solution evidently depends on
the relative proportion of the two sodium carbonates present, but,
with any given mixture of these, it is directly proportional to the
total carbonate present. On plotting out the values in table III,
they are found all to lie on a straight line up to 18'7 molecular
proportions of the carbonates, at which point the dissolution of
the copper taken becomes complete. The total amount of copper
which can be obtained in such solutions reaches about 0"15 per
cent., and this has never been exceeded in any of the present
experiments.

Table III.

Copper Sulphate added to Equimolecidar Mixtures of Normal and
Acid Sodium Carbonate.

icCuSO^ + l-12Na2C03 + l-12(2NaHC03) + 25OH2O or

CuSO,4-,{2^:|?^5J+110,H,O.

x.

y-

Percentage

of total

copper

dissolved.

Actual nercentage of
copper iu liquid after :

5 minutes.

24 hours.

48 hours.

72 hours.

1.

2.
3.

0-72
0-60

0-48

3-1
3-7

4-7

5

8

16

+ 0-043
+ 0 060

f + ?
t -0-094

+ 0-034
f +0-050
', -0-015
+ C-045„
-0-048^

+ 0-033 J/
+ 0-004^,
-0-005'^
+ 0-007Z)
-0-004 J/

-0-003

+ ? z> 1

-0-00Ci»/ j"
+ 00 I) \
-0-006il/]'

4.

0-36

6-2

27

-0-120

-0-050Z)

-0 009^^

— I)

5.

0-24

9-3

50

-0148

-0-080

-OOIOZ?

— Mf

— JJ

— B

6.
7.

0-12
0-04

18-7
56 0

100
100

-0-128Z) -0-018Z)
-0 043 -0-024Z>

-0-0167)
-0-016/J

The highest two results from table III are inserted in the
diagram.

A rise in temperature increases slightly the amount of copper
passing into solution, and an increase in the dilution reduces it,
whilst the proportion of the dissolved copper which is in the
electronegative condition is increased, both by rise of temperature
and by dilution, very conspicuously so by the former. These facts
are illustrated by the following observations made with a solution
of the same composition as No. 3 in table II :

Percentage of the
Passing Percentage of dissolved copi)er which

into solution. total copper. is electronegative.

At 5° 19 0

At 20° 20 6

At 50° 25 71

COPI'ER AND THE CUPIUCAKBONATES. 1421

Percentftge of the

Pas.sinf» Percentage of ilissolved cojiper wliich

into solution. total cojiper. is eleetionegative.

AVitli 80 H.,0 14 0

,, 600 H.'0 11 2-5

„ 900 n.'0 10 12

,, 1500 H..0 7 16

,, 6300 HoO 3-6 24

Whether the dissolved copper is in the electropositive or electro-
negative form, all these solutions are intensely blue, the depth of
colour being far greater than that of copper in the form of sulphate,
although the quality is the same, and quite unlike the violet of
the cuprammouium compounds. By direct comparison, the colour
of the compound containing electropositive copper was found to
be 30 times more intense than that of copper in copper sulphate,
whilst that with electronegative copper was 80 times more intense.

The vai'ious solutions recorded in tables II and III, together
with the precipitates contained in them, undergo a marked change
when kept for a day or two, this change consisting in the formation
of either malachite or of the crystalline copper and sodium car-
bonate, sometimes of both together. These substances are deposited
from the solution, and at the same time most, or all, of the basic
carbonate present is likewise changed into them, the liquid
becoming almost colourless, and retaining only a trace of copper.
The change is a rapid one, but not instantaneous. The appearance
of malachite is indicated in the tables by M, and that of the double
salt by D. The copper finally remaining in solvition is generally
greater when malachite is formed than when the double salt is the
product; the results in series II of table II, and those in table III,
show this best.

Whether malachite or the double salt is formed seems to be
determined to some extent by arbitrary conditions, but, as a rule,
the former appears first in, or is the sole product /rom, solutions
containing electropositive copper, and the double salt from those
containing electronegative copper; thus, of seven instances in the
tables where malachite was the prime or sole product, the copper
was electropositive in six of them, whilst out of ten instances where
the double salt v/as the prime or sole product, seven are cases
where the dissolved copper was electronegative. Many other
instances of a similar character were observed. Some malachite
often appears after the double salt has begun to crystallise, and
it would seem as if the crystals themselves sometimes become
converted into malachite (see No. 3 in table II). Where the
amount of copper in solution is small, and that of sodium carbonate
large, as in No. 6, table II, no formation of either malachite or
double salt occurs, even after many weeks; where such conditions

1422 PICKERING: THE CARBONATES OF

are approximated, as in Nos. 5 and 12, the formation of these sub-
stances is murh retarded. With larger proportions of normal
carbonate present, the amount of electronegative copper retained
permanently in solution could, no doubt, be increased beyond the
maximum reached in any of these experiments (0'023 per cent, in
No. 6), but such solutions would not be permanent when exposed
to the carbon dioxide in the air.

It is j^ossible now to explain the somewhat puzzling reactions
occurring when a concentrated solution of copper sulphate is added
to a concentrated solution of sodium hydrogen carbonate. The
basic carbonate, 5CuO,3COo, is first precipitated, and then gradually
absorbs carbon dioxide from the sodium hydrogen carbonate
present, passing into solution as the normal copper carbonate, or,
rather, as a double carbonate of copper and sodium, forming a
deep blue liquid wherein the copper is electropositive. On
standing, this soluble compound gives rise either to the crystalline
double carbonate, or else decomposes into malachite, nearly all the
copper going out of solution. On heating to the boiling point, the
change into malachite always takes place if the solution contains
miich copjDcr. If the light blue liquid and the malachite resulting
from this change are boiled together for some time, the proportion
of normal sodium carbonate in the liquid is increased, and the
precipitate gradually redissolves, forming again a deep blue liquid,
but one in which the copper is now electronegative, being present
in the form of cupricarbonate. This liquid, on standing, nearly
always yields the crystalline double carbonate, and not malachite.

The change from the soluble compound with electropositive
copper, into the cvijiricarbonate, with electronegative copper, is a
reversible one. On taking a rather weak solution of the former
and heating it to boiling, it becomes darker, and the copper no
longer reacts with f errocyanide ; but, on cooling, it becomes lighter
again, and responds to the ferrocyanide test.

The experiments 6 and 12 of table II, wherein no sodium
hydrogen carbonate was added, present no difficulty in accepting
the preliminary step in the dissolution of the copper as
being the formation of normal copjoer carbonate from the basic
carbonate and sodium hydrogen carbonate, for some of the latter
will have been formed during the precipitation of the basic salt.
It is found, however, that any of the basic carbonates, after being
thoroughly washed, will gradually dissolve to form cupricarbonate
when boiled with a concentrated solution of sodium carbonate;
even ignited copper oxide will do the same. It is probable that,
in such cases, the carbon dioxide necessary to convert them into
normal cojjper carbonate is derived from the partial decomposition

COPPER AND THE CUPRICAPiP.ONATES. 1423

of the soduim carbonate into liydroxidc and carbon dioxide. Such
a decomposition has been shown to occur readily by fusion
(Pickering, Trans., 1887, 51, 72), and it need occur only to a
minimal extent in a boiling solution to account for the facts; since
the products (both sodium hydroxide and carbon dioxide, on the
view suggested below) would be utilised at once to form the cupri-
carbonate.

The cupricarbonate has the power of oxidising dextrose with
the precipitation of cuprous oxide. This action takes place in the
cold, or, more rapidly, on heating, and is preceded by the formation
of some soluble compound of the cupricarbonate with the sugar,
for the amount of coj^pcr passing into solution at first is greatly
increased by the sugar. No such action, nor any precipitation of
cuprous oxide, occurs when the soluble compound present is that
containing electropositive cojDper.

Action of Sodium Hydroxide.

When sodium hydroxide is added to a solution of copper car-
bonate in sodium hydrogen carbonate, the latter becomes converted
into normal sodium carbonate, and the same result is obtained as
if excess of sodium carbonate is added, namely, the formation of
the cvipricarbonate ; but when the amount of sodium hydroxide is
further increased, it abstracts carbon dioxide from this cupri-
carbonate, and a blue basic carbonate of cojoper is precipitated,
leaving only a trace of copper in the solution. This precipitate is
evidently a mixture, as it blackens in joarts on drying at 100°, and
three different preparations of it were found to contain, after
drying, copper oxide varjdng between 76'3 and 90"2 per cent.

On adding still further excess of sodium hydroxide, this pre-
cijDitate again dissolves, to form a deep violet-blue liquid, the
dissolution becoming complete when about 300 molecules of sodium
hydroxide are present for every atom of copper. The coloration
is more intense than that of the cupricarbonate, being about 200
times deeper than that of copper in the form of sulphate, although
accurate comparison is impossible, ow'ing to the difference in the
tone of the colour. A similar solution may be obtained by digesting
any of the copper carbonates with concentrated sodium hydroxide.
This liquid, in which the copper is also electronegative, appears
to be quite stable, and does not give rise to malachite or the
crystalline double carbonate, as the cupricarbonate does. The
strongest solution of it which has been obtained contained 0"4 per
cent, of copper. On dilution with a large excess of water, a basic
carbonate is thrown down, "but the copper in solution remains

1424 PICKERING: THE CARBONATES OF

electronegcativc; dilution with a smaller amount of water gives a
slight precipitate of copper hydroxide, due, no doubt, to the
secondary reaction of the excess of alkali on the basic carbonate
first deposited. Prolonged boiling also results in the precipitation
of some hydroxide, but about 0*2 per cent, of copper remains
permanently in solution.

This compound also oxidises dextrose, with the precipitation of
cuprous oxide, and, moreover, it has the property of combining with
cellulose. On filtering through paper, all the copper is retained
by the paper, as if it were present as an insoluble precipitate.
Likewise a piece of filter paper shaken up with the liqiiid renders
the latter colourless, the paper becoming violet-blue. When, how-
ever, the latter is washed, the excess of alkali necessary for the
existence of the copper compound is removed, and only a basic
carbonate of copper is left, the paper appearing to have been
unaffected by the changes.

The existence of these soluble copper compounds explains why
the results obtained in the determination of copper by precipita-
tion with potassivim hydroxide nearly always give values which are
too low, for the potash generally contains carbonate, and one or
other of these soluble compounds with electronegative copper will
be formed. Added to this, it may be mentioned, copper hydroxide
has been found to dissolve in ordinary distilled water to the extent
of one part in 800,000.

Nature of the Soluble Co7?ipounds.

It has been assumed by Reynolds, and by Wood and Jones
(loc. cit.), that the deep blue compound in a solution of copper
in sodium carbonate has the same empirical formula as the double
carbonate which crystallises from the liquid. No evidence, how-
ever, has been brought forward to prove this, and very little is
afforded by the present work. That the basic carbonates require
the addition of carbon dioxide before they will dissolve shows that
the jDroportion of CuO : COo in the soluble compovmds is gi'cater
than it is in the basic carbonates themselves; its decomposition by
heat (which would tend to deprive it of carbon dioxide) into the
basic carbonate is also in accordance with this view; it is probable,
too, that the two soluble compounds have very similar formulae,
as the passage of the one into the other does not affect the
regularity of the curves representing their formation (p. 1420).

As regards the soluble compound containing electronegative
copper (the cupricarbonate), somewhat stronger evidence has been
obtained, as follows : If the compound in solution has the same
formula as the double carbonate, its formation from malachite
would result from an interaction with the two sodium carbonates

COPrER AND THE CtJPRICARBONATES. 1425

in equiniolcculai" proportions (taking 2NanC03 as the molecule),
thus :

2CuO,CO. + NaoCOy + 2NariC03 = 2(CuC03,Na2C03) + H.O.

Now, when one gram of malachite was digested for twenty-four
hours at 18° with 100 c.c. of a concentrated solution containing
5 molecular proportions of the mixed carbonates, the percentage
of copper passing into solution (which was electronegative in all
cases) was found to be that rejiresented in curve C in the figure
on p. 1418, the maximum (0'048 per cent.) being attained •when
the two carbonates were present in about equimolccular pro-
portions, as required by the above equation ; the actiial position
of the maximum is at about 55 per cent, of the acid carbonate, the
slight excess of this which has thus been required being, no doubt,
due to the malachite having contained a little of the more basic
carbonate, 5CuO,2002. A similar position of the maximum is
seen in the curve A, but here it is shifted somewhat in the other
direction, as there was a loss of some carbon dioxide from the
liquid in the formation of the basic carbonate, as already explained.
In the case of curve B, the shifting of the maximum is very great,
as a similar loss of carbon dioxide would leave but little normal
sodium carbonate in the liquid.

The similarity of the curves A and C, especially as regards the
concavity of the first portions, is noteworthy.

Assuming that the crystalline double salt and the two soluble
compounds have all the same empirical formula, we may assign to
the crystalline salt the constitution of a molecular compound,
CuC03,NaoC03. In colour, it is intermediate between an ordinary
blue copper salt and a colourless salt, and in this respect closely
resembles the double sulphates. With these, the evidence that
they are simjoly additive compounds is strong, for their specific
heats ax'e very nearly the sum of the specific heats of the component
sulphates (Pickering, Trans., 1886, 49, 12). Some of the double
sulphates, for example, magnesium potassium suliohate, are decom-
posed by water, like the copper sodium carbonate, whereas others
are stable in solution, for example, the copper jDotassium sulphate,
but such differences are simply a question of the magnitude of
the thermal changes involved {loc. cit., p. 15).

To explain the existence of an isomeride of the double carbonate,
but one still containing copper in the electropositive condition, the
transposition of the copper and sodium atoms would appear to be
satisfactory :

r. becoming Cu<;.^ ,

Cu<^co ^^p-m

VOL. XCV. 5 A

1426 PICKERING : THE CARBONATES OF

and the second compound may be conveniently termed a sodio-
cupric carbonate to distingiiisli it from the double salt.

In the other soluble isomeride, the cupricarbonate, the copper
is electronegative, and cannot, therefore, be regarded as replacing
hydrogen in hydroxyl; the only alternative is that this must be
united directly with the carbon, just as in the analogous
cuprammonium compounds it is united directly with the nitrogen.
This may be represented by :

NaO-COa

Cu .

NaO-COg

Such a representation is, however, not altogether sufficient, for
it docs not explain why a large excess of carbonate should be
essential for its existence, nor why it should act as an oxidising
agent, and decompose with the formation of cuprous oxide. There
is, also, the existence of a fourth compound of a similar natvire,
obtained by sodium hydroxide, to be reckoned with.

The difficulties may be removed by supposing the copper atom
to act as a tetrad, and to attach to itself either the oxygen from
sodium hydroxide, or the CO3 from NaoCOa, whilst the other
oxygen atoms in the molecule become converted into hydroxyl, for
which, we know, there is a strong tendency in the case of all
carbonates. The two compounds would then become :

a-C U2)ricarho7iate. ^-G wpricarh onate.

Cu=:C<X>0 Cu=0

NaO— C<V NaO— C<?

the a-cupricarbonate being the compound formed by the action of
excess of sodium carbonate on the sodiocupric carbonate
( = Na2Cu(C03)2 + Na2C03), and the /3-cupricarbonate being that
formed by excess of sodium hydroxide ( = Na2Cu(C03)o + NaOH).
A doubling of the proportion of sodium carbonate or of hydroxide
united with the cupricarbonate nucleus would give a more sym-
metrical form to the molecules. Both formulas represent the
presence of loosely attached atoms of oxygen, which would be
readily given up to an oxidisable substance like dextrose, leaving
a residue with excess of sodium or hydrogen atoms, the resvilt of
wiioh would be the reduction of the copper to cuprous oxide. The
formula for the a-cupricarbonate, also, well expresses its decom-
position by sodium hydroxide, carbon dioxide being abstracted
from it, and a basic carbonate being produced in consequence.

COPPER AND THE CUPRICARBONATES. 1427

Fehling's solution evidently contains a compound analogous to
one or other of the cupricarbonatcs, electronegative copper being
present in it, and an excess of alkali being essential for its
existence.

The suggestion has arisen that what is represented as tlie
;8-cupricarbonate may really be a sodium cuprate; this cannot be
absolutely negatived, although it is improbable. Ignited copper
oxide does dissolve to form a light violet-blue solution in sodium
hydroxide, even when the latter has been prepared from sodium,
and with the exclusion (as far as possible) of carbon dioxide; but
the amount passing into solution never exceeds 002 per cent, of
copper, as against 04 per cent, obtainable when copper carbonate
is dissolved in soda of the same strength. The most probable view
is tliat the cuprate does exist, but is a different substance from
that described as the )8-cupricarbonate. The limiting product of
the action of lime water on copper sulphate is, probably, also a
cuprate, its formula being CuO,3CaO (Pickering, Trans., 1907, 91,
1991). The addition of sodium carbonate to a mixture of copjicr
oxide and sodium hydroxide does not increase the amount of copper
passing into solution.

The analogy drawn above between the double carbonates and
double sulphates of copper when in the crystalline condition is, no
doubt, sound, but it is questionable whether it can be legitimately
pushed any further, for, although the double sulphates, like the
carbonates, exist in three different modifications, the second and
third modifications of them can exist in the solid condition only.
When the crystalline double sulphate is dehydrated at 100°, it
forms a blue powder, but this, on heating to 150 — 200°, becomes
quite white, the change being accompanied by an evohition of as
much as 3220 cal. (calculated for ordinary temperatures) ; the
white modification, in its turn, becomes converted at 300 — 400°
into a green modification, which, being formed with an absorjD-
tion of 1918 cal., is somewhat imstable, and easily passes back into
the blue or white modifications (Pickering, Trans., 1886, 49, 1).
There is, however, no evidence that the copper in any of these
modifications is in the electronegative condition, and they all
dissolve in water to form solutions of the ordinary double sulphate.
An element like sulphur offers more facilities for diversity of
arrangement in the molecule than does the carbon in the car-
bonates, and it is probable that the different modifications of the
double sulphates are due to causes which may operate even in the
case of simple sulphates, for it has been found that these, in the
anhydrous and amorphous condition, may occasionally exist in two
modifications, according to the temperature to which they have

5 A 2

1428 PICKERING: THE CARBONATES OF

been heated. Sodium sixlpliate is an instance in jooint (Pickering,
Trans., 1884, 45, 686).

Nevertheless, there appear to be sulphate compounds analogous
to the j8-cupricarbonates. The compound with the formula
10CuO,SO3,4CaO,SO3, which is present in Bordeaux mixture
(PiclTering, Trans., 1907, 91, 1991), appears to be of such a nature;
it is violet, instead of blue, like the other basic sulphates, it
dissolves in a solution of dextrose, and ultimately oxidises it, with
the precipitation of cuprous oxide, whilst, when in solution in
sugar (before oxidation begins), it is absorbed by cellulose.

The cupricarbonates are evidently representatives of a very large
class of compounds, and one which certainly deserves further study,
for, not only do other organic acids form similar compounds, but
most other dyad metals seem to be able to act like copper.

The Colour of Co2}j)cr Salts.

The well-known change from blue to green of copper chloride
solutions on heating or concentration has been attributed to a
change in the ions by some, and by others to a change in hydration.
A similar change, however, has been noticed in two of the basic
carbonates here described, and also in one of the basic sulphates
(Trans., 1909, 95, 127), when these are in the solid condition, the
blue compounds becoming green when dehydrated, and reverting
to blue when rehydrated. A change in the ions cannot apply in
such cases.

Sui}i7?ja7'i/.

Besides the mineral azurite, 3CuO,2COo,H20j ^-^^d the ordinary,
and most stable, carbonate of copper, malachite, 2CuO,C02,H20, the
following carbonates have been isolated :

5CuO,2C02, a blue, bulky precipitate obtained by the precipita-
tion of copper salts by normal sodium carbonate. It loses its
carbon dioxide readily when warmed in the moist condition, or
when digested with a concentrated solution of sodium carbonate,
but takes up more carbon dioxide, forming malachite, when
digested with acid sodium carbonate.

5CuO,3C02, or a carbonate approximating thereto, is formed,
mixed with basic sulphate, by the precipitation of copper sulphate
with acid sodium carbonate. It is a light blue, dense solid, more
stable than the foregoing.

8CuO,3C02,6H2'0 is a rather dark blue carbonate, obtained by
the action of water on the double carbonate of copper and sodium.

Attempts to prepare SCuOjCOg and other more basic carbonates,
which have been said to exist, were not successful.

COPPER AND THE CUPRICARBONATES. 1429

All the basic carbonates are insoluble in water and in normal
sodium carbonate solution, but they dissolve slightly in aqueous
carbonic acid and in acid carbonates, a normal copper carbonate,
or a double carbonate of copper and the alkali metal, being formed.
The latter is obtained as a rather light blue, crystalline double salt
from such solutions, but it is probably a molecular compound of
the two carbonates, and, as it will not rcdissolve in the mother
liquor, and is decomposed by water, the solution yielding it must
contain some compound difTerent from, but probably isomeric
with, it: NaO'CO-OCuO'CO'NaO is suggested. In this compound,
termed the sodio-cupric carbonate, the copper is electropositive, but
has a colour thirty times more intense than the copper in copper
sulphate. When excess of normal sodium carbonate is added, the
copper becomes electronegative, and no longer reacts with ferro-
cyanide. The substance then present is what has been termed an
a-cupricarbonate, consisting of Na2Cu(C03)2 united with NaXOa,
but in which the copper is joined directly to the carbon atoms, and
is in a tetrad condition. It oxidises dextrose, and the constitution
suggested represents the presence of a loosely combined oxygen atom
explaining such a reaction. Excess of sodium hydroxide decom-
l^oses it, but a greater excess dissolves the basic carbonate thrown
down, to form a deep violet-blue solution of the )3-cupricarbonate,
which consists of NaoCu(C0;j)2 united with one or two molecules
of sodium hydroxide. This, too, oxidises dextrose, and also
combines with cellulose. It is stable in the presence of excess of
alkali, whereas the a-compound gradually decomposes, either into
the crystalline double salt or into malachite. The sodiocupric
carbonate decomposes in a similar manner, but generally into
malachite.

Incidentally, a new basic sulphate of the composition 15CuO,S03
has been obtained.

Addeiuhim. — Since this paper was communicated, some additional
evidence in favour of the constitution suggested for the i8-cupri-
carbonate has been obtained, but reasons have also appeared for
regarding it as probable that, in the presence of excess of alkali, the
introduction of hydroxide into the molecvile proceeds a step further
than w^as imagined, the oxygen atom combined with the copper,
as well as that combined with the carbon, becoming converted
into hydroxyls, and giving a substance containing the cuprate
group Cu(ONa)(OH). It is probably to the presence of this
grouping that the substance owes its violet colour and its action
on cellulose.

Haependek.

1-130 MITCHELL AND SMITH: CONSTITUTION OF

CLX. — Constitution of Hydroxy azo-compounds. Part II.
Action of Mercuric Acetate on Benzeneazonaj)hthols.

By Alec Duncan Mitchell and Clarence Smith.

At the present time, tlie balance of chemical and physical evidence
favours the view that hydroxyazo-compounds do not possess a
qiiinonehydrazone structure, and consequently contain a hydroxyl
group. The use of phenylcarbimide for the detection of this group
suffers from the disadvantage that different temperatures are
required for its reaction with j^ara- and with ortho-hydroxy azo-
compounds, the former yielding phenylcarbamates in hot benzene
(Goldschmidt and Rosell, Bcr., 1890, 23, 489), whereas similar
compounds can only be obtained from o-hydroxyazo-compounds in
the solid form at the ordinary temperature (Goldschmidt and Low-
Beer, Be/-., 1905, 38, 1098). By the use of mercuric acetate, this
defect is avoided, and in a previous communication (C. Smith and
Mitchell, Trans., 1908, 93, 842) it has been shown that o- and
j>-hydroxyazo-compounds of the benzene series react witB this salt
in boiling alcohol to form mercuriacetates, the number of mercuri-
acetate groups introdviced being equal to the number of unsub-
stituted positions ortho to the phenolic hydroxyl group ; for reasons
therein stated, this behaviour of hydroxyazo-compounds may be
regarded as evidence of their azo-structure.

It has been deemed advisable to apply the reaction to hydroxyazo-
compounds of the naphthalene series, for here uioholders of the
Cjuinonehydrazone formula have an argument which is not commonly
applicable to the benzenoid compounds, namely, that the con-
densation of naphthaquinones and aryl hydrazines gives rise to
the same substance as is produced by coujoling a-naphthols with
diazotised primary aromatic amines. Recent work, however, has
seriously damaged the validity of this argument for quinone-
hydrazone structure (Goldschmidt and Low-Beer, loc. rif. ; Auwers,
Ber., 1907, 40, 2154; 1908, 41, 403, 415; Noelting, Grandmougin,
and Freimann, Be/:, 1909, 42, 1377); Borsche, in particular, has
succeeded in condensing o-nitrophenylhydrazine and j^benzoquinone
to form o-nitrobenzeneazophenol, admittedly a hydroxyazo-compound
(Annalen, 1907, 357, 171). There seems to be little doubt, there-
fore, that the so-called naphthaquinonephenylhydrazones are in
reality azo-compounds. Their behaviour with mercuric acetate in
boiling alcohol supports this view, but the evidence is not as con-
clusive as could be desired, for although mercuriacetates are formed,
except in the cases of benzeneazo-a-naphthol and benzeneazo-

HYDROXYAZO-COMPOUNDS. PART H. 14'U

)S-r)aplitliol, wheuever the hydroxyazo-compound lias an unsub-
stitutcd position in the ortho- or jjara-position with respect to the
hydroxyl group, mercuriacetatcs arc still formed when there are
no such unsubstituted positions. Thus /3-benzeneazo-a-naphthol
forms a monomercuriacetate as is to be expected, but so also
do bisbenzeneazo-a-naplithol, 4-nitro-2-benzeneazo-a-naphthol, and
2-nitro-4-benzeneazo-a-naplithol. Only monomercuriacetates have
been obtained even with a large excess of mercuric acetate. The
formation of these mercuriacetates, however, was not entirely
unexpected, for since it has been shown (C. Smith and Mitchell,
loc. cit.) that mercuric acetate does nob react with the group
•No'CqHj, the mercuriacetate comjolex must have entered the
unsubstituted ring of the naplithalene nucleus in the preceding
comjiounds, and probably into position 8, for it is well known
that in naphthalene derivatives the peri-position is comparable
with the ortho-position in the benzene nucleus (C. Smith, Trans.,
1906, 89, 1505). Since all the jireceding hydroxyazo-compounds
are dei'ivatives of a-naphthol, the entrance of the mercuriacetate
group into position 8 would be in accordance with the rule pre-
viously established that the mercuriacetate complex enters the
nucleus in the ortho- or para-position with respect to the hydroxyl
group. Unfortunately, attempts to settle definitely the orientation
of the benzeneazonaphthol m&rcuriacetates have been unsuccessful,
for the replacement of the mercuriacetate complex by any group
or atom other than hydrogen has not been accomplished.

The hydroxyazo-compounds obtained by coupling diazotised
2:4: 6-tribromoaniline with a-naphthol, 2-nitro-a-naphthol, and
4-nitro-o-naphthol respectively, have been prepared and submitted
to the action of mercuric acetate in the hope that the formation
of mercuriacetates w-ould jDrove conclusively that the mercuriacetate
group has entered the unsubstituted half of the naphthalene
nucleus, but, owing to the extreme insolubility of the three
hydroxyazo-compounds in boiling alcohol, the existence of definite
mercviriacetates could not be established.

Benzeneazo-jS-naphthol does not form a mercuriacetate even when
fused with mercuric acetate. Benzeneazo-a-naphthol is oxidised
by mercuric acetate, yielding Witt and Dedichen's j8/3-dinaphthyl
derivative, Cr,H3-N.-Ci„H.(OH)-Ci„H,(OH)-No-C,H5; when the
j8-position is occupied by a nitro-group, the oxidation is prevented,
and 2-nitro4-benzeneazo-a-naphthol yields a monomercuriacetate in
the usual way.

1432 MITCHELL AND SMITH: CONSTITUTION OF

Experimental.

Mercuric Acetate and Benzeneazo-a-na'phtliol.

A solution containing 14 grams of mercuric acetate in 30 c.c.
of warm water and 5 c.c. of glacial acetic acid was added to
10 grams of benzeneazo-a-uaphthol dissolved in 700 c.c. of boiling
alcohol, and the mixture was heated on the water-bath for six
hours. The precipitate, filtered from the hot liquid, was washed
with alcohol and with hot water, and repeatedly extracted with
boiling dilute acetic acid until the filtrate was free from salts of
mercury. The residual chocolate-brown powder, washed finally
with alcohol and dried in the steam-oven, weighed 12 grams. It
blackened at 227° and melted and decomposed at 248 — 250°. The
substance was extracted with chloroform, whereby a residue of
finely divided mercury was left, and by evaporation of the solvent
a crystalline substance was obtained, green by reflected and red
by transmitted light, which melted and decomposed at 244 — 246°.
It was very sparingly soluble in alcohol or acetic acid and insoluble
in aqueous potassium hydroxide, dissolved readily in chloroform
or ethyl benzoate, and developed a bluish-purple coloration with
concentrated sulphuric acid, changing to indigo-blue on warming.
These properties indicated that the substance was Witt and
Dedichen's /3j8-dinaphthyl oxidation product of benzeneazo-
a-najDhthol (Ber., 1897, 30, 2660), and the identity was proved
by acetylating the substance by acetic anhydride and anhydrous
sodium acetate, and recrystallising the diacetate from toluene. It
melted at 263° (Witt and Dedichen's diacetate melts at 264—265°)
and gave the following numbers on analysis :

0-1503 gave 0-0595 HgO and 0-41S2 COg. C-74-8; H = 4-4.
^a(i^2G^i^4: requires C = 74-7; H = 4-5 per cent.

Mercuric Acetate and 2-Nitro-^-henzeneazo-a-na'phthol.

The hydroxyazo-compound was prepared by dissolving 3 grams
of 2-nitro-a-naphthol and 3 grams of potassium hydroxide in
1500 c.c. of water, cooling to 3 — 4°, and adding a diazotised solution
of 1-5 grams of aniline. After keeping overnight, the red pre-
cipitate was collected, washed with water, digested with dilute
acetic acid, whereby the red colour changed to orange-yellow, dried,
and recrystallised twice from benzene. 2-Nitro-^-henzeneazo-
a-naphtJiol crystallises in orange-red needles, melts at 164°, and
develops a bluish-red coloration with concentrated sulphuric acid.
It is readily soluble in hot benzene or glacial acetic acid, and

HYDROXVAZO-COMPOUNDS, PART II. 1433

dissolves in warm dilute potassium hydroxide, but is insoluble in
a cold concentrated solution :

0-1409 gave 0-3391 COo and 00495 IL,0. C = 65-6; H = 3-9.

0-1651 „ 20-4 CO. No^at 21° and 7G8 mm. N = 14-3.

CioHuOyNa requires C = 65-5; 11 = 3-7; N^llS per cent.

The acetyl derivative was obtained by heating the hydroxyazo-
compound for two to three hours with glacial acetic acid, anhydrous
sodium acetate, and acetic anhydride, pouring the solution into
dilute alcohol, and boiling for a short time until the dark, viscous
product had become red and granular. It was collected, washed,
dried, and crystallised from glacial acetic acid and twice from
benzene, from which it separates in fine, ruby-red prisms melting
at 173°:

0-1876 gave 0-4420 COo and 0-0619 HoO. C = 64-3; H = 3-7.
C13HJ3O4N3 requires 0 = 645; H = 3-9 per cent.

To a soliition of 1 gram of 2-nitro-4-benzeneazo-a-naphthol in
250 c.c. of boiling alcohol and 5 c.c. of glacial acetic acid was added
a solution of 2-5 grams of mercuric acetate in 5 c.c. of warm water,
containing a little acetic acid. The clear red solution was heated
on the water-bath for six hours, until the precipitate, which had
separated, did not increase in quantity. It was filtered hot, washed
with alcohol and with boiling water, and finally with hot dilute
acetic acid until free from soluble mercury compounds. After
being dried in the steam-oven, the mercuriacetate was obtained
as a lustrous, reddish-brown, crystalline mass, which blackened at
220°, but was not fused completely at 270°. Being practically
insoluble in all solvents, the substance could not be further purified.
The analytical data show that the product is a monomercuriacetate :

0-1099 gave 0-1601 COo and 0-0311 HoO. C = 39-7; H = 3-l.

0-2110 „ 0-0749 Hg." Hg = 35-5.

CisHisO^NgHg requires C = 39-2; 11 = 2-4; Hg=36-3 per cent.

Mercuric Acetate and fi-Benzeneazo-a-najihthol.

A solution of 9 grams of mercuric acetate in 25 c.c. of warm
water and 5 c.c. of glacial acetic acid was added to 3-5 grams of
j8-benzeneazo-a-naphthol dissolved in 200 c.c. of hot alcohol con-
taining a little acetic acid. The clear, dark red solution was heated
on the water-bath for nine hours, whereby a bulky, red precipitate
was formed, and then filtered when cold. By evaporating the
filtrate to 50 c.c., a further qiiantity of the substance was obtained.
The combined precipitates were washed with alcohol and with
boiling water, and extracted with hot dilute acetic acid until the
soluble mercury salts had been removed. The red residue was

1434 MITCHELL AND SMITH: CONSTITUTION OF

finally washed with boiling water and dried in the steam-oven.
The yield of the crude merciiriacetate was 6'5 grams or 91 5 per
cent, of the theoretical. The purification of the substance pre-
sented considerable difficulties, as it is very sparingly soluble in
the usual solvents except acetic acid. A pure product can be
obtained by the repeated precipitation of a solution in alcoholic
sodium hydroxide by acetic acid, but the following process, although
attended with great loss of material owing to the fact that the
mercuriacetate group is eliminated by boiling glacial acetic acid,
was adopted as being the quickest and least inconvenient. Five
grams of the finely powdered, crude mercuriacetate were added
to 100 c.c. of hot glacial acetic acid, and after a few minutes'
boiling the mixture was filtered into 100 c.c. of cold alcohol. The
red precipitate was collected, washed thoroughly with alcohol, and
dried at 110°; the weight was 3 grams.
fi-Benzeneazo-a-'na'phtJiol merciiriacetate,

CcH5-No-C,oH5(OH)-Hg-CO.Me,
is a brick-red powder, which darkens at 180° and melts with decom-
position at 208°:

0-3462 gave 0-5440 COo and 00819 H.O. C = 42-8 ; H = 2-6.
0-3198 „ 15-8 c.c. No"at 23° and 753" mm. N = 5-5.
0-3346 „ 0-1345 Hg. Hg = 40-2.

CjgHi^OgNgHg requires C = 42-6; H = 2-7; N=5-5;
Hg = 39-5 per cent.

The mercurichloride is obtained by adding a few c.c. of saturated
brine to a solution of 1 gram of the mercuriacetate in hot glacial
acetic acid. The red j^recipitate is collected and washed with acetic
acid, alcohol, and with hot water until free from sodium chloride.
It is a brick-red powder, which is practically insoluble in the
usual solvents; when heated it darkens at 130°, becomes black and
semifused at 200°, but is not completely melted at 270°.

Mercuric Acetate and ^-y'ltro-l-henzeneazo-a-vafhlliol.

The hydroxyazo-compound was prepared by adding a diazotised
solution of the requisite quantity of aniline hydrochloride to 9-5
grams of 4-nitro-a-naphthol and 11-5 grams of potassium hydroxide
dissolved in 200 c.c. of water. The purification was accomplished
in the same way as that of the isomcride previously described.

A-Xitro-2-henzeneazo-a-napJUhol separates from glacial acetic acid
in fine, dark red needles, melts at 180°, and is sparingly soluble in
hot alcohol, moderately in glacial acetic acid, and easily in hot
benzene. It gives a blood-red coloration with alcoholic jiotassium
hydroxide, and a bluish-red with concentrated sulphuric acid :

HYDROXYAZO-COMPOUNDS. PART II. 1435

0-2007 gave 0-4821 CO. and 0-0715 HoO. C = 65-5; H = 3-9.
CjoHjiOgNa requires C = 65-5; H = 3'7 per cent.

The acetyl derivative was obtained by heating 1-3 grams of the
substance and \b grams of anhydrous sodium acetate in glacial
acetic acid for six hours, pouring the sohition into dilute alcohol,
collecting the precipitate, and after washing it with alcohol and
water, recrystallising it thrice from glacial acetic acid. It separates
from this solvent in tufts of orange-red needles, and melts at 208° :

0-1205 gave 0-2837 CO. and 0-0420 HoO. C = 64-2; H = 3-9.
CjgHj.jO^Ng reqviix-es C = 64-5; H = 3-9 per cent.

The vwnumcrcuriacefate was obtained by adding a solution of
8 grams of mercuric acetate in 30 c.c. of warm water and 10 c.c.
of acetic acid to 3*7 grams of 4-nitro-2-benzcncazo-a-nap]ithol dis-
solved in 1250 c.c. of boiling alcohol. A marked darkening of the
colour was observed on mixing the solutions, and a red precipitate
soon began to separate. After being heated on the water-bath for
twelve hours, the liquid was filtered hot, and the precipitate was
washed with alcohol, water, and boiling dilute acetic acid until
the substance was free from soluble mercury compounds. After
being dried at 110° the product was extracted twice with 200 c.c.
of boiling benzene to remove any unchanged hydroxyazo-compound.
The residual mercuriacetatc was a red substance with the
appearance of amorphous phosphorvis. It melted and decomposed
at 221 — 222°, and was jjractically insoluble in the ordinary solvents.
It could not be obtained quite pure, but the analysis left no doubt
that the substance was a monomercuriacetate :

0-2837 gave 0-0995 Hg. Hg = 35-1.

Cj8Hi30,-N3Hg requires Hg = 36-3 per cent.

Mercuric Acetate and Bishenzeneazo-a-naylithol.

Seven grams of the disazo-compound dissolved in 400 c.c. of hot
alcohol were heated on the water-bath for six hours with a solution
of 13 grams of mercuric acetate in water containing a little acetic
acid. The precipitate was collected, washed thoroughly with hot
dilute acetic acid, with hot alcohol, and finally with hot benzene
to remove any unchanged bisbenzeneazo-a-naphthol. The dry crude
product, weighing 13-5 grams, was crystallised from phenol con-
taining a little alcohol. It was usually obtained as a dark brownish-
purple, crystalline powder, but on one occasion the mercuriacetate
separated in lustrous, black needles with a bronze lustre.

B ish enzeneazo-a-na'phthol mercuriacetate,

(CoH5-N2)2-C,oH4(OH)-Hg-C02-Me,
softens at 218°, and melts and decomposes at 235 — 238°. It shows

1436 CONSTITUTION OF IIVDllOXYAZO-COMPOUNDS. PART II.

tlic usual properties of a mcrcuriacetate, being almost or quite
insoluble in the common solvents, and having the niercuriacetate
groujj eliminated by acids; it gives with concentrated sulphuric
acid a reddish-violet coloration similar to that given by the original
hydroxyazo-compound :

0-2203 gave 0-3840 COo and 00582 HgO. C = 47-5; H = 2-9.
Co^HigOgN^Hg requires C = 47-2; 11 = 2-9 per cent,

2' : 4' : Q)'-T rih roinoA-iiit ro-2-h e7izeneazo-a-7iaphthol.

A solution of 8 grams of 2:4: 6-tribromoaniline in 45 c.c. of
alcohol and 30 c.c. of concentrated nitric acid was diazotised at 0°
by cold nitrous fumes, and added slowly to 3 grams of 4-nitro-
a-naphthol and 30 grams of potassium hydroxide in 1200 c.c. of
water. After remaining overnight, the precipitate was collected,
washed with alcohol, digested with hot dilute acetic acid, washed
with water, and dried in the steam-oven. By repeated solution in
hot nitrobenzene and precij^itation by alcohol, 3'5 grams of a
brilliant orange-red substance were obtained, which melted at
213 — 214°; the hydroxyazo-compound was finally recrystallised
from boiling amyl alcohol, from which it separates in orange-red
needles of the same melting point :

0-2388 gave 0-2534 AgBr. Br = 45-2.

CnjHv^OaNgBrg requires Br = 45-2 per cent.

2': 4': %'-Trihromo-4i-nitro-2-henzeneazo-a-naj)hthol is very spar-
ingly soluble in alcohol, benzene, and other low boiling solvents,
but dissolves readily in hot amyl alcohol, nitrobenzene, or ethyl
benzoate; it develops, with concentrated sulphuric acid, a cherry-
red coloration with a violet shade, and forms an acetyl compound
which melts at 186°.

2': 4' : Q)'-Trihro)nu-2-nitro-i-he7izen€azo-a-iiai)hiJiol.

A suspension of 15 grams of 2:4: 6-tribromoanilinc in 80 c.c.
of alcohol and 15 c.c. of concentrated nitric acid was diazotised at
0° by cold nitrous fumes, and the solution added to 5 grams of
2-nitro-a-naphthol and 5 grams of potassium hydroxide in 3 litres
of water, a solution of an additional 15 grams of potassium
hydroxide being added in small quantities from time to time in
order to keep the mixture alkaline. After remaining overnight, the
precipitate was collected, washed with water, digested with hot
dilute acetic acid, and finally boiled with alcohol to remove a little
2-nitro-a-naphthol. The crude product, weighing 13-3 grams, was
twice recrystallised from nitrobenzene, Avashed with alcohol, and
dried.

WALKER AND KRIERLK : THE AMYGDALINS. PART 1. 1437

2': 4': 6'-Tribromo-2-?nfro-A-he'ri:enea:o-a-iwph(/iol crystallises in
Orange-yellow plates and melts at 216°; it is less soluble than the
preceding isomeride, and gives an intense violet-red coloration with
concentrated sulphuric acid :

0-2225 gave 0-2353 AgBr. Br^450.

CicHgO^NgBra requires Br = 45-2 per cent.

Bis-2' : 4' : Q)' -t rib ronioh cnzcneazo-a-iurpli I hoi .

The production of this compound from a-naplithol and diazotised
2:4: 6-tribronioanilinc (2 mols.) was acconijilishcd as in the pre-
ceding preparation. The substance was purified by repeated
crystallisation from benzene, whereby it was ol^tained as a dark
maroon powder, which melted at 249 — 253° and gave a blue
coloration with concentrated sulphuric acid :

0-1984 gave 0-2685 AgBr. Br = 57-6.

C22Hj,|ONjBr|3 requires Br = 58-1 per cent.

In conclusion, the authors desire to express their indebtedness
to the Research Fund Committee of the Chemical Society for a
grant in aid of this investigation.

East London College.

CLXI. — The Amygdalins. Part I.

By J. Wallace Walker and Vernon K. Krieble.

In a previous communication by one of us (Walker, Trans., 1903, 83,
472) it was demonstrated that ^amygdalin is converted rapidly at
the ordinary temperature by a very small quantity of an alkaline
solution into a much more soluble substance, which yields on
hydrolysis by concentrated hydrochloric acid, not Z-mandelic, but
?*-mandelic acid. Althougli the new material was termed provision-
ally r-amygdalin, proof was wanting that it is even a homogeneous
substance, since it could not be obtained crystalline. The author
stated that it was still under examination, and consequently was
much surprised to find Dakin (Trans., 1904, 85, 1512) claiming
to have isolated it in crystalline form. It may be well therefore
to state here that its study had been continued ; that a very soluble,
crystalline substance had already been isolated from aqueous or
aqueous-alcoholic solution, which proved not to be r-amygdalin, since
it yielded mandelic acid possessed of a high Isevorotation ] that this

1438 WALKER AND KRIEBLE : THE AMYGDALINS, PART I.

substance yielded on fractional crystallisation ordinary or ^amygdalin ;
that the mother liquor on acid hydrolysis gave a large preponderance
of c^maudelic acid ; that the racemised solution, as was to be
anticipated, gave benzaldehyde and hydrocyanic acid with emulsin ;
and that the mandelic acid obtained from the racemised solution was
in no case absolutely inactive, but always contained a small excess of
the dextro-variety. There were, however, a number of questions
Avhich for a long time defied the attempts made to elucidate them, and
some of these we have only as yet been able to answer in part
satisfactorily.

Regarding the nomenclature to be adopted, we shall employ that
indicated in the former communication, considering it preferable to
the tso-amygdalin of Dakin or the neo-amygdalin of Tutin (Trans.,
1909, 95, G63), and designate ordinary amygdalin as ^-amygdalin,
since it yields /-mandelic acid and the isomeride which only differs
from it in yielding tZ-mandelic acid on hydrolysis as cZ-amygdalin,
leaving to their discoverer the task of assigning names to the similar
compounds which contain the different varieties of d- and Z-glucose.

In the former communication the simplest assumption was made
regarding the nature of the change induced in the molecule of
amygdalin by alkalis, namely, that it consists only in the racemisation
of the mandelic asymmetric carbon atom, although further change, for
example, that of a [i- into an a-glucoside, was not excluded. We have
reason now to conclude that a partial change of that nature does
occur during racemisation, and to a much greater extent on protracted
concentration of the solution, especially in presence of barium carbonate.
This of course complicates the problem, and renders it diiScult to
decide whether the small excess of dextro-acid which is invariably
found on hydrolysis represents a displacement of the equilibrium
in the transformation kevo^^dextro beyond the middle point. We
have proved, however, that the rotation of the racemised solution is
independent of the nature and of the concentration of the alkali, and
that the equilibrium-point is independent of temperature and of the
concentration of the amygdalin. In studying the fractional crystal-
lisation of the racemised solution, we find that tlie less soluble fraction
yields on hydrolysis mandelic acid containing 78 per cent, of the
laivo-variety, and that the more soluble fraction obtained by suitable
means from the mother liquor gives mandelic acid containing 75 per
cent, of the dextro-variety. These figures point to the presence of
the respective compounds {Zl + d)- and (3c/ + /) amygdalin, but their
rotations are not quite in conformity with this supposition, nor is the
behaviour of the second, when subjected to the action of emulsin, such
as we would expect from a compound having the composition
{Zd -h Z)-amygdalin. We are driven therefore to the conclusion that

WALKER AND KRIEBLE : THE AMYOnALIXS. PAFIT I. 1439

the second compound at least does not contain the substance wliich
we have termed (Z-amygdalin, and that the change induced in
Z-amygdalin by alkalis is of a much more complicated nature than has
been hitherto assumed.

Experimental.

The material employed throughout this investigation was Kahlbaum's
preparation. Analyses showed that it possesses the formula

aoH,70jiN,2H20,
and that when it is allowed to crystallise from aqueous solution the
air-dried material contains 3 molecules of water of crystallisation.
Its specific rotation, and that of its racemised solution, were
determined at different temperatures and concentrations. The
results contained in the following tables, as well as all that follow,
refer to the anhydrous substance.

Table I.

Table II.

1-

Amygdalin.

r-

Amygdulin

c:^18-54.

c = \7 •&'>'.

t.

[«]»•

t.

[a]...

20-5°

-38-0°

13-0''

-54-4

29-0

37-1

400

50-8

42 0

8-0"
16-0

c = 9-27.

35-8

■ 41-6°
40-1

23-0°
38-0

c = 8-9.

-52-8
51-0

20-0

39-3

c = 6-39.

25 0

38-8

26-0°

-52 4

28-5

38-3

400

36-8

c = 4-il4.

48-0

35-8

23-0"

-52-6

Table III.

l-Amygdalin. t = 28-5°.

c.

Mo.

c.

[«].

18 54

-37-1°

4-472

-39 0

9-27

38-3

2-236

39-4

6-71

37-8

These observations show a large and approximately equal variation
with temperature for both substances. The variation with con-
centration is much smaller in the case of ^amygdalin and negligible
for r-amygdalin.

TIte Equilibrium between Laevo- and Dextro-amygdalin. — Since the
two forms are not optical antipodes, there seems no reason to expect

1440 WALKER AND KRIEBLE : THE AMYGDALINS. PART 1.

that the equilibrium point should lie exactly midway between the
two, and even in the former communication it was noted, as lias
been confirmed by Dakin, that after complete hydrolysis of the
racemised solution with hydrochloric acid, the ethereal extract did
possess a slight activity, pointing to the production of a slight excess
of o?-amygdalin, although Liebig and Wiihler's amygdalinic acid gave
quite inactive raandolic acid. This has been fully confirmed in a
large number of subsequent experiments in which the hydrolysis was
performed both at the ordinary temperature and on the boiling-water
bath. If the equilibrium point, however, were not situated midway
between the two extremes, it is probable that by varying the
conditions of racemisation there would be a consequent displacement
of the equilibrium point. Of the four variable factors which may
influence the equilibrium point, namely, temperature, concentration of
the amygdalin, and the nature and concentration of the alkali, the
last two will be excluded if it can be shown that the reaction is purely
catalytic, and this was roughly done in the previous communication.
It has been considered advisable therefore to obtain more accurate
proof of the catalytic nature of the change. The alkali, however,
may also slowly hydrolyse both varieties of amygdalin to their respec-
tive amygdalinic acids, and, if it does so at unequal rates, but with a
velocity at all comparable to that of racemisation^ the dextro-variety,
if more rapidly hydrolysed by alkalis, as Dakin has shown (loc. cit.),
than it is by acids, would be continuously produced from the Irevo-.
It was therefore considered necessary to examine also the velocity of
the change of amygdalin into amygdalinic acid in alkaline solution,
although the facts recorded formerly, namely, that no ammonia could
be detected after racemisation, and that amygdalinic acid yields
r-amygdalinic acid, Avere strong evidence that alkaline hydrolysis
is not responsible for the excess of mandelic acid obtained. The
velocity of racemisation was observed in the 2-dcm. tube at 16°. The
first three solutions were prepared by adding 1 c.c. of the alkaline
solution to 25 c.c. of a 10 per cent, solution of recrystallised
^-amygdalin, the fourth by adding 1 c.c. of alkali to 50 c.c.

Table IV.
Catalyst, Barium Hydroxide, 1 c.c. added to 25 c.c.

[Oliserved

Time

rotation.

(in

minutes).

A-x.

K.

- 6 -86° (calculated

0

2-24

—

7-72

2

1-38

0-10.5

8-31

4

0-79

0-113

8-65

6

0-4.5

0-116

8 '88

9

0-22

0-112

9 09

14

0-10

0-168

WALKER AND KRIERLE : THE AMYGDALINS. PART I. 1441

Table TV {continued).
Catalysty Potassium Hydroxide. 1 c.c. added to 25 c.c.

Observed

Time

rotation.

(in minutes).

A-x.

K.

-6-86°

0

2-24

—

7-75

2

1-35

0-110

8-28

4

0-82

0-109

8-59

6

0-51

0-107

8-85

9

0-25

0-106

0-03

14

0-07

0-108

0-11

20

—

—

9-11

30

—

—

Catalyst, Lithium Hydroxide. 1 c.c. added to 25 c.c.

6-86°

0

2-24

—

7-72

2

1-38

0-105

8-25

4

0-85

0-105

8-63

6

0-47

0-113

8-86

9

0-24

0-108

9-08

14

0-02

0-146

9-10

20

—

—

Catalyst, Lithium Hydroxide. 1 c.c. added to 50 c.c.

7-00°

(calci

latctl)

0

2-24

—

7-43

2

1-81

0-0-16

7-88

4

1-35

0-054

8-21

6

1-03

0-056

8-54

9

0-70

0-0.57

8-88

14

0-36

0-056

9-11

22

0-13

0-073

9-24

38

—

—

9-25

58

—

—

The mean total change of rotation is 2*24°, and as the slight devia-
tions are well within the limit of experimental error this may be taken
as a measure of the total chemical action. The values of IC, calculated
by means of the unimolecular equation, are seen to be in satisfactory
agreement in experiments I, II, and III, whilst that in experiment IV
is just half value. Consequently all the alkalis examined racemise
amygdalin with the same velocity in equivalent solutions, and when
their concentation is halved the velocity of their action is also
reduced to half. These are the criteria for a catalytic action. It is
further important to note that, within the limits studied, the con-
centration of the alkali has no influence on the end point. As
these limits are, however, somewhat narrow, it was considered advisable
to extend them. In the following experiments, which Avere done at
25°, the volumes of water and barium hydroxide (1 c.c. =0*0122 gram

VOL. XCV. 5 B

1442 WALKER AND KRIEBLE: THE AMYGDALINS. PART I.

Ba(OH)„*) specified wore added to 20 c.c. of a 10 per cent, solution of
Z-amygdalin and the final rotation examined in the 1-dcm. tube :

C.c. water.
8
4
3
1

C.c. Imvyta.
1
5
6

Filial value of a„.

-3-35°

3-35

3-35

3-35

It is obvious that the concentration of the alkali is without in-
fluence. At 25° the velocity of racemisation was so great that the
change was almost complete by the time that the first reading could be
taken.

The velocity of hydrolysis of amygdalin to amygdalinic acid was
also examined polarimeti-ically, using a solution of sodium hydroxide
containing 0*1 gram-molecule in 50 c.c. For this purpose 10 grams of
reci'ystallised Z-amygdalin were dissolved in water containing five
equivalents of sodium hydroxide and diluted to 50 c.c, the change of
rotation being followed at 20-" in the 2-dcm. tube :

Table V.

Time.

On.

A-x.

K.

0

(-18-80°)

5-76

—

]4

19-40

5-16

0-00012

27

20-00

4-56

0 0001 3

77

21-40

3-16

0-00012

147

22-30

2-26

0-00010

297

23-54

1-02

0-00010

387

23-80

0-76

0-00009

1360

24-56

0-00

—

The initial reading, namely, —18-80°, obtained by plotting the
subsequent values and exteipolating, corresponds with a specific
rotation for anhydrous ?'-amygdalin of [a]^ —52-5°, which is identical
with that given in Table II, showing that the equilibrium point of the
reaction is the same even at this concentration of alkali as in the very
dilute. The values of /r, calculated from the equation for a
bimolecular reaction, are in good agreement, and it is evident that the
time taken is about 1000 times as long as that for racemisation, even
although the alkali is now more than 300 times stronger. It is
certain therefore that hydrolysis plays no part during racemisation
and is not responsible for any excess of c?-mandelic acid obtained on
acid hydroly.sis. Concurrent experiments to be desci'ibed later on
the fractional crystallisation of ?--amygdalin had led u.s to look upon
the dextro-variety as an extremely soluble substance compared with its
Isevo-isomeride, which could be isolated by fractional crystallisation from
the raccmised solution, and it seemed natural to associate the over-pro-
duction of the dextro-variety with its great solubility. If this were the

WALKER AND KllIEBLE : THE AMVQDALTNS. PART I. 1443

case we should expect to find that, by racemising in a very concen-
trated solution, a greater excess of the dextro-variety would be produced.
Consequently a series of experiments were made in which the con-
centration of the amygdalin varied from c = 17"657 to 4'414 and the
rotations of the resulting racemised solutions were observed. The
results are contained in Table II. As already stated they show that
the specific rotation of tho racemised solution is independent of the
concentration of the amygdaliu. Even more concentrated solutions of
r-amygdalin than these were produced by adding a small quantity of
baryta solution to solid amygdalin. After acid hydrolysis and
extraction with ether the mandelic acid obtained had always about the
same specific rotation, namely, +16°, indicating therefore about
15 per cent, excess of dextro-acid. A somewhat higher result was
obtained by the polarimetric] study of the hydrolysis of r-amygdalin.
The concentiation of anhydrous material was 9"44:3 and the hydrolyst,
hydrochloric acid (D = l'l). The change of rotation was followed in
the 2-dcm. tube at 40°.

Table VI.

Time

Time

(ill hours).

«D-

{in hours).

On.

0-5

-19-76°

22

+ 3-64'

]-5

19-7

41

12-22

2-75

18-64

66

16-74

5-75

15-48

89

18-70

17-0

-0-88

114

20-16

There was no further change on prolonged heating at the same
temperature. If inactive mandelic acid and dextrose be the sole
products of hydrolysis, the final rotation of the solution should be
+ 15-8°. The excess of dextrorotation observed is +4-4° which
corresponds with 21 per cent, excess of (i-mandelic acid, since the
specific rotation of the latter is +168° when dissolved in that strength
of hydrochloric acid. We have not yet been able to account for the
difference in the results obtained by the two methods except on the
assumption that the dextrose has also undergone some change.

The last factor which can influence the racemisation and produce
excess of the dextro-variety is temperature ; consequently, in order to
investigate this point, two experiments were performed, one at 50°, the
other at 100°, the amygdalin being racemised in each case with 10 c.c.
of the baryta solution. After complete acid hydrolysis they were
extracted with ether and a specific rotation taken of the dry acids. It
was found in both cases to be 16°. Consequently temperature has no
influence on the equilibrium point during racemisation. These facts,
all taken in conjunction, point to the conclusion that there is actually
a racemic compound in solution, and that the production of an excess

5 B 2

1444 WALKER AND KRIEBLE : THE AMYGDALINS. PART I.

of (/-mandelic acid from it is due to an inequality in tho rates of
hydrolysis of the two varieties by acid, accompanied by a slow
racemisation in that medium also. The experiments now to be
described on the fractional crystallisation of the racemised solution
indicate, however, that the material contained in it may not be of
such a simple nature.

The Partial Resolution of V- Amy gdalin. — This had been effected before
the last communication was published, but, owing to its incompleteness,
it was reserved for further study and only the statement made that
the racemic compound could not be obtained crystalline. Successive
crops of crystals had been obtained, however, either from aqueous or
alcoholic solution, but these, although showing a far greater solubility
in water than Z-amygdalin, were not constant in specific rotation, nor
had the latter nearly so high a value as that of the racemised solution.
Further, it was frequently found impossible to induce crystallisation at
all, but the syrup obtained on evaporation would dry up to a glassy
mass. It was found, however, that when a crop of very soluble crystals
was obtained, it yielded on recrystallisation almost pure ^-amygdalin,
and that, after a large amount of gummy material had been precipitated
from the alcoholic mother liquor by the addition of ether, the residue left
on the evaporation of the ether yielded, when hydrolysed with hydro-
chloric facid, a sample of mandelic acid meltiug at 120 — 125° and
showing a specific rotation of +99°. A partial separation had there-
fore been effected by fractional crystallisation and precipitation. In
a very I'ecent communication Tutin (Trans., 1909, 95, 663) has shown
that this may also be effected in the case of hepta-acetyl-r-amygdalin ;
})ut here also the separation is far from quantitative, for Tutin only
obtained 9 grams of crystalline material from 20 grams of y'-amygdalin
instead of the theoretical 16 '5 grams, and even that was evidently far
from pure hepta-acetyl-tZ-amgydalin. This is exactly on a parallel
with what we have observed in our very numerous experiments
on the fractional crystallisation of r-amygdalin. We always obtain
a considerable amount of uncrystallisable gum which yields excess
of cZ-mandelic acid on acid hydrolysis. At first it seemed probable
that this is due to some ^-amygdalin separating with the loss
soluble fraction, thus leaving an excess of the non-crystallisable
(Z-amygdalin in the mother liquor ; but subsequent experiments in-
volving a study of the action of emulsin on the different varieties,
and of the electrical resistances of the solutions before and after
evaporation, have led us to conclude that they may, according to the
treatment which they have undergone, contain 50 per cent, or even
more of something which is not one of the amygdalins. Our reasons
for concluding that it may to that extent have undergone an isomeric
change will appear in the description of a few of our experiments

WALKER AND KRTEHLE : THE AMYODALINS. PART I. 1445

bearing on that point. Assuming for tho present that the sohition
contains only /- and cZ-amygdalin in equivalent amounts, it is evident
from the specific rotations of I- and ?'-amygdalin, namely, - 39*3°
and -53" in 10 per cent, solution at 20", that tho specific rotation of
<Z-amygdalin must be — 66*7^ under the sarao conditions. Wo should
have therefore for (3? + f?)-amygdalin [a]i,-4:6"2° and for (3cZ + ^)-
amygdaliu [a]i, -59'9". The best method yet devised for conducting
the fractional crystallisation is as follows. After racemising 200
grams by baryta, the solution was saturated by carbon dioxide and the
barium carbonate removed by filtration. The filtrate was evaporated
to a syrup, and dissolved in a litre of 95 per cent, alcohol. After
being kept at 0" for several hours, 80 grams of crystalline material
were obtained. On drying over phosphoric oxide in a vacuum it lost
weight equivalent to two molecules of water of crystallisation. The
specific rotation of the anhydrous substance was c = 9-27, i = 28'5°,
a^, -8'65°; hence [a]o-46"6°. At 20", therefore, its specific rotation
must be -47' 7°, assuming that the temperature coefficient is the same
for this substance as for the other two. This value is in fairly close
agreement with that calculated above for a substance possessing the
composition of (3^ + rf)-amygdaIin, Ten grams of it were hydrolysed
with hydrochloric acid (D 1 *118), and the mandelic acid, after extraction
with ether, was converted into the barium salt (3'7 grams). Analysis
showed that it was almost pure barium mandelate. When dissolved in
water and diluted to 50 c.c, it showed a rotation of a^, - 6"8" at 20" in
the 2-dcm. tube. The specific rotation of pure barium ^-mandelate was
found to be [a] I, - 80 9° under the same conditions; hence the concentration
of la^vo-salt in excess in the above solution is t; = 6*8 x 100/80" 9 x 2 = 4'2.
Therefore 3'7 grams contain 2'1 grams of laevo-salt in excess and 1*6
grams of racemic salt or a total of 78*4 per cent, of the Isevo- com-
pound. That this crystalline material is mainly a definite compound
and not a mixture of I- and r-amygdalin was evident from the extreme
ease with which it dissolved in water. From the result of its hydrolysis,
however, it evidently contained a small quantity of free ^-amygdalin.
After being twice crystallised from water, it gave, on acid hydrolysis,
a sample of mandelic acid, showing the specific rotation [ajo - 142-5°.
It contained, therefore, less than 8 per cent, of (Z-mandelic acid. The
original mother liquor from the 200 grams of amygdalin was con-
centrated to a syrup and then extracted with 300 c.c. of a boiling
mixture containing one part of alcohol to three of ethyl acetate. The
residue, obtained after evaporation of the solvent, was dried over
sulphuric acid until constant in weight. It weighed 35 grams. As it
was non-crystalline, we had no criterion that it was a chemical
individual. It was therefore rerdissolved in 350 c.c, absolute alcohol,
and this solution kept for some time at about - 18", The crystalline

1446 WALKER AND KRIEBLE : THE AMYGDALINS. PART I.

material (10 grams) which separated was rapidly dried and transferred
at once to weighing bottles. These precautions are necessary, for at
a slightly higher temperature the crystals liquefy. The material in
the weighing bottles i-apidly melted, and was kept in a vacuum over
sulphuric acid until constant in weight. In this way it lost 35 per
cent, in weight, corre.spoading with 5"35 molecules of alcohol. The
material dried over sulphuric acid was employed for determining its
specific rotation with the following results : c = 5'9, t = 2d°, ^=l-dcm.,
Qi, -325°; hence [ajo — 55"1°. At 20°, thei'efore, its rotation will be
about -56°. Ten grams of it, when hydrolysed as above, yielded
4'35 grams of barium maudelate, showing the rotation c = 8-7, 1 = 2-dcm.,
ajy +7*25°. It therefore contained 75*7 per cent, of dextro-salt. Its
rotation, however, does not correspond with the value calculated
for (3ci + ^)-amygdalin. The alcoholic solution from which this modi-
fication of amygdalin was obtained yielded further crops of the same
material on evaporation.

Action of Emulsin on the Amygdalins. — When a solution of emulsin
was added to the racemised solution of amygdalin and the mixture
kept for several hours at 40° in a closed flask, it acquired a strong
odour of oil of bitter almonds. This was also observed by Dakin
{loc. cit.), but this qualitative observation is of no further value than
to afford proof that the solution still contains ^-amygdalin. A series of
comparative experiments has therefore been conducted quantitatively
to determine the action of emulsin on these different substances. The
emulsin employed was Kahlbaum's preparation. After the solutions
had been heated at 40 — 45° for twenty-four hours, the liberated hydro-
cyanic acid was estimated by the method described by Auld (Trans.,
1008, 93, 1277) and the dextrose by Fehling's solution. The former
we found far from satisfactory, as the end point is by no means sharp,
although accurate enough for comparative results. In the following
table are given the averages of several determinations.

Table VII.

0-2833 gram of 1-89 grams

substance rerjuired yielded of
of iVy^O-iodiue dextrose

(ill c.c). (in grams).

^Amygflalin 52-3 1*5

j-Amj'gdalin 2^-0 1-19

(3rf + 0-Amygdalin(?) 18-0 —

Since the values of iodine for the first two are very nearly in the
ratio 2 : 1, the conclusion seemed obvious that emulsin only liberates
hydrocyanic acid from the ^amygdalin present, and, as the amounts
of dextrose are approximately in the ratio 4 : 3, that it is only capable
of removing one molecule of dextrose fi-om the supposed cZ-amygdalin.

WALKER AND KRIEBLE : THE A.MVUDALINS. PART I. 144-7

If it contains (Z-araygdalin, the second substance ought to yield, on
partial hydrolysis by emultiin, cZ mandelouitrile glucoside. But Cald-
well and Courtauld (Trans., 1907, 91, 673) have pointed out that the
substance sambunigrin, isolated by Bourquelot and Danjou {Compt.
rend., 1905, 141, 598) from elder leaves, must be tZ-mandelonitrile
ghicoside ; consequently our solution ought to contain sumbunigrin.
That it does not contain that substance, however, was proved by the
fact that emulsin is unable to hydrolyse it, for no further change took
place on heating at 40' for forty-eight hours longer. We therefore
attempted to isolate the new substance by concentrating to a syrup
and extracting with ethyl acetate, but the residue left after evaporating
the ethyl acetate did not crystallise even after a long period. This
result led us to conclude that some further change than simple
racemisation had taken place in the amygdalin molecule ; accordingly,
another set of comparative experiments was made to determine
whether it is contemporaneous with, or subsequent to, racemisation.
The concentration of the emulsin was lower in these, so that it is
improbable that hydrolysis was carried as far as in the previous
experiments.

0*3 gram substance required of iV/SO-iodine :

(1) Racemiscd without heating 42 c.c.

(2) Racemised and dried for 4 hours on the water-bath 21 ,,

These results suggested an explanation of several difficulties, showing
as they do that a profound change takes place when the solution
is evaporated to dryness. They indicated a reason for the large
quantities of uncrystallisable material which we frequent'y obtained,
and pointed to a probable change in the rotatory power of the
racemised solution by protracted evaporation. Our early determina-
tions of this constant had shown considerable inexplicable divergences
from each other. There are three possible directions in which the
structure of the molecule may be affected by heating. It may suffer
an isomeric change in one or both of its dextrose radicles, it may lose
one dextrose radicle by hydrolysis, or it may be hydrolysed to
the ammonium salt of amygdalinic acid. That dextrose was not
liberated was shown by testing the evaporated material with Fehling's
solution. The result was negative. As none of the ordinary methods
of testing for the presence of an ammonium salt recommended them-
selves in this case, we finally decided to take the decrease in electrical
resistance of the solution as a measure of the amount of such hydrolysis,
and, at the same time, to measure the change in optical power. In the
cell which we employed the ordinary distilled water of the laboratory
had a resistance of 16,000 ohms at 19°, whilst a 5 percent, solution of

1448 WALKER AND KRIEBLE : THE AMYGDALINS, PART I.

the material employed, namely, C2oH270^^N,3H.,0, had a resistance of
2,444 ohms.

For the purpose of comparison 5 grams of the same sample
were boiled with excess of baryta until all the ammonia was expelled ;
then carbon dioxide and ammonia were passed into the solution to
precipitate all the barium as carbonate and give a solution of
ammonium amygdalinate. This was thoroughly boiled to expel dis-
solved gases, diluted to 100 c.c.,and found to be neutral in reaction and
free from barium. Its specific rotation was [a]o - 72°, and its resist-
ance 15 ohms. In the following three experiments 2*5 grams of
^-amygdalin were racemised with baryta, and, after precipitation of the
latter by carbon dioxide, were evapoi'ated on the water-bath for the
times specified. They were then diluted to 50 c.c, filtered, and their
electrical resistances and specific rotations measured. In the first
experiment 10 c.c. were hydrolysed by emulsin for twenty-four hours,
and the liberated hydrocyanic acid was titrated with iVySO-iodine,

Table VIII.

Time

(in hours). Ohms. [o]d (anhydrous). C.c. iV/50-iod.ine.
8 148 -61-0° 24

4 200 60 -C —

2 273 527 —

If we assume as an approximation that the resistance of a solution
of ammonium amygdalinate is proportional to its concentration, the
5 per cent, solution of that salt would evidently require to be diluted
to nearly ten times its volume to show a resistance equal to the first
of these. That is to say, 10 per cent, at most of the amygdalin has been
hydrolysed. When we examine the specific rotations, however, we
find that 61 -52/72 -52 = 9/20ths, or 45 per cent, has been changed,
assuming hydrolysis to be the cause. In the third experiment, con-
ditions are reversed, for thei-e practically no change has occurred in the
optical properties of the solution, although its resistance would indicate
5 per cent, of hydrolysis. Finally, without any assumption as to the
nature of the change, when the amount of hydrocyanic acid liberated
is compared with that produced under similar conditions from a race-
mised solution which has not been heated, we find that 66 per cent, has
been changed, for such a solution required 70 c.c. i\y50-iodine. We
must conclude, therefore, that the chief change which takes place on
protracted heating is not a hydrolytic one, but consists in some intra-
molecular transformation, a new isomeride of amygdalin being pro-
duced which probably bears to amygdalin the relationship of an
a-glucoside to a )8-glucoside, Our experiments are, however, not yet

ACTION OF THE GRIGNARD REAGENT ON PHTHALIC ESTERS. 1449

decisive as to whether the freshly racemised solution contains
fZ-amygdalin or not, but we are continuing the study of the subject.

Macdonald Chemistry and Mininu Building,
M<GiLL Univkhsity,

CLXII. — The Action of the Grignard Reagent on
Phthalic Esters.

By Yuji Shibata.

The action of the Grignard reagent on succinic esters results
according to A. Valeur {Bull. Soc. chim., 1903, [iii], 29, 683) and W.
Dilthey and E. Last {Ber., 1904, 37, 2640) in the production of tetra-
alkylbutandiols, OH-CRR-CH2-CH2-CRR-OH. I have recently studied
the action of the same reagents on phthalic esters, which are known to
have an analogous constitution to succinic esters, expecting that, in
this case also, glycols would be produced. It was found, however,
that this is by no means the case, derivatives of phthalide being
produced according to the following scheme :

^CO^R , oT?'A/r Y . n Ti ^CR'R'-OMgX ^ ^ „ ^CR.;\^

Generally, however, the reaction proceeds one step further, the
ketone group contained in dialkylphthalide, thus formed, combining
with another molecule of the Grignard reagent, and the resulting
compound decomposing in contact with water and producing the
anhydro-compound,* as shown below :

CR/. R'MgX /CR,' s /CRo'-\

CgH/ >0 -> C,H / ^ \o->C,H / " >0.

\-C0-/ and HoO \CR'{OH)/ \C(:R'y

The resulting compound is thus a derivative of phthalan (o-xylylene
oxide),

C.H,<CH^>0

(A. Ludwig, Ber., 1907, 40, 3062). The intermediate carbinol could
not be isolated.

* It appears likely that the dehydration is due to the action of the excess of the
Grignard reagent employed (compare F. W. Kay and W. H. Perkin, jun., Trans.,
1906, 89, 848, etc.).

1450

SHIBATA: THE ACTION OF THE

COoH

CO.,H

This difference in the action of the Grignard reagent on the esters
of succinic and phthalic acids may be easily explained by taking into
consideration the position of the carboxyl groups in the molecule of
the two acids.

As first pointed out by H. G. Bethmann {Zeitsch. j^hysikal. Chem.,
1890, 5, 409), certain properties of succinic acid correspond with the
following space formula, with its two carboxyl
groups in the ^ra?is-position, and the ease with
which succinic esters react with four molecular
proportions of the Grignard reagent and produce
glycols can be readily explained by adopting the
same formula, the two carboxyl groups in the
if-ans- position having no space influence on the
course of the reaction. la the case of phthalic
acid, however, only one ester group reacts with
two molecular proportions of the Grignard re-
agent, as already pointed out, and phthalide is formed as the inter-
mediate product. This must be considered as due to the steric
hindrance, or, in other words, to the effect of the cis-position of the
two carboxyl groups ia phthalic acid.

On the other hand, F. Ullmann and C. Schlaepfer {Ber., 1904,
37, 2003) obtained tetraphenyl-p-xylylene glycol,

HO-CPHg/ ^CPh2-0H,

by the action of magnesium phenyl bromide on dimethyl terephthalate,
the reaction being evidently quite analogous to that which occurs in
the case of succinic esters. It thus appears very probable that the
two carboxyl groups in terephthalic acid are in the trans-^tositiou.

These considerations enable us to discuss a little more fully than
hitherto the different space formuhe of benzene proposed from time to
time. The following may be regarded as their representatives :

Fig. I.

Fig. II.

Graebe {Bcr., 1902, 35, 51i6).

Saclisc (Ber., 1888, 21, 2530).

GRIGNAIID REAGENT OX PHTIIALIC ESTERS.
Fi<:. III. Fig. IV.

1451

Vaubel (/. pr. Chcm., 1891, [ii], 44', 137). Bacyer [Annalen, 1888, 245, 123).

Erleumeycr, jun. [ibid., 19ul, 316, -il).

Of these, neither III nor IV .appear to be in agreement with the
facts mentioned above, for, according to III (which is constructed by
laying six tetrahedra alternately above and below the plane formed
by their bases), phthalic esters, in reacting with the Grignard reagent,
should, like terephthalic and succinic esters, also give glycols, which
is not found to be the case, whilst in IV (which is constructed by
laying six tetrahedra on a plane hexagon), although the distance
between the para-positions is double that between the ortho-positions,
the two carboxyl groups in terephthalic acid have the same orienta-
tion, and must therefore, to a certain extent, have a hindering in-
fluence on each other in carrying out the Grignard reaction. This
again is not the case.

On the other hand, both I and II satisfy the main condition that the
two carboxyl groups in phthalic acid are in the cis-position, whilst
those in terephthalic acid are in the fra^is-position.

The choice between these two is not so easy to make. But, as will
be shown hereafter, I have obtained 1 : l-diphenyl-3-phenylenephthalan,

by the action of magnesium phenyl bromide on diethyl phthalate, this
compound being, no doubt, produced through the intermediate forma-

tion of the alcohol, CgH,\

— CPh,

C^O, as already indicated above

^CPh(OH)'

in a general way, the alcohol losing water from the group ICPh'OH.
Now, there are three possible ways in which water may be separated
from this group, according as the condensation occurs in the ortho-,
the meta-, or the para-position, thus producing one or other of the
following three double rings :

i>c r^n • 1 0 I

(A.) (B.) (C.)

Beferring to formulae I and III, which are to be preferred to

1452 SHIBATA : THE ACTION OF THE

formulaj III and IV, as already indicated above, we shall easily find
that formula II, proposed by Sachse, which is constructed in such a
way that the six tetrahedra are all rigidly combined with one another,
and in which the distance between the two free solid angles of any two
adjacent tetrahedra is too great for a third tetrahedron of the same
size to fit in, cannot account for the formation of a double ring (A),
and still less for the formation of (B) or (C).

In Graebe's model, on the other hand, any one of the three pairs of
tetrahedra, connected together through two of their solid angles, can
be rotated about the points through which it is connected with the
other two pairs, and in this way any two adjacent free solid angles
can be brought closer together until the distance between them is
equal to the length of an edge of the tetrahedron, and, with it, the
completion of a double ring (A) offers no difficulty.

If three pairs of tetrahedra are supposed to be rotated in the
manner described above, then, in the limiting case, model I would
coincide with model IV, and the distance between the two meta-posi-
tions would become equal to the length of an edge of the tetrahedron,
which would render the completion of the ring (B) possible. But, as
already explained, formula IV cannot be reconciled with certain facts,
and the formation of a double ring (B) must therefore be regarded as
improbable.

Again, even in the limiting case above supposed, the distance
between the two free solid angles in the para-position is too great for
the third teti'ahedron to fit in between them, so that the formation
of the double ring (C) is likewise improbable.

It thus appears that, of all the space formulae hitherto proposed,
that of Graebe, which is nothing but a representation in space of
Kekule'fi well known formula, is in best agreement with the facts,
and that i)-phenylene-l : 1-diphenylphthalane, to be described presently,

contains the double ring, | |^.

Experimental.
The Action of Magnesium Methyl Iodide on Diethyl Phthalate.

Diethyl phthalate (1 mol.), diluted with four times its volume of
absolute ether, was added gradually to magnesium methyl iodide
(4 mols.). After about twenty hours, the product was decomposed by
adding ice and dilute sulphuric acid, and the ethereal layer was well
washed and dried. On distilling off the ether, there remained a very
viscid, dark yellow oil with a faint odour, somewhat resembling that of
petroleum.

GRIGNARD REAGENT ON' PHTHALIC ESTKRS. 1453

At the ordinary temperature, the oil was so viscid that it did not
flow out of a vessel oven when held upside down, but at about 40*^ it
began to soften, and at about 79° became sufficiently mobile to be
transferred from one vessel to another. The oil was now subjected to
fractional distillation under 5 mm. pressure, when almost the whole of
it distilled between 140° and 155°, and the main poi^tion of it
at 145 — 146°, The distillate, which had a faint yellow colour
and a characteristic odour, gave the following results on analysis :

0-1911 gave 0-5805 CO. and 0-1249 HgO. C = 82-85 ; 11 = 7-31.

0-2083 ,. 0-6317 CO2 „ 01443 HoO. 0 = 82-71 ; H = 7-75.
Cj^HjoO requires C = 82-50 ; R =-- 7-50 per cent.

That this substance is 1 : l-dimeth]/l-3-methyle7ie2)hthalan,

was proved by the study of its oxidation product. On oxidising the
oil with chromic acid mixture, or by shaking with an acid solution of

potassium permanganate, dimethylphthalide, CgH^-<C_p^i^O, was

obtained :

0-1769 gave 0-4846 COg and 0-1000 HgO. C = 74-71; H=G-32,
CjqHjqOo requires C = 74-03 ; H = 6-23 per cent.

Dimethylphthalide has already been obtained by R. Kothe (Annalen,
1888, 248, 56) and H. Bauer {£er., 1904, 37, 735). The properties
of my sample agreed well with the description given by these authors,
except as to its melting point (69 — 71°), that given by Bauer being
68 — 69°, A similar difference in the melting point was also observed
in the case of dibenzylphthalide to be described later.

The existence of a double linking in 1 : l-dimethyl-3-methylene-
phthalan can be proved easily by the action of bromine on it, a
solution of bromine in chloroform, when added to one of the substance
in the same solvent, being decolourised at once.

The Action of Magnesium Phenyl Bromide on Diethyl Fhthalate.

Precisely as in the preceding case, diethyl phthalate and magnesium
phenyl bromide were mixed together in the proportion of 1 to 4
molecules, and the product was decomposed as before. After distilling
off the ether, there remained a yellow, viscous oil with an odour
resembling that of phenol, and showing a splendid green fluorescence.
The crude oil was subjected to steam distillation in order to remove
diphenyl, which was formed as a by-product. The oily residue was
then fractionally distilled under 8 mm. pressure, and it was found
that the first portion of the distillate, which solidified in scaly
crystals, consisted of diphenyl, which had escaped distillation with

1454 SHIBATA : THE ACTION OF THE

steaui. The main portion distilled between 280° and 295° as a
very viscous oil, and, on cooling, solidified as yellow crystals. These
were recrystallised from a mixture of chloroform and ether, when
small, colourless, glistening crystals melting at 194 — 195° were
obtained :

0-2240 gave 0-7390 CO2 and 0-1081 H^O. 0 = 89-97 ; H = 5-39.

0-2030 „ 0-6674 CO, „ 0-0972 H^O. 0 = 89-97 ; H = 5-37.

CagHigO requires C = 90-14 ; H = 5-24 per cent.

\ '.\-DipJienyl-^-phenylenepJdhalan, C^-H^-^C^p-.p XT^O, is very

readily soluble in chloroform, moderately so in benzene or ether, and
sparingly so in alcohol or light petroleum. Its solution decoloui-ises
neither bromine nor potassium permanganate. As already stated
in the introduction, this substance doubtless contains the ring,

1^, and a few other substances, such as cai'one and its derivatives.

are known to contain the same rinsr.

The Action of Magnesium Benzyl Chloride on Diethyl Phthalate.

On decomposing the reaction product by adding ice and dilute
sulphuric acid, a considerable quantity of a white, crystalline substance
was obtained. It was found to be insoluble in water, alcohol, ether, or
light petroleum, moderately soluble in benzene, and very soluble in
chloroform, and could therefore be conveniently recry»tallised fi-om a
mixture of chloroform and ether. When thus purified, it was obtained
in small, colourless needles melting at 207°. Its properties agreed
well with the description of dibenzylphthalide,

^6^4^>> — no ^^'

-co-
given by H. Bauer {Ber., 1905, 38, 240), except that this author gives
204° as its melting point. An analysis of the substance left no doubt
as to its being dibenzylphthalide :

0-1502 gave 0-4634 COg and 0-0795 H^O. 0 = 84-14 ; H = 5-92.
CggHjgOg requires 0 = 84-02; H = 5-79 per cent.

On distilling off the ether from the ethereal solution separated
from the aqueous layer and the crystals of dibenzylphthalide, a brown
oil was left behind, which solidified to a colourless, crystalline mass.
It was recrystallised from a mixture of chloroform and alcohol.
Brilliant minute crystals melting at 150*5° were thus obtained :

0-1957 gave 0-6412 OOg and 0-1071 H^O. 0 = 89-36 ; H = 6-12.
^■z'j^ii^ requires 0 = 89-64 ; H = 6-23 per cent.

GRIGNARD REAGENT OX I'lIIHAIJC ESTERS. 1455

1 : l-Dibenzyl-3-benzylidenephthalan, L\.ll^<^/^.^^.?■.i,!'£^0, thus

obtained, is very soluble in chloroform, moderately so in benzene or
ether, and almost insoluble in alcohol or light petroleum. When
oxidised with potassium permanganate, 1 : l-dibenzyl-3-benzylidene-
phthalan is readily converted into dibenzylphthalide. The action of
bromine on 1 : l-dibenzyl-3-benzylidenephthalan in chloroform or
carbon bisulphide solution is exactly the same as that on 1 : 1-dimethyl-
3-methylenephthalan, and takes place very easily at the ordinary
temperature.

The Action of Magnesium Ethyl Ilalides on rhthalic Esters.

The action of magnesium ethyl bromide and magnesium ethyl
iodide on diethyl phthalate and the action of magnesium ethyl iodide
on dimethyl phthalate wei-e studied, but in these cases no phthalan
derivatives were obtained, the only definite product isolated being
diethylphthalide.

On the usual treatment, a brownish-yellow oil, having a disagreeable
odour resembling that of onions, was obtained in each case, but on
fractional distillation under 12 mm. pressure, it gave no constant
boiling portion until the thermometer rose to 165°, when nearly the
whole of the remaining portion distilled over. This portion, after
refractionation, was analysed, with the following results, and was
proved to consist of diethylphthalide :

0-2444 gave 0-6754 COg and 0=^653 H,0. C = 75-37 ; H = 756.
CjoHj^Og requires C = 75*75 ; H = 7-43 per cent.

Diethylphthalide, C^H^'\_p/^f^O, has already been obtained by

R. Kothe {Annalen, 1888, 248, 67) and H. Bauer {Ber., 1904, 37,
735) ; the former i.solated it as an oil boiling at 210 — 214°/210 mm.,
whilst the latter obtained it in crystals melting at 54°.

In order further to identify the above product, I prepared its mono-
nitro-derivative according to the method described by Bauer. The
crystals obtained melted at 104°, and agreed in this and other respects
with the description given by Bauer.

Summary.

(1) In spite of the great analogy existing between phthalic acid
and succinic acid, the action of the Grignard reagent on phthalic
esters differs from that on succinic esters in producing derivatives of
phthalide, instead of glycols.

(2) Moi-e frequently, the reaction between the Grignard reagent

1456 ORTON AND JONES: PRIMARY INTERACTION OF

and phthalic esters proceeds one step further, with tlie production of
the derivatives of phthalan. 1 : l-Dimethyl-3-methylenephthalan,
1 : l-diphenyl-3-phenylenephthalan, and 1 : l-dibenzyl-3-benzylidene-
phthalan have thus been obtained.

(3) Various space formula} proposed for benzene are discussed
from the point of view of the experimental results obtained in this
investigation, and it is shown that Graebe's model, which represents,
spatially, Kekul6's ring formula, accounts for the facts in the most
satisfactory manner.

The Chemical Institute of the College of Science,
Impeuial Univeesity of Tokyo.

CLXIII. — Primary Interaction* of Chlorine
and Acetanilides,

By Kennedy Joseph Previt6 Orton and William Jacob Jones,

It has often been suggested that the primary union of reagents
with anilines and anilides is through the nitrogen atom, subsequent
changes (possibly intramolecular) leading to the formation of the
substituted aniline or anilide. In the case of chlorine (or bromine),
such a primary product may be a compound in which the nitrogen
is quinquevalcnt, or the chloroamine with tervalont nitrogen formed
from the first:

yAc

Ar-N<!J -^ Ar-NCI-Ac + HCl.

\

That the chloroamine is not, in a strict sense, an intermediary
in the chlorination of anilides follows from Armstrong's discovery
that the presence of hydrochloric acid is essential for the conversion
of the chloroamine into the isomeric chloroacetanilide. This
observation gives a strong 'prima facie case for the view that the
complex in which the nitrogen is quinquevalent is the actual
intermediary (compare Orton, Proc. Boy. Soc, 1902, 71, 156). It
is difficult to understand, however, why hydrochloric should in that
case be the only acid capable of forming with the chloroamine a
salt in which the chlorine can migrate to the nucleus.*

* The more recent work of Blanksma and the view.s expressed by Acrce will be
referred to in a subsequent paper.

CHLORINE AND ACETANILIDES. 1457

In the course of some experiments on the interaction of various
acids (hydrochloric, hydrobromic, sulphuric, hydrofluoric, etc.) with
chloroainines, it was found that chlorine could always be detected when
liydrochloric acid, but not when one of the other acids, was present.
This fact has led us to investigate the interaction of hydrochloric
acid and chloroaniines, and its converse, the primary interaction of
chlorine and anilides.

It has been found that an equilibrium :

Ar-NH-Ac + CI, ^ Ar-NCl-Ac + HCl,

is always rapidly established in the first instance, and is then slowly
disturbed by the formation of the chloroacetanilide.*

The comi^osition of the system when in equilibrium is determined
by measuring the free chlorine, by aspirating a small volume of
air through the solution. Comparison of the amount of chlorine
evolved in the air current with that given off by standard solutions
of chlorine in the same solvent allows of a measurement of the free
chlorine in the solution. The details of the method are given in
the experimental part.

Our results show that the composition of the system in
equilibrium depends (apart from temperature and concentration
of the components) on various factors, namely, the solvent, the
nature of the acyl group, and the nature and number of the
constituents in the benzene nucleus. Unsvibstitvited acetanilide is
so rapidly chlorinated that it is not possible to determine the
composition of the system by this method.

Solvent. — As solvent, it is only feasible to use acetic acid, or
mixtures of acetic acid and water; alcohols or acetone are attacked
too rapidly by the chlorine. Although carbon tetrachloi'ide and
chloroform cannot be used for quantitative measurements, owing
to the insolubility of the hydrochloric acid, it is of interest to
note that when a gram-molecular proportion of this acid in aqueous

* "We have not discussed iu this paper the possibility that the hydrolysis of
ehloriue by water precedes the formation of chloroainine, or vice vcrsd, that the
liydrolysis of the chloroamine precedes the formation of chlorine :

Cl + HaOZTHCl + HClO ; KC10 + Ar-NH-Ac:mAr-NCl'Ac + H.p.

Since in our numerous experiments nothing has appeared to require such inter-
mediate reactions, we have chosen the simpler view that chlorine can directly
interact with anilides, and hydrochloric acid with chloroaniines. It may be
mentioned that our study of chlorine solutions show that, although the small
amount of hydrolysis of chlorine in aqueous solution first determined by Jakowkin
{Zeitsch. physikal. Cnem., 1899, 29, 626) can be readily recognised by our aspiration
method, there is no indication of such a hydrolysis in solutions of acetic acid above
50 per cent. Furthermore, it is precisely in these circumstances when the
hydrolysis of the chloroamine is least, namely, in glacial acetic acid, that the
reaction with hydrochloric acid is most extensive.

VOL. xcv. 5 c

1458

ORTON AND JONES : PRIMARY INTERACTION OF

solution is shaken with a solution of acetylchloroamino-jj-chloro-
benzene in carbon tetrachloride, 2>chloroacetanilide, which is very
slightly soluble in that medium (100 c.c. dissolve 003 gram at 15°),
begins directly to separate.

The proportion of water has a very marked effect on the com-
position of the system. In glacial acetic acid (99'5 per cent.), at
a concentration of 0'025 gram-molecule per litre, the right-hand
side of the equation is not detectable. On adding water, reaction
between the chlorine and the anilide takes place, until with 50 per
cent, of water, in the case of the majority of anilides, the system
consists, when the concentration is 0*025 gram-molecule per litre,
nearly completely (98 per cent.) of chloroamine and hydrochloric
acid (see table I) :

Table I.

Percentage of chlorine combined in

(i) 65% (ii) 75% (iii) 90% acetic acid.

jo-Chloroacetanilide — 94 —

/?-Nitroacetanilide 68 39'5 11

2 : 4-DichloioacetainUde over 95 80 34

2 : 4-Dichloroformanilide over 95 835 32

2 : 4-Dichlorobenzanilide 89 62 14

s-Tribromoacetanilide over 95 86 43

The nature of the equilibrium, as well as the composition of the
system, is also affected by the composition of the solvent. In 90 per
cent, acetic acid a constant is given by the equation :

]^— /■gchloroamine <^ ^hydrochloric acid\ //^chlorine ^ ganilideN

the concentrations being expressed in g^-am-molecules per litre ;
but with a higher proportion of water, for example, 75 per cent,
acetic acid, this equation gives no constant (see table III) :

Table II,
Values of equilibrium constants in 90 per cent, acetic acid

K.

2 : 4-Dichloroacetanilide 0'17

2 : 4-Dichloroformanilide 0"21

2 : 4-Dichlorobenzanilide 0*028

;o-Xitroacetanilide 0'015

s-Tribromoacetanilide 0-39

CHLORINE AND ACETANILIDES.

1459

Table III.

2 : 4-Dicliloroacetanilide in 75 per cent, acetic acid at 15°. The

equilibrium constant, K = 6-6, is calculated on the numbers enclosed

in a rectangle :

"Chlorine free" expressed
as a percentage of the

Conceiitra
molccul

;ion
sspc

in gram-
r litre.

I'iilorine carried over by

tlie air current expressed

in c.c. i\710-solution.

maximum amount of

chlorine obtainable

from the system.

Chloroaiiiinc.

chloride.

Found.

Calculated.

Found.

Calculated.

0 025

0-025

2x0-025

0-025
0-025
0-025

1-06
1-15
1-88

1 -54
1-54
2-12

19-3
20-9
34-3

28-0
28-0
38-7

3x0-025
3x0025

0-025
0-025

2-51
2-5

—

45-5
45-7

5x0025

0-025

3-47

3-02

63-2

55-0

In 65 per cent, acetic acid, although a constant is not given by
the above equation, the equilibrium is expressed by the equation :

J^' _ /gcliloroaniine ^ (p- hydrochloric acidV/gClilorine ^ gaiiilideX

as is illustrated in table IV :

Table IV.

j>Nitroacetanilide in 65 per cent, acetic acid at 15°. K' = 0-093.

"Chlorine free" expressed

as a percentage of the

maximum amount of

chlorine obtainable

from the system.

Concentration in gram-
molecules per litre.

Hydrogen
chloride.

Chlorine carried over by

the air current expressed

in c.c. iV/10-solution.

0-025
3x0-025
3x0-025

Chloroamine.

0-025
0-025
0-0-25

Found.

2-57

15^1 \
5-49 f

Calculated on
equilibrium.
(1)K (•2)K'
3-54 2-44

Found.
32
68-1

Calculated on
equilibrium.
(1)K (2)K'
44-2 30-4

The value of K' for 2 : 4-dichloroacetanilide in 65 per cent, acetic
acid is 4-47, and for 2: 4-dichlorobenzanilide, 1-06. In 75 per
cent, acetic acid, the hydrochloric acid is only partly ionised,* and
hence the equilibrium is not represented by either equation alone.

Acyl Grouj). — The results (table I) appear to show that the

* These facts would appear to indicate that in dilutions of acetic acid down to
90 per cent, acetic acid, hydrochloric acid, at the concentrations used, 0-006
— 0-1 gram -molecule per litre, is not appreciably ionised, whilst in 65 per cent,
acetic acid, ionisation is complete ; at intermediate concentrations of acetic acid,
for example, 75 per cent., hydrochloric acid is partly ionised between the limits of
the concentrations just mentioned.

1460 ORTOX AND JOXES : TRIMARY INTERACTION OF

acyl group has a steric effect on the equilibrium, thus the largest
amount of chlorine is free when the benzoyl group is a constituent
of the anilide.

Siihxhfucnfs in the Ben-ene Nucleus. — It is remarkable that the
presence of two bromine atoms in the ortho -position with respect
to the imino-group so greatly diminishes the proportion of free
chlorine in the system (chlorine combined in 75 per cent, acetic
acid = 86 per cent.). Equally remarkable is the effect of the nitro-
group in the para-position (chlorine combined in 75 per cent, acetic
acid = 39'5 per cent.). Measurements made with 2>chloroacet-
anilide, which, owing to the rapidity of chlorination, are less exact,
show that it is the nitro-group, and not the position occupied, that
is singular. In the case of ^j-chloroacetanilide, the chlorine
combined is greater than in the case of 2 : 4-dichloroacetanilide,
namely, 94 instead of 80 per cent, (table I).

Effect of Acids, Chlorides, and, Sodium Acetate on the
Equilibrium. — Whilst the addition of sulphuric acid alone to a
solution of a chloroamine does not cause the appearance of chlorine,
the addition to the system :

Ar-NH-Ac-FCl2 :^ Ar-NCl-Ac + HCl,

increases slightly the proportion of uncombined chlorine. Thus,
using 2 : 4-dichloroacetanilide, the following results are obtained
in 75 per cent, acetic acid. When the concentration of the anilide
and chlorine are each initially 0"025 gram-molecule, and the
sulphuric acid l"5x0"025, the percentage of chlorine free is 23,
whereas, in the absence of sulphuric acid, the percentage of chlorine
free is 20.

The presence of potassium chloride (at equivalent concentrations)
has very much the same effect as sulphuric acid; thus the chlorine
free in 75 per cent, acetic acid is raised from 20 to 24 per cent.

The addition of sodium acetate to the system has, on the other
hand, a very marked effect. Thus, in glacial acetic acid, no
chlorine is combined, but in the presence of one molecular pro-
portion of sodium acetate only 50 per cent, remains free. In 75
per cent, acetic acid, the chlorine free is similarly reduced from
20 to 10-7 per cent.

Effect of Temperature. — The effect of raising the temperature to
20° is to displace the equilibrium in favour of the anilide and
chlorine. In 90 per cent, acetic acid, using dichloroacetanilide, the
chlorine combined at 20° is 28 per cent., whilst at 15° it is 34 per
cent, (see table V) :

I

CHLORINE AND ACETANILIDES.

U6l

Concentration in ftrani-
niolecnles per litre.

Hydrogen

chloride. Chloroauiine.

0-025 0 025

3x0-025 0-025

4x0-025 0-025

Table Y.

Chlorine carried over by

ihe air current exjiressed

in c.c. aNyiO-solution.

At 15".
3-1
4-41
4-49

At 20"
3-45
4-7
4-8

'Clilorinc free" expressed

as a percentage of the

inaxinmm amount of

chlorine obtainable

from the system.

At 15. At 20"

66 72

93 98

95 100

Experimental.

The method of measuring the free chlorine in the solution is
based on the fact that a given volume of air, drawn through a
solution of a gas, abstracts a quantity of gas which is proportional
to the amount initially dissolved, provided that the air is saturated
with the gas; or, in other words, the partial pressure of the gas
in the air in contact with the solution is at a maximum. When
the aspiration is at such a rate that this condition is attained, the
quantity of gas abstracted is independent of the rate of aspiration.

Perman (Trans., 1895, 67, 868; 1898, 73, 511; Proc Roy. Soc,
1903, 72, 72) has devised methods for investigating this
phenomenon, and has made a special study of solutions of
ammonia.*

The apparatus which we have used in aspirating chlorine solutions
was arranged as follows : Drechsel bubblers, containing the chlorine
solution and the potassium iodide, together with the aspirator,
which was of rather more than two litres capacity, were placed in
a large constant-temperature bath. Since light accelerates greatly
the attack of chlorine on acetic acid, especially when diluted, the
bath was kept in a darkened room and carefully shielded. Inasmuch
as the volume of air aspirated through the bubbler was determined
by measuring the volume of water drawn from the aspirator, which
was always filled to a given mark on the capillary tube connecting
it with the second potassium iodide bubbler, no correction of the
volume for the varying atmospheric pressure was necessary in our
comparative experiments. The volume of " vacuum " brought in
contact with the chlorine solution was constant. The air drawn
through the chlorine solution was freed from dust and water
vapour.

Since the extraction of chlorine would displace the equilibrium
of the system, it was essential that only as small a proportion as

* Other investigations which bear on this subject have been made by Gahl
{Zeitsch. physikal. Chcni., 1900, 33, 178), Cans (Zeifsch. anorg. Chan., 1900, 25,
236), and ]\IcLauchlan {Zeitsch, physikal. Chem., 1903, 44, 600).

1462 ORTON AND JONES : PRIMARY INTERACTION OF

could be measured should be removed. Trials have shown that the
use of 100 c.c. of solution, which completely filled the bubbler, and
250 c.c. of aspirated air permit a sufficient accuracy. Titrations
of the iodine set free in similar experiments only deviate by
+ 0025 c.c. T/lO-thiosulphate; but even then, if the solutions
contain very little free chlorine, the error may amount to some
units per cent.

The quantity of chlorine extracted was ixsually less than 5 per
cent, of that present in the solution, but in the most unfavourable
cases as much as 10 per cent, of the free chlorine must be extracted
in order to obtain a trustworthy measurement.

The 250 c.c. of air were aspirated through the solution in
two and a-half minutes. The flow could be very accurately regulated
and kejDt constant during the aspiration by a glass tap, to which
a long arm used as an indicator was attached. Reduction of the
time to one and a-half minutes still permitted the air to become
saturated in the case of the more dilute acetic acid solutions with
the form of bubbler used by us, but scarcely in glacial or 90 per
cent, acetic acid.

In the experiments, the great difficulty lay in preventing change
in the concentration of the standard solutions of chlorine diiring
the manipulations. These solutions were made up in glacial acetic
acid, and were transferred to a burette (100 c.c. capacity),
standardised, and the appropriate volume then run into the bubbler,
which contained the anilide dissolved in glacial or more dilute
acetic acid, previously brought to 15°. The diluted acetic acid
was made up as volumes per cent., and the change of density
allowed for, so that the volume of solution in the bubbler was
100 c.c. The mixture was kept in the bath five minutes before
aspiration. The jirocedure when chloroamine and hydrochloric
acid were used was far simpler. The acid was added last to the
solution of chloroamine in the bubbler; when the medium was
glacial acetic acid, hydrochloric acid was necessarily in the form
of a concentrated standard solution, about 20 per cent., the small
volumes, in some cases less than 0'2 c.c, being measured in a
standard burette gradviated to 001 c.c. The following example
shows the extent of the agreement found, on the one hand, when
the system initially consists of chlorine and anilide, and, on the
other, of chloroamine and hydrochloric acid ; using 2 : 4-dichloro-
acetanilide in 50 per cent, acetic acid, the chlorine combined in
the first case was found to be 97 per cent., and in the second 98 per
cent, (see also table VT).

Aspiration of Standard Chlorine Solutions. — The standard solu-
tions of chlorine in various dilutions of acetic acid were made up

CHLORINE AND ACETANILIDES.

1463

with chlorine freed from hydrochloric acid and water, and used
immediately on preparation. It was shown, however, that con-
siderable proportions of hydrochloric acid, up to a quantity
equivalent to eight times that of the chlorine, did not affect the
amount of chlorine evolved in aspiration. The curves show that

160

140

120

100

80

GO

•^

40

20

/

/

-y-

m4^

/

0 fj 10 15

Tilre of chlorine carried over by 250 c.c. of air.

the chlorine abstracted is proportional to the quantity present in
the solution for concentrations of acetic acid above 50 per cent.,
that is, the solutions obey Henry's law. For aqueous solutions of
chlorine this is not the case; an approximation to Henry's law is
only found for concentrated solutions above 0475^ ; owing, doubtless,
to the effect of the hydrolysis of the chlorine : Clo + HjO ^^
H* + Cr + HCIO.

The rate of attack of chlorine on acetic acid is very slow in
the dark, but becomes more rapid as water is added. It is never
sufficient to interfere materially with the accuracy of our experi-
ments. Thus the titre of 10 c.c. of a standard solution of chlorine
in 75 per cent, acetic acid fell in seventy-five minutes only froin
25 to 24-95 c.c. of i\750-thiosulphate.

l-iG-i PRIMARY INTERACTION OF CHLORINE AND ACETANILIDES.

Table VI.

The following table shows a typical series of numbers obtained
with 2 : 4-dichloi'oacetaniIide in 90 per cent, acetic acid. K = 0'166.

Concentration in oram-
molecules per litre.

Chlorine carried over by

the air current expressed

in c.c. AViOsoIution.

" Chlorine free " expressed

as a i)ercentage of the

maximum amount of

chlorine obtainable

from the sysrem.

Hydrogen
chloride.

Chloroamine.

Fiiund

Calculated.

Found

Calculated.

0 025
0-025
0-025
0-025
Jx 0-025

0-025

0 025

2 X 0-025

2x0-025

ix 0-025

3-10
3-12
3-91
4 04
0-77

3-34
3-34
4-16
4-16
0-83

65-8
66-3
83-0
85-8
65-4

70-9
70-9
88-4
88-4
70-9

2x0-0-25

0-025

14-161

—

88-4

—

3 x 0 025

0-025

4-39

4-38

93-2

93 0

3 X 0-025
4x0-025

0-025
0-025

4-41
4-49

4-38
4-48

93-7
95-3

93 0
95-0

Chlorine.
0-025

Anilide.
0-025

3-30

3-34

70-1

70-9

Our thanks are due to the British Association for a grant which
has partly defrayed the cost of this investigation, and to Mr. W. C.
Evans, B.Sc, who carried out most of the preliminary experiments.

University College of North Wales,
Bangor.

THE CONVERSION OF PINENE INTO SOBREROL. 14G5

CLXIV. — Tlic Conversion of Pinene into Sohixrol.

By George Geuald Henderson and Wilfred James Stevenson

Eastburn.

As stated in a former communication, sobrerol can be obtained by
oxidising pinene with aqueous mercuric acetate in the cold (Henderson
and Agnew, Trans., 1909, 95, 289). The pinene used for the experi-
ments quoted in that paper showed only a small degree of optical
activity, and, naturally, it was the inactive modification of sobroi'ol
that was produced, the mixture of d- and ^-pinene yielding an optically
inactive mixture of d- and Z-sobrerol. At the suggestion of Professor
Pope, we liave now examined the behaviour of d- and ^pinene towards
mercuric acetate.

The fZ-pinene, obtained from Burmese oil of turpentine, was distilled
in a current of steam, dried over potassium hydroxide, and fractionated
with the aid of a " pear " fractionating column. The portion which
distilled at 155 — 157° was used for oxidation ; it was found to have
df 0-8599 and [aj^' Sl-P. The ^-pinene was obtained from French
oil of turpentine, and purified in a similar manner The portion used
for oxidation distilled at 156° ; it was found to have df^ 0-8606 and
[ajf,' —39 "2°. Fifty grams of each specimen were oxidised with 350
grams of mercuric acetate dissolved in 1500 c.c. of water. After
agitation for several days, the solutions were filtered, and the filtrates
thoroughly extracted with chloroform. The chloroform extracts,
after being washed with aqueous sodium carbonate and dried over
anhydrous potassium carbonate, were heated until the chloroform was
expelled, and there remained viscous, brown residues, which solidified
on standing, and were purified by repeated crystallisations from
benzene. In each case the product obtained was the inactive modifi-
cation of sobrerol melting at 131°; in alcoholic solution, neither
product exhibited any optical activity. Another specimen of pinene
from American oil of turpentine, much more strongly dextrorotatory
(fZ'f' 0-8609, [aju 13-9°) than that used in our former experiments,
was also oxidised with mercuric acetate, and yielded again inactive
sobrerol.

It is therefore clear that optical inversion occurs when d- or Z-pinene
is converted into sobrerol by the mercuric acetate method as described.
However, the formation of sobrerol by this method is apparently not
a case of simple oxidation of pinene. In all probability the first step
in the process is the formation of an additive compound of pinene and
mercuric acetate, which, under the conditions of the experiment,
undergoes a subsequent change into sobrerol.

VOIi. XCV. 5 D

14CG PHILIP AND GARNER: INFLUENCE OF VARIOUS SODIUM

The comparative ease with which sobrei'ol can be obtained by means
of mercuric acetate suggested the application of that reagent to test
for the presence of pinene in Russian and in Swedish oil of turpentine.
A specimen of the Russian oil was washed with aqueous sodium
cai'bonate, distilled with steam, dried over potassium hydroxide, and
fractionated with a " pear " column. A small fraction distilled at
156 — 157°, but the bulk of the oil had a higher boiling point. This
fraction was found to have d'-^' 0'8598 and [a]'o° 284°, and on treat-
ment with mercuric acetate by the method described above it gave a
satisfactory yield of inactive sobrerol ; hence the specimen of
Russian oil of turpentine undoubtedly contained a small proportion of
rf-pinene.

A sample of Swedish oil of turpentine was purified in a similar
manner, and on distillation yielded a fairly large fraction boiling below
150° and a very small fraction boiling at 154 — 157°, while the bulk of
the oil had a higher boiling point. The fraction which distilled at
154 — 157° was taken for oxidation ; it was found to have d^t 0*7834
and [aj'u', 5 •7°. It did not react with mercuric acetate nearly so
easily as the specimens of pinene, and only a small quantity of an
oxidation product was extracted by chloroform. This product appeared
to contain no sobrerol, and we therefore conclude that the Swedish oil
of turpentine contained no pinene, or, at the most, an exceedingly
small proportion.

"We take this opportunity of expressing our thanks to Professor
Pope for kindly supplying us with several specimens of pinene from
different sources.

Chemistry Department,
The Glasuow and West of Scotland Technical College.

CLXV. — Influence of Various Sodium Salts on the
Solubility of Sparingly Soluble Acids. Part II.

By James Charles Philip and Frederick Basil Garner.

In a previous paper (Trans., 1905, 87, 987) attention was directed to
the fact that the solubility of a sparingly soluble acid is markedly
increased in presence of the sodium salt of a weak acid, and the experi-
mental data then communicated showed that the magnitude of the
influence of the sodium salt is closely related to the strength of the
acid from which it is derived. The solubility of benzoic acid, for

SALTS ON THE SOLUBILITY OF SPARINGLY SOLUBLE ACIDS, 1467

instance, is greater in a sodium acetate solution than in a sodium
formate solution of the same concentration, and greater in this sodium
formate solution than in the corresponding sodium salicylate solu-
tion. The weaker the acid from which the sodium salt is derived,
the greater is the influence of this salt on the solubility of beni-oic or
any other sparingly soluble acid.

The experimental work on which this general conclusion was based
has been considerably extended, and the new results are communi-
cated in the present paper. They not only con6rm what has been
stated in the first paragraph, but supply also further illustration of
a peculiar relationship which was indicated in the course of the earlier
work. It was then found that, whilst benzoic acid is considerably
more soluble than salicylic acid in pure water, their positions are
reversed in sodium formate solutions of greater concentration than
0"04-^V. This is not an exceptional case, for several examples of the
same relationship have been discovered in the course of the more
recent work.

It appears, therefore, that if, of two sparingly soluble acids, the
weaker is also the more soluble, then under the influence of any sodium
salt the solubility of the stronger acid is increased to a greater extent
than that of the other. If the difference in solubility of the two acids
in water is not too great, then the curves obtained by plotting the
solubility against the concentration of the sodium salt will intersect at
a low value of the latter. That the occurrence of such an intersection
is in harmony with the law of mass action and the theory of
electrolytic dissociation was shown in the earlier paper, where a
formula was deduced connecting the increase in solubility of the acid
with the concentration of the added salt. Although only approxi-
mate, this formula served very well to show the general character of
the influence which a sodium salt, NaA', may be expected to exert on
the solubility of an acid, HA, and to show also the relation between
the solubility and the strength of the acids HA and HA'.

In the present paper the experimental values have been compared
with those calculated by Noyes' equation {Zeitsch. 2)^iysikal. Chem.,
1898, 27, 273), and it will be seen that so long as the concentration
of added salt is not very great, the agreement between the two sets of
values is quite good. Noyes has shown that if nio, m, and ao represent
respectively the solubility of a sparingly soluble acid in pure water, the
solubility in a salt solution of concentration n, and the degree of
dissociation in the saturated aqueous solution, and if as = w - mo{l — Oo),
then a;^ + rx- - (rn + ka)x - kaf = 0. The symbol ka represents the solu-
bility product for the acid in question, and r = ka/fcd, kd being the
dissociation constant of the acid from which the sodium salt is derived.
As Noyes has pointed out, this formula can be deduced only by making

5 D 2

1468 PHILIP AND GARNER: INFLUENCE OF VARIOUS SODIUM

. certain assumptions, but it may be regarded as fairly accurate so long
as the acid is sparingly soluble and n is small. It is clear then that,
subject to these limitations, the solubility of a sparingly soluble acid
in a sodium salt solution of concentration ?i can be predicted, pro-
vided one knows (1) the solubility in pure water, and (2) the disso-
ciation constants of the acid itself and of the acid from which the
sodium salt is derived.

Consideration of the foregoing formulae will show that if the ex-
perimental value of m is taken, and x is deduced by the relation
x = ')n - mo{l - «(,), then the equation x^ + rx"^ — {rn + ka)x — ka'r = 0 fur-
nishes a means of finding the value of ha- It is possible, in other
words, with the help of Noyes' equation to find the dissociation con-
stant (jf a weak acid by determining the influence of its sodium salt on
the solubility of any sparingly soluble acid, the dissociation con-
stant of which is known. A study of the experimental data from this
point of view shows, however, that the values so obtained for the
dissociation constant are subject to considerable variation ; they are
very sensitive to experimental error in the determination of the solu-
bility, and can therefore be taken as indicating only the approximate
magnitude of the dissociation constant.

Experimental.

The determinations of solubility were carried out at the tempera-
ture of 25°±0'1°, and the procedure adopted was that described in the
earlier paper. The pure acids employed were obtained in almost all
cases from Kahlbaum, and the values found for their solubility at 25°
are as follows : Benzoic acid, 0'0277 ; salicylic acid, 0*0164; 7n-nitro-
benzoic acid, 0'0205 ; o-chlorobenzoic acid, 00136; 3 : 5-dinitro-
benzoic acid, 0*0062 ; 2 : 4-dinitrophenol, 0*0027. These numbers are
the concentrations of the saturated aqueous solutions in gram-
molecules per litre.

The results of the experimental work are summarised in the
following tables, where the solubilities of the acids and the concentra-
tions of the sodium salts are given in hundredths of a gram-molecule
per litre.

SALTS ON THE SOLUBILITY OF SPARINGLY SOLUBLE ACIDS. 14G0

Table I,
Sodium Acetate Solutions,

Solubility of

Concen- ^ — — .^

tration 2 : 4-Di-

of sodium Benzoic Salicylic o-Chloro- ?;i-Nitro- 3 :5-Dinitro- nitro-

•acetate. acid. acid, benzoic acid, benzoic acid, benzoic acid. phonoU

)-00 •2-77 1-64 1-36 2-05 0-62 0-27

.•19 _ _ _ _ 1-60 0-97

.•23 3-76 2-61 2-30 303 — —

5-96 _ _ _ _ 317 1-62

(•06 5^13 4^29 3^95 4^75 — —

;91 _ _ _ _ 5-67 2^37

)-13 6-95 6-92 6-68 7^55 — —

.•85 — — — — 9-98 3-51

!^28 9-77 12^17 11-67 12-14 — —

Table II.
Sodium Formate Solutions.

Solubility of

Concentration
of

Benzoic

Salicylic

o-Chloro-

??i-Nitro-

sodium formate.

acid.

acid.

benzoic acid.

benzoic acid

0-00

2-77

1-64

1-36

2-0.'J

1^19

3-31

2-46

—

—

1-24

—

—

2-16

2-86

2-40

3-73

3-20

—

—

3^09

—

—

3-36

3-82

5-97

4-49

5-15

—

—

6-17

—

—

4-88

5-16

11-97

5-45

7-56

—

—

12-37

T

VBLE III.

7-04

7-12

Sodium Monochloroacetate Solutions.
Solubility of

Concentration
of .sodium

Benzoic

Salicylic

?ii-Nitrobeiizoic

monochloroacetate.

acid.

acid.

acid.

0-00

2-77

1-64

2-05

1-18

3-02

2-05

2-44

2-94

3-30

2-59

2-92

5-87

3-62

3-36

3-51

11-76

4-04

4-47

4-35

Concentration of
sodium .'succinate.

0-00

0-73

1-81

3^61

7-24

Table IV.
Sodium Succinate Solutions.

Solubility of

Benzoic acid.
2-77
3-35
4-19
5-38
7-38

Salicylic acid.
1^64
2^15
3-14
4-75
7-84

14.70 PHILIP AND GARNER: INFLUENCE OF VARIOUS SODIUM

Table V.

Pdtassium

Formate

Solutions.

Solubil

ity of

Concentration of

Benzoic

Salicylic

o-Chloro-

?«-Nitro-

potassium formate.

acid.

acid.

bcnzoic acid.

benzoic acid

0-00

277

1-64

1-36

2-05

1-22

3-35

2-45

217

2-84

3-05

3-88

3-57

3-34

3-86

6-10

4-51

5-16

4-82

5-12

Fia. 1.

Soluhility of salicylic acid in sohdions of sodium acetate, formate, and
monochloroacetate.

A,

/

y

^

^

2 4 6

MoL/lOO sodium salt per litre.

A study of the figures recorded in the tables will confirm what has
already been said, namely, that the weaker the acid from which the
sodium .salt is derived the greater is its influence on the solubility of
a sparingly soluble acid. In order to make this important point
thoroughly clear, the figures relating to the influence of sodium
acetate, sodium formate, and .sodium monochloroacetate on the solu-

SALTS ON THE SOLUBILITV OF SPAKINGLV SOLUBLE ACIDS. 14-71

bility of salicylic acid have been plotted in Fig. 1. A.s is well known,
monochloroacetic acid is stronger than formic acid, which in its turn
is stronger than acetic acid, and the relative i)osition of the curves in
the figure is in harmony with what has been said above. Similar
charts might be drawn for the acids other than salicylic acid.

An inspection of any of the tables will show that with a given
added salt, it is the stronger acids which exhibit the most rapid
increase in solubility. This important point is best elucidated by
reference to a particular case. The figures whicli represent the
influence of sodium formate on the solubilities of benzoic, ?M-nitio-
benzoic, and salicylic acids are recorded in table II, and the corre-

FiG. 2.
Solubility of benzoic, salicylic, and \n-nilrohcnzoic ari>h in sodium formate solutions.

•5 4

J

^.-"'^^

-^

^

—

Ben*2iS__-

^

y

4 6 8

Mol. /lOO sodium formate per litre.

10

12

sponding curves are traced in Fig. 2. It should be noted that the
strengths of these acids, as deduced from their dissociation constants,
are very different: benzoic acid, ^ = 0*00006; wi-nitrobenzoic acid,
^ = 0"000345 ; salicylic acid, ^ = 0'00102. The weakest acid is therefore
the most soluble of the three, and the strongest is the least soluble.
This statement is true for pure water, but is no longer valid when the
acids are dissolved in sodium formate solutions of greater concentra-
tion than O'OG-xV; under these conditions salicylic acid is the most
soluble, benzoic acid the least soluble, of the three acids.

Another very striking instance of this reversal of relative solubility
is furnished by the influence of sodium acetate on the solubilities of

1472 SOLUBILITY OF SPARI^^GLY SOLUBLE ACIDS.

benzoic acid (^' = 0'00006) and 3 : 5-dinitrobenzoic acid (A; = 0-0016).
The saturated solution of benzoic acid in water at 25° is 0"0277-^,
whilst that of 3 : 5-dinitrobenzoic acid in water at 25° is only 00062-iV.
In sodium acetate solutions, hovtever, of gx'eater concentration than
01-^V, dinitrobenzoic acid is more soluble than benzoic acid. Other
similar cases are to be found lu the material recorded in the tables.

Comparison of the figures in table V with those in table II brings
out the fact that potassium and sodium formates have almost exactly
the same influence on the solubilities of benzoic, salicylic, o-chloro-
benzoic, and ?«-nitrobenzoic acids. The curve obtained by plotting the
figures for the solubility of any one of these acids in potassium
formate solutions practically coincides with the corresponding curve
obtained from the figures for the solubility in sodium formate
solutions.

The experimental values recorded in the foregoing tables furnish
material, as already indicated, for testiog the applicability of the
formula deduced by Noyes (loc. cit.). The formula in question is
x^-Vrx'- -{rn + ka)x-kaT = 0, aiXiil, although not stringently exact, is
much more convenient to handle than the accurate, but very compli-
cated equation deduced by the same author. As Noyes himself has
pointed out in one or two cases, the values of the solubility
calculated by the simpler of the two formula) are near enough for
most purposes.

In order to make the comparison between theory and experiment,
the observed figures for the solubility were first plotted, and from the
curve so obtained the values of the solubility corresponding to certain
salt concentrations, namely, O'Ol, 002, 0'05, and 0'1-iV, were read off.
The calculated values of the solubility were obtained for each of these
concentrations by the formulae x^ + rx'^ - {rn + Jca)x - kaV = 0 and m =
x + mfi{l — ao). In table VI the calculated (A) and experimental {B)
values for each case are arranged side by side.

An inspection of the foregoing table shows that for solutions of
salicylic, benzoic, and o-chlorobenzoic acids dissolved in sodium acetate
and sodium formate solutions, the agreement between the calculated
and the observed values is good. It is less satisfactory where m-nitro-
benzoic acid and sodium chloroacetate solutions are involved. The
deviation between the two sets of figures, apart from some cases
where the difference is trifling, is such that the observed solubility is
greater than the calculated solubility. This is what was found by
Noyes and Chapin in the few cases in which they tested the
applicability of the formula.

In a few instances the values of the solubility have been calculated
by Noyes' more stringent and very complicated formula (Zeitsch,
physikcd. Clievi., 1898, 27, 273). The agreement between the calcu-

ORGANIC DERIVATIVES OF ARSENIC. PART II.

1473

Tablk VI.

Salt concentnition in inol./lOO per litre.

Salicj'lic acid in sodium acetate y/. 2

/>'. 2

Benzoic ,, ,, ,, y/. 3

i> II i» )> li. 6

o-Chlorobenzoic acid in sodium acetate A. 2

) ) )» >» M *^* ^

m-Nitrol)ciizoic ,, ,, ,, A. 2

>> >> »I 1> -O. .i

Salicylic acid in sodium formate ^L 2

>i >> )i ») !>. A

Benzoic ,, ,, ,, A, Z

B. 3

o-Chlorobenzoic acid in sodium formate A. 1

>> >) j> >> ■'->• ^

?n-Nitrobenzoic ,, ,, ,, A. 2

1 » ! I ) » 1 » h. it

Salicylic acid in sodium chloroacetato A. 2 00

i> )> )) j> ^- J- y /

Benzoic ,, ,, ,, A. 2*95

B. 2-96

wi-Nitrobenzoic acid in sodium chloroacetate. ^. 2 '34

.. B. 2-38

38

44
56
57
10
10
83
90

28
30
23
21
99
03
65
68

)> >>

2.

3-29
3-30
4-33
4-36
3 01
2-99
3-73
3-76

2-93
2-97
3-55
3-56
2-65
2-68
3-20
3-25

2-31
2-30
3-07
3-13
2-57
2-66

5.

5-99
5-95
6-20
6-34
5-71
5-68
6-24
6-50

4 57
4 67

3-00
316
3 32
3-54
3-06
3-36

10.

10 20

10-19

8-00

8-78

9-92

9-90

9 90

10-72

6-63
6-84
5-02

5 16

6 36
6-28
5-95
6 42

3-82
4-18
3-61
3-94
3 63
4-13

lated and the observed values is thereby somewhat improved on tbf
whole, but even then is by no means perfect.

Royal College of Science, London,
South Kensington, S.W.

CLXVI. — Organic Derivatives oj Arsenic. Part 11.
Triaminotriphe7iylarsine Oxide and Tricamijhoryl-
arsinic Acid.
By Gilbert T. Morgan and Frances M. G. Micklethwait.

In the production of ^j-aminophenylarsinic acid from aniline and
arsenic acid, a small proportion of bis-27-aminophenylarsinic acid
is also formed (Pyman and Reynolds, Trans., 1908, 93, 1180), but
the more highly substituted derivatives of arsenic pentoxide, which
are theoretically possible, have not been obtained in this con-
densation.

The authors have found that the prolonged interaction of
arsenious chloride and aniline in boiling benzene or toluene leads

1474. MORGAN AND MICKLETHWAIT :

to the formation of a condensation product containing three
aniline residues attached to arsenic, and differing from the additive
comjjounds of aniline and arsenious chloride prepared by Anschiitz
{AnnaJen, 1891, 261, 284), inasmuch as the latter are resolved
into their generators on treatment with water or alkalis.

Triaminotriphenylarsine Oxide, 0!As(CgH4*NH2)3.

A solution of 150 grams of arsenious chloride in 250 grams of
benzene is added to 750 grams of aniline diluted with 250 grams
of the same solvent. These materials must be thoroughly dried
beforehand. A crystalline precipitate of the additive compounds
is immediately formed, and gradually diminishes in bulk as the
mixture is boiled for fifty hours. After leaving the product for
three to eight weeks out of contact with moisture, the mixture is
rendered alkaline with sodium carbonate, and the excess of aniline
removed by distillation in steam. The hard resinous residue (about
22 — 25 grams) is dissolved in benzene, and the solution allowed to
evaporate, when several crops of a crystalline substance are
obtained, which, after repeated crystallisation from the same
solvent, melts at 189°.

The benzene mother liquors, when concentrated considerably,
yield an amorphous substance, which is also very soluble in cold
chloroform, being precipitated therefrom in a viscid form by means
of light petroleum. It was not found possible to crystallise this
product from any of the ordinary organic solvents, but, as it was
basic, purification was effected by repeatedly forming the soluble
hydrochloride and precipitating the base with ammonia. The sub-
stance was thus obtained as a grey, amorphous material, readily
soluble in alcohol, and precipitated therefrom by ether as a viscid
mass which hardens slowly in the desiccator ; it softens at 60°, and
decomposes indefinitely at 108° :

01826 gave 0-3952 CO2 and 0-0827 HoO. C-5901; H = 5-03.

0-2250 „ 0-4854 CO2 „ 0-1064 HgO. C = 58-83 ; H = 5-25.

0-1570 „ 15-7 c.c. No at 18-5° and 758 mm. N = ll-53.

0-1684 „ 17-0 c.c. N2 „ 18-5° „ 758 mm. N = ll-62.
As = (i) 20-57; (ii) 20-42 (see page 1481).
CjgHigONgAs requires C = 58-85; H = 4-90; N- 11-44;
As = 20*44 per cent.

The base is hygroscopic, and becomes soft and viscid on exposure
to the atmosphere.

Triaminotriphenylarsine oxide hydrochloride,

o:as(CcH4-nh2,hci)3,

is very soluble in water, and is precipitated as a grey, amorphous

ORGANIC DERIVATIVES OF ARSENIC. PART II. 1475

mass by passing hydrogen chloride into a benzene solution of the
base:

01140 gave 01010 AgCl. Cl = 21-92.

C]8Hi80N3As,3HCl requires CI = 22-35 per cent.

Tlie plafinichloriflc is an amorphous, yellow substance, sparingly
soluble in water, and insoluble in hydrochloric acid :

0-1274 gave 0-0388 Pt. Pt = 30-45.

2Cj8Hj80N3As,3HoPt.Clc requires Pt = 29-85 per cent.

TrihenzoylaminotriiihenyJarsine oxide, 0!As(CgH4'NH'COPh)3,
prepared by the Schotten-Baumann reaction, dissolves readily in
benzene, and is precipitated by petroleum as a light brown powder,
becoming viscid on exposure to air, and melting indefinitely at
130—140°:

0-2518 gave 14*0 c.c. No at 19° and 760 mm. N = 6-39.
C39H3QO4N3AS requires N = 6-18 per cent.

Triacetylaminotri'phenylarsine oxide, 0!As(C6H4*NHAc)3, pro-
duced by adding acetic anhydride to the base suspended in water,
dissolves in benzene, and is precipitated therefrom as a grey powder,
darkening at 120°, and decomposing indefinitely at 140 — 150°:

0-1196 gave 9-3 c.c. No at 20-5° and 768 mm. N = 8-97.
C24H24O4N3AS requires N = S-51 per cent.

Triaminotriphenylarsine oxide and the crystalline base melting
at 189° are also produced when the condensation is effected in
boiling toluene; the yield is about the same as in benzene, but the
products obtained in the less volatile solvent are darker in colour.

The hydrochloride of the crystalline base (m. p. 189°) is only
sparingly soluble in water, and in this way it can be separated
from triaminotriphenylarsine oxide hydrochloride. The crystalline
base separates from benzene in transparent, colourless spicules :

0-1723 gave 0-4256 CO2 and 0-0980 HoO. C = 67-37; H = 5-80.*

0-1748 „ 15-4 c.c. No at 27° and 770" mm. N = 9-85.
As = (i) 17-22; (ii) 17-20 (see page 1481).
C24H20N3AS requires C = 67-45; H = 5-15; N = 9-83;
As = 17-56 per cent.

These results indicate that the substance contains four phenyl
residues a.ssociated with one arsenic and three nitrogen atoms. The
formulae C6H5-NH-CcH4-As(CcH4-NH2)2 and

C6H5-NH-C6H4-As(NH-C6H,)-CcH4-NH2
correspond with these conditions, but it was not found possible to
elucidate completely the constitution of this base with the amount
of material obtainable. Benzoylation led to the production of a

♦ Duplicates: 0 = 67-90; C = 67'84; C = 67-84.
H= 5-68: H= 5-95; H= 5-98.

1476 ORGANIC DERIVATIVES OF ARSENIC. PART II.

dibenzoyl derivative, crystallising in colourless, refractive plates
melting at 221—222°.

Tricampho7'i/larsinic Acid, (CioHj50)3As(OH)o.

Sodium camphor and arsenious chloride were condensed in dry
toluene in the manner indicated in a previous communication
(Trans., 1908, 93, 2144), and the product extracted repeatedly
with aqueous sodium hydroxide. After precipitation with mineral
acid, the acidic products were extracted with small quantities of
benzene until a residue was obtained consisting of crude di-
camphorylarsinic acid {loc. cit.) ; the benzene extracts also yielded
small quantities of this substance. The final brown mother liquors
were evaporated to dryness, the residue dissolved in dilute aqueous
sodium hydroxide, and the solution boiled with animal charcoal and
concentrated to the crystallising point. The crystals, which consist
of sodium dicamphorylarsinate, were removed, the solution acidified,
and the viscid precipitate again subjected to the treatment with
benzene and sodium hydroxide to remove further quantities of
dicamphorylarsinic acid. The precipitate finally obtained was a
brown, uncrystallisable solid, softening at 110°, and melting
indefinitely at 130°. This acid dissolved in water containing a
small amount of alcohol; it was extremely soluble in benzene,
alcohol, or acetic acid, separating in a viscid condition from its
concentrated solutions in these solvents. A specimen obtained by
repeated treatment with benzene and sodium hydroxide, when dried
in the desiccator, gave the following results:

0-1580 gave 0-3716 COo and 0-1176 HoO. C = 64-12; H = 8-27.

0-3961 „ 0-0988 Mg^AsA- As = 12-07.

CgoH^yO^As requires C = 64-05; H = 8-36; As = 13-34 per cent.

Tricamphorylarsinic acid, when treated with aqueous sodium
hydroxide, became viscid and then dissolved, forming a very soluble
sodium salt. The silver salt was obtained as a greyish-white pre-
cipitate on adding silver nitrate to an aqueous solution of its
ammonium salt:

0-1332 gave 0-0380 Ag. Ag = 28-53.

C3oH450r^Ag2As requires Ag = 27-83 per cent.

When heated with excess of aqueous sodium hydroxide at
130 — 140°, sodium tricamphorylarsinate was hydrolysed into
camphor and sodium arsenate. The toluene solution, con-
taining the non-acidic condensation products from sodium
camphor and arsenious chloride, was distilled to remove the
solvent. The residue yielded a large amount of camphor and
small quantities of dicamphoryl, and a substance crystallising in

THE ESTIMATION OF ARSENIC IN ORGANIC COMPOUNDS. 1477

well-defined hexagonal and rectangular plates (m. p. 209 — 210°).
This product, which gave a benzoyl derivative melting at 170°,
had a composition approximating to that of tribornylarsine, but
the yield was so small that the compound was not further
examined.

The authors desire to express their thanks to the Government
Grant Committee of the Royal Society for a grant which has partly
defrayed the expenses of this investigation.

RoYAti College of Science, London,
South Kensington, S.W.

CLXVII. — The Estimation of Arsenic in Organic

Compounds.

By Harry F. V. Little, Edward Cahen, and Gilbert T. Morgan.

Recent developments in the investigation of organic derivatives of
arsenic have brought into prominence the problem of estimating
this element when directly combined with carbon. Of the various
methods hitherto adopted for destroying the organic matter in
these substances, the following may be mentioned :

(1) Combustion of the substance mixed with soda-lime by
heating in a stream of air or oxygen ; the residue is dissolved in
hydrochloric or nitric acid, the arsenic then precipitated as
sulphide, and finally converted into magnesium pyroarsenate (La
Coste and Michaelis, Aiinalen, 1880, 201, 224).

(2) Oxidation of the organic arsenic derivative by fusion with
sodium peroxide, the arsenic being estimated gravimetrically as
pyroarsenate (Pringsheim, Amer. Chem. J., 1904, 31, 386).

(3) Destruction of the organic matter with nitric acid containing
magnesium nitrate, when a final ignition leads to the formation of
magnesium arsenate (Monthule, Ann. Chim. anal., 1904, 9, 308).

Exception has been taken to the sodium peroxide method on the
ground that at the high temperature produced by the oxidation
some loss of volatile arsenic compounds may result. After a long
series of experiments, the authors arrive at the conclusion that
with due care in mixing and heating the reagents the loss becomes
almost inappreciable, even when the oxidation is violent and the
substance employed somewhat volatile.

The chief difl&culty arises at a later stage of the operation,

1478 LITTLE, CAHEN, AND MORGAN :

namely, in the precipitation of magnesium ammonium arsenate in
the presence of the large excess of alkali salt produced from the
sodium peroxide. Contrary to expectation, the results obtained
were almost uniformly too high, even when measured quantities
of " magnesia mixture " and the other reagents were employed.
Satisfactory values were obtained by redissolving the magnesium
ammonium arsenate and reprecipitating it with ammonia, but this
procedure renders the analysis very long and tedious, as the two
precipitations each require considerable time for their completion.

The aqueous extract of the fusion was next acidified with
hydrochloric acid and distilled with a ferrous salt in a current of
hydrogen chloride in accordance with Fischer's method as modified
by one of us (Trans., 1904, 85, 1001). Owing, however, to the
unavoidably large bulk of solution, the volatilisation of the
arsenious chloride was completed only after a lengthy distillation,
and accordingly this process was abandoned in favour of a
volumetric method, by means of which fairly accurate results could
be obtained in a comparatively short time.

In the method ultimately found to give satisfactory results, the
sodium peroxide fusion was retained, but the gravimetric estimation
was suj^erseded by a volumetric process due to Gooch and Browning
(Am^r. J. Sci, 1890, [iii], 11, 66).

The reaction involved may be sufficiently indicated by the
following equation :

A8205 + 4HI^ AS2O3 + 2H2O + 2I2,
these authors having shown that the change takes place quan-
titatively from left to right when the liberated iodine is removed by
boiling. The arsenious oxide is then titrated with standard iodine
in the usual way.

Procedure.

The finely powdered substance (0"2 to 0"3 gram) is mixed in a
nickel crucible with 10 to 15 grams of sodium peroxide and
sodium carbonate in equal proportions, a portion of these reagents
being spread over the mixture to prevent loss by projection. A
gentle heat is applied for about fifteen minutes, and the fusion
completed by raising the temperature to dull redness for five
minutes. With careful mixing and heating, the oxidation generally
takes place without fuming or detonation.

The contents of the crucible are extracted with water and rinsed
into a 450 c.c. conical flask. From 25 to 31 c.c. of sulphuric acid
(1:1) are added cautiously, and, if necessary, the solution is boiled
down to 100 c.c, when 1 gram of potassium iodide is introduced,
and the liquid further concentrated to 40 c.c. A few drops of

THE ESTIMATION OF ARSENIC IN ORGANIC COMPOUNDS. 1479

dilute sulphurous acid are added to destroy the last traces of iodine,

and the bright green solution is diluted considerably with hot
water and saturated with hydrogen sulphide. The arsenious
sulphide is collected, washed about three times with hot water,
dissolved off the filter with 20 c.c. of i\72-sodium hydroxide, and
the filtrate returned to the conical flask, where it is treated with
30 c.c. of hydrogen peroxide (20 vols.), the excess of this reagent
being destroyed by heating on the water-bath for ten minutes.
After the frothing has subsided, a few drops of phenolphthalein
are added, followed by 11 c.c. of sulphuric acid (1 : 1), this quantity
giving 10 c.c. in excess. One gram of potassium iodide is now
added to the liquid, which should have a volume of 100 c.c, and
the solution concentrated to 40 c.c, when its pale yellow colour is
removed by a few drops of dilute sulphurous acid. Cold water
is quickly added, and the diluted solution neutralised with
2T-sodium hydroxide and just acidified with sulphuric acid. The
requisite amount of 11 per cent, sodium phosphate (see Note 3)
is added, and the arsenite solution titrated with standard iodine and
starch in the usual way.

Notes on the Method.

1. A gravimetric estimation may be effected by proceeding as
far as the oxidation of the sulphide with alkaline hydrogen
peroxide and then precipitating as magnesium ammonium arsenate
by Austin's method (Zeitsch. anorr/. Chem-., 1900, 23, 146).

2. The manipulation might be simplified by estimating directly,
by Gooch and Browning's method, the arsenate in the filtered
aqueous extract of the fusion. The filtration of nickel hydroxide
and carbonate is, however, extremely tedious, and this modification
of the process does not lead to greater rapidity or accuracy. The
precipitate may be rendered more amenable by oxidation to
nickelic hydroxide with the aid of bromine, but the results obtained
in the titration are not satisfactory.

3. The titration may be carried out in the presence of sodium
hydrogen carbonate, but the addition of disodium hydrogen
phosphate, which has been advocated by E. Washburn, is preferable
{J. Ainer. Chem. Soc, 1908, 30, 31). The volume of 11 per cent,
sodium phosphate added should be equal to the number of c.c. of
iY/10-iodine required in the titration.

4. The arsenic derivatives employed in working out the method were
atoxyl and hexamethyltriaminotriphenylarsine, As[C(;H^'N(CH3)o].o,
m. p. 239—240° (Michaelis and Rabinerson, Annalen, 1892, 270,
140) ; the latter compound has the advantage over atoxyl and many
of its allies in not containing water of crystallisation. The purity

1480

LITTLE, CAHEN, AND MORGAN

of the base was shown by its combustion: C = 6622, 11 = 684,
theory requiring C = 66'21 and II = 6"89 per cent.*

A typical selection of the analytical results are shown below in
tabular form.

Tables of Results.

Strength of Iodine Solutions.

A = 0-0969-i\^ B = 0-10040-.V.

C = 0-1010-i\'. D = 0-04032-i\^

I. Aioxyl (Martindale, First S.imple).

H20 = 193 per cent. As = 25'31 per cent, (calculated).

Arsenic

Substance.
0-1288
0 1 735
0-2763
02476*
0-3030*

C.c. iodine used.
9-03 Sol. A
1205 „
19-09 „
17-17 „
20-92 „

Taken.
0-0326
0 0439
0-0699
0 0627
0 0767

Fonnd.
0 0328
0-0438
0 0693
0-0624
0-0760

per cent
25-46
25-22
25-08
25-19
25-07

II. Atoxyl (Martindale, Second Sample).

H20 = 25-87 per cent. As = 23"28 per cent, (calculated).

Arsenic

Substance.

C.c. iodine used.

Taken.

Found.

]per cent

0-2722

17-50 Sol. A

0 0634

0-0635

23-34

0-2464

16-10 ,,

0-0574

0-0585

23-73

0 2288

14-86 ,,

0-0533

0-0540

23-58

0-2518

16-27 ,,

0-0586

0-0591

23-46

0-2482

16-16 ,,

0-0578

0-0587

23-63

0-2006*

12-37 Sol. B

0-0467

0-0466

23 -21

0-1964*

12-27 „

0 0457

0-0462

23-52

II. Atoxyl (Poulenc).

H20 =

1891 per cent. As

= 25-44 per

cent, (calculated).

C.c. iodine used.

Arsenic

Substance.

Taken.

Found.

per cent

0

3260

22-88 Sol. A

0-0829

0 0831

25-49

0

2608

18-25 „

0-0663

0 0663

25-42

0

2478*

17-35 „

0 0630

0-06.30

25-42

0

2814*

19-60 „

0-0716

0-0712

25-30

0

2528*

17-90 ,,

0-0643

0-0650

25-71

0

2486*

17-43 ,,

0-0632

0-0633

25-46

0

2550

17 04 Sol. B

0-0649

0-0641

25-16

0

2022

13-76 „

00514

00518

25-62

0

2368

16 03 ,,

0-0602

0-0603

25-48

Those estimations denoted by an asterisk were carried out on
the aqueous extract of the fusion (compare Note 2, p. 1479).

As the amount of water in different samples of atoxyl varies con-

* The authors' thanks are Ana to Mr. A. Tarzey for hi.s assistance in carrying out
many of the preliminary experiments and analyses.

THE ESTIMATION OF ARSENIC IN ORGANIC COMPOUNDS. 1481

siderably, it was estimated for each specimen, .and tlic theoretical
percentage of arsenic calculated from this result.

IV. Ilexaviethyltriaminotrijihenylarsine. As=17"23 percent.

ArsiMiin

Substance.

C.c. iodine usod.

Taken.

Fouiul.

licT C(;nt

0-29:54

13-23 Sol.

B

0 -05.05

0-04.08

1G-9S

0-2070

9-29 ,,

0-0357

0-0350

16-89

0-2482

11-39 „

0 0428

0-04 29

17-26

0-2176

994 „

0-0375

0-0374

17-20

0-3198

14-33 „

0-0551

0-0540

16-87

0-2628

11-65 ,,

0-0453

0-0139

16 -69

0-1814

8-22 Sol.

C

0-0312

00311

17-16

V. Dicaniphori/larsinic Acid
(Marti udale).

As= 18-3 per cent.

Substance. Iodine, Sol. C. Found.

0-2426 11-42 c.c. 17-82

0-2148 10-15 „ 17-90

0-2(570 12-51 „ 17-74

VI. -^-Toh/larsinic Acid
(Martindale).

As = 34-7 per cent.

Sn1)stance. Iodine, Sol. C. Found.

0-1449 12-88 c.c. 33-67

0-2042 18-24 „ 33-83

0-1104 lost 0'0090 HoO at 125°

VI r. Sodium Tetraiodocacodylate
(Martindale).

As = 10 per cent, for

(CHggAsO-ONa.SJHgO.

Substance. Iodine, Sol. C. Found.

0-6912 18-78 c.c. 10-28

0-6518 17-70 „ 10-28

0-6864 18-70 „ 10-31

VIII. Triamin olripheni/larsine
Oxide (Morgan and Mickle-
thwait, p. 1474).

As = 20-44 per cent.

Substance. Iodine, Sol. C. Found.

0-2474 13-44 c.c, 20-57

0-3372 18-18 ,, 20-42

IX. rhenyJlriaminotripliPMylarsine

(Morgan and Micklethwait,

p. 1475).

As = 17-56 per cent.

Substance. Iodine, Sol. Z>. Found.
0-1552 17-68 c.c, 17-22

0-2219 25-25 ,, 17-20

X, Toluene -p- sulphonyl- p-andno-
phenylarsinic Acid.

As = 20-22; S = 8-63 percent.

C-Il7-SO,-NH-C,H4-A.sO(OII)2.

Substance. Iodine, Sol. D. Found.
0-1618 21-40 c.c. 19-99

0-23-20 30-25 „ 19-73

0-1968 0-1-236 BaSOj S = 8-62

XI. Bis-'2-aminotolyl-5-arsinic Acid
(Burroughs, Wellcome & Co.).

As = 23-44 per cent.

(NH2-C7Hg)oAsO(OH).

Substance. Iodine, Sol. C. Found.
0-2280 13-70 c.c. 22-76

0-3228 19-41 „ 22-77

VOL. XCV.

XII. Bis-p-acetylaminophenyl-

arsinic Acid
(Burroughs, Wellcome & Co.).

As = 19-95 per cent.

(CH3-CO-NH-CcHj2AsO(OH).

Substance. Iodine, Sol. 6'. Found.

0-2248 11-54 c.c. 19-44

0-3558 18-40 ,, 19-59

5 E

14S2 EWINS : THE ACTION OF PlIORPIIORUS PENTACIILORIDE

XI 11. Monosodium i-hydroa'y-
"1' -benzenejtzololu^iie-b -ars'mate
(Burroughs, Wellcome it Co.).

As = 20-95 per cent.

OH-C6H4-N:N-C7Hg-AsO(OHXONa).

Substauce. Iodine, Sol. C. Found.
0-1978 10-80 c.c. 20-67

0-2242 12-10 ,, 20-44

XIV. Sodium l-hydroxytolyl-

Kt-arsinaie
(Burroughs, Wellcome k, Co.).

As = 29-53 per cent.

OH-C7Hg-AsO(OH)(ON"a).

Substance. Iodine, Sol. B. Found.
0-2083 40-65 c.c. 29-49

0-1405 27-00 ,, 29-05

^Kotes on the forcyoiny Estimations.

1. A substance containing little or no oxygen requires a pro-
portionately larger amount of sodium peroxide. With hexamethyl-
triaminotrijjhenylarsine, for example, it was found difficult to avoid
a violent oxidation. This circumstance accounts for the somewhat
low results usually obtained in the analysis of this base.

2. Compounds containing iodine, such as sodium tetra-
iodocacodylate, give rise on fusion to sodium iodate, which necessi-
tates the addition to the acidified extract of sufficient sulphurous
acid to reduce this salt to iodide, the reduction of the arsenate
being then effected in the usual way.

3. Toluene-'p-sitljjhonyl-T^-amino'phenylarsinic acid (X), which
contains both arsenic and sulphvir, was prepared from atoxyl by
the Schotten-Baumann reaction ; it dissolves very sparingly in
•water, although its alkali salts are extremely soluble in this solvent.

The authors desire to express their thanks to Dr. W. H. Martin-
dale and to Dr. F. L. Pyman for their kindness in supplying
specimens for analysis.

Royal College of Science, London,
South Kensington, S.W.

CLXVIIL — The Action of Pliospliorus Pentachloride
on the Methylene Ethers of Catechol Derivatives.
Part V. Derivatives of Protocatechuyl Alcohol
and Protocatechuonitrile.

By Arthur James Ewins.

In Part I of this series (Barger, Trans., 1908, 93, 567) it was
stated that " phosphorus pentachloride acting on piperonyl alcohol
produced a tar from which nothing could be isolated." In the

ON THE METHYLENE ETHERS OF CATECHOL DERIVATIVES. 14S3

course of subsequent experiments the author found, however,
that if 3 : 4-methylenedioxybenzyl chloride, CHotOo'.CgHs-CH.Cl
(" piperonyl chloride," corresponding with the alcohol), be used
instead of the alcohol itself, the reaction with phosphorus penta-
chloride proceeds in the normal manner. 3 : 4-Methylenedioxy-
benzyl chloride has been previously obtained by Decker and Koch
(Ber., 1905, 38, 1739) by passing hydrogen chloride into a cold
benzene solution of piperonyl alcohol. In the present investiga-
tion it was found that this substance, on treatment with two
molecular proportions of phosphorus pentachloride at 110°,
is transformed to 3 : 4-dichloromethylenedioxybenzyl chloride,
CCl2i02iC(;H3*CH2Cl, which by subsequent treatment with formic
acid yields 3 : 4-carbonyldioxybenzyl chloride, CO!02lCgH3-CH.2Cl.
This cyclic carbonate has been obtained quite recently by Pavily
and Alexander {Ber., 1909, 42, 2350) by the partial reduction of
3 : 4-carbonyldioxybenzylidene chloride ('' dichloropiperonal ").

The hydrolysis of 3 : 4-carbonyldioxybenzyl chloride to proto-
catechuyl alcohol, CcH3(OH)2"CHo*OH, was attem^Dted. In one
experiment an impure crystalline compound was obtained which
had all the properties that this alcohol might be expected to
possess. The substance was very readily soluble in water, alcohol,
etc., but quite insoluble in benzene or xylene; its aqueous and alco-
holic solutions gave an intense green coloration with ferric chloride,
and the substance was easily oxidised. It was, however, found
impossible to obtain the compound in a state of sufficient purity
for analysis. For the preparation of 3 : 4-methylenedioxybenzyl
chloride, the method due to Decker and Koch was employed, with
a slight modification. Hydrogen chloride was passed into the dry
ethereal solution of piperonyl alcohol, and the residue distilled
after removal of the ether. As thus obtained, 3 : 4-methylene-
dioxybenzyl chloride was a liquid which could not readily be
crystallised. In some experiments carried out in this manner
there was produced on distillation a non-volatile solid, which was
found to be practically insoluble in most organic solvents, and
appears to be a dihydroanthracene derivative. The formation of
this compound is probably due to the condensation of two molecules
of 3 : 4-methylenedioxybenzyl chloride with elimination of hydrogen
chloride, according to the equation ;

2CH2:o2:c6H3-cH2Ci = CH2:o2:c6H2<^22>cv,H,;o2:cH2 + 2 u c

It was further found that this condensation could be brought
about either by the action of phosphorus pentachloride directly
on piperonyl alcohol under certain conditions, or by the action of
phosphoryl chloride on 3 : 4-methylenedioxybenzyl chloride. The

5 E 2

1484 EWINS: THE ACTION OF PHOSPHORUS PENTACHLORIDE

impossibility of obtaining 3 : 4-carbonyldioxybenzyl chloride by the
direct action of phosphorus pentachloride on piperonyl alcohol is
thus explained, since the phosphoryl chloride and 3 : 4-methylene-
dioxybenzyl chloride first produced would react further and bring
about the above condensation. By controlling the reaction so as
to minimise charring, a certain amount of the hydroanthracene
derivative was actually obtained directly from piperonyl alcohol by
the action of phosphorus pentachloride.

After the reduction of 3 :4-methylenedioxymandelamide,
CHo:Oo:CfiH3-CH(OH)-CO-NHo (Barger and Ewins, Trans., 1909,
95, 555), to an alkamine had proved unsuccessful, the action of
phosphorus pentachloride on this compound was investigated. It
was hoped that by this means a compound of the constitution
COIOglCgHg'CHCl'CN (3 : 4-carbonyldioxyphenylchloroacetonitrile)
would be obtained. By the action of four molecular proportions
of phosphorus pentachloride at 130°, a mixture of compounds was
produced, the main product being 3 : 4-methylenedioxyphenyl-
dichloroacetonitrile, CHot02'CfjH3*CCl2'CN, which on boiling with
formic acid was converted into 3 : 4-methylenedioxyphenylglyoxylo-
nitrile, CHoIOo'CfiHg'CO'CN. This compound on boiling with
water readily yielded piperonylic acid. The methylene grouping
in the amide was thus seen to be for the most part unattacked under
the conditions employed. With more than four molecular propor-
tions of phosphorus pentachloride, a mixtvire of substances was pro-
duced from Avhich nothing could be distilled. In a recent paper
by Titherley and Worrall (Trans., 1909, 95, 1143), it has been
shown that phosphorus pentachloride acting on primary amides
produces a mixture of compounds containing pho.sphorus, and the
failure to obtain the desired compound from 3 : 4-methylene-
dioxymandelamide may be attributed to this fact.

The fact that 3 : 4-methylenedioxyphenylglyoxylonitrile was pro-
duced in the manner described above gave reason for the belief
that by acting on piperonylonitrile, CHolOo^CgHg'CN, with phos-
phorus pentachloride at a high temperature, the hitherto vm-
described nitrile of protocatechuic acid might be obtained. This
was indeed found to be the case. Piperonylonitrile, when acted
on by two molecular proportions of phosphorus pentachloride in
boiling toluene, gave, in the first place, 3 : 4-dichloromethylene-
dioxybenzonitrile, CCU'OgiCfjHg'CN. This substance reacted in the
cold with formic acid, giving 3 :4-carbonyldioxybenzonitrile,
COIOo'QH^'CN, which on boiling with water was converted into
protocatechuonitrile, C(jH3(OH)2'CN.

ON THE METHYLENE ETHERS OF CATECHOL DERIVATIVES. 1485

Experimental.
3 -A-Dichloromethylenedioxyh enzyl Chloride, CCl2i02*C6H3*CH2Cl.

3 : 4-Metliylenedioxybenzyl chloride (20 grams), purified by dis-
tillation under diminished pressure (b. p. 134 — 135°/ 14 mm.), was
heated with two jnolecular proportions (49 grams) of phosphorus
pentachloride to 110° for four hours. On distillation, 20 grams of
a liquid (b. p. 154 — 156°/ 16 mm.) were obtained:

0-1098 gave 0-1932 AgCl. Cl = 43-5.

C8H5O2CI3 requires CI = 44-4 per cent.

As is usual in the very unstable derivatives of this type, the
chlorine content is rather low.

Z-A-Carhonyldiooi/h enzyl CJiloride, COIO.XVJIy'CHaCl.

The distillate obtained as described above reacted vigorously
with formic acid in the cold, and if the solution were kept
moderately concentrated a crystalline solid separated almost at
once. The substance was recrystallised from light petroleum (b. p.
80 — -90°), from which it separated in long needles, melting at 57°.
Yield, 80 per cent, of the theoretical :

01524 gave 01186 AgCl. Cl = 19-1.

CgH^OgCl requires 01 = 19-2 per cent.

For this substance, prepared by the careful partial reduction of
3 : 4-carbonyldioxybenzylidene chloride, Pauly and Alexander {loc.
cif.) give m. p. 53-5 — 54°.

With the view of obtaining protocatechuyl alcohol,
C«H3(OH)2-CH2'OH,
hydrolysis was carried out in the following manner.

3 : 4-Carbonyldioxybenzyl chloride, obtained as above, was dis-
solved in ten times its weight of acetone, and water added in suffi-
cient quantity to produce a slight turbidity. Acetone was then added
drop by drop until a clear solution was again produced. Slightly
less than the theoretical proportion of powdered marble w-as
added, and the mixture boiled under a reflux condenser until all
the marble had become converted into calcium chloride by the
hydrochloric acid produced in the reaction. The disappearance of
the marble served to indicate the complete replacement of the
chlorine by hydroxyl. The acetone was then removed by distilla-
tion, the aqueous residue concentrated under diminished pressure
on a boiling-water bath, and the residue extracted with ether.
The residue, after removal of the ether, usually consisted of a
reddish-brown syrup. In one case the syrup spontaneously
crystallised, but the crystals, which were coloured, could not bef

1486 EWINS : THE ACTION OF PHOSPHORUS PENTACHLORIDE

freed from the mother liquor, nor could they be recrystallised, as
already stated, for want of a suitable solvent; no analysis was
therefore attempted. The residue left, on evaporation of the ether,
was in all cases free from halogen, very soluble in water, ether,
alcohol, acetone, and similar solvents, but quite insoluble in boiling
benzene, toluene, xylene, or light petroleum. Its aqueous solution
gave with ferric chloride a green coloration, which rapidly
became brown. In alcoholic solution the green coloration was
more permanent. Benzoylation, both according to Schotten-
Baumann and by Einhoi'n's method, gave a solid product, which
was evidently a mixture of benzoyl derivatives ; nothing crystalline
could be obtained from it. Acetylation gave similar results.

2: 3: 6: 7-(or 1: 2: 5: ^-)Dimethylenetetraoxydihydroanthracene,

As already stated, this compound may be produced in a variety
of ways. Its most convenient method of preparation was found
to be the following.

Pij^eronyl alcohol is dissolved in chloroform, and one molecular
proportion of phosphorus pentachloride added to the solution.
After the brisk reaction which ensues has subsided, the chloroform
is removed by distillation from a boiling-water bath, and the
residue heated at 100° for some time longer. A grey solid
separates, which is collected and washed with a little chloroform.
The solid is recrystallised from boiling nitrobenzene, in which it is
sparingly soluble, and from which it separates in fine whit€ needles,
which do not melt at 360°; when heated under a pressure of
20 mm., they sublime without much decomposition. The crystals
are very slightly soluble in glacial acetic acid, but almost insoluble
in all other organic solvents :

01335 gave 0-3511 CO2 and 0-0536 H.,0. C = 71-7; H = 4-5.

0-1353 „ 0-3523 CO. „ 0-0530 HgO. C = 71-0 ; H = 4-5.
CjgHj^O^ requires C = 71-6 ; H = 4-5 per cent.

The general properties of this substance (its sparing solubility,
its volatility, and its stability), in conjunction with its formation
from methylenedioxybenzyl chloride, indicate with considerable
probability that it is related to anthracene; its composition, indeed,
corresponds with that of a dimethylene ether of a tetrahydroxydi-
hydroanthracene, which would be formed from two molecules of
piperonyl chloride with loss of hydrogen chloride. It is, however,
difficult to remove all doubt as to its constitution. A molecular
weight determination was impossible, on account of its very slight
solubility in organic solvents, and, partly for the same reason,

ON THE METHYLENE ETHEKS OF CATECHOL DEKIVATIVES. 1487

attempts to oxidise it with chromic oxide to the corresponding
anthraquinone were unsuccessful. What appeared to.be a well
defined nitre- derivative was obtained as follows.

One gram of the substance was suspended in 8 c.c. of glacial
acetic acid, and an equal volume of nitric acid (D 1'4) was added.
The mixture became dark brown, oxides of nitrogen were evolved,
and crystals separated out. On recrystallisation from glacial acetic
acid, well-defined yellow prisms (m. p. 217°) were obtained. The
substance had no acidic properties; the yield was 0'24 gram:

01 453 gave 0-2767 CO2 and 00386 H2O. C = 51-9 ; H = 2-9.

0-2197 „ 15-6 c.c. No (moist) at 20° and 760 mm. ; N = 8-2.

From these figures it is impossible to deduce a satisfactory
formula; a c?i///^/-o-derivative of the original substance, of the
formula CieHio04(N0.2)2, would require C = 53-6; H = 2-8; N = 7-8
per cent.

3 : i-MethyleyiedioxyjjhenyhjIyojylonitrUe, CHolOo'.CcHg-CO-CN.

3 : 4-Methylenedioxymandelainide (5 grams) was heated with four
molecular proportions of phosphorus pentachloride (22 grams) to
150 — 160° for four hours. On distillation, 2-5 grams of a distillate
which boiled at 150°/8 mm. were obtained. With formic acid in
the cold, only a very feeble reaction was observed, but on boiling a
considerable evolution of hydrogen chloride was noticeable, and
the solution, on cooling, deposited a crystalline solid. This was re-
crystallised from light petroleum (b. p. 80 — 90°), and then melted
at 96—97° :

0-1245 gave 0-2783 CO. and 0-0325 HoO. 0-610; H = 2-9.
CgHAN' requires C = 61-7; H = 2-85 per cent.
This compound on boiling with water yielded piperonylic acid.

3 : A-DicJdoromethylenedioxyhenzonitrile, CCl2'OoIC6H3*CN.

179 Grams of piperonylonitrile, CHn'Oo'CcHj-CN, prepared by
heating piperonaloxime with acetic anhydride (Marcus, Ber., 1891,
24, 3657), were dissolved in 50 c.c. of toluene, and two molecular
proportions (50-8 grams) of phosphorus pentachloride added to
the solution. (The use of a solvent appears to be essential.) The
mixture was then boiled on a sand-bath under a reflux condenser for
five hours. On distillation, 20 grams of a liquid (b. p. 155 — •
156°/ 15 mm.) were obtained. This liquid, on keeping for a short
time, was transformed to a solid, crystalline mass, which melted
at 76 — 77°. The crystals are very unstable, readily evolving
hydrogen chloride on exposure to moist air. To this fact may be

1488 EWINS: CATECHOL DERIVATIVES.

attributed the somewhat low value obtained for chlorine on
analysis :

0-1712 gave 0-2040 AgCl. Cl = 29-5.

C8H3O0NCI0 requires CI = 32-8 per cent.

This compound is interesting as being a crystalline dichloro-
methylcne derivative, only one other crystalline compound of
this type (a/3-dichloro-a-3 : 4-dichloromcthylenedioxyplicnylethane,
Barger, Trans., 1908, 93, 2084) having hitherto been obtained.

3: ^-Carhonyhlioxyhenzonitrile, COI02*C6H3"CN.

3 : 4-Dicliloromethylencdioxybenzoniti'ile reacts readily in the
cold with formic acid, evolving hydrogen chloride. After a short
time a crystalline solid separates, which, when recrystallised from
benzene, forms broad prisms melting at 112°. Yield, 70 per cent,
of the theoretical :

0-2009 gave 14-8 c.c. No (moist) at 16° and 754 mm. N = 8-9.
CgHgOyN requires N = 8-7 per cent.

3 •A-Dihydroxyhenzonitrile (Frotocatechuonitrile), CgH3(OH)2*CN'.

3 : 4-Carbonyldioxybenzonitrile was suspended in water and the
mixture boiled. A brisk evolution of carbon dioxide took place,
and a clear solution was finally prodviced. On cooling, the solution
deposited crystals of protocatechuonitrile in long, white, fine needles,
w^hich, when dried in the steam-oven, melted sharply at 152°. Its
aqueous sokition gives the characteristic catechol colovir reactions
with ferric chloride :

0-2228 gave 20-1 c.c. N, (moist) at 18° and 759 mm. N = 10-4.
C7H5O2N requires Ni=10-4 per cent.

Protocatechuonitrile yields, on benzoylation by Einhorn's method,
a dihenzoyl derivative, which crystallises from absolute alcohol in
very long, fine threads, and melts at 131°.

The author wishes to express his thanks to Dr. G. Barger for his
ready help and advice throughout the work.

The Wellcome Physiological Reseakch Laboratories,
IIerne Hill, London, S.E.

THE PREPARATION OF DISULPHIDES. PART VI. 1480

CLXIX. — The Preparation of Disulphides. Part VL
Note on a New Method of Preparing Disidphides.

By Thomas Slateij Price and Douglas Frank Twiss.

It is soincvvliat surprising tliat. althougli the sodium and other
salts of the alkyl tliiosulphates liave been known for a considerable
time (Bunte, Jin:, 1874, 7, 64G; Purgotti, Gazzettn, 1890, 20, 25;
etc.), it is oidy comparatively recently that the reactions which
they undergo have been studied to any extent. Bunte and
Purgotti investigated mainly the hydrolytic action of acids with
the formation of mercaptans, and Purgotti noted the complex
decomposition which these compounds undergo when subjected to
the action of heat.

Since 1907 the authors have been engaged in further investiga-
tions on these compounds, and have shown how the corresponding
disulphides may be obtained from them (Trans., 1907, 91, 2021;
1908, 93, 1395, 1401, 1645; 1909, 95, 1050). Gutmann has also
studied the action of alkalis (Bcr., 1908, 41, 1650), and more
recently the action of acids {Be?:, 1909, 42, 228).

Whilst engaged in the investigation of diselenides (Proc, 1908,
24, 134), one of us, in conjunction with Mr. L. M. Jones, B.Sc,
found that these compounds are very readily prodvxced from the
alkyl selenosulphates by the action of iodine. The reaction takes
place very quickly at the ordinary temperature, and proceeds
according to the equation :

2KO-S02-SeR + 2H20 + Io = R.3Seo+2KHS04 + 2HI.

It has been supposed hitherto that the alkyl thiosvilphates do not
react with iodine; indeed, the method vised by Slator (Trans., 1904,
85, 1286; 1905, 87, 481) and by Slator and Twiss (Trans., 1908,
93, 1648) for determining the velocity of reaction between sodium
thiosulphate and organic halogen compounds depends on the fact
that the alkyl tliiosulphates are not affected by iodine at the
ordinary temperature. We have found, however, that at higher
temperatures reaction readily takes place with the formation of
the corresponding disulphides. In all probability, the reaction is
direct, and does not consist in a primary hydrolysis of the alkyl
thiosulphate by water and oxidation of the resulting mercaptan
by iodine. It is hoped that velocity measurements will throw light
on the mechanism of the reaction.

As will be seen from the experimental results, the yields of
disulphide are practically quantitative. The method is much more
satisfactory than the one employed by Blanksma (Rec. trav. chim.,
1901, 20, 137), which depends on the interaction between sodium

1490 THE PREPARATION OF BISULPHIDES. PART VI.

disulphide and the organic halogen compound. In the case of
nitro-derivatives, Blanksma has recently shown {Eec. trav. chim.,
1909, 28, 105) that the nitro-group also undergoes reduction to
some extent when sodium disulphide is used.

Experiments were also made in which iodine was replaced by
chlorine, but the results were not very satisfactory, the disulphide
obtained being contaminated to a considerable extent with the
mercaptan ; moreover, the yield was always poor.

The investigations detailed in our first paper (Trans., 1907, 91,
2021) have shown that the alkyl thiosulphatcs do not undergo
electrolytic oxidation, with the formation of disulphides, at a
platinum anode. We thought it possible, however, that if the
solution also contained a chloride, the chlorine liberated on passage
of the current would bring about the formation of disulphide.
Experiments made with sodium benzyl thiosulphate and sodium
2?-nitrobenzyl thiosulphate did not, however, give very satisfactory
results either in hot or cold solutions. In all cases, a small amount
of a dark pasty mass was formed on the rotating platinum anode,
and this was proved to contain disulphide, but at the same time,
especially when an acid anolyte was used, a considerable amount of
mercaptan was formed. Experiments in this direction were there-
fore discontinued.

Experimental.

Dihenzyl Disulphide. — A mixture of 5 grams of benzyl chloride,
10 grams of sodium thiosulphate, 30 c.c. of water, and 30 c.c. of
alcohol (95 per cent.) was heated on the water-bath under a reflux
condenser for one hour. Iodine was then added, in small portions
at a time, until the colour remained, the time required for this
operation being less than half an hour. The contents of the flask
were then cooled to the ordinary temperature, diluted with water
to precipitate any disulphide remaining in solution, and the excess
of iodine removed by careful addition of sulphurous acid. The
product so obtained was collected and dried; application of the
usual tests showed it to be dibenzyl disulphide. The yield of crude
product was 99 per cent., whereas the best yield obtained by the
electrolytic method was 86 per cent.

Dio-nitroh enzyl DimlpJiide. — This compound was prepared from
o-nitrobenzyl chloride in a similar way to that already described
for dibenzyl disulphide. The quantities taken were 10 grams of
o-nitrobenzyl chloride, 15 grams of sodium thiosulphate, 40 c.c. of
water, and 40 c.c. of alcohol. The reaction mixture was heated on
the water-bath for one hour, and the addition of the iodine extended
over half an hour.

MARLE: THE ESTIMATION OF CARBONATES. 1491

The yield of crude di-o-nitrobenzyl disulpliide obtained was 985
per cent., that is, practically quantitative. It is much better than
that obtained by the action of sodium carbonat'e, which was only
about 25 per cent. (Trans., 1908, 93, 1401).

Experiments were not made with the meta- and para-compounds,
since it was only the ortho-compound which gave very poor yields
by the sodium carbonate method.

Dimethyl Dlthiod'KjhjcoUate. — A mixture of 15 grams of methyl
bromoacetate, 25 grams of sodium thiosulphate, 50 c.c. of water,
and 50 c.c. of alcohol was heated on the water-bath for three-
quarters of an hour; 50 c.c. more alcohol and 12 grams of iodine,
in small portions at a time, were then added, the reaction taking
place rapidly. When the reaction was complete, the mixture was
cooled to the ordinary temperature, any excess of iodine removed
by the addition of sulphurovis acid, and then diluted with water to
precipitate the dimethyl dithiodiglycollate formed. The ester was
extracted with ether and recovered from the ethereal solution in
the usual manner. It was proved to be dimethyl dithiodiglycollate
by hydrolysis with aqueous hydrochloric acid and identification of
the dithiodiglycollic acid formed.

The yield of crude ester was 73 per cent., whereas the electrolytic
method gave only 60 per cent. (Trans., 1908, 93, 1645). Moreover,
there was no objectionable odour during the preparation, as was
the case when the electrolytic method was used.

We desire to express our thanks to the Research Fund Com-
mittee of the Chemical Society for a grant which partly covered
the cost of the foregoing investigations.

Chemical Depaktment,

Municipal Technical School,

BlUMINGHAM.

CLXX. — The Estimation of Carbonates in Presence of
Nitrites, Sulphides, or Sulphites by means of Potass-
ium Dichromate.

By Ernest Robert Marle.

Th.\t carbonates are decomposed by a strong solution of potassium
dichromate is probably well known, although the fact is seldom
noted in the text-books, and I have found little mention of the

1492 MARLE: THE ESTIMATION OF CARBONATES IN

subject in chemical literature. Chapman Jones (Qualitative
Chemical Analysis, 1906, 110) recommends the substitution of
dichromate for dilute acid in the detection of carbonates in presence
of nitrites, sulphides, or sulphites, none of which effervesce with
dichromate. Moissan (Trait e de Chhuie Minerale, Vol. IV, 641)
states that potassium chromate can be prepared by neutralising the
dichromate with potassiiim carbonate.

The present research was undertaken with the view of determining
if the decomposition were quantitative, to investigate the action
of the dichromate on nitrites, and, if possible, to devise a method
of estimating carbonates in the presence of nitrites.

Experimental.

I. — The Action of Potassium Dirlirnmcite on Carbonates.

The apparatus used consisted of a conical flask about 300 c.c,
capacity, fitted with a tap funnel, and a reflux condenser, the top
of which was connected with a series of drying tubes, followed by
potash bulbs communicating through a calcium chloride tube with
an aspirator. About 1 gram of the carbonate, in the solid state
or in solution, is placed in the flask, and 5 per cent, aqueous
potassium dichromate is added. The solution is heated gently to
boiling, and is kept boiling for two or three minutes. Carbon
dioxide is evolved fairly uniformly up to the boiling point. About
1200 c.c. of air are drawn through the apparatus at the end.

It was found that soluble carbonates are quantitatively decom-
posed in this way, and that insoluble carbonates, in a very fine
state of division, are completely decomposed on boiling for five or
ten minutes, provided that the resulting chromate is soluble in the
liquid, otherwise decomposition is incomplete.

In the following table, a was pure sodium carbonate (from the
bicarbonate); h, calcite; c, "magnesia alba ponderosa " ; d, nickel
carbonate, c and d were also analysed in the same apparatus, using
sulphuric acid.

Weight of
carbonate

Carbonate. in grams.

a 1-0895

a 1-0362

a 0-7894

h 0-3187

b 0-4365

c 1-1967

c 1-1389

c (using acid) 1-2787

d 0-4064

d 0-2877

d (nsing acid) 0-8506

Carbon

dioxide,

Per-

gram.

centage.

Calculated

0-4519

41-48^
41-55 \
41-55 j

0-4.305

41-51

0-3280

0-1400
0-1929

43-931
44-19 j'

43-96

0-4339

36-26

0-4115

36-13

0-4631

36-22

0-0725

17-84

0-0517

17-97

0-1556

18-29

PRESENCE OF NITRITES, SULPHIDES, OR SULPHITES. 1493

Copper carbonate gave 769, 7"47, and 785 per cent, of carbon
dioxide, using dicbromatc, and 911 and 905 per cent, using acid.
Barium carbonate was only partly decomposed by potassium
dichromate.

The cliromates of nickel, copper, and barium are sparingly soluble
or insoluble.

II. — Tlie Action of I'ufassiu/n Dic/iro/iiafc on Nitrites.

On fusion with dichromate, nitrites evolve oxides of nitrogen ;
the residue contains chromate, and shows no sign of reduction even
when the nitrite is in excess. Strong solutions, containing a
dichromate and a nitrite, evolve red fumes on boiling, and no
reduction is observed unless the boiling be prolonged, when a
slight brown precipitate appears (probably chromium dioxide).

Excess of a strong acid produces immediate reduction — to
chromium dioxide with excess of dichromate, to a chromic salt with
excess of nitrite — but as much as one-fifth equivalent of free acid *
produces no reduction in half an hour. Distillation of a dilute
solution of a nitrite with potassium dichromate gives an acid
distillate having the reactions of nitrous acid ; no nitrous fumes
appear when the concentration of the nitrite is less than 5 per cent.
The yield of nitrous acid increases with the concentration of the
nitrite, but seems to be independent of that of the dichromate,
provided that at least a quantity equivalent to the nitrite of the
latter be present.

Nitrous acid is said to decompose according to the equation :
3HN0o = 2N0 + HNO3 + HoO.

That it may be permissible to estimate carbonates in the presence
of nitrites, it is necessary to determine to what extent this decom-
position proceeds under the conditions of the experiment. This
was done in two ways. First, the quantity of nitrous acid which
can be distilled from a solution containing a nitrite and a
dichromate was determined; and second, the qviantity of nitric
oxide evolved was measured.

The volume of standard permanganate solution required to
oxidise the distillate was compared with that necessary to oxidise
the original nitrite solution. It was found more satisfactory to
finish the titration with oxalic acid, as, in the usual method, when
excess of permanganate is present, a precipitate of hydrated
peroxide of manganese is liable to be formed on warming, and
this is only slowly removed by oxalic acid (compare Harcourt and
Esson, Phil. Trans., 1866, 156, 193).

* The nitrite contained more than 97 per cent, of sodium nitrite.

1494. MARLE: THE ESTIMATION OF CARBONATES IN

The best yield of nitrous acid was obtained when 100 c.c. of
distillate were collected at a time, and the solution in the flask
was made up to the original volume after each distillation.

After about 30 per cent, of the nitrous acid had passed over,
successive distillates contained very slowly diminishing quantities
of nitrous acid, indicating that about 90 per cent, of the total
might be expected in about six litres of distillate. Mr. Chapman
Jones, in 1899 (results unpublished), by distilling slowly, obtained
9r2 per cent, of the nitrous acid in the distillate, the residue in
the flask containing practically no nitrite. Loss about 10 per
cent.

To determine if appreciable quantities of nitric oxide are carried
over during distillation, two series of experiments were made.

(1) An apparatus was employed by moans of which 100 c.c. of
liquid could be distilled over in an atmosphere of carbon dioxide,
the gas formed being collected in a nitrometer over concentrated
potassium hydroxide solution. Nitric oxide corresponding with
about 3 per cent, of the nitrite was obtained.

(2) A modification of the apparatus described by Meisenheimer
and Heim {Ber., 1905, 38, 3834) was used. Ten c.c. of 12 per
cent, potassium nitrite and 25 c.c. of 1*2 per cent, potassium
dichromate were placed in the flask, the air was disjDlaced by
carbon dioxide, and the liquid was distilled almost to dryness ; the
gas was collected in a nitrometer. A condenser was inserted
between the flask and the nitrometer, as the hot nitrous acid was
found to act on the mercury of the nitrometer. Nitric oxide
corresponding with about 5 per cent, of the nitrite was obtained.

Since, under these rather severe conditions, the quantity of
nitric oxide set free is so small, that liberated during an actual
estimation of a carbonate in tlie presence of a nitrite would be
negligible. Further, part of the nitric oxide dissolves in the
dichromate solution, and gives, on boiling, the slight darkening
of colour and precipitation noted above.

III. — The A ction of Potassium Dichromate on Carbonates and
Nitrites together.

From the above experiments, it would seem that it is theoretically
possible to estimate carbonates in the presence of nitrites, provided
that good condensation of the nitrous acid is ensured (compare
Marie, Proc, 1909, 25, 74).

Equal portions of a solution of pure sodium carbonate, each
containing 1'0023 grams, mixed with 25 c.c. of 5 per cent, aqueous
sodium nitrite, were boiled with 100 c.c. of 5 per cent, potassium
dichromate in the apparatus described on p. 1492.

PRESENCE OF NITRITES, RULPIIIDER, OR SULPniTES. 1495
The following results were obtained :

Sodiuiu carbonate,

Carbon dioxide,

grams.

Nitrite, grains.

grara .

Percentage

1 -OO'JS

1-25

0-4152

41-42

1-0023

1-25

0-4156

41-45

—

1-088

0-0170

1-56

—

2-176

0-0330

1-52

—

2-176

0-0347

1-60

0-4250

0-4419

0-1824

21 00

0-4250

0-4419

0-1837

21-14

1 062(5

1-1047

0-4562

21-14

1 -0626

1-1047

0-4542

21 -05

2-1252

2-2093

0-9075

21-00

I

In the first two experiments sodium nitrite free from carbonate
was used, in the remainder an impure potassium nitrite was
employed. The mean of the last five determinations gives I'SO
per cent, of carbon dioxide in the nitrite. Hence a very fair
accuracy is possible even when the nitrite is greatly in excess.

IV. — The Acfion of Potassium Bichromate on Sulphites and
Carbonates together.

Aqueous solutions of alkali sulphites reduce potassium dichromate
slowly in the cold and rapidly on boiling; no gas is evolved.

In the presence of a soluble carbonate, dichromate being in
excess, an olive-green precipitate forms on standing in the cold.
The filtrate contains no sulphite, and no tervalent chromium. The
precipitate, thoroughly washed with cold water and dried over
concentrated sulphuric acid in a vacuum, is of a brownish-green
colour, insoluble in cold v/ater. On boiling with water, carbon
dioxide is evolved, and a brown powder resembling chromium
dioxide remains, but a carbonate is still present.

One specimen gave on analysis: CroO3 = 50'34; Alkalis = 8'7;
002 = 1518; HoO = 23 per cent., and traces of sulphate and
chromate.

The substance is an impure basic carbonate of chromium, and,
since chromium chromate is not soluble in potassium dichromate
solution, it resembles the carbonates of nickel and barium in
being incompletely decomposed by potassium dichromate solution.
Experiment shows that only 98 or 99 per cent, of the carbon
dioxide of a carbonate is expelled by dichromate in the presence of
a sulphite, even with prolonged boiling.

The method of estimation is therefore modified by boiling the
mixed solution in the apparatus, and then adding dilute sulphuric
acid to complete the reaction. No sulphur dioxide is liberated.

Sodium sulphite almost always contains carbonate, so that a
preliminary series of experiments was made to determine the

1496 MARLE : THE ESTIMATION OF CARBONATES.

amount of carbonate present. Assuming this quantity, subsequent
experiments gave good results for the carbon dioxide in sodium
carbonate :

50'038 grams of sodium sulphite in 250 c.c.

c.c. of solution.

Carbon dioxide, gram.

Pe

s

centage.

2.'5

0-060.^

1-21

25

0-0622

1-24

25

0-0713

1-42

50

0-1052

1 -05 Mean

1-23

It was found impossible to use larger quantities of sulphite
because of the bulky precipitate which formed in the flask.

7-5339 Grams of pure sodium carbonate and lO'OOTG grams of
sodium sulphite were dissolved in 250 c.c, and 25 c.c. of this
solution were boiled with dichromate. The carbon dioxide due to
the carbonate in the sulphite is assumed to be 0-0123 gram in each
case:

Carbon dioxide Percentage of

Carbon dioxide, from sodium carbonate, carbon dioxide in
gram. gram. sodium carbonate.

0-3261 0-3138 41-65

0-3269 0-3146 41-76

0-3253 0-3130 41-55

NaX'Oa requires 41-51

V.^ — The Action of Potassium Dichromatt on Carbonates and
Sulphides together.

Sodium sulphide reduces dichromate at once, no gas is evolved,
a precipitate of sulphur and chromium hydroxide forms, and the
solution is yellow ; when dichromate is added in excess, the filtrate
decomposes carbonates.

On distillation with excess of dichromate, a neutral liquid is
produced containing a white precipitate of svilphur, but no hydrogen
sulphide, so that when a reflux condenser is used no gas passes on
into the apparatus.

Insoluble sulphides are not affected by dichromate solution. In
the presence of a soluble carbonate, a basic carbonate of chromium
is formed; so that it is necessary to add dilute acid after boiling
to ensure complete decomposition of the carbonate.

Pure sodium sulphide solution free from carbonate was prepared,
and 5 c.c. of this (a 6 per cent, solution) were added to the pure
sodium carbonate used.

Sodium carbonate, Carbon dioxide,

grams. gram. Percentage.

0-7534 0-3139 41-66

1-3740 0-5719 41-62

Na^COg requires 41-51

THE PREPARATION OF SOME REFRACTORY METALS. 1497

Conclusions.

Carbonates may be estimated by means of potassium dichromate
in the presence of nitrites. The nitrous acid formed during the
operation is condensed in a reflux apparatus, and the quantity of
nitric oxide (due to decomposition of the nitrous acid) carried off
by the carbon dioxide is negligible under the conditions of the
experiment.

If sulphides or sulphites are present, a basic carbonate of
chromium is formed which is not completely decomposed by
potassium dichromate, so that the action must be completed by the
addition of dilute sulphuric acid towards the end of the operation.

My thanks are due to Mr. Chapman Jones for his kindness In
suggesting the above problems, and for the loan of the notes of
work carried out in his laboratory.

Chemical Department,

Hautley Umvek.sity College,

SoUrHA.MPTOX.

CLXXI. — The Preparation at High Temperatures of
some Refractory Metals from their Chlorides.

By John Noeman Pring and William Fielding.

Very little has been published on the nature of the reactions
whereby the metals tungsten, molybdenum, chromium, tantalum,
and the non-metals, silicon and boron, may be obtained in the
pure state by the dissociation of their chlorides or by decom-
position of these by hydrogen at high temperatures. These
reactions are made use of on a large scale in lamp manufacture
for the preparation of filaments of refractory metals, and endeavours
have been made to apply the method to the coating or " flashing "
of carbon lamp filaments with elements which give a more favour-
able selective radiation than carbon.

The process devised by Just and Hanaman {Electrical Review,
1908, 63, 1070; Electrochem. and Metall. Ind., 1909, 7, 24) for
the preparation of tungsten filaments consists in exposing ordinary
carbon filaments heated to bright redness by an electric current
to an atmosphere of a volatile tungsten compound, such as a
chloride or oxychloride. A uniform layer of tungsten is thereby

VOL. XCV. 5 Tt

1498

PRING AND FIELDING : THE PREPARATION OF

deposited on the filament. This is then converted into carbide by
raising the temperature, and is then decomposed and all the
carbon removed by heating in an atmosphere of hydrogen con-
taining a small percentage of water vapour. In this way a sintered
filament of pure tungsten is left in tubular form.

The object of this investigation was to ascertain the conditions
necessary for causing the separation of tungsten, molybdenum,
chromium, silicon, and boron from the chlorides, by means of a
heated carbon rod, to study the extent to which they react with

i 'l

the carbon at different temperatures, and to examine briefly the
photometric properties of the rods coated with these deposits.

The apparatus used consisted of a tubular glass flask of about
2 litres capacity, which contained a carbon rod usually of 5 mm,
diameter and about 9 cm. long (Fig. 1). To allow of electrical
heating, this rod was, at each end, mounted in water-cooled brass
tubes, fitted with graphite end pieces, which were fixed by electro-
coppering the ends and soldering them into the brass plugs which
closed the water-cooled tubes. No difficulty was in this way
experienced in ensuring good electrical contact between the carbon
and the graphite ; arcing was quite avoided even with high-current
densities, and the rod could afterwards be removed without any
loss.

SOME REFRACTORY METALS FROM THEIR CHLORIDES. 1499

The water-cooled brass tubes were fixed in the side-tubes of the
flask by means of wax, which proved to be quite air-tight even
during the heating of the rod.

With a rod 7 cm. long and 0'5 cm. diameter in an atmosphere
of hydrogen, and using a current of 160 amperes (direct current)
at 18 volts, a temperature of 2200° could quite safely be attained
in this apparatus, and the flask could be evacuated with the rod
at 2100°. The experiments carried out with this apparatus con-
sisted in heating the rod to various known temperatures, exposing
it to the vapours of the various chlorides, either alone or in
presence of hydrogen, and examining the deposits obtained.

In studying the reaction between volatile chlorides and hydrogen,
the latter, before passing into the flask, was led over the surface
of the chloride contained in a bulb which was kept in a water-bath
to control the temperature, and hence the amount vaporised.

In cases where the chlorides were used alone, these were admitted
intermittently into the vacuous flask, which was again exhausted
to remove the products of decomposition. In experiments with
the solid chlorides, such as tungsten and molybdenum, the sub-
stance was placed in a graphite crucible arranged 1 to 3 cm.
underneath the rod, and thus vaporised by the radiant heat. In
this case, pumping was continued throughout the process to maintain
a diminished pressure and remove the gaseous products of decom-
position. Temperature readings were taken by means of the
\Vanner optical pyrometer, sighted on to the carbon rod. The
deviaticm from " black body " radiation with these heated rods
was measured by checking the pyrometer readings against those
given by a thermo-junction arranged in the interior of a hollow
rod. The difference at 1250° was found to be not above 15°
(Greenwood, Trans., 1908, 93, 1486).

In the course of an experiment, the apparatus was first com-
pletely exhausted by means of a Topler pump, and then, while the
glass was quite clear, a series of readings was taken, in each case,
of the temperatvxres corresponding with the number of watts
expended in the rod. Throughout each run the watts were
kept as constant as possible in order to secure a uniform
temperature.*

The first indications of the deposition of metal were usually
given by a fall in the resistance of the rod, which continued as
the thickness of this coating increased, and also in some cases,

* In cases where a large change in the resistance of the rod took place during
the deposition, a certain error in the temperature estimates would arise through
tlie unknown contact resistance between the carbon rod and the graphite support-
ing plugs. "When the rod is carefully fitted, however, there is evidence to show
that this contact resistance is low. An idea of the current consumption needed fo

5 F 2

] oOO PRING AND FIELDING : THE PREPARATION OF

especially with tungsten and molybdenum, by a marked increase
in the luminosity of the rod.

Boron.

The decomposition of boron trichloride was brought about by
mixing with an excess of hydrogen and allowing to circulate
through the apparatus at atmospheric pressure. At 1500° a slight
deposit of free boron occurred, which fell off on cooling. At 1750°
the rod began to be coated with a smooth shell deposit of boron
carbide, which could afterwards be peeled off, and was identified
by its characteristic hardness, enabling it to scratch a carborundum
crystal. Very little change in resistance took place during this
deposition.

At 1950° the deposit of carbide took place more readily, was
more adherent, and assumed a nodular form, whilst at 2150° the
deposit began at several centres and expanded into large, crystalline
masses, which grew outwards until they met and formed an outside
casing in a zone of lower temperature.

In this case, the crystals were very loosely attached to the rod,
only adhering at a few small points.

At 2200° it was no longer possible to obtain a complete deposit
of carbide on the rod, but a sooty formation of this substance,
together with free boron, took place on the water-cooled brass
holders. This dispersion of the boron carbide under these con-
ditions is probably not due to simple volatilisation, as the melting
point of this compound has been found, in the course of some
unpublished work, to be as high as 2350°, and the substance does
not undergo any considerable decomposition or volatilisation below
2800°.

At temperatures above 2000° the boron appears to exert a
catalytic effect in converting the carbon into graphite, as, in these
cases, a layer of very soft graphite was formed underneath the
deposit and extended about half way through the rod, while a
thin core in the centre apparently remained as unchanged carbon.
The experiments made with boron trichloride are tabulated below.
In each case the carbon rod used was of 5 mm. diameter, 7 to 9 cm.
long, and 5 to 8 grams of boron chloride were used.

these experiments is shown in the following table, where a rod 0'49 cm. diameter

and 5 "5 cm. long was calibrated for temperatures up to 1760°.

Amps. Volts. Watts. Temp.

50 7-7 385 1220°

60 8-7 522 1355

70 9-6 672 1470

80 10-5 840 1590

90 11-3 1017 1690

96 11-6 1113 1760

SOME REFRACTOllY METALS FROM THEIR CHLORIDES. 1501

I. — Boron trichloride used with excess of hydrogen at atmospheric

'pressure.

Thickness of
Lnngth of Duration of layer of BgC
Temp. rod, cm. run, mins. formed, mm. Nature of deposit.

1800° 9 45 0-2 Smooth skin deposit.

• 1950 7'5 35 0"6 Nodular adherent deposit.

2200 7-0 23 — Sooty deposit of BgC and

boron on tubes. Few
crystals on rod adhering
by points.
1900 8-6 25 0-5 Shell deposit studded

with crystals.

II. — Boron trichloride, with small quantity of hydrogen, at about
half an atmosphere pressure.

Duration of Boron tricliloride
Temp. run, niius. used, grams. Nature and weight of deposit.

1780" 80 13-05 Hard adherent shell deposit

with corrugated surface.

"Weight 0-493 gram of BgC.

1900 50 6-21 Small, hard crystals of BgC,

weight 0 148 gram.

Silicon.

Reactions were conducted with silicon tetrachloride in a manner
similar to the above. The silicon chloride was, in some cases,
admitted alone after evacuation of the globe, in others was mixed
with hydrogen, and in some with hydrogen and benzene vapour
(compare " Helion " filament, Electrician, 1907, 58, 567; Trans.
Electrochem. Soc, 1907, 11, 375).

Using silicon tetrachloride alone, no considerable deposit was
obtained. With an excess of hydrogen, the silicon began to deposit
at 1700°, forming a thin shell layer of silicon carbide, and above
this, hard crystals of free silicon, although silicon is known to
combine with carbon at 1300° (Pring, Trans., 1908, 93, 2104).

At 1925° the whole of the deposit was in the form of carbide.

When the reaction was conducted in presence of benzene vapour,
the deposit obtained was found to consist of silicon carbide (SiC),
together with a varying excess of carbon. The method adopted,
in most cases, for examining the nature of the deposits consisted
in treating the substance with hot potassium hydroxide solution,
whereby free silicon is dissolved. Free carbon was next removed
by igniting in air, and the silicon carbide left unchanged. Analysis
of this was in some cases effected by igniting in chlorine,
ascertaining the loss in weight, then igniting in oxygen, and
absorbing the carbon dioxide formed in a weighed potash bulb.
The results of the experiments are given in the following table.

Mixture
admitted.

Length
of run.

Tempera
ture.

SiCl^ + Ho

60 luiiis.

1700"

SiCl4 alone
SillCl.5 alone

75
35

1700
1830

SiHCl3 + SiCl4

40

2030

CfiHe + H^ + SiCl^

40

1850

CeHg + Ha + SiCl,

40

2000

1502 PRING AND FIELDING : THE PREPARATION OF

The dimensions of tlie rod iiscd were, in each case, 9 cm. in
length and 05 cm. in diameter. No considerable change in the
resistance of the rod took place during the deposition.

Nature and weight of dejiosit.
Shell layer of Si, studded with very
small, hard crystals 0'05 mm.
thick.
SiClj + Hj 75 ,, 1S30 Shell layers studded with very hard

crystals of Si. Total weight de-
posited 0'248 gram.
SiClj + Hg 60 ,, 1925 Large, crystalline masses of SiC de-

posited. Weight, 0'876 gram ;
graphite core, 0"485 cm. left.
SiClj + Hj 35 ,, 2000 Loosely attached crystals of SiC;

weight, 0'816 gram.
No deposit.

No deposit. Rod evolved some gas
on treating with hot potash solu-
tion.
Considerable gas evolution on treat-
ing rod with hot potash .solution.
Very smooth shell deposit of SiC.

0'02 gram.
Large masses of loosely adhering
crystals of SiC, 0"15 cm. thick.
(These, on analysis, were found to
consist of SiC with excess of car-
bon, namely, Si = 60 '2 and C =
36 "1 i^er cent.)
CeHg + Hj-fSiCli 60 ,, 2000 Crystals containing Si = 63 "2 per

cent.
CgH6-^H2 + SiCl4 2 hrs. 1870 Depcsit of 1 76 grams. _ No free Si.

Combined Si in deposit =64*4 per
cent.
C6H6-fH2-l-SiCl4 1^ ,, 1750 Bright crystalline depcsit of 1-59

grams. Combined Si = 65 '5 per
cent.
C6H6-hSiCl4 1^ „ 1700 Dullblack, crystalline deposit, 1-35

grams.

The deposits obtained when silicon tetrachloride is decomposed
in conjunction with hydrocarbons appear to consist of silicon
carbide, SiC (which contains 70'3 per cent, of silicon), with an excess
of carbon.

Tungsten.

Tungsten hexachloride was obtained as purple crystals con-
taminated with traces of the red oxychloride by passing dry
chlorine over metallic tungsten, heated in a Jena glass tube. This
was luted into a wider glass tube, to serve as condenser for the
sublimed chloride. Great care was taken to keep everything dry
and exclude moisture. The chloride, which volatilises at 346°, was
placed in a graphite crucible of 3"6 cm. height, 2 cm. internal
depth, 26 cm. internal diameter, and 3'2 cm. external diameter.

SOME REFRACTORY METALS FROM THEIR CHLORIDES. 1503

The crucible was fixed on to the end of an iron rod, as shown in
Fig. 2. This and a second rod passed through two holes in the
stopper at the neck of the flask, and permitted an adjustment of
the distance from the heated carbon rod.

In some experiments, to facilitate further the heating of the
crucible, a spiral of platinum wire was wound round, the ends
being joined on to the two iron rods. A sheet of mica was placed
around the crucible for insulation. The flask was then exhausted
by means of a Topler pump, and the rod heated. In some cases,
hydrogen was introduced, but this was not found to assist the
reaction. Probably owing to difiiciilties in causing volatilisation,
there was usually no deposition when the pressure of gas inside the
flask exceeded 2 cm.

A coating of metal on the rod began to take place at 1000°
under a pressure of 1 cm. When the deposition began, an imme-
diate fall in the resistance of the rod occurred, in many cases
amounting to more than half the original value. The current was
adjusted throughout each run so as to keep the watts as constant
as possible. The deposits were, in all cases, of a silver-white colour,
adherent and smooth, and their nature was ascertained by their
hardness, the pure metal being comparatively soft and unable to
mark glass, whilst the carbide is very hard and scratches glass
readily (compare Moissan, " The Electric Furnace," London, 1904,
p. 160).

In the experiments tabulated below, the crucible was placed at
a distance of about 1 to 1*5 cm. from the rod.

Watts
consumed.

Resistance

before and

after (ohm.)

Duration
of experiment.

Nature and w(
deposit

sight of

Temp.

grams.

2050°

2170

0
0

112\
122J

60 niins.

WeC

0-35

1530

800

0
0

260\
141/

90 „

AV

069

1770

1100

0
0

149\
104/

60 „

w«c

0-18

1550

610

0
0

105)
076/

60 ,,

w«c

0-86

1580

650

0
0

163V
147/

2^ hrs.

W

0-1

1500

580

0
0

260\
122/

90 mins.

W + WgC

—

1400

420

0
0

23 \
10 /

60 „

w

1-13

1200

250

0
0

252)
089/

90 „

w

1-1

From this it is seen that metallic tungsten is deposited from
the chloride at temperatures between 1000° and 1500°, and that
tungsten carbide is formed above this temperature.

1504.

PRING AND FIELDING: THE TUEPARATION OF

MoIi/bcIc?ium.

Reactions with molybdenum tetrachloride and pentachloride,
prepared by passing dry chlorine over the heated metal, were
carried out as with tungsten hexachloride. The graphite crucible
was placed at a distance of 1"5 cm. from the heated rod, and the
following results were obtained.

Watts

Resistance (o

Temp.

consumed.

before and a

1600°

750

0
0

2001

ur,f

1480

520

0
0

140\
139/

1330

380

0
0

198 "I
100/

1280

308

0
0

IfjS)
098/

experiment.
60 mins.

Deposit.

60

80

/Crystalline deposit of
\ MogC (white).
/ Hard, smooth deposit
\ of M02C (white).

{Metal with carbide in
places, 0"3 f:^am.
Bright smooth metallic
deposit, free from car-
bide.

Metallic molybdenum is thus separated from the chloride at
temperatures below 1330°, the carbide being formed above this
temperature.

Chromium.

An endeavour was made to obtain deposits of chromium, using
the volatile oxychloride, CrOgCl,- The temperature of the rod was
slowly raised up to 2000°, and the pressure of oxychloride vapour
varied, but no visible deposit of metal took place.

On admitting hydrogen, the mixture detonated, and chromium
chloride was deposited on the sides of the flask.

The carbon rod became considerably pitted during the experi-
ment, and on treating with aqua regia was found to have taken
up traces of chromium, but no distinct coating of metal or carbide
could be obtained by this reaction.

Removal of Carbon from the Carbides of Tungsten and
Molybdenum,.

The above experiments show that it is possible to prepare the
metals tungsten and molybdenum by the dissociation of their
chlorides at high temperatures. Any desired thickness of metal
can, in this way, be obtained as a deposit on the carbon heaters.
Endeavours were made to remove the metal deposits from the
carbon rods and obtain them in the form of tubes, and, at the same
time, to remove any trace of combined carbon from the metal.
The authors were not successful in preparing tubes of these metals,
but it was found that if the deposition of tungsten and molybdenum
from the chlorides was allowed to take place on carbon rods in

SOME REFRACTORY METALS FROM THEIR CHLORIDES, 1505

presence of 1 to 2 c.c. of water vapour, the flask being otherwise
vacuous, that the metal deposited at all temperatures was free
from carbon, although less adherent than that prepared in absence
of water vapour (compare Just and Hanaman's process, lor. cit.).

Photometric Measurements.

Some approximate measurements were made on the relative
efficiencies of these metal-coated rods as sources of light at different
temperatures.

The nature of the light radiated from heated filaments and the
emissive properties of tungsten and other refractory metals have
been extensively investigated by W. W. Coblentz [Bull, of the
Bureau of Standards (Washington), 5, No. 3, p. 339].

The apparatus used in the present measurements was of the
same type as that described above. The rods were mounted in
the well-cleaned glass globe in which they had been prepared. An
air-tight connexion between the water-cooled holders and the side-
tubes of the globe was made with soft wax, and the apparatus
evacuated to a pressure of 4 mm. of mercury.

A current was then passed through the rod and adjusted so that
a known number of watts was expended, and the light radiated
was compared photometrically with that from a standardised
carbon filament lamp. A scale of " black body " temperatures
corresponding with the number of watts consumed by the rod was
derived ojDtically from a carbon rod of the same size and heated
under similar conditions.

In each experiment with the coated rods, readings were taken at
two different temperatures, namely, 1600° and 1775°. The chief
sources of inaccuracy in this work were probably the variation in
the end contact resistance of the carbon, and also the fact that
small, thin rods had to be employed to avoid using a current
greater than 100 amperes, hence any variation in the thickness of
the deposits would alter sensibly the amount of radiating surface.
The carbon rods were 5"5 cm. long and 4"0 mm. in diameter, and
deposits 0'25 mm. thick were generally obtained, although in the
case of silicon this amounted to 0"75 mm.

During the heating, a small, steady evolution of gas took place.
This effect has been observed before in experiments in which carbon
rods alone were used, and is due either to occlusion of gas by the
carbon, or else to the reaction of the carbon with water vapour
condensed on the surface of the glass. By pumping at intervals,
the pressure could be kept at 4 to 5 mm.

The photometer used was of the Lummer-Brodheim type, and the

Tungsten
deposit.

Molyb-
douuni
deposit.

Boron
deposit.

3-00

2-97

6-06

6-27

1-16

1506 BEST AND THORPE : THE FORMATION AND

following comparative results were obtained, tlie values being
expressed in terms of the standardised lamp.

Carbon
rod.
Luminous intensity with 332 watts,

temp. 1600" 1-01

Luminous intensity with 465 watts,
temp. 1775° 3'40

In the case of the rod coated with silicon carbide, the value
obtained was as low as 0'91. This is perhaps largely accounted
for by the greater diameter of the coated rod (5'5 mm.), although
the result is in great disagreement with the supposed high efficiencies
of silicon-coated filaments.

With the boron and silicon deposits, the luminosity was not
sufficiently high for measurement with the lower amount of power,
so that results could only be obtained at the one temperature.

Electko-Chemical Laboratory,
The University,

Manchester.

CLXXII. — The Formation and Reactions of Imino-
coinpounds. Part X. The Formation of Imino-
derivatives of Pyrrole and of hoPyn^ole from
A mino-nitriles.

By Stanley Robert Best and Jocelyn Field Thorpe.

It has been shown in Part IX of this series (Trans., 1909, 95,
685) that in an open chain of five carbon atoms having a
nitrile group attached to the a- and 5-carbon atoms respectively,
there is a considerable tendency to the formation of the cyclo-
pentane ring. So great is this tendency, especially in the presence
of sodium ethoxide or an alkaline sodium compound, that in one
example investigated it was not found possible to isolate the open-
chain compound, as all reactions which should have yielded it
gave instead the corresponding derivative of cycZopentane.

Thus, ethyl a5-dicyanovalerate (I) could not be isolated from
the product of the action of sodium ethoxide on ethyl a5-dicyano-
adipate (II), the sole product being ethyl 2-imino-3-cyanocyc^o-
pentane-1-carboxylate (HI) :

CH^-CHCCKj-CO^Et CH^-CH^-CN CH^ CH(CN)

CH2-CH(CN)-C02Et CH2-CH(CN)-C02Et CH2'CH(C02Et)^ '
(I.) (II.) (III.)

REACTIONS OF IMINO-COMPOUNDS. PART X. 1507

In the same manner, it was found by Moore and Thorpe (Trans.,
1908, 93, 165) that o-phenylenediacetonitrile (IV) passed into
j3-imino-a-cyanohydrindene (V) when its solution in alcohol was
treated with a trace of sodium ethoxide:

'CHo-CN . ^, -„ ^CHo

(IV.) (V.)

This transformation is probably, therefore, general to all dinitriles
of this type.

It is, of course, well known that the five-membcred ring contain-
ing one nitrogen atom and four carbon atoms is also easy of
formation, as is shown by the formation of lactams from y-amino-
acids, and it therefore seemed of interest to ascertain whether a
cyclic compound of this type could be formed through the imino-
compound in the same manner as the cr/f^opcntane ring.

There are numerous examples of this kind which could be used
for the purpose of ascertaining this fact. For example, y-amino-
butyronitrilo (VI) miglit, on treatment with sodium ethoxide, pass
into iminopyrrolidone (VII), and o-aminophenylacetonitrile (VIII)
into imino-oxindole (IX).

CH^-CHg-NH^ CH^ CH^.

CHg-CN CHg-qiNH)'

(VI.) (VII.)

J>NH

(VIII.) (IX.)

It is proposed to investigate the conditions of ring formation
from these two typical compounds in the near future, but while
experiments on their formation were being instituted it was
decided to investigate a similar case which was ready to hand,
namely, by preparing an amino-compound of this type in the
following way.

Ethyl )8-imino-a-cyanoglutarate (X) has been prepared by Baron,
Remfry, and Thorpe (Trans., 1904, 85, 1737), and has been shown
to react with sodium ethoxide, yielding a sodium compound repre-
sented by (XI) :

^rr.p/CHj-CO^Et T^^.p^CHNa-CO^Et

■^•^^CH(CN)'-C02Et ^^-^* '^CH(CN)-C02Et

(X.) (XL)

The large number of imino-compounds which we have prepared
since the description of this substance was published has enabled
us to gain further knowledge of its structure, and to explain the
reason why the presumably more acidic hydrogen atom attached to
the eyanoacetic residue contained in it is not replaced by the

1508 BEST AND THORPE: THE FORMATION AND

sodium atom instead of one of the hydrogen atoms of the methylene
group as rei>resented above. This explanation properly belongs to
a subsequent paper which we propose publishing on tue
tautomerism of amino-imino-compounds, but, in order to render
the present argument clear, it is necessary here to allude to certain
conclusions, which may be summarised as follows.

From our experiments described in the previous parts of this
series, it appears that imino-compounds may be divided into three
classes.

Class I. — Comprising those compounds which have three (and
presumably also four) negative groups attached to the carbon
atoms adjacent to the carbirriino-group, and having therefore the
general formulae :

CHXo-C(:NH)-CHX2 and CHoX-C(:NH)-CHX2.

Class II. — Comprising those compounds having two negative
groups attached to the two neighbouring carbon atoms, and which
therefore can have either one of the two formulae :

(a) CHoX-C(:NH)-CHoX or (h) CH3-C(:NH)-CHX2.

Class III. — Comprising those compounds having one negative
grouji attached to one of the carbon atoms adjacent to the
carbimino-group, and which therefore have the general formula :

ch3-c(:nh)-ch2X.

Now, compounds containing the imino-group react, as Collie
(Trans., 1897, 71, 303) has shown in the case of ethyl )8-imino-
butyrate, NH!CMe'CH2'C02Et, with dry hydrogen chloride in dry
ethereal solution forming salts of the formvxla !CINH,HC1, which,
when treated with water, yield the ketone and ammonium chloride,
thus :

:c:nh,hci + H2O — > :co + nh,ci.

These compounds are therefore at once hydrolysed by dilute
hydrochloric acid to the corresponding ketones. The members of
Class III, to which, of course, ethyl /3-iminobutyrate belongs, all
behave in this way.

The imino-compounds of Class I, however, form isomeric salts
with dry hydrogen chloride, which, when treated with water,
dissociate, regenerating the imino-compound. These salts there-
fore have the formula JC'NHgjHCl, and react with water, thus:
iC-NHg.HCl + HgO -> :C-NH2 + HCl + Hfi

The imino-compounds of this class are therefore not hydrolysed
by hydrochloric acid, and it is evident that they are amino-
compounds which may have one or other of the following formulae :
CH2X-C(NH2):CX2 or CHX:C(NH2)-CHX2.

It is, moreover, evident that the first of these formulae is the

REACTIONS OF IMINO-COMPOUNDS. PART X. 1509

correct one, because, taking the case of ethyl )3-imino-a-cyano-
glutarate, in which the two forms would be represented by formulae
(XII) and (XIII) :

ssi±2 ^^C(CK)-C02Et -"^2 '^^CH(CN)-C02Et

(XII.) (XIII).

it is evident that formula (XII) represents its structure, because
in a compound of formula (XIII) the hydrogen atom of the cyano-
acetic residue marked (*) would most certainly be replaced by
sodium on treating the compound with sodium ethoxide.

Our conclusions are then, briefly, that imino-comjoounds of
Class III are true imino-compounds which show no chemical
evidence of reacting in the amino-form, whereas compounds belong-
ing to Class I are true amino-compounds which exhibit no chemical
evidence of reacting in the imino-form.

As regards the members of Class II, the position is interesting,
because they seem to react as true tautomeric amino-imino-
compounds. Thus they give mixed salts of the amino- and imino-
forms with dry hydrogen chloride, and their hydrolysis to the
ketone by hydrochloric acid is effected after the lapse of a definite
period of time. It is evident that this hydrolysis proceeds only
through the imino-form of the tautomeric compound, but in the
cases investigated it was always complete. The measurement
therefore of the rate of hydrolysis in certain typical cases should
yield valuable evidence respecting the structural conditions con-
trolling the amino-imino-tautomerism. Preliminary experiments
have shown, for example, that compounds of sub-division («) are
hydrolysed much more rapidly than those of sub-division (b).

The whole question is under investigation, and will form the
subject of another communication. It is, of course, probable that
amino-imino-tautomerism is in reality exhibited by all these classes
and is only a matter of degree, but so far as the chemical reactions
of these substances are concerned we have as yet obtained no
evidence in support of this view. We are, of course, aware that
E. v. Meyer (/. pr. Chem., 1895, [ii], 52, 83) has suggested that
the two crystalline forms of j8-imino-a-cyauopropane are represented
by the formulae :

NHiCMe-CHo-CN and NHo'CMerCH-CN,

but there seems to be little evidence in support of this suggestion,
because it is apparent that no reliance can be placed on the
evidence afforded by the formation of the large number of
derivatives of aminopyridine from this substance recently described
by E. V. Meyer {Chem. Zentr., 1908, ii, 591). It is well to

1510 BEST AND THORPE: THE FORMATION AND

remember that when a compound undergoes intramolecular con-
densation involving, in the first instance, the production of an
open-chain condensation product, no trustworthy evidence can be
adduced respecting the structure of the simpler molecule. More-
over, the two forms of )8-imino-a-cyanopropane react towards dry
hydrogen chloride in precisely the same manner, and it is therefore
probable that they are physical isomerides analogous to the two
forms of ethyl j8-iminobutyrate, NH'-CMe-CHg-COoEt, which have
been isolated and investigated by Behrend {Ber., 1899, 32, 544)
and by Knoevenagel (ibid., 853).

The sodium compound of ethyl )3-imino-a-cyanoglutarate * has
therefore the formula COoEt-CHNa-C(NH2):C(CN)-C02Et, and
when treated with iodoacetonitrile should react in accordance with
the equation :
CN-CHal V CO.,EfCHN"a-C(NH2):C(CN)-C02Et -^

' C02Et-CH(CH2-CN)-C(NH2):C(CN)-C02Et + NaT,

although it might be expected that the condensation product, since
it had been formed in the presence of an alkaline sodium com-
pound, would possess a ring structure due to the formation of an
imino-group between the amino- and nitrile-groups, thus:

NH.-C:C(GN)-COoEt _ NH-C:C(CN)-C02Et

CN-CH^CH-C02Et " ■> ^ ' \cH2-CH-C02Et

(XIV.)
in which case the product would be ethyl 2-imino4-carbethoxy-
tetrahydropyrrolidene-5-cyanoacetate (XIV).

At the same time there is also a possibility that ring formation
might take place between a nitrile group and a hydrogen atom
of the methylene group, with the formation of a derivative of
cycZopentane, thus :

CH(C02Et)-CH2-CN 9H(C02Et).CH(CN)

C(NH2):C(CN)-C0,Et C(NH2)==C(C0oEt)'^ "

CH(C02Eb).CH(CN)
C(:NH)-CH(C02Et)^

The condensation between iodoacetonitrile and the sodium com-
pound of ethyl /3-imino-a-cyanoglutarate proceeds smoothly, and
a good yield of a crystalline condensation product decomposing at
205° is readily obtained. The compound possesses the expected
molecular formula CjgHj^O^Ng, and its physical properties show
that it does not possess an open-chain structure. It reacts as an
imino-compound of Class II, and is hydrolysed by hydrochloric
acid to a ketone, melting at 109°, and having the molecular

* For the sake of clearness, it is proposed to retain the name of the iniino-form
for all these compounds iric32)cctive of their amino- or imiuo-structure.

REACTIONS OF TMINO-COMPOUNDR. PART X. 1511

formula C12H14O5N2. It is evident, therefore, that the ketone has
been formed from the condensation product by the hydrolysis of
the group CiNH to CO.

Now, if the condensation product is a derivative of ct/clopentanc,
as mentioned above, this ketone must have one or other of the
formuke (XV) and (XVI) :

CH(CO,Et)-CH(CN) (;)H(C02Et)-CH(CN)

C(:NH)-CH(C02Et)^ CO CH(CO.,Et)^

(XV.) (XVI.)"

CH.,— CH(CN)

CH./CH(COoEt)-^ '
(XVIL)

It should therefore give a violet coloration with ferric chloride, in
the same way as does ethyl 5-cyanocyf/t»pentane-l-one-2-carboxylate
(XVII) (Trans., 1909, 95, 701).

The compound melting at 109° gives, however, no coloration with
ferric chloride, and, moreover, the presence of another amino- or
imino-group cannot be detected in it by the aid of the usual
reagents. It is evident therefore that it cannot possess the cyclo-
pentane structure, and it remained to ascertain whether the
reactions of the condensation product conformed to those of ethyl
2-imino-4-carbethoxyt«trahydropyrrolidene-5-cyanoacetate (XIV).
This, as a matter of fact, they do, and there can be no question
that the constitution of the condensation product decomposing at
205° is represented by this formula.

The reactions of this substance show at once that it is a
tautomeric amino-imino-compound reacting in the two forms :
^„_ .NH-C:C(CN)-C02Et ^ ^„ ^ .N— C:C(CN):C02Et

^^•^<CH2-6H.CO;Et ""' ^^^•^<CH2-6HmEt *

This is evident from the fact that it reacts with cold concen-
trated hydrochloric acid, forming a monohydrochloride (XVIII),
which is, for the most part, dissociated by water, regenerating the
imino-compound, although a small quantity of the ketone is formed
at the same time, indicating that the imino-hydrochloride (XIX)
is also formed :

HCINH .n^N— C:C(CN).C02Et hcI NH-C<r^^"?-^^^^^'^^=^^'
HU.NH. ^<c^^.^^.QQ^^^ ^^^'^^•^<CH2-CH-C0.,Et

(XVIII.) (XIX.)

^^•^^-CH^-CH-CO^Et

(XX.)
With boiling hydrochloric acid it is quickly hydrolysed to the
ketone, the transformation being complete. It is insoluble in
aqueous sodium carbonate solution, but dissolves in alkali

1512 BEST AND THORPE: THE FORMATION AND

hydroxides, forming salts of the formula (XX). Nitrous acid

converts it into the same ketone as is formed with hydrochloric

acid :

.-rrx ^ /N — C:C(CN)-CO.,Et „ ,
NHo'C-^ I ^ '' - _Bot nsoo

CH^-CH-COjEt -^ N==C-CH(CN)-C02Et

NH-C:C(CN)-CO,Et xio^^ <CH,.CH.CO,Et

^^CHg-CH-CO^Et

(XXI.)

It will be noticed that the ketone is represented, not as a
derivative of pyrrole, but of jsopyrrole, namely, as ethyl 2-keto-4-
carbethoxydihydro?sopyrrolyl-5-cyanoacetate (XXI). It is certain,
however, that the pyrrole derivative is first formed, but at the
temperature of the reaction is converted into the derivative of
jsopyrrole. This is evident from the fact that when ethyl 2-keto 4-
carbethoxydihydro/5opyrrolyl-5-cyanoacetate (XXI), which is not
immediately soluble in sodium carbonate solution, is dissolved by
gently warming, the compound which separates on acidifying the
alkaline solution melts at 129°, and differs from the compound
melting at 109° in being soluble in sodium carbonate solution with
effervescence. The two compounds are isomeric, and the former
is converted into the latter on merely boiling with water or on
heating at 100°. There is no doubt that the constitution of these
substances is represented by the formulae:

NH-C:C(CN)-C02Et H°t water N = C-CH(CN)-CO,Et

^CH^-CH-CO^Et <^;^^ ^CH^-CH-CO^Et

M. p. 129°, sol. in NaoCUj. M. p. 109°, insol. in NaaCOs.

, The constitution of the compound melting at 129° follows from
the fact that when the silver salt (XXII) is treated with methyl
iodide a methyl derivative (XXIII) is obtained, which, when
hydrolysed by aqueous potassium hydroxide, yields methylamine
and a compound melting at 104°, which gives a deep red coloration
with ferric chloride and is evidently ethyl hydrogen a-cyano-)8-keto-
adipate (XXIV) :

NAg- C:C(CN)-CU,Et .NMe-C:C(CN)-C02Et

^^CH^-CH-COgEt ^CH^-CH-CCEt ~^

(XXII.) (XXIl'l.)

C0-CH(CN)-C02Et

COjH-CH^-CHg ' ^'^

Xr. + NH,Me + etc.

(XXIV.)

The last-named substance is the same as that which is produced
by the alkaline hydrolysis of ethyl 2-keto-4-carbethoxydihydro-
wopyrrolyl-5-cyanoacetate ^XXI) :

REACTIONS OF IMINO-COMPOUNDS. PART X. lol.'?

N= C-CH(CN)-CO,Et KOH. C0-CH(CN)-C02Et

^CH./CII-CO^Et ^ C0,H-CII,-Cll2

+ NH3 + etc.
(XXI.)

Finally, the ultimate products of the complete alkaline hydrolysis
of all the compounds mentioned above are succinic and malonic
acids :

NH-C:C(CN)-CO.,Et _ C0-CH(CN)-C02Et

"^CH./CH-COaEc ' "^ C02H'CH2'CK2 ~^

With acid hydrolysing agents, ethyl 2-keto-4-carbethoxytetra-
hydropyrrolidene-5-cyanoacetate or its isomeride behaves in quite
a difTcrent manner. It has been shown in Part I of this series
(Trans., 1904, 85, 1740) that when ethyl )8-imino-a-cyanoglutarate
is treated with concentrated sulphuric acid, ethyl glutazine-
cai'boxylate is formed. The same reaction occurs with the mono-
methyl derivative (XXV), in which case ethyl methylglutazine-
carboxylate (XXVI) is formed, thus :

j.^ ,^^C(CO,EtyCN jj.^^C(CO.,Et)-C(OH)=^^

(XXV.) " (XXVI.)

Ethyl 2-keto-4-carbethoxytetrahydropyrrolidene-5-cyanoacetate
(XXVII), being a monosubstituted derivative of ethyl )8-imino-
a-cyauoglutarate, might therefore be expected to react in the same
manner, yielding the lactam of carbethoxyglutazylacetic acid
(XXVIII) :

NH-C:C(C02Et)-CN NH-C:C(C02Et)

^^<CH2-CH.C0.,Et -^ ^^<CH2-C:C(0H)-N>^ ^^

(XXVII.) (XXVIII.)

This as a matter of fact it does, the reaction taking place not
only with concentrated sulphuric acid, but also on boiling for a
short time with dilute sulphuric or hydrochloric acids.

The lactam of carbethoxyglutazylacetic acid (XXVIII),
although insoluble in a cold solution of sodium carbonate, readily
dissolves on warming, yielding a solution of the sodium salt of
the amino-acid (XXIX), which, when mixed with sodium nitrite
solution and poured into hot acetic acid, evolves nitrogen and

COaEt

COaEt

NH./'^OH

C02Na-CH2L JN
OH

(XXIX.)

VOL.

XCV.

-> ^^\cH2' In •

OH

(XXX.)

5 a

1514 BEST AND THORPE: THE FORMATION AND

jiasscs into the lactone of trihydroxycarbetlioxypyridylacetic acid
(XXX).

From this substance, trihydroxypyridylacetic acid (XXXI) can
be i-eadily prcjoared by hydrolysis with sodium hydroxide.
Glutazylacetic acid (XXXII) can be prej^ared by the alkaline
hydrolysis of the lactam of carbethoxyglutazylacetic acid
(XXVIII) :

OH NH„

"■2

COgH-CH/ \ CO^H-CHj

HO' Job. hqi joh

N N

(XXXI.) (XXXII.)

Both glutazylacetic acid and ti'ihydroxypyridylacetic acid are
stable substances which do not readily pass into their anhydrides,
the behaviour of these compounds being in accordance with the
view previously expressed (Trans., 1904, 85, 1734), namely, that
those derivatives of glutazine or of trihydroxypyridine which have
both )8-positions substituted react as amino- or hydroxy-compounds,
whereas those which have only one /3-position substituted react
as tautomeric amino-imino- or keto-enolic compounds.

In this way, therefore, the constitution of the condensation
l^roduct of iodoacetonitrile and ethyl sodio-i8-imino-a-cyanoglutarate
has been definitely established. Further evidence is afforded, and,
moreover, more light is thrown on the nature of the isomeric
oxygen derivatives mentioned above by the study of a lower series
of derivatives of this substance.

This series starts with a compound, ethyl 2-iminotetrahydro-
pyrrolidene-5-cyanoacetate (XXXIII), which can be readily pre-
pared by the elimination of the carbethoxy-group from ethyl
2-imino-4-carbethoxytetrahydropyrrolidene-5-cyanoacetate (XIV) by
a method given in the experimental portion :

^jr.c^'^^-^'MG^yGO.Et NII-C:C(CN).CO,Et

(XIV.) (XXXIII.)

^ ^CH^-CH-GOgEt *

(XXXIV.)
It is a crystalline basic substance, which behaves both as an
amino- and as an imino-compound. It is, however, also possible
that in the formation of this substance the other carbethoxyl group
of the parent compound might have been affected, in which case
its formula would be represented by (XXXIV). That this is not
the case is shown by the fact that the corresponding dibasic acid,
which is always formed to a small extent in the reaction, and

REACTIONS OF IMINO-COMPOUNDS, PART X. 1515

can, moreover, be readily prepared from ethyl 2-keto-4-carbethoxy-
tetrahydropyrrolidene-5-cyanoacctate by careful treatment with
potassium hydroxide, and must therefore have either one or other
of the formula (XXXV) or (XXXVI) :

NH2-C:C(CN)-C02Et NH,-C:C(CN)-C02H

COaH-CM./CH-CO.H COJI-CHa'CH-COaEt

'(XXXV.) ' " (XXXVI.)

passes, when heated a few degrees above its melting point, into the
lactam of carbethoxyglutazylacetic acid (XXVII) :

CO H NH,-c:c(CO.,Et)^ co^^^"9=^'^^^^^'^^^r.OH

(.\XXV.) (XXVII.)

This reaction is analogous to the transformation of ethyl
hydrogen )8-imino-a-cyanoglutarate into ethyl glutazinecarboxylate,
which also takes place when the ethyl hydrogen salt is heated a
few degrees above its melting point (Trans., 1904, 85, 1729). It
is obvious that an acid of formula (XXXVI), in which the carboxyl
and nitrile groups arc attached to the same carbon atom, could
not undergo this transformation.

The behaviour of ethyl 2-iminotetrahydropyrrolidene-5-cyano-
acetate (XXXIII) is in every way analogous to that of the
corresponding carbethoxy-derivative, and there can be no question
that it is a tautomeric amino-imino-compound reacting in the two
forms :
^^„.^ .NH-C:C(CN)-C02Et , ,,^^ ^ .N C:C(CN)-COoEfc

There is, however, a greater difference in the stability of the
Mopyrrole form of the oxygen derivative, which incidentally fur-
nishes a proof that the structure of the imino-form as represented
above is the correct one. Thus, when ethyl 2-iminotetrahydro-
pyrrolidene-5-cyanoacetate (XXXII) is heated in acetic acid with
nitrous acid, there is formed an oxygen derivative melting at 145°,
which is insoluble in cold aqueous sodium carbonate. This is
therefore the isopyrrole form, ethyl 2-ketodihydrowopyrrolyl-
5-cyanoacetate (XXXVII) :
NH .r^^~V-^(^^)'^^2Et N=:C-CH(CN).C02Et

(XXXVII.)

This substance, when dissolved in alcohol and treated with
alcoholic potash, yields an insoluble potassium salt (XXXVIII),
which, when its solution in water is acidified, gives the isomeric
pyrrole derivative, ethyl 2-ketotetrahydropyrrolidene-5-cyanoacetate

5 G 2

1516 BEST AND THORPE: THE FORMATION AND

(XXXIX), which melts at 181° and dissolves in aqueous sodium
carbonate with effervescence :

^^^ .NK-C:C(CN)-COoEt NH-C:C(CN)-C02Eb

(xxxvni.) '(XXXIX.)

Now, when ethyl 2-iminotetrahydropyrrolidene-5-cyanoacetate
(XXXIII) is hydrolysed to the oxygen derivative by hot dilute
hydrochloric acid, that is, through the imino-form, the pyrrole
form of the ketone, melting at 181°, is obtained:

(XXXIII.) (XXXIX.)

This, therefore, is fairly definite evidence that the structure of
the imino-form is that given above. The isolation of the pyrrole
form in this reaction is rendered possible because this form is much
more stable than is the case in the corresponding carbethoxy-
derivative, as is shown by the fact that it is necessary to boil the
isopyrrole modification for some time with water before it is com-
pletely transformed into the derivative of «sopyrrole. The changes,
as in the former case, are represented thus :

N=C-CH(CN)-C02Et Through K salt. NH-C:C(CN)-CO.,Et

M. p. 145°, insol. in Na-jCOa. M. p. 181°, sol. in NaoCOs.

The /sopjTrole modification, when methylated through the silver
salt (XL), yields a methyl derivative (XLI), which, when boiled
with aqueous potassium hydroxide, is transformed into methyl-
amine and ethyl hydrogen a-cyano-/3-ketoadipate (XXIV) :

^NAg-C:C(CN)-C02Et ^NMe-C:C(CN)-C02Et

(XL.) (XLI.)"

^,_ ^ CO-CH(CN)-CO,Et

^^^^\cH,.6h, ' ' " + NllJIe.
(XXIV.)

The last-named compound is identical with the acid of this
formula, prepared in the manner mentioned on page 1513, only
in the present instance it is possible to follow the decomposition
more closely, for the following reasons :

It has already been mentioned that imino-compounds having
three negative groups attached to the carbon atoms adjacent to
the carbimino-group seem to react only as amino-compounds,
whereas those which have only two negative groups attached to
these carbon atoms react as tautomeric amino-imino-compounds.
Now. the open-chain compound which would be formed on breaking

^

REACTIONS OF IMIXO-COMPOUNDS. FART X. 1517

the pyrrole ring of ethyl 2-keto-4-carbethoxytetrahydropyrrolidenG-
5-cyanoacetate would be a compound of the first type :

^^^CHo-CHa'CO.Et ' "^ ^^^CHa"- CH-CO.Et " '

and should, like y-amino-acids, show little tendency to exist in the
open-chain form. The product of ring fission from ethyl 2-keto-
tetrahydropyrrolidene-5-cyanoacetate would, on the other hand,
be an imiuo-compound of the second type, and when once the ring
is broken the open-chain compound should be quite stable owing
to the production of the imino-form, or, rather, of that form
exhibiting amino-imino-tautomerism. This is, as a matter of fact,
the case, for whereas ethyl 2-kcto-4-carbethoxytetrahydro-
pyrrolidene-5-cyanoacetate is quite stable towards sodium carbonate
unless boiled for a long period of time, the ring of ethyl 2-keto-
tetrahydropyrrolidene-5-cyanoacetate (XXXIX) is at once broken
on merely warming with aqueous sodium carbonate, yielding ethyl
hydrogen )3-imino-a-cyanoadipate (XLII), and from this compound
ethyl hydrogen a-cyano-)3-ketoadipate (XXIV) can be prepared by
gently warming it with aqueous potassium hydroxide :
^^^NH-C:C(CN)-COoEt ^^^^ NH:C-CH(CN)-COoEb

(XXXIX.) (XLII.)

C0-CH(CN).C02Et

(xxiv.)

The degradation of the methyl derivative, ethyl 2-keto-l-methyl-
tetrahydropyrrolidene-5-cyanoacetate (XLI), can also be followed
in the same way. Thus, when warmed with aqueous sodium car-
bonate, it is converted into ethyl hydrogen o-cyano-)3-methylimino-
adipate (XLIII), from which ethyl hydrogen a-cyano-)8-ketoadipate
(XXIV) and methylamine are produced by the action of potassium
hydroxide :

^^^NMe-C:C(CN)-CO.,Eb ^ . ^ NMe:C-CH(CN)-C02Et

(XLI.) (XLIII.)

CO-CH(CN).CO,Et

(XXIV.)

A considerable temperature is necessary in order again to close
the pyrrole ring in these compounds, but both the above imino-
aud methylimino-derivatives are reconverted into the corresponding
derivatives of pyrrole on distillation under ordinary pressure. The
same behaviour is exhibited by ethyl hydrogen a-cyano-)8- ket o-

1518 BEST AND THORPE: THE FORMATION AND

adipate (XXIV), in which there is, of course, keto-enolic
tautomerism, for, although it exists as the keto-enolic acid under
ordinary conditions, yet it readily passes on distillation into the
corresponding lactone (XLIV), from which the ketonic acid is
regenerated by the action of alkalis :

m Tf. HO-C:C(CN).CO,Et ^0— C:0(CN)-CO,Et

(XXIV) : Euolic: form. (XLIV.)

From these experiments it is reasonable to conclude that only
those open-chain compounds which have an amino-group in the
y-position with respect to a nitrile group will yield imino-
derivatives of pyrrole on treatment with sodium ethoxide, and that
those substances which are tautomeric amino-imino-compounds will
not yield cyclic imino-derivatives under these conditions.

Experimental.

Ethyl ^-Imino-a-cyanogl'utarate,
COoEt-CH2-C(:NH)-CH('cN)-C02Et.

The preparation of this substance is described in a former paper
(Part I of this series, Trans., 1904, 85, 1736), but, as since that
time it has been found more convenient to employ a slightly
modified method for the preparation of it in quantity, and as,
moreover, the analysis given in the reference cited above referred
to another compound which had been prepared in a concurrent
research and had been included by an oversight, it is desirable
to give the improved method of preparation and the correct
analysis in the present instance. One hvmdred and thirteen
grams of ethyl cyanoacetate are mixed with a solution of
11 "5 grams of sodium dissolved in 122 grams of alcohol,
and the mixture heated on the water-bath until a
clear solution is obtained, that is to say, for about two
hours. Water is then added, and the solution, after being rendered
faintly acid by means of acetic acid, is distilled in a current of
steam until the distillate ceases to give an acid reaction. The
crude imino-ester, which solidifies in the flask on cooling, is then
collected and is sufficiently pure for further use, although for the
purpose of obtaining a dry specimen the product is best extracted
by means of ether and the ethereal extract dried and evaporated.
The following analyses are those which should have been given
in the former paper, in which the formula C]oIIj404Nf, should read

REACTIONS OF IMINO-COMPOUNDS. PART X. 1519

01923 gave 0-3739 COg and 01090 HoO. C = 5301; H = 6-3.
0-2041 „ 21-5 c.c. No at 15° and 770 mm. N = 12-5.

C10S14O4N2 requires C = 53-l; H = 6-2; N = 12-4 per cent.

Ethyl 2-Imino-^-carhethoxytetrahydi'0'pyrrolide7ie-^-cyanoacetate,

^•^^CH2-CH'C02Et

Tliis substance is prepared by the condensation of iodoacetonitrilc
with the sodium compound of ethyl /3-imino-a-cyanoglutai'ato.
Iodoacetonitrilc has been prepared by Henry {Bull. Soc. chim.,
1887, [ii], 47, 400) and by Scholl (Ber., 1896, 29, 2416) by the
action of potassium iodide on chloroacetonitrile, whilst an improved
method for its preparation has been recently given by v. Braun
(Ber., 1908, 41, 2134). For our purpose, it was found more con-
venient to use Scholl's method, mainly because ethyl chloroacetatc
was ready to hand. We are, however, quite in agreement with
v. Braun's observation that to employ the entire method of Scholl,
which involves the purification of the product by distillation in a
current of steam, is fatal to the production of anything like a good
yield, as the iodonitrile is for the most part hydrolysed to the
amide by this process. In the preparation of this substance by
Scholl's process, we therefore avoided the use of water as far as
possible, the alcoholic solution obtained after treating chloro-
acetonitrile with potassium iodide being evaporated as far as
possible to free it from alcohol and then extracted by ether. It
is necessary to wash the ethereal extract with water in order to
free it from the last traces of alcohol, but this process does not
affect the yield of the nitrile.

The condensation of iodoacetonitrilc and the sodium compound
of ethyl )8-imino-a-cyanogkitarate is best effected in the following
way. 2'4 Grams of sodium are dissolved in 50 grams of alcohol
and added to a solution of 23 grams of ethyl )8-imino-a-cyano-
glutarate dissolved in its own volume of alcohol. The alcoholic
solution containing the sodium compound of the imino-nitrile is
then cautiously mixed with 17 grams of iodoacetonitrilc, when a
vigorous reaction ensues, and it is necessary to keep the reacting
mixture cool by means of running water. Soon after the first
addition of iodoacetonitrilc, the condensation product begins to
separate as a yellow, crystalline precipitate, and when all has
been added, and the heat of the reaction has subsided, the separation
is almost complete. It is best, however, to keep the product for
half an hour, when water is added, and the imino-ester collected.
It is best purified by rubbing with cold absolute alcohol, in which

1520 BEST AND THOUrE: THE FORMATION AND

it is practically insoluble, and is then sufficiently pure for furtter
use. A specimen was prepared for analysis by recrystallisation
from a large quantity of alcohol, from which solvent it separates
in small, pale yellow needles, melting and decomposing at 205°:

0-1850 gave 0-3686 COo and 0-0967 HoO. C = 54-34; H = 5-81.

0-2008 „ 26-4 c.c. No "at 11° and 750""mm. N = 15-5.

C12H15O4N3 requires C = 54-3; H = 5-7; N = 15-8 per cent.

Ethyl 24minoA-carhethoxi/tetraliydro2njrrolidene-b-cyanoacetate
is sparingly soluble in all the usual organic solvents. It is insoluble
in alkali carbonate solutions even on boiling, but is slowly soluble in
aqueous alkali hydroxides. The alkaline solution thus formed
precipitates the original compound, melting at 205° on being
rendered acid with acetic acid, and when shaken in the air passes
into a deep blue compound, the nature of which has not as yet
been determined. The imino-nitrile dissolves at once in concen-
trated hydrochloric acid, evidently without undergoing any con-
siderable change, as the original base is, for the most part,
reprecipitated on adding water; a small quantity of the oxygen
derivative (see below) is, however, also formed at the same time
owing to the hydrolysis of the imino-form of the base, the quantity
being increased if the action of the acid is prolonged. The con-
centrated hydrochloric acid solution yields a crystalline precipitate
on standing, which is evidently the hydrochloride of the amino-
forra, since, on treatment with water, it is reconverted into the
base, decomposing at 205°. It was not found possible, however,
to contain a satisfactory analysis of this salt, owing to the fact
that it rapidly lost hydrogen chloride on drying, even in a
desiccator at the ordinary temperature.

Ethyl 2-Keto-A-ca7'bethoxydihydroisopyrrolyl-5-ci/anoacetate,
N = C-CH(CN)-C02Et
^CHa-CH-COgEt

This is the isopyrrole form of the ketone derived from the above
imino-nitrile, and can be prepared from it either by the action
of nitrous acid or by hydrolysis with dilute hydrochloric acid. As
the former method always yields a dark coloured product which
is difficult to purify, the action of hydrochloric acid is most to be
recommended for its preparation. The method found most suitable
was the following. Five grams of the imino-nitrile were dissolved
in sufficient concentrated hydrochloric acid, and the clear solution
poured into five times its volume of boiling water. A clear
solution was obtained, which, after the lapse of a few minutes,
because cloudy, owing to the separation of the ketone in the forip

REACTIONS OF IMINO-COMPOUNDS. PART X. 1521

of an oil. The hydrolysis was found to be complete after five
minutes, when the solution was cooled and the oil allowed to
crystallise. The compound separated from dilute alcohol in long,
colourless needles, melting at 109° :

0-1766 gave 0-3524 COo and 00793 IIoO. C- 54-42; n = 4-99.
0-2026 „ 18-6 c.c. No "at 17° and 76o"mm. N = 10-6.

CJ2H14O5N2 requires C = 541; H = 5-3; N = 10-5 per cent.

. The production of the ketone by this process is almost quantita-
tive, and no trace of other products could be detected. Ethyl
2-keto-^-carhethoxydihydro'pyr7-olyl-b-cyanoacetate is insoluble in
ice-cold aqueous sodium carbonate, but dissolves on warming,
forming the sodium salt of the pyrrole modification (see below).
The alkaline solution can be boiled for a considerable time without
effecting any change, ultimately, however, hydrolysis ensues, and
open-chain degradation products are formed. It is instantly soluble
in aqueous alkali hydroxides, forming a solution which slowly
oxidises to a blue compound on shaking with air, and is
characterised by giving a substance closely resembling indigo in
appearance when it is boiled for a short time with methyl sulphate.
This compound, as well as that which is formed from it on
oxidation, are under investigation. The keto-ester does not lend
itself to the formation of derivatives, and is unacted on by semi-
carbazide and by aniline. It may also be prepared from the
imino-compound by the action of nitrous acid, but the product
formed in this manner is always dark coloured and difficult to
purify; the formation in this way shows, however, that the imino-
compound reacts in the amino-form, since the reaction is carried
out in acetic acid solution, which does not hydrolyse the imino-
form. The formation of derivatives of glutazine from the keto-
ester by the action of dilute sulphuric acid is described on page
1526.

Ethyl 2-KetoA-carhetho3ytetrahydro'pyrrolidene-b-cyanoacetatey
NH-C:C(CN).C02Et
^CHg-CH-CO.^Et

The above pyrrole form of the ketone can be prepared by gently
warming 3 grams of the isopyrrole form with aqueous sodium
carbonate solution until all has passed into solution, and then,
after cooling the solution with ice, cautiovisly acidifying it with
hydrochloric acid. A small quantity of the isopyrrole form first
separates as an oil, which can be removed by filtration, and the
filtrate then gives a white, crystalline precipitate on scratching
the sides of the containing vessel. The compound prepared in this

1522 BEST AND THORPE: THE FORMATION AND

way melts at 129°, and dissolves in aqueous sodium carbonate
solution with effervescence. It cannot be recrystallised, since at a
comparatively low temperature the isopyrrole modification is
regenerated. Its purity was tested by again dissolving the product,
melting at 129°, in sodium carbonate solution, and reprecipitating
with hydrochloric acid in the manner described above, when the
melting point of the acid was found to be unaltered :

01818 gave 03592 COo and 0-0832 HgO. C = 53-88; H = 5-08.
CjoHj^OjNa requires 0 = 54*1; H = 5-3 per cent.

The pyrrole form appears to be more soluble in water than the
rsopyrrole form, but is much less soluble in alcohol. The acid
gave the following figures on titration: 0-2962 requires 11*4 c.c.
of i\'/10-sodium hydroxide: a monobasic acid, C12HJ4O5N2, requires
11-5 c.c.

The silver salt, Ci2Hi305N2Ag, is a gelatinous substance, which
can, however, be dried at 80° without undergoing change:

0-2276 gave 0-0659 Ag. Ag = 28-95.

CjoHjgOjNoAg requires Ag = 28-95 per cent.

Conversion of Ethyl l-KetoA-carhethoxypyrrolidene-^-cyano-
acetate into Ethyl %KetoA-carhethoxydiliydro\s,o'pyrrolyl-^-cyano-
acetate. — This conversion is completely effected when the first-
named compound is melted. It can, however, be conveniently
brought about by dissolving the pyrrole form in hot alcohol, when
the Z6^opyrrole modification separates from the solution on cooling.
For the purpose of converting larger quantities, the following
method yields good results. Ten grams of the pyrrole form are
mixed with 100 c.c. of boiling water, and the clear solution allowed
to cool. An oil separates, which quickly sets to a viscid syrup, and
can be removed by the aid of a glass rod, leaving a solution
which can be filtered if necessary, and deposits a small quantity
of unchanged pyrrole form on standing. The viscid syrup collected
on the glass rod rapidly solidifies on rubbing with water, and
when recrystallised from dilute alcohol yields the characteristic
needles of the zsopyrrole modification, melting at 109°. It is
possible, by boiling the aqueous solution of the pyrrole form for
a longer period of time, to convert it completely into the zsopyrrole
modification.

REACTIONS OF IMINO-COMPOUNDS. PART X. 1523

The Products of Alkaline Hydrolysis of Ethyl 2-KetoA-carhethoxy-
dihydroiso'pyrrohjl-b-cyanoacetate.

(1) Ethyl Dihydrogen ^-Iniino-a-cyanohutane-ayZ-tricarhoxylatey
C02H-CH2-CH(COoH)-C(:NH)-CH(CN)'C02Et.

This compound occurs as an intermediate product in the
hydrolysis of the isopyrrole derivative by means of aqueous sodium
carbonate, which leads ultimately to the formation of ethyl
hydrogen a-cyano-/8-ketoadipatc (see below), and can be isolated
by extracting the mother liquors from this substance by means
of ether. It may be, however, prepared in larger qiiantity by the
hydrolysis of the imino-compound by the following process. Ten
grams of ethyl 2-imino-4-carbethoxytetrahydroxypyrrolidene-
5-cyanoacetate are mixed with 50 c.c. of boiling water and 10 c.c.
of 50 per cent, aqueous potassium hydroxide added. The clear
solution is then shaken until a test portion no longer gives a precipi-
tate with hydrochloric acid, which occurs after about five minutes,
when the solution is acidified and extracted thoroughly with ether.
When purified by recrystallisation from dilute hydrochloric acid
(1 : 1), the ethyl hydrogen salt is obtained in small, colourless
prisms, melting at 160°, evolving carbon dioxide, and almost
immediately resolidifying to a yellow solid (the lactam of
carbethoxyglutazylacetic acid : see page 1526) :

0-1830 gave 0-3134 COg and 0-0793 HgO. C = 46-70; n = 4-81.
CiqHj.OcNo requires C = 46-9; H = 4-7 per cent.

The acid is fairly readily soluble in cold water, and when warmed
with aqueous potassium hydroxide evolves ammonia and passes into
ethyl hydrogen o-cyano-i3-ketoadipate (see below). The silver salt,
CjoHnjOgNoAgo, is precipitated as a white, crystalline solid on
adding the calculated quantity of a solution of silver nitrate to a
neutral solution of the ammonium salt of the acid :

0-2109 gave 0-0968 Ag. Ag = 45-89.

CioHjoOgNgAgg requires Ag = 45-95 per cent.

(2) Ethyl Hydrogen a-Cyano-^-ketoadipate,
C02H-CH2-CH2-CO-CH(CN)-C02Et.

This ketone is the final product of the action of boiling sodium
carbonate solution on ethyl 2-keto-4-carbethoxytetrahydro-
pyrrolidene-5-cyanoacetate or its isomeride, and can be prepared
in quantity by the following process. Ten grams of the pyrrole
or isopyrrole derivative are mixed with 100 c.c. of a 10 per cent,
solution of sodium carbonate, and boiled until the odour of

1524 BEST AND THORPE: THE FORMATION AND

ammonia ceases to be apparent, an operation which takes about
six hours. The clear solution is then acidified with hydrochloric
acid, causing the separation of an oil which rapidly solidifies. It
can be purified by recrystallisation from dilute alcohol, when it
yields colourless needles melting at 104°, and evolving gas at 140° :

0-1957 gave 0-3626 COo and 0-0933 H2O. C = 50-53; H = 5-29.

0-2660 „ 15-4 c.c. Ngat 17° and 762 mm. N = 6-73.

C9H11O5N requires" C = 50-7; H = 5-l; N = 6-6 per cent.

Ethyl hydrogen a-cyano-fi-ketoadipate is readily soluble in all
the usual organic solvents excepting light petroleum. It gives in
alcoholic solution a deep red colour with ferric chloride. It was
proved to be a dibasic acid by titration with i\^/10-sodium
carbonate.

The silver salt, CgHgOjNAg,, separates as a white, crystalline
solid on adding the calculated quantity of a solution of silver
nitrate is a neutral solution of the ammonium salt of the acid :

0-2463 gave 0-1246 Ag. Ag = 50-58.

CgHgOjNAgg requires Ag = 50-58 per cent.

Lactone of Ethyl Hydrogen a-Cyano-^-hydroxy-a^-hydromuconate,
CH2-CH2-C:C(CN)-C02Et
CO O

This substance can be prepared by the distillation of ethyl
hydrogen a-cyano-j8-ketoadipate. The following conditions were
employed. Pive grams of the ketone were placed in a small dis-
tillation flask fitted to the vacuum distillation apparatus, and
heated under diminished pressure until all water had been evolved,
when the residue was distilled, and the fraction boiling at
140 — 150°/30 mm. collected. The colourless oil obtained in this
way partly solidified on keeping, and the mixture was therefore
treated with sodium carbonate solution, in which the solid dissolved,
leaving the oil unchanged. The oil was then separated by means
of ether, the ethereal solution leaving an oil on evaporation which
boiled at 142 — 145°/ 30 mm., yielding a clear, fairly mobile liquid
which could not be crystallised :

0-2145 gave 13-8 c.c. Ng at 20° and 751 mm. N = 7-3.
C9H9O4N requires N = 7-2 per cent.

The lactone is insoluble in cold water and only slowly dissolves
on boiling, separating for the most part unchanged from the
solution on cooling. It can be distilled in a current of steam
without undergoing appreciable hydrolysis, but is quickly hydro-
lysed by hot aqueous alkali hydroxide, yielding a clear solution,
from which ethyl hydrogen a-cyano-;8-ketoadipate separates on

I

REACTIONS OF IMINO-COMPOUNDS. PART X. 1525

acidifying. Tlie sodium carbonate solution obtained in the puri-
fication of the lactone yields a solid acid on acidifying, which
separates from benzene in colourless plates melting at 121°. It
gives no colour with ferric chloride, and does not decolorise
permanganate in sodium hydrogen carbonate solution. The quan-
tity obtained was too small for further investigation.

(3) Succinic aiid Malonic Acids.

The ultimate products obtained by the complete hydrolysis of
ethyl 2-keto-4-carbethoxydihydro/sopyrrolyl-5-cyanoacetate with
aqueous potassium hydroxide are succinic and malonic acids. The
experimental conditions employed were as follows. Five grams
of the ?sopyrrole derivative were suspended in water and mixed
with aqueous potassium hydroxide containing one and a-half times
the calculated quantity of the alkali. The solution was then boiled
until ammonia ceased to be evolved, when hydrochloric acid was
added, and the clear solution extracted on the shaking machine
with ether. The ethereal solution on evaporation left a solid
residue, which, when recrystallised from water, yielded the
characteristic crystals of succinic acid melting at 185°:

01810 gave 0-2706 CO, and 0-0844 HgO. C = 40-77; H = 5-18.
C4HQO4 requires C = 40-7; H = 5"l per cent.

The aqueous residue from the ether extraction was then
evaporated to dryness on the water-bath, and the dry residue
extracted in a Soxhlet apparatus with ether. The ethereal extract
on evaporation yielded a solid residue containing a considerable
quantity of succinic acid, which had not been extracted in the
previous extraction. The separation was effected by rubbing the
mixed acids with dry ether, in which succinic acid is practically
insoluble, but in which malonic acid dissolves readily. By repeating
the process, it was ultimately possible to isolate malonic acid,
melting at 132° :

0-1938 gave 0-2439 COo and 00675 H2O. C = 34-31 ; H = 3-87.
C3H4O4 requires 0 = 34 6; H = 3'8 per cent.

1526 REST AND THORPE : THE FORMATION AND

The Frodncis of Acid Hi/droli/sis of Ethyl 2-Keto-A-carhethoxi/-
dihydroisojiyrrolyl-b-cyanoacetate.

(1) The Lactam of CarhetJioxyglutazylacetic Acid,
NH-CO

ho' Ioh •

\/

N

This substauce may be prepared either by the action of dilute
sulphuric acid on the isopyrrole derivative, or by heating ethyl
dihydrogen ;8-imino-a-cyanobutane-o-y5-tricarboxylate above its
melting point.

(i) From the i^opyrrole derivative. — This method, which is the
most convenient for the preparation of large quantities of the
lactam, is carried out as follows. Ten grams are boiled with a
10 per cent, solution of sulphuric acid until the oil which floats at
the top of the hot acid has completely solidified, when the solid
is collected and separated from any vmchanged isopyrrole derivative
by washing with alcohol.

(ii) From the dihydrogen salt. — Five grams are heated in a test-
tube placed in a bath of sulphuric acid at 155° for ten minutes.
Some carbon dioxide is evolved during the process of heating,
and the solid ultimately becomes transformed into a yellow, semi-
solid mass. It is then cooled and mixed with dilute sodium
carbonate solution, which causes the oily portion to dissolve, leaving
a yellow solid ; this can be obtained colourless by washing with
alcohol. The sodium carbonate solution, on acidifying, yields an
oil, which becomes solid on scratching, and consists of ethyl
hydrogen )3-imino-a-cyanoadipate, ^

C02H-CH2-CH2-C(:NH)-CH(CN)-C02Et, '

melting at 131° (see page 1534), which is evidently formed
by the elimination of the carboxyl group from the dihydrogen
salt.

When prepared by either of these methods, the lactam is an
insoluble substance, which separates from a large quantity of hot
water as small needles, decomposing at a high temperature without
melting :

0-1863 gave 0*3441 COo and 00705 HgO. C- 50-37; H = 4-20.
0-2010 „ 20-1 c.c. Noat 9° and 757*'mm. N = ll-9.

CioHioOjNs requires C = 50-4; H-4-2; N^ll'S per cent.

Tiie lactam is insoluble in cold sodium carbonate solution, and

REACTIONS OF IMINO-COMPOUNDS. PART X. 1527

its aqueous solution gives a purple coloration with ferric chloride,
which changes to green after boiling for a few minutes.

(2) Carhethoxyglutazylacetic Acid,
Nil,

Hoi Job. " '

N

The lactam described above dissolves when boiled with sodium
carbonate solution, and the above acid separates when the cold
alkaline solution is acidified. The compound does not possess a
definite melting point, and cannot be recrystallised, since when
boiled with water it is reconverted into the lactam, which separates
from the solution on cooling :

0-2012 gave 18-2 c.c. N2 at 10° and 758 mm. N = 10-8.
CjoHjoOgNg requires N = 10"9 per cent.

The acid is soluble in sodium carbonate solution, and behaves
towards ferric chloride in the same manner as the lactam,

(3) The Lactone of Trihydroxycarhethoxypyridylacetic Acid,

0-CO

N

This compound can be prepared by the action of nitrous acid
on carhethoxyglutazylacetic acid in the following way. The
glutazine derivative is dissolved in dilute aqueous potassium
hydroxide, and, after having been mixed with a solution containing
excess of sodium nitrite, is poured into a hot dilute solution con-
taining excess of acetic acid. The mixture becomes at once desp
green, and the pyridine derivative slowly separates as a crystalline
powder. It was purified by recrystallisation from water, in which
it is sparingly soluble, and obtained in microscopic needles, which
decompose at a high temperatvire without melting :

0-1913 gave 0-3513 CO2 and 0-0671 H.O. C = 50-08; H = 3-89.
CjoHgOcN requires C = 50-2; H = 3-8 per cent.

The lactone is insoluble in sodium carbonate solution, and gives
in aqueous solution a red coloration with ferric chloride, which
disappears on warming. The corresponding acid could not be
isolated, for, although the lactone dissolved when boiled with
sodium carbonate solution, evidently undergoing transformation

1528 BEST AND THORPE: THE FORMATION AND

into the sodium salt of the acid, yet on acidifying the solution
a substance separated which was insoluble in sodium carbonate
solution, and was evidently therefore the lactone.

(4) Glutazylacetic Acid,
NH2

HOl JOH"

This acid can be prepared by the action of aqueous potassium
hydroxide on the lactam of carbethoxyglutazylacetic acid. The
lactam is mixed with 30 per cent, aqueous potassium hydroxide,
and the solution boiled in an open vessel until the odour of
ammonia begins to be apparent. Water is then added, and the
solution acidified with hydrochloric acid. Providing the solution
is sufficiently concentrated, the acid then slowly separates as a
crystalline precipitate ; this can be purified by recrystallisation
from a little water, from which it separates in small, glistening
plates, usually pale yellow in colour. The acid melts and blackens
at about 270° when rapidly heated, but when slowly heated begins
to char much below this temperature :

0-2121 gave 28-6 c.c. N2 at 17° and 748 mm. N = 15-4.
C7H8O4N2 requires N = 15'2 per cent.

Glutazylacetic acid is readily soluble in hot water. It gives with
ferric chloride in aqueous solution a red coloration, which changes
to green on boiling. The acid does not appear to pass readily into
the lactam, for, although it evidently loses water on heating, yet at
the high temperature necessary much charring takes place, and no
definite product covild be isolated.

(5) Trihydroxypyridylacetic Acid,
OH
/^iCH^-COg-H

ho' Ioh

N

This acid may be prepared either by the hydrolysis of tri-
hydroxycarbethoxypyridylacetic acid with potassium hydroxide, or
by the action of dilute sulphuric acid on glutazylacetic acid.

(1) From trihydroxycarhethoxypyridylacetic acid. — Three grams
of the acid are heated in an open vessel with 5 c.c. of 30 per
cent, aqueous potassium hydroxide until a test portion gives no
precipitate on acidifying. The solution is then acidified with

I

REACTIONS OF IMINO-COMPOUNDS. PART X. 1529

liydrochloric acid and kept, wlion, provided tlic solution is suffi-
ciently concentrated, the pyridine acid slowly separates as a
crystalline powder.

(2) From ffliitazi/hirefic acid. — Three grams of the acid are
boiled with 10 per cent, sulphuric acid for two hours. The solution
is then rendered alkaline with ammonia, acidified with hydrochloric
acid, and evaporated on the water-bath to a small bulk. The
pyridine derivative separates on keeping the concentrated solution.

Trill yd ro.ryptj rid ylacetic acid separates from a small amount of
water in small prisms, usually yellow in colour. It does not possess
a definite melting point, but when heated begins to blacken at
about 220° :

0-2182 gave 144 c.c. No at 18° and 763 mm. N = 7-7.
C;H703N requires N = 7'6 per cent.

The acid is readily soluble in water, and gives a red coloration
with ferric chloride, which disappears on warming. As in the
case of glutazylacetic acid, the corresponding anhydride could not
be isolated owing to the high temperature required for its formation.

Ethyl 2-Ketu-4.-carhelhoi y-Y-methyltetrahydrupyrrolidene-
b-cyanoacetate,
,NMe-C:C(CN)-C02Et
^CH-CH-COoEt ' •

co<;^

The methylation of ethyl 2-keto-4-carbethoxytetrahydro-
pyrrolidene-5-cyanoacetate cannot be readily effected. The sub-
stance is a strong acid, but acid etherifying agents, such as alcohol
and sulphuric acid; cannot be used, since at the necessary tem-
perature the compound rearranges to the /sopyrrole form, which
docs not alkylate. Moreover, alkaline alkylating agents, such as
sodium ethoxide and an alkyl iodide, do not lead to good results, as
the sodium salt of the pyrrole form is not readily acted on by
alkyl iodides. The only satisfactory method is to treat the silver
salt suspended in dry benzene with methyl iodide in the following
manner. Five grams of the silver salt, prepared in the way
described on page 1522, were carefully dried at 80°, ground to a
fine powder, and transferred to a Gcissler flask, in which it was
mixed with 50 c.c. of dry benzene. Excess of methyl iodide was
then added, and the flask heated on the water-bath. The reaction
Icommenced on warming, and was complete after heating for two
Ihours, when the benzene sokition was filtered and evaporated. The
l)ily residue solidified on cooling, and was purified by recrystallisation
;rom alcohol, being obtained in long, colourless needles, melting
lit 84°:

VOL. XCV. 5 H

1530 BEST AND THOKPE: THE FORMATION AND

01859 gave OSldl COo and 00950 H.O. C = 55-62; H = 5-67.
CjgHjpO^No requires C = 55'7; H = 5"7 per cent.

The methyl derivative is insoluble in cold aqueous potassium
hydroxide. A small quantity of the same methy] derivative was
obtained on alkylating the pyrrole derivative by means of sodium
ethoxide and methyl iodide.

Hydrolysis of Ethyl 'l-KetoA-carhethoxy-l-methyltctrahydro-
j)yrrolicle7ie-5-ryanoacefatc. — This hydrolysis is best effected by
means of aqueous potassium hydroxide under conditions which
allow the methylamine formed to be collected. Five grams were
l^laced in a flask connected with a condenser and mixed with an
aqueous solution containing the calculated quantity of potassium
hydroxide necessary to hydrolyse it to the dipotassium salt of ethyl
hydrogen a-cyano-^S-ketoadijDate,

002K-CH2-CH2-CO-CK(CN)-C02Et,
that is to say, 4 grams. The flask was then heated on the sand-
bath, and the distillate collected in dilute hydrochloric acid, care
being taken to prevent loss of methylamine by causing the con-
denser tube to dip under the surface of the acid. The heating
was continued until all oil had passed into solution, when steam
was passed through the flask in order to remove the last traces of
the base. The residue was then acidified, yielding an oil which
solidified on standing. It was collected and recrystallised from
dilute alcohol, giving colourless needles, melting at 104°, which
analysis showed to consist of ethyl hydrogen a-cyano-^-ketoadipate :

0-1805 gave 0-3347 COo and 00809 HgO. C = 50-52; H = 4-98.
C9HJ1O5N requires C = 50-7; H^O'l per cent.

The hydrochloric acid distillate was then evaporated to a small
bulk, and mixed with excess of platinic chloride solution and an
equal volume of alcohol. The golden-yellow plates which then
separated were collected, dried, and analysed :

0-2316 gave 00954 Pt. Pt = 41-19.

(NTIoMe,HCl)2PtCl4 requires Pt -41-34 per cent.

The base was therefore methylamine.

Ethyl 2-IininotetraJiydroiiyrrolidenc-b-cyanoacctale,

The carbcthoxy-group can be readily eliminated from ethyl
J-imino-4-carbethoxytetrahydropyrrolidene-5-cyanoacetate without
affecting the imino-group by the following process. Ten grams
of the imino-ester, ground to a fine powder, are suspended in
100 c.c. of water at 80° and mixed with 20 c.c. of 50 per cent.

\

itEACTioNs OF iMfyo-roMi'ouxns. TAirr x. lo'U

aqueous potassium hydroxide. A clear snlulion if; at once obtained,
wliich is kept for thirty seconds and is tlien quickly cooled. It
is advisable to avoid shaking the llask during this period, as the
alkaline solution rapidly oxidises to a blue compound when in
contact with air. The cooled solution is then acidified with acetic
acid, and a quantity of unaltered imino-compound which then
separates is collected. It is possible so to arrange the time of
the reaction as to cause the whole of the carbethoxy-derivative to
be hydrolysed by the alkali, in which circumstances none is, of
course, recovered on acidifying with acetic acid. This point is,
however, difficult to determine, and as other products are formed
by the further action of the alkali, it is best to use the above
conditions, which enable the reaction to be stopped before the
whole of the cai'bethoxy-derivative is hydrolysed. The recovered
ester can, of course, be used again. The filtrate from the unaltered
imino-compound which contains the carboxylic acid in solution is
then boiled, whereby carbon dioxide is eliminated, and ethyl
2-iminotetrahydropyrrolidene-5-cyanoacetate precipitated. When
recrystallised from a large volume of alcohol, it is obtained in
microscopic needles, usually pale yellow in colour, which melt and
decompose at 256° :

0-1610 gave 0-3319 CO. and 00802 HoO. C = 56-22; H = 5-53.

0-2006 „ 37-2 c.c. No "at 15° and 762^ mm. N = 21-77.
C9H11O2N3 requires C = 55-9; H = 5-7; N = 21-7 per cent.

Ethyl 2-iminotetrahydro'pyrrolidenc-^-cyanoacetate is sparingly
soluble in all the usual organic solvents, but can be recrystallised
from a large volume of hot water, in which it is more soluble than
the corresponding carbethoxy-derivative. It is quite insoluble in
alkali carbonates or hydroxides, but in the case of the last-named
reagents it dissolves on warming, yielding products of fission of
the pyrrolidine ring. It is obtained by the process given above
in yields of about 75 per cent, of the theoretical, although this
is considerably decreased if the action of the alkali is prolonged,
for by this means the pyrrolidine ring is broken and ethyl
hydrogen i8-imino-a-cyanoadipate,

COoH'CH2'CH2-C(:NH)-CH(CN)-C02Et
(see page 1534), is formed. The imino-compound is soluble in dilute
hydrochloric acid, but a crystalline hydrochloride could not be
isolated.

1532 BEST AND THORPE: THE FORMATION AND

Ethyl 2-Kctntetra]ii/<lrn2jyrroIi(l('np-T)-ryavnarefate,
MH-C:C(CN)-CO.,Et

The above pyrrole form of the ketone may be prepared from the
imino-compoiind by the action of dilute hydrochloric acid. Five
grams of the imino-compound are finely ground and suspended in
30 o.c of warm water. Five c.c. of concentrated hydrochloric acid
are now added, and the clear solution kept, when long needles of
the pyrrole form separate. It is best purified by rapid re-
crystallisation from alcohol, for, although a certain quantity is
converted into the ?.5opyrrole modification by this means, yet owing
to the fact that the pyrrole form is much less soluble in alcohol
than the j'sopyrrole form the crystals which separate first are pure
ethyl 2-ketotetrahydro2JyrroUdene-h-cyanoacetate. The compound
forms rhombic prisms, melting at 181°:

0-1822 gave 0-3716 CO, and 00838 HoO. C = 55-62; H = 5-ll.
0-2120 „ 26-4 c.c. Ng at 17-5° and 748 mm. N = 14-2.

CyHjoOgNo requires C = 55-7; H = 5-l; N = 14-4 per cent.
The ethyl salt is characterised by forming alkali salts, which are
insoluble in excess of the alkali. Thus, when treated with a con-
centrated solution of sodium carbonate, it dissolves, but almost
directly deposits the sodiuin salt as a white, crystalline precipitate.
In the same way, the potassium salt separates when the acid is
dissolved in concentrated aqueous potassium hydroxide and allowed
to stand.

The potassium salt, CgHgOgNoK, is best prepared by dissolving
the acid in alcohol and adding an alcoholic solution containing the
requisite quantity of potassium hydroxide, when it separates as
a sandy powder. It can be conveniently purified by washing with
hot alcohol, in which it is very sparingly soluble, but can also be
recrystallised from a small quantity of water, from which solvent
it separates in small, colourless prisms :
0-2278 gave 0-0844 K2SO4. K- 16-61.

C9H8O3N2K requires K = 16-88 per cent.
The salt is readily soluble in cold water, forming a solution
which is alkaline to litmus.

The silver salt, CgHgOgNoAg, is difficult to prepare in the usual
manner through tE'e ammonium salt, but is readily formed when
an aqueous solution of the potassium salt is mixed with a solution
containing the calculated quantity of silver nitrate. It is a
gelatinous substance, which can be dried to a fine, apparently
amorphous powder by heating it at 80° :

REACTIONS OF IMINO-OOM POUNDS. PART X. 1588

0-2331 gave 00838 Ag. Ag-35-9r).

CrjIIsO.jNoAg requires Ag = 35'88 per cent.
The silver salt is slowly affected on exposure to light.

Ethyl 1-K e t nd iliyd ro\?,0'pyrrnl ijl -V)-ni(tvnnrei of p ,

The /sopyrrole form of the ketone can ])e prepared either by
the action of nitrons acid on the imino-componnd, or by the action
of boiling dilute hydrochloric acid. In tlie first case, the pure
Mopyrrole derivative is formed, in the second a mixture of the
two forms.

By the action of nitrous acid. — Ten grams of the imino-
compound are ground to a fine powder and suspended in 20 c.c. of
glacial acetic acid, the mixture being added to a boiling solution
containing 5 grams of sodium nitrite in 100 c.c. of water. A
considerable quantity of gas is evolved, and a clear solution, which
is usually red in colour, is obtained after boiling for a few minutes.
As soon as this point is reached, the solution is cooled, and the
?'.?opyrrole derivative which then separates is collected and purified'
by recrystallisation from either water or alcohol. It forms colour-
less needles, melting at 145°.

By the action of hot dilute hydrochloric acid. — The imino-
compound is suspended in boiling water and concentrated hydro-
chloric acid added, the solution being raised to boiling for a few
minutes. On cooling, crystals separate, which, when collected and
treated with dilute sodium carbonate solution, leave an insoluble
residue consisting of the /sopyrrole form, melting at 145°. The
sodivxm carbonate solution, on acidification, yields the pyrrole
form, melting at 181°. The proportion of the two forms present
in this product depends entirely on the length of time the hydro-
chloric acid solution is heated. It is possible, by prolonging the
heating sufficiently, to obtain only the /sopyrrole form, melting
at 145°:

0-1778 gave 0-3630 COo and 00818 H.O. C = 55-68; H=5-ll.

0-2091 „ 27-1 c.c. N.2'at 165° and 738 mm. 1^=14-6.
C9H10O3N2 requires 0 = 55 7; H=;5-l; N = 14-4 per cent.

The fsopyrrole derivative is insoluble in sodium carbonate
solution, but dissolves on warming, being for the most part
transformed, with fission of the tsopyrrole ring, into the sodium
salt of ethyl hvdrogen jS-imino-a-cyanoadipate (see page 1534). It
is soluble in cold aqueous potassium hydroxide, and, providing
the alkali is strong, the potassium salt of the pyrrole form separates

1534 BEST AND THORPE : TriE FORMATIOK AND

on standing. The alkaline solution shows no tendency to oxidise
in the air, and the action of methyl sulphate does not lead to the
production of a coloured substance.

Transformation of the 'pyrrole form into the isojn/rrole form,
and vice versa. — The pyrrole form is comparatively stable, and
it is possible to sublime it, when dry, at a temperature of 180°
Avithout causing it to pass into the ?'.'?«pyrrole modification. As
already mentioned, it can be recrystallised from alcohol without
undergoing change, although prolonged boiling with this solvent
slowly converts it into the /.^'opyrrole derivative. Hot water acts
more quickly, and boiling for ten minutes is usually sufficient to
convert one gram completely into the /.5opyrrole form. The
reverse change is best effected through the potassium salt in the
following way. One gram of the isopyrrole modification is dissolved
in alcohol, and the requisite quantity of potassium hydroxide
dissolved in alcohol added. The potassium salt of the pyrrole
form separates, which, when dissolved in water and acidified,
yields the pure pyrrole modification in glistening laminae, melting
at 181°. The following analysis was made in order to establish
its identity :

0-1797 gave 0-3662 COo and 00834 HgO. 0 = 55-58; H = 5-14.
CgHj^OgNo requires C = 55'7; H = 5-l per cent.

Ethyl Hydrogen ^-Imino-a-cyanoadi'pate,
00.3H-0Ho-CHo-0(:Nn)-0H(CN)-00oEt.

This compound occurs in a number of reactions involving the
hydrolysis of both ethyl 2-imino-4-carbethoxytetrahydropyrrolidene-
5-cyanoacetate and ethyl 2-iminotetrahydropyrrolidene-5-cyano-
acetate, but can be prepared in qviantitative yield by warming
ethyl 2-ketodihydro?sopyrrolyl-5-cyanoacetate with sodium car-
bonate solution. The first action of the alkali is to form the
sodium salt of the pyrrole modification, but if the solution is
boiled for a few minutes fission of the pyrrole ring ensues v/ith the
production of the above compound. The operation is performed
as follows. Two grams of the isopyrrole derivative or its isomeride
are boiled with 20 c.c. of a 10 per cent, solution of sodium
carbonate for five minutes, and the clear solution, after being
cooled, is acidified with hydrochloric acid. A crystalline pre-
cipitate separates, which, when recrystallised from hot water, yields
feathery needles, melting at 131° and evolving gas at 160°:

0-1786 gave 03331 OOg and 0-0906 HgO. 0 = 5086 ; H - 563.
0-2040 „ 23 c.c. Ng at 12-5° and 747 mm. N = 13-37.
O9H12O4N2 requires 0 = 50-9; H = 5-7; N = 13-2 per cent,

REACTIONS OF IMINO-COMPOUNDS. PART X. 1535

The silrcr salt, CgHjjO^NoAg. separates as a white, bulky pre-
cipitate when the calculated quantity of an aqueous solution of
silver nitrate is added to a neutral solution of the ammonium salt
of the acid. It darkens rapidly on exposure to light :

0-2173 gave 00735 Ag. Ag = 33-82.

CjjHjjO^I^oAg requires Ag = 3385 per cent.

Ethyl hydrogen )3-imino-a-cyanoadipate is stable towards hot
sodium carbonate solution, and can be boiled for some time with
this reagent without undergoing change, but, when boiled for a
few minutes with aqueous potassium hydroxide, it evolves ammonia
and passes into ethyl hydrogen a-cyano-)3-ketoadipatc (see page
1524). The operation is effected by boiling 1 gram with 5 c.c. of
a 20 per cent, solution of potassium hydroxide for one minute and
acidifying the solution, when an oil separates which slowly solidifies.
On recrystallisation from dilute alcohol, it yields the characteristic
needles of ethyl hydrogen a-cyano-;8-ketoadipate, melting at 104°,
and giving a red coloration with ferric chloride :

0-2454 gave 14-2 c.c. Ng at 18° and 762 mm. N = 6-7.
C9H51O5N requires N = 6-6 per cent.

Ethyl hydrogen /3-imino-a-cyanoadipate is slowly hydrolysed by
mineral acids to the corresponding ketone, and is partly transformed
into the same compound on treatment with nitrous acid. When
distilled rapidly, in small quantities, under the ordinary pressure,
it loses water and is reconverted into ethyl 2-ketodihydro^6■opyrrolyl-
5-cyanoacetate. The following analysis was made of the product
obtained in this way and recrystallised from water. It melted
at 145°:

0-2300 gave 29-8 c.c. Nc, at 17° and 740 mm. N-14-6.
C9H10O3N2 requires N = 14'4 per cent.

Ethyl "l-K eto-1-methyltetrahydro'pyrrolidene-b-cyanoacetate ,
NMe-C:C(CN)-C02Et

The methylation of ethyl 2-ketotetrahydropyrrolidcnc-5-cyauo-
acetate presented some difficulties. In the first place, it was not
found possible to bring about interaction between the potassium
salt and methyl iodide, for even after prolonged boiling in
alcoholic solution the potassium salt remained unacted on. Again,
when the potassium salt was suspended in methyl alcohol and
treated with methyl sulphate, although interaction ensued and
potassium sulphate separated, the product was found to consist of
uuclumgcd ethyl 2-ketotetrahydropyrrolidenc-5-cyanoacctatL', and
no trace of a methyl derivative could be isolated. This curious

1536 BEST AND THORPE: THE FORMATION AND

leactiou is evidently caused by the ionisation of the potassium
salt in solution. Attempts made to prepare the methyl derivative
by the ordinary process of alcohol and sulphuric acid etherification
led to no result, since at the necessary temperature the pyrrole
form was completely converted into the isopyrrole form, which is
unacted on by these reagents. Finally, the desired result was
obtained by methylating the compound through the silver salt.
Five grams of the silver salt were prepared from the potassium salt
in the manner described on page 1532, and after being carefully
dried in an air-oven at 80° the salt was transferred to a flask
fitted with a reflux condenser, in which it was mixed with 100 c.c.
of carefully dried benzene containing excess of methyl iodide. The
flask was then heated on the water-bath for two hours, at the
end of which time the greater portion of the silver salt ha'd been
decomposed. The benzene sokition was then fil'tered and
evaporated, leaving an oily residue, which rapidly solidified. When
reci-ystallised from alcohol, it formed colourless prisms melting
at 120°:

01802 gave 0-3799 COg and 0-0940 HoO. C = 57-49; H = 5-79.
C10HJ2O3N2 requires 0 = 577; H = 5-8 per cent.

The methyl derivative is insoluble in cold aqueous potassium
hydroxide.

Ethyl Hydrogen a-Cyano-^-met]iyU]innoa(li2iate,
COoH-CHo-CH.3-C(:NMe)-CH(CN)'CO.Et.

This substance is formed by the hydrolysis of ethyl 2-keto-
l-mcthyltetrahydropyrrolidene-5-cyanoacetate by means of sodium
carbonate solution in the following way. Five grams of the
pyrrole derivative are mixed with 20 c.c. of a 10 per cent, solution
of sodium carbonate, and boiled until all has passed into solution
and no separation of oil takes place on cooling. The cold solution
is then acidified with hydrochloric acid, and the crystalline pre-
cipitate which separates is purified by recrystallisation from water.
When rapidly crystallised from this solvent, it forms lustrous
plates, but when allowed to separate slowly it is obtained in long,
slender needles. It melts at 155°, and gives off , gas when heated
to a high temperature:

0-1973 gave 0-3835 COo and 01120 H.O. C = 53-02; H-6-31.
C10HJ4O4X2 requires 0 = 531; 11 = 62 per cent.

The silver salt, OjoHjgO^NgAg, separates as a white, crystalline
precipitate when the calculated quantity of silver nitrate solution
is added to a neutral solution of the ammonium salt :

KEACTlOXS OF I.MlNO-COMI'OUXUS. PART X. 1537

0-2541 gave 00821 Ag. Ag = 32-31.

CjoHjyO^NoAg requires Ag = 32'43 per cent.

Ethyl hydrogen o-cyano-)3-methylimiuoadipate is reconverted into
ethyl 2-keto-l-methyItetrahydropyrrolidene-5-cyanoacctate on rapid
distillation under the ordinary pressure. The following analysis
was made of the product obtained in this way, which melted at
120°:

0-2248 gave 24-1 c.c. No at 12° and 750 mm. N = 12-6.
CjoHi^O^Ng requires N = 12-4 per cent.

The formation of methijlamine and ethyl hrjdrogen a-cyano-
fi-ketoadipate from ethyl hydrogen a-cyano-fi-metliyliminoadijjate. —
This transformation was effected by the action of potassium
hydroxide solution in the following way. Five grams of the imino-
compound were heated under the same conditions as described on
page 1530 for ten minutes, when steam was passed through the flask,
and the contents were finally cooled and acidified. The oil which
separated solidified on keeping, and on recrystallisation from dilute
alcohol yielded the characteristic crystals of ethyl hydrogen
o-cyano-)8-ketoadipate, melting at 104°, and giving a red coloration
with ferric chloride :

0-2401 gave 13-9 c.c. No at 18° and 761 mm. N = 6-7.
C9H11O5N requires N = 6-6 per cent.

The hydrochloric acid distillate was evaporated to a small bulk,
mixed with platinic chloride solution, and then with an equal
volume of alcohol. The yellow platinum salt which then separated
was collected and analysed :

0-2328 gave 0-0957 Pt. Pt = 4ri0.

(NH2Me,HCl)2PtCl4 requires Pt = 41-34 per cent.

The base was evidently therefore methylamine.

Much of the expense entailed by this research has been met by
grants from the Government Grant Committee of the Royal
Society and from the Research Fund of the Chemical Society, for
which we desire to express our indebtedness.

University,

Manchester,

VOL. XCV. 5 I

1538 .TAMES AND SUDBOROUGH :

CLXXIII. — Halogen Derivatives of Cinnamic Acid.
By Thomas Campbell James and John Joseph Sudborough.

A. — Attempted Resolution of a-Bromocinnamic Acids by means of

Strychnine.

As a rule an unsaturated acid of the type R'CHICH'COgH exists
in two well defined stereoisomeric forms, namely, the cis and the trans.
The existence of such pairs of isomerides is in complete harmony with
the theoretical views of van't HofE, and the only acid that exists in a
larger number of isomeric forms than could be predicted from van't
Hoff's views is cinnamic acid. The recent work of Biilmann (Ber.,
1909, 42, 182, 1443) indicates that certain of the isomerides of
cinnamic acid are polymorphous forms (compare also Erlenmeyer,
ibid., 502, 513, 521 ; Liebermann, ibid., 1027). According to Erlen-
meyer [Ber., 1905, 38, 3499 ; 1906, 39, 285, 1570), both a^^ocinnamic
acid and ordinary synthetical cinnamic acid yield two isomeric salts
with brucine, and by this method a. resolution of the two acids was
accomplished.

The subsequent work of Marckwald and Meth {Ber., 1906, 39,
2598) has shown that the two brucine salts derived from cinnamic
acid are not isomeric, but that the salt melting at 135° is an acid
salt, and the one melting at 113° a normal salt: Erlenmeyer's
presumed resolution of synthetical cinnamic acid appears to be
incorrect, and it is suggested by Marckwald that the same holds good
for the resolution of a^/ocinnamic acid.

We have made several experiments with alkaloidal salts of a-bromo-
cinnamic and a-bi-omott^Zocinnamic acids with the objecb of seeing
whether these acids can be resolved (compare Sudborough and Thomp-
son, Trans., 1903, 83, 1167). The strychnine salts proved to be the
most suitable, as they crystallise well from alcohol. In the case of the
a-broraoa^^o-acid we obtained two distinct crystalline salts, one melting
at 183^ (decomp.) and the other at 127°, but subsequent investigation
proved that the second salt was merely the hydrated form of the
first salt. Similar results were obtained in the case of strychnine
a-bromocinnamate.

Strychnine a- BromoaWocinnamate, CoiHg.^OgNgjCgHyOjBr. — 16'7 Grams
of finely powdered strychnine (1 mol.) were added to a solution of 11*35
grams of pure a-bromoa^/ocinnamic acid (1 mol.) in 500 c.c. of absolute
alcohol, and the whole warmed gently until a clear solution was
obtained.

After three days, clusters of slender, prismatic crystals had separated.
The mother liquor (a) was removed, and the crystals washed with

I

HALOGEN DERIVATIVES OF CINNAMIC ACID. 1539

absolute alcohol and dried. The weight of crystals was 17 2 grams, or
a 62 per cent, yield. The salt was crystallised three times from
absolute alcohol, but the melting point remained constant at 183°
(decomp.) :

0-3512 gave 0-1 197 AgBr. Br =14-50.

C2iH2202N2,C,jH^OoBr requires Br^ 14-26 per cent.

The salt did not lose in weight when heated at 127° for some time,
and was thus free from water or alcohol of crystallisation.

The salt was optically active. 1-250 Grams, made up to 50 c.c. with
absolute alcohol, gave a -1-684° at 18° in a 4-dcm. tube, whence
[a]l? -16-84°.

The mother liquor (a) from the above salt, on spontaneous evapora-
tion, yielded large, transparent crystals. These were washed with
alcohol and dried. The crystals melted at 127° to a clear liquid, but
when the temperature was raised slightly, the molten mass solidified
and melted again at 183° (decomp.) :

1-9115, heated at 127° for ten^minutes, lost 0-0G60. HoO = 3-45.
1-2196, „ „ 95° until constant, lost 0-0377. HgO = 3-09.
0-3660 gave 0-1200 AgBr. Br = 13-93.

C2iH2202N2,C3H-OoBr,H20 requires H2O = 3-11; Br = 13-82 per cent.
0'4132, dissolved in alcohol, required 20*0 c.c. of 0-03616iV^-baryta ;

Theory 19:7. 0-4862 required 23-1 c.c. ; Theory 23-2.
1-2500 grams, made up to 50 c.c. with absolute alcohol, gave

a- 1-658° in a 4-dcm. tube at 18°, whence [a]!,' - 16-58° ( ± 0-066°).

The same crystals were obtained when the salt was recrystallised
from 50 per cent, aqueous alcohol, or when a mixture of strychnine
and a-bromoa^^ocinnamic acid, or the anhydrous salt described above,
was crystallised from 50 per cent, alcohol.

The salts are more soluble in mixtures of alcohol and water than in
either of the pure liquids. The acid recovered from them melted at
120°, and was optically inactive.

Strychnine abrornocinnamate. C^^Uo.^O.^N^yO.^Jl^O^^r, was prepared
by dissolving 454 grams of the acid and 6'68 grams of strychnine
in 200 c.c. of absolute alcohol. After several hours, a quantity
of colourless plates were^deposited, which, when washed with alcohol
and dried in the air, formed a fine white powder melting at 182°.
Yield 6-45 grams.

The mother liquor gave a further yield of the same type of crystals,
and ultimately about 1-5 grams of clear, hard, prismatic needles.
These were stable when exposed to the air and melted at about 130°,
but then resolidified and melted again at 182°. Further examination
showed that they were a hydrated form of the salt, for they may be

5 I 2

1540 JAMES AND SUDBOROUGH:

obtained by recrystallising the anhydrous salt from 50 per cent,
alcohol.

Anhydrous SaU.—0-2Qi5 gave 0-0694 AgBr. Br = 14-44.
CoiH.^oO^Ng.CgHyOgBr requires Br = 14-26 per cent.

O'SOO, dissolved in alcohol, required 14-45 c.c. of 0-03664iV-baryta ;
Theory 14-6.

1-250 grams, made up to 50 c.c. with absolute alcohol, gave a + 0"47°
in a 4-dcm. tube at 22°, whence [a]'u + 4*7'^.

Hydrated ^S'a^^.— 0-5801 gave 0-1880 AgBr. Br= 13-79.

2-5672, heated at 130° for one hour, lost 0-0886. H^O = 3-45.

2-0760 „ „ 108° „ three hours, lost 0-0684. H20 = 3-29.
CoiH2202N2,C9Hy02Br,H20 requires Br =13-82; H20 = 3-ll per cent.

The difference in rotation between the strychnine salts of the two
stereoisomeric a-bromocinnamic acids is remarkable ([ajjj +4-7° and
— 16-84° respectively).

B. — Action of Alcoholic Potassium Hydroxide on d- and
l-aP-Dibromo-fi-phenylpropionic Acid.

Sudborough and Thompson (Trans., 1903, 83, 666) have determined
the proportions of a-bromocinnamic and «^^ocinnamic acids obtained
by the action of alkalis on (Z^a/3-dibromo-/3-phenylpropionic acid. We
have examined the action of alcoholic potassium hydroxide on d- and
Z-a^-dibromo-/3-phenylpropionic acids, and find that the ratio of the
two unsaturated acids formed is much the same as when the ordinary
inactive dibromo-acid is used, and that the acids thus obtained are
optically inactive.

We used Hirsch's method {Ber., 1894, 27, 883) for the preparation
of the active a^-dibromo-^-phenylpropionic acids. The rotation of the
pure acids is ±64°. As it was not essential for our purpose to obtain
the acids quite pure, we were content to use a c^-acid with [a]u +29°,
obtained by recrystallising the brucine salt twice from absolute
alcohol, and then decomposing with dilute hydrochloric acid. The
Z-acid obtained by extracting the cinchonidine salt of the (ZZ-acid
several times with boiling benzene, and decomposing the residue with
dilute hydrochloric acid, had [a]n — 38°.

The acids were treated with two equivalents of alcoholic potassium
hydroxide at 0°, and the products worked up in the manner
described already (Trans., 1903, 83, 674). The results are given in
the following table.

aj3-Dibromo-)3- Weight Weight of Weight of

jihenylproijiouic taken in o-bromo- o-bromo-

acid. [o]i,. grams. acid. aZZo-acid. Ratio

+ 29- 2-0 0-15 0-9 1:6

-38 2-0 0-16 0-86 1 : 5-5

-38 6-0 0-45 3-45 1:7-7

HALOGEN DERIVATIVES OF CINNAMIC ACID. 1541

The ratio obtained by Sudborough and Thompson from dl-aft-
dibromo-jS-phenyl propionic acid under similar conditions was 1 : 7"8.

The rather low values of the ratio obtained when only a small
quantity of the dibromo-acid was used is due to the solubility of the
allo-iicid in water.

C. — The Addition of Bromine to Esters of Cinnamic Acid.

By the addition of bromine to ethyl cinnamate under certain con-
tions, Michael (Ber., 1901, 34, 3660) obtained as much as 54 per
cent, of ethyl a/^ocinnamate dibromide melting at 28 — 30°.

Sudborough and Thompson (Trans., 1903, 83, 671) repeated some
of Michael's experiments, but obtained as chief product the ordinary
dibromide melting at 75 — 76°, only the merest traces of the allo-
compound being formed.

Michael and Smith have recently performed a number of experi-
ments on the bromination of the same ester (Amer. Chem. J., 1908,
39, 27), using a slight excess of bromine, and working in carbon
tetrachloride solution. In some of these experiments as much as 50
per cent, of the «Z^o-dibromide was obtained, but they were unable to
draw any general conclusions. They state that the yield of allo-
compound depends on such subtle conditions that they do not consider
the experiments as more than suggestive for future investigation. On
the whole, the best yields were obtained when the solutions were not
cooled, and where the bromine was added in portions. A comparison
of their experiments also indicates that an increase in the length of
time during which the mixture is kept tends to augment the yield of
aWo-compound.

We have made the following series of experiments :

Methyl Cinnamate and Bromine. — (1) 19*8 Grams of methyl cinna-
mate and 19 "8 grams of dry bromine were dissolved separately in 100
c.c. of dry carbon disulphide. The bromine solution was added
slowly in the dark at 0° to the ester solution, care being taken that
the temperature did not rise. The mixture was then kept in an open
vessel in the dark until all the solvent was removed, and the residual
product was extracted several times with small amounts of cold
carbon disulphide in order to extract the a//o-dibromide. The yield
of the latter was 5'6 per cent.

(2) Similar to 1. Yield, 5 '25 per cent.

(3) Similar to 1, but only 50 c.c. of solvent were used, and the
bromine solution was added quickly in diffused daylight. The
temperature rose to 35°. Yield, 16-0 per cent.

(4) Similar to 3, but 100 c.c. of carbon disulphide were used, and

1542 JAMES AND SUDBOROUGH :

the temperature rose to the boiling point of the solvent. Yield, 12-7
per cent.

(5) Similar to 3, but the solvent was moistened by the addition of a
drop of water. Yield, 12*2 per cent,

(6) Similar to 3, but the mixing was conducted in the evening, using
artificial light. Yield, 8'75 per cent.

(7) Carbon tetrachloride was used as solvent ; the bromine solution
was added quickly at the ordinary temperature in diffused daylight.
Y^ield, 16 5 per cent.

Ethyl Cinnamate and Bromine. — The ester used distilled at 260 — 264°
under atmospheric pressure ; in each experiment 20"7 grams of bromine
were used for 22*0 grams of ester, each dissolved in 50 c.c. of solvent.

(1) Carbon disulphide was used as solvent, and the bromine solution
was added rapidly in diffused daylight. The temperature rose to 43°.
Slight evolution of hydrogen bromide took place, but no trace of the
a^^o-dibromide could be isolated.

(2) Dry carbon tetrachloride was used as solvent, and the bromine
solution was added in three portions at intervals of three hours. The
admixture took place in the dark at 20 — 24°, and 7"0 per cent, of oily
dibromide was obtained.

(3) Similar to 2, but the temperature was kept at 0°, and the
addition occupied two days. Y'ield, 6*1 per cent.

(4) Similar to 2, but the two solutions were mixed at once, and the
temperature was allowed to rise. Y'^ield, 8*4 per cent.

Further experiments proved that methyl cinnamate dibromide
(m. p. 118°) is not transformed into the a^/o-dibromide (m. p. 56°)
when kept in contact with a solution of bromine in carbon disulphide
or carbon tetrachloride for two months either in daylight or in
the dark.

According to Erlenmeyer {Ber., 1909, 42, 505), the ethyl ester of
synthetical cinnamic acid is a mixture which can be partially resolved
into its components by fractional distillation under diminished pressure.
'We intend to examine the products formed by the addition of bromine
to the different fractions in order to determine whether it is the e.ster
used which produces the discrepancies between Michael's results
and our own.

D. — T/ie Action of Alkalis on the Dihromides of Methyl and Ethyl

aUoCinnamates.

Previous experiments (Trans., 1903, 83, 676) have shown that the
chief product obtained by the elimination of hydrogen bromide from
a^-dibromo-/3-phenylpropionic acid is a-bromoaZ^ocinnamic acid, the
isomeric a-bromo-acid (m. p. 131°; being formed to a very slight

HALOGEN DERIVATIVES OF CIXNAMIC ACID. 1543

extent. When, however, esters are substituted for the acid dibromide,
the chief product is the a-bi'omo-acid, and the yield of a-hroraoallo-
acid is considerably diminished. It is possible that the a-bromo«^^o-
acid is to be regarded as the normal product in both cases, but that
when esters are used the process of hydrolysis and elimination occur
simultaneously and produce vibrations within the molecules which
tend to cause the labile a-bromort^/o-acid to pass over into the more
stable a-bromo-acid.

The question as to the nature of the products formed by the
elimination of hydrogen bromide from the «^^o-dibromides is of
interest, and has received but little notice.

Michael {Ber., 1901, 34, 3666) states that by boiling 3 grams
of ethyl o^/ocinnamate dibromide (m. p. 28°) Avith alcoholic sodium
hydroxide solution he obtained 08 gram of a-bromoa^^o-acid (m. p.
120°) and 1*2 grams of a-bromo-acid (m. p. 131°).

We have made the following experiments :

(1) 5-6 Grams of methyl «Z^ocinnamate dibromide (m. p. 54 — 56°)
were treated with two equivalents of potassium hydroxide in alcohol
solution at 0°. The alcohol was subsequently removed by evaporation
at the ordinary temperature, and the a-bromo-acids separated by means
of their barium salts. 0"2 Gram of a-bromoa^^o-acid and 3 5 grams of
a-bromo-acid were obtained. Theoretical yield, 3'95 grams.

(2) Six grams of ester (m. p. 54 — 56°) gave 3'8 grams of a-bromo-acid
(m. p. 131°) and no trace of a bromoa^/o-acid. Theoretical yield,
4'2 grams.

(3) Ethyl a^^cinnamate dibromide was purified by heating to 40° and
filtering through glass wool with the aid of the pump. When cold it
solidified to a crystalline mass, m. p. 30 "P.

2*17 Grams, with two equivalents of potassium hydroxide in alcoholic
solution, gave 0"1 gram of a-bromoa^^o-acid and 1'05 grams of a-bromo-
acid. Theoretical yield, 1"46 grams.

These results indicate that the main product of the reaction is the
a-bromo-acid (m. p. 131°) ; in experiment (No. 2) no allo-aeid could bo
isolated, and in the others the amount was very small, and may be due
to admixture of the original a^Zo-dibromide with small amounts of the
isomeric dibromide, as it is extremely difficult to obtain these alio-
dibromides in a pure, state.

E. — Action of Organic Bases on a^-Dibromo-P-phenylpropionic Acid.

The only experiments conducted hitherto appear to be those of
Sudborough and Thompson (Trans., 1903, 83, 681), who obtained
cinnamic acid and bromostyrene by boiling an alcoholic solution of
dibromo-/3-phenylpropionic acid with dimethylaniline.

1544 HALOGEN DERIVATIVES OF CINNAMIC ACID.

We have repeated these experiments, and can confirm the results.
From 10 grams of the dibromo-acid, 1"5 grams of cinnamic acid were
obtained. After crystallisation from benzene, the acid melted at 133°;
it also crystallised from ether in aggregates of thin lamellfe resembling
synthetical cinnamic acid. The recovered base contained small
amounts of bromine.

Trimethyl amine. — A solution of 6 grams of dibromo-^-phenylpro-
pionic acid and 2-5 grams of trimethylamine in 25 c.c. of methyl
alcohol was boiled for 0*5 hour in a reflux apparatus. The product
was a mixture of 0*5 gram of a-bromocinnamic acid (m. p. 131°) and
an oil, probably bromostyrene. Another experiment was made by
keeping the alcoholic solution for forty days at the ordinary tem-
perature and then removing the alcohol ; an 80 per cent, yield of
mixed a-bromo-acids was obtained. These were separated by means of
their barium salts, when a 2 6 '5 per cent, yield of a-bromo-acids
(m. p. 131°) and a 47 '7 per cent, yield of a-bromoa/^ocinnamic acid
(m. p., after recrystallisation, 120°) wei-e obtained.

Diethylaniline. — When an alcoholic solution of a/5-dibromo-/3-
phenylpi'opionic acid (10 grams) was boiled for an hour with diethyl-
aniline (10 grams), 33 per cent, of the acid was recovered, and about
3 grams of an oil (bromostyrene) were formed.

Cinchonidine. — Eight grams of dibromo-;8-phenylpropionic acid and
17 grams of cinchonidine were heated for a few minutes with 75 c.c.
of absolute alcohol, and the clear solution kept for six weeks. 7*5 Grams
of unaltered dibromo-acid were recovered. A second experiment was
made by boiling the alcoholic solution of the dibromo-acid (10 grams)
and cinchonidine (22 grams) for 1-5 hours. The product left after the
removal of the alcohol was a gummy mass ; this was treated with
hydrochloric acid and shaken three times with ether. The ethereal
solution was washed with a little water, and then extracted with
dilute sodium carbonate solution. The aqueous alkaline solution was
acidified with moderately concentrated hydrochloric acid, and gave
1*0 gram of organic acids, which were separated by means of their
barium salts. The products obtained were bromostyrene, b. p.
215 — 220°, 4*7 grams = 79 percent., a-bromocinnamic acid, 0*55 gram =
7"5 per cent., and a-bromoa?^ocinnamic acid, 0*35 gram = 4*8 per cent.
Total, 92-5 per cent.

Quinine. — Ten grams of the dibromo-acid gave 4-1 grams of
bromostyrene and 0*6 gram of a-bromocinnamic acid.

Brucine. — Ten grams of dibromo-/3-phenylpropionic acid, 26 grams
of brucine, and 100 c.c. of absolute alcohol were heated for a few
minutes and then evaporated to dryness on the water-bath, the whole
operation taking some forty-five minutes. The products were bromo-

THE CONSTITUTION OF GLUCOSE DERIVATIVES. PART TI. 1545

styrene, 40 per cent., a-bromo-acid, 21 '7 per cent., and abromoaZ^o-acid
244 per cent. Total, 86 per cent.

In all these experiments with feeble bases and alkaloids, appreciable
amounts of bromostyrene are formed, but the most interesting result
is that in practically every case the ratio a-bromo-acid/a-bromort^Zo-acid
is much greater than when strong alkalis are used. Thus with
potassium hydroxide the ratio is one-seventh, whereas with trimethyl-
amine it is, roughly, one half.

We wish to express our thanks to the Eesearch Fund Committee
for a grant which has covered part of the cost of this investigation.

The Edwaud Davies Chemical Labokatoeies,
University College of "Wales,
Aberystwyth.

CLXXIV. — The Constitution of Glucose Derivatives.
Part II. Condensation Derivatives of Glucose with
A romatic A mino-compounds.

By James Colquhoun Irvine and Robert Gilmour, B.Sc.
(Carnegie Scholar).

The mutarotation displayed by glucoseanilide and tetramethyl
glucoseanilide has, in a previous communication (Trans., 1908, 93,
1429), been explained on the assumption that these compounds exist
in stereoisomeric interconvertible forms which possess the y-oxydic
linking characteristic of reducing sugars and glucosides. From
analogy it might be expected that the condensation compounds of
glucose with amino-bases generally, and also with amino-acids, should
be constituted in a similar fashion, and in the present paper we
describe the results obtained in the examination of glucose-/)-toluidide,
-j9-phenetidide, -^-naphthylamide, and -o-carboxyanilide. As Behrend
and his pupils are at present engaged in similar work on the glucose-
phenylhydrazones, we have not in the meantime extended our
observations on these compounds.

The glucose derivatives mentioned above have now been shown to
exist in interconvertible stereoisomeric forms which closely resemble
the a- and /3-glucoseanilides, and they may thus be similarly regarded
as derivatives of tlie sugar in its y-oxydic form. Compared with

1546 IRVINE AND GILMOUR: THE CONSTITUTION OF

what may be termed " normal glucosides," * the compounds mentioned
are peculiarly unstable, especially toward the action of hydrolytic
agents, and it is thus impossible to apply chemical methods in eluci-
dating their structure. Even the silver oxide reaction which has
proved efficacious with other sugar derivatives, resulted in the present
cases in molecular rupture, and thus evidence regarding constitution
was sought for in the physical study of the formation and intercon-
version of the various isomeric forms of the compounds. We have
prepared each of the above substances under conditions which permit
of observation of the changes in rotatory power undergone during the
condensations, and this has been supplemented by the detailed study
of the mutarotation of the products. The claim for regarding the
above compounds as y-oxides thus rests on analogy alone, but their
close similarity with the glucoseanilides, for which the y-oxydic
formula is supported by synthetical evidence {loc. cit.), leaves no
reasonable doubt that all the substances are similarly constituted.

Glucose-j^-toluidide.

This compound has already been prepared by Sorokin, who describes
it as melting at 100°, and showing a^, - 43'8° in methyl-alcoholic
solution. On adopting his method of preparation, which consists in
boiling an alcoholic solution of gluccsse with ^:)-toluidine and precipi-
tating the product with ether, we found that the success of the process
depends largely on the amount of water which is present. Using
anhydrous materials throughout, the product was a viscid syrup which
did not solidify, but, on the other hand, the use of 83 per cent,
alcohol as the solvent gave satisfactory yields of crystalline material.
The amount of the solvent alcohol and the quality of the ether used as
the precipitant are, however, important points. Pure dry ether gives
a product crystallising in square plates, whilst ordinary commercial
ether precipitates the compound in well-formed needles, apparently
identical with the form described by Sorokin. A third form, crystal-
lising in prisms, was obtained by boiling either of the above varieties
with a large excess of ethyl acetate. Although the toluidide is only
sparingly soluble in this solvent, the crystalline form of the undissolved
residue continually altered during this treatment, indicating that
the process involved simultaneous solution and crystallisation. The
detailed examination of this third variety showed that it is the
anhydrous form.

Examination of Glucose- f-toluidide Crystallising in Needles. — The
details of the preparation of this compound are as follows : Sixty grams

* That is, compounds in whicli the sugar residue is linked to the remaining
group through oxygen.

I

GLUCOSE DERIVATIVES. PART II. 1547

of powdered glucose were added to a solution of 1 20 grams of ;;-toluidine
in one litre of 83 per cent, alcohol, and dissolved at the boiling point.
After boiling for one hour, tbe solution was evaporated until 800 c.c.
of alcohol had been collected, and the residual syrup was then mixed
with four times its volume of ether. The oil solidilied almost imme-
diately to a mass of delicate needles, which were collected, washed
with ether, and dried in a vaouim desiccator. The .substance decom-
po.sed readily on heating, and the melting point, although considerably
higher than that quoted by Sorokin, was indefinite (115 — 120°).
Analysis of the air-dried material indicated the presence of one
molecule of water of crystallisation :

Found: C = 54-26; H = 7-37.

OjgHjgOgN.HaO requires 0 = 5435 ; H = 7-31 per cent.

In all the preparations the products were Ijevorotatory, and showed
downward mutarotation. When precipitated by ether as described
above, the first crops obtained were invariably more highly active than
succeeding crops, but the equilibrium values attained in solution were
fairly uniform. In determining the mutarotation, methyl alcohol was
used as tbe solvent, and the concentration was, as nearly as possible,
2'500 in each case.

Initial [o]^. Permauent [a]u.

Crop 1 -97-6° > -45-2°

,, 2 -87-5 >■ -44-9

,, 3 -21-8 > -450

^^
W e regard this Isevorotatory variety as the hydrated /3-form.

Examination of Glucose-^-toluidide Crystallising in Plates. — This

variety of the toluidide may be prepared by Sorokin's process, the

amount of 83 per cent, alcohol employed as a solvent being not more

than twelve times the weight of sugar used. With these proportions,

dry ether must be used in the precipitation of the product. The pure

compound, when recrystallised from anhydrous methyl alcohol, melted

without appreciable decomposition at 117 — 119°, and analysis

showed that half a molecule of water of crystallisation was

present :

Found: C = 56-00; H = 7-35.

CigHjgOsNjiHgO requires C = 56-11 ; H = 7-19 per cent.

The first crops of the compound to be precipitated contained excess
of the Isevo-form, whilst succeeding crops contained a larger proportion
of the dextro-isomeride than exists in the equilibrium mixture ;
mutarotation in opposite directions was thus observed.

Initial [af^\ Final [a]f . Initial [_a-\f.

Crop 1 -94-6° > -^1-r —

„ 2 _ -45-0 < -211''

1548 IRVINE AND GILMOUR: THE CONSTITUTION OF

The compound combined readily with an additional half-molecule of
water to give the inonoclinic vaiiety, the change being effected by
crystallisation either from water or fx'om dilute methyl alcohol. The
fact that during this treatment the compound gained about 3 per cent,
of its weight is also consistent with the idea that the change is due
to the addition of water. This transformation from the plate form to
the needle variety has little effect on the rotatory power of the com-
pound. This is seen whether we compare the initial values or the perma-
nent specific rotations attained in solution :

Initial [a]f°. Final [a]f.

Needle form -97-6° > -45-2°

Plate ,, -94-6 > -47-3°

These slight differences in rotatory power are somewhat greater
than the experimental error of our observations, but it is note-
worthy that the permanent values become identical if the concen-
trations be calculated in each case for the amount of the anhydrous
compound present in the solution.

As the initial specific rotation quoted above ( - 94"6°) was obtained
with a specimen which had been repeatedly crystallised from absolute
methyl alcohol, it probably approximates closely to the maximum
value for the partly hydrated /3-toluidide.

Examination of Glucose-p-toluidide Crijstallising in Prisms. — In our
experience the most convenient method of preparing anhydrous
glucose-^j-toluidide is to use f,nhydrous materials in Sorokin's process.
The product thus obtained was a syrup, which became crystalline
when boiled for about one hour with a large excess of ethyl acetate.
The residue then crystallised from methyl alcohol in long, slender
prisms, which analysis showed to be the anhydrous compound :

Found: C = 57'55; H = 7-15.

C13H19O5N requires C = 57'99 ; H = 7-06 per cent.

The compound may be converted into the hydrated varieties already
described by solution in dilute alcohol and removal of the solvent. In
this way a mixture of plates and needles was obtained, and on
repeating the process the needle form alone was finally produced.
Conversely, prolonged boiling of either of the hydrated forms with
ethyl acetate resulted in almost complete conversion into the anhydrous
compound. A 2 per cent, solution of the prismatic toluidide in methyl
alcohol was strongly dextrorotatory, the maximum value observed being
[a]?" 181*9°. The mutarotation was extremely rapid, particularly in
presence of traces of acid, the average end point being [a]j, - 45",
It was found possible to obtain a specimen of the compound containing
a greater proportion of the Isevo-form than exists in the equilibrium
mixture by evaporating the alcohol from a solution which had

GLUCOSE DERIVATIVES. PART II. 1549

attained the permanent rotatory power, and boiling the crystalline
residue with ethyl acetate. After boiling for one hour, the liquid
was filtered. The undissolved residue now gave a^, 163°, whilst the
filtrate yielded a crop showing [a]u — G9°. The two specimens were
identical in analytical composition, showed mutarotation in opposite
directions, and gave the same equilibrium value in solution. The
boiling with ethyl acetate evidently effected a transformation of the
Ijfivo- into the dextro-isomex'ide, and did not consist merely in the ex-
traction of one form by the solvent. This was shown by the fact that
on prolonged boiling the amount of the laevo-form present in the
-solution diminished, until ultimately practically the whole of the
material was deposited in the form of the sparingly soluble dextro-
variety.

The results of the above experiments therefore show that, when
prepared by the ordinary method, anhydrous glucose-;j-toluidide con-
tains excess of the dextrorotatory a-form ; on the other hand, the
^-isomeride is laevorotatory, and shows a ready tendency to crystallise
with water of crystallisation.

Optical Effect of Condensing Glucose with -p-Toluidine. — The polari-
metric study of the condensation of glucose with jo-toluidine afforded
evidence as to the mechanism of the reaction. Five grams of glucose
were dissolved in 50 c.c. of 83 per cent, alcohol, and the solution kept
for several days. Excess of ^>toluidine (8 grams) was then added,
and the liquid kept at 14°, daily observations of the rotation being
made :

Time in days.

a„ (2-(lcra. tube).

Time in days.

a I.

(2-dcm. tube)

0

+ 7-05°

O

+ 1 -40°

1

7-70

7

-7-75

2

5-00

10

-10-25

The well-marked increase and diminution in the dextro-sense
would correspond with the formation in the first instance of the
anhydrous prismatic a-form, which Avould undergo reversible change
to give the equilibinum mixture of the a- and /3-modifications. The
latter form is then, according to the amount of water present, partly
or completely hydrated, giving rise ultimately to the needle variety.

Effect of Boiling Ghccose-i^-toluidide with Ether. — In the case of the
glucoseanilides it was found possible to effect a partial separation of
the a- and /3-forms by extraction with a large excess of boiling ether.
On applying the same process to the /?-form of glucose-jt?-toluidide a
different result was, however, obtained. Even after prolonged boiling,
the ethereal filtrate was found to be quite inactive, and the extract
then contained only a small quantity of oil in solution. The rotation
of the undissolved residue nevertheless altered continuously during the
treatment, at first increasing in the Isevo-sense and afterwards dimin-

1550

IRVINE AND GILMOUR: THE CONSTITUTION OF

isbing, until ultimately the substance showed a distinct dextrorotation.
This change was not, however, due to interconversion of the a- and
y8-forms, but is attributable to extremel)' slow hydrolysis. This was
shown by the fact that the equilibrium values attained in solution by
specimens of the compound treated in this way also altered during the
process, showing a continuous fall in the Isevo-sense :

Time

in liours.

4

7
100

Initial «„.

-85-9°

-67-0

+ 4-9

Finr.l Oo.

-28-9"

-22 0

+ 5-8

It was also found that the nitrogen content diminished steadily
throughout the treatment with ether, and the above results are ex-
plained on the assumption that slow hydrolysis took place. The rate
of this hydrolysis naturally varied with the quantity and quality of
the ether used. With carefully purified ether, however, no alteration
in the optical values of the toluidide were observed when special pre-
cautions were taken to exclude moisture during the heating. The
result is interesting as indicating the extreme sensibility of these
compounds towards hydrolytic agents.

Glucose-'p-phenetidide.

Our experience with this compound is somewhat at variance * with
that recorded by Glaus and Ree (Chem. Centr., 1898, ii, G95), who
state that the substance crystallises, presumably in the anhydrous form,
in needles melting at 160°. No previous examination of the rotatory
powers of the compound seems to have been made. The method of
preparation followed by us in the first instance was exactly the same
as for glucose-p-toluidide. The crystalline product thus obtained
softened at 95° and melted completely, and decomposed between 110°iand
120°. Considerable difficulty was experienced in obtaining satisfactory
analytical figures for the phenetidide when prepared either by the
method mentioned above or by the process of slow condensation which
is subsequently described. When the crystalline substance was dried
in air, the figures obtained corresponded with the presence of one
molecule of water of crystallisation :

Found: C = 52-40; H = 7-30; OEt=]4-58.
^u^iOq1^,B.P requires C = 52-99 ; H = 726 ; OEt = 14-19 per cent.

The substance lost in weight when preserved in a vacuum desiccator,

* Other observers have had occasion to question the reliability of previous work
on tliis compound. In a recent paper, St. Mostowski (Bull. Acad. Sci. Cracow,
1909, 641) contradicts the generally accepted statement that glucosephenetidide
possesses powerful toxic properties.

GLUCOSE DERIVATIVES. PART II.

1551

and analyses of specimens dried in this way gave figures varying
between values calculated for the hydrated and anhydrous forms. On
heating for several hours at 60° in a vacuum, the loss in weight cor-
responded with the removal of half a molecule of water, and the
residue on combustion gave figures agreeing approximately with this
supposition :

Found: C = 53'92; H = 7-U.

Ci4H2iOgN,iH20 requires 0 = 54-54 ; H = 7-14 per cent.

All attempts to obtain the completely dehydrated form failed,
although the method of pi'eparation was modified in various ways.
Considering the discrepancy between our results and those quoted in
the literature, we redetermined the molecular weight in ethyl-alcoholic
solution by the ebullioscopic method and obtained a normal result :

Found : M.W. = 312 j Ci^H2iOgN,H20 requires M.W. = 317.

In every other respect our preparation resembled that described by
Claus and Ree.

The specific rotation of the hydrated compound in methyl-alcoholic
solution (c = 3'4660) was - 96'1°, but this rapidly altered to the constant
value, - 38 "3°. On account of the low melting point of the compound,
the usual method of increasing the proportion of the Isevo-form by
boiling with ethyl acetate could not be applied, as the phenetidide
fused under the liquid and the equilibrium mixture of the two forms
was thus obtained. It was also found that when boiled with specially
purified ether no transformation of the mutarotatory forms took place,
although the use of commercial ether, probably on account of
hydrolytic action, considerably increased the Isevorotation of the
undissolved residue.

The mutarotation mentioned above indicates the existence of a
dextrorotatory variety of the phenetidide, and this was confirmed by
observing the optical changes which took place during the condensation
of the sugar with the base. A 3 per cent, solution of glucose was pre-
pared in 83 per cent, alcohol, and 6 grams of /)-phenetidine were dissolved
in 100 c.c. of the solution. On keeping the liquid at 14°, it was found
that the rotation decreased continuously ; after six days the solution
was Isevorotatory, and on the eleventh day the product commenced to
crystallise in beautiful long needles. With higher concentrations the
condensation proceeded much more rapidly, and with a 9 per cent,
solution of the sugar the change was complete in about eight hours.
The following table contains the rotations then observed in a 2-dcm.
tube :

Time in minutes.

Od.

Time in minutes.

Od.

0

+ 6-16''

120

+ 3-94

30

5-90

240

-(-1-20

60

5-40

480

-3-00

1552 IRVINE AND GILMOUll: THE CONSTITUTION OF

The slow initial decrease in the first stages of the reaction is'
evidently followed by a more rapid diminution. The total optical
effect is due to : (1) formation in unequal amounts of the a- and /3-forms
of the phenetidide, (2) mutarotation of the uncombined sugar, (3)
mutarotation of the phenetidide formed. Taking these factors into
account, the readiest explanation of the above polarimetric results is
that the form of the phenetidide first produced has a dextrorotation
higher than that of glucose, and the reaction is thus brought into
line with the condensation of the sugar with jo-toluidine and with
j8-naphthylamine.

Glucose-ji'iiaphthylamide.

The usual method of condensing glucose with amino-compounds
proved efficacious in the preparation of glucose-;8-naphthylamide. A
solution of 20 grams of /3-naphthylamine in 300 c.c. of alcohol (83 per
cent.) was boiled under a condenser with 10 grams of glucose. After
one hour's treatment, the sugar had completely dissolved. Most of the
solvent was then removed, and a large excess of ether added to the
solution. A copious precipitate of delicate needles, closely resembling
glucose-/>-phenetidide, was at once deposited. The product, after
collection and washing with dry ether, melted sharply at 117°.
Analysis of the air-dried specimen gave :

Found: C = 59-20; H = 6-80 :

CjgH^gO^NjHgO requires 0 = 59-44; H = 6-50 per cent.

In different preparations the rotatory power of the compound was
faii'ly uniform, the initial value found for a 2'5 per cent, solution in
methyl alcohol varying between [a]b" - 111° and [a]?," -97°. Muta-
rotation invariably occurred with these solutions, the constant value
[ajo —48-1° being reached in each case. The compound therefore
exists in two stereoisomeric forms, one of which (the ^-form) is
strongly Itevo- and the other (the a-form) probably dextro-rotatory.

On boiling a specimen of the compound for five hours with a large
excess of ether, the specific rotation of the undissolved residue increased
from - 96-7° to - 118-7°. This behaviour is similar to that observed
with glucosetoluidide, and is no doubt attributable to the same causes.
As in this case the undissolved residue would contain free glucose, the
value mentioned above must be taken merely as an indication of the
fact that /3-glucose-/S-naphthylamide possesses a very high Isevo-
rotation.

Evidence that, in addition to the /3-isomeride, a dexti'orotatory
a-form exists was obtained in the polarimetric study of the formation
of the compound. A 3 per cent, solution of glucose in 83 per cent,
alcohol was prepared and allowed to attain the constant rotatory
power. Six grams of /3-naphthylamine were then dissolved in 100 c.c.

GLUCOSE DERIVATIVES, PART II. 1553

of this solution, the liquid ])eing afterwards maintained at 15" for
sever.il days. The dextrorotation at first increased rapidly and then
regularly diminished, the solution ultimately becoiuing hwvorotatory.

Time ill liours. a,, (■2-dcir. tube).
0 +2-94'

3 3-00

G 278

Time in lionrs. a„ (2-dcm. tiibi').
9 +2-45°

24 +l-0o

100 -1-50

. The rotation solution subsequently deposited the compound in well-
formed needles more than half an inch in length. Analysis showed
that in this case, also, the compound contains one molecule of water of
crystallisation. Other hydrated forms of the compound doubtless
exist, as when crystallised from ethyl acetate a mixture of needles and
plates was obtained. The latter variety could not be obtained
unmixed with the needle form, but from the analogy of glucose-p-
toluidide it probably contains half a molecule of water of crystallisa-
tion. It will thus be seen that in every respect glucosenaphthylamide
is closely analogous to the corresponding toluidide.

An attempt to condense glucose with a-naphthylamine led to no
definite result. The unaltered sugar was recovered in the crystalline
state and no condensation products could be detected.

Glucose-o-cao-boxyanilide.

It is already known that glucose condenses with 2 : 3-diaminobenzoic
acid, but does not react with other isomeric forms of the compound.
The constitution of the product has given rise to considerable dis-
cussion, and it is still doubtful if both of the amino-groups take part
in the reaction. There seems every reason to believe, however, that
the carboxyl group remains intact in the process. The problem is
naturally simplified by the substitution of a monoamino-acid for the
diamino-compound, and in the hope of obtaining some information
regarding the mechanism of the condensation of sugars with amino-
acids generally, we have prepared and examined glucose-o-carboxy-
anilide.

On boiling an alcoholic solution of glucose with anthranilic acid,
extensive decomposition takes place, and very little product is
obtained. At the ordinary temperature, however, the condensation
proceeds smoothly, and the change may thus be followed polarimetri-
cally. The results obtained in the following typical preparation
show that at 18° the change is rapid, and although the activity
decreases continuously, the diminution is comparatively slow in the
early stages of the reaction, thus indicating that the form first pro-
duced is more strongly dextrorotatory than glucose. A 9 per cent,
solution of glucose was kept until constant in rotation. Twenty grams

VOL. XCV. 5 K

1554

IRVINE AND GILMOUR : THE CONSTITUTION OF

of anthranilic acid were then dissolved in 150 c.c. of the solution,
which was at once placed in a thermostat at 18°, a polarimetric
sample being meanwhile kept at the same temperature in a 2-dcm,
jacketed tube.

The following optical changes were then observed :

Time in minutes.

Od.

Time in minutes.

Od.

0

+ 8-25°

60

+ 7-50

10

8-25

90

6-75

20

8-15

130

6-25

30

7-90

After twenty hours the solution was Isevorotatory, and subsequently
crystallisation of the product commenced. The compound separated
in long needles, which, after washing with dry ether, melted at
128 — 130°. Analysis of the air-diied product showed that one mole-
cule of water of crystallisation was present :

Found: C = 49-24; H = 5-95.

CigH^-O-NjHaO requires 0 = 49-21 ; H = 5-99 per cent.

A determination of the amount of combined water in the compound
was necessai-y, as the analytical figures quoted above do not exclude
the possibility of condensation of the sugar with the acid through
both the amino- and carboxy-groups, giving a product crystallising
with two molecules of water. On account of the instability of the
compound, this determination had to be conducted at 80° in a vacuum.
The substance then lost S'l per cent, of its weight, the calculated
I'esult for one molecule of water being 2-9 per cent.

Glucose-o-carhoxyanilide is sparingly soluble in water, readily so in
alcohol, and dissolves easily in sodium carbonate solution. The
aqueous solution reacts feebly acid towards litmus, and, owing to
molecular ' rupture, reduces Eehling's solution at the boiling point.
The formation of the compound evidently consists in condensation of
the constituents through the amino-group only, and the carboxy-group
remains intact. This was shown by the formation of a definite
sodium salt. On adding two molecular proportions of sodium ethoxide
to a 3 per cent, solution of the compound in absolute ethyl alcohol,
an abundant amorphous precipitate separated, which was rapidly
collected and washed with alcohol. The salt, which was highly
deliquescent, was dried until constant in weight in a vacuum
desiccator :

Found: Na = 7-ll.

Cj^gHjgO^NNa requires Na = 7-16 per cent.

The acid from which the sodium salt was derived must therefore
possess the structui-e CgHjjOg'NH-CgH^'CO^H.

This formation of a mono-sodium derivative from glucose-o-carboxy-

GLUCOSE DERIVATIVES. PART II. 1555

anilide not only confirms the presence of the carboxy-group, but has
some bearing on the constitution of the sodium glucosate. It is
evident that in the latter compound the metallic atom must occupy
the glucosidic position, as this is the only part of the sugar molecule
which is substituted in glucose-o-carboxyanilide. Any alternative
structure for sodium glucosate, other than tliat suggested, would in-
volve the formation of a disodium compound under the conditions of
the above experiment.

The optical study of glucose-o-carboxyanilide gave results closely
analogous to those obtained with the other compounds described in
this paper. All the preparations of the substance Avere dextro-
rotatory, and displayed extremely rapid mutarotatioa in the Isevo-
diiection, the permanent values beiug rather irregular, doubtless on
account of slight hydrolysis. The effect of boiling with ethyl acetate
was to increase the proportion of the dextrorotatory form, and it was
shown by analysis that this change was entirely due to stereochemical
alteration and not to partial dehydration of the hydrated com-
pound. The following typical example of these optical changes may
be given :

Solvent = methyl alcohol, c = 2-500, t = 20°.

Initial specific rotation : [a]'o -t-35'l°; permanent value, -FlTP.

After boiling for three hours with excess of ethyl acetate the same
specimen gave :

Initial specific rotation, -t-87"4°; permanent value, -fl4'5°.

The dextro-variety is therefore the form first produced, and is the
less soluble form. We propose the name a-glucose-o-carboxyanilide for
this dextro-form, and we consider that the interconversion of the two
isomerides is consistent with the idea that they contain the y-oxydic
linking.

The expenses of the above research were defrayed by a special
grant from the Carnegie Trust, for which the authors desire to express
their thanks.

Chemical Research Laboratory,

United College of St. Salvator and St. Leonard,

University of St. Andrews.

o K '2

1556 DUNSTAN AND THOLE: THE RELATION BETWEEN

CLXXV. — The Relation hetiveen Viscosity and Chemical
Constitution. Fart IV. Viscosity and Hydration
in Solution.

By Albert Ernest Dunstan and Ferdinand Bernard Thole.

The problem of the existence or the non-existence of complexes in
solution has in recent years been raised from the sphere of controversy
into the region of experimental vei'ity. In a monograph published by
Washburn [Tech. Qicart., 1908, 21, 360 et seq.) a critical summary is
given of the diverse methods on which so many chemists have based
the conclusion, that not only may a compound have a continued exis-
tence as such in a solution, but also it may, in accordance with the
laws of combination, form a more or less stable aggregate, which will,
in general, exist in equilibrium with the solvent and the simple com-
pound. During several years one of the present authors has been
collecting data on the viscosity of solutions, and has at various times
brought forward instances where viscosity-concentration curves attain
a maximum, and it has been found invariably to be the case that such
maxima occur at or near points of simple molecular composition.
Moreover, viscosity in general increases with molecular weight, and
liquids of known associative power have usually a considei-ably higher
viscosity than those of a simpler type. The conclusion that such
maxima indicate the existence of aggregates in the solution is thus a
natural one, and has been supported in recent years by the work of
Getman (/. Chim. phys., 1906,4, 386), Kremann and Ehrlich {Sitz-
ungsber. Wien. Akad., 1907, 116, 740), Beck and Ebbinghaus (Zeitsch.
physikal. Chem., 1907, 58, 436), and Tsakalotos {Bull. Soc. chim.,
1908, [iv], 3, 224, 242). Some objections have been raised, however,
against this view. Senter {Physical Chemistry, 1908, p. 306) draws
attention to the statement of Arrhenius that non-electrolytes in
general raise the viscosity of water, and hence a maximum point is
almost certain to be attained on the viscosity-concentration curve.
But it is precisely because combination or association goes on that the
viscosity rises even when the viscosity of the added component is less
than that of water. The maximum point is reached when the propor-
tions of the liquids are in the most favourable ratio demanded by the
laws of combination and of mass action. Washburn {loc. cit.), in
connexion with such changes of curvature, states "although the
existence of points of discontinuity can be denied, yet striking
irregularities sometimes occur," and further, quotes the work of
K lister and Kremann {Zeitsch. anorg. Chem., 1904, 41, 31), who found

I

VISCOSITY AND CHEMICAL CONSTITUTION'. rAlll' IV. 1557

very distinctly marked discontinuities in the curves connecting the
expansion coetificients with concentrations for aqueous solutions of
nitric acid. These irregularities occurred at the concentrations
required for the existence of HN03,H20 and IINOgjSHoO. Precisely
similar results were obtained by Kremann and Ehrlich [loc. cit., 749),
who determined the existence of the complex HgSO^jHoO, a hydrate,
the reality of which has been indicated by almost every variety of
physico-chemical method (Dunstan and Wilson, Trans., 1907, 91, 83).
Thus there can be little doubt as to the physical meaning of the
maximum points on such property-concentration curves. As to the
occurrence of minor changes of curvature, they may be denied
altogether (Washburn, p. 409), although this involves the denial of
the irreproachable accuracy of Pickering's work ; they may be set
down to erroneous methods of plotting (Hartley, Thomas, and
Applebey, Trans., 1908, 93, 541), or, finally, they may have a real
existence.

Much of the present conflicting data must be revised before
a final answer can be given. In the present communication the
authors have endeavoured to collect further evidence bearing on
the actual existence of genuine complexes in solution. To this end
four pairs of liquids have been examined, and these four pairs have
been chosen because so much work has been carried out with them at
various temperatures by a considerable number of investigators, for
example, Poisseule (Mem. Instit. Paris, 1846, 9, 433), Graham {Phil.
Trans., 1861, 151, 373), Wijkander {Wied. Beibl., 1879, 8, 3), Noack
{Ann. Phys. Chem., 1886, [iii], 27, 289), Traube {Ber., 1886, 19, 871),
Arrhenius {Zeitsch. jyhi/sikal. Chem., 1887, 1, 285), Varenne and
Godefroy {Compt. rend., 1903, 137, 993), Dunstan (Trans., 1904, 85,
817; 1905, 87, 11), and Getman {loc. cit.). With the exception of
very slight details, the curves obtained by the above chemists are
identical, and the general agreement that these liquid mixtures afford
well defined maxima is irreproachable.

The viscosity-concentration curves for these pairs of liquids have
been determined at 20°, 25°, and 30°, and the chief object has been to
settle whether any appreciable shift of maximum takes place with
varying temperature. Some difference of opinion seems to exist on
this point. Senter {loc. cit.) draws attention to this possible variation of
the position of the maximum point, and considers that any alteration
therein invalidates the conception of definite hydrates in solution. It
appears to the present authors that the lability of a complex in
solution is so great that any alteration in temperature or in concen-
tration may alter the equilibrium to a more or less pronounced extent.
For example :

1558 DUNSTAN AND THOLE : THE RELATION BETWEEN

Arrhenius found that the maximum point in the system
changed as follows :

CgHg-OH-HgO

Maximum at
per ceut. alcohol.

36
42
50

Traube: CH,-OII-

Maximum at per
cent, mctli}'! alcohol.
32
34
37
40

Temperature.

0°
17
55

HoO.

0°
10
20
30

Traube: C.Hg-OH-

- H2O.

Maximum

for ethyl alcohol.

Temperature

36

0'

41

10

46

20

46

30

CsH/OH - HoO.

Maximum

for ?i-propyl alcohol.

48

0°

50

10

54

20

Getman for the system methyl alcohol-water found the maximum
point practically unchanged for a range 0 — 63°, and so, also, Wijkander
observed in the case of the system acetic acid-water. Domke and
Bein for the system sulphuric acid-water noticed that the discon-
tinuities already referred to were invariant with regard to temperature
changes, and Kremann and Ehrlich showed that the viscosity maxi-
mum at H^SO^jHgO did not change within the limits 0 — 75° ; this
same maximum was further demonstrated by Domke and Bein,
Knietsch {Ber., 1901, 34, 4069), and Dunstan and Wilson. Moreover,
Kremann and Ehrlich noted that the maximum points in the systems
aniline-phenol and aniline-cresol were invariant through a temperature
range of 88°. The results brought forward in the present communica-
tion show that the variation of the maximum point in the four cases
specified is so small as to be almost negligible. It is certainly difficult
to demonstrate any appreciable change on a curve. The conclusion
seems to be that, not only do these aggregates exist in solution, but
also they have a certain temperature range of stability, which is
greater for aqueous solutions of acids than for similar solutions of
alcohols.

Experimental.

The method and apparatus have been described previously (Trans.,
1904,85,817; 1905,87, 11; 1907, 91, 1730). New stop-watches
supplied and kept in order by Messrs. Dent have been used, and
temperature variations have been kept within 0"01° by means of a
lai'ge thermoregulator checked by a Beckmann thermometer. Follow-
ing a suggestion by Hartley, conductivity water has been employed
both as a solvent and for rinsing the viscometers. The materials were '
Kahlbaum's purest preparations. Appropriate dehydration and
fractionation were employed.

VISCOSITY AND CHEMICAL CONSTITUTION. PART IV. 1559

Methyl Alcohol (b. p. 65-47765 mm.) and Water.

20".

25°

30"

Per cent.
CHj-OH.

8p. gr.

V-

Sp. gr.

V-

Sp. gr. 7j.

100-00

0-7923

0-005852

0-7878

0-005525

0-7835

0-005151

79-64

0-8481

001115

0-8435

0-01003

0-8391

0-009098

58-61

0-8977

0-01593

0-8940

0-01399

0-8901

0-01249

37-82

0-9384

001816

0-9355

0-01567

0-9325

0-01379

19-74

0-9671

O-0ir<87

0-9650

0-01378

0-9628

001198

0-00

0-9983

0-01002

0-9972

0-00891

0-9958

0-00798

Ethyl Alcohol (b.

p. 79-2777

2 mm.) and Water.

Per cent.

CoHs-OH.

99-20

0-79-22

0 01241

0-7876

0-01115

0-7832

0 009905

78-09

0-8481

0-02004

0-8439

0-01804

0-8399

0-01530

61-85

0-8871

0-02510

0-8828

0-02173

0-8786

0-01834

45-57

0-9237

00275^7

0-9266

0-0-2351

0-9165

0-01987

39-65

0-9359

0-02789

0-9323

0-02343

0-9293

0-01986

20-71

0-9677

0-02162

0-9654

0-018-29

0-9629

0-01505

0-00

0-9983

0-01002

0-9972

0-00891

0-9958

0-00798

n- Propyl

Alcohol

(b. p. 97-77

759 mm.)

and Water

Per cent.

CaH/OH.

100-00

0-8057

0-02180

0-8011

0-01936

0-7970

0-01736

73-1-'}

0-8623

0 02938

0-8584

0-02509

0-8543

0-02169

59-38

0-8918

0-03148

0-8867

0-02652

0-8831

0-02306

28-62

0-9536

0-0-2548

0-9494

0-02118

0-9476

0-01812

17-40

0-9746

0-02010

0-9723

0 01697

0-9699

0-01440

0 00

0-9983

0-01002

0-9972

0-00891

0-9958

0-00798

Acetic Acid (b. p.

118—118-5

7759 mm

.) and Water.

Per cent.

C^H.Oo.

99-15

1 -0522

0-01338

1-0466

0-01223

1-0407

0-01140

80 00

1-0699

0-02675

1-0647

0-02319

1-0596

0-0-2064

60-80

1-0648

0-02392

1-0602

0-02077

1-0557

0-01842

35-17

1-0433

0-01742

1-0401

0-111529

1-0377

0-01361

19-88

1-0260

0 01407

1-0233

0-01234

1-0209

0-01099

0-00

0-9983

0-01002

0-9972

0 00891

0-9958

0-00798

An examination of the viscosity-concentration curves (Figs. 1 and 2)
shows that in each case * the set of three curves affords the same
maximum point in agreement -n-ith Getman. The slight differences
between these results and those of Traube at the same range of tem-
perature amount only to 2-7 per cent, for methyl alcohol, 3-3 per cent,
for ethyl alcohol, and 3 per cent, for n-propyl alcohol. It is evident
that these small amounts might easily be caused by errors in plotting
the curves. Further, it should be noticed that the curves flatten
considerably as the temperature rises, the equilibrium alcohol xH^O Z^

* The curves for methyl and n-propyl alcohols are precisely similar in character
to that for ethyl alcohol, and are therefore not reproduced.

1560

DUNSTAN AND THOLE : THE RELATION BETWEEN

alcohol + rcHoO tends to the vanishing point ; indeed, Getman found
that at 65° the methyl alcohol- water curve was not far removed from a
straight line. This most important observation brings out still more
forcibly the authors' contention that an explanation of maximum
points is to be sought for in complex formation, for obviously at
sufficiently high temperatures such association would be largely
inhibited. A consideration of the curves shows that the viscosity
temperature-coefficient for the pure components is relatively small,
but that it progressively increases up to the maximum point. Now

Fig. 1.

I

0-02800

0-02400

0-02000

0-01600

0-01200

0-00800

0 ^ —

\

\\

/

/

\\\

/ /

"//

/

^

/

20 40 60

Percentage of acetic acid.

80

100

this quantity, d-qjdO, gives a further indication of the validity of the
authors' contention. In the case of all associated liquids, d-qjdd is
much greater than for unimolecular compounds.

Liquid. drildd for 10—0°.

Methyl alcohol 0-00127

Ethyl „ 0-00321

n-Propyl ,, 0-00965

Proiiionic acid 0-00333

Methyl formate 0-00045

Ethyl ,, 0-00057

Propyl chloride 000056

Methyl iodide 0-00058

(

VISCOSITY AND CHEMICAL CONSTITUTION. PART IV. 1561

Thus the vahie of the temperature-coefficient is a certain test for
association.

Consider now the values for dT^jdO in the cases of the four pairs of
liquids chosen.

Liquid pair.
H..0— CIl3'C0..H ...

H^O— CH.,-OH

HoO— C.ais'OH

H.'O— CJH/OH

Value of
d-nidd at 20—30°
0-0061U
0-00537
0-00780
0-00900

FiQ. 2.

0-02700

002300

»' 0-01900

0-01500

0-01100

0-00700

20 40 60

Percentage of ethyl alcohol.

100

The relatively great value for the last-mentioned pair is due to the
lower stability of the complex, and the enhanced value of the vi.scosity
itself at the maximum is explicable on two covints : (1) the larger
molecular volume, (2) the greater asymmetry of the complex.

Physical Chemistry Laboratory,
Technical College,
East Ham.

1562 CUNNINGHAM AND PERKIN :

CLXXVI. — Shidies on the Cohaltimtrites.
By Mary Cunningham and Frederick Moll-wo Perkin.

C oh altinit rites of Organic Amines.

As ammonium and potassium cobaltinitrites are very insoluble
salts and are readily prepared by the interaction of ammonium
or potassium salts respectively and sodium cobaltinitrite, it seemed
that in all probability primary amines would react in a similar
manner, and it also appeared likely that there would be a difiFerence
in the action of primary, secondary, and tertiary amines, in which
case sodium cobaltinitrite could be employed as a reagent for
distinguishing between the different classes of amines. Indeed,
it was found that when a concentrated solution of a salt of a
primary amine was added to a concentrated solution of sodium
cobaltinitrite, a crystalline compound was precipitated having the
foi'mula (AlldSrH3)3Co(N02)6. The compounds, however, are not
very stable, and must be removed from the mother liquor, washed,
and dried on a porous plate as quickly as possible. Secondary
amines of the aliphatic series give a similar precipitate, but as a
rule they are much more soluble, and consequently very highly
concentrated solutions both of the amine and sodium cobaltinitrite
must be employed; it is also advantageous to cool the solutions
with ice. Tertiary amines, as might be expected, have no action.
With aromatic amines the reaction is rather different, the
primary aromatic amines giving compounds which have the general
formUla (Ph'NH3)3Co(N02)6- Generally speaking, they are much
less stable than the compounds produced with the aliphatic amines.
Secondary aromatic amines yield a precipitate which almost imme-
diately decomposes, a nitroso-compound being formed. With
methylaniline, nitrosomethylaniline is produced, and dimethyl-
aniline yields j'-nitrosodimethylaniline, so that, in the case of the
aromatic series, we really have a method for distinguishing between
primary, secondary, and tertiary amines.

Inorganic Cobaltinitrites.

Potassium cobaltinitrite is one of the longest known of the
cobaltinitrites, but there appears some little doubt as to its actual
composition when prepared by the addition of a solution of a
potassium salt to a solution of sodium cobaltinitrite, the formula
being variously given as K3Co(N02)c, and NaK2Co(N02)6,H20-

Rosenheim and Koppel (Zeitsch. anorg. Chem., 1898, 17, 42),

I

STUDIES OX THE COBALTINITRITES. 1563

who prepared it under conditions in which there could be no sodium
present, by suspending pure cobalt carbonate in a small quantity
of water, adding the calculated quantity of potassium hydroxide,
carbonate, or nitrite, and then passing in nitrogen trioxide prepared
from arsenious oxide and nitric acid, obtained a compound having
the formula K3Co(N02)c. Adie (Trans., 1900, 77, 1076) added
a potassium salt to a solution of sodium cobaltinitrite, and obtained
a compound to which he gave the formula K2NaCo(N02)c)H20.
None of these authors, however, started with the pure sodium
salt, but wc have succeeded in preparing pure sodium cobaltinitrite,
and analysis showed it to possess the formula Na3Co(N02)G-

Experiments were then undertaken, employing this pure product
as starting material, in order to ascertain whether potassium
cobaltinitrite is the tripotassium salt or the dipotassium sodium
compound. We find that if excess of a potassium salt is present,
the tripotassium cobaltinitrite, K3Co(NOo)g, is formed, but that
with excess of sodium cobaltinitrite the salt K2NaCo(N02)(5 is
produced ; when neither is in considerable excess the analytical
figures show that frequently a mixture of the two salts is obtained.

Apparently Adie (loc. cit.) always employed an excess of the
sodium salt, a solution of which he prepared, but did not isolate
the solid compound, and this accounts for his analytical numbers.
The salts obtained by us did not, as a rule, contain water of
crystallisation.

We do not consider that the precipitation of potassium
cobaltinitrite is a method which can be recommended for the
analysis of potassium or cobalt compounds. In the first place, the
precipitate may be a mixture of the ti'i- and di-potassium salts.
Secondly, the potassium salt is extremely difficult to wash. It
will, in the first place, settle fairly well, and can easily be
washed once by decantation. On filling up the vessel with water,
however, the precipitate settles only slowly. On the third
washing, it settles still less satisfactorily, and shows a strong
tendency to become colloidal. Finally, it becomes almost an
impossibility to filter it satisfactorily. Adie (loc. cit.) also refers
to the difficulty of obtaining a clear filtrate, although he recom-
" mends the use of the salt in analysis.

We have also prepared and analysed silver cobaltinitrite; this
substance, according to Rosenheim and Koppel (Zeitsch. anorg.
Chevi., 1898, 17, 43), is not formed by the addition of sodium
cobaltinitrite to silver salts, silver nitrite being produced.

Lead cobaltinitrite has also been prepared, and we find that
when freshly precipitated it contains varying amounts of water
of crystallisation, which, however, are gradually lost when it is kept

1564 CUNNINGHAM AND PERKIN :

in a desiccator over phosphoric oxide until it finally contains four
molecular proportions.

Thallium cobaltinitrite has the formula Tl3Co(NOo)6.

Experimental.
M ethylamine Gohaltinitrite, (CH3*NH3)3Co(N02)6-

To a nearly saturated solution of methylamine hydrochloride
an excess of a nearly saturated sokition of pure sodium cobalti-
nitrite "was added. Almost immediately a deep yellow, crystalline
precipitate was produced. After stirring for three or four minutes,
it was collected by the aid of the pump and rapidly washed with
a very small quantity of ice-cold water and then with 50 per cent,
alcohol. It was then spread on a porous plate, from which it was
removed in the course of an hour or so and placed in an evacuated
desiccator over sulphuric acid or phosphoric oxide. The yellow
powder so obtained is quite stable when kept free from moisture,
but in presence of even a trace it slowly decomposes with evolu-
tion of nitrous fumes, forming a red, pasty mass; this contains a
small quantity of an oily liquid, which has an odour rather
resembling that of nitromethane, and may possibly be this sub-
stance, but the quantities obtained were too small to examine.
On heating, the substance gradually decomposes and shows no
definite melting point. Methylamine cobaltinitrite is extremely
soluble in water, and is at once decomposed by organic solvents.
It can, however, be precipitated in presence of acetic acid. It
decomposes violently with strong mineral acids; dilute acids
decompose it with evolution of nitrous fumes.

For analysis, a weighed quantity was moistened with concen-
trated sulphuric acid and heated until all the nitrous fumes were
driven off. To drive off all the nitrous fumes, it is necessary to
heat until fumes of sulphuric acid are also evolved. The cobalt
was then deposited electrolytically. A platinum gauze cathode
and rotating anode were employed, and the cobalt was deposited
in about half an hour.

Before electrolysis, the acid solution was diluted with water,
rendered faintly alkaline with ammonia, then faintly acid with
phosphoric acid, and about 5 grams of sodium dihydrogen phosphate
were added. It was found that if the nitrite was not completely
decomposed, the electrolysis required several hours, and the results
were not satisfactory :

Found, Co = 13-57.

C3HJ8OJ2N9C0 requires Co = 13'68 per cent.

STUDIES ON THE COB ALTI NITRITES. 1565

Ethylamine Cohaltinitrite,^ (C2H5*NH3)3Co(N02)c.

This was prepared in a similar manner to that adopted in the
previous case. It consists of small, glistening, orange-coloured
needles, and in properties closely resembles the methylamine com-
pound :

Found, Co = 12-80.

C6H24O12N9C0 requires Co = 12-47 per cent.

Diethylamine Cohaltinitrite, [(C2H5)2NH2]3Co(N02)6.

Diethylamine hydrochloride reacts with a concentrated solution
of sodium cohaltinitrite, yielding an orange-yellow, crystalline com-
pound, which is very similar in properties to the cobaltiuitrites of
the primary amines. It is, however, readily soluble in acetic acid,
whereas the primary cobaltiuitrites are not :

Found, Co = 10-62.

Ci2H3eOi2N9Co requires Co = 1059 per cent.

Aniline Cohaltinitrite, (CgH5*NH3)3Co(N02)6.

Owing to its extreme instability in presence of water, this sub-
stance is much more difficvilt to prepare than the cobaltinitrites of
the aliphatic amines. Quantities of aniline hydrochloride and
sodium cohaltinitrite corresponding with the equation :

3CcH5-NHo,HCl + Na3Co(NOo)6 = (CcH5-NHo)3Co(NOo)6 + 3NaCl
were dissolved separately in as little ice-cold water as possible. The
solutions were then mixed in a beaker surrounded with ice, stirred
for a few minutes, and filtered as quickly as possible. The
product, after being washed with a little ice-cold water, was trans-
ferred to a porous plate and placed in a desiccator. When dry, it
was removed from the porous plate and kept in a desiccator over
phosphoric oxide. Even when working in this rapid manner it
is not always possible to prevent the comjDound decomposing; if,
however, it is once quite dry, it will keep for some time.

The product is a yellow, crystalline powder, which becomes black
in a few days even when kept in a desiccator. It is fairly readily
soluble in water, but cannot be recrystallised from this solvent.
All organic solvents decompose it. If attempts are made to wash
the substance with alcohol or ether a tarry product is produced.

Very considerable difficulty was experienced in analysing this

* This substance has ah-eady been prepared by K. A. Hofmann and 0. Burger
{Ber., 1907, 40, 329S) by suspending cobalt carbonate in water, adding ethylamine,
and glassing in nitrogen trioxide.

1566 CUNNINGHAM AND PERKIN :

substance, because concentrated sulphuric acid decomposes it -witli
extreme violence, and dilute sulphuric acid has very little action
on it, except when boiled with it for some time, and then the
tarry products produced make it difficult to filter the solution.
The most suitable method was found to be to mix the substance
with dilute sulphuric acid, and then to add concentrated acid
drop by drop. This prevented explosive decomposition, and the
substance dissolved with a deep red coloration. The solution was
then rendered strongly alkaline with ammonia, sodium dihydrogen
phosphate added, and a few drops of 10 per cent, phosphoric acid
to make the solution faintly acid. It was then electrolysed, using
a rotating anode and a gauze cathode. With a current of about
two amperes, the deposition was complete in about half an hour :

Found, C = 34-92; H = 4-78; N = 20-21; Co = 9-41.
C18H24O12N9C0 requires C = 35-00; H = 3-89; N = 20-42; Co = 9-56

per cent.

^-Toluidine Cobaltinitrite, (CH3'CgH4'NH3)3Co(N02)6.

This substance was prepared in a similar manner to the aniline
compound. It forms orange-yellow needles, and resembles the
aniline compound in properties. It was analysed, with the follow-
ing result:

Found, Co = 9-49.

^211^30^:2^9^0 requires Co = 8-95 per cent.

Tp-Bromoaniline Cobaltinitrite, (C6H4Br*NH3)3Co(N02)6.

This compound is much more stable than either of the preceding.
It is an orange-yellow substance, forming needle-shaped crystals,
which are only sparingly soluble in water; there is consequently
no difficulty in washing it. It is decomposed by organic solvents,
but can be kept for weeks in a desiccator without decomposition.
When added to concentrated sulphuric acid it inflames :

Found, Co = 6-68.

Cj8H2iOi2N9Br3Co requires Co = 6-91 per cent.

The nitroanilines give no precipitate with sodium cobaltinitrite;
probably they do" not react owing to their negative character.

Methylaniline. — When a concentrated solution of methylaniline
hydrochloride is cooled in ice and a similarly cooled solution of
sodium cobaltinitrite added to it, a yellow precipitate is produced,
which, however, almost immediately decomposes with the formation
of an oil. The decomposition is so rapid that it is not possible to
collect the substance. The oil was extracted with ether, and the

I

w

STUDIES ON THE COBALTlNlTRlTES. 1567

ethereal solution well washed with water and aqueous sodium
carbonate; on evaporating the ether, a yellow oil was obtained
which gave Liebermanns reaction ; it was therefore a nitroso-
compound.

This decomposition of the cobaltinitrite with formation of the
nitroso-compound was not noticed with the aliphatic secondary
amines.

. Dimethijlaniline. — On adding a concentrated solution of
dimethylaniline in acetic acid to an aqueous solution of sodium
cobaltinitrite, a dirty yellow precipitate is formed, which, on
rendering the solution alkaline with sodium carbonate, gives a
deep green solution. If this solution is extracted with ether and
the ethereal solution evaporated, crystals of ^j-nitrosodimethyl-
aniline are produced.

Potassium Gohaltinitrite.

On adding an excess of a solution of sodium cobaltinitrite to a
solution of a potassium salt, a canary-yellow precipitate is at once
produced. This rapidly settles, but is very difficult to wash free
from sodium salts, owing to its tendency to become colloidal. The
well-washed substance was spread on a porous plate, and, when
dry, placed in an evacuated desiccator over sulphuric acid for
twenty-four hours. For analysis the substance was treated with
a small quantity of concentrated sulphuric acid, and heated in a
platinvim basin until white fumes of sulphuric acid were evolved.
It was then cooled, water added, and, after the addition of excess
of ammonia, electrolysed.

The potassium was estimated by treating a separate portion with
hydrochloric acid and precipitating as potassium platinichloride.
This method was found to be more satisfactory than evaporating
the electrolysed solution to dryness and expelling the ammonium
salts by ignition.

It has already been mentioned on p. 1563 that the constitution
of the potassium salt varies, depending on whether the sodium
cobaltinitrite or the potassium salt is in excess.

The following analyses, taken from a large number of deter-
minations, bear this out. In the first case, the potassium salt was
in excess. In the second case, an excess of the sodium salt was
present, and in the third and fourth cases the proportions were
about equal; these last show that the substance obtained was a
mixture of tripotassium cobaltinitrite and of dipotassium sodium
cobaltinitrite :

I. Found, Co = 13-25; K = 25-55.

K3Co(NO.)g requires Co = 13-05; K = 25-88 per cent.

1568 CUNNINGHAM AND PERKIN :

II. Found, Co = (i) 13-7, (ii) ISG; K = 17-78.
KoNaCo(NOo)c requires Co = 13-53; K = 17-88 per cent.

III. Found, K = 19-77. IV. Found, K = 20-71.

Sodium Cohaltinitrite.

Sodium nitrite (150 grams) is dissolved in hot water (150 c.c),
and the solution cooled to about 45° to 50°, when cobalt nitrate
(50 grams) is added, and the mixture stirred until the salt has
dissolved. Glacial acetic acid (25 c.c.) is now added, and after
thoroughly shading, the mixture is kept for twenty minutes. If
necessary, it is filtered from traces of potassium cohaltinitrite, due
to the presence of potassium salt in the sodium nitrite. A rapid
current of air is then aspirated through the filtrate for half an
hour to remove oxides of nitrogen, and then 95 per cent, alcohol
(150 c.c.) is added, the solution being shaken during the addition.
It is then shaken occasionally for an hour, and the voluminous
precipitate of sodium cohaltinitrite collected with the aid of the
pump. It is then washed once with a small quantity of 60 per
cent, alcohol, and two or three times with 95 per cent, alcohol, and
finally dried on a porous plate. The yield is about 60 per cent,
of the theoretical. An analysis of the air-dried product showed
it to have the composition Na3Co(N02)6 :

Found, Co = 14-41; Na = 16-98.

]Sra3Co(N02)c requires Co = 14-52; Na = 17-09 per cent.

In Dammer's Haiidhuch (Vol. 4), the formula is given as
Na3Co(N02)6>2|H20, but in all probability the substance had not
been properly dried before analysis, or it may be that washing
with alcohol, as we find advisable, removes water of crystallisation,
which would otherwise be present. The compound is a pale orange-
yellow, crystalline powder, extremely soluble in water, from which,
however, it can be reprecipitated by the addition of much alcohol.

Silver Cohaltinitrite.

On adding a solution of silver nitrate to a concentrated solution
of sodium cohaltinitrite, an orange-yellow precipitate is produced.
This salt is fairly soluble in water, and was therefore purified by
washing it with 50 per cent, alcohol. For analysis, the salt was
decomposed with nitric acid, the silver precipitated as chloride,
which was washed, dissolved in potassium cyanide, and the silver
deposited electrolytically. The solution containing the cobalt was
evaporated to dryness, treated with sulphuric acid, and heated to

STUDIES ON THE COBALTINITRITES. 1569

expel nitric acid. It was then diluted, rendered alkaline with
ammonia, and electrolysed :

Found, Ag = 49-08; Co = 900.

Ag3Cj(N02)c requires Ag = 49"14; Co = 8"95 per cent.

Thallium Cobaltinitrite.

This, prepared by mixing solutions of thallium carbonate and
sodium cobaltinitrite, is bright scarlet. It has already been
described by Jorgensen (Zeitsch. anorg. Chem., 1894, 5, 146), but
as, apparently, it was not analysed, we estimated the thallium
electrolytically. The compound was decomposed with nitric acid
and electrolysed, using a mercury cathode and a rotating anode :

Found, Tl = 64-4; Co = 6-12.

Tl3Co(N02)6 requires Tl = 64-62; Co = 6-23 per cent.

Lead cobaltinitrite is easily prepared by adding a solution of a
lead salt to a solution of sodium cobaltinitrite. It is an orange-
yellow, semi-crystalline powder, which is very sparingly soluble in
water. The substance was analysed by decomposing it with nitric
acid, and the solution made up so that it contained about 30 per
cent, of nitric acid. It was then electrolysed, using a roughened
platinum dish as anode, and weighed as lead peroxide. We had
great difficulty in obtaining concordant results, but we found that
this was due to the fact that when freshly precipitated it contained
variable quantities of water, which, however, was gradually lost
when the compound was kept in a desiccator over phosphoric oxide,
until finally it contained 4H2O. Rosenheim and Koppel (^Zeitsch.
anorg. Chem., 1898, 17, 48) found 12HoO in a specimen prepared
by them. We have analysed samples containing about llHgO,
but we never obtained one with 12HoO. The following figures were

! obtained with samples which had been dried for from two to three
days in a desiccator containing phosphoric oxide:
Found, Pb = (i) 44-91, (ii) 44-78.

Pb3[Co(NOo)c]254H2C) requires Pb = 45-56 per cent.
When solutions of sodium cobaltinitrite are added to concen-
trated solutions of carbamide, nitrogen is evolved. With hydroxyl-
amine, the evolution of nitrogen is very rapid. With semicarbazide,
I ammonium cobaltinitrite is precipitated.

Chemical Department,
Borough Polytechnic Institute,
London, S.E.

VOL. XCV. 5 L

1570 HILDITCH : THE EFFECT OF CONTIGUOUS

CLXXVIL — The Effect of Contiguous Unsaturated
Groups on Optical Activity. Part II. Acids
containing Tivo Adjacent Ethenoid Groups.

By Thomas Percy Hilditch (1851 Exhibition Scholar).

In continuation of the scheme outlined in the first communication of
this series (Trans., 1909, 95, 331), the author has examined some
optically active derivatives containing the unsaturated system

•ch:ch-ch:ch-.

A considerable number of compounds have been utilised, in which, on
the one hand, the optically active part of the molecule, and on the
other, the groups adjacent to the conjugated ethenoid system, have
been varied. The corresponding reduction products have also been
prepared, and since in all cases the rotatory power of the conjugated
derivative varies in the same manner with respect to the reduced
compounds, it follows that the constant effect produced must be due
to the adjacent ethylenic groups, the only system which remains
unchanged throughout the examples studied.

An objection to the use of carboxylic acids lies in the fact that an
unsaturated carboxyl residue must invariably intervene between the
optically active alcohol or base and the studied unsaturated system,
and possibly exert varying effects in different instances, but this
failing may to a great extent be overcome by consideration of the
rotatory power of the reduced esters or salts.

Four different series of acids were used, namely :

(a) Sorbic acid, CHMelCH-CHiCH-CO.H, etc. ;

\h) Muconic acid, COaH-CHICH-CHICH-COgH, etc.;

(fi) Piperic acid, CB.^'.O^.Q^'B.^-QW.CB.'GB.'.CB.-CO^^, etc. ; and

\d) Cinnamylidenemalonic acid, CHPh:CH-CH:C(C02H)2, etc.

In most cases all the possible reduced acids were also utilised,
including the a^-dihydro-acids, the ^y-dihydro-acids, and the fully
reduced acids, Pt*[CH2]^'C02H.

Menthol and brucine served as the sources of optical activity, and, in
order to obtain an idea of the normal molecular rotatory power of
menthyl esters and brucine salts, use has been made of the principle
laid down by Guye {Compt. rend., 1894, 119, 906), Tschugaeff {Ber.,
1898, 31, 360), and Minguin {BuU. Soc. chim., 1902, [iii], 27, 593)
that the molecular rotation of active derivatives of an homologous
series, such as the normal fatty acids, attains a constant value, and the
mean value of the menthyl esters and brucine salts of acetic to
n-hexoic acid has been adopted as the normal value in each case.

UNSATURATED GROUPS ON OPTICAL ACTIVITY. PART II. 1571

These numbers, deduced from measurements made by the author in
the same solvent (chloroform) and at the same concentrations and
temperature (15°) as the main results, are given in the following
table :

Menthyl ester. Brucine salt.

A A ^

<• ^ e ^

Acid. 5 per cent. 1\ per cent. 5 per cent. 2^ per cent.

Acetic -158-2 -157

Propionic 156-6 157

M- Butyric 161-2 161

71- Valeric 161-9 162

n-Hexoic 164-4 168

0 -258-0 -260-6
2 248-1 252-3
7 247-4 251-2

1 247-4 251-6
1 246-8 252-8

Mean value ... -160 46 -161-22 -249-54 -253-70

It may be pointed out that the menthyl ester values agree well
with those of Tschugaeff i^oc. cit.) measured without solvent, and
those of Rupe {Annalen, 1903, 327, 164) determined in alcoholic
solution.

Experimental.

The three unsaturated acids of the muconic acid group were prepared
from the dimethyl ester of /3y-hydromuconic acid as described by Bode
{Annalen, 1864, 132, 95), Ruhemann (Trans., 1890, 57, 931), and
Baeyer and Rupe (Annalen, 1890, 256, 7). Adipic acid was obtained
by the oxidation of cyclohexamol (Holleman, van der Laar, and Slyper
Eec. trav. chim., 1905, 24, 23).

The ^y-hydro-acids and piperonylbutyric acid were prepared from
sorbic, piperic, and cinnamylidenemalonic acids by reduction with
sodium amalgam, and the ySy-acids were converted into the a/?-iso-
merides by Riiber's method (Ber., 1904, 37, 3120).

I. Menthyl Esters.

The menthyl esters used were prepared, except when otherwise
stated, by acting on the acid with a slight excess of thionyl chloride,
warming on the water-bath, and finally distilling off excess of this
reagent under diminished pressure. The resulting acid chloride was
mixed with rather more than the theoretical amount of menthol, and
heated at 100° for five or six hours. After cooling, the mass was
dissolved in ether and shaken once or twice with dilute sodium
carbonate solution. The ethereal extract was evaporated, and the
ester purified by distillation under diminished pressure or by
recrystallisation.

Dimmthyl Muconate, C^Q^^^'CO^'OW.GB.'GW.G^'CO^'C^^U^y~
This ester separated from methyl alcohol in well defined, tetrahedral
crystals, which possessed the unusually high melting point (for an
ester of menthol) of 168° :

5 L 2

1572 HILDITCH: THE EFFECT OF CONTIGUOUS

0-1719 gave 0-4689 CO^ and 0-1547 H2O. 0 = 74-40; H = 10-00.

C20H40O4 requires 0 = 74-64 ; H= 10-05 per cent.
Dimenthyl ^y-IIydromuconate,

CioHio-CO^-OH^-OHrCH-OH^-OO^-CioHi,.
— In order to eliminate the possibility of any a/8-acid being formed in
consequence of the presence of hydrogen chloride, the ySy-acid was
heated in a sealed tube at 130° with excess of menthol for ten hours.
In this way a rather poor yield of the ester was obtained. After
purification from methyl alcohol, it formed soft, rhombohedral crystals,
readily soluble in the usual organic solvents, and melting at 79° :
0-1328 gave 0-3629 OOg and 0-1238 H2O. 0 = 74-54; H = 10-36.

C26H44O4 requires 0 = 74-30 ; H = 10-48 per cent.
Dimenthyl afi-Hydromuconate,

CioHi9-C02-CH2-CH2-CH:OH-OOo-CioHi9.
• — This ester was obtained in much better yield than either of the fore-
going. It was recrystallised from light petroleum, and then formed
radiating needles, soluble in most of the ordinary solvents, and melting
at 83° :

0-1237 gave 0-3359 CO2 and 0-1137 H2O. 0 = 74-07; H = 10-22.
OafiH^^O^ requires 0 = 74-30 ; H = 10-45 per cent.

Dimenthyl Adipate, OioHj9-002-OH2-OH2-OH2-OH2-C02-OioHi9.
— This ester was prepared from adipic acid (8 grams). Yield
11 grams. The substance crystallised from light petroleum in small,
wax-like needles, melting at 61°:

0-1071 gave 0-2918 OO2 and 0-1040 HgO. 0 = 74-30 ; H = 10-79.
OggH^eO^ requires 0 = 73*92 ; H= 10-90 per cent.

Menthyl Pijjerate, CH2:02:CgH3-OH:OH-OH:CH-002-OioHj9.— This
was obtained in small, colourless needles, melting at 83°. It is readily
soluble in organic media, and was recrystallised from a small amount
of methyl alcohol :

0-1096 gave 0-2984 OOg and 0-0796 H2O. 0 = 74-25 ; H = 8-07.

^22^28^4 requires 0 = 74-16 ; H = 7-86 per cent.
Menthyl fiy-Hydropiperate,

OHglOalCeH.-CHg-CHIOH-CHg-COg'OioHig,
was prepared by heating the acid and menthol alone at about 130° for
a day. The compound was purified by distillation under diminished
pressure, the portion boiling constantly at 263°/25 mm. being taken as
pure. The ester is a readily soluble, pale yellow oil :

0-1552 gave 0-4176 OO2 and 0-1136 HgO. 0 = 73-36; H = 8-13.

O22H3QO4 requires 0 = 73*74 ; H = 8-38 per cent.
Menthyl afi-Uydropiperate,

OH2:02:OeH3-CH2-OH2-OH:CH-C02-CioHi9,

UNSATURATED GROUPS ON OPTICAL ACTIVITY. PART II. 1573

boiled at 270 — 273°/25 mm. It solidifies in a freezing mixture, but
at the ordinary temperature is a colourless oil, which gradually
resinifies in air :

0-1237 gave 0-3348 CO.^ and 0-0916 HjO. C = 73-82 ; H = 8-23.

C20H30O4 requires C = 73-74 ; H = 8'38 per cent.
Menthyl Piperonylhutyrate,

CH9.0o.C(5H3'CIl2*CH[2'C/Il2*CH2'C0.2'CjQti2^.
. — This is best prepared by heating the acid with a slight excess of
menthol at 130° for about fifteen hours, after the reaction mixture has
been saturated in the cold with dry hydrogen chloride. It is a colour-
less oil, not very stable in air, but boiling (practically undecomposed)
at 248—251720 mm. :

0-1402 gave 0-3744 CO, and 0-1148 HgO. C = 7285; H = 9-10.
C22H32O4 requires C- 73-33; H = 8-89 per cent.

II. Brucine Salts.

The rotations of the brucine salts were directly obtained by mixing
exact equivalent amounts of anhydrous brucine and the various acids
in dry chloroform and making up to the required concentration. The
salts were then recovered from the chloroform solution and purified
for analysis and characterisation by recrystallisation from various
solvents.

Dibrucine Muconate, Q^^^(dJ^Q^^r,ff)j^^n,9>1^2^. — Small, hard,
radiating prisms, sparingly soluble in acetone, moderately so in water
or chloroform, and melting indefinitely at 104 — 168° :

0-1228 gave 0-2604 CO2 and 00714 H^O. C = 57-81 ; H = 6-46.

0-1382 lost 0-0183 H2O at 100°. H20 = 13-24.
C52H580i2N4,8H20 requires C = 58-09 ; H = 6-88; H20 = 13-41 percent.

Dibrucine Py-Hydromuconate, Q^^i^O^,{Q<^^^QO^^ofiYi.^O. — White,
cubical crystals, readily soluble in water, and melting to a clear liquid
at 113°:

0-1320 gave 0-2812 CO2 and 0-0848 H2O. C = 58-09; H = 7-14.

0-1887 lost 00244 H2O at 100°. H20 = 12-93.
C52HgoOi2N4,8H20 requires C = 57-98; H = 7-06; H20 = 13-39 per cent.

Dibi'ucine a^-Hydromuconate, G^^O^iGo^ii-^^Pi^ ilii^^^i^- — Small,
white octahedra, slightly soluble in acetone, and moderately so in
chlox'oform, melting at 166° :

0-1482 gave 0-3291 CO2 and 0-0862 H2O. C = 60-54 ; H = 6-46.

0-1854 lost 00179 HgO at 100°. H20 = 9-66.
C52HgoOi2N4,5lH20 requires C = 60-53 ; H = 6-31 ; H2O = 9-60 per cent.

Dibrucine Adipate, Q^-^^OJ^G^^^^O^c^^. — Soft, white tablets,
readily soluble in cold water, and melting and decomposing at 204° :

1574 HILDITCH: THE EFFECT OF CONTIGUOUS

0-1 108 gave 02712 COg and 0-0654 H.O. C = 66-74 ; H = 6-56.
^5''^62^i2^4 requires 0 = 66-82 ; H = 6-64 per cent.

Brucine Ftperate, G.^yTi^QO^fC.^^'ii^QO^'N^,!^^^. — Long, thin, rect-
angular tablets from water, melting at 144°:

0-1576 gave 0-3786 00, and 0-0824 H2O. 0 = 65-52 ; H = 5-81.

0-1959 lost 00085 HoO at 100°. H,0 = 4-34.
CggHgeOgNo.UHaO requires 0 = 65-72 ; H = 6-10 ; H20 = 4-23 per cent.

Brucine Py-Hydropiperate, 0j2H,oO4,023H2g04N'2,3H2O, — Slender,
slightly efflorescent prisms, which crystallise well from water, and
melt at 73° :

0-0914 gave 0-2109 COg and 0-0505 HgO. 0 = 62-92; H = 6-18.
OajHgsOgNo.SHjO requires 0 = 62-87; H = 6-59 per cent.

Brucine a(3- IlydropijJerate, Oj2Hi204,023H2g04N2,4H20. — Quadratic
tablets, melting at 70°, and frothing and evolving water of crystallisa-
tion at 100° :

0-1219 lost 00126 H2O at 100°. H20 = 10-34.

035H3sOgN2,4H20 requires H20 = 10-50 per cent.

Brucine Piperonylhutyrate, Q-^^^-^fi^,Go^'iQ^i^ 2^^\^2^- — ^ij^^, soft
needles, melting at 73^75° to a clear liquid. The salt dried at 100°
was used for analysis :

0-1203 gave 0-2997 OO2 and 0-0686 HgO. 0 = 67-79 ; H = 6-34.

0-1363 lost 0-0160 Rf> at 100°. HgO^ 11-74.
C35H4o08'^2 requires 0 = 68-17 ; H = 6-49 ; 4JH20 = 11-62 per cent.

Brucine Sorhate, OgHg02,023H2Q04N'2,l|H20. — Hard, compact prisms,
melting at 167°:

0-1204 gave 02900 OOg and 0-0768 HgO. 0 = 65-69; H = 7-09.

0-2387 lost 0-0120 H2O at 100°. H2O = 5-03.
029H340gN2,liH20 requires 0 = 65-30 ; H = 6-94 ; H2O = 5-07 per cent.

Brucine Py-Hexenoate, Q^-^^fi.2,G2^2&^^2- — Stout prisms, dark-
ening at 175°, and melting at 183°.

Brucine n-Hexoate, OgHjo02,023H2g04N2,3H20. — Slightly deliques-
cent, cubical crystals, melting at 66° :

0-1186 gave 0-2684 OOg and 0-0808 H2O. 0 = 61-70; H = 7-57.
C29H380gN2,3H20 requires 0 = 61-70; H = 7-80 per cent.

Dibrucine Cinnamylidenemalonate, C^^'H.^ff>^,C^Qfl^oOgl^^,5R2^- — -^
cream-coloured powder, very soluble in water, frothing and decom-
posing at 110° :

0-1808 gave 0-4212 00, and 0-1076 H2O. 0 = 63-52 ; H = 6-62.
OjgHggO, 2^4,5 HgO "requires 0 = 63-49 ; H = 6-57 per cent.

Dibrucine Flienylpropenyhnalonate, Oj2Hj204,04gH520gN4,4H20. — A
mass of soft, cream crystals, melting and frothing at 96 — 99° :

I

UNSATURATED GROUPS ON OPTICAL ACTIVITY. PART II. 1575

0-1634 gave 0-3876 COj and 0-0944 HgO. C = 64-71 ; H = 6-47.

C58Hg^Oi2N4,4H.p requires 0 = 64-45 ; H = 6-67 per cent.
Dihrucine Phenylpropylidenemalonate, CjoHjgO^.C^QHggOgNpSHgO.
— Small, monoclinic prisms, melting at 68°, and evolving water of
crystallisation at 105°:

0-1800 gave 0-4338 CO., and 0-1266 H.p. 0 = 65-73 ; H = 650.
C58Hg^Oi2N4,3H20 requires 0 = 65-54 ; H = 659 per cent.

Polarimetric Results.

The polarimetric measurements were carried out, as in previous
investigations, in chloroform solution in a 2-dcm. tube, and, in the
majority of cases, at two concentrations. The temperature of the
solutions did not vary beyond the limits of 14-5° to 16°.

The brucine was dried to constant weight at 100° in order to
remove water of crystallisation. The rotations before use (5 per cent.
solution in chloroform) were then as follows :

Menthol

Brucine

Wd.

[M]„.

48-84°

-76-2

21-50

478-6

The results obtained are collected in the following tables, which
give, in addition to the specific and molecular rotatory powers, the
difference between the molecular rotation of each compound and the
normal values previously quoted:

I. Menthyl Esters.

(a) Muconic Acid Series :

Percentage concentration.
5. 2i.

[a]„. [M],. Diff. [^. [M]I 5ii\

Dimenthyl muconate — _ _ -93-40° -390-4° 68-0°

aj3-hydromuconate ... -88-80° -372-9° 520° 88-78 372-8 50-4

y37-hydromuconate ... 81-52 842-4 21-5 80-78 339-3 16-9

,, adipate 83-80 353-6 32-7 83-60 352 8 30-4

(b) Piper i^; Acid Series :

Menthyl piperate -53-02° -188-8° 28-3° -52-76° -187-8° 26-6°

aa-hydropiperate 45-92 164-4 3-9 46-08 165-0 3-8

jSy-hydropiperate 4222 151-1 -9-4 4212 150-8-10-4

„ piperonylbutyrate 39-68 142-9-17-6 38-00 136-8-24-4

II. Brucine Salts.

(a) Muconic Acid Series :

Dibrucine muconate -9-52° -88-5° 410-6° -9-/2° -90-4°417-0°

„ oj8-hydromuconate ■. 38-04 354-6 144-5 38-52 359-0 148-4

,, j37-hydromuconaie 38-50 358-8 1403 38-24 356-5 150-9

,, adipate 42-80 399-2 99-9 42-60 397-8 109-6

1576 HILDITCH: THE EFFECT OF CONTIGUOUS

11. Brucine Salts (continued).

(b) Piperic Acid Series :

Percentage concentration.
5. 2i.

[a]„. [M]„. Diff. [a]o. [M]„. Diff.

Brucine piperate -5-02° -;30-7°218-8° -4-68° -28-6°225-r

,, o)8-hvdropiperate 25-10 154-1 95-4 25-12 154-3 99-4

,, j87-hydropiperate 29-08 178-5 71-0 29-16 179-1 74-6

,, piperonylbutyrate 28-26 174-1 75-4 27*68 170-5 83-2

(c) Sorbic Acid Series :

Brucine sorbate -25-50° -130-0" 119-5° -23-84° - 120-6° 133-1°

,, hydrosorbate 44-72 227-2 22-3 42-16 214-2 39-5

,, w-hexoate 48-39 246-8 2-7 49-57 252-8 0-9

(d) Cinnamylidenemalonic Acid Series :

Dibrucine cinnamylidenemalonate — — — -9-84° -98-99° 408*4°

,, o;8-hydrocinnamyli-

denemalonate -44-08° -444-2° 54-9° 43-60 439-5 67-9

,, ySy-hydrocinnamyli-

denemalonate 50-52 509-2-10-1 50-12 505-2 2-2

It should be mentioned that Rupe {loc, cit.), in examining the effect
caused by the proximity of the ethylenic bond to the asymmetric
complex in the isomeric pentenoic, hexenoic, etc., menthyl esters,
prepared menthyl sorbate and found that it possessed a much higher
rotatory power than any of the mono-ethylenic esters, and assumed
that the anomaly was due to the presence of the conjugated ethenoid
system. It will be useful to compare these figures (obtained from
alcohol solution) with the other series now recorded (the "differences"
given are here calculated from Rupe's mean value for the fatty
menthyl esters in alcohol, namely, [M]d= - 164-6°).

[M]d. Difference.

Menthyl sorbate ... -221-3° 56-7°

,, o/3-hexenoate 172-4 7'8

,, /37-hexenoate 164-1 — 0*5

,, n-bexoate 164-7 0-1

It will be noticed that in the series studied by the author, the
compounds containing two contiguous ethenoid groups possess, without
exception, the greatest anomaly in their respective series, whilst in
general the dihydro-acids possess a larger rotation than the fully
saturated members. It should be observed that the effect produced
by a conjugated system is very much better defined than those due to
the a^- or /?-/-ethylenic acids ; the rotatory powers of derivatives of
the latter acids are relatively close to those of the saturated acids, and
the differences between the isomeric a/3- and ^y-acids are usually of
a small order, although, in all the instances examined, the a/3-acid,
the ethylenic linking of which is contiguous to the " unsaturated "

UNSATURATED GROUPS ON OPTICAL ACTIVITY. PART II. 1577

carboxyl group, and also lies nearer to the asymmetric system,
possesses the larger anomaly (compare Rupe, loc. cit.). Finally, the
rule that the saturated derivatives show least anomaly, finds an
exception in the case of dimenthyl adipate, a point which is discussed
in the next paper.

It is interesting, also, to notice the relative anomalies displayed by
the different series studied. Muconic acid, for example, exhibits a
larger anomaly than piperic acid both in menthyl ester and brucine
salt ; this is rather remarkable, in view of the great influence on
optical activity which has been attributed to the phenyl group
by many workers. It is most probably to be explained by the fact
that muconic acid, COoH-CHICH-CHICH-COoH (and its dimenthyl
ester and dibrucine salt), possesses a structure which is symmetrical
with respect to the centre of the conjugated system. The author
has previously remarked (Trans., 1908, 93, 1620) that such a
configuration is apparently favourable to the exhibition of quite
abnormal rotatory power.

Again, the menthyl esters of two of the reduced piperic acids have
values lying below the normal, in spite of the presence in the molecule
of a benzenoid residue, and it must be conceded that, whilst that
nucleus can undoubtedly produce marked effects on optical activity,
numerous cases go to prove that there is a great deal of apparent
irregularity which remains to be cleared up in the behaviour of this
radicle.

In conclusion, emphasis must be laid on the much greater effect
caused by the conjugation of two ethylenic groups than by that of an
ethylenic and a carboxyl group together (as in the a/3-hydro-acids).
This result was to a certain extent to be expected, in view of Rupe's
experience with menthyl sorbate, and of two instances of isomeric
hydrocarbons previously quoted (Part I., this vol., p. 334), namely :
A^''*'®'-^-menthadiene ([M]u + 133"6°, conjugated) and menthene
([M]d + 45-2°, unconjugated) ; phellandrene ([M]d + 82'1°, conjugated)
and carvomenthene ([Mjj, — 2'9°, unconjugated).

The author wishes to express his indebtedness to Professor Knorr,
in whose laboratory this work has been carried out, and to acknow-
ledge the kind assistance of Mr. S. R. Edminson in connexion with
several of the analyses.

University of Jena.

1578 HILDITCH: THE EFFECT OF CONTIGUOUS

CLXXVIII. — The Effect oj Contiguous Unsaturated
Groups on Optical Activity. Part III. The
Normal Series of Fatty Dihctsic Acids.

By Thomas Percy Hilditch (1851 Exhibition Scholar).

Attention was drawn in the preceding communication to the fact
that, whilst the menthyl esters and bracine salts of the saturated acids
therein described possessed rotatory powers which as a rule were not
greater than the " normal " molecular rotation of such esters or salts,
those of adipic acid were found to be well in excess of the normal
value. This exception appeared to be the more interesting, since of
the various series of acids examined, adipic acid approached most nearly
to a normal fatty acid.

In order to throw more light on this point, and also to examine the
general effect of the progressive separation (by methylene groups) of
the contiguous carboxyl groups in oxalic acid, the author has prepared
the series of optically active esters and salts of the acids of this group
from oxalic to sebacic inclusive. No complete series of such deriv-
atives has previously been prepared ; Walden {J. Russ. Phys. Cliem.
Soc, 1898, 30, 767) gives values for the di-^-amyl esters of some of
the acids, but unfortunately does not mention the adipic ester. His
figures, too, were obtained from esters prepared from optically impure
amyl alcohol.

The preparation and properties of the different compounds used in
the investigation will be first described, and thereafter the details of
the polarimetric measurements and the respective anomalies will be
given. It should be emphasised that, in referring the differences to
the mean value of the fatty acid derivatives as a standard, no par-
ticular importance is thereby attached to the use of these acids for this
purpose. Nevertheless, since they are structurally the simplest
organic acids, and since the rotatory power of their optically active
derivatives attains a constant value, they are, in default of anything
better, suitable as a standard of comparison. This method of esti-
mating the anomaly in optical activity appears to the author to be
preferable to the alternative of comparing the molecular rotatory
power to that of the alcohol or alkaloid concerned, since the latter is
usually of quite a different order, and, moreover, the direction of the
change of rotation on esterification of different active alcohols (or salt-
formation of active bases) by any inactive acid whatever is not
always the same, even the sign of the rotation (as with amyl esters)
being sometimes altered.

UNSATURATED GROUPS ON OPTICAL ACTIVITY. PART III. 1579

Experimental.

The menthyl esters were obtained by the thionyl chloride method
described in the preceding paper.

Dimenthyl Oxalate, (C02*CjoH^9)2. — Firm, white octahedra, which
melted at 67° (compare Zelikoff, Ber., 1904, 37, 1374) :

.0-1364 gave 0-3578 COo and 01252 H2O. C = 71-53; H = 10-20.

CojHggO^ requires C = 72-13 ; H = 10-39 per cent.
Dimenthyl Malonate, Hc^iCO^'^i^-^^o- — Seven grams of soft,
slender needles were obtained from 4 grams of acid and 12 grams of
menthol ; the ester crystallises well from methyl alcohol, and melts
at 62°:

0-1446 gave 0-3850 CO, and 0-1326 B.p. 0 = 72-61 ; H = 10-20.

023H^o^4 requires 0 = 72-63 ; H= 10-53 per cent.
Dimenthyl Succinate, OjqH,9'C02'OH2*CH2'C02'OjqHj9. — Odourless,
rhombic crystals, melting at 63° (compare Arth, Ann. Chivi. Phys.,
1886, [vi], 7, 438) :

0-1034 gave 0-2759 OOg and 0-0996 HgO. 0 = 72-76; H= 10-70.

^^'24^42*^4 requires 0 = 73*10 ; H= 10-66 per cent.
Dimenthyl Glutarate,C^QH.-^Q'C02'[C'H2]^'C02'C-^QH.^Q. — This compound
formed a colourless oil, boiling at 240 — 243°/20 mm., which slowly
crystallised to a mass of colourless needles :

0-1260 gave 0-3386 OO2 and 0-1210 H2O. 0 = 73-28; H = 10-68.

O25H44O4 requires 0 = 73-52 ; H = 10-78 per cent.
Dimenthyl Pimelate, OioHj9'002*[OH2]5*002*OjoHjg, is also an oil,
boiling and decomposing at 248 — 252°/20 mm. At first it is almost
colourless, but becomes converted into a brown, resinous substance on
exposure to the air :

0-1357 gave 0-3688 OO2 and 0-1361 H2O. 0 = 74-11; H = 11-14.

O27H48O4 requires 0 = 74*30 ; H = 11-01 per cent.
Dimenthyl Suberate, OjoHj9'002*[OH2]6*002*OjoH,9. — A colourless
oil, boiling at 257 — 259°/20 mm., and solidifying, after remaining
for a long period in the cold, to a mass of crystals, which re-melt
at 38—39° :

0-1076 gave 0-2934 OO2 and 0-1046 HgO. 0 = 74-35 ; H = 10-80.

CggHg^O^ requires 0 = 7466; H=ll-ll per cent.
Dimenthyl Azelate, OjqHj9'002'[OH2]7'C02'CioH^9.— A very viscous
oil, boiling at 254 — 256°/20 mm., and remaining liquid after being
cooled to - 15° for some time :

0-1712 gave 0-4684 OO2 and 0-1676 H2O. 0 = 74-61; H = 10-88.
C29H52O4 requires 0 = 75-01 ; H = 11-20 per cent.

1580 HILDITCH: THE EFFECT OF CONTIGUOUS

Dimenthjl Sebacate, CjoHj()*C02'[CH2]s'C02'CjoHj(,. — This ester is a
viscous liquid, which boils at 256 — 258°/20 mm., and resists all
attempts to solidify it by cooling to - 10° ;

0-1122 gave 0-3100 CO., and 0-1110 HoO. 0 = 75-36; H = 10-99.

C30H54O4 requires 0 = 75-32 ; H= 11-30 per cent.
The brucine salts were, as in the previous work, made up directly
from the constituents in chloroform solution, and then recovered for
characterisation and analysis.

Dibrucine 0xalate,Q.2SL^O^^0^QYi.r^^O^^,iVB.2O. — Small, white, cubical
crystals, not very soluble in cold water, melting and losing water at
140°, then re-solidifying, and finally melting at 202° :

0-0985 gave 0-2161 OOg and 0-0618 H2O. 0 = 59-84 ; H = 6-97.

C4sH5^0i2N4,4|H20"requires 0 = 60-06 ; H = 6-63 per cent.
Dibrucine Malonate, G^fi^,G^^^^^0^^,^15.2^. — Small, hard crystals,
freely soluble in water, melting and losing water at 102° :

0-1788 gave 0-4086 OO2 and 0-1062 H2O. 0 = 62-32 ; H = 6-75.

O^gHggOijN^.SHgO requires 0 = 62-16 ; H = 6-55 per cent.
Dibrucine Glutarate, Q^^O^,G^^^^O^ ^,^^^0. — A white, micro-
crystalline powder, readily soluble in water, melting and decomposing
at 114°:

0-1468 gave 03314 COg and 0-0962 HgO. 0 = 6156 ; H = 7-28.

G^^Yi.^^0^^ ^,^^.^0 requires 0 = 61-70; H = 6-86 per cent.
Dibrucine Fimelate, C^1I^^0^,C^qH ^^0^1^^,4:11.2^. — Very deliquescent
crystals, melting and evolving water of crystallisation at 104° :
0-1240 gave 0-2822 OO2 and 0-0804 H2O. 0 = 6209 ; H = 7-20.
C53H640i2N4,4H20 requires 0 = 62-36 ; H = 7-06 per cent.

Dibrucine Suberate, 08H^4O4,04gH52O8N'4,4^H2O. — Orisp, cream-
coloured crystals, melting sharply at 102° to a clear liquid :

0-1356 gave 0-3082 OO2 and 0-0872 H2O. 0 = 61-98; H = 7-15.
05iHggOi2N4,4|H20 requires C = 62*'-15 ; H = 7-19 per cent.

Dibrucine Azelate, QQH-^^^0^,(^^^r^cf)^^,'i^2^. — Large, white, fibrous
prisms, soluble in water, and melting at 96° :

0-1116 gave 0-2616 CO2 and 0-0728 H2O. 0 = 63-92; H=7-25.
^bb^of>\2^v^^2^ requires 0 = 64-07; H = 7-19 per cent.

Dibrucine Sebacate, C^^K-^^O^jC^^^^^^^. — Small, white, crystalline
flakes from concentrated aqueous solutions, melting at 112° :

0-1296 gave 0-3234 OOg and 0-0870 H2O. 0 = 68-03; H = 7-46.
05gH-oOi2N4 requires 0 = 67-89 ; H = 7-07 per cent.

The results of the polarimetric measurements (carried out as usual
in dry chloroform solution at 15°) are collected in the following
tables :

UNSATURATED GROUPS ON OPTICAL ACTIVITY. PART HI. 1581

I. Menthyl Esters.

Percentage concentration.

2i.

[a]„.

[M]„.

Diir.

[a]..

[M].,.

Diir.

Diinenthyl oxalate ...

-104-00°

-380-6"

57-7°

-103-40°

-378-4°

56-0''

maloiiate...

79-24

301-]

-19-8

79-54

302-6

-19-8

succinate...

81-90

322-7

1-8

82-40

324-6

2-2

glutarate...

80-26

328-3

7-4

80-16

327-1

4-7

adij)ato ...

83-80

353-6

32-7

83-60

352-8

30-4

pimelate ...

78-31

341-5

20-6

77-82

339-3

16-9

suberate ...

73-56

331-1

10-2

73-28

329-8

7-4

azelate

72-68

337-2

16-3

72-32

335-5

13-1

sebacatc ...

67-08

320-6

-0-3

66-72

318-8

-3-6

II.

Brucine Sails.

Dibnicine oxalate ..

-3-00°

-26-3"'

472-8°

-2-80°

-24-6°

482-8°

maloiiate .

52-76

470-6

28-5

52-76

470-6

36-8

succinate .

65-30

591-6

-72-5

64-12

580-9

-73-5

glutarate .

50-62

465-8

33-3

50-48

464-4

43-0

adijiate ...

42-80

399-2

99-9

42-60

397-8

109-6

pimelate .

42-74

405-2

93-9

44-08

417-9

89-5

suberate..

45-70

439-6

59-5

47-56

457-5

49-9

azelate ...

45-16

440-8

58-3

45-52

444-2

63-2

sebacate ..

48-24

477-5

21-6

48-44

479-5

27-9

There are several points to which attention may be drawn with
respect to these results. In the first place, the two series of results
are approximately parallel, and this must be taken to signify that the
changes produced in the activity of the asymmetric atoms in the
compounds are due to the constitution of the acid part of the
molecule.

Again, oxalic acid exhibits by far the greatest anomaly in both
series, as might be expected from the contiguity in its molecule of two
carboxyl groups rich in residual affinity. But if the anomalies of
brucine and menthyl oxalates be compared with those occurring in the
case of acids containing a conjugated ethenoid system (see previous
paper), it will be found that, with the exception of muconic acid, none
of these compounds exhibit such a marked effect as oxalic acid,
although the " unsaturation " in the latter compound might be ex-
pected to be far weaker than that of two adjacent ethylenic groups.
It seems likely, however, that, as with muconic acid and other com-
pounds {loc. cit.), the symmetrical disposition of the molecule about
the centre of the conjugated system is in some way the cause of the
enhanced optical activity.

For the rest, from analogy to the normal fatty monobasic acids, one
would have expected on first thoughts to see the molecular rotatory
powers decreasing, rapidly at first, to an ultimately fairly constant

1582 HILDITCH: OPTICAL ACTIVITY. PART III.

value, but, as a matter of fact, the series found are very far from
regular.

There is, first of all, a pronounced depression between the first and
fourth member of the series, while the fifth (adipic acid) presents a
second maximum point on the graph. After this point the molecular
rotatory powers seem to become more regular, and may possibly show
to a small extent an alternation similar to that noticeable in the
melting points of the free acids, but no definite information can be
given regarding the ultimate shape of the anomaly curve, since a
sufficient number of the higher members of the series has not been
examined.

The two most noteworthy points are thus the depression in the
second and third, and the exaltation in the fifth members of the
series. "With reference to the former, it is difficult to conceive of any
explanation based on the constitution of the acids. It can only be
said that the rotatory powers of dimethyl malonate and of dibrucine
succinate are markedly lower than the normal value, and that a
similar effect is to be seen in Walden's figures for di-^amyl malonate
{loc. cit.). Indeed, it would appear from the fragmentary evidence
available that the amyl ester curve for these acids closely resembles
that for the menthyl esters. It may be mentioned here that an ex-
ceptionally large temperature-coefficient was observed in the case of
dibrucine succinate.

The exaltation in the adipic compounds admits, on the other hand,
of a possible simple explanation. It finds a parallel in the simple fatty
acid series, in which E,upe {Annalen, 1903, 327, 166) pointed out that
an ethylenic or phenyl group in the S-position with respect to the
carboxy) group sometimes exercises a weakening effect on the rotatory
power. It is obvious that the direction of the effect in not the same
in both cases, but evidently optical activity is influenced by two
unsaturated groups separated by a chain of four carbon atoms.

The exceptional chemical activity of different groups in this position
is well known, and may be recalled by the ease with which water is
eliminated from many dihydroxylic compounds of this type, yielding
lactones or anhydrides :

•CH-CO-OH -CH-CO

•CH-CO-OH ~^ -CH-CO^

The same steric hypothesis which presupposes the contiguity in
space of the hydroxyl groups in such cases would necessitate the carboxyl
groups as a whole being close to each other in adipic acid,

CHg-CHg-COgH

CHg-CHa'COgH'

and it may therefore be that the same influence which causes the

WREN: SOME DERIVATIVES OF L-BENZOIN. 1583

large anomaly in oxalic acid derivatives causes the enhanced rotatory-
power here, namely, the conjunction of two unsaturated groups. The
effect is not unnaturally much less than that observed when the two
conjugated systems are chemically united, and this would account for
its non-appearance in other physical properties less susceptible to
constitutive changes than optical activity.

In conclusion, the author wishes to express his great indebtedness
to As.sistant Prof. Smiles for criticising the work described in this and
the preceding paper, the cost of which has been partly met by a grant
from the Research Fund of the Chemical Society.

Ukivkksity of Jena.

CLXXIX. — Soma Derivatives of \-Benzoin.

By Henry Wren.

The preparation of ^benzoin by the action of magnesium phenyl
bromide on ^mandelamide has already been described (McKenzie and
Wren, Trans., 1908, 93, 310). Since this compound is the first
example of an optically active ketol of simple structure, it was con-
sidered of interest to make a further study of it and some of its
derivatives, and also to prepare its enantiomorphous isomeride. The
work carried out in this direction is described in this and the following
paper.

Experimental.

Preparation of d-£enzoin.

Methyl d-mandelate (25 grams) was converted into d-mandelamide,
CgH5'CH(OH)'CO'NH2, by the method previously described {loc. cit.)
for the preparation of ^mandelamide from methyl Z-mandelate. The
yield amounted to 13 grams :

0-1756 gave 0-4096 CO2 and 0-0928 HjO. C = 63-6; H = 5-9.

0-1886 „ 14-9 c.c. N2 at 12° and 771 mm. N = 9-6.

CgHgOaN requires C = 63*6 ; H = 60 ; N = 9-3 per cent.

This amide resembles its enantiomorphous isomeride in appearance,
melting point (122 — 122-5°), solubility, and specific rotation. The
latter was determined in acetone solution :

l = i, c= 1-6496, al +4-93°, [a]l 4-74-7°.

The value previously found for ^mandelamide under similar con-
ditions was - 73-1°.

1584 WREN: SOME DERIVATIVES OF L-BENZOIN.

d-Benzoin, C,jH5*CH(OH)*CO'CgH5, obtained from cZ-mandelamide
and magnesium phenyl bromide, crystallises from methyl alcohol in
colourless needles, and has the same melting point as ^-benzoin
(131—132-5°):

0-1156 gave 0-3342 CO2 and 0-0588 H2O. C = 78-8; H = 5-7.
Cj^HjoO. requires C = 79-2 ; H = 5-7 per cent.

Its specific rotation was determined in acetone solution :
Z = 4, c = 0-4128, a'r +1-99°, [a]T' +120-5°.

Z-Benzoin dissolved in acetone has [af^'' - 1186° for c = 0-9232.

fZ-Benzoin was converted into benzil (m. p. 95 — 96°) by the action
of concentrated nitric acid.

Methylation of l-Benzoin.

For the methylation of Z-benzoin, Purdie's silver oxide method of
alkylation was employed (compare Lander, Trans., 1900, 77, 734;
Irvine and Weir, Trans., 1907, 91, 1391), as being less likely than
any of the other methods to give a partly racemised product. It
was also used in preference to the hydrochloric acid method by means
of which r-benzoin was methylated (Fischer, Be}'., 1893, 26, 2412),
since it has been shown (Irvine and Weir, loc. cit. ; Irvine and
McNicoll, Trans., 1908, 93, 952) that in the latter reaction the forma-
tion of r-benzoin methyl ether is accompanied by that of a/3-dibenzoyl-
a-methoxydibenzyl and 2-hydroxy-3 : 5-dimethoxytetraphenyltetrahydro-
furan.

Dry silver oxide (21 grams, 2-7 mols.) was added to a solution of
Z-benzoin (7-3 grams, 1 mol.) and methyl iodide (43-9 grams, 9 mols.)
in acetone (100 c.c). On warming, gentle boiling set in, which lasted
about ten minutes. The mixture was subsequently boiled gently with
frequent shaking during two hours, after which time the precipitate of
silver oxide and silver iodide was filtered and well washed with
acetone. The residue, obtained after removal of the acetone, solidified
readily to a mass of yellow crystals weighing 6-9 grams.

The crude Z-benzoin methyl ether was purified by being crystallised
from light petroleum until the value of its specific rotation in chloro-
form solution was constant.

\-Benzoin methyl ether, C^H5'CH(0Me)*C0*CgIIj, separates from
boiling light petroleum in well-defined, rectangular prisms, melting at
53—54°:

0-1272 gave 0-3717 CO2 and 0-0713 H2O. C = 79-69; H = 6-27.
CisHj^Og requires C - 79-62 ; H = 6-24 per cent.

It is readily soluble in the ordinary organic solvents with the excep-
tion of cold light petroleum, in which it is very sparingly soluble.

WREN: SOME DERIVATIVES OP L-BENZOlN. 1585

Its specific rotation in chloroform solution was as follows :
^ = 4, c = 2-1108, al; -7-45°, [a]!; -88-2°.

Its specific rotation was also determined in solution in heptane,
benzene, and ethyl alcohol respectively. lu heptane solution :
^ = 4, c = 0-5648, a}]' +3-34°, [a]l^* +147-8°.

The heptane was optically inactive. It was obtained by fraction-
ating Kahlbaum's heptane, and boiled at 97 — 98°. In ethyl-alcoholic
solution :

l = i,c = 0-5860, a'^ - 2-21°, [aJU - 94-3°.

In benzene solution :

1 = 4:, c = 0-6428, a}-' +1-31°, [aji? +50-9°.

The ^benzoin methyl ether was recovered unchanged from each of
the above solutions.

It is thus apparent that /-benzoin methyl ether is strongly dextro-
rotatory when dissolved in heptane or benzene, whilst it is strongly
Isevorotatory in chloroform or ethyl-alcoholic solution. Similar
alteration in the sign of rotation with variation of solvent has been
observed with a few non-ionised substances. Thus, dimethyl ci-tartrate
is dextrorotatory when dissolved in acetone, methyl alcohol, or aceto-
nitrile, lasvorotatory when dissolved in benzene or chloroform, whilst in
ethyl acetate the sign of rotation varies with the temperature
(Walden, Ber., 1905, 38, 385). Similarly, dimethyl /-malate is
Isevorotatory when dissolved in acetone, methyl alcohol, or ethyl
acetate, but dextrorotatory in chloroform. In benzene solution the
sign of rotation depends on the temperature and concentration
(Walden, loc. cit.). Similar observations have been made by Freundler
(Compt. rend., 1893, 117, 556; An7i. Chim. Phys., 1895, [vii], 4, 244)
in the cases of the normal propyl esters of diacetyl-c?-tartaric acid,
dibutyryl-fZ-tartaric acid, and dihexoyl-cZ-tartaric acid, but in no case
are the variations so marked as in that of /-benzoin methyl ether.

Acetyl-\-henzoin.

^-Benzoin (1*6 grams) was warmed with acetyl chloride (3 grams).
Solution of the benzoin was complete at 35°. The temperature of the
mixture was maintained at 40 — 50° during one hour, after which
it was gradually raised to 100° and maintained at this point until
evolution of hydrogen chloride ceased. Excess of acetyl chloride was
removed by allowing the pi'oduct to remain under diminished pressure
over soda-lime.

Acetyl-\-henzoin, C6H5-CH(0-CO-CH3)-CO-C6H5, separates from boil-
ing light petroleum in colourless needles, sometimes grouped in
rosettes. It is readily soluble in hot light petroleum, and in cold

VOL. XCV. 5 M

1586 WREN: SOME DERIVATIVES OF L-BENZOIN.

ether, methyl and ethyl alcohols, acetone, chloroform, benzene, or
glacial acetic acid. In cold light petroleum it is sparingly soluble :
0-1204 gave 0-3316 COg and 0-0612 U^O. 0 = 75-1 ; H = 5-7.

C^gHj^Og requires 0 = 75-5 ; H = 5-6 per cent.
The specific rotation of successive crops from light petroleum was
determined in chloroform solution :

Z=4, c = 1-0116, al,' -8-81°, [af^ -217-7°.
l=i, c = 0-7240, a]^' -6-31°, [a]'^' -217-9°.

Carbanilido'l'benzoin.

A. mixture of Z-benzoin (2 grams) and phenylcax'bimide (3 grams)
was heated on the boiling-water bath during thirty minutes. The
benzoin rapidly dissolved to a somewhat brown solution, which
partly solidified on cooling. The excess of phenylcarbimide was
removed by means of light petroleum, and the solid residue, consisting
of carbanilido-^benzoin together with small quantities of carbanilido-
r-benzoin and diphenylcarbamide, was triturated with a small quantity
of cold ethyl acetate, in which diphenylcarbamide is insoluble. After
filtration and removal of ethyl acetate from the filtrate, the crude
carbanilido-Z-benzoin was purified by recrystallisation from methyl
alcohol, and finally from liiiht petroleum (b. p. 60 — 80°).

Carhanilido-\-henzoin, C6H5-CH(O-0O-NH-C6H5)-CO-06H5, separ-
ates from boiling light petroleum, in which it is sparingly soluble, in
rather ill-defined, colourless crystals. It dissolves readily in cold
benzene, ethyl alcohol, acetone, ether, chloroform, ethyl acetate, or
pyridine. It is moderately soluble in cold methyl alcohol, readily so
in the boiling solvent. It melts at 121-5° to a clear liquid, which,
when heated through a further 2° or 3°, again solidifies, re-melting at
163-5°. The letter temperature agrees with the melting point (163°)
given by Gumpert [J. pr. Chem., 1885, [ii], 32, 280) for carbanilido-
r-benzoin :

0-1499 gave 0-4201 CO2 and 0-0726 HgO. 0 = 76-4 ; H = 5-4.
OgiH^yOgN requires 0 = 76-1 ; H = 5-2 per cent.

For the determination of the specific rotation in benzene solution,
successive crops from light petroleum were dried in a vacuum over
paraffin wax until constant in weight :

Z = 4, c = 0-8228, aT -9-57°, [aj^ -290-8°.
Z=4, c = 0-8024, o}^ -9-37°, [a.]'^ -291-9°.

The specific rotation was also determined in acetone solution :
Z= 4, c = 0-6528, ai] -5-61°, [a]D -214-8°.

WREN: SOME DERIVATIVES OF L-BENZOIN. 1587

Interaction of \-Benzoin and Hydroxylamine.

The study of the interaction of hydroxylamine and ^-benzoin was of
particular interest, owing to the mutarotation of the a-oxime which
was observed in various solvents.

\-Benzoin-a-oxiine.

■ A mixture of ^-benzoin (5'6 grams) and ethyl alcohol (22-4 c.c), to
which had been added solutions of hydroxylamine hydrochloride
(4*5 grams in 5"6 c.c. water) and sodium hydroxide (25 grams in
6*8 c.c. water), was heated for one hour on the boiling-water bath,
and, after cooling, poured into water (200 c.c). A bulky, white
precipitate (5'1 grams) separated, from which, after two recrystal-
lisations from benzene, ^-benzoin-a-oxime (2 grams) was obtained as
a white, amorphous powder, which melted at 163"5 — 164'5°:

0-1273 gave 0-3432 CO2 and 00661 HgO. C = 73-5 ; H = 5-8.
0-1327 „ 7-2 c.c. N2 at 15° and 751 mm. ]Sr=6-4.

Cj^H^gOaN requires C = 74-0; H = 5-8; N=6-2 per cent.

\-Benzoin-aoxime is moderately soluble in boiling benzene, very
sparingly in the cold solvent. Its specific rotation was determined
in a number of solvents.

In chloroform solution :

^ = 4, c- 0-8576, ai,^ -0-11°, [a]i,' -3-2°

This value did not change during twenty-one hours. After i-emoval
of the solvent at the ordinary temperature, the residue melted at
163-5—164°.

In ethyl-alcoholic solution :

;=4, c = 0-9648, a^ 4-0-17° [a]i? 4-4-4°.

During twenty-two hours the activity of the solution remained
constant. The residue, after removal of alcohol, melted at
163—163-5°.

In ethyl benzoate solution :

Z = 4, c = 0-4724, a^ 4-0-70°, [aJT 4-37-0°.

This solution showed no change in activity daring nineteen hours.

In acetone solution :

Expt. 1.-1 = 4:, c = 0-7068, a'^ 4-0-51°, [a]};' 4-18-0°.

The polarimetric determination was performed immediately after the
solution was made up. The solution was allowed to evaporate in an
open dish at the ordinary temperature. The residue, after being dried
in a vacuum, melted at 162-5°.

Bxpt. II,— I = 4, c = 1 -6892.

5 M 2

1588

WREN: SOME DERIVATIVES

OF L-BENZOIN.

In this

experiment

mutarotation

was observed.

Time in hours

«"°-

MT-

Time

in hours.

<'°-

[<'■

2-25

+ 2-15°

+ 31-8°

22-8 +

10 •2-2°

+ 151-2°

3-25

3-31

49-0

27-5

9-97

147-5

5-33

6-43

95-1

29-8

9-87

146-1

7-33

8-36

123-7

47-0

9-56

141-5

8-33

8-92

132-0

56-3

9-50

140-6

9-33

9-35

138-3

95-0

9-37

138-6

10-33

9-72

143-8

On evaporation, the solution left a viscous residue.
Expt. in.—l=i, c = 0-9803, « = 23- 7 ±0-2°.

Time in hours.

Od.

[«]«■

0-75

+ 0-92°

+ 23-5'

1-25

1-71

43-6

1-75

2-16

55-1

2-25

4-12

105-0

2-75

4-45

113-4

3-25

4-69

119-5

3-75

4-84

123-4

Time in hours.

Uo.

[«]u.

4-75

+ 5-17°

+ 131-8

5-75

5-37

136-9

6-75

5-47

139-4

7-75

5-48

139-7

8-75

5-44

138-6

23-25

5-42

138-1

Expt. IV. — Solvent : Acetone to which one drop of piperidine per
5 c.c. solvent had been added :

Z = 4, c = 1-034, aii'- +0-75°, [aJT +18-P.
The activity of this solution remained constant during twenty
hours. After removal of the solvent, the residue melted at
150—159°.

The a-oxime exhibited mutarotation in acetophenone solution :
l = i, c = 0-8928, « = 23-5 ±0-3°.

Time in hours.

Od.

[«]..

0-5

+ 1 -84°

+ 51-5

0-75

1-79

50-1

1-25

1-79

50-1

2-75

1-98

55-4

3-75

2-28

63-5

4-75

2-45

68-6

Time in hours.

O-D.

[«]d.

5-75

+ 2 70°

+ 75-6

6-75

2-83

79-2

7-5

2-87

80 3

25-0

3-61

101-1

25-5

3-64

101-9

In benzaldehyde solution :

Z = 4, c = 0-8552, < = 23-8 ±0-1°.

Time in hours.

o-v

[a]..

Time in hours.

Od.

[a]D.

0-25

+ 0-91°

+ 26-6='

4-25

+ 0-99°

+ 28-9

1-25

0-91

26-6

5-25

1-06

30-9

2-25

0-96

28-1

23-5 (« = 18°)

1-61

47-1

3-25

0-98

28-6

In methyl ethyl ketone solution :

^=4, c = 2-1364, aT +2-11°, [a]r +24-7°.

The value of a^^ remained absolutely constant during three and
a-quarter hours. After forty-six hours it had only increased to 2-28°.
The residue, after removal of the solvent, melted rather indefinitely at
153—158°.

WREN: SOME DERIVATIVES OF L-BENZOIN. 1589

Mutarotation of ^-benzoin-a-oxime was thus observed in acetone,
acetophenone, benzaldehyde, and methyl ethyl ketone solution, whilst no
mutarotation was observed with chloroform, ethyl alcohol, and ethyl
benzoate. In this connexion it is interesting to note that Lowry
(Trans., 1899, 75, 219) has shown that the equilibrium between nitro-
camphor and i//-nitroc.imphor is attained far more rapidly in acetone
than in any other solvent, under similar conditions of temperature and
concentration. It therefore seems possible that mutarotation in the
case of non-ketonic or -aldehydic solvents was not ol)served, since the
velocity of change in these media is extremely small. Even in aldehydic
and ketonic solvents some external impulse appears to be necessary to
start the change. Thus, in one case /-benzoin-a-oxime was recovered
practically unchanged from acetone solution. Further, a solution of
the substance in benzaldehyde was kept in the polarimeter tube for two
and a-quarter hours before change commenced, whilst a solution in
acetophenone showed no change during about two hours, at the end of
which period reaction started and then proceeded in the usual manner.

Lowry (Trans., 1899, 75, 221 ; 1903, 83, 317) and Lowry and
Magson (Trans., 1908, 93, 107) have shown the striking effects of
traces of various catalysts on solutions of (Z-glucose and nitrocamphor
in different solvents. Some such catalytic influence seems also to come
into play in the case of ^benzoin-a-oxime. Up to the present it has
not been possible to identify the catalyst. The influence of piperidine
on the change in acetone solution was investigated, and found to be
inhibitive. It seems most probable that ^benzoin-a-oxime, when
dissolved in ketonic or aldehydic solvents, gradually passes into the
isomeric /8-oxime. Unfortunately, no pure substance could be isolated
from the viscous residues which were obtained on evaporating solutions
in which mutarotation had taken place, nor could pure Z-benzoin-/?-
oxime be isolated. Evidence has, however, been obtained to show that
the latter is strongly dextrorotatory.

To test the relationship between ^-benzoin-a-oxime and ^-benzoin, the
former was treated according to the method given by Lapworth (Trans.,
1907, 91, 1133) for the decomposition of camphoroxime.

^-Benzoin-a-oxime (0*9 gram) was warmed with a solution of form-
aldehyde (20 c.c.) and concentrated hydrochloric acid (15 c.c). The
oxime rapidly passed into solution, from which a white precipitate
soon began to separate. After warming for twenty-five minutes, the
reaction mixture was poured into water. The precipitate which
separated was identified as ^-benzoin by its melting point and rotation.
No "Walden invei'sion was thus detected.

1590 WREN: SOME DERIVATIVES OF L-BENZOIN.

Interaction of \-Benzoin-a-oxime and Concentrated Sulphuric Acid.

The configuration of the a- and yS-oximes of r-benzoin has been
studied more particuhirly by Werner and Detscheff [B&r., 1905, 38,
73), Werner and Piguet {Ber., 1904, 37, 4295), and E. Fischer and
Hiitz {Ber., 1895, 28, 585). The latter investigators showed that the
a-oxime is converted in good yield into a-phenylindoxyl by the action
of cold concentrated sulphuric acid. Since a rather impure specimen
of r-benzoin-/3-oxime under the same conditions gave only a small
amount of a-phenylindoxyl, the formation of which was probably
attributable to the r-benzoin-a-oxime present, it follows that the latter
contains the 'OH and •CH(0H)'CgH5 groups in the cis-position. Its
transformation into a-phenylindoxyl may then be represented by the
equation :

CeH,.C.CH(OH)-C,H, ^ CeH,-C=C-OH

N-OH HN— CgH^ ^

Werner and Detscheff (J,oc. cit.) have shown that pure r-benzoin-^S-
oxime does not yield a-phenylindoxyl when acted on by sulphuric
acid.

The action of concentrated sulphuric acid on ?-benzoin-a-oxime was
carried out in accordance with the directions given by Fischer and
Hiitz (loc. cit.). Yellow needles were obtained which showed all the
reactions of a-phenylindoxyl. They melted at 170 '5 — 171°, gas evolu-
tion and decomposition occurring at a slightly higher temperature.
When mixed with an approximately equal quantity of a-phenylindoxyl,
prepared from pure r-benzoin-a-oxime, the melting point was prac-
tically unchanged (170'5°) with the same phenomena as previously
noticed. Fischer and Hiitz quote " about 175°" as the melting point
of a-phenylindoxyl. It follows then that, if the Hantzsch- Werner
interpretation of the isomerism of oximes is accepted, the configuration

aH,-CH(OH)-C-C6H5
of tbenzoin-a-oximemustbe : ^..^ ''

HO*N

Attempted Isolation of \-Benzoin-/3-oxime.

In the preparation of Z-benzoin-a-oxime it was noticed that consider-
able loss occurred when the crude oxime was purified by recrystal-
lisation from benzene. The benzene mother liquors were therefore
evaporated to dryness in a vacuum, when a pasty mass, mixed with a
few solid particles, remained, which did not solidify further when kept
in a vacuum during several weeks. It was mixed with a small quantity
of ether, and the solution so obtained filtered from the small quantity
of undissolved Z-benzoin-a-oxime. When the ethereal filtrate was

WREN: SOME DERIVATIVES OF L-BENZOIX. 1591

again evaporated in a vacuum, a pasty mass again resulted, which
dissolved in practically all organic solvents, and could not be obtained
from them in a crystalline state. By dissolving the mass in warm
carbon tetrachloride and cautiously adding light petroleum, a small
amount of solid was precipitated, which, after drying, melted
indefinitely at 136 — 154°. Its specific rotation was determined in
ethyl-alcoholic solution :

1 = 2, c = 0-896, oo +1-18°, [a]„ +65-8°.

^Benzoin-a-oxime has [aj^ + 4-4° in ethyl-alcoholic solution. Since
"Werner and Detscheff {loc. cit.) have shown that the production of
racemic yS-oxime always accompanies that of the racemic a-oxime, it
appears valid to conclude that the above compound was crude
Z-benzoin-)8-oxime. The amount of material was too small to allow
further purification.

An attempt was then made to prepare ^benzoin-y8-oxime directly,
according to the directions given by Werner and Detscheff {loc. cit.)
for the preparation of r-benzoin-^-oxime.

^Benzoin (2 grams) was covered with a mixture of ethyl alcohol
(8 grams) and water (12 grams). To this a solution of hydroxyl-
amine hydrochloride (0'9 gram in 2 c.c. of water), mixed with 10"4 c.c.
of 2'5iy-sodium hydroxide solution, was added. The mixture was
warmed in the water-bath at 50 — GO'^ with brisk shaking until, after
eighteen minutes, all the benzoin had passed into solution. After
cooling, the mixture was poured into water, and the oxime liberated by
carbon dioxide and extracted with ether. After drying the ettiereal
solution and removing the ether, a pasty mass remained which did not
solidify completely. It was redissolved in dry ether, and, on allowing
the ethereal solution to evaporate gradually, two small crops of crystals
were obtained, which melted at 151 — 152° and 149 — 150^ respec-
tively. When united and examined in acetone solution, they were
found to be optically inactive, and therefore consisted of r-benzoin-a-
oxime. The ethereal solution, from which the crops had been re-
moved, was strongly dextrorotatory. The whole solution, examined in
a 1-dcm. tube, had a^ -H 6-66°. Further efforts to obtain a solid oxime
from it were fruitless, viscous products being invariably obtained which
could not be caused to crystallise.

Interaction of \-Benzoin and Semicarhazide Hydrochloride.

Biltz {Annalen, 1905, 339, 257) has described the preparation of
r-benzoinsemicarbazone by the interaction of an alcoholic suspension
of r-benzoin and an aqueous solution of semicarhazide hydrochloride.
An attempt was made to prepare Z-benzoinsemicarbazone by the same
method;

1502 WREN: SOME DERIVATIVES OF L-BENZOIN.

^Benzoin (2 grams) was dissolved in boiling ethyl alcohol (47 c.c.)
and the solution rapidly cooled to the ordinary temperature, where-
upon a portion of the benzoin separated. After the addition of a
solution of semicarbazide hydrochloride (1 gram) in water (3 c.c), the
mixture was shaken in a thermostat at 25° during five days. The
clear yellow solution so formed was evaporated to dryness in a vacuum,
and the residue washed with water and recrystallised from aqueous
alcohol. The crystals so obtained melted at 129 — 131°, and proved to
be slightly racemised ^-benzoin ;

0-1284 gave 0-3716 COj and 00667 HgO. C = 78-9; H = 5-8.
C^^HjgOg requires 0 = 792 ; H = 5-7 per cent.
Z = 2, c = 1-1295, ao -2-39°, [aju -105-8°.

Preparation of Phenylacetylcarhinol.

It was hoped that a series of optically active ketols, of the general
formula CgH5*CH(0H)'C0"R, might be obtained by the action of
Grignard's reagent on Z-mandelamide. As a preliminary experiment,
the reaction of r-mandelamide with magnesium methyl iodide was
investigated, when phenylacetylcarhinol was obtained in small yield.
This ketol is a liquid. Assuming that the active isomeride is also a
liquid, it would be difficult to prove that it contained none of the
inactive variety, if prepared by this method. This line of work was
therefore abandoned for the present.

r-Mandelamide (20 grpms) was gradually added, within an interval
of twenty-five minutes, to a well-cooled solution of the Grignard
reagent prepared from magnesium (18-8 grams), methyl iodide
(111-2 grams), and ether (250 c.c). "When all the amide had been
added, the reaction mixture was gently boiled during eight and a-half
hours, after which it was decomposed by ice and sulphuric acid in the
usual manner. The liberated phenylacetylcarhinol was extracted with
ether and obtained as a pale yellow oil (3 5 grams), which boiled at
138— 140°/23 mm. :

0-1578 gave 0-4140 COg and 0-0966 H^. 0 = 71-6; H = 6-8.
OgHj^Og requires 0 = 72-0 ; H = 6*7 per cent.

Phenylacetylcarhinol, C6H5-CH(OH)-00-OH3, unlike methylacetyl-
carbinol described by Diels and Stephan {Ber., 1907, 40, 4338), does
not solidify when placed in a freezing mixture, when preserved
during several months, or when brought into contact with metallic
zinc. It is insoluble in water, but readily miscible with organic
solvents. It reduces Fehling's solution, alkaline permanganate, and
ammoniacal silver solution in the cold. In alcoholic aqueous solution
it gives no coloration with ferric chloride.

Carapelle {Gazzetta, 1903, 33, [ii], 263) has prepared the same sub-

WREN: RACEMISATION PHENOMENA. 1593

stance from benzyl methyl ketone. He gives the boiling point as
135740 mm.

Phenylacetylcarhinolsemicarhazone separates from boiling toluene as
a white, amorphous powder, and molts at 194*^. It is sparingly soluble
in boiling toluene, benzene, ether, chloi'oform, or acetone, moderately
so in boiling methyl or ethyl alcohol, and readily so in boiling glacial
acetic acid :

0-1589 gave OSSGO COj and 0-0905 H.A C = 57-7; H = 6-4.

0-1508 „ 26-3 CO. Ng at 18° and 760 mm. N = 20-5.

C10H13O2N3 requires C = 58-0 ; H = 6-3 ; N = 20-3 per cent.

The author desires to express his indebtedness to the Research Fund
Committee of the Chemical Society for a grant, which has defrayed
a portion of the expense of this research.

BiRKBECK College,
London, E.G.

CLXXX. — Racemisation Phenomena observed in the
Study of \-Be7izoin and its Derivatives.

By Henry Wren.

In a recent paper entitled "Studien iiber katalytische Razemisierung,"
"Winther (Zeitsch. jjhysikal. Chem., 1906, 56, 465) has divided the
known cases of racemisation — which is defined as the transformation
of an optically active substance into an isomeric inactive substance —
into four classes : (1) autoracemisation, (2) racemisation by heat, (3)
racemisation due to the catalytic action of water or bases, and (4) racemi-
sation due to other catalysts, for instance, hydrochloric acid, sulphuric
acid, and aluminium chloride. In close connexion with this phenomenon
are those cases in which optical activity is wholly or partly lost during
the conversion of an optically active substance into one of its
derivatives.

During a study of the derivatives of ^benzoin, frequent instances of
racemisation have been encountered. ^Benzoin ethyl ether is partly, and
carbanilido-/-benzoin completely, racemised under the action of heat.
Z-Benzoin and its methyl ether are completely and rapidly racemised
by the action of alcoholic potash or sodium ethoxide. Further, methyl
Z-mandelate undergoes partial racemisation during conversion into
Z-raandelamide by the action of cold ethyl-alcoholic ammonia, whilst
under the action of benzoyl chloride at a rather high temperature, of
aniline at 100", and of a saturated solution of hydrogen chloride iA

1 594 WREN : RACEMISATION PHENOMENA OBSERVED IN THE

ethyl alcohol at a temperature not exceeding 40°, ^benzoin is converted
into derivatives of inactive benzoin. Lastly, ^-benzoin-a-oxime under-
goes partial racemisation when acetylated by means of acetic anhydride.
The racemisation of ^-benzoin and of its methyl ether by alkali is of
special interest, since it is probably attributable to keto-enolic change.
Such a possibility in the case of r-benzoin has been indicated by
several investigators. Thus Graebe {Ber., 1898, 31, 2975) showed
that benzoin, under the influence of sulphuric acid, condenses with
gallic acid to form benzoin-yellow. The assumption is made that
benzoin is first converted into w-dihydroxystilbene, thus :

CeH,-CH(OH)-CO-CeH, — C,H,-C(OH):C(OH)-C6H5,
which then reacts in accordance with the equation :

CPh-OH ^^ CPh-0

OH

•C-OH + ( >0H = SH^O + / 1-C— f >0H
CO,hI JOH I j-CO'[ JOH

Similarly, Haworth (Trans., 1909, 95, 486) has shown that benzoin
condenses with the sodium derivative of ethyl cyanoacetate, forming
a8-dicyano-/3y-diphenyl-AP-butene-aS-dicarboxyIic acid, a reaction which
is explicable on the assumption that benzoin is first converted into
to-dihydroxystilbene, and that this substance then condenses with the
sodiocyano-ester according to the following scheme :

CeHj-CH-OH _ CgHs-C-OH _ C,H5-C-CH(CN)-C02H
CgHs-CO "^ CgHg-C-OH ~^ CeH5-C-CH(CN)'C02H •

Benzoin. Enolic form.

The reverse transformation, that of w-dihydroxystilbene into
benzoin, occurs, according to Thiele {Anncden, 1899, 306, 142), when
benzil is reduced to benzoin, the course of the reaction being indicated
by the scheme :

CfiH^.C-.0 06H5'C-OH C.H^-CH-OH

CeHg-CIO "^ CgHj-C-OH ~^ CeHj-CO

Although oj-dihydroxystilbene itself could not be isolated, deriv-
atives of it were obtained by Thiele. Thus, when a solution of benzil
in acetic anhydride, to which a little sulphuric acid had been added, was
reduced by zinc dust, two stereoisomeric forms of w-diacetoxystilbene
were obtained, each of which yielded benzoin when hydrolysed with
alcoholic potash. Similarly, Nef (Annalen, 1899, 308, 289) showed
that the addition of acetic anhydride to the product of the action of
sodium on a dry ethereal solution of benzil resulted in the formation
of w-diacetoxystilbene, a product identical with one of the modifications
previously obtained by Thiele.

A similar transformation is to be expected with ^-benzoin, the active

STUDY OF L-BENZOIN AND ITS DERIVATIVES. 1595

benzoin passing into inactive w-dihydroxystilbene, from which inactive
benzoin would be regenerated :

C.Hj-CH-OH CgHg-C-OH _^ CeH^-CH-OH

CgH^-CO ~^ CeHj-C-OH ^~ C^H^-GO

Active. Inactive. Iu;ictive.

^Benzoin might thus be expected to undergo autoracemisation. In
ordinary circumstances, however, the velocity of transformation of
^benzoin into w-dihydroxystilbeneisso slow that the substance behaves
as a stable active compound. Thus a solution of Z-benzoin in acetone
was found to retain its activity unchanged during eight days, whilst
a crystalline specimen showed no change in activity during three
months.

The presence of a trace of alkali has been repeatedly shown to
favour the enolic form in the case of keto-enolic desmotropy. In the
case of ^benzoin, the presence of potassium hydroxide or of a trace of
sodium ethoxide so increases the velocity of the reaction ^-benzoin — <-
(o-dihydroxystilbene that, in the course of a few hours, the active
benzoin is completely converted into the inactive form. In neither of
the above cases was direct polarimetric observation possible, since the
addition of alkali causes alcoholic solutions of benzoin to acquire a
purple coloration. This disadvantage is not encountered when ^-benzoin
methyl ether is used. It could then be shown that a solution of the
latter in cold alcoholic potash (OllSiV) became completely inactive
within five minutes, whilst, under the action of sodium ethoxide, an
alcoholic solution of the same substance showed no activity after
three and a-half hours.

In a few cases, racemisation has previously been attributed to keto-
enolic change. Kipping (Proc, 1902, 18, 34; compare Salway and
Kipping, this vol., 167) ascribes the ready racemisation of c?-/3-methyl-
hydrindone by alkali to isodynamic change according to the scheme :

whilst the transformation of o?-camphoric acid into ^wocamphoric acid
when heated with water is probably also due to the same cause
(compare Lowry, Brit. Assoc. Report, 1904, 211).

Experimental.

Interaction of Methyl \-Mandelate and Alcoholic Ammonia.

The conversion of methyl ^mandelate into ^mandelamide has been
described by McKenzie and Wren (Trans., 1908, 93, 312). A more
extended study of this reaction has shown that this change is apt to

1596 WREN: RACEMISATION PHENOMENA OBSERVED IN THE

bo accorapanied by a certain amount of racemisation. In order to
obtain the maximum yield of ^-mandelamide, the experimental con-
ditions have been slightly altered. The following experiment may be
considered as typical :

A solution of methyl Z-mandelate (74 grams, [a]^ - 236° for c = 3"6335
in carbon disulphide solution*) in ethyl alcohol (74 c.c.) was cooled in
ice and treated with a brisk current of dry ammonia during thirty
minutes. Subsequently, the ice was replaced by a freezing mixture of
ice and salt, and the passage of ammonia continued for a further
period of forty-five minutes. The flask was tightly corked, when,
after a few hours, a copious precipitate of Z-mandelamide separated.
The next day the mixture was cooled in a freezing mixture and the
precipitate collected, ground with ether, and again filtered. The yield
of ^mandelamide was 44 grams. Its specific rotation was determined
in acetone solution :

Z = 2,c = 1-685, an -2-42°, [aj^ -71-8°.

The pure amide {loc. cit.), dissolved in acetone, has [ajo - 73'1°
(c= 1-6416).

The alcoholic-ammoniacal filtrate obtained above was evaporated in
a vacuum at the ordinary temperature. The semi-solid mass which
remained was triturated with ether and filtered, whereby a further
crop (4-5 grams) was isolated, which, when dissolved in acetone, had
[ajo - 62-4°, and thus contained some of the r-amide :

? = 2, c = 2-235, ai5-2-79° [ajo -62-4°.

The conversion of the ester into amide is never complete. The
unattacked ester was recovered by washing the ethei'eal solutions,
obtained during the purification of the crude amide, successively with
water, dilute sulphuric acid, and finally with water. After drying the
solution over anhydrous sodium sulphate and removal of ether, the
residue was distilled under diminished pressure. The ester so recovered
from different \ experiments possessed specific rotations varying
between - 198° and - 227° when dissolved in carbon disulphide.

Z-^Iandelamide itself does not appear to suffer racemisation when its
solution in cold alcoholic ammonia is allowed to remain at the ordinary
temperature for some time. Thus a partly racemised specimen of
the amide, which possessed [ajo -62-8° in acetone solution, was
dissolved in alcohol and the solution saturated with ammonia. The
solution was kept for six days at 10°, after which the alcohol and
ammonia were removed under diminished pressure at the ordinary

* "Walden (Zeitsch. physikal. Chem., 1895, 17, 706) gives the values [o]d -214-1''
for c = 3-33 and {a]r, -217-0' for c = l'67 for the specific rotation of methyl ^man-
delate in carbon disulphide. The examination of several specimens of the ester has
shown that this value is rather low.

STUDY OF L-BENZOIN AND ITS DERIVATIVES. 1597

temperature. The residual amide had [a]„ -62-3° in acetone
solution :

1=2, c = 3-306, ao -4-12^', [a]„ -62-3°.

Partly racemised ^-mandelamide cannot be economically purified
by recrystallisation if its specific rotation falls below about - 65°.
In one case, a sample of amide (7 grams), possessing [a],, - 60° in
acetone solution, was purified by recrystallisation from a mixture
of acetone (1 vol.) and benzene (4 vols.). The crop weighed
5*6 grams, and gave the following value for the specific rotation in
acetone :

^ = 2, c = 2-10, a„ -2-61°, [ajo -62-1°.

After two more recrystallisations from the same mixture of solvents,
this value had only increased to - 62*8° :

; = 2, c = 3-05, ao -3-83°, [a]o -62-8°.

Possibly r-mandelamide and ^-mandelamide have the tendency to
form mixed crystals.

Conversion of l-Mandelamide into \-Benzoin.

The preparation of Z-benzoiu by the action of magnesium phenyl
bromide on ^-mandelamide has been described by McKenzie and Wren
(loc. cit.). Farther experience has shown that it is not necessary
to heat the mixture of amide and Grignard reagent for more than six
hours instead of eight, as previously described. The crude reaction
product, isolated as in previous experiments, possesses, after one
recrystallisation from methyl alcohol, a specific rotation of approxi-
mately - 110° in acetone solution, and is sufticiently pure to serve as
the starting point for the preparation of derivatives of ^benzoin.
Pure ^benzoin has [a]u -118-6° in acetone. As the mean of many
experiments, 10 grams of Z-mandelamide have been found to yield
2-5 grams of Z-benzoin.

Partly racemised ^benzoin cannot be purified by recrystallisation
if its specific rotation falls below about - 100°. An impure specimen
having [ajo - 82-9°, after one recrystallisation from methyl alcohol,
had [aji, -87-8°, but after two further recrystallisations from the
same solvent, this value had only increased to - 88-8°.

In consequence of the partial racemisation which occurs when
methyl ^mandelate is converted into ^mandelamide, and of the
difliculty of purifying partly racemised specimens of Z-mandelamide
and ^-benzoin, it is necessary to take special precautions that the
methyl Z-mandelate used as a starting point for the preparation of
pure ^-benzoin is as pure as possible. In one series of experiments, a
specimen of methyl ^mandelate having [a]i, -212-6° (c = 2-2715) in
carbon disulphide solution was employed. Successive preparations of

1598 WREN: RACEMISATION PHENOMENA OBSERVED IN THE

amide possessed [ajp — 64"7'^ and - 65 'P respectively when dissolved
in acetone. These were converted into ^-benzoin, which, after two
recrystallisations from methyl alcohol, had [aju —101*8°, this value
being increased to only - 104"8° after another recrystallisation from
the same solvent.

Eacemisation of X-Benzoin.

Although ^benzoin is readily racemised by alkali, it does not appear
to undergo autoracemisation. Thus ^benzoin (0"3599 gram) was
dissolved in acetone, and the solution made up to 20 c.c. A portion
of this solution, when examined in a 2-dcm. tube, had a-Q - 4" 17°. The
remainder was kept for a week. When brought into a 2-dcm. tube,
its rotation was found to be identical with that of the first portion.
Also a crystalline specimen of ^-benzoin showed no change in activity
during three months, the values for the specific rotation at the
beginning and end of that period being respectively — 115"9° and
-116-3°.

The action of alkali on Z-benzoin was studied in the following
manner. Z-Benzoin (1 gram) was boiled for thirty minutes with
50 c.c. of alcoholic potash (1 c.c. = 0'0065 gram KOH). The purple
solution was poured into water (200 c.c). After some time, the
precipitated benzoin was collected and dried in a vacuum over sulphuric
acid. Its solution in acetone was optically inactive. The crude
product was recrystallised from methyl alcohol, after which it melted
at 132*5 — 134°. In acetone solution it was optically inactive.

To a solution of ^-benzoin (0"22 gram) in ethyl alcohol (20 c.c), two
drops of sodium ethoxide solution were added, after which it remained
at the laboratory temperature during twenty-one hours. The solution
was then poured into water, and the precipitated benzoin isolated as
above. The latter was optically inactive when dissolved in acetone.

Eacemisation of l-Benzoin Methyl Ether,

Z-Benzoin methyl ether (0'2364 gram) was dissolved in cold alcoholic
potash (0'113iV) and the solution made up to 20 c.c After an interval
of five minutes, no optical activity could be detected (^=4). Similarly
a few drops of dilute sodium ethoxide solution were added to a
solution of Z-benzoin methyl ether in absolute ethyl alcohol. Five
minutes after addition, the activity of the solution had diminished
to two-thirds of its original value ; after thirty minutes to rather less
than a-half, whilst at the end of three and a-half hours no activity
was observable.

Ethylation of l-Benzoin.

An attempt was made to prepare /-benzoin ethyl ether by Fischer's
hydrochloric acid method, since Irvine and McNicoU (Trans., 1908, 93,

STUDY OF L-BENZOIN AND ITS DERIVATIVES. 1599

1601) have shown that r-benzoin can be ethylated in this manner
without the formation of by-products, such as were encountered when
r-benzoin was methylated. It was found, however, that complete
racemisation had occurred under the following conditions.

A solution of ^-benzoin (2 grams) in dry ethyl alcohol (30 grams)
was saturated with dry hydrogen chloride, first at 30 — 40° and
subsequently at the temperature of the laboratory. After five days,
the solution, which showed only feeble reducing action towards boiling
Fehling's solution, was poured into water and the emulsion extracted
with ether. The solid, obtained from the ethereal extract, was
purified by crystallisation from boiling light petroleum, when 1*3
grams of substance were obtained, which, after a second crystallisation,
melted at 60o — 61-5°. This product when dissolved in benzene
yielded an optically inactive solution. The melting point of r-benzoin
ethyl ether is given by Irvine and McNicoll (loc. cit.) as 62 — 63°, whereas
Fischer (i5er., 1893, 26, 2415) gives 62° and Lander (Trans., 1900,
77, 733) 58—58 5°. On analysis :

0-1562 gave 0-4597 CO2 and 0-0974 H^. C = 80-3 ; H = 7-0.
C^gHjgOg requires C = 80-0 ; H = 6*7 per cent.

Racemisation was shown to be complete by evaporating to dryness
the mother liquor from the first recrystallisation and polarimetrically
examining the solution of the residue in acetone.

It thus appears that Z-benzoin and alcoholic hydrogen chloride inter-
act to form r-benzoin ethyl ether.

The silver oxide method was next employed for the ethylation of
^benzoin. To a solution of ^benzoin (4 grams = 1 mol.) and ethyl
iodide (26-5 grams = 9 mols.) in acetone (60 c.c), dry silver oxide
(13-1 grams = 3 mols.) was added. The mixture was cautiously
heated to its boiling point and maintained at this temperature during
two and a-half hours. After filtration from silver oxide and iodide
and removal of acetone, an oil remained which had the odour of ethyl
benzoate. Since it was possible that complete alkylation had not
taken place, the product was dissolved in acetone (30 c.c.) and re-
alkylated by treatment with half the above quantities of ethyl iodide
and silver oxide. After removal of silver oxide, silver iodide, and
acetone as before, an oil was obtained which could not be caused to
crystallise. As it was conceivable that the oily nature of the product
was due to the presence of ethyl benzoate, the latter was removed by
steam distillation, but the residue could be obtained in no form other
than an oil. It was accordingly distilled under diminished pressure.
Under 6 mm. pressure a viscous, yellow oil of indefinite boiling point
(up to 175°) was obtained, which slowly solidifies when placed in a
freezing mixture. The solid was recrystallised from a small quantity

1600 WREN: RACEMISATION PHENOMENA OBSERVED IN THE

of boiling light petroleum. The whole filtrate, from which the crystals
had been removed, when examined in a 1-dcm. tube had aj, + 8"08°.
The crystals, which melted indefinitely at 64 — 61°, were polari-
metrically examined in chloroform solution :

1 = 1, c = 1-913, ay -0-22°, [aJD -5-7°.

The chloroform solution was evaporated to dryness, and the residue
examined in heptane solution :

; = 2, c=l-615, au +l-2r, [a]„ +37-4°.

The amount of substance was insufiicient for further purification.
It appears, therefore, that the product obtained was partly
racemised Z-benzoin ethyl ether, the optical properties of which are
analogous to those of the methyl ether (see preceding paper). Race-
misation is presumably due to the high temperature necessary for
distillation, since it is improbable that the mechanism of methylation
and ethylation by the silver oxide method differ, and in the former
case a fully active product was readily isolated.

Racemisation of Carbanilido-l-benzoin.

It has been pointed out in the previous paper that carbanilido-^
benzoin melts at 121-5°, but solidifies again when heated slightly above
this temperature, ultimately re-melting at 163-5°. The coincidence of
this latter melting point with that of carbanilido-r-benzoin suggested
that racemisation had taken place. To test this point, carbanilido-Z-
benzoin was heated in a soft glass tube for ten minutes at 130° and
then for eight minutes at 150°. The product, which had solidified
at the sides of the tube but not throughout the mass, was cooled and
polarimetrically examined in acetone solution, when it proved to be
but slightly racemised :

1=2, c = 0-8065, ai, -3-35°, [a]o -207-7°.

Pure carbanilido-Z-benzoin has [a]^^ -214-8° for c = 0-6528 in
acetone.

The substance was therefore further heated during three and a-half
hours at 140°, after which its solution in acetone was found to be
optically inactive. It melted at about 163°.

In the above experiment, as also in the determination of the melting
point, it was observed that the portions in contact with the glass
were invariably the first to solidify, namely, to racemise. It would
thus appear that racemisation is not conditioned solely by heat, but
also by specific contact action of the glass.

STUDY OF L-liENZOIN AND ITS DEIUVATIVES. IGOl

luteraclion of \-Benzoin and Aniline.

With the object of investigating the optical behaviour and action
towards alkali of ^benzoiuanilide, ^benzoin was coudensed with
aniline.

A mixture of ^-benzoin (2 7 grams) with aniline (1"5 grams) was
heated at 100° for four and a-half hours. The product melted at
97*5 — 'jy ', and was quite inactive. This melting point was practically
unaltered by admixture with an approximately ec^ual quantity of
r-beuzoinanilide (m. p. 98 — 99^) which had been prepared from
?'-benzoin and aniline. The product of the leaction was therefore
r-benzoinanilide.

Interaction oj \-Benzoin and Benzoyl Chloride.

The preparation of benzoyl-r-benzoin by heating together r-benzoin
and benzoyl chloride has been described by Zinin (yl«Mrt^en, 1857, 104,
116). An attempt was made to benzoylate ^benzoin in the tame
manner.

^-Benzoin (1'2 grams) was gently heated with re-distilled benzoyl
chloride (2 grams). Evolution of hydrogen chloride started at 75°.
After solution of the benzoin was complete at 100°, heating was
continued in an oil-bath. Brisk evolution of hydrogen chloride
occurred at 150°. The temperature was finally gradually raised to
195°, at which point gas evolution ceased. The cooled mixture was
vigorously agitated with 75 per cent, alcohol (20 c.c), wheieupon it
solidified. After three crystallisations from 80 per cent, alcohol,
a well-crystallised product was obtained, which melted at 124 — 125°
and was optically inactive in chloroform solution. Benzoyl-r-beuzoin,
according to Zinin, melts at 125°:

01779 gave 0 5199 CO.^ and 0-0777 Rp. 0 = 797 ; H = 4-9.
C^^Hj^Og requires 0 = 79-7 ; H = 51 per cent.

The substance obtained was therefore benzoyl-r-benzoin.

Acetylation of \-Benzoin-ix-oxiine.

^-Benzoin-a-oxime (TG grams) was covered with redistilled acetic
anhydride (4 grams). With considei-able development of heat, the
oxime rapidly passed into solution, from which, on cooling, crystals
separated. These were recrystallised from light petroleum (b. p.
60 — 80°), when colourless needles were obtained which melted at
86'5 — 87°. Their specific rotation was determined in benzene
solution :

l^i, c = 0-648, al; -0-66°, [a]l; -25-6°

VOL. XCV. 5 N

1602 WREN: RACEMISATION PHENOMENA.

In the light of the following observations, it is doubtful, however,
if this product was optically pure.

In the hope of obtaining a better yield of the acetyl derivative, the
experimental couditions were slightly altered in a second attempt.
^Benzoin-a-oxime (0"8 gram) was covered with acetic anhydride
(2 grams). Solution of the oxime readily took place. After standing
for thirty minutes, the mixture was placed in a vacuum desiccator
over soda-lime in order to remove excess of acetic anhydride and
acetic acid. The solid which remained was recrystallised from light
petroleum. The colourless needles so obtained melted at 87 '5 — 88",
and were polarimetrically examined in benzene solution :
; = 4, c = 0-974, a'^ -0'85°, [a]{« -21-8°.

The observed angle did not change during twenty-one hours. After
a second recrystallisation, the specific rotation was again determined
in benzene solution ;

; = 4, c = 0-7952, a'o' -0-75°, [aj^ -23-6°.

Although the relative quantities of oxime and acetic anhydride
were the same in both experiments, it will be observed that the pro-
duct obtained in the second case was less active than in the first.
This slight difference must be attributed to prolonged contact of the
oxime, or more probably of its acetyl derivative, with acetic anhydride.
A third experiment was made, in which the amount of the latter
reagent was greatly reduced. A partly racemised product again
resulted.

^-Benzoin-a-oxime (1'3 grams) was allowed to stand with acetic
anhydride (1*1 grams) during fifteen minutes. The semi-solid reaction
product was then brought into water, and the precipitated acetyl-^-
benzoin-a-oxime collected, dried, and twice crystallised from boiling
light petroleum. The colourless needles so obtained melted in-
definitely at 89 — 96°. Their specific rotation was determined in
benzene solution :

^ = 4, c = 1-8452, aT - 1-15°, Hir -15-6°

111 this last experiment, owing to the reduction in the amount of
acetic anhydride, the temperature attained by the reaction mixture
was considerably higher than in the former cases. The extensive
racemisation may be ascribed largely to this factor.

In conclusion, the author wishes to express his gratitude to
L)r. Alex. McKenzie for the interest which he has taken in the work
recorded in this and the preceding paper.

BiKKnBCK College,
LoNuoN, E.G.

DIKETODIPHENYLPVRROLINE ANP ITS ANALOGUES. 1008

CLXXXI. — Dikctodlplienylpyn'olinc and its Analogues.

By Siegfried Kuiikmann.

It has recently been shown (this vol., 984) that, whilst tlie sodium

compounds of fatty or fatty-aromatic amides react with ethyl phenyl-

propiolate to form diacylimides, the metallic derivatives of benzamide

CO CO

or o-toluamide yield diketodiphenylpyrroline, Y >>NII, or its

homologue respectively. It was stated, also, that this reaction seems

to be typical of the behaviour of aromatic amides with ethyl phenyl-

propiolate. The correctness of this view follows from the fact that

analogues of diketodiphenylpyrroline are produced on using the sodium

compounds of in- or/j-toluamide, of cuminamide, anisamide,or piperonyl-

amide. These substances have a deep colour, which varies from dark

rod to bx'own or black. The latter colour, accompanied by a beautiful

metallic lustre, is characteristic of the diketopyrrolines which are formed

from anisamide and piperonylamide. They all readily yield phenyl-

hydrazones, which are orange, and differ only slightly in shade ; these

are sparingly soluble in cold alcohol, and this property^ together with

their melting points, may be used for isolating and identifying the

diketopyrrolines, especially those which, on account of the ease with

which they dissolve in alcohol, cannot readily be purified. The

diketopyrrolines have the common property of dissolving in dilute

alkalis to form blue solutions, which, however, rapidly turn yellow.

This behaviour indicates their resemblance to isatin, and this is

also shown in the similarity of the formation and the behaviour of

their oximes. The oximes of diketodiphenylpyrroline and isatin are

yellow ; they both dissolve readily in alkalis to yield brown solutions.

By the action of zinc dust and acetic acid, however, isatin yields

isatide, Cji-HjoO^N.^, whereas the diketopyrroline combines with two

atouis of hydrogen and forms the compound Cj^H^gO^.N. This was

CO CO

regarded {loc. cit.) as diketodiphenylpyrrolidine, ' ^ ^ ^/^NH 3

. . , , , CH(OH)-CO. ^^,, , , , ,

yet, a prion, the formula 1 ^, ' _, "^JNH cannot be excluded.

CPh CFh

According to the latter view, the reduction product would appear as

an analogue of dioxindole, and therefore ought to resemble dioxindole

and benzoin in properties. This, however, is not the case, for the

latter compounds do not yield a colour reaction with ferric chloride,

whereas the reduction product of diketodiphenylpyrroline gives a

bluish-green coloration on the addition of ferric chloride to its

5 N 2

1604 IIUHEMANN: DIKKTODIPHENYLPYRKOLINE

alcoholic solutioc. This fact proves the correctness of the view

that the compound Cj^HjyOjN is diketodiphenylpyrrolidine. This

constitution, moreover, is supported by the following consideration.

Diketodipheuylpjrrolidine may be represented by the tautomeric

, C(OH)-C(OH). ,,,.,.
formula: m' , ^Vtt^/^-N, which points to the relation of the coiu-
CPh CHFh

pound to catechol. This relation, indeed, exists, for both compounds

give similar colorations with ferric chloride, are readily soluble iu

dilute alkalis, and reduce ammoniacal silver solutions. The presence

of an ethylene linking in diketodiphenylpyrroline is proved, not only

by the ease with which the substance combines with hydrogen, but

also by its uniting with bromine to form dibromodiketodiphenyl-

pyrrolidine, (^^rPh. CBrPh>^^-

The results arrived at in the course of the study of the reaction of
ethyl phenylpropiolate with amides induced me to investigate the
behaviour of the acetylenic ester towards mono substituted carb-
amides. That the latter substances, on treatment with sodium
ethoxide, form metallic derivatives had been previously shown by
Blacher {Ber., 1895, 28, 433) in the case of phenylcarbamide ; these
metallic compounds, however, do not condense with the ester to form
cyclic substances, but acyl derivatives of carbamide are produced.
This reaction, therefore, is similar to that between fatty or fatty-
aromatic amides and ethyl phenylpropiolate (compare Ruhemann,
this vol., 987). For the compound which is formed from phenyl-
carbamide, the following formulae are possible :

CPh:C-CO-NH-CO-NHPh (I.) or CPh-C-CO-NPh-CO-NH^ (II.)

The first, however, according to which the sodium derivative of
phenylcarbamide is to be represented by CgH^'NH'CO'NH'Na (III),
appears to be more probable for the following reason. Some time ago,
Euhemann and Stapleton (Trans., 1900, 77, 239) showed that, in the
presence of sodium ethoxide, carbamide reacts with ethyl phenyl-
propiolate to yield a yellow compound, which, from the fact that on
boiling with potassium hydroxide it yields phenylpyruvic acid, has

riQ TsT IT

the constitution : CgH5'CH!C<^ ' . Phenylpropiolylphenylcarb-

amide, however, is colourless, and behaves towards alkalis quite
differently from benzylidenehydantoin. It follows, therefore, that the
sodium derivative of phenylcarbamide is to be expressed by (III), and,
accordingly, phenylpropiolylphenylcarbamide by (I) ; again, if sodio-
phenylcarbamide had the formula CyHj^'NNa'C0*NH2, and the
product of its reaction with ethyl phenylpropiolate the formula (H),

AND ITS ANALOGUES. 1605

it was to be expected that it would condense to a cyclic compound
similar to benzyl idenehydantoin.

EXPKIUMKNTAL.

Oxime of DikeiodipJienylpyrroline, • ' ^ ^NII. — This

compound is readily formed by the method which Marchlewski (Ber.,
1896, 29, 1031) used for the preparation of isatoxime. For this
purpose the pyrroline (1 gram) is dissolved in hot glacial acetic acid,
and the solution, after the addition of hydroxylamiae hydrochloride
(0"5 gram) and an excess of sodium acetate, boiled for a short time.
The deep red colour disappears, and a yellow solid separates. This
is insoluble in water, spxringly soluble in ether, more readily so in
boiling alcohol, and, on cooling the concentrated alcoholic solution,
crystallises in small, yellow needles, which melt and decompose at
200—201°:

0-1497 gave 14 c.c. N^ at 20° and 760 mm. N = 10-69.
CjgHj20^N2 requires N = 10-60 per cent.

The oxime dissolves in cold dilute potassium hydroxide, as well as in

sodium carbonate, yielding brown solutions, from which the oxime

is precipitated unchanged on the addition of hydrochloric acid.

CO CO

BibromodiphenyldiJatopyrrolidine, i pi .nu Pv,^''^^" — ^^ ^^^'

viou'ily stated, diketodiphenylpyrroline, on treatment with zinc dust
and acetic aci<l, is reduced to diketodiphenylpyrrolidine. This readily
dissolves in dilute potassium hydroxide to form a colourless solution,
from which the pyrrolidine is precipitated on the addition of mineral
acids. Diketodiphenylpyrroline also combines with bromine, and is
transformed into the dibromo-derlvative. This is prepared by adding
bromine (0 6 gram) to the pyrroline (1 gram) dissolved in glacial acetic
acid, when the deeply-coloured solution turns light red and, on pouring
it into water, yields a solid. This is sparingly soluble in light
petroleum, moderately so in hot alcohol or benzene, and, on adding
light petroleum to its solution in benzene, is obtained in light brown
needles which melt and decompose at 175° :

0-2305 gave 68 c.c. Ng at 18° and 767 mm. N = 3-44.

0-2340 „ 0-2137 AgBr. Br = 38-86.

CiflHi^O^NBro requires N = 3-42 ; Br = 39*12 per cent.

Formation of Analorjues of Diketodiphenylpyrroline.

These compounds have been prepared in the same way as diketo-
diphenylpyrroline, namely, by the action of ethyl phenylpropiolate on

1606 lUTHEMANN : DIKETODTPHENYLPYRROLINE

the sodium derivatives of aromatic amide?. The latter products

are obtained in a purer state by using metallic sodium in the form

of wire tlian by evaporating in a vacuum a mixture of alcoholic

solutions of the amides and sodium ethoxide. Absolute ether as a

solvent is generally preferable to benzene, because the disappearance

of the metal requires less time than in the presence of benzene, even

in those cases where the amides are only sparingly soluble in ether.

It is not necessary to use the large amount of the solvent which is

required for their solution, but it is sufficient to digest the amide,

suspended in ether, with the metal on the water-bath, when in the

course of one to two days the sodium completely disappears.

CO CO

2:3-Diketo-4:-pheni/l-5-m-tolylpyrroline, Xrii,'n/n xr i\t x!!^-^-^' — ^^

U jt h . U (^ Ugxi^ J\ie )

digesting ethyl phenylpropiolate (9 grams) with sodio-j)i-toluamide,
obtained by the action of sodium wire {1'2 grams) on the amide
(7 grams), suspended in absolute ether, no reaction takes place until
the ether is removed by distillation from the water-bath, when with the
rise of temperature the whole becomes blue. To complete the reaction,
the residue is boiled with dry benzene for an hour. After evaporation
of the benzene, water is added, when the blue colour disappears. The
solution which is formed is freed from unaltered amide and ethyl
phenylpropiolate by extraction with ether, and the aqueous layer
saturated with carbon dioxide, A coloured, gelatinous solid is
precipitated, which is removed by extraction with ether; finally, the
yellow, aqueous solution which remains is treated with dilute hydro-
chloric acid, when the diketopyrroline is precipitated as a red oil
which shortly sets to a solid. This dissolves readily in ether or hot
alcohol, and, on cooling the alcoholic solution, crystallises in dark
brown prisms, which melt at 150°, after having begun to soften a little
before :

0-2205 gave 10-2 c.c, Ng at 20° and 769 mm. N = 5-35,
C^7Hj302N requires N = 5'32 per cent.

On boiling the diketopyrroline, dissolved in alcohol, with an excess
of phenylhydrazine on the water-bath, the deep red solution turns
light red, and, after a short time, the phenylhydrazone of diketophenyl-
OT-tolylpyrroline separates as a crystalline solid. This is scarcely
soluble in cold, moderately so in boiling, alcohol, and crystallises
in beautiful red needles, which melt and decompose at 217 — 218° :

0-2115 gave 21-8 c.c, ^2 at 20° and 769 mm. N = 11-92.
C.^jHjrjONg requires N = 11-90 per cent.

2 : 3-Diketo-i-phenyl-5-p-toly?pyrroUne, J^ . •^NH. — This

C/i h.C{Cj.U.Mp)

compound is prepared in the same way as its isomeride, namely,

AND ITS ANALOGUES, 1607

by digesting ^-toluamide (13"5 grams), suspended in absolute
ether, with sodium wire (2"3 grams) until the metal has disappeared,
and adding othyl pliejiylpropiolato (17'*t grams). Tlie reaotion in this
case, also, does not take place until tlio ether is removed and the
mixture boiled with benzene for two to three hours on the water-bath.
The blue residue which is left on distillation of the benzene is
subjected to the same treatment as before, when a dark solid is
obtained which dissoh^es readily in hot alcohol and separates in
peddish-brown prisms ; these are soluble in ether or benzene, and
melt at 200° :

0-1788 gave 05070 CO3 and 0-0815 HgO. C = 77-33 ; H = 5-06.
0-2208 „ 10-4 c.c. N2 at 19° and 764 mm. N = 5'44.

Ci^HjgOoN requires C = 77-57; H = 4-94; N = 5-32 per cent.

The jihenylhydrazone separates as a red solid on digesting an alcoholic
solution of the diketopyrroliue with an excess of phenylhydrazine for
half an hour on the water-bath. It dissolves in much boiling alcohol,
and crystallises in rod needles, which melt and decompose at 233 — 234° :

0-2095 gave 21-8 c.c. Nj at 20° and 764 mm. N = 11-96.
CggHjgONg requires N = 11-90 per cent.

CO • C 0-v,.

2 '. '6-Diketo-i'pIienyl-5-cu7nylpyrroline, n-pu'n/n rx r< tr \-^-^^^- —

LJr'h.L^O^jH^'UgHy)

On adding ethyl phenylpropiolate (8-5 grams) to the magma of

sodiocuminamide which is formed on digesting the amide (8-2 grams),

suspended in absolute ether, with sodium wix'e (I'l grams) for two days,

no reaction takes place until, after the removal of the ether, the

residue is heated on the^water^bath alone or in the presence of benzene.

The product, when subjected to the same treatment as before, yields

the diketopyrroline, which readily dissolves in boiling alcohol and,

on cooling the solution, crystallises in dark brown prisms, The

substance is moderately soluble in ether, and melts at 185° :

0-1632 gave 0-4680 CO2 and 0-0865 H2O. C- 78-20; H = 5-89.

0-2195 „ 9-4 c.c. N2 at 22° and 765 mm. N = 4-83.

CigHjyOoN requires 0 = 78-35; H = 5-84; N = 4'81 percent.

The jjhenylhydrazone separates on boiling the alcohol solution of the
diketopyrroline with phenylhydrazine on the water-bath. It is only
sparingly soluble in cold, more readily so in boiling, alcohol, and
crystallises in bunches of red needles, which melt at 217 — 218°:

0-2187 gave 21-4 c.c. Ng at 21° and 757 mm. N = 11-10.
C25H03ON3 requires N= 11-02 per cent.

CO CO'^^

2 : 3 -Dikeio - 4 -jjhenyl - 5 - anisylpyrroline, Ar»uT</n tit n^.'v v-^^H-

-^Anisamide (7"6 grams), which, like the former amide, is prepared

1608 RUHEMANN: DIKETODIPHENYLPYRROLINE

in the usual way, namely, by the action of ammonium carbonate
on anisoyl chloride, is transformed into its sodium derivative by
suspending it in absolute ether and digesting it with sodium
wire (1'2 grams). On adding ethyl phenylpropiolate (8 7 grams),
distilling off the ether, and boiling the residue with dry benzene, the
mixture gradually turns blue, and, after two hours, the reaction is
complete. The solid which is left on removal of the benzene by
distillation from the water-bath is treated as in the former cases, and
yields a dark precipitate. This is only sparingly soluble in ether or
cold alcohol, moderately so in boiling alcohol, and, on cooling the deep
red alcoholic solution, separates in prisms which, when small, are dark
brown, but black when large, and then possess a metallic lustre. They
melt and decompose at 254 — 255° :

0-2020 gave 0-5413 COg and 0-0885 H.fi. C = 73-08 ; H = 4'86.

0-2200 „ 9-6 c.c. N2 at 17° and 764 mm. N = 5-09.

CyHigOgN requires 0-73-12; H-4-66; N = 5-02 per cent.

The phenyl hydrazone crystallises from alcohol in curved, red needles,
which melt and decompose at 230° It is formed in the same way as
in the former cases, with the only exception that the diketopyrroline
and phenylhydrazine must be used in molecular quantities, otherwise
decomposition takes place.

QQ CO-N.

2:3- Diketo - 4 - phenyl - 5 - -piper onylpyrroline, Xi^, .^ ,^ ^^^ „ x>NH.

CJrh.C^OyUgOo)

— Piperonylamide, which is required for the formation of this com-
pound, was prepared according to the directions of Rupe and von
Majewski {Ber., 1900, 33, 3403) by the action of hydrogen peroxide
on piperonylonitrile in weakly alkaline solution. Its sodium derivative
was prepared by the action of sodium wire (1-4 grams) on the amide
(10-2 grams), suspended in dry benzene, two days' beating on the
water-bath being necessary for the metal to disappear. On adding
ethyl phenylpropiolate (10-5 grams), hardly any change was noticeable
even after two hours' boiling ; a reaction, indicated by a blue colora-
tion of the mixture, does not take place until, after the removal of the
benzene by distillation from the water-bath, the temperature rises.
The heating was continued for an hour, and the residue treated as
before, when the diketopyrroline was obtained as a dark solid. This is
only sparingly soluble] in ether or cold alcohol, moderately so in
boiling alcohol, and, on cooling the deep red alcoholic solution, gradu-
ally separates in black plates which possess a metallic lustre. The
substance melts at 237 — 238°, after having begun to soften a few
degrees before :

0-2000 gave 0-5102 CO, and 0-0710 HgO. C- 69-57; H = 3-94.

0-2280 „ 9-8 c.c. Na'at 21° and 754 mm. N = 4-85.

Oj^Hj^O^N requires 0 = 69-62; H = 3-75; N = 478 per cent.

AND ITS ANALOGUES. 1609

As in the previous case, for the preparations of the phenylhydrazone
molecular quantities of the dikctopyrroline and phenylhydrazine are
used. After about an hour's heating of the alcoholic solution of the
mixture, a rod solid separates ; this dissolves in much boiling alcoliol,
and, on cooling tlie solution, crystallises in deep rod needles which
melt and decompose at 250 — 251° :

0-2210 gave 21-4 c.c. Ng at 21° and 755 mm. N = 10-94.
CgjHj-OaNg requires N = 1097 per cent.

Action of Ethyl riienylpropiolate on Monoarylcarhamides.

This reaction differs from that between carbamide and the acetylenic
ester (see Ruhemanu and Stapleton, lac. cif.) inasmuch as it does not
yield cyclic compounds, but acyl derivatives of carbamide, which, as
stated before (p. 1604), are to be represented thus :

Cyi^-C-C-CO-NH-CO-NHR (R denoting an aryl group).

Phenyl fropiolylpUnylcarhamide, C^H^-CiC-OO-NH-CO-NH-CyHs.—
This compound is readily prepared by mixing solutions of sodium
(1'2 gi'ams) and phenylcarbamide (6 8 grams) in absolute alcohol and
distilling the solvent in a vacuum from the water-bath. To the sodium
derivative of the carbamide which is formed, dry benzene and ethyl
phenylpropiolate (9 grams) are added, and the mixture then boiled ;
after a short time, the whole sets to a semi-solid, white mass. The
heating is continued for one to two hours, the benzene evaporated, and
the residue agitated with ether, which removes unaltered phenylcarb-
amide and the acetylenic ester. The portion which is insoluble in ether
contains the sodium derivative of phenylpropiolylphenylcarbamide ; it
dissolves, although not readily, in cold water, and the aqueous solution
yields a white solid on the addition of dilute hydrochloric acid. This is
sparingly soluble in ether or cold alcohol, but readily so in boiling
alcohol, and crystallises in colourless, stout prisms, which melt at 205°:

0-1960 gave 0-5220 CO., and 00820 \\p ; C-72 6.3 ; H = 4-64.

0-2172 „ 20 c.c. N2 at 17° and 760 mm. N = 10-63.

CigHi202N2 requires 0 = 72-72 ; H = 4-54; N = 1061 per cent.
P/ien2/^;jro;;tVy^p-«o?ycarZ.a»a'./e,O^H5-C:C-CO-NH-CO-NH-C,,H^-CH3,
is prepared in the same way as the former compound on using ;>tolyl-
carbamide ; it is sparingly soluble in ether, readily so in boiling alcohol,
and separates in colourless pi'isms, which melt at 192°:

02272 gave 20 c.c. N2 at 17° and 753 mm. N = 10-12.
Oj^H^^O.^Ng requires N= 1007 per cent.

The further study of the diketopyrrolines is in progress, and will be
recorded shortly.

University Chemical Laboratoht,
Cambuiuge.

1610 PYMAN : ISOQUINOLINE DERIVATIVES. PART II.

("LXXXll. — isoQuinoUne Derivatives. Fart IT. The

Constitution of the Reduction Products of Papaverine.

By Frank Lee Pyman.

In a previous paper (this vol., p. 1266) it was shown that
laudanosine can be readily oxidised to 4 : 5-dimethoxy-2-/3-methyl-
aminoethylbenzaldehyde by means of sulphuric acid and manganese
dioxide, and it consequently became of interest to investigate the
action of this reagent on other similarly constituted compounds,
amongst others on the hitherto unknown iV-benzoyltetrahydro-
papaverinc. For this purpose, a quantity of tetrahydropapaverine
was required, and the preparation of this compound was accordingly
commenced by Goldschmiedt's method. This chemist (Monatsh.,
1886, 7, 485; 1898, 19, 324) obtained by the reduction of
papaverine a crystalline ba.se melting at 200 — 201° which he
termed " tetrahydropapaverine," together with an amorphous base
from which no crystalline derivative was obtained. Some years
later, Freund and Beck {Be?:, 1904, 37, 3321) obtained by the
electrolytic reduction of papaveraldine an amorphous base, from
which they prepared, through the nitrosoamine, a crystalline
hydriodide; analyses of this salt were in agreement with the
formula C2()H2.-04N,HI, and they named the base provisionally
" fsv^tetrahydropapaverine," while pointing out that no such
isomeride of Goldschmiedt's tetrahydropapaverine would be expected
from consideration of Goldschmiedt's papaverine formula, and
suggesting as an alternative that the base might have been formed
by reduction and condensation of two molecules of papaveraldine
to form a pinacone, and subsequent further reduction to a com-
pound, (C2oHo404N)o.

It is shown in the present communication that the amorphous
base resulting from the reduction of papaverine (I) is tetrahydro-
papaverine (II), and is identical with Freund and Beck's
" isotetrahydropapaverine," and that Goldschmiedt's so-called
" tetrahydropapaverine " is, in reality, a dihydropapaverine,
namely, 6 : 7-dimethoxy-l-veratryl-l : 2-dihydro?.sY>quinoline, which it
is proposed to designate 1 : 2-dihydropapaverine (III), in order to
differentiate it from the 3 : 4-dihydropapaverine (IV) of Pictet and
Finkelstein (Ber., 1909, 42, 1987).

The amorphous base obtained by the reduction of papaverine,
either by Goldschmiedt's method, or more conveniently by the
method given lat^r, can be roughly separated from the crystalline
base accompanying it by means of its easy solubility in ether, and

I

PYMAN: ISOQUINOLINE DERIVATIVES. PART 11. 1611

then purified through the hydriodide. It readily jrields crystalline
salts, of which the hydrochlniiilt., hydriodide, miiichloridc, and
CH CH,

MeOf Y \^CH Me'

MeO' Ky^N MeO

C

OINIe

MeO
MeOk A />3R MeO

/\

I 'oMe

OMe • OMe

(HI.) (IV.)

2)ic?rife have been prepared, and the analyses of these lead to the
empirical formula of tetrahydropapaverine, C20H25O4N, for this
base; the amorphous nature of this base, the properties of its
hydriodide, m. p. 259 — 260'^ (corr.), and those of its nitrosamine,
m. p. 135 — 136° (corr.), shov/ that it is identical with Frcuud and
Beck's " /.sotetrahydropapaverine," of which the hydriodide is stated
to melt at 255° and the nitrosamine at 138°.

The amorphous base readily yields a crystalline 'i^-henzoyl
derivative, C.27H09O5N, of which the molecular weight has been
determined, and shown to be that required by the simple formula,
and the action of bromine on this benzoyl derivative in chloroform
solution results in the formation of a crystalline &;-o??w-derivative,
CovHosO.-.NBr.

The oxidation of the T-benzoyl derivative (V) leads to an
important result, for there are formed benzoic acid, veratraldehyde,
and a new base, 6: l-dinntliory-^: 4:-d}hi/Jroisorjuinolifie (VI), the
methochloride of which is identical with 6 : 7-dimethoxy-2-methyl-
3 : 4-dihydro/.soquinolinium chloride (VII). Since the latter com-
pound has been obtained by the action of hydrochloric acid on
4 : 5-dimethoxy-2-)3-methylaminoethylbenzaldehyde (VIII), which
has been prepared by the oxidation of laudanosine (IX) (i\"-methyl-
tetrahydropapaverine), it follows that the amorphous base is

1612 PYMAN : ISOQUINOLTNE DERIVATIVES. PART II.

tetrahydropapaverine. This argument is illustrated by the follow-
incj scheme :

CH

l\reO/ Y ^Cn, MeO-

+ (Jc,Hj(,()3

CH

(VI.)
I+CH3CI

CH

MeO
MeO

^le<\ A /XAT« MeOl A NHMe

CHO

(VIII.)

\ .OMe

OMe

(IX.)

The foregoing conclusion is further borne out by the fact that
the amorphous base actually yields laudanosine on methylation.
Freund and Beck (Joe. cit.) state that the amorphous base yields,
with methyl iodide in ethereal solution, crystals which are probably
the hydriodide of the methylated base. The reaction is, however,
less simple ; on adding methyl iodide to an ethereal solution of
tetrahydropapaverine, an amorphous deposit was obtained, which
was separated by fractional crystallisation from alcohol into
tetrahydropapaverine hydriodide, laudanosine hydriodide, and
laudanosine methiodide, which appear to be formed in approxi-
mately equal parts according to the equation :
3R:NH + 3MeI = R:NH,Hr + R:NMe,HI + R:NMe,MeT(R = C2oH2404).

It is, therefore, proved beyond question that the amorphous base
is tetrahydropapaverine.

Since Goldschmiedt's papaverine formula only allows of the
formation of one optically inactive tetrahydropapaverine, it is clear
that this chemist's so-called " tetrahydropapaverine " must possess
another constitution. Now, an examination of Goldschmiedt's

PYMAN: ISOQUINOLINE DERIVATIVES. PART II. 1613

analytical numbers shows that, whereas some of the results obtained
by the analysis of the base and its derivatives are in good agree-
ment with those calculated for the formula CooHojO^N, others
approximate more closely to those required by the formula
CoyHosO^N. For example, the analyses of the hydrochloride and
nitrosamine, as well as that of the base given in his second paper,
show in round figures 0"3 per cent, of hydrogen less than that
calculated for the formula CooHojO^N. On the other hand, the
analytical results obtained by Pope and Peachey (Trans., 1898, 73,
893) for the racemic and optically active forms of this base are
in excellent agreement with this formula. It was therefore neces-
sary to reinvestigate this base. The base,, its hydrochloride, and
'i^-be7izoyl derivative were accordingly carefully purified and
analysed, when the results obtained decided definitely in favour of
the formula CoQn2304N. Further, the corresponding papaveroline
derivative was also prepared by the removal of the four methyl
groups, and its hydrochloride gave, on analysis, figures agreeing
with those required by the formula CiqIIi504N,HC1, corresponding
with the formula of the methylated compound CoqHosO^N ; tttra-
hydropapaveroline hydrochloride, on the other hand, which was
prepared from tetrahydropapaverine for the purpose of comparison,
gave, on analysis, figures agreeing with the expected formula
CigHj-O^NjHCl, corresponding with the formula of the methylated
compound CoqHo^O^N; this result is important, since the difference
in hydrogen content between the formulas of the two hydrochlorides
amounts to 0"6 jDer cent. A determination of the molecular weight
of the base proved it to have the simple formula. The only possible
conclusion from these facts is that this crystalline base obtained
by the reduction of papaverine is a dihydropapaverine, and, since
Pope and Peachey {loc. cit.) have resolved it into its optically
active forms, and thereby shown that it contains a hydrogen atom
in the 1-position, and Goldschmiedt has prepared a nitrosoamine
from it, thus proving it to contain an imino-group, this base must
consequently be 1 : 2-dihydro23apaverine.

1 : 2-Dihydropapaverine is a comiDOund of considerable stability,
and has thus far resisted attempts to effect its reduction. In this
respect it differs from a compound of similar type, 1-benzyl-
2-methyl-l : 2-dihydro/soquinoline, recently described by Freund
and Bode {Ber., 1909, 42, 1762), which readily yields 1-benzyl-
2-methyltetrahydroisoquinoline when reduced with tin and hydro-
chloric acid, although the reduction is incomplete when sodium and
alcohol are employed. This difference in behaviour between
1 : 2-dihydropapaverine and l-benzyl-2-methyl-l : 2-dihydro2so-
quinoline must probably be ascribed to the presence of the free

1614 PYMAN : iSOQtJlNoLlNfi DEHIVATIVES. PART II.

imino-group in the former, and this view is supported by the fact
that the unknown iY-methyl ether of 1 : 2-dihydropapaverine has
not been obtained in the reduction of j^apaverinc methochloride,
irt \vhich hitherto only laudanosine has been isolated (Pictet and
Athuuascscu, Bcr., 1900, 33, 2346).

iV-Benzoyl-l : 2-dihydropapaverine is also a very stable compound ;
it is not readily attacked either by bromine or by suljihuric acid
and manganese dioxide, thus differing markedly from i\'-bcnzoyl-
tetrahydropapaverine.

Experimental.

Bednciion of Faimverine.

One hundred grams of papaverine were dissolved in a mixture
of 400 c.c. of alcohol and 400 c.c. of concentrated hydrochloric
acid, and boiled with 200 grams of granulated tin under a reflux
condenser for five hours. Further quantities of 50 grams of tin
and 200 c.c. of hydrochloric acid were then added, and the mixture
boiled for another seven hours. The alcohol was then removed by
distillation, and the acid liquor cooled and diluted with water,
which caused the precipitation of double salts of tin and the
alkaloids in a white, amorphous condition. These were collected,
washed with water, dissolved in 3 litres of boiling water, and
decomposed with hydrogen sulphide. The resulting solution of the
hydrochlorides was filtered from tin sulphide, rendered strongly
alkaline with sodium cai'bonate, and completely extracted, first
with ether, and then with chloroform.

The ethereal residue amounted to 65 grams of sticky oil; this
dissolved to a clear solution in dilute hydrochloric acid, and the
solution gave, on the addition of solid potassium iodide, an
amorphous precipitate, which became crystalline after boiling with
absolute alcohol, and furnished 55 grams of pvire tetrahydro-
papaverine hydriodide, melting at 259 — 260° (corr.).

The chloroform residue amounted to about 15 grams of a brown,
viscid oil, and gave 14 grams of a crystalline hydrochloride when
mixed with dilute hydrochloric acid. On dissolving this in water,
adding aqueous sodium carbonate, and i-ecrystallising the separated
base from absolute alcohol, more than 8 grams of 1 : 2-dihydro-
papaverine, melting at 201 — 202° (corr.), were obtained.

The mother liquors obtained in the purification of the two bases
contained further quantities of these compounds.

Telru]i.ydr(jj)a2)averine (II, p. 1611).

This base has only been obtained in an amorphous form; it
remains as a colourless, viscid gum on the evaporation of its

PYMAN : ISOQUINOLINE DERIVATIVES. PAllT 11. 1615

solutions in various solvents. It is moderately readily soluble in
water, insoluble in light petroleum, and readily soluble in the
other usual organic solvents. On dissolving this base in hydro-
chloric acid and adding an excess of sodium nitrite solution,
tetrahydropapaverinenitrosoamine separates as a sticky oil, which
becomes crystalline on stirring with alcohol, and separates from
alcohol in short needles which melt at 135 — 136° (corr.).

Tctrahydropapavci'ine forms beautifully crystalline salts.

The hydriodide, of which the preparation has already been
described, crystallises from water in prisms Avhich melt at 259 — 260°
(corr.) after becoming yellow a few degrees below this point. This
salt is anhydrous, and is very sparingly soluble in water or alcohol :

0-1512 gave 0-2832 OOo and 0-0748 HoO. C = 51-l ; H = 5-5.

0-1885 „ 0-0942 Agl. 1 = 27-0.'
aoHo504N,HI requires C = 51-0; H = 5-6j 1 = 27-0 per cent.

The hydrorldoride was' obtained by double decomjoosition of the
hydriodide with silver chloride; it crystallises from water in glisten^
ing prisms, which sinter at 81° and melt at 83 — 85° (corr.) to an
opaque liquid, and contains 4^ molecules of water of crystallisation,
of which 3^ are lost at 100°. After recrystallisation from absolute
alcohol, this salt is obtained as an anhydrous, crystalline powder,
which melts at 217 — 219° (corr.). It is sparingly soluble in water,
and very sparingly so in alcohol :

0-6950 hydrated salt, air-dried, lost 0-0967 at 100°. H2O = 13-9.
0-1610 „ „ dried at 100°, gave 0-3590 COg and 00977 IIoO.

C=^60-8; H = 6-8.
C^B.<^^Oi^,TLC\,UH^O, losing S^HoO, requires loss = 13-7 per cent.

C2oH2504N,HCl,H20 requires 0 = 603; H = 7-l.
0-1527 anhydrous salt gave 0-3540 CO., and 00953 HoO. C = 63-2;

H = 7-0.
0-1900 anhydrous salt gave 0-0699 AgCl. Cl = 9-1.
CooHgsO^N.HCl requires 0-632; H = 6-9; 01 = 93 per cent.

The aurichloride crystallises from absolute alcohol in radial
clusters of deep yellow needles, which blacken and decompose at
176° (corr.). This salt is anhydrous, and is very sparingly soluble
in water and sparingly so in alcohol :

0-2546 gave 0-0739 Au. Au = 29-0.

OgoHg.oO^NjHAuOlj requires Au = 28-9 per cent.

The jncratt crystallises from absolute alcohol in clear, yellow,
irregular prisms, which begin to sinter at 155° and decompose at
161 — 162° (corr.). This salt gradually becomes orange super-
ficially; it is anhydrous, and is very sparingly soluble in wat^r or
alcohol :

1616 I'YMAN: ISOQUINOLINE DEUIVATIVES. PART II.

01295 gave 02578 CO., and 0-0536 HoO. C = 54-3; H=4-6.
Co(,H250^N,C6H30-N3 requires 0 = 545; H = 4-9 per cent.

Methylation of Tetrahydropa-paverine.

Seventeen grams of pure tctrabydropapaverine hydriodide were
moclianically shaken with 100 c.c. of chloroform and 100 c.c. of
10 per cent, aqueous sodium carbonate for fifteen minutes, and
the chloroform solution evaporated to low bulk. The residue was
mixed with 50 c.c. of moist ether, and 15 grams of methyl iodide
wei'e then added. The solution became tvirbid almost imme-
diately, and deposited a light brown, amorphous solid. After
twelve hours, the supernatant liquor was poured off, and gave, on
evaporation, 0"4 gram of light brown oil, which was added to the
solid residue. The amorphous deposit was fractionally extracted
with boiling absolute alcohol, and the various crops of crystals
obtained from the extracts were separated by fractional crystal-
lisation, and gave the following products :

(1) 4'8 Grams of tetrahydropapaverine hydriodide. This salt
melted at 259 — 260° (corr.), and its melting point suffered no
depression when the salt was mixed with the pure substance :

0-1520 gave 0-2860 CO. and 0-0771 HoO. 0 = 513; H = 5-7.
0-1978 „ 0-0984 Agl. 1 = 26-9.
02oHoAN,HI requires 0 = 51-0; H = 5-6; 1 = 27-0 per cent.

(2) 4-8 Grams of laudanosine methiodide. This salt melted at
213 — 215° (corr.), and its melting point suft'ered no depression
when the salt was mixed with the pure substance :

01519 gave 02945 OO2 and 00825 HgO. 0 = 52-9 ; H = 6-1.
0-1519 „ 0-0726 Agl. 1 = 25-8.
02iH2704N,CH3l requires 0 = 52-9; H = 6-0; 1^255 per cent.

(3) 11 Grams of laudanosine hydriodide. This salt melted at
201 — 203° (corr.), and its melting point suffered no depression
when the salt was mixed with the pure substance prepared by
neutralising laudanosine with hydriodic acid. This salt is
anhydrous, and is sparingly soluble in water or cold absolute
alcohol :

01534 gave 0-2900 CO2 and 0-0814 H2O. 0 = 51-6; H = 5-9.

0-2010 „ 0-0965 Agi. 1 = 25-9.
C2in2704N,HI requires 0 = 51-9; H = 5-8; I = 26'2 per cent.

Besides the above quantities of pure salts, a number of fractions
consisting of mixtures were obtained. These were combined, dis-
solved in water, and mixed with aqueous sodium carbonate; this
caused the precipitation of 2-0 grams of a brown oil, which solidified
on cooling, and proved to contain a large proportion of laudanosine.

PYMAN : ISOQUINOLINE DERIVATIVES. PART II. 1017

'M-Bcn zoi/lte trail i/dropapave line (V, p. 1612),

This compound was prepared by benzoylating tctrabydro-
papavcrine in a manner similar to that applied to 1 : 2-dihydro-
papaverine.

^-lic nzoylt et ra]iijdroi)a'paverine crystallises from absolute alcohol
in clusters of glistening, prismatic needles, which melt at 159 — 160°
(corr.). It is very sparingly soluble in water or ether, sparingly
so in acetone or alcohol, but readily so in chloroform. It is
insoluble in dilute acids or alkalis :

0-1527 gave 04050 CO.^ and 00911 ILO. C = 72-3; H = 6-7.

0-1538 „ 4-2 c.c. No at 22° and 754 mm. N = 3-l.

C.,7Ho905N requires C = 72-4; H = 6-5; N = 3-l per cent.

Molecular weight determination by the ebullioscopic method :

0-2270 in 12-37 benzene gave M O'llO. M.W. = 445.

0-4070 „ 12-37 „ „ ^t 0-195. M.W.=451.
C27H29O5N requires M.W. = 447.

liro/no-'N-henzoi/ltetrahi/dro2yapaveriiie, CgyHggOjNBr.

Two grams of iV-benzoyltetrahydropapaverine were dissolved in
20 c.c. of chloroform, and a solution of 1 gram of bromine in
30 c.c. of chloroform was added. The mixtvire was kept for forty
hours, and then allowed to evaporate spontaneously; the gummy
residue was dissolved in a little alcohol, and mixed with aqueous
ammonia, when 2-2 grams of bromo-A'-benzoyltetrahydropapaverine
separated as an oil, which became crystalline on keeping; this
yield represents 93 per cent, of the theoretical.

Bromo-^-heiizoyltetrahydrojJapaverine crystallises from absolute
alcohol in clusters of colovirless, square leaflets, which melt at
185 — 186° (corr.); it is insoluble in water, dilute acids, or alkalis,
and sparingly soluble in cold alcohol :

0-1456 gave 0-3303 COo and 00721 H.O. C = 61-9; H=5-5.

0-1961 „ 0-0706 AgBr. Br = 15-3."
CgyHgsOaNBr requires C = 61-6; H = 5-4 ; Br = 15-2 per cent.

Oxidation of 'ii^-Benzoyltetrahydropapaverine : Fon/iation of
6: 7-JJii/iethoxy-3: A-dihydroisoquinoline (VI, p. 1612).

Thirty-five grams of .V-benzoyltetrahydropapaverine, melting at
159 — 160° (corr.), were ground to a fine powder with 200 c.c. of
water, mixed with a solution of 70 grams of sulphuric acid in
1 litre of water and 17-5 grams of pyrolusite, containing 80 per
cent, of manganese dioxide, and well stirred. The temperature

VOL. xcv. 5 o

1(318 PVMAN : ISOQUINOLINE DERIVATIVES. PART 11.

was gradually raised to the full lieat afforded by the steam-bath,
and after one hour the suspension had given place to a nearly
clear, pale yellow liquor containing a quantity of resinous matter.
The latter was removed by filtration; it weighed 18 grams, of
which 3 grams consisted of inorganic material, and gave 9 grams of
unchanged .Y-benzoyltetrahydropapaverine after crystallisation from
alcohol ; the sticky mother liquors from this were neglected.

The filtrate from the resinous matter w-as completely extracted
with ether, and this in turn with aqueous sodium carbonate; the
ether left on evaporation 5"5 grams of crude veratr aldehyde, and
the alkaline extract gave on acidification 4'5 grams of benzoic
acid.

The aqueous solution of the basic products was then rendered
alkaline with sodium carbonate, and completely extracted with
chloroform ; on then adding sodium hydroxide and again extracting
with chloroform, no further quantity of material was obtained.

The chloroform extract from the sodium carbonate solution gave
on distillation a quantity of brown oil, which was purified by
distillation under 24 mm. pressure, when more than 5 grams of
6 : 7-dimethoxy-3 : 4-dihydrofsoquinoline distilled at 205 — 208°
(corr.), and formed a viscid, yellow oil with a faint blue fluorescence,
which did not crystallise on keeping :

0-1948 gave 0-4905 COo and 0-1250 H.O. C = 68-7; H = 7-2.
CiiHjgOgN requires 0 = 691; H = 6-9 per cent.

6 : 1-Dimethoxy-^ : A-dih7/droisoquinoline is readily soluble in
water and the usual organic solvents, with the exception of light
petroleum. It forms crystalline salts with acids, and combines
with methyl halides in ethereal solution, forming methyl salts which
are identical with the salts obtained by the action of the correspond-
ing acids on 4 : 5-dimethoxy-2-i8-methylaminoethylbenzaldehyde.

The base is precipitated as an oil on the addition of aqueous
sodium carbonate to concentrated solutions of its salts. The
addition of aqueous potassium cyanide to the hydrochloride in
concentrated aqueous solution causes the separation of an oil, which
is no doubt l-cyano-6 : 7-dimethoxytetrahydro?"soquinoline.

The hydi-o chloride crystallises from aqueous acetone in pale
yellow, glistening needles, which melt at 72 — 75° (corr.), and
contain 3 molecules of water of crystallisation. After drying at
100°, this salt melts and decomposes at 208° (corr.). It is very
readily soluble in water or alcohol, giving neutral solutions, which,
when dilute, show a blue fluorescence, but insoluble in acetone :

0-1548, air-dried salt, gave 0-2685 CO^ and 0-0983 HgO. C = 47-3;
H = 71.

0-2051, air-dried salt, gave 0-1070 AgCl. Cl = 12-9.

PYMAN : ISOQUINOLINE DEIUVATIVES. PART II. 1619

0-2020, air-dried salt, lost 0-0380 at 100°. HoO = 18-8.
Ciini30.N,nCl,3HoO requires C-4G-9; H = 7-2; CI -12-6;
HoO = 19-2 per cent.
0-1500, dried at 100°, gave 0-3197 CO. and 00868 IL,0. C = 58-l ;
H = 6-5.
C,,Hi30oN,nCl requires C = 58-0j 11 = 62 per cent.

The picrate cryst^alliscs from absolute alcohol in fine, golden,
silky needles, which melt at 206 — 208° (corr.), after sintering
several degrees earlier.

The mcthochloride was obtained as follows. An ethereal solution
of 6 : 7-dimethoxy-3 : 4-dihydro/soquinoline was mixed with methyl
iodide, when a deep yellow oil, which quickly became crystalline,
separated. This was dissolved in water and shaken with silver
chloride; the resulting liquor was filtered, evaporated to low bulk,
and mixed with acetone, when the methochloride separated as a
yellow, crystalline powder, which melted at 61 — 62° (corr.), and
proved to be identical with 6 : 7-dimethoxy-2-methyl-3 : 4-dihydro-
isoquinolinium chloride.*

The wethohroinide was prepared directly by the action of methyl
bromide on the base in ethereal solution ; after recrystallisation
from moist acetone it formed primrose needles, which sintered at
87 — 90° (corr.), both alone and when mixed with 6 : 7-dimethoxy-
2-methyl-3 : 4-dihydro?soquinolinium bromide prej^arcd from
4 : 5-dimethoxy-2-)8-methylaminocthyibenzaldehyde.

T etrahijdro'pa'pav eroline, CieHjyO^N.

Five grams of tetrahydropapaverine hydrochloride, containing
4iH>,0, were heated with 50 c.c. of concentrated hydrochloric acid
for three hours at 170 — 175°. On opening the tube, methyl
chloride escaped, and a clear liquid containing brown, serrated
needles remained ; the latter were collected and weighed 3-5 grams,
that is, 97 per cent, of the theoretical.

Tetrahydropa'paveroline liydrocldoride crystallises from water in
colourless, microscopic, glistening prisms, which melt and decompose
at 291 — 293° (corr.), after gradually sintering and turning yellow
from about 280°. It is very sparingly soluble in water or alcohol,
and is anhydrous :

0-1509 gave 03266 CO. and 00764 HoO. C-590; n = 5-7.

0-1764 „ 0-0793 AgCl. Cl = ll-1. "
Ci6Hi-04N,HCl requires 0 = 593; 11 = 5-6; Cl=110 per cent.

* The stateuu'ut (this vol., p. 1271) that this salt crystallises "from aqueous
solution iu a mass of primrose needles .... " should read " from aqueous acetone
in a mass of primrose needles . . . ."

5 o 2

1620 PYMAN: ISOQUINOLINE DERIVATIVES. PART II.

This salt readily reduces cold ammoniacal silver nitrate solution,
and liberates cuprous oxide from Feliling's solution on boiling. It
gives with ferric chloride, in the first instance, a deep green colour,
which quickly passes through a neutral tint to amethyst ; on the
addition of aqueous sodium carbonate, black flakes are deposited,
and the supernatant liquor becomes colourless.

Concentrated solutions of this salt give with alkalis a white
turbidity, due to the corresponding base; this is soluble in excess,
giving a pale amethyst coloration ; alkaline solutions, however, very
quickly blacken when left in contact with air.

1 : 2-DiJnj(]ropapaveri7ie (III, p. 1611).

This base has previously been described by Goldschmiedt under
the name tetrahydropapaverine, and is stated to be precipitated
from the solution of its hydrochloride on the addition of ammonia
in anhydrous needles, and to melt at 200 — 201°, after sintering at
198°. It has now been found, however, that the colourless needles
obtained by the addition of ammonia to an aqueous solution of the
hydrochloride, whether this is prepared by the above method or by
Goldschmiedt's, represent a hydrated form of the base, containing
SHgO, which, after air-drying, sinters at 65°, and finally melts at
201—202° (corr.) :

0-2062, air-dried precipitated base, lost 0-0295 at 110°. 1100 = 14-3.
C2oH2304N,3H90 requires HoO = 13-7 per cent.

01 673, dried''at 110°, gave 0-4305 COo and 0-1038 HoO. C = 70-2;
H = 70.

C20H23O4N requires C = 70-3; H = 6'8 per cent.
(C20H2.AN „ C = 70-0; H = 7-3 „ „ )

After crystallising this base from alcohol, it becomes anhydrous,
and melts at 201 — 202° (corr.) ; this melting point is unchanged by
crystallising the base from xylene, from which it separates in large
prisms. For analysis, the base was recrystallised, first from alcohol,
and then from xylene, and dried at 110°:

0-1549 gave 0-4016 COo and 0-0972 H.O. C = 70-7 ; H = 7-0.

0-1516 „ 0-3918 CO." „ 00915 H.O. C = 70-5; H = 6-8.

Molecular weight determination by the ebullioscopic method :

0-1439 in 12-05 benzene gave A^ 0-090. M.W. = 354.

0-3556 „ 12-05 „ „ A^ 0-230. M.W. = 343.

C20H2AN requires M.W. = 341.

The hydrochloride is stat<Dd by Goldschmiedt to decompose at
290°, and contain 3 molecules of water of crystallisation, of which
\h are gradually lost in dry air. After preparing this salt from
the carefully purified base, it was found, however, to decompose

PYMAN: ISOQUINOLTNE DERIVATIVES. PART II. 1621

at about 325° (corr.). It forms beautifully crystalline rods from
water, wliicli contain 5 molecules of water of crystallisation ; this
salt lias also been obtained with SPLO :

0-4012 air-dried lost 0-0789 at 110°. HoO = 19-7.

CooHoaO^NJiCl.SHoO requires HoO = 19-3 per cent.
0-2134 air-dried lost 0-0592 at 100°. rToO = 27-7.

CooHo304N,HCl,8IIoO requires HoO"=27-6 per cent.
0-1544,"dried at 110°, gave 0-3567 COo and 0-0895 HoO. C = 63-0;

H = 6-5.
0-1511, dried at 110°, gave 0-3505 CO., and 00874 HgO. C = 63-3;

H = 6-5.
0-1527, dried at 110°, gave 0-0562 AgCl. Cl = 9-1.
C.2oH230^N,HCl requires C = 63-5; H = 6-4; CI = 9-4 per cent.
(C2oH2AN,HCl „ C = 63-2; H = 6-9; CI = 93 per cent.)

The picrate was prepared from the pure hydrochloride in the
usual manner, and formed long, yellow needles, which began to
darken at 270°, and decomposed at 285° (corr.). Goldschmiedt
states that this salt turns black at 245°, and decomposes at 270°.

Attempts to effect the reduction of 1 : 2-dihydropapaverine by
means of (1) tin and fuming hydrochloric acid in alcoholic solution,
and (2) sodium and alcohol, proved unsuccessful ; in each case the
base was recovered unchanged.

N-Benzoi/l-l : 2-dihi/dropapaverine, C27H27O5N.

Five and a-half grams of 1 : 2-dihydropapaverine were
benzoylated in chloroform solution by the Schottcn-Baumann
method ; the resulting chloroform solution of the benzoyl derivative
was mechanically shaken with a large excess of 10 per cent, aqueous
sodium hydroxide, separated, dried, and evaporated. The brown
oil obtained w-as then moistened with alcohol and again evaporated
in an open dish, this process being repeated a second time, and
then dissolved in about twice its volume of absolute alcohol. On
cooling, 4-9 grams of pure .V-benzoyl-1 : 2-dihydropapaverine
separated as a crystalline powder, the yield amounting to 68 per
cent, of the theoretical.

'N-Benzoyl-1 : 2-dihydropapaverine crystallises from absolute
alcohol in colourless, transparent, glistening prisms, which melt at
234 — 235° (corr.). It is very sparingly soluble in water or ether,
sparingly so in alcohol or acetone, and readily so in chloroform :

0-1542 gave 0-4101 CO., and 0-0856 HoO. C = 72-5 ] H = 6-2.
0-1530 „ 4-2 c.c. No at 24° and 774 mm. N = 3-l.

C27H0AN requires 0 = 727; H = 6-l; N = 31 per cent.

1622 PYMAN: ISOQUINOLINE DERTVATIVER. PART II.

On leaving this substance in contact with bromine (2 atoms to
1 molecule) in chloroform solution for forty hours, allowing the
chloroform to evaporate, dissolving the residue in a little alcohol,
precipitating it with dilute aqueous ammonia, and crystallising
the precipitate from alcohol, a considerable proportion is recovered
unchanged ; after the evaporation of the alcohol, the residue forms
a 3^ellow gum, which docs not contain bromine.

On attempting to oxidise iY-benzoyl-1 : 2-dihydropapaverine with
dilute sulphuric acid and manganese dioxide under the conditions
previously described for i\^-benzoyltetrahydropapaverine, more than
70 per cent, was recovered unchanged, and no crystalline degrada-
tion products were obtained except a trace of benzoic acid.

1 : 2-Dih7/dro'pa'paverolin e , CjgHjrj04N.

This compound has previously been described by Goldschmiedt
under the name " tetrahydropapaveroline." Comparison of the
colour reactions given here for 1 : 2-dihydropapaveroline and tetra-
hydropapaveroline with those given by Goldschmiedt {loc. cit.)
for his compound indicate that the latter probably contained a
certain amount of tetrahydropapaveroline.

Three grams of 1 : 2-dihydropapaverine hydrochloride (contain-
ing SHgO) were heated with 30 c.c. of concentrated hydrochloric
acid for three hours at 170 — 175°. On opening the tube, methyl
chloride escajoed, and a pale yellow liquid containing pale brown
crystals remained; the latter were collected, and weighed r4 grams,
that is, 74 per cent, of the theoretical.

1 : %'Diliydro'pa'paverolxne hydroc.hloride crystallises from water
in nearly colourless prisms, which decompose at 296° (corr.). This
salt contains half a molecular proportion of water of crystallisation,
and is easily soluble in water :

0-2750 air-dried lost 0-0095 at 120°. HoO = 3-5.

0-1734, dried at 120°, gave 0-3783 COg and 0-0798 HoO. C = 59-5;

H = 5-2.
01530, dried at 120°, gave 0-3349 COg and 0-0689 HgO. C = 59-7;

H = 5-0.
CjpHj504N,HCl,JH20 requires H20 = 2-7 per cent.

CjoHi504N,HCl requires C = 59-7; Hr=5-0 per cent.

This salt readily reduces cold ammoniacal silver nitrate solution,
but does not liberate cuprous oxide from Fehling's solution on
boiling. It gives with ferric chloride a persistent, deep green
colour, and, on the addition of aqueous sodiiim carbonate, dark
flakes are deposited, leaving a violetrcoloured supernatant liquor.

i

SENIER AND COMPTON : THE SYNTHESIS OF ACRIDINES. 162.S

Concentrated solutions of this salt give with alkalis a -white
precipitate, which is sohxblc in excess, giving a pale yellowish-green
solution ; alkaline solutions, however, very quickly blacken on
exposure to air.

T»F. Wkm.comr Ciikmical Works,
DAHTFoun, Kent.

CLXXXIII. — The Synthesis of Acridines : Tetramethyl-
acridines, Dimethyl na2}hthacridines, Na2:)]ithaquin-
acridines, Diquinacridines. ''^

By Alfred Senier and Arthur Compton.

The experiments described in this paper were undertaken with the
object of effecting a linking of two heterocyclic groups, or one hetero-
cyclic and one carhocyclic group, with an acridine nucleus by using the
first and second of the methods described in a previous paper (Trans.,
1907, 91, 1927), and also to extend the work therein reported on the
synthesis of alkylacridines and phenonaphthacridines. We have
succeeded in obtaining a new tetramethylacridine and the correspond-
ing dimethylpheno-a- and -)8-naphthacridines, and by the use of
6-aminoquinoline we have prepared and isolated one di- and two mono-
heterocyclic acridines. The constitution of these bases follows from
their modes of formation, as in the case of simpler acridines and
naphthacridines, and the notation employed is that previously made
use of, adapted in the case of quinoline derivatives to the usual
notation employed for those compounds (compare Senier and Austin,
Trans., 1904, 85, 1196, footnote; 1906, 89, 1387; 1907, 91, 1240).
The positions of the methyl groups in the tetramethylacridine
described are 2:3:7:8, and the phenonaphthacridines are 9:10-
N-a

dimethylpheno - I, ^j „- naphthacridine and 9:10- dimethylpheno -
C H-p

I - naphthacridine of the types represented respectively by

CH-a

diagrams A and ^ in a previous paper (Trans., 1907, 91, 1241).

* The nomenclfitnre is adopted in accordance with that employed in this Journal
for the analogous dinaplithacridines and phenonaphthacridines, notwithstaiiding
that the name qninacridine has been already made use of for compounds of a
different type by previous observers (Niementowski, Ber., 1896, 29, 78 ; 1906, 39,
385 ; Ullmann and Broido, Ber., 1906, 39, 3.57).

1624 SENIER AND COMPTON : THE SYNTHESIS OF ACRIDINES.

The constitution of the quinoline derivatives may be represented
thus :

\/

a-N-6
-Dif|uinaciiiliiie. | -Naplitliaquinacridinc.

5-CH-5 ;3.CH-5

)3-N-6

I
a-CII-5

-Naphthaquinacridine.

In assigning the constitution to the compounds indicated by the
above formula?, it is assumed that the 5-position in 6-amino-
quinoline is more active than the 7-position, and that condensation
takes place there as in the case of the corresponding a-position in
/3-naphthylamine.

I -Diquinacridine is the first known member of a group of
5-CH-5

diquinacridines, of which twenty other members are theoretically
possible, all derived from ordinary quinoline ; and, similarly, sixteen
other isomeric naphthaquinacridines are possible in the group repre-
sented by the two naphthaquinacridines (compare possible dinaphth-
acridines, Senier and Austin, Trans., 1906, 89, 1387).

The fluorescence exhibited in solution by these compounds is
interesting ; the quinacridines showing the phenomena in a greater
or less degree, as was expected from the presence in their molecules
of the acridine fluorophore (compare Meyer, Zeitsch. physikal. Chem.,
1897, 24, 468). The ultraviolet waves, when the bases are dissolved
in the usual organic solvents, are increased in length, showing blue
fluorescence, whilst in solution in glacial acetic acid or in concentrated
sulphuric acid, and in one instance in ethyl acetate, the fluorescence
is green or even yellowish-green. The fluorescence is especially note-

N-/3 . .

worthy in the instances of 9 : 10-dimethylpheno- i ^ -naphthacridine

CH-a

, J8-N-6
and I -naphthaquinacridine.
tt- C H-5

SENIER AND COMPTON : THE SYNTHESIS OF ACIUDINES. 1025

Numerous attempts were made to obtain diquinacridines of other
types, but all without success. Tiius G-amiuoquinoline (2 mols.) or
6-aminoquinoline (1 mol.) and 8-hydioxyquinoline (1 mol.) were heated in
successive experiments with methylene dichloride, methylene di-iodide,
and with formaldehyde; again, 6-aminoquinoline (1 mol.) and 8-hydroxy-
quinoline (1 mol.) were treated with methylene dichloride, methyloiie
di-iodide, and formaldehyde respectively, but the amine alone con-
densed, and diquinacridine was formed. Similarly, in attempts to
prepare a naphthaquinacridine,a-naphthylamine (1 mol.) and 8-hydroxy-
quinoline (1 mol.) could not be condensed with methylene dichloride;
the a-naphthylamine alone reacted, and Senior and Goodwin's dinaphth-
acridine was obtained. Using benzylidene chloride and benzaldeliyde
respectively with a mixture of /3-naphthylamine and 8-hydroxyquinoline

in like manner, only JL„, -dinaphthacridine could be detected.

Several experiments Avere made with a view to the synthesis of
phenoquinacridines, but although some of the results seemed very
promising, they have not yet yielded definite compounds. 8-Hydroxy-
quinoliue (1 mol.) was brought together with «i-4-xylidine (1 mol.) and
o-4-xylidine (1 mol.) respectively, using as condensing agents methylene
dichloride, methylene di-iodide, or formaldehyde, and in the same
manner, 6-aminoquinoline (1 mol.) with o-4-xylidine or m-4-xylidine.

The 2:3:7: 8-tetramethylacridine described was produced from
o-4-xylidine (2 mols.) and methylene di-iodide, the former containing
an alkyl group in a para-position with respect to its amino-group,
which is in accordance with our previous experience (Trans., 1907, 91,
1928).

The work of this inquiry has been unavoidably interrupted, and as
some time must elapse before it can be resumed, it is published in its
present rather unfinished state.

Experimental.
Condensation of o-^:-Xylidine and o-i-Xylenol with Methylene
Dichloride : 2:3:7: 8-Tetramethi/lacridi7ie, CQB^^le.2"^i ^CoR^^^r

o-4-Xylidine (1 mol.), o-4-xylenol (1 mol.), and methylene dichloride
(1 mol.) were heated in a closed tube ; the temperature was allowed to
rise rapidly to 250°, and then slowly to 350°, the higher temperature
being maintained for one hour and a-half . After cooling, the contents
of the tube were well washed with acetone to which some concentrated
solution of ammonium hydroxide was added; by this treatment the base
was left in the form of a nearly white powder ; this was further purified
by washing with methylated spirit, and afterwards with water. The

1626 SENIER AND COMPTON : THE SYNTHESIS OF ACRIDINES.

powder was thfin either crystallised several times from toluene, or
extracted with dilute hydrochloric acid, which yielded the hydro-
chloride in yellow crystals, from which the base was regenerated by
treatment with ammonium hydroxide.

2:3:7: S-Tetramethylacridine crystallises from toluene in clusters
of pale yellow, almost colourless, needles, which melt at 273*5° (corr.).
It dissolves easily in benzene, ethyl acetate, or toluene, sparingly in
acetone, alcohol, or light petroleum. The solution in ethyl acetate
exhibits green fluorescence :

0-2567 gave 0-8154 CO2 and 0-1701 H2O. C = 86-63; H = 7-36.
0-2357 „ 12-2 c.c. Ng (moist) as 11° and 752 mm. N = 6-06.

Ci^H^-N requires C- 86-81 ; H = 7-23; N = 5-96 percent.
Aurichloride, Cj7HjyN,HAuC14. — This salt was obtained as a yellow
precipitate on the addition of a solution of gold chloride to a solu-
tion of the base in a mixture of concentrated hydrochloric and glacial
acetic acids. The precipitate was collected, washed with dry ether,
and dried at 110—115° :

0-0740 gave 0-0252 Au. Au = 34-05.

Cj7HjgNCl4Au requires Au = 34-26 per cent.
Platinichloride, (Cj.j^Hj^,N)2,H.,PtCl^,2H20. — A solution of platinic
chloride was added to a solution of the base in glacial acetic and
concentrated hydrochloric acids. The yellow precipitate, which formed
at once, was washed with glacial acetic acid, then with ether, and
dried at 105°:

0-1347 gave 0-0287 Pt. Pt= 21-30.

Cg^H^oOgNaClfiPt requires Pt = 21-29 per cent.
Salicylate. — This salt was prepared, but not analysed. Tetraraethyl
acridine and salicylic acid were brought together in solution in hot
toluene. On cooling, the salicylate separated in pale yellow needles,
which were purified by recrystallisation from toluene. It is very
soluble in benzene, toluene, alcohol, chloroform, or ethyl acetate, less
so in acetone, and insoluble in ether or light petroleum.

Condensation of o-i- Xylidine with Methylene Di-iodide :
2:3:7: S-Tetramethylacridine.

The same tetramethylacridine as that just described was obtained
by this reaction. o-4-Xylidine (2 mols.) and methylene di-iodide
(1 mol.) were heated in an open vessel for a few minutes until reaction
commenced ; the residue was then well mixed, and allowed to cool.
The viscous, reddish-brown product was dissolved in alcohol, and the
base precipitated from the alcoholic solution by a concentrated solu-
tion of ammonium hydroxide. It was collected, washed with water,

i

RENTER AND COMPTON : THE SYNTHESIS OF AORTDINES. 1627

dried at 100", and then crystallised several times from its solntion in
toluene.

Contrary to previous experience (Senier and Compton, loc. cU.), no
trace of an intermediate diamine could be detected.

Condensation of o-^-Xylidine and a-NapJithol with Methylene Bichloride :
9 : 10- Dimethylpheno- \ -naphthacridine, C^HgMeg^C i ^Cj^H^,.

o-4-Xylidine (1 mol.), a-naphthol (1 mol.), and methylene dichloride

(1 mol.) were mixed and heated in a closed tube for two liourfs, the

temperature being allowed to rise gradually to 220 — -2.30°. After

cooling, the deep red, crystalline product was well washed with

acetone, and the yellow residue of crude hydrochloride was heated to

boiling with alcohol to which a little solution of potassium hydroxide

had been added. The free base deposited as the mixture cooled,

water was then added, and the base was collected and well washed

with water. It was dried first on a porous plate, and afterwards by

heating to 100°, and then recrystallised twice from light petroleum.

N-a
9 :10-Dimethylpheno-^ -naphthacridine consists of pale dull

yellow, thick plates, which melt at 171 — 172° (corr.). It is very
soluble in the usual organic solvents, except alcohol and light
petroleum, in which it dissolves sparingly. Its fluorescence in solu-
tion is noteworthy, being blue when dissolved in benzene, toluene,
alcohol, acetone, ethyl acetate, chloroform, or light petroleum, and
green in glacial acetic or concentrated sulphuric acid. It does not
show triboluminescence :

0-2115 gave 10-3 c.c. N^ (moist) at 18° and 769 mm. N = 5-70.
CjtjHjgN requires N==5*45 per cent.

riatinichloride, (Cj9Hjr;N)2,Hr,PtCl^,,2H20. — This derivative was
obtained as a deep yellow, crystalline precipitate when an aqueous
solution of platinic chloride was added to a solution of the base in
a mixture of glacial acetic and concentrated hydrochloric acids.
The precipitate was washed with glacial acetic acid, then with light
petroleum, and dried by keeping it for two to three days in a vacuum
desiccator :

0-0875 gave 0-01 78 Pt. Pt = 20-34.

CgsnggOaNgClgPt requires Pt = 20-31 per cent.

Aurichloride. — This salt forms a yellow, amorphous powder when
precipitated by a solution of gold chloride from a solution of the
base in a mixture of glacial acetic and concentrated hydrochloric
acids. A specimen was prepared and purified by washing, first with

162S SENIER AND COMPTON : THE SYNTHESIS OF ACRIDINES.

plapial acetic acitl and then with light petroleum. This salt, like the
next following, was not analysed.

Salicylate. — The base (1 mol.) and salicylic acid (1 mol.), both in
hot benzene sokition, were mixed. On cooling, the salicylate separated
as an orange-yellow, crystalline powder. It was recrystallised twice
from toluene or benzene, when it melted at 99 "5° (corr.). It is soluble
in benzene, alcohol, light petroleum, toluene, or chloroform.

Condensation of oA-Xylidine and fi-N^aj)hthol with Methylene Bichloride :

N-/3 . . ^N— >s,

9 : lO-Dimethylpheno- J^ -naphthacridine, CgHqMeg^ ' _^^C,QHp.

A mixtux'e of o-4-xylidine (1 mol.), /3-naphthol (1 mol.), and
methylene dichloride (1 mol.) were heated in a closed tube at a
temperature of 260 — 270" for two hours. The contents of the tube
after cooling, consisting of a dark red, viscous mass, were thoroughly
washed with acetone, and the deep yellow residue was boiled for a few
minutes with a mixture of alcohol and a small proportion of potassium
hydroxide solution. From the solution thus obtained, the free base
was precipitated by the addition of water, and, after several crystal-
lisations from dilute alcohol, was obtained in long pale yellow, almost
colourless, glistening needles.

N-i3
^ :\0-Dimeihyl-)^ii. -naphthacridine dissolves readily in benzene,

acetone, ethyl acetate, chloroform, glacial acetic acid, or concentrated
sulphuric acid, less so in toluene, ether, alcohol, or light petroleum. It
exhibits fluorescence — blue, bluish-green, yellowish-green ; in benzene,
toluene, light petroleum, acetone, ethyl acetate, alcohol, chloroform, or
ether it is blue, and the solutions are colourless ; in glacial acetic acid
it is bluish-green, and the solution is pale yellow ; in concentrated
sulphuric" acid it is yellowish-green, and the solution is deep yellow.
The base melts at 187° (corr.) :

0-1563 gave 7-7 c.c, Ng (moist) at 13° and 750 mm. N = 5-74,
C^fjHjjN requires N = 5"45 per cent.

PlatinicMoride, {Qt~^^^^^)^,^^iQ\Q,2^^0. — This was obtained as a
yellow precipitate on the addition of a solution of platinic chloride
to a solution of the base in a mixture of glacial acetic and concentrated
hydrochloric acids. It was washed with light petroleum and dried at
110°:

0-0570 gave 0-0115 Pt. Pt = 20-17.

C38H3g02N2ClgPt requires Pt = 20*31 per cent.

Aurichloo'ide, Cigll^gNjHAuCl^. — This salt was prepared in the
Bame manner as the platinichloride, using a solution of gold chloride.

SENIER AND COMPTON : THE SYNTHESIS OF ACRIDINES. 1629

The precipitate, which is orange-yellow after washing witli light
petroleum, was dried at 115°:

0-0849 gave 0-0278 An. Au= 32-74.

CjyHjyNCl^Au requires Au = 32-99 per cent.

Salicylate, C■^^y^,Q'~\{^.0^. — The base and salicylic acid were brought
together, both dissolved in hot toluene. From the deep yellow .solu-
tion which resulted, yellow, glistening prisms deposited on cooling.
The compound was recrystallised twice from toluene, washed with
toluene, and dried at 110°. It molts at 164° (corr.) :

0-1042 gave 3-1 c.c. N2 (moist) at 21° and 769 mm. N = 3-43.
C^gHgiOgN requires ISr = 3-55 per cent.

Condensation of G-AininoquinoUne with Methylene Di-iodide or

6-N-6
Methylene Bichloride. _ X,^^ -Diquinacridine,
5- U 11-5

CoHaN<^^>C,H,N.

6-Aminoquinoline (2 mols.) and methylene dichloride (1 mol.) were
heated together in a closed tube for one and a-half hours at 220 — 230°.
The contents were then extracted with methylated spirit, the solution
evaporated to dryness, and the black mass resulting was well washed
with acetone, containing a little solution of ammonium hydroxide,
and then boiled with methylated spirit to which a few drops of solution
of potassium hydroxide had been previously added. After cooling, the
residue, a dark-coloured powder Avhich contained the acridine, was
washed with water, dried at 100°, and the crude base was extracted
with toluene. By successive treatment of the resulting reddish-brown,
crystalline mass with alcohol containing potassium hydroxide and
extraction with toluene, pure crystals were obtained.

By the second method, 6-aminoquinoline (2 mols.) was melted and
methylene di-iodide (1 mol.) added. A vigorous action took place in
a few minutes, and the mixture solidified. The dark-coloured solid
was thoroughly washed with a mixture of acetone and concentrated
solution of ammonium hydroxide, dried at 100°, and extracted with
toluene. A portion which contained halogen remained insoluble, but
was not further examined. The solution in toluene on concentration
yielded an orange-3'ellow, crystalline product. This was collected, and
freed from traces of halogen by boiling for a few minutes withmethylated
spirit to which some solution of potassium hydroxide had been added.
The residue remaining, after cooling, was dried at 110°, and ci-ystallised
several times from toluene.

• ^- Diquinacridine crystallises from dry toluene in clusters

1630 SENIER AND COMPTON : THE SYNTHESIS OF ACRIDINES.

of small needle*, which when dried at llO*^ lose weight and become
lighter in colour, due probably to their having contained com-
bined solvent ; finally, they become bulf-coloured, and melt at
303° (corr.). This compound dissolves easily in benzene, toluene,
alcohol, chloroform, nitrobenzene, aniline, glacial acetic acid, or con-
centrated sulphuric acid ; it dissolves less readily in ethyl acetate or
acetoue ; does not dissolve in ether, and is only sparingly soluble in
light petroleum. The solution in ethyl acetate is yellow, in other
solvents it is colourless. Marked blue fluorescence is shown in
solution in concentrated sulphuric acid. The compound does not
exhibit triboluminescence.

For analysis the substance was dried at 110° :

0-2388 gave 0-7138 CO2 and 0-0848 H^O. 0 = 81-52 ; H = 3-94.

018'J'J „ 24-6 c.c. N.^ (moist) at 13-5° and 748 mm. N= 15-03.
C^gHijNg requires 0 = 81-14; H = 3-91 ; N = 14-95 per cent.

riatiuichloride. — This salt was obtained as a pale pink precipitate
when an aqueous solution of platinic chloride was added to a solution
of the base in a mixture of hot glacial acetic and concentrated
hydrochloric acids.

Aurichloride. — To the base dissolved in a mixture of glacial acetic
and concentrated hydrochloric acids a few drops of solution of gold
chloride were added. A yellow precipitate formed, which was washed
with dry ether and dried at 105°.

Nitrate, Cy^-^-^^,'2'H.'^0^. — This salt was obtained by dissolving
the base in hot dilute nitric acid. After a few hours, pale yellow
needles separated. They do not melt, but soften, and darken at 196°
(uncorr.) :

0-1039 gave 15-6 c.c. ^^ (moist) at 14-5° and 759 mm. N= 17-50.
OjtiHjgOgNg requires N = 17-23 per cent,

Picrute, Q-^^'H.-^^^,{C^.Jd.j^^).^. — Hot alcoholic solutions of the base
(1 mol.) and of picric acid (2 mols.) were mixed. A yellow precipitate
collected, which was washed with alcohol and dry ether and dried at
115°. It is insoluble in light petroleum and toluene, but very slightly
soluble in alcohol. It does not melt below 295°, but darkens in colour
at 278° :

0-1408 gave 0-2579 OO2 and 0-0336 HgO. 0 = 49-95 ; H = 2-65.

0-2005 „ 29-2 c.c. N2 (moist) at 13° and 755 mm. N = 1709.
C31H17UJ4N3 requires 0 = 50-30 ; H = 2-32 ; N = 17-09 per cent.

Bt'itzoate. — This salt was prepared, but not analysed. It formed
readily when hot solutions in toluene of the base and benzoic acid
were mixed and kept for some time. Long, pale yellow needles
separated, which, after recrystallisation twice from toluene, melted at
180-5° (corr,). It dissolves readily in benzene, toluene, alcohol, or

SENIER AND COMPTON : THE SYNTHESIS OF ACUIDINES. 1631

chloroform ; less readily in acetone or ethyl acetate, and is insoluble
in ether or light petroleum.

Salicylate, Cy^\i.-^^.^,{(J^\{^f)^^. — The base (1 mol.) and salicylic acid
(2 mols.), both in solution in hot toluene, were mixed, and the mixture
kept for some time. A buff-coloured precipitate soon commenced to
separate. This was collected and recrystallis^ed several times from
toluene. The salt consists of dull yellow needles, which melt at 216''
(corr.). It does not exhibit triboluminescence. It is soluble in
chloroform, alcohol, ethyl acetate, benzene, toluene, or light petroleum :

0-0922 gave 0-2401 COg and 0-0373 H.p. C = 71-02; H = 4-49.
0-1770 „ 11-8 c.c. N.^ (moist) at 17^^ and 761 mm. N = 7-75.
Ca3H.^30,jN3 requires 0 = 71-05; H = 4-16; N = 7-55 per cent.

Coudensalioit of G-Aininoquinoline and a-XajjIdhol with Mttloyleae
Dichlorlde or Methylene Di-iodide ^ ^ I, ^j i^-^apthaquinacridine,

With methylene dichloride the reaction was brought about in a
closed tube. 6-Aminoquinoline (1 mol.) and a-naphthol (1 mol.) were
heated for two hours at 240°. The contents of the tube were dissolved
by heating to boiling with methylated spirit, and the solution, after
coucontration, was heated with a concentrated solution of potassium
hydi'oxide. A dull green precipitate resulted, which was dried at
100"^ and exti'acted with boiling light petroleum. The solution on
cooling deposited the base as a yellow, crystalline powder. This was
crystallised twice from ethyl acetate.

When methylene di-iodide was employed, the operation was conducted
in an open vessel. The same proportions as before were used. The
base and the a-naphthol were melted together and heated to 120°, and
the methylene di-iodide was added to the mixture. The heating was
continued until a temperature of 130° was attained, when the reaction
commenced and the source of heat was removed until it moderated.
Afterwards, heat was again applied, and the temperature was kept at
170° for (if teen minutes. On cooling, the dark solid was dissolved by
heating to boiling with alcohol to which a little potassium hydroxide
had been added. An inky solution was obtained, to which, when cool,
a small proportion of water was added, which precipitated a dark
powder. This was collected, dried, and extracted with hot light
petroleum, from which solution, on cooling, a yellow, amorphous powder
separated. From this powder the pure base was obtained by recrystal-
lising twice from ethyl acetate.

1632 SENIER AND COMPTON : THE SYNTHESIS OF ACRIDINES.

I -Naphtliaquinacridine crystallises in small, pale yellow

needles, which melt at 268 — 268-5° (corr.). It dissolves readily in
benzene, toluene, nitrobenzene, aniline, chloroform, glacial acetic acid,
or concentrated sulphuric acid, less readily in aftetone, light petroleum,
ethyl acetate, or alcohol, and is insoluble in ether. The solutions are
faintly fluorescout : blue in most solvents, but green in glacial acetic
acid and concentrated sulphuric acid :

0-1846 gave 15-9 c.c. N^ (moist) at 18° and 760 mm. N = 9-95.
CgoHjoNg requires N = 10-00 per cent.

Aurichloride. — This salt was prepai-ed, but not analysed. It consists
of an orange-yellow precipitate, obtained by adding a solution of gold
chloride to a solution of the base in a mixture of glacial acetic and
concentrated hydrochloric acids. The precipitate was washed, first
with glacial acetic acid, and then with light petroleum.

Condensation of (S-Aminoquinoline and (i-N^aphthol with Methylene

/3-N-6

a-CH-5'

Dic/Uoride, Methylene Di-iodide, or Formaldehyde: ^ -Naphtha-

quinacridine, CjQHg\ i x^CgH^N.

Although numerous experiments were made by each of the three
methods, we were not able to obtain this compound in a sufficiently
pure state to give a constant melting point or a satisfactory analysis.

When methylene dichloride was used, the reaction was brought about
in a closed tube heated to 215° for two and a-half hours. With
methylene di-iodide, an open vessel was employed, in which 6-amino-
quinoline and /3-naphthol were melted, and the methylene di-iodide
added. In this case the action was at first violent, and had to be
moderated by cooling, but afterwards the temperature was increased to
140°. With formaldehyde (trioxymethylene), the method was similar
to the last. The products by each method were treated in the usual way
to isolate the base. In all cases, crystals, yellow prisms, were obtained
from light petroleum, benzene, or toluene, which melted about 220°.
The compound dissolves very easily in most organic solvents, less
so in light petroleum or ether. It shows marked fluorescence, which
is blue in most solvents, but green in either glacial acetic or sulphuric
acid :

01 269 gave 0-3963 CO.^ and 0-0502 HgO. C = 85-17 ; H = 4-39.
0-1948 „ 17-2 c.c. N.3 (moist) at 16° and 763 mm. N= 10-33.
0-2538 ., 20-8 c.c. N2 (moist) „ 16° „ 762 mm. N = 9-78.
C20H12N2 requires 0 = 85-71 ; H = 4-28 ; N = 10 00 per cent.

GRAY AND BUKT : THE ATOMIC WEIGHT OF CHLORINE. 1G33

Salicylate, (^oD^iy^.2,Q-j\i,(}^. — Tlie base (I mol.) and .salicylic acid
(1 mol.), each dissolved in hot toluene, were mixed, and the mixture
allowed to cool, when a yellow, crystalline powder quickly separated.
After twice recrystallising from toluene, it melts at 198^(corr.). The
salt dissolves in benzene, toluene, alcohol, acetone, ethyl acetate, or
chloroform, but does not dissolve in ether or light petroleum. Blue
fluorescence is observed in the solutions in alcohol, ethyl acetate,
acetone, or chloroform. The solutions in benzene and toluene are
not fluorescent :

0-0656 gave 3-9 c.c. N.^ (moist) at 16° and 764 mm. N = 696.
^27^18^3^2 requires N = 6'70 per cent.

Univehsity College,
Galway.

CLXXXIV.— T/ie Atomic Weight of Chloriyie,

By Robert Whytlaw Gray and Frank Playfair Burt.

The results of recent researches on the atomic weight of chlorine
furnish a good illustration of the uncertainties inherent in all
atomic weight determinations. The values obtained in any one
investigation agree closely among themselves, and vary regularly
about a mean. The mean values from different methods of experi-
ment, however, are often much more divergent than the errors of
measurement would lead one to expect. The following table
exemplifies these statements, and shows clearly that some of the
values are affected by small constant errors :

Atomic Weight of Chlorine. 0 = 16.

H=^
Obtained by Ratio measured. 1 '0076.

Dixon and Edgar 1 H:C1 35-463

Edgar^ G1:H and CI:HC1 {35.46I

Noyes and Weber 3 H:C1 and H:HC1 35-452

Richards* AgCl:Ag, NH^ClrAgCl,

andAgNOgtAg 35-457

Guye and Fluss 5 01:0 35-466 —

,, ,, Ter-Gazarian" Density of HCl and

critical constants ... 35-461 35-461 —

1 Phil. Trans., 1905, 205, 169. - Phil. Trans., 1908, A, 209, 1.

=* J. Amer. Chem. Soc, 1908, 30, 13. ^ J. Amcr. Chem. Soc, 1909, 31, 6.

5 J. Chim. phys., 1908, 6, 795. " Compt. rend., 1906, 143, 1233.

Since the atomic weight of chlorine is one of the fundamental
values on which the atomic weights of a large number of the
VOL. XCV. 5 P

H =

Probable

1-00787.

error.

35-471

1^:0-0019

35-470

+ 0 0008

35-469

—

35-461

q:0-0008

35-456

very small

1034 GRAY A>JD BLTRT: THE ATOMIC WEIGHT OF CHLORINE.

elements depend, it is of great importance that it should be known
with a high degree of precision. A carefvil examination of the
results of recent investigations by Brauner (Abegg's Handbuch,!!.,
i. 185) has led him to the conclusion that 35'458 is to be regarded
as the most probable value, yet from the figures just quoted it
seems by no means certain that the higher value 35'470 may not,
after all, be a nearer approximation to the truth. In order to
obtain further evidence, we have studied the question from a
physico-chemical standpoint, and the present research contains an
account of the determination of this constant by methods which
are essentially different from those employed either by Dixon and
Edgar, Noyes and Weber, Richards and his colleagues, or by Guye
and Fluss. The work consists of a detailed study of hydrogen
chloride, and falls into three parts, which comprise :

1. A revision of the density of the gas.

2. Its volumetric analysis.

3. A determination of the form of the pv isothermal at 0°,
between the pressure limits 780 and 150 mm.

Part I. — The Density of Hydrogen Chloride.

Comparatively few determinations of the density of this gas have
been made. Leduc {Ann. Chim. Phys., 1898, [vii], 15, 1) deduced
from his experiments the value 1'6407 grams for the weight of a
normal litre of the gas. Later, Guye and Ter-Gazarian {Comft.
rend., 1906, 143, 1233) obtained from four determinations the
mean result r6398, which agrees well with the value 1"6397 result-
ing from six experiments carried out by one of us a few months
later (Proc, 1907, 23, 119). For reasons which will be given
subsequently, we consider the latter value distinctly too large.

In our experiments the gas was weighed after it had been
condensed on cocoanut charcoal. The weighing bulb had a capacity
of about 20 c.c. The bulbs in which the volume of the gas was
measured had a capacity of about 450 c.c. One bulb was made
of soda-glass, and the other of transparent, vitreous silica. The
latter was attached to the rest of the apparatus by means of a
capillary glass-silica connexion, the two portions of the connexion
being cemented together with parafl&n wax. The bulb and con-
nexion were made by Messrs. Johnson and Matthey for this
research.

The method in all particulars is the same as that previously
used by one of us for the determination of the density of nitric
oxide (Gray, Inamj. Diss., Bonn, 1907, " Ueber das Atomgewicht
des Stickstoffs "). The details are best followed from Fig. 1.
A is the volume-bulb, which could be put in connexion either with

GRAY AND BURT: THE ATOMIC WEKJHT OF CHLOHIN'E. 1685

the vessels used for storing aud purifying the gas or witli the
charcoal absorption bulb B. The gas in .1 was kept at 0° by
means of a bath of ice and distilled water. A was filled to a
pressure slightly above atmospheric, and the excess of gas was
allowed to escape through the sulphuric acid gauge GO. Complete
adjustment of the gas pressiire was effected by lowering the flask
// ; the standard barometer was then read, and the stopcock D
turned off. The transference of the measured volume of gas from
A to the weighed absorption bulb B was brought about by slowly
cooling B by means of liquid air, and by opening the taps D and E.
Before this operation was commenced, it was necessary to free

Fig. 1.

the capillary connexion tubes from air. This was accomplished
by a ten minutes' immersion of the second charcoal-bulb G in
liquid air. At the conclusion of an experiment, the absorption
bulb B was detached, cleaned, and suspended from the balance-
beam, and weighed after an interval of an hour. Meanwhile the
empty bulb A was refilled, and the cycle of operations repeated.
After two experiments, the absorption bulb B was heated, and
the condensed gas removed by means of a filter-pump. After
900 c.c. of gas had been absorbed by the charcoal, the pressure
inside bulb B did not exceed a few cm. of mercury at room
temperature, so that an even larger volume of hydrogen chloride
could obviously have been condensed and weighed in the 20 c.c.
bulb.

1636 GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE.

With regard to the actual measurements little need be said. As
can be seen from the following data, the volumes of the two bulbs
were easily determined with a high degree of accuracy by weighing
them full of boiled distilled water in the usual way. The bulbs
were filled with water at 0°, and weighed at room temperature.
A small glass bulb temporarily sealed on to the capillary stem
provided space for the expansion of the water as the temperature
rose from 0° to that of the balance case. A set of weights ranging
from 1 kilogram to 1 milligram was used throughout the research,
and their relative values were ascertained by Richards' method
{^Zeitsch. -physikal. Chem., 1900, 33, 605).

We did not require to know the absolute values of the weights,
since they only served to counterpoise water and gas filling the
bulb under measured conditions. The effect on the density bulb
of a variation in the buoyancy of the air was eliminated in the
usual way by employing a counterpoise. In calculating our results,
all weighings were corrected for the deviation of the face values
of the weights from their true relative values in air, and also for
the air displacement of the weights. In calculating the density
results which we announced in a previous note (Proc, 1908, 24,
215), we made the perhaps not unnatural mistake of assuming that
a correction was necessary for the difl'erence between the air-
displacement of platinum and brass, an assumption which would
have been logical if the original calibration had been carried out
in a vacuum. We overlooked the fact that this adjustment was
made automatically when the weights were compared with each
other in air, and that consequently the same correction for air-
displacement must be made for both metals. This mistake
appreciably alters our final density, and we take this opportunity
of pointing out the existence of an error in the values already
published.

Volumes of the Bulbs at 0°, all corrections made.

Glass bulb. Silica bulb.

1 465-857 c.c. 457-419 c.c.

II. After a three months' ^p'*^'- After heating to

interval 465'855 ,, redness 457-422 ,,

The charcoal absorption bulb B was weighed on a long-beam
Oertling balance, and the probable error of weighing was not
greater than 0'03 milligram. It was counterpoised in the usual
way by a bulb of nearly the same capacity, surface, and mass. On
account of the small volume of this bulb, and the small variation
in internal pressure due to the absorbed gas, the correction for
change in buoyancy on exhaustion was of a negligible order. The

GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE. 1 fi?{7

height of the mercury column of the standard barometer was
referred to a glass scale, and read by means of a telescope and
micrometer eye-piece to 003 mm. The temperature of the
barometer column could be measured to within 0'2°. The absolute
distance between two fixed points on the glass scale was ascertained
for us at the Standards office through the kindness of Major
Macmahon. A second scale used in some of the measurements was
compared with an "invar" meter recently recalibrated at the
National Physical Laboratory. For the loan of this standard,
and for the use of the necessary reading instruments, we desire to
thank Professor Trouton and Mr. Eumorphopoulos, of University
College.

The Preparation of Pure Hydrogen Chloride.

The gas was prepared in three ways :

1. From sulphuric acid and sodium chloride.

2. From sulphuric acid and ammonium chloride.

3. From silicon tetrachloride and water.

The sulphuric acid was prepared by the contact process, and
proved to be very pure. The sodium chloride was prepared by
precipitating from its aqueous solution, by means of gaseous
hydrogen chloride, a very pure sample of the salt obtained from
Messrs. Hopkin and Williams. The sodium chloride was subse-
quently recrvstallised twice from water, and a careful examination
failed to detect traces of other halogens. The ammonium chloride
was purified after the method of Stas (CEuvres compJHen, 1, 373).
The salt was recrystallised twice from water, and the separation
of the mother liquor was facilitated by the use of a centrifugal
machine. The silicon chloride was obtained from Kahlbaum, and
contained no free chlorine and no bromine compounds.

The interaction of the concentrated sulphuric acid and sodiiim
or ammonium chloride was carried out in a high vacuum in a
sealed glass vessel, P, of the form shown in Fig. 1 (Guye and
Bogdan, /. Chim-. Phys., 1905, 3, 537). The salt was introduced
into the lower, and the acid into the upper bulb, and the neck
sealed off with a mouth blowpipe before exhaustion. The gas was
dried by passage over phosphoric oxide contained in the tubes T
in the diagram, and was then condensed to a solid in the vessel 7?.
From 7? the hydrogen chloride was boiled off and condensed in the
second fractionating vessel S ; when the latter was about half full,
the tap was reversed, and the gas allowed to bubble through its
own liquid. In this way any impurities possessing a higher boiling
point than hydrogen chloride were partly or wholly eliminated.
That fraction of the gas which passed over at an early sta^^e of the
operation was judged to be the purest, and was stored for later

1638 GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE.

use in two large 5-litre bulbs, which had been previously evacuated,
first by means of a Fleuss pump, and finally by means of charcoal
cooled ill liquid air. The impure gas was then allowed to
evaporate, and the connecting tubes and fractionating vessels were
freed from this residue with a Topler pump. Before filling the
density bulb, the gas was condensed out of the storage bulbs and
put through another series of fractionations. As a rule, the first
fraction was returned to the storage bulb in case it might contain
traces of air which had been entangled or dissolved in the solid
hydrogen chloride and thus escaped removal by the pump.

The preparation of the gas from silicon tetrachloride necessitated
a different form of generator (Fig. 2). The distilling flask A was
partly filled with distilled water. The silicon tetrachloride was

Fio. 2.

introduced into the cylinder B, which was protected by a calcium
chloride tube from the entrance of moisture. A and B were con-
nected by means of a tube G, which, before the introduction of
water into A, had been filled with dry mercury. During an
experiment the apparatus was immersed in a freezing-bath in order
to moderate the reaction. By slightly reducing the pressure in A,
a small quantity of silicon tetrachloride was sucked over, and the
reaction started. The mixture of air and hydrogen chloride was
passed through a tube D, packed with moistened glass beads, and
then condensed in a large fractionating vessel. The air was pumped
off through the Topler pump, and the hydrogen chloride carefully
fractionated in order to eliminate the last traces of the silicon
tetrachloride.

GRAY AND HURT: THE ATOMIC WEIGHT OF CHLORINE. 1 G39

Zmptirities in the Gas.

Two sources of contamination were discovered in tlie early stages
of the investigation. The gas was found to react with tlie phos-
phoric oxide, forming a volatile phosphorus compound, which was
decomposed by the mercury of the Tbpler pump, a solid yellowish
film being deposited on the glass surfaces. The production of this
compound has already been observed by Richards. When the gas
issuing from the phosphoric oxide tubes was led into water, the
solution gave a yellow precipitate with nitric acid and aqueous
ammonium molybdate. By employing phosphoric oxide distilled
in a stream of oxygen, the formation of this compound was
lessened. It was found, however, that the gas could be freed from
this impvirity by two distillations carried out in the manner
described ; after this treatment, the concentrated aqueous solution
of hydrogen chloride contained no detectable quantity of phos-
phorus.

The action of the gas on the rubber-vaseline lubricant initially
used for the glass stopcocks proved another source of contamination.
The grease was rapidly charred, and the taps soon ceased to
maintain a vacuum. At the same time, organic compounds volatile
in the gas were formed, and the density of the latter increased.
The substitution of metaphosphoric acid for the grease was con-
sidered, but abandoned on account of the large volume of hydrogen
chloride it is capable of absorbing (Baker, Trans., 1898, 73, 422;
Gutmann, Annalen, 1898, 229, 3). Finally, a lubricant, consisting
solely of pure paraffins, was prepared, and this proved to be
without action on the gas and to be capable of rendering a carefully-
ground stopcock gastight for an indefinite period.

After the gas had been kept for some time in the storage bulbs,
it was found to contain traces of chlorine, and to cause phosphoric
oxide to deliquesce. This was doubtless due to chemical action
between the hydrogen chloride and traces of air adsorbed on the
glass surfaces of the apparatus, or given off slowly from the tap-
grease (Berthelot, Coivpt. rend., 1897, 125, 746). To eliminate
the chlorine, the gas was passed over clean mercury before
liquefaction (Shenstone, Trans., 1897, 71, 485). Any mercury
vapour carried by the gas was, of course, condensed in the
fractionating vessels, and could not find its way into the density
bulb.

The crude gas from the ammonium and sodium chlorides and
sulphuric acid certainly contained other impurities. The last
fraction of the liquefied gas nearly always held in suspension a
slight white precipitate, which volatilised less readily than the

1640 GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE.

hydrogen chloride itself. On examination of the gas resulting
from the precipitate, hydrogen sulphide was discovered. Its
presence was evident from the odour of the aqueous solution of
the gas, and also from the formation of methylene-blue in a solution
of 2>aminodimethylaniline sulphate. The mode of its origin is,
however, obscure. It is certain that neither the ammonium nor
sodium chlorides nor the sulphuric acid contained sulphides, and
one can only suppose that it originated from the reduction of the
sulphuric acid itself during the evolution of the gas. The complete
elimination of traces of hydrogen sulphide from hydrogen chloride
is not easy. It might be supposed that it would be removed by
mercury, but mercury does not attack perfectly dry hydrogen
sulphide. Again, it might react with traces of chlorine, but in
view of the absence of moisture this is also doubtful, and, moreover,
chlorine was not always present. For its elimination we had to
rely entirely on the fractional distillation of the liquefied gas.

"With regard to the gas obtained from silicon tetrachloride and
water, it is difficult to see how it could have contained any foreign
gases besides a possible trace of chlorine and vapour of the tetra-
chloride. It was certainly purer initially than the product from
the other two reactions. After the final fractionations, however,
the gas from all three sources was certainly very pure. When
condensed, the liquid was perfectly clear and colourless, and left
no residue on evaporation. On further cooling, the liquid yielded
a pure white, crystalline solid, which melted sharply at a constant
and definite pressure of 100 mm. The gas was entirely free from
air, for a little boiled water or a small piece of solid potassium
hvdroxide absorbed it completely. It contained no compound of
phosphorus, and chlorine was entirely absent. The only likely
impurity, in the case of gas prepared by the action of sulphuric
acid on a chloride, was hydrogen sulphide. For reasons which will
be given later, we are convinced that it could not have been
present in sufficient quantity to influence the density results.

We noticed a curious phenomenon connected with the con-
densation of hydrogen chloride, which is worthy of mention. When
the solidified gas was sublimed, or when the gas itself was slowly
condensed at the temperature of liquid air, the crystalline product
almost always exhibited a rose-pink coloration in patches. On
allowing the solid to become warm, the pink colour entirely vanished
before the melting poinl was reached. We have been unable to
concentrate the coloration by either fractional distillation or
sublimation of the hydrogen chloride. On the supposition that it
is produced by a small trace of some highly coloured impurity, we
have tried to increase its amount by adding small quantities of

GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE. 1641

other gases and vapours, for example, chlorine, iodine, bromine,
nitrogen peroxide, sulphur dioxide, and hydrogen sulphide, to
hydrogen chloride and condensing the mixture, but in no instance
was there any visible increase of the coloration. The phosphoric
oxide was not responsible for its production, for in one set of
experiments sulphuric acid only was used as a desiccating agent,
but the pink colour still made its appearance. It is noteworthy
that Inglis (.7. Soc. Chem. Ind., 1906, 25, 152) obtained a gas
condensing to a red solid from the lead chamber gases of a sulphuric
acid plant. The presence of a trace of moisture prevents the
appearance of the colour, for we were never able to obtain it
unless the gas had been previously very carefully dried. The
intensity of the coloration varied in different specimens, but it
did not appear to influence in any way either the density of the
gas or its volumetric composition. We have, therefore, concluded
that if the pink colour denotes the presence of an impurity, the
latter must have been present in extremely small amount.

Adsorption of Hydrogen Chloride on Glass Surfaces.

In a research of this nature, the adsorption of the gas on the
internal surface of the density bulb calls for carefvil consideration.
We have confirmed the observation of Guye (Convpt. rend., 1906,
143, 1233), that the density of the gas in a new bulb decreases
with each filling, and finally reaches a minimum value which varies
fairly regularly aboiit a mean. In all probability this decrease
is due to the presence on the surface of the bulb of a fi'lm of
moisture which absorbs the gas in relatively large quantities ;
this film being partly absorbed by the charcoal in the weighing
bulb, together with the gas itself, the apparent density is too great.
With each successive filling the film should diminish, and the
density reach a constant value. As a matter of fact, in our method
of working, a limit of desiccation was certainly reached after the
first few fillings, and since, throughout the whole series of experi-
ments in the same bulb, there was never any necessity for
removing the stopcock, any source of error due to the moisture
film either vanished or remained at a minimum. In the absence
of all avoidable moisture there was, however, a small but
appreciable amount of gas adsorbed by the glass.

These conclusions are supported by the following experiments.
A glass cylinder, fitted with a stopcock at either end, was con-
nected with an adjustable mercury reservoir, and completely filled
with dry mercury. On opening the upper tap, carefully dried
hydrogen chloride entered and displaced the mercury; the gas

1642 GRAY AVD BURT: THE ATOMIC WEIGHT OF CHLORINE.

itself was then completely displaced by raising the mercury
reservoir, and the upper tap was closed. On lowering the reservoir
again, a vacuum was produced, and the mercury was drawn down
until the meniscus fell below the lower tap. It was observed that
during this operation small bubbles of gas came off from the walls
of the vessel and collected in the cylinder. On taking special
precautions beforehand to exchide moisture, the quantity of gas
evolved in this way was visibly less. In order to make the experi-
ment more definite, the cylinder was detached from the rubber tube
connecting it with the mercury reservoir, and about 1 c.c. of a
.y/50-silver nitrate solution, acidified w-ith a little dilute nitric
acid, allowed to enter. Care was taken to avoid the presence of
small mercury globules in the cylinder and tubes leading to the
taps. When the cylinder had been carefully dried by a stream
of pure air passed over phosphoric oxide, only a faint opalescence
was produced, but the presence of a very small amount of moisture
was sufficient to cause a marked turbidity in the reagent. Hence
one may conclude that adsorption of the gas by well-dried glass
surfaces is very small. That even this small amount of gas is taken
up by cooled cocoanut charcoal is certain from the fact that on
letting a little of the silver nitrate solution into the exhausted
volume bulb of our apparatus at the end of each series of
determinations, no trace of opalescence was ever observed. This
test was fairly delicate, for blank experiments carried out with the
same volume of silver nitrate solution showed that as little as
2 cub. mm. of the gas could be readily detected.

This last test also negatives the supposition that the glass was
decomposed to any appreciable extent by the hydrogen chloride;
had this been the case, chlorides of the bases present would have
been formed and have yielded a precipitate with aqvieous silver
nitrate.

From the foregoing experiments, it is clear that a rigorous
desiccation of the density bulb was essential if good results were
to be obtained. A silica bulb was used in the later determinations,
for it was very much easier to dry its interior completely. The
silica bulb was heated to redness and repeatedly filled with dry air
and exhausted before attaching it to the apparatus.

In our earlier density measurements, when rubber-vaseline grease
was used as a tap-lubricant, it was only possible to make a small
number of experiments without regreasing the bulb stopcock, and
this involved the admission of moisture. For this reason, and also
on account of the contamination of the gas by the grease, we
consider these results untrustworthy, and they are not recorded
in the final table.

GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE. 1643

In some experiments, whidi will l)e described later, we
have measured the volume of gas removable from the glass surfaces
in a vacuum. The method was similar to that employed in
the qualitative experiments just described, but care was taken to
displace the gas by the mercury at constant pressure. Tlie bulb
was made of the same glass as that used for the densities, and was
kept at 0° throughout the operation. The amount of gas given off
from each square cm. of surface amounted to 0'1235 cub. mm., and
this quantity was constant at constant temperature and for any
given initial pressure. On the assvimption that this adsorbed gas
exerted no pressure, we have made use of these results to correct
our densities. The surface of the density bulb being 291 sq. cm.,
the volume of gas adsorbed by it was 0"036 c.c, ani its weight
0'00006 gram, and hence the amount to be subtracted from the
weight of a litre of the gas was O'OOOIS gram. This correction only
applied to the glass bulb, and since no direct experiments on
adsorption on silica surfaces have been made, we have introduced
no alteration in the measurements carried out in the silica bulb.

Another possible source of error was the solution of traces of
hydrogen chloride in the grease used for the stopcocks. An
attempt was made to measure this. It was found that the amount
of gas dissolved by the grease on the bulb stopcock did not exceed
0"01 CO., and since this amount of gas represents an error smaller
than the mean probable error in any of the series, we have decided
to neglect it.

In the following table we have applied to the numbers in the
third column a small correction for the slight deviation of hydrogen
chloride from Boyle's law betw-een 760 mm. and the observed
barometric height.

Table of Results.

Series I.

Glass bulb. Volume at 0° = 465'856 c.c. Gas from sodium chloride
and sulphuric acid.

Weight of
Weight of 1 litre of gas nt 0° and

gas condcnsi'd Ba rometi'ic pressure 760 mm. in London,

on charcoa.1 : at 0° : London : corrected fcr

all corrections made. all corrections n)ade. compressibility of HC'l.

1. 076097 gram 75676 mm. 1-64053 grams

2. 075731 ,, 753-38 ,, 1-64004 ,,

3. 0-75481 ,, 750-83 ,, 1-64020 ,,

4. 075968 ,, 755-79 ,, 1-63986 ,,

Mean 1-64016 gran, s +0-00010

]64'4 GRAY AND RURT : THE ATOMIC WEIGHT OF CHLORINE.

Series II.

Glass bulb. Gas

from silicon tetrachloride and water.

Weight of

Weight of

1 litre of gas at 0° and

gas condeusod

Barometric pressure

760 mm. in London,

on chn renal :

at 0" : London :

corrected for

all correotions made.

all corrections made.

compressiljility i.f HCl

1. 0-7f)841 gram

754-38 mm.

1-64022 grams

2. 0 7r)959 ,,

755-65 ,,

1-63999 „

3. 0-76169 ,,

757-83 „

1-63976 ,,

4. 0-76150 ,,

757-15 „

1-64083 ,,

fl. 0 75922 ,,

755-14 ,,

1-64030 ,,

6. 0-76186 „

757-79 „

1-64021 „

7. 0-76194 ,,

757-84 „

Mean

1-64027 „

1-64023 grams +0

Series III.

0 00008

Quartz

bulb. Volume

at

0° = 457-420 c.c

Gas from ai

chloride

and sulphuric

acid.

1.

0-74622 gram

756-26 ram.

1-63950 grams

2.

0-74643 ,

75618 „

1-64013 „

3.

0-75295 ,

762-87 „

1-63984 ,,

4.

0 75776 ,

767-31 „

1-64069 „

5.

0-75762 ,

767-35 ,,

1-64031 „

6.

0-75216 ,

761-93 „

1-64017 ,,

7.

0-73831 ,

747-85 ,,

1-64050 „

8.

0-73646 ,

745-99 „

1-64051 ,,

9.

0-74316 ,

752-99 „

1-63992 ,,

10.

0-75651 ,

766-37 „

164001 ,,

Mean 164016 grams +0-00008

From 'the means of Series I and II, there has to be subtracted
0-00013 gram, which represents the weight of adsorbed gas given
off from the walls of the glass bulb. Then the means of the three
series become :

Series I

, II

,, III (unaltered)

1-64003
1-64010
1-64016

The final mean calculated by the method of least squares is
1"64011 +000005, and the weight of a normal litre of gas (namely,
the w^eight of 1 litre at 0° and 760 mm., Lat. 45°) is:

1-64011
1-000588

1 63915 gram,

where 1 '000588 is the factor which expresses the difference in the
value of " g " between London and Lat. 45°.

On comparing the individual values in any one series, it will be
seen that the maximum divergence is very much greater than the
probable errors of measurement. We must say that in view of

GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE. 1645

the concordance of the results obtained by the same method with
nitric oxide, a closer agreement was expected. It hardly seems
likely that the discrepancies can be entirely explained by the
presence of impurities in the gas, and our work on the analysis of
hydrogen chloride supports this view. Moreover, in neither series
is there any progressive change in weight, although the densities
correspond with successive fractions of the liqiiefied gas. On the
other hand, the agreement between the mean values of the three
series leaves nothing to be desired, and in consquence of the large
number of determinations, we think that our final figure is an
accurate approximation to the true density of hydrogen chloride.

Part II. — The Volumetric Aiialysis of Hydrogen Chloride.

In order to deduce the molecular weight of hydrogen chloride
from the value obtained for the density, it w'as possible to adopt
several modes of procedure, involving the knowledge of either the
exact volume of hydrogen yielded by two volumes of the gas, or of
the relative compressibilities of hydrogen chloride and some
standard gas, such as oxygen. A third method was to determine
and reduce the critical constants of the gas according to the
method worked out by Guye (./. C//m. Phys., 1908, 6, 795). These
two latter methods involve a somewhat uncertain extrapolation,
which is not the case in the first method, and for this reason we
thought the most satisfactory course was first to measure accurately
the volumetric composition of the gas.

On account of the deviation of hydrogen and hydrogen chloride
from the gas laws, it is clear that the ratio of the densities at 0°
and 760 mm. does not accurately represent the ratio of the molecular
weights. If, however, the volumes occupied by chemically
equivalent quantities of the two gases are known, the required ratio
can at once be deduced.

The actual course of procedure was to find the volume of
hydrogen obtainable from exactly two volumes of hydrogen
chloride, both gases being measured in the same apparatus at 0°
and 760 mm., that is, the same temperature and pressure at which
the density measurements were made. In essentials the method
was as follows. The two volumes of hydrogen chloride were
measured successively in a constant pressure pipette, which, together
with the mercury manometer column, was immersed in melting ice
throughout the determination. After each filling the gas was
collected in a bulb, and there decomposed by means of heated
aluminium. The hydrogen produced was then returned to the
measuring vessel, and since its volume was a little greater than

Ifjid GRAY AND BUKT: THE ATOMIC WEIGHT OF CHLORINE.

half the total volume of the hydrogen chloride, it was necessary
to increase the volume of the pipette slightly in order to recover
the original pressure. The accurate measvirement of this small
volume increment sujiplied the data for determining the ratio of
chemically equivalent volvimes of hydrogen and hydrogen chloride.

The constant pressure pipette consisted essentially of the thick-
walled bulb A (Fig. 3) of about 300 c.c. capacity, connected below
by means of a short length of capillary tubing with the dead-
space B, and above with another capillary tube carrying a two-way
stopcock C. The dead-space was furnished with a glass point.
The upper chamber of the manometer also carried a glass point,
and communicated with the lower chamber containing the dead-
space as shown in the figure. The distance between the two points
was maintained constant by means of a stout glass rod W, sealed
at its upper end to the manometer head, and at its lower to the
capillary tube connecting the pipette with the two-way tap G.
For our purpose, it was not necessary to know the exact distance
between the two points. It was, however, essential that this length
should not differ much from 760 mm. In sealing together the two
ends of the glass rod when the apparatus was being set up, special
care was taken to ensure the correct adjustment of the two points,
and subsequent measurement with a cathetometer proved the final
distance between them to be within O'l mm. of the required
length. It was further necessary to guard against any alteration
of the vertical distance between the two points during an experi-
ment. The whole apparatus was rigidly fixed to a heavy iron bar
with a tripod base, and any vertical displacement could at once
be detected by the plumb-line VV. By levelling the tripod it was
easy to reset the plumb line, and in practice this could be done
without putting any dangerous strain on the sealed glass connexions.
We adopted the method of Rayleigh (Proc. Roy. Soc, 1893, 53,
137) to ensure the absence of air or moisture in the manometer
head. The vacuum in the latter was verified from time to time
by means of a Topler pump (not shown in figure), and a small tube
containing phosphoric oxide served to retain traces of water vapour.

Sealed to the capillary between the bulb and the tap C was a
capillary T-piece expanding into a tube of a few c.c. capacity,
whicK terminated at its lower end in another capillary carrying a
tap S. During the measurement of the hydrogen chloride, this
side-tube, which we have called the volume-adjuster, was filled with
mercury up to the top. It only came into use during the measure-
ment of the hydrogen, and enabled the necessary increase in volume
to be made.

As can be seen in the diagram, the pipette, manometer column,

GRAY AxNl) BUHT: THE ATOMIC WEIGHT OF CHLORINE. 1647

and volume-adjuster could be surrounded by melting ice contained
iu the tin-baths A' and Z. Ice was always piled up from the lower

Fig. 3.

bath so as to cover the cork Q, in order to keep adjacent parts
of the manometer column and glass connecting rod at 0°. It was
clearly impossible to surround the dead-space with melting ice

1648 GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE.

on account of the difl&culty of seeing the point. To obviate this,
we surrounded the dead-space by a small subsidiary bath U , which
could be filled with a suitable liquid cooled below 0^ by means of
the funnel. For this purpose we used brine, and we found no
difficulty in keeping the temperature within one degree of zero
when the final setting was made. On account of the small volume
of the dead-space (almost exactly 1 c.c), a variation of this order did
not affect the results. The mercury required for displacing gas from
the pipette was contained in a reservoir D. An air-catch T guarded
the pipette from any trace of leakage at the rubber junction.

Calibration of the Fipette. — The pipette was calibrated from
the tap C to the glass point in the dead-space by means of mercury
after the apparatus had been set up, and before the side-tube
leading to the manometer head had been sealed on. For this
purpose a stopcock on capillary tubing, which was drawn out to a
fine point, was temporarily fused on to the glass tubing below
the dead-space. The pipette was then filled with mercury and
cooled to 0°. The whole volume of mercury from the tap G was
run out and weighed. Mercury was introduced again until the
meniscus was set to the glass point, and this quantity was then
run out and weighed. In a second calibration, the required volume
was obtained directly by weighing the mercury run out from the
tap to the dead-space point. During the calibration, the tubing
below the dead-space was wrapped in cotton-wool to prevent the
temperature from changing. The actual temperature in this part
of the apparatus was not of importance so long as it remained
approximately constant. The initial and final temperatures
recorded by a thermometer in the cotton-wool were found not to
vary by more than a degree throughout the operation, a difference
involving no correction on the total volume.

The mercury was weighed in four portions, and a set of
platinised brass weights, ranging from 1 kilogram downwards,
which had been carefully compared with each other, were used
for this purpose. The same set of weights was employed for
weighing the mercury withdrawn from the volume-adjuster in the
measurement of the hydrogen during the analyses. In this way
the volume increment was compared very exactly with the total
volume of the gas, and the accurate evaluation of this ratio was
all we desired to accomplish. The absolute volumes of the mercury
withdrawn could have been calculated by making the usual
corrections for air-displacement, and by comparing our weights
with a standard set, but this was unnecessary, for in no circum-
stances could the required ratio have been appreciably altered by
changes in atmospheric conditions during weighing.

GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE. 1649

Calibration Values.

Temii. of
cotton wool.

I. Weiglit of ineicnry froiii tiip C 4.365 '749 grains 2".')"

,, ,, ,, dead-space point 193'9G8 ,, 29

,, ,, filling pipette from tap

6' to point 4171-781 „ —

Volume 30G-850 CO. —

II. Weight of mercury fruui tap C to dead-
space point 4171 '750 grams 1*2 — 23

Volume 306-848 c.c. —

Mean 30G-849 c.c. —

Introduction and Measurement of the Gas.

The purified gas was distilled into the pipette through the
taps K and C * until the points in B and E were approximately
set. The tap A" was then closed, and the final setting effected by
means of the pressure-adjuster G ; this requires no special descrip-
tion. By arranging the small reservoir ZT at a suitable height, and
swinging the tap .7, minute quantities of gas could be introduced
into or withdrawn from the pipette. By the alternate manipulation
of the pressure-adjuster and of the screw controlling a wooden
clip, which compressed the rubber tubing connecting the reservoir
D to the pipette, the two mercury meniscuses were set to their
respective points. As Lord Rayleigh has shown, this method
enables a very accurate adjustment to be made {Phil. Trans., 1902,
.1, 198,418).

With regard to temperature, the only parts of the system not
actually surrounded by melting ice were the dead-space, which was
cooled in a brine-bath as described, the short piece of capillary
tubing connecting the dead-space and pipette, and the short column
of mercury in the manometer from L to M. On account of a slow
leaking of cold water from the bath above, the temperature of
these portions of the apparatus was reduced nearly to 0°.

When the temperature and pressure had been satisfactorily
adjusted, the tap C was reversed, and the gas allowed to flow
through the capillary tube leading to the previously exhausted
decomposition bulb M. This bulb carried a silica boat slung from
two stout platinum electrodes by means of silver leads; the boat
was surrounded by a spiral of 30 per cent, iridium-platinum wire,
which could be heated to redness by an electric current. The boat
contained small pieces of pure aluminium.

In order to obviate the use of a ground joint necessitating a

Both the taps C and K, through which hydrogen chloride passed, were lubri-
cated with the paraffin grease described on p. 1639.

VOL. XCV. 5 Q

1650 GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE.

lubricant, the boat and its attachments were sealed up in the bulb
before the latter was fixed i?i situ. When the two volumes of
hydrogen chloride had been transferred, mercury was taken
through the tap C and along the capillary as far as the bulb.
During decomposition, the capillary leading to the pump was kept
filled with mercury, previously introduced through the side-tube Y.
This served to confine the hydrogen chloride to the bulb, and also
to protect the lubricant of the tajD 0 from the action of the gas.
We might mention here that in our final experiments no gas but
pure hydrogen was ever allowed to pass the taja 0 leading to the
pump.

After decomposition, the resulting hydrogen was allowed to flow
back through the tap C into the pipette, and the remainder taken
through the pump into the collector P, which was sealed to the
inverted end of the capillary fall-tube. From time to time the
hydrogen in the collector was allowed to return by the capillary
tube R to the pipette. As has already been indicated, the recovery
of the original presure was effected by running out mercury from
the tap S, and so increasing the pipette volume. This volume
increment was then accurately measured by weighing the mercury
run out.

Decomposition of the Hydrogen Chloride.

The selection of a suitable metal for the decomposition of
hydrogen chloride was a problem of some difficulty. Those metals
forming chlorides reducible at a red heat by hydrogen were clearly
unsuitable. For the process to take place readily, it was necessary
that a clean metallic surface should always be exposed to the
gas. To ensure this, the resulting chloride had to be either fusible
or capable of being sublimed, or the metal had to be in the liquid
state so that it could be agitated during the process.

Preliminary trials were made with the following metals :
magnesium, tin, sodium amalgam, and, lastly, aluminium. With
magnesium, the reaction did not start easily, and, once started,
was quite uncontrollable. Molten tin reacted more gently, but
with the dry gas the reaction did not proceed to completion. In
the case of sodium amalgam, no decomposition whatever occurred
unless the reaction vessel was appreciably moist. Even on raising
the temperature to about 200°, the bright surface of the amalgam
remained untarnished. In carrying out the reaction in presence
of moisture, the hydrogen yield was too small. This probably is
to be attributed to the fixation by the sodium hydroxide of a
portion of the water, which did not then react with the amalgam.

Experiments with aluminium gave far more satisfactory results.
Whilst there was no reaction in the cold, at dull redness and in

GllAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE. 1651

entire absence of moisture decomjjosition proceeded steadily and
rapidly to completion. We therefore selected this metal for our
final analyses.

The aluminium employed was a very pure specimen obtained
from the British Aluminium Company. Analysis showed that it
contained no carbon, a trace of iron, and only O'l per cent, of
silicon. As is well known, aluminium electrodes, when subjected
to the electric discharge in a vacuum tube, evolve hydrogen in
appreciable quantities. The metal we used evolved a relatively
small quantity of this gas, but the evolution was slow, even at
bright redness in a vacuum. In order to reduce this content of
hydrogen to negligible pi"oportions, the silica boat and metal were
kept at a high temperature in the evacuated bulb for several hours
before a series of experiments was begun. Finally, the temperature
was raised, and the aluminium just fused, which ensured the
expulsion of the last traces of the gas. The silica boat was prac-
tically unattacked by the fvised aluminium or by the subsequent
treatment it underwent in the decomposition bulb, and its weight,
even after a series of experiments, was hardly altered.*

During decomposition, the chloride volatilised as it was formed,
and was deposited as a colovirless, crystalline sublimate on the
walls of the bulb, which were kept cold by a stream of water. The
resulting hydrogen, when slowly bubbled through a silver nitrate
solution, proved to contain no trace of hydrogen chloride. If,
however, the aluminium chloride was first resublimed by heating
the walls of the bulb, the hydrogen pumped off undoubtedly con-
tained traces of the original gas. This showed that a certain
quantity of hydrogen chloride had been retained by the sublimate ;
this occluded gas could not be pumped off, but was expelled during
volatilisation. To eliminate this source of error, the aluminium
chloride was sublimed in a vacuum after the main bulk of the
hydrogen had been removed, and the small quantity of hydrogen
chloride liberated was then- decomposed by reheating the aluminium.
This process was repeated until no more gas could be obtained.
The final glowing served also to expel any gas which might ^have
been taken up by the platinum-iridium wire on cooling in hydrogen
at a high pressure.

In the earlier expex'iments, a wire of pure platinum was used
for heating the boat, but we found that owing to the action of
the aluminium vapour the wire fused after a short time and the
circuit was interrupted. Renewal of the wire required the breaking
and resealing of the end of the bulb, and caused much delay. By

* Original weight of boat 4 6715 grams "i x

M'eight aftei seven experiments 4-6712 „ 1^°^^ P^''" "&T '

„ nine more experiments. 4-6710 „ J 0 00003 gram

5 Q 2

1652 GRAY A\D RURT: THE ATOMIC WEIGHT OF CHLORINE.

the employment of a wire containing a high percentage of iridium,
drawn for ns by Messrs. Johnson and Matthey, this difficulty was
overcome. Frequent openings of the bulb entailed other dis-
advantageous consequences. The admission of moist air, even when
no aluminium chloride was present, invariably led to irregular
results, doubtless on account of the difficulty of drying the glass
surfaces before • the actual decomposition was begun. For this
reason, sufficient aluminium for a series of determinations was
introduced into the bulb at the start, and, with proper precautions
to eliminate moisture, concordant values were usually obtainable
after the first analysis.

From the foregoing description, it can be seen that in this
apparatus the errors of measurement of the volume of the gas
were reduced to a minimum. There was no appreciable uncertainty
in the temperature of the manometer column, and the pressure
was constant within the small limits defined by the accuracy with
which the mercury surfaces could be set to the two points. The
internal diameter of the glass tubing of which the reading portions
of the manometer were constructed was about 15 mm. The capillary
depression was consequently very small, and its influence on the
pressure setting must have been quite negligible on account of the
method of adjustment of the meniscuses. Further, it was repeatedly
proved that the gas could be circulated through the apparatus
and retransferred to the pipette with hardly any perceptible change
in volume. Before the final determinations recorded in this paper,
we spent more than two months in testing the apparatus. We
frequently made the experiment of passing a measured volume
of hydrogen prepared from hydrogen chloride into the decom-
position bulb, heating the aluminium for a long period, and then
measuring the gas again in the pipette. In absence of moisture,,
the two measurements never differed by more than one part in
ten thousand, and in many cases a concordance of one part in
twenty thousand was attained. In the actual analysis of hydrogen
chloride, many unforeseen sources of error made their appearance,
and these will now be briefly considered.

Impurities in the Hydrogen Chloride.

In discussing the purity of the gas with which the density
determinations were made, we pointed out that a rigorous frac-
tionation of the liquefied hydrogen chloride was necessary in order
to remove traces of hydrogen sulphide from gas generated from
sulphuric acid and a chloride. The results of the volumetric
analysis indicated still more clearly the need of the same precaution,
since an amount of this impurity, insufficient to affect the density,

/

GRAY AND BUKT : THE ATOMIC WEIGHT OF CHLORINE. 1653

had a marked influence on the vohime ratio. That we finally
succeeded in eliminating hydrogen sulphide is shown by the fact
that nefirly identical results were obtained by analysis of gas from
silicon tetrachloride and water, and from phosphoric acid and
ammonium chloride, sources which admitted of no possible con-
tamination with this impurity.

Although the gas prepared from silicon tetrachloride and water
had given excellent density results, a fresh preparation for the
volume ratio apparatus was not so satisfactory. The difficulty of
separating by fractionation some impurity the nature of which we
were unable to determine soon led us to discontinue experiments
with this particular sample of gas. From the lower-boiling
fractions, we obtained one result which w'e have included in our
final series, but the higher-boiling fractions gave values differing
from each other by as much as one part in 2500, and were hence
neglected. It was judged sounder to check our results by the
analysis of gas from a fresh source rather than prepare another
sample from silicon tetrachloride and water. Accordingly, we
selected the interaction of phosphoric acid and ammonium chloride
as likely to yield a pure product. The phosphoric, acid (Kahlbaum,
sp. gr. 1*7) contained no sulphates, no organic matter, no lower
acids of phosphorus, and only a small trace of nitric acid, as shown
by the brucine test. The ammonium chloride was a sample of
very pure salt supplied by Merck, and contained no organic bases.
It was recrystallised twice from boiling water, and the perfectly
clear solution was then evaporated to dryness in the flask in which
the reaction was afterwards carried out. The greatest care was
taken to avoid the entrance of dust or other organic impurities.
No corks were used, and evaporation was effected by the passage
of a stream of pure dry air over the surface of the solution while
the flask was heated on a water-bath. When the salt was perfectly
dry, phosphoric acid w^as introduced, the neck of the flask sealed
off, and the side-tube fused on to the rest of the apparatus. The
reaction, which was carried out in a vacuum, proceeded steadily
on gentle warming. The residue left in the flask after the reaction
was always perfectly white. From its method of preparation, this
specimen of hydrogen chloride must have been very pure. The
liquefied gas, however, was subjected to the same series of distil-
lations before storage as the less pure gas from other sources, and
was fractionally distilled into the pipette immediately before
analysis.

Among the list of impurities already discussed, we should include
traces of sulphur dioxide and carbon dioxide, which might have
been formed by the action of sulphuric acid on dust particles in

1654 GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE.

the reaction vessel. The existence of the former of these gases —
which would have been easily separated by fractionation — is incom-
patible with that of hydrogen sulphide, small quantities of which
were known to be present in the early stages of purification. Owing
to its physical and chemical properties, traces of carbon dioxide
would have escaped recognition or separation, but the presence of
appreciable quantities would certainly have been detected, as the
density and the volume ratio results would have been affected in
opposite senses. Assuming that the carbon dioxide would have been
completely reduced by the aluminium in the decomposition bulb,
the volume ratio would have been low, whereas the density would
have been high. The following table shows the effect of 0"1 per
cent, by volume of various impurities on the density and volume
ratio respectively :

Pure liydrof;en chloride.

O'l per cent. H.,S

0"1 ,, air

0-1 „ SiCU

0-1 ,, CO2

0-1 ,, SO2

0-1 ,, HBr

Volume of hydrogen

from two volumes of

Deusity.

hydrogen chloride.

1-6392

1-0079

1-6391

1-0089

1-6383

1-0085

1-6423

1 -0069

1 -6396

1-0069

1-6405

1-0069

1-6412

1-0079

It is easy to see that most impurities would have changed the
results of the volumetric analysis and the densities in opposite
directions and by different amounts. The fact that constant values
for both sets of measurements were obtained with gas from different
sources furnishes the best criterion of its purity and of the accuracy
of our final numbers.

Adsorption of Hydrogen Chloride on the Glass Surfaces.

This phenomenon has already been discussed in Part I. A
correction was made for the gas adsorbed on the walls of the density
bulb and subsequently removed by the charcoal. In the same way
the displacement by mercury of the hydrogen chloride from the
pipette in the volume-ratio apparatus left on the walls a layer of
adsorbed gas, which had to be taken into account, for had it not
been removed it would certainly have escaped from the walls when
the bulb was filled with hydrogen. In this case, however, it was
unnecessary to measure and allow for this gas, since it could be
got rid of without difficulty. In order to avoid any variation in
the quantity of gas adsorbed, each volume of hydrogen chloride
was transferred from the pipette to the decomposition bulb at
approximately constant pressure. This was achieved by a suitable
regulation of the tap C and of the position of the reservoir D, and

GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE. 1655

by carrying out the decomposition of the first volume of hydrogen
chloride before the introduction of the second. As soon as the
second volume of gas had been displaced, the tap G was shut and
the reservoir D lowered. The adsorbed gas escaped from the walls
into the vacuous pipette, and on taking the mercury up again
was collected in the capillary. From here it was removed into the
fractionating train by forcing the mercury through the other bore
of the tap 6'. By repeating this operation twice, the adsorbed gas
was reduced to a negligible quantity. In most experiments we
adopted the further precaution of washing out the pipette with
hydrogen from a previous determination.

Impurities in the Hydrogen.

The purity of the hydrogen obtained from the volume analysis
was tested in various ways. The gas had no odour, and, as has
already been mentioned, contained no trace of hydrogen chloride.
The absence of hydrocarbons was proved by exploding with oxygen,
when no carbon dioxide was found. Traces of silicon compounds,
such as silicon tetrachloride, silicochloroform, or silicon hydride,
might conceivably have been derived from the small quantity of
silicon in the aluminium. Of these, silicon tetrachloride or silico-
chloroform would have been detected in the same manner as
hydrogen chloride when the hydrogen was bubbled through silver
nitrate solution. Silicon hydride, being very unstable, would hardly
have escaped decomposition in the bulb. Further, on exploding the
hydrogen with oxygen, any silicon compounds present would have
left a residue of silica, and this was never observed.

In order to test for the presence of nitrogen, about 150 c.c. of the
hydrogen were exploded with pure oxygen, vmtil the volume was
reduced to less than 1 c.c. This residue, after being dried over
phosphoric oxide, was taken into a vacuum tube and examined
spectroscopically. At low pressures no nitrogen could be detected,
and there was only a very faint indication of its presence when
the pressure was raised. This amount was negligibly small, and
could not have influenced the results.

Numerical Results.

Since the volume, pressure, and temperature of the hydrogen
chloride and the pressure and temperature of the resulting hydrogen
were fixed and constant, the weight of the mercury run out of the
volume-adjuster was a direct measure of the increase in volume, no
corrections being required.

IGoG

GRAY A\n HURT: THE ATOMIC WEIGHT OF CHLORINE.

Volume of Hydrogen Chloride, 306-849 x 2 c.c. in all cases,
of Hijdrofjen, 306-849 + a; c.c.

Yohnne

Weight of

Volume of

mercury

Increment

hydrogen from

run out

volume X

two volumes of

Source of g;us.

(in grams).

(in c.c).

hydrogen chloride

NaCl and H.vSO^ ...

Exp. 1

33-25

2-446

1 00797

NaCl and H^SOj ...

2

33-16

2-439

1-00795

NH4Cland H.,S04...

','. 3

32-98

2-425

1 00790

NH4Cland H.^SO^...

,, 4

32-97

2-425

1-00790

NH.Cland H;S04...

• 1 J>

32-57

2-396

1-00781

SiCl^andHoO

,, 6

32-50

2-390

1-00779

XH4CI and HgPOj...

)» "1

32-85

2-416

1-00787

NH4CI and H3PO4...

„ 8

33-30

2-449
I\Iean

1-00798
1-00790

Maximum deviation,

1 in 5000.

Probable error,

+ 0-000017.

We now have all the requisite data for calculating the atomic
weight of chlorine.

If Z>Hci represents the weight of a litre of hydrogen chloride at
0° and 760 mm., Lat. 45°, and B^ represents the weight of a litre
of hydrogen under the same conditions, and if the ratio of the
volumes of hydrogen and hydrogen chloride, which at 0° and
760 mm. contain equal number of molecules, is denoted by E, then
the molecular weight of the gas in terms of 0 = 16 is given by the
expression :

Atomic weigiit of hydrogen.

Assuming Morley's value for the weight of the litre of hydrogen
under standard conditions, namely, 0-089873 gram, and also his
value 1-00762 for the atomic weight of this element on the oxygen
standard, the molecular weight of hydrogen chloride is obtained on
substituting our experimental values in the above expression :

1-63915

0-089873 1-00790

1 -00762 = 36'467.

and the atomic weight of chlorine = 35-459.

This value is in close agreement with the values found by Dixon
and Edgar, namely, 35-463, and by Edgar, 35461, who also based
their calculations on Morley's atomic weight of hydrogen, but
differs by 1 part in 3500 from that found by Noyes and Weber,
namely, 35-452, whatever value is assigned to hydrogen. It should
be pointed out here that our result, unlike Dixon and Edgar's, is
dependent not only on the atomic weight, but also on the density
of hydrogen. We have selected Morley's value for this constant
as being the most trustworthy, and our selection seems justified by

OKAY AXD BURT: THK ATOMIC WEIOHT OF CHLORINE. 1657

the results of the measurement of the compressibility of hydrogen
chloride which we now proceed to describe.

Part III. — The Go7npressihilities of Oxyr/en and Hydro(jen Chloride

It has been shown by D. Berthelot and Raylcigh that at
sufficiently low pressures all gases should strictly follow Boyle's
law, and that their relative densities should be exactly proportional
to their molecular weights. The actual measurement of gaseous
densities at low pressures is unnecessary, for the normal densities
can be reduced to the corresponding values for perfect gases from
a knowledge of the gaseous compressibilities. Thus, if D^ represents

the normal density of a ga^, and A■^^ the mean coefficient of com-
pressibility between 1 and 0 atmosphere.';, then D.i I - /Ij^ ) repre.sents

the density the gas would have under normal conditions if its
behaviour on compression from very low pressure to 1 atmosphere
were theoretically perfect. That is to say, the ratio of the molecular
weights of different gases is exactly equal to the ratio of the
densities :

D,{\ - A,l) : ^,(l - J,^) : D,(l - J^J), etc. '

The compressibility coefficient represents the deviation per
atmosphere of a gas from Boyle's law between the pressure limits
0 and 1 atmosphere, and is defined by the expression :

^^ Po'"o{Pi-Po)'
where v^Vq represent the volumes occupied by the same mass of gas
under pressures PpPo' ^^ constant temperature. The densities

Z)j( 1 - yljp. |, DJI - A.2r.), etc., are called by 1). Berthelot limiting

densities.

The variation of gases from Avogadro's law may be conveniently

expressed in terms of density per unit pressure. If the weight of a

certain mass of gas is W grams, and if it occupies at 0° a volume

V litres under a pressure of 2^ atmospheres, its density per unit

pressure is W/pv. The value taken by this expression when ]) = 1

atmosphere represents the normal density, and the value when p

is very small, the limiting density. At pressures intermediate

between 0 and 1 atmosphere the same mass of gas will occupy the

volumes Vj, rg, and v^, and exert the pressures p^, po, and p^, and

the densities per unit pressure will be :

WW , IF
, , and

Pi'"i P2P1 Pi"z

1058 GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE.

For a perfect gas it is clear that these values will be eqiial, for
■pv is independent of the pressure, but for those gases which are
more compressible than theory demands, j;?' increases as the pressure
falls and the density per unit pressure diminishes. On the other
hand, for gases like hydrogen and neon, the converse is true, and
the limiting densities are greater than the normal densities.

The ratio of the limiting densities of two gases in this terminology
is:

where ITj and 11"^ represent any weights of two different gases in
grams, and p\v\, plvl the values in litre atmospheres of the corre-
sponding pv products of these weights at very low pressures.
Consequently, if the molecular weights of the two gases are repre-
sented by J/j and Mo, and the molecular weight Mo is known, the
value of il/j is given by the expression :

IF,

2^,2

It is, therefore, evident that the measurement of the exact
molecular weights of gases by the method of limiting densities
resolves itself into the accurate determination of the factor PqVq.
The whole jDroblem, then, is to determine with the necessary pre-
cision the variation of pv between the pressure limits 0 and 1
atmosphere.

There are two ways in which pv can change with changing
pressure. The variation per unit pressure may remain constant
down to very low pressures, or the variation oi pv may decrease.
It is, however, very difficult to decide experimentally whether
dpvjdp ever becomes zero, because as the pressure falls the
measurement of p becomes less and less accurate. At very low
pressures a gas may apparently obey Boyle's law; that is to say,
if the volume be doubled, the pressure may appear to be exactly
halved, but on account of the slight absolute change of p, the
variation of pv may escape detection. For this reason, it is difficult
to say from the researches of Rayleigh on the behaviour of gases
at low pressures whether dpvjdp remains constant from one
atmosphere dov/n to very low pressures, or whether its value
decreases as the pressure falls. All methods of determining the
value of PqV(^ involve an extrapolation from regions where pv
measurements are experimentally practicable. It is, therefore,
essential to determine the lie of the pv isothermal in these regions
as exactly as possible. In making the necessary extrapolation in
order to calculate the exact molecular weights, most investigators
have assumed either that jji; is a linear function of p between the

GRAY AND HURT: THE ATOMIC WEIGHT OF CHLORINE. 1659

limits 1 and 0 atmospheres, or that the slight curvature of the
isothermal can be calculated from theoretical considerations (Guye,
J. Chim. iihys., 1908, 6, 769, and D. Berthelot, " Sur les Ther-

Fk;. 4.

^

n

mometres a gaz "). The first assumption is very probably correct
for the permanent gases, but for the more compressible gases, such
as hydrogen chloride, the true form of the isothermal can only be

IGUO GRAY AND HURT: THE ATOMIC WEIGHT OF CHLORINE.

satisfactorily ascertained by the experimental determination of a
large number of points. In their researches on the compressibilities
of ammonia and sulphur dioxide, Jaquerod and Scheuer made only
three measurements of ^^r at pressures of 800, 400, and 200 mm.
respectively, and extrapolated to zero pressure by means of a
parabolic formxxla. The values they obtained in this way for the
molecular weights of the two gases were distinctly too low, and
it seems possible that the true form of the isothermal escaped
recognition on account of the small number of points.

Another factor which has been neglected by all investigators in
this connexion is the variation in the amount of gas adsorbed by
glass surfaces with varying pressure. In the present investigation
we have endeavoured to settle as accurately as possible the qjv
isothermals of oxygen and hydrogen chloride by determining a
large number of points, and in the case of hydrogen chloride we
have taken into account the adsorption effect.

A series of pressure and volume measurements were made
between the jiressure limits of 860 and 150 mm. Our results for
oxygen confirm those of previous investigators, and show that the
isothermal at 0° is a straight line within the limits of measurement.
In the case of hydrogen chloride, the isothermal shows a distinct
curvature, which becomes more marked as the pressure decreases.

The apparatus (Fig. 4) consisted essentially of a bulb A, con-
nected with a dead-space B and manometer C. The effective volume
of the bulb A could be varied by withdrawing mercury from the
tap D. The bulb, which was made of thick glass, had a capacity
of about 550 c.c, and was filled with mercury to a mark E on
the capillary immediately above the dead-space. The pressure
contraction of the bulb was measured by completely exhausting it,
filling it with mercury cooled to 0° to a mark on the capillary
stem, and then determining the change in volume with changing
pressure by the movement of the meniscus along the graduated
capillary. The results were expressed in a graph, from which the
necessary volume correction for any given pressure could be read.

E xfcrimental Numbers.

Volume to be subtracted

Pressure. from volume of gas.

760 mm. 0-000 c.c.

600 ,, 0-006 ,,

550 „ 0-008 ,,

350 ,, 0-014 ,,

40 ,, 0-02.5 ,,

At the end of the compressibility measurements, we made experi-
ments to see whether the weight of mercury in the bulk caused any

GRAY AND HURT: THE ATOMIC WKIOUT OF CHLORINE. 1661

distortion involving alteration of volume. This was done by
weighing out mercury and at the same time sucking in water
through the upper capillary. The volumes corresponding with the
successive quantities of mercury removed were compared with the
volumes of water weighed in. Only a very small and negligible
alteration in volume due to distortion was observed.

The dead-space and manometer were made from carefully selected
lead glass barometer tubing, which had an internal diameter of
about 17 mm. The use of lead glass tubing, on account of its
freedom from bubbles and striae, allowed the position of the
meniscus to be determined with very great accuracy. In making
the dead-space, special care was taken to avoid heating the glass
immediately opposite the point. After many unsuccessful attempts,
a dead-space possessing a volume of only 1"275 c.c. was obtained,
and when it was placed in front of a glass scale and viewed through
a low power microscope, no distortion of the scale lines in the
vicinity of the point could be detected.

Dead-space and manometer were immersed in a bath with two
plate glass sides, and a stream of water kept the temperature
constant. Inside the bath and immediately in front of the
manometer column was suspended a glass millimetre scale, to which
the distance between the two mercury meniscuses was referred.
The scale, which was 1200 mm. long, was made by the Societe
Genevoise. The lines were of the order of 0'002 mm. in thickness,
and required careful illumination to render them visible. For
measuring fractions of a millimetre, we used a telescope fitted with a
Hilger micrometer eye-piece, which enabled an accuracy of O'Ol mm.
to be obtained. The length of scale over which readings were
taken (960 mm.) was compared with an " invar " standard, and
found to be 0044 mm. too long at 16°. The scale was further
calibrated in 30 mm. lengths by means of a reading microscope
and standard screw reading to 0"001 mm., and a table of deviations
drawn up. The maximum correction for irregularity of the scale
was 003 mm.

Experimental.

The oxygen was prepared by heating pure potassium per-
manganate, and was jDurified and dried by passage over soda-lime
and phosphoric oxide. It was finally liquefied and distilled into
the bulb. The hydrogen chloride was prepared and purified in
the way already described. Before the final filling, the bulb was
repeatedly exhausted and washed out with the gas to be experi-
mented with. It was then filled with mercury rather beyond the
mark E on the capillary above the dead-space, and the whole cooled
to 0°. The gas entered the dead-space through the side-tube G,

166iJ GRAY AND HURT: THE ATOMtC WEIGHT OF CHLORtNE.

aud when the pressure had risen to atmospheric, the final adjustment
of the meniscus to the mark on the capillary was made by means
of the tap D. By making this final adjustment at atmospheric
pressure we obviated the necessity of applying a correction to the
original volume of the gas for the contraction of the bulb on
exhaustion. The next step was to allow mercury to run out of the
tap D into a weighed bottle // until the effective volume of the
bulb was of the required magnitude. The quantity of gas in the
bulb and dead-space could then be adjusted, so that when the
mercury meniscus was set to the glass point the pressure was of the
order desired. By working in this manner, the initial volume of
the gas was given directly by the volume of the mercury at 0°
withdrawn from the bulb, plus the volume of the dead-space.

Before reading the pressvire of the imprisoned gas, we waited
for some time after the temperature of the water in the manometer
bath had ceased to vary. After a constant temperature gradient
had been attained, there was usually a small difference of the order
of 0"1° between the water surrounding the dead-space and the water
at the top of the bath. The temperature of the water was ascer-
tained by means of two thermometers, K and L, inside the bath, one
fixed close to the dead-space point, and the other adjustable to the
level of the ujoper mercury meniscus. At low pressures the ther-
mometers showed an almost perfect agreement, since they were
closer together. The temperature of the bath remained constant for
long periods, and since the inean temperature was certainly known
to within 0"05°, the maximum error on the length of the mercury
column due to uncertainty of temperature was less than 001 mm.

The reduction of the temperature of the bulb and its contents
to 0° was necessarily slow, but by observing whether the mercury
meniscus in the dead-space remained set, it was easy to see
when equilibrium had been established. To avoid uncertain
correction, that part of the capillary tube which was outside the
bath, and connected the bulb and dead-space, was also immersed
in melting ice contained in a metal gutter.

Before making a pressure reading, the mercury meniscus in the
dead-space was always brought exactly in contact with the point
by means of a screw clamp compressing the rubber tubing con-
necting the reservoir P with the dead-space and manometer column.
The distance of a line on the scale from the set meniscus was
verified immediately before and after each reading, as it was found
that the position of the scale was subject to minute variations.
Except that we always adjusted our mercury meniscus exactly to
the glass point, our method of reading was the same in all par-
ticulars as the method described by Travers, Senter, and Jaquerod

GRAY AND RtJRT: THE ATOMIC VVEIOIIT OF CHLORINE, 1663

in their research on the coeflicieuts of expansion of helium and
hydrogen. On account of the relatively large diameter of the
mercury meniscus, the point and its mirror image were visible
through the telescope, so that an exceedingly accurate setting was
possible; further, the correction for capillarity was reduced to
negligibly small dimensions.

The initial pressure having been determined, successive quantities
of mercury were withdrawn from the bulb and weighed, and the
pressures corresponding to the new volumes read. As can be seen
from the diagram, mercury would cease to flow from the tap 1)
after the pressure in the manometer had fallen to about 500 mm.
At this stage, mercury was withdrawn by attaching the side-tube
of the small flask // to a filter pump. When nearly all the mercury
had been removed from the bulb, the process was reversed, and
a series of readings taken with rising pressure.

The results in the following table are stated with all corrections
made. The latter comprise :

For volume.

1. Reduction of the volume occupied by the gas in the dead-
space to 0°.

2. Contraction correction of the bulb.

3. Reduction of the apparent weight of mercviry to the vacuum
standard.

For 'pressure.

1. Correction for the total error in the scale at the temperature
of reading.

2. Correction for irregularity of ruling in the scale.

3. Reduction of the corrected manometric height to 0°.

In order to show how the corrections were applied, we append a
full calculation of the results of one experiment taken at random
from our note-book.

Oxygen.
Series I.

p (ill mm.).

V (in c.c).

pv.

Smoothed pv.

763 •.^■2

182-864

139620

139629

711-07

196-373

139635

139638

612'56

227-980

139651

139656

564-46

247-440

139670

139665

499-93

279-400

139680

139677

447-18

312-393

139696

139687

384-52

363-300

139696

139696

348-83

400-456

139691

139705

313-57

445-585

1397-22

139712

284-77

490-603

139709

139717

1664

GRAY AND

V.VWY: TtlK

A'lOMlC WEIGHT

OF nn.oKiKE.

Series II.

p (ill mill.).

r (ill ('.('.).

pv.

Smoothed ;i)('.

87r.-99

158 -Gil

138942

138940

849-32

163-605

138953

138945

826-60

168-100

1^8956

138949

77809

178-587

138957

138956

738-03

K^8-304

138974

138962

690-64

201-212

138965

138970

609-03

228-204

138983

138983

560-45

248-010

138997

138992

515-32

269 ■7-24

138994

139000

409-56

339 -420

139013

139018

372-85

372-842

139014 .

139024

337-27

412-177

139015

139031

309-58

449-115

139037

139035

280-52

495-651

139040

139040

266-73

541-616

139049

139044

Se?

ies III.

866-99

64-874

56245

56249

785-76

71-597

56258

56255

607-97

92-570

56280

56267

547-05

102-863

56271

56272

488-03

115-302

56271

56276

426-36

131-996

56278

56280

365-61

153-959

56289

56285

322-83

174-367

56291

56288

282-72

199-102

56290

56290

252-53

222-920

56294

56293

2-26 -33

248-730

56295

56294

204-30

275-575

56300

56296

188-54

298-563

56291

56298

185-87

302-916

56303

56298

171-66

327-945

56295

50-Z99

169-39

332-375

50301

56299

157-48

357-468

56294

56300

Calculation of ^u' at 0° from experimental results (last in
Series III).

Volume of Gas.

Volume of gas in bulb at previous reading, all

corrections made 328-807 c.c.

Weight of mercury run out 373-25 giams

Correction for air displacement of mercury ... +0-03 ,,

373'28

Increase in effective volume of bulb ,„ ^^.tt = 27-456 ,,

13-59o5

Volume of dead-space 1-275 c.c.

Temperature of gas in dead-space 11-00°

T 1 <. • T , ^o 1 -275x273 _ -i.ox-
\ oluine of gas in dead-space at 0 „„ — i ^-^o ,,

Contraction of volume of bulb under dimin-
ished internal pressure, namely, 158 mm. -0021 ,,

Total volume occupied by gas at 0" 357-468 c.c.

GIIAV AND HfMtT: I'llK ATOMIC WKKJHT OK CJf (.OIIIN p:. 1 ()<)5

I'rcssurc of Gas.
Lowir Meniscus. — Mean of two series of readings taken before and

after reading upper meniscus :

Distance from niciciii\' inenisous set to
point in dcad-siiace to stiile-liue 5-
above it

Micrometer

readings. Millimetre.
92, 89, 89, 91, 070
91, 89, 89

Mean =: 90
(128 micrometer
divi.sions = l mm.)

Scale
readings.
5-00 -0-70

= 4-30

U'pper Meniscus

Distance of upper meniscus below scale-)

line 163 /

Uncorrected manometric height

163-00 -0-88
= 102-12
-82 mm.

Correction for total error in scale

157
+ 0

-0
-0

007

007
021

320

111, 113, 112 0-88

Mean = 112
162-12-4-30
0-044x158

960 ~

Contraction of scale from 16° to ir 0-000009x5x158 =

Correction for irregularity of scale ruling =

Correction of observed manometric height
from 11-05° to 0" =

Corrected manometric height = 157 '48 mm.

Therefore, ;;i- = 157-48 x 357-468 = 56294.

The experimentally found values of fv for each series were
plotted on squared paper on an open scale against the corresponding
pressures, and it was found that the points were evenly distributed
about a straight line. Various lines were ruled, until one was
obtained which was judged to approximate most closely to the
positions of the largest number of points. The deviations of the
points from this line were read off and summed. This process was
repeated, if necessary, with a fresh line until the algebraic sum
of the deviations approached zero. From the final line the smoothed
values for fv given in column 4 were obtained. From the table
it can be seen that, although a few of the points diverge ajopreciably,
yet the majority deviate only slightly from the smoothed values,
and the position of the final line, on account of the number of
points, is fixed with a high degree of accuracy.

From the three series, the corresponding values of p^^'o ^-nd
/J,?', are readily obtained:

Series,

139769

139087

56311

139628

138959

56256

The limiting densities are given by the expression :

W

Dr.., =

/'o^o

VOL. XCV.

5 R

1G66 GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE.

where II' equals the weight of gas in grams, and p^)V^^ is expressed
in litre-atmospheres.

But ir=^"''"' • ^^^^ where Z>„o,.,„ is the weight of a litre under

standard conditions, p^v^ is in litre-atmospheres, and Pi = l. Substituting

i),j_^ _ norm. • Pi'''\^ which is independent of the units in which pv is

expressed, the limiting density of oxygen, assuming for the weight
of a normal litre, lat. 45°, the value 1'42900 grams_^ is:

Series 1 1-42756

„ 2 1-42768

,, 3 1-42760

]\Iean, taking into account the number

of observations in each series 1-42762

» The compressibility coefficient Al from each series is :

Series 1 -0-001009

„ 2 -0-000920

„ 3 -0-000977

Mean -0-000964

The pv measurements in the case of hydrogen chloride were
obtained in a precisely similar way to those just described, but
in calculating out the results, a further correction was applied for
adsorption of the gas on the walls of the bulb. The maximum
volume of gas adsorbed at 0° and 760 mm. was determined in the
bulb itself, which for this purpose replaced one of the glass cylinders
shown in Fig. 5. Afterwards the variation of the quantity of gas
adsorbed with varying initial pressure was measured in the
apparatus about to be described, and these experiments, in con-
junction with the experiment in the bulb, enabled the requisite
corrections for all pressures to be applied to the compressibility
measurements.

The principle of the method was to expose the surface of a dry
glass cylinder to hydrogen chloride at a definite temperature and
pressure, and then to displace the gas at constant pressure by
mercury. The adsorbed gas remained on the glass below the
surface of the mercury, and was subsequently removed by lowering
the mercury and producing a Torricellian vacuum in the cylinder.
Finally, the volume of the adsorbed gas was measured in a
capillary tube.

The apparatus (Fig. 5) consisted of two cylinders, A and B, of
about 300 sq. cm. internal surface, connected with each other
through a two-way stopcock C. The cylinders could be filled with
mercury from the reservoirs 7J and E, which were attached to a

GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE. 1667

cord running over the pulleys G and //. This system of adjustment
enabled one to transfer the gas from one cylinder to the other at
constant pressure. The cylinder ]i wjis not used in the measure-
ments, and merely served as a reservoir for the collection of the
displaced gas. The measuring cylinder A was surrounded with
ice and water contained in a tin-bath, and the capillary tube K,
which was carefully calibrated,
was used for the measurement of
the volume of the adsoi'bed gas.

Before the hydrogen chloride
entered the apparatus, the
greatest care was taken to
ensure the complete absence of
moisture. The gas was left in
contact with the glass for twenty-
four hours, and then displaced
into the cylinder B at constant
pressure. The tap C was then
turned off, and a short length
of the mercury thread in the
calibrated capillary was frozen
by means of solid carbon dioxide
contained in the paper vessel L.
This was necessary, because the
gas dissolved in the grease of
the tap, and was afterwards
slowly evolved in a vacuum.
The mercury was next lowered
so as to produce a vacuum, into
which the adsorbed gas escaped.
On allowing mercury to refill
the cylinder, this gas was col-
lected and measured in the
capillary, and was afterwards
removed through the tap C.
The mercury thread was then frozen again, and by repeating the
operations described, a further quantity of gas was collected
and measured. This process was continued, allowing definite
intervals of time for the adsorbed gas to accumulate, until
the volume obtained became negligibly small. The measured
volumes of gas were afterwards plotted against the times during
which the surface remained exposed to a vacuum. By making
measurements at different pressures, we obtained a series of curves
from which the total volumes of gas adsorbed at various pressures

5 u 2

1668 GRAY AND BURT: THE ATOMIC WEIGHT OF CHLORINE.

could be read. The logaritlims of these volumes were finally plotted
against the corresponding pressures, and the corrections to be
applied to the volumes in the compressibility measurements were
read from the curve so obtained.

Variation of Adsorption with Pressure.
Experiments in cylinder A ; surface 300 sq. cm. T = 0°.

Volume of adsorbed

Pressure.

gas at 0° and 760 mm

0

0-0000

218 mm.

0-0034 c.c.

;u7 ,,

0-0045 ,,

•"^47 „

0-0070 „

730 ,,

0-0104 ,,

The experiments in the bulb yielded for the same initial pressure
a larger volume of gas per unit area. This was almost certainly
due to a difference in the state of the surface of the glass, since
the other experimental conditions were the same. The total
quantity of gas adsorbed at a pressure of 782 mm. of mercury and
at 0° was 0047 c.c, and the surface was 320 sq. cm. In correcting
our results, we have ado23ted the value obtained in the bulb itself,
and for low-er pressures we have multiplied the values from the
cylinder experiments by a factor to correct them to this standard.

It should be stated here that experiments on the amount of
adsorption of hydrogen and air were also made in this apparatus.
With hydrogen the amount of gas adsorbed was barely detectable.
Air was adsorbed to a greater extent, but the value obtained was
very much smaller than that in the experiments with hydrogen
chloride. These results are of interest, since they show that the
gas was really adsorbed and not imprisoned in minute cavities in
the glass surface.

Before correcting the results, one other factor had to be taken
into account. Since the quantity of gas adsorbed is directly pro-
portional to the surface, it was necessary to know how the surface
of the bulb exposed to the gas varied as the mercury was with-
drawn. Por this purpose, we assumed that the bulb was spherical,
and we calculated the surface for the corresponding volumes. The
nature of the correction will be clear from the following figures,
taken from the correction table in our note-book: .

Pressure of gas.

Surface of
glass exposed.

Yoluiiie of adsorbed
gas at 0" and at observed
yjrcssure : to be added to
measured volume of ga.e.

829 mm.
314 „
158 „

68 sq. cm.
122 „
193 „

0-0098 c.c.
0-0172 ,,
0-0.341 „

\

GRAY AND BURT: THE ATOMIC WEIGHT OF CHLOKINE. 1669

As the glass surface increased and the pressure fell, the absolute
amount of gas adsorbed also increased, since the surface effect more
than counter-balanced the effect of diminishing pressure. The
actual alteration of the form of the curve on applying this
correction was very small.

The following table of results for hydrogen chloride is given with
all corrections made :

Hydrogen Chloride.

(in mm.)-

V (in c.c.)

829-50

66-012

761-09

72-023

734-65

74-626

720-78

76-072

604-71

90-815

558-67

98-334

515-35

106-642

468-21

117-432

424-66

129-5'J5

384-13

143-259

347-70

158-343

314-29

175-233

289-39

190-331

264-53

208-286

243-40

226-401

223-95

246-117

207-68

265-447

193-41

285-016

180-24

305-898

157-57

349-978

pv.

Smoothed pv.

54757

54757

54816

54802

54824

54820

54831

54829

54917

54903

54936

54932

54958

54958

54983

54986

55004

55010

55030

55034

55056

55054

55074

55072

55080

55084

55098

55097

55106

55107

55118

55116

55128

55125

55125

55132

55135

55138

55146

55148

On plotting jjv against the corresponding pressures on the same
scale as the oxygen, we found that a line drawn through the points
had a slight but distinct curvature, which was more marked in the
low pressure region. That is to say, the variation of -pv per unit
pressure decreases as the pressure falls, and the rate of decrease
is greater at lower pressures. It seems probable that a compressi-
bility curve of this type may be characteristic of all gases which
at 0° lie below their critical points, and, if this is so, D. Berthelot's
principle, when properly applied, should give as accurate results
for the liquefiable as it does for the permanent gases (Guye,
J. Chim. phys., 1908, 6, 792).

In drawing the most probable line through the points, exactly
the same procedure was followed as in the case of oxygen. Two
points in the high pressure region were obviously inaccurate, and
less weight has been assigned to them than to the other points. On
account of the slight curvature, extrapolation to zero pressure
seemed at first sight an uncertain process. Afterwards, when the
general lie of the curve had been fixed by means of a spline, graphic
extrapolation over the comparatively short length' of 157 mm. gave
values for J)^^v^^ differing only slightly from each other. After many

1670 GRAY AND BUllT : THE ATOMIC WEIGHT OF CHLORINE.

trials, we decided that the fairest extrapolation was obtained with
the curve cutting the fv axis at 55213. The value of fiV-^, also
taken from this curve, proved to be 54803, so that the value given
by the results for

W'o is ^^^ = 1.00748,
p^v^ 54803

and the limiting density of hydrogen chloride is

-^■^' • ^1^1 = L^^915 ^ J. 52698 grams per litre at 0° and 760 mm.
P^Vq 1 -00746 ^ ^

The molecular weight of hydrogen chloride in terms of oxygen
is, therefore,

Aim. hydrogen chloride on _ l"62698x32 _ o/?.j^/.q
Aim. oxygen 1-42762

and the atomic weight of chlorine, 36-469- 10076 =35-461.

If the validity of the assumption underlying the principle of
limiting densities be admitted, this result affords valuable con-
firmatory evidence of the correctness of the atomic weight of
chlorine obtained by volumetric analysis. The two values, 35-459
and 3o'461, only differ by 1 part in 18,000. They both depend,
however, on the density of hydrogen chloride, and any uncertainty
in it would affect them equally. The former value, as is evident
from the method of calculation, is further influenced by any error
which would change the ratio atomic weight of hydrogen : density of
hydrogen, but the latter number is practically independent of
the O : H ratio, for the molecular weight of hydrogen chloride
yielded by the compressibility results is expressed directly in terms
of the oxygen standard. The close agreement is mainly brought
about by the concordance of the results of the volumetric analysis
and those of the jpv measurements. Thus, if 4-000054 be taken
as the coefficient of compressibility of hydrogen per atmosphere at
0° (the mean of the results of Rayleigh, Jaquerod, and Scheuer
and Chappuis), the ratio of the volumes of hydrogen and hydrogen
chloride containing equal numbers of molecules is :

1+0-00054

1-0 00748

= 1-0081,

whilst volumetric analysis gave 1-0079.

The final value for the atomic weight of chlorine yielded by these
investigations is, therefore,

35-460. 0 = 16.

GRAY AND HURT: THE ATOMIC WEIGHT OF CFILORIXE. 1671

An arithmetic mean of all recent determinations (0 = 16;
H = r00762) gives the same result.

Dixon aiul Edgar 35-463

Edgar 35-461

Noyes and Weber 35-452

Richards and colleagues 35 457

Guye and Fluss 35-466

Guyc and Ter-Gazarian 35-461

Gray and Burt 35 460

Mean 35-460

Consequently, it may be stated with a considerable degree of
certainty that the higher numbers which result from the use of
Noyes' value for the atomic weight of hydrogen, namely, r00787,
are distinctly too great, and that the value advocated by Brauncr
is a close approximation to the true atomic weight of chlorine.*

In conclusion, we desire to express our appreciation of the kindly
interest Sir William Ramsay has taken in the research, and to
thank him for his advice and criticism. Also we wish to thank
Mr. H. S. Patterson and Mr. H. Page, who analysed some of the
samples of aluminium, and Mr. W. N. Morley and Mr. A. C.
Dunningham, who helped us in some of the compressibility measure-
ments.

Part of the expense of the work was defrayed by a grant from
the Royal Society, and we here record our indebtedness to the
Government Grant Committee, without whose assistance this
investigation could not have been made.

Univkrsity College,
London.

* Durii'g the correction of the proofs of this paper, a research by Scheuer on the
density of hydrogen chloride has appeared {Compt. rend., 1909, 149, 599).
According to this he obtains for the weight of a normal litre of the gas the
value 1-6394 grams. This only differs from our present figure, namely, 1-6392
grams, by 1 part in 8000. Possibly this small discrepancy may be due to the
different method employed by us to correct for the gas adsorbed by the walls of
the bulb.

We have already referred to the error affecting the results which we published
in a preliminary note (Proc, 1908, 24, 215).

1672 JONES: SPONTANEOUS CRYSTALLISATION OF SOLUTIONS

CLXXXV. — The Spontaneous Crystallisation of Solutions
of Sodium Carbonate and Sodium Thiosulphate.

By Beknaed Mouat Jones.

During the investigation of tlie spontaneous crystallisation of
solutions of sodium sulphate (Hartley, Jones, and Hutchinson,
Trans., 1908, 93, 825), it was found that if crystal nuclei were
excluded, and the solutions of varying strengths cooled down slowly
with constant shaking, the unstable hydrate, NaoSO^jTHoO, nearly
always appeared. The production of this solid phase was very
regular, and the conditions determining its appearance were exactly
defined by the supersolubility curve that was traced for it. The
work recorded below was undertaken in order to determine whether,
in the case of salts which form several hydrates, the spontaneous
production of the unstable form, when supersaturated solutions
are slowly cooled and shaken, is a general phenomenon. The salts
chosen for the investigation were sodium carbonate and sodium
thiosulphate, both of which crystallise from aqueous solutions with
amounts of water of crystallisation which vary according to the
conditions.

I. — Experiments on Sohttions of Sodhnn Carbonate.

Five solid phases may crystallise from solutions of sodium
carbonate, namely, ice, Na2CO3,10H2O, Na2C03,7H20 (ortho-
rhombic), Na2C03,7HoO (rhombohedral), and Na2C03,H20. The
supersolubility curves (that is, the curves giving the temperature of
spontaneous crystallisation of supersaturated solutions of
varying strengths) have been traced for ice, Na2CO3,10H2O, and
NaoC03,H20. The crystallisation of Na2COo,7H26 (orthorhombic)
was irregular and of rare occurrence, giving but a slight indication
of a supersolubility curve in the case of this solid phase. The
crystallisation of the rare rhombohedral Na2C03,7H20 was not
observed at all.

The method of experiment was precisely similar to that used in
previous investigations on sodium sulphate (Hartley, Jones, and
Hutchinson, loc. cit.) and on some alkaline nitrates (Jones, Trans.,
1908, 93, 1739). "Weighed amounts of pure anhydrous sodium
carbonate and distilled water were sealed up in glass tubes con-
taining angular fragments of Jena glass to promote friction. The
tubes were then warmed in a bath until all traces of crystalline
nuclei had disappeared. Care was taken not to warm the tubes
to too high a temperature, in order to avoid the production of the

OF SODIUM CARBONATE AND SODIUM THIOSULPHATE. 1673

monohydrate which might act as a nucleus for the growth of one
of the other hydrates. When it was certain that no solid salt
remained in the tube, it was cooled down with constant shaking
by hand in a well-stirred water- (or alcohol-) bath, the temperature
of which was falling at the rate of about one degree in twenty
minutes. The temperature at which crystallisation occurred was
noted on a thermometer graduated in tenths of a degree, and stan-
dardised against a thermometer with a National Physical Labora-
tory certificate. Several determinations were made with each tube.
After one preliminary determination with the temperature of the
bath falling rather more rapidly, the remaining determinations
rarely differed by more than one or two tenths of a degree. The
highest temperatures at which crystallisation was observed for
solutions of varying strengths are given in the tables below, and
are plotted as supersolubility curves in the figures. In all cases
the determinations were made as soon as possible after the sealing
of the tube, in order to minimise the effects of the chemical action
of the alkaline liquid on the glass. From the concordance of the
results, it was evident that the amount of action was very small
in tubes which had only recently been made up. In tubes which
had been prepared some weeks, particles of silica could be seen in
the liquid, and such tubes were not used in plotting the sujoer-
solubility curves.

C rystallisation of Ice. — This was an extremely definite
phenomenon. The temperature of spontaneous formation of ice
could generally be foretold to 0'1°. Very violent shaking did not
seem to cause crystallisation at temperatures appreciably higher
than those recorded with moderate shaking. Distilled water,
cooled under exactly the same conditions as the sodium carbonate
solutions, gave ice crystals at — 07°. This temperature is rather
higher than that previously found by the author, — 1"2° (loc. cit.).
The rate of cooling, however, in the present instance, was rather
slower. The temperature observed by Miers was — 0'4°, and by
Hartley, Jones, and Hutchinson, — 0'5°. The small difference
between these values and the value —07° recorded in the present
paper is probably due to the solvent action of the water on the
glass fragments enclosed within the tube. These fragments become
broken up by the continual shaking, and the very small particles
of glass produced in this way are doubtless acted on by the water
fairly rapidly, and lower slightly the temperature of the spontaneous
production of ice. The value —05° was obtained by using garnets
in place of glass fragments; Miers used "glass, garnet, galena, or
lead." The use of glass as an agent to produce friction, then,
probably introduces a slight constant error of not more than one

l()7-i JONES: SPONTANEOUS CRYSTALLISATION OF SOLUTIONS

or two tenths of a degree into all the determinations. At the
same time, its itse is not attended with the disadvantages arising
from crystallised substances, such as garnets or galena, which may
have some inoculating effect, the extent of which it might not be
possible to gauge, and which might vary for different solutions.

The highest observed temperatures of crystallisation of ice from
dilute solutions of sodium carbonate are given in table I. They

Frc. 1.

ffi Crystallisation of ice.

O ,, ,, NajCOa.lOH.^O.

A ,, ,, "S a, fiO^jlQY^^O in the labile region.

X „ ,, Na2C03,7H20.

are plotted as the ice-supersolubility curve in Fig. 1. It is seen
that this curve runs nearly parallel to the ice-solubility curve at
an average distance from it of about one and a-half degrees.

Table I.

(The tube contained from 18 to 44 grams of solution.)

Parts of NajCO., in
100 parts HoO...

Temp, of crystal-
lisation of ice ...

0-0 1-50 5-.31 10-26 1.3-5;i IG-.'iO 16-57 18-46
-0-7' -1-3" -3-1° -5-0" -6 1° -6-6° -7-Q" -7-5

OF SODIUM CARBONATE AND SODIUM TIIIOSULPHATE. 1675

Two anomalous cases were observed, for which no explanation at
present seems forthcoming. The tube of concentration 10"26 gave
crystals of ice on slow cooling at — 5'15° and — 5"05°. In the third
experiment, crystals of Na^.COgJOILO were produced at — 5*0°.
On dissolving these, and cooling down again, ice appeared as before
at — 5'05°. Attempts to produce salt again from this tube were
not successful.

The tube of concentration 16"o7 showed an even more curious
behaviour. The supersolubility curve indicated that ice should be
formed at about —7°. A preliminary rather rapid experiment
gave crystals of Na2CO3,10HoO at —7-5°. A second slow experiment
produced ice at —70°; but on removing the tube from the bath
the ice melted, and salt suddenly appeared. Subsequent experi-
ments with this tube gave salt always between — 4'8° and — 6'0°.
Ice was never again produced in this tube. Repetition of the
experiments on the same tube two months later produced salt at
about — 7°, but in this case there were obvious signs that con-
siderable chemical action had taken place in the interval. Another
tube of nearly the same concentration, 16'50, was prepared. This
behaved normally, always giving ice at about — 6'6°.

Cri/stallisation of NaoCOgjlOHoO. — -

Table II.

(The tube contained from r5 to 5"5 grams of solution.)

Temperature of

Parts of Na.^

CO,

crystallisation of

ill 100 parts HoO.

Na.3CO3,10H.,O.

19-27

-6-6°

23-01

6-0

20-24

5-3

22-26

3-0

23-87

2-0

28-09

2-0

2.0-09

0-7

28-34

-I-0-6

32-57

2-0

30-56

2-6

32-03

3-4

34-71

4-0

Parts of NaX'Os
in 100 parts H 26.
39-28
35-38
34-23
36-38
37-20
38-95
39-58
42-42
44-92
47-30
47-98

Temperature of

crystallisation of

Na.3CO3,10H2O.

+ 4 9°

5-0

5-1

5-3

5-9

6-2

6-5

7-2

7-7

8-0

8-4

Table II shows the highest temperatures at which supersaturated
solutions of sodium carbonate, on slow cooling and constant shaking,
would deposit crystals of the decahydrate. In cooling such solu-
tions, it was nearly always the decahydrate which appeared; the
spontaneous formation of the heptahydrate was only rarely observed
— in all, eight times in five tubes, out of a total of more than
100 crystallisations in which salt was produced. The regularity
of the crystallisation of the decahydrate is indicated by the super-

1676 JONES: SPOXTAXEOUS CRVSTALLISATIOX OF SOLUTIONS

solubility curve traced in Fig. 1, which determines the lower
temperature limit of the metastable region for this solid phase. In
no case did crystallisation of the decahydrate take place appreciably
within the metastable region as defined by this curve — except in
the two anomalous cases mentioned above. In a few cases, however,
marked A on the diagram, it was necessary to cool the tubes a
few degrees into the labile region before crystallisation would take
place. The tubes for w-hich this was necessary showed always a
slightly anomalous behaviour. The tendency to crystallise seemed
rather sluggish, and a longer time was necessary before crystal-
lisation could be induced to take place. It is possible that in these
tubes the glass fragments had been attacked to a greater extent
by the alkaline solution than in the case of the normal tubes. In
every abnormal case, when another tube was prepared of nearly
the same concentration, the new tube behayed normally, the solution
crystallising at the temperature required by the supersolubility
curve. When crystallisation of the decahydrate occurred, it
appeared to start from a few, generally one or two, points, which
might be on the inner surface of the glass, or, less usually, in the
interior of the solution itself. The crystallisation, having once
started, proceeded with great velocity, the whole solution at once
beccjning solid.

The supei'solubility curve for NaoCO3,10H2O is seen from the
figure to lie roughly parallel to the solubility curve at an average
distance from it of 25 degrees. It cuts the supersolubility curve
for ice at a temperature of — 7'6°, corresponding with a concen-
tration of 18'7; this is the " hypertectic " point for ice and
decahydrate.

Crijstallisatinn of NaoC03,7H20. — As mentioned above, the
appearance of this solid hydrate was of rare occurrence, and a
tube which would give it once would not necessarily give it again.
The highest observed temperatures of crystallisation of this phase
are given in table III :

Table III.

(The tube contained from 29 to 41 grams of solution.)

Parts of Na.X03 in 100 parts HoO 27-11 34-71 35-38 36-00 37-20

Temp, of crystallisation of Na.jCO:j, 7 H/J. 1-9° 5-0" 4-3" 4-9° 6-5°

The first tube seems to have been abnormal. Crystallisation of
the heptahydrate was observed once only at a much higher tem-
perature than was anticipated, and the observation could not be
repeated. Nor could the decahydrate be induced to appear even
at temperatures well below 0°. Omitting this tube, it appears that
there is a tendency to produce the heptahydrate only between

OF SODIUM CARI'.ONATE AND SODIUM THIOSULPHATE. 1677

narrow limits of conceutralion — 34'71 and 3720. Even l)el\veen
these limits, however, the tendency to form the decahydrate was
just as marked, the ratio of the number of crystallisations of
heptahydrate to that of decahydrate being 8 : 7.

The crystallisation temperatures of the heptahydrate, shown on
the figure thus : X, give a slight indication of the existence of a
supersolubility curve for this hydrate, running nearly parallel to
the solubility curve, but the crystallisation was not sufficiently
regular or definite to make this certain. The opposing tendency
among the solute molecules to produce the decahydrate appears
to make the determination of the metastable limit for the hepta-
hydrate a matter of some uncertainty.

The formation of the heptahydrate was characterised by the
sudden production of a great number of small crystals, giving the
solution a milky appearance. The production of this " labile
shower " in the case of the heptahydrate was in marked contrast
with the sudden solidification of the solution on the formation of
the decahydrate.

Crystallisatio7i of NaoCOgjHoO. — This hydrate is less soluble in
hot than in cold water; hence it is necessary to heat a saturated
solution freed from crystal nuclei in order that crystallisation may
take place. Owing to the negative temperature-coefficient, and to
the fact that the solubility curve at higher temperatures becomes
almost parallel to the temperature axis, the rate of adjustment of
equilibrium in such a solution is extremely slow\ The observation
of the spontaneous formation of crystals was then in this case a
more tedious and difficult matter. It was found necessary to use
platinum tetrahedra to promote friction instead of glass fragments,
since the latter on breaking up gave rise to minute particles
indistinguishable from the crystals of the monohydrate. These
latter, when first formed, were without definite outline, sharp edges,
or bright facets, but were irregular, rounded, glassy particles,
showing no distinctive characters under a pocket-lens. This fact
rendered their immediate detection a matter of some difficulty.
The lowest temperatures at which spontaneous crystallisation was
observed in tubes of varying strengths are given in table IV.
These temperatures are probably not accurate to less than one
degree.

Table IV.
(The tube contained from 23 to 4 grams of solution.)

Parts of Na.,C03 i" 100

rarts HoO " 49-06 48-23 47-72 46-90 46-52 45-34 45-30

Temp, of crvstallisation of

NaoCO..,HoO 54-5° 58-0° 60-0° 04-0° 69-5" 81-0' 827°

1678 JONES: SPONTANEOUS CKYSTALLlSATloN OF SOLUTIONS

The results are plotted in Fig. 2, and give rise to a supersolubility
curve w'Licli at higher temperatures is almost coincident with the
solubility curve.

II. — E xperiments on Solutions of Sodium Thiosulphate.

Sodium thiosulphate has long been known as a salt which readily
gives rise to strongly supercooled solutions or fusions. It is, further,
a salt which foi'ms a number of different solid hydrates, and so
was considered suitable for the present investigation. The crystal-
lisation of supercooled fusions of this salt has been made the
subject of an exhaustive study by Young, Mitchell, and Burke
{J. Ajner. Chem. Soc, 1904, 26, 1389, 1413), and by Young and
Burke (ibid., 1906, 28, 315). These authors have shown the
existence of twelve different solid hydrates, besides the anhydride,
have determined their compositions, solubilities, transition points,
and the conditions under which they are formed. They seem to

Fig. 2.

3

^v

Tewptr\tm

1

30'

4

0' 5

<r

e

tf 7

f

8

o'

90

have worked almost entirely with the fused pentahydrate; in a
few cases certain hydrates are said to crystallise from solutions of
different concentrations, but further particulars are not given.
Moreover, their crystallisations were produced from solutions kept
at rest, and the effect of mechanical friction does not appear to
have been tried. ♦

In the present investigation, solutions of widely different con-
centrations have been used; they have been cooled slowly with
constant shaking as in previous work, and mechanical friction has
been brought into play by introducing angular fragments of Jena
glass before sealing. The supersolubility curves for ice and the
secondary monohydrate (Young and Burke's nomenclature is used)
have been traced, both these solid phases giving well-defined
metastable regions. The more concentrated solutions were prepared
by sealing up weighed quantities of the anhydride, the stable form
above 70°, and distilled water in glass tubes; the dilute solutions
were made up from pure recrystallised primary (ordinary) penta-
hydrate. To remove all traces of crystalline nuclei from the more

OF SODIUM CARBONATE AMD SODIUM THIOSULPHATE. 1670

concentrated solutions, it was necessary to heat the tubes for some
time — generally about an hour^ — -in an oil balli to a temperature of
about 180°. The less concentrated tubes were heated in boiling
water.

Crystallisation of Ice. — On cooling solutions of sodium thio-
sulphate of concentrations from zero to about 40 parts per 100 of
water with constant shaking, ice separates out at a definite tem-
perature for each concentration. Table V gives the highest tem-
peratures of spontaneous crystallisation of ice from solutions of
varying strengths.

Table V.

(The tube contained 2'4 to 5"2 grams of solution.)

Parts of Na.,S.,03 in

100 parts" HoO... O-Q 4-01 7-13 14-94 '26-44 28-75 2896 35-31
Tt'iiip. of crvstal-

lisation of ice ... -0-7° -1-9° -2-6° -4-3° -6-9° -7-2" -7-6° -9-2''

The formation of the ice crystals was a very definite phenomenon.
Successive determinations with the same tube generally agreed
within one or two tenths of a degree. The data are plotted on the
diagram inset in Fig. 3, the scale for the ice-curves being double
that of the rest of the diagram. The temperatures of spontaneous
crystallisation are seen to lie on a regular supersolubility curve
running nearly parallel to the freezing-point curve at a distance
from it of from three-quarters to one-half a degree, and gradually
approaching it with increasing concentration. The curve was not
carried further, owing to the inconvenience of working with lower
temperatures; the average temperature of the laboratory was about
30°, rising at times above 40°. Moreover, there were indications
that with increasing concentration the sokitions tended to become
sluggish, and not to crystallise at all within a reasonable time.
A solution of concentration 47-67 did not crystallise at —13°,
although expected to give ice at —11°, and solutions of concen-
trations 79"98 and 80"67 did not crystallise at —15°.

Crystallisation of Na2S203,HoO (^secondary). — When solutions of
sodium thiosulphate of concentrations between 178 and 255 were
slowly cooled and shaken in sealed tubes containing glass fragments,
this solid phase invariably crystallised out. At a definite tem-
perature for each tube, a shower of crystals appeared, causing a
milky appearance in the tube. The crystals were identified as
those of the secondary monohydrate by determinations of their
solubility. In the case of the more concentrated solvxtions, which
crystallised spontaneously between 30° and 55°, the phenomenon
was very definite. Crystallisation always took place after being
kept at a certain maximum temperature with constant shaking for

IfiSO JONES: Sl'ONTAXEOUS CRYSTALLISATION OF SOLUTIONS

ten minutes or a quarter of an hour. Successive determinations
with the same tube agreed to within half a degree. In tlie more
dilute solutions, which crystallised at lower temperatures, 5° to
30°, the crystallisation was somewhat less definite, a rather longer
time being necessary to insure crystallisation. Crystallisation
would, however, always occur after standing half an hour to an
hour at the maximum temperature. The greater length of time
required was due to the greatly increased viscosity of the solutions
at these temperatures. At still lower temperatures, the viscosity

Fir.. 3.

® Crystallisation of ice.

O „ „ Na2S.A.H,0.

became too great to allow of crystallisation taking place within a
reasonable time. The solutions, indeed, became so viscid that they
could neither be shaken nor poured. Such solutions were therefore
unsuitable for determining a supersolubility curve. They would
in general only crystallise aft«r standing for protracted periods,
amounting often to weeks or months. In such cases, it was not
the monohydrate which separated out, but one of the other possible
solid phases, generally the dihydrate or secondary pentahydrate.
Between the concentrations 178 and 255, however, it was always
the monohydrate which appeared on slow cooling, so long as the

OF SODIUM CARHONATE AND SODIUM THIOSULPHATE. 1 081

tube was constantly shaken. Table VI gives the highest tem-
peratures at which spontaneous crystallisation was observed in such
tubes.

Table VI.

(The tube contained from 2'2 to 84 grams of solution.)

Parts of Na^SoOs in 100 parts H2O :

178-99 190-43 191-60 201-13 205-88 222-73 234-62 253-00 255-23
Temp, of crystallisation of NajSoOa.HjO :

9-0° 18-9° 21-9° 28-0° 31-7° 39-2° 45-3° 52-9° 537°

The results are plotted in Fig. 3, and give rise to a regular
supersolubility curve running roughly parallel to the solubility
curve at a distance of about 20° from it. For the sake of clearness
in the figure, only the solubility curves of the more important
hydrates have been shown.

If the tubes were not shaken constantly during cooling, it was
not always the monohydrate which crystallised. In the tube of
concentration 234-6, on one occasion, crystals of the anhydride
were formed when the tube was allowed to cool slowly without
shaking from 50°. This was the only occasion on which the
anhydride was produced spontaneously. It is possible that nuclei
of the anhydride may have been left in the tube, although its
previous treatment renders this unlikely. The dihydrate crystal-
lised out in the tubes of concentrations 191 '6 and 201 "1 when they
were kept at rest at the ordinary temperature, and was identified
by its solubility.

Owing to the viscosity of the solutions, and the long times
necessary for crystallisation for concentrations between about 50
and 170, no systematic investigation of the spontaneous crystal-
lisation of such solutions was made.

Tubes containing 47-67, 79-99, 80-67, 146-39, and 153-38 parts
of NaoSoOg respectively to 100 parts of water did not crystallise after
keeping for some months at the ordinary temperature or after a
short time at about — 10° to — 15°,

Tubes containing 124-09, 145-31, 162-58, 16683, and 16994 parts
of NaoSoOa to 100 parts of water gave secondary pentahydrate on
exposure to temperatures of about —8° to — 15° after standing some
hours.

The spontaneous formation of the primary (ordinary) penta-
hydrate was observed in two tubes only. These had concentrations
of 100-7 and lOri, and were the first two tubes prepared. Since
they had shown themselves to be unsuited for the determination
of a supersolubility curve, they had been set aside and maintained
at the laboratory temperature without being kept under close

VOL. XCV. 5 S

1682 JONES: SPONTANEOUS CRYSTALLISATION OF SOLUTIONS.

observation. On examination five months after, both tubes were
found to contain large, transparent, glassy crystals. Determination
of their solubility showed them to be the ordinary pentahydrate.
This was confirmed by the fact that on warming there was no
sign of any change into a different hydrate, as would probably have
occurred with any other hydrate heated to the same temperature,
39° to 40°. Moreover, after having dissolved the crystals until
only a small fragment remained, and then allowing to cool slowly
with shaking, a shower of brilliant little monoclinic prisms was
obtained identical in appearance with the ordinary pentahydrate.
According to Young and Burke, the spontaneous production of
this solid phase was never observed in solutions or fusions of
sodium thiosulphate. They found, however, that it was produced
from all the other solid hydrates by exposure to a temperature of
— 35°. It is noteworthy that in the only two cases in which the
spontaneous formation of this phase has been observed, the con-
centrations were nearly the same — 100 "7 and 101 '1 — and it would
seem, therefore, that at such concentrations the dissolved salt was
in the most favourable condition to form this hydrate. It is certain
that in the tubes under discussion no solid nuclei of the penta-
hydrate w^ere present. For in spite of having been cooled to low
temperatures, no crystallisation of this hydrate was observed during
the space of a week ; and it is probable that no crystallisation took
place before some months of standing.

Summary.

1. Supersaturated solutions of sodium carbonate, freed from
crystal nuclei, crystallise at definite temperatures on being subjected
to mechanical friction.

2. Supersolubility curves have been traced showing the conditions
under which ice, Na2CO3,10H2O, and NagCOgjHgO are formed
spontaneously from sodium carbonate solutions.

3. Contrary to Ostwald's law of successive reactions, the less
stable NaQCOgjTHgO is only rarely produced spontaneously. The
conditions favouring the spontaneous formation of this phase appear
to exist only in solutions of concentrations between certain narrow
limits. In such solutions, however, the tendency to produce the
decahydrate appears to be equally well marked.

4. Supersaturated solutions of sodium thiosulphate, freed from
crystal nuclei and between certain limits of concentration (0 to 40
and 179 to 255 parts of anhydrous salt to 100 parts of water),
crystallise at definite temperatures when subjected to mechanical
friction.

5. Supersolubility curves have been traced showing the conditions

BOYLE : THE lODOBENZENEMONOSULPHONiC ACIDS. PART I. 168?}

under which ice and Na2S203,H20 (secondary) crystallise spon-
taneously from solutions of sodium thiosulphate.

6. Under the conditions employed — slow cooling and constant
shaking — ice and NaoS^OgjHoO are the only two of the fourteen
possible solid phases which crystallise out spontaneously within
the space of one or two hours.

7. The spontaneous production of anhydrous Na^S203, primary
NaoS203,2II.20, secondary Na2S203,5H20, and ordinary (primary)
Na2S203,5H20 has been observed in solutions of sodium thiosulphate
kept at rest for longer periods. Owing to the viscosity of tho
solutions, and the long time necessary for crystallisation, it was not
found practicable to trace any regular relationship between the
temperature of crystallisation and the concentration of the solution.

Government College,
L\HOUE, India.

CLXXXVI. — The lodohenzencTnoYLOsal'phonic
Acids. Part 1.

By Mary Boyle.

Although a large number of chloro- and bromo-derivatives of
benzenesulphonic acid and of the homologous acids have been
prepared, little is known of the corresponding iodo-compounds, the
0-, m-, and jj-iodo-derivatives alone being known in the case of
benzenesulphonic acid.

The investigation, of which the first part is described in this
communication, has for its object the preparation and study of the
higher iodo-derivatives of benzenesulphonic acid, and an account
is given of 2 : 4-, 2 : 5-, 3 : 4-, and 3 : 5-di-iodo-, and 2 : 3:5-,
2 : 4 : 5-, and 3:4: 5-tri-iodo-benzenesulphonic acids.

Historical.

p-Iodobenzenesulphonic acid was first described in 1872 by
Korner and Paterno {Gazzetta, 2, 448), who prepared it from
iodobenzene and fuming sulphuric acid; it was subsequently pre-
pared by Lenz in 1877 (Ber., 10, 1135) by displacing the amino-
group of aniline-2;-sulphonic acid by iodine.

The ortho-acid was prepared hy Bahlmann in 1877 {Annalen,
186, 325) by the action of fuming hydriodic acid on the diazo-salt
of aniliue-o-sulphonic acid ; the meta-acid was prepared in like
manner from aniline-m-sulphonic acid by Langmuir in 1895 {Ber.,
28, 93). Iodo-derivatives of several sulphonic acids of the

5 S 2

1684 BOYLE : TflE 10DOBEN2ENEMONOSULPHONIC ACIDS. PART 1.

liomologues of benzene have also been prepared, namely, o-iodo-
toluenesulphonic acid by Mabery and Palmer {Amer. Chein. J.,
1884, 6, 170); the para-derivative by Glassner {Ber., 1875, 8, 560)
and de Roode {Amer. Chem. J., 1891, 13, 233); a disulphonic acid
of j;-iodotoluene by Richter {Annalen, 1885, 230, 325); an
iodoxylencsulphonic acid by Hammerich {Ber., 1890, 23, 1635); a
di-iodoxylenesulphonic and an iodomesitylcnesulphonic acid by Tohl
(Tohl and Bauch, Ber., 1893, 26, 1107; Tdhl and Eckel, Ber., 1893,
26, 1101), besides others of a more complex nature.

Theoretical.

The sulphonation of iodo-compounds in all cases involves the
formation of compounds richer in iodine, the sulphuric acid acting
to a certain extent as a carrier of halogen, and causing the transfer
of iodine from one molecule to another. Such sulphonating experi-
ments, therefore, result in the production of at least three sub-
stances, namely, (1) a compound containing more iodine in the
nucleus than the original substance; (2) an iodosulphonic acid; (3)
a sulphonic acid free from iodine, the molecule which has lost
the iodine being, as a rule, readily attacked by the sulphonating
agent. Such was observed to be the case by Hammerich {loc. cit.),
who subjected iodo-??i-xylene to the action of concentrated sulphuric
acid, also by Neumann (Aimalen, 1887, 241, 47) during his
investigation of the action of sulphuric acid on iodobenzene.

The latter observer studied the conditions under which
sulphonation of the iodo-compound is possible, and arrived at the
conclusion that strength of acid, proportions of the interacting
substances, and temperature are all important factors to be taken
into consideration. As a rule, concentrated acid favours sul-
phonation, high temperatures the production of di-iodobenzene.

My first attempts to prepare 2 : 5-di-iodobenzenesulphonic acid
were made on the lines of these experiments, since it was evident
that if p'io<io*'iili'^6 or ^^-iodoacetanilide could be directly sul-
phonated, the conversion of either product into the required acid
would be a matter of little difficulty. The results were very
uDsatLsfactory.

In the case of iodoaniline hydrochloride, no sulphonation was
effected at low temperatures, and, on gently heating the mixture,
iodine was copiously evolved; in the case of iodoacetanilide, when
the conditions were such as to render sulphonation possible, a
considerable amount of iodine was evolved, and the sulphonic acid
obtained did not contain the halogen.

It may be noted that similar results have been obtained with

BOYLE : THE lODORENZENEMONOSULPHONIC ACIDS. PARTI. 1085

ioclophcnolic compounds by Neumann {lor. rif.), his attempts to
prepare an iodophenolsulpbonic acid by direct sulplionation of the
iodophenol having resulted, at the ordinary temperature, in the
elimination of iodine, and, at low temperatures, in the formation
of a di-iodo-derivative unaccompanied by any sulphonic acid.

The action of sulphonating agents on 2>di-iodobenzene was next
studied, but with not much more satisfactory results.

The di-iodobenzene was treated both with the calculated amount
and with excess of concentrated sulphui'ic acid, with fuming acid
of various strengths, and with sulphur trioxide at many different
temperatures. At the ordinary temperature, no action took place
with either concentrated or fuming acid; at the temperature of
the water-bath, fuming acid caused the formation of tri- and tetra-
iodobenzene and a trace of a sulphonic acid. The vapour of sulphur
trioxide, when passed over dry and slightly warm di-iodobenzene,
caused the formation of small quantities of the higher iodo-
derivatives of benzene, but when the experiment was carried out
at higher temperatures, the proportion of unchanged material
became much less, and a small amount of a crystalline di-iodo-
Ijenzenesulphonic acid was isolated.

The j'ield, however, was so extremely poor, being, under the
most favourable conditions, less than 10 per cent., and becoming
much less when large quantities were dealt with, that the method,
as a means of preparing a large amount of the acid, was seen to be
hopeless, and was abandoned.

The possibility of introducing iodine into substances already
containing a sulphonic group was next considered. A patent by
Kalle and Co. (D.R.-P. 129808), describing the preparation of iodo-
substituted derivatives of aniline-w- and -p-sulphonic acids, indicated
that success in that direction had already been achieved. A brief
description of the preparation of the iodo-derivatives of these acids
is given in the patent, bi;t, as far as can be gathered from a study
of subsequent literature, they have not been investigated with a
view to the determination of their structure ; and others, prepared
by myself, which form the starting point for the preparation of
several iodobenzenesulphonic acids described in this paper, are not
mentioned.

Of these sulphonic acids, 3 : 4-di-iodobenzenesulphonic acid,
prepared from the monoiodoaniline-77-sulphonic acid described by
Kalle and Co., which is readily obtained in large amount, was first
studied ; the preparation of 2 : 5-di-iodobenzenesulphonic acid, which
involves the production of aniline-o-sulphonic acid, and is a more
lengthy operation, was undertaken later.

1686 BOYLE: THE lODORENZENEMONOSULPHONIC ACIDS. PARTI.

Of the six theoretically possible di-iodobenzenesulphonic acids,
the following four:

SO3H SO3H SO3H SO3H

I 1

and, of the six theoretically possible tri-iodobenzenesulphonic acids,
the following three:

SO3H SO3H SO3H

I I

have been prepared and examined by the author.

Only two of these acids, namely, 2 : 5- and 3 : 4-di-iodobenzene-
sulphonic acids, have been thoroughly investigated with regard to
the properties of the acids, their derivatives and salts; derivatives
and salts of the other acids have been prepared, but have not as
yet been studied.

Indirectly, during the course of the work, several iodoaniline-
sulphonic acids, isomeric with that described by Kalle and Co.,
and some iodonitrobenzenesulphonic acids in the form of their
potassium salts, have been prepared but not subjected to
examination.

It is stated in the specification of the patent referred to that
mono- and di-iodoaniline-p-sulphonic acids are produced from aniline-
jj-sulphonic acid by the action of one and two molecular proportions
of iodine monochloride respectively, and that a di-iodoaniline-
77i-sulphonic acid is formed under very similar conditions. On
carrying out experiments with aniline-??2-sulphonic acid under the
conditions described by Kalle and Co., the statement that a di-iodo-
acid is produced was confirmed, but it was found that under
carefully regulated conditions a monoiodoaniline-m-sulphonic acid
may also be prepared, and, as the constitution of this acid is readily
determined, its formation is of service in the elucidation of the
constitution of the more highly iodinated product. Judging from
the results obtained with aniline-m- and -jJ-sulphonic acids, it was
to be expected that aniline-o-sulphonic acid should also give rise
to iodo-substituted derivatives; experiments in this direction have
been attended with marked success, well-defined crystalline mono-
iodo- and di-iodo-aniline-o-sulphonic acids having been obtained.

The constitutions of these six iodoanilinesulphonic acids are, in
most cases, quite clear, and rigid proofs of structure have been
obtained in the case of four of them.

Monoiodoaniline-ip-sulphonic Acid. — In the case of monoiodo-

BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI. U)87

aniline-p-siilphonic acid, the formation of ///-iodobenzenesulphonic
acid (identified in the form of its amide) on the removal of the
amino-group by the diazo-metliod, is proof that the iodine atom
occupies the ortho-position with respect to the araino-group ; con-
sequently, the di-iodo-acid, obtained by directly displacing the
amino-group by iodine, is 3 : 4-di-iodobenzenesulphonic acid.

Monoiodoaniline-vQ.-sul'phonic Acid. — As this acid is convertible
into a di-iodosulphonic acid identical with that obtained from
monoiodoaniline-^sulphonic acid, the ortho-position with respect to
the amino- and the para-position with respect to the sulphonic
group must be occupied by iodine, as 6-iodoaniline-?«-sulphonic acid
is alone capable of giving rise to 3 : 4-di-iodobenzenesulphonic acid.
Recent work by Brenans (CompL rend., 1904, 138, 1503; 139, 63)
and by Korner and Contardi (A Hi R. Accad. Lincei., 1908, [v],
17, i, 465) on the iodination and bromination of 77z-nitroaniline is
of interest in connexion with the iodination of aniline-m-sulphonic
acid, inasmuch as it admits of a comparison being made between
the influences exerted by the negative nitro- and sulphonic groups
on the position assumed by the entering halogen atom. Brenans
states that the action of iodine chloride on w-nitroaniline dissolved
in acetic acid results in the production of 6-iodo-3-nitroaniline,
2 : 4-di-iodo-3-nitroaniline, and 2 : 6-di-iodo-3-nitroaniline.

That is to say, the first atom of iodine assumes the same position
relatively to the amino- and nitro-groups as it does in aniline-
m-sulphonic acid with respect to the amino- and sulphonic groups,
thus:

I I

\.

\nH„ and ( >NH

<:>

2 »

NO2 SO3H

but the second atom of iodine seems (according to Brenans) to be
as readily introduced into the second ortho-position as it is into
that para- with respect to the amino-group ; I find, however, in the
case of aniline-7?2-sulphonic acid, that the second atom of iodine, as
will be shown later, enters only into the para-position.

The results of Korner and Contardi's observations on the
bromination of m-nitroaniline dissolved in acetic acid are not in
harmony with the above, bromine entering into the para-position
by preference, and only to a small extent into the ortho-position
with respect to the amino-group, which is that assumed in the first
instance by iodine, thus :

^r

Br/^ "^NHg and <^ ^NHg .

1688 BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PART I.

It is further stated that, if the para-position is occupied, the
bromine atom enters either ortho-position indifferently, thus :

Br

NHg and R(( >NH2

NOo Br

In the case of aniline-7??-sulphonic acid, only one di-iodo-
derivative has been isolated, and it has not yet been found possible
to displace the hydrogen in the position between the amino- and
sulphonic groups by the halogen, so that there is an essential
difference between the nitro- and sulphonic groups as regards their
directive influence, the latter in conjunction with the amino-group
forming, as it were, a screen which prevents all interaction with
the enclosed hydrogen atom. The impregnability of this second
ortho-position was clearly manifested in an experiment with j^-nitro-
aniline-m-sulphonic acid, a solution of which, in very dilute hydro-
chloric acid, was treated with a considerable excess of iodine
chloride. It was thought that, as the para-position was occupied,
the second atom of iodine would enter the second ortho-position,
but under no conditions could a di-iodo-derivative of any kind be
obtained, the monoiodo-compound of the following constitution
being alone produced :

I

The failure to introduce iodine into this position and the non-
formation of a tri-iodoaniline-//i-sulphonic acid is the more remark-
able in that a tribromoaniline-?M-sulphonic acid has been obtained
by Berndsen {Annalen, 1874, 174, 84) and by Reinke (Annalen,
1877, 186, 286) by the action of bromine on aniline-m-sulphonic
acid. This failure may be due to the very sparing solubility of the
di-iodo-acid, which is rapidly removed from the further action of
the iodine chloride, but such a suggestion will not serve to explain
the results obtained with 2>nitroaniline-7;i-sulphonic acid which
remained in solution throughout.

Monoiodoaniline-o-sulphonic Acid. — The action of iodine chloride
on a solution of aniline-o-sulphonic acid gives an excellent yield of
the monoiodo-derivative. Further action under specially regulated
conditions which are discussed in the experimental part of this
paper, gives rise to a di-iodo-derivative; under no conditions, as
was to be expected, can a third iodine atom be introduced into
the nucleus.

Tlie monoiodoaniline-o-sulphonic acid is the pure para-compound,

BOYLE : TFIE lODOBENZEXEMONOSULPHOXIC ACIDS. PARTI. 1689

free from any admixtiire of the ortho-isomoride ; if produced at all,
the latter must be present in such small amount as to escape
detection; the second iodine atom enters the free ortho-position.
That the iodine atoms occupy the positions stated has been clearly
demonstrated. As it was clear that the iodine atom in the mono-
iodo-derivative was in either the para- or the ortho-position with
respect to the amino-group, the displacement of the latter by
hydrogen, leading, as it would, to 7w-iodobenzenesulphonic acid
in both cases, could give no definite information as to the con-
stitution of the acid. The amino-group was therefore displaced by
iodine, and attempts were made to remove the sulphonic group and
obtain a di-iodobenzene. These attempts, as might be expected,
proved unsuccessful. The acid proved to be perfectly stable when
heated in superheated steam ; and when a mixture of the potassium
salt with sulphuric acid was heated in the same way, although
the sulphonic group was removed, the product became further
iodinated in the presence of the sulphuric acid; tri- and tetra-
iodobenzenes were isolated, but no trace of a di-iodobenzene could
be detected.

Finally, the relative positions of the amino-group and the iodine
atom in monoiodoaniline-o-sulphonic acid were demonstrated by the
preparation of the latter from p-nitroaniline-Tn-sulphonic acid :

"^2

.-r ^ --^\_/^

SO3H SO3H SOgH

l_

SO3H

The constitution of the di-iodobenzenesulphonic acid prepared
directly from this acid is therefore definitely settled :

"SOgH

Di-iodoaniline-0- and --p-sulphonic A cids. — Although the monoiodo-
derivatives of aniline-o- and -j^-sulphonic acids may theoretically each
give rise to three isomeric di-iodo-derivatives, taking into account
the well-known fact that halogens always act on amino-compounds
in such a manner that the halogen enters into either the ortho- or
the para-position, the only two derivatives to be considered are the
following :

I I

1 690 BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PART I.

On displacement of the amino-group by hydrogen, these two acids
should yield one and the same di-iodosulphonic acid ; this was
foixnd actually to be the case :

I _I I

~SO,H "sOgH ~I

The two tri-iodo-acids prepared directly from these amino-acids
must be therefore 2:3: 5-tri-iodobenzenesulphonic acid and 3 : 4 : 5-
tri-iodobenzenesulphonic acid respectively :

SO3H SO,H SO3H SO3H

'I Ir -^ i\ \i and jl Ij -^ jl Ij .

NHg I

It was thought that independent confirmation of the position of
the iodine atoms in the two di-iodoamino-acids would be afforded if
the series of changes could be effected which is indicated in the
two following schemes, the first having in view the determination
of the position assumed by the first iodine atom :

NH, NH2 III

-^<^2__^Ir lN02_. If >N02 If \NH2

S03H S03H S03H S03H S03H

the relative positions of the iodine atoms in the last acid being
known ; and the second, the proof of the constitution of 2 : 6-di-iodo-
aniline-p-sulphonic acid :

NH2 NH2 I I

Jl. , ^-^ >■ ^ — ^ ^

SO3H SO3H SO3H SO3H ^ i/\i

NHo NH2

1/ \I /^ SO3H

SO3H SO3H

If the tri-iodo-acid finally obtained, the constitution of which
is definitely settled by the method of its production, is identical
with the one obtained from di-iodoaniline-p-sulphonic acid, the
constitution of the latter is also clear. An unexpected difficulty,
however, arose in attempting to carry out the experiment. The
nitroaniline-7J-sulphonic acid readily absorbed iodine under the usual
conditions, but when this iodo-derivative was diazotised and treated

BOYLE : THE lODOREXZENEMONOSULPHONIC ACIDS. PARTI. 1601

with potassium iodide, a crystalline potassium salt was detained,
which proved to be a salt, not of the expected di-iodonitrosulphouic
acid, but of the tri-iodobenzenesulphonic acid of the second scheme,
the nitro-group having been displaced by an iodine atom.

A similar displacement of a nitro-group by iodine was not
observed in the case of the isomeric 4-nitroanilinc-7/7-sulphonic acid,
which exhibited normal behaviour throughout, so that it seems
that the proximity to the nitro-group of the amino-group which is
subjected to the action of nitrous acid, is an important factor in
determining the nature of the interaction.

As regards the problem under consideration, although, owing
to the abnormal character of the change, the result scarcely affords
decisive proof, the formation of the tri-iodosulphonic acid from a
monoiodo-derivative, in which the iodine is undoubtedly in the
ortho-position with respect to the amino-, and in the meta-position
with respect to each of two negative groups, is convincing evidence
of the constitution of the acid.

Di-wdoa7iiIh}e-m-si/Ijj/ionic Acid. — That this acid is the 4: 6-di-
iodo-acid, and that the tri-iodo-acid formed from it is the
2:4: 5-tri-iodo-acid, is quite clear from the following considerations.

1. The removal of the amino-group from di-iodoaniline-
w-sulphonic acid involves the production of a di-iodobenzene-
sulphonic acid which, from other modes of preparation, must be
regarded as 2 : 4-di-iodobenzenesulphonic acid. Two possible con-
figurations of the amino-acid could give rise to this substance,
namely:

NHg NH„

— > 1/ \I ^- I

SO,H I JS0,H L JS0,H

\/ ^ \/

'3'

This di-iodo-acid can be prepared from 5-nitroaniline-o-sulphonic
acid in such a way as to establish its constitution by the following
series of changes :

NO/ >NH, __^ NO21 ,. _^

NH / \I

SO,H ~^ I JSO3H

One iodine atom in di-iodoaniline-7??-sulphonic acid therefore
occupies the para-, the second the ortho-position, with respect to the
sulphonic group.

2. If 4-nitroaniline-772-suIphonic acid is treated with iodine
chloride, it yields a monoiodo-derivative, from which a tri-iodo-acid

1692 BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI.

may be obtained by carrying out the changes expressed in the
following scheme :
NHo

SO,H

N0„

NH2

I

NO2

-^

I^^S03H
NO2

I

I

l/\

l/\

NH,

I

— >

In this manner, the same tri-iodosulphonic acid is obtained as
may be produced directly from di-iodoaniline-»2-sulphonic acid.
The constitution of the original nitroamino-acid requires that the
tri-iodo-acid finally obtained shall possess two iodine atoms in para-
positions with respect to each other.

Since, therefore, one iodine atom must be in the para-position
with respect to the sulphonic group and two others in para-positions
with respect to each other, the constitution of the tri-iodo-acid is
settled beyond question as being 2:4: 5-tri-iodobenzenesulphonic
acid.

The following table shows at a glance how the seven acids under
discussion may be obtained from the anilinesulphonic acids :

NH2 NH,
SO3H

NH2

/ \ / \

/ \

NH2 NH. NHj
SO.H SO3H I

NHo

l^'^SOaH

I

NH2 NH,
I

1 / \ / \

1

/ \

I I I

/\l Ij^^I I^I Ij^'^S03H

\/ \y \/ \y

SO.,H SO.,H SO.H I

I

I

I
I I

The iodobenzenesulphonic acids are all extremely sohible in water,
much less so in mineral acids ; they all crystallise well from mineral
acid solutions ; the 2 : 5-di-iodo- and the ^2:4: 5-tri-iodo-benzene-
sulphonic acids crystallise extremely well from water alone.

The chlorides crystallise in well-defined forms; the amides are
white powders insoluble even in hot water, but, in the case of the
tri-iodo-compounds, crystallise well from alcohol; the two anilides

BOVLE: the IODOBENZENEMONOSULFHONIC acids. I'AUT I. 1693

which have been prepared can also be crystallised from alcohol.
The acids are characterised by forming beautifully crystalline salts
and esters.

The diazo-anhydrides of the iodoaminosulphonic acids considered
in this paper are all coloured, the colour varying from the palest
yellow, almost cream colour, in the case of 2;-iodoaniline-o-sulphonic
acid, to bright yellow in the case of all the di-iodoamino-acids. They
are only sparingly soluble in sulphuric acid, and are comparatively
stable in the dry state.

Melting Points of the Acids and of their Derivatives.

Benzene- Anhydrous Ethyl

sulphonic acids. acid. Chloride. Amide. ester. Aiiilide.

3:4-Di-iodo 122—125° 82° 227° 81° —

2:5-Di-iodo 132° 131—132° 211—230° 112-5° —

3:5-Di-iodo 146 92-5 210—218 — —

2:4-Di-iodo 167 78 230 — —

3 : 4:5-Tri-iodo .. 211 145 above 250 — 201°

2:4:5-Tri-iodo .. 230 135 ,, 288 155 194—196

2:3:5-Tri-iodo .. 210—215 122-5 ,, 280 110 —

Experimental.
3: 4:-Di-iodobenzenesulphonic Acid.

The material used for preparing this acid is the monoiodoaniline-
y>sulphonic acid described by Kalle and Co. (lac. cit.). IT-^" Grams
of aniline-^-sulphonic acid are dissolved in about 2 litres of hot
water, the solution cooled and mixed with 30 c.c. of concentrated
hydrochloric acid; after cooling the mixture to about 10°, a
molecular proportion of iodine chloride (16-3 grams) is drawn into it,
the flask containing the chloride being heated on a water-bath
kept at 70 — 80°, and the exit tube from the flask containing the
acid solution being attached to the pumj).

The dark brown mixture was kept for twelve hours, and
then evaporated to crystallisation; the long, white needles which
separated were purified by crystallisation from water. The yield
of monoiodoauiliue-2;-sulphonic acid approximated to 50 per cent,
of the theoretical :

Found, C = 23-84; H = l-92; N = 4-71; 1 = 42-54.

CoH,03NIS requires C = 24-08; H = 2-00; N = 4-68;
I = 42"47 per cent.

Constitution of Monoiodoaniline-p-stdphomc Acid. — Although
there could be little doubt that the iodine occvipied the position
ortho- with respect to the amino-, and meta- with respect to the
aulphonic group, in order completely to verify the point, the amino-

1694 BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PART I.

group was displaced by hydrogen and the resulting ?/z^iodobenzene-
sulphonic acid was converted into its amide and identified.

The displacement of the amino-group by hydrogen was effected
by boiling the diazo-anhydride (Found, N = 9'14. CcHgOsNgIS
requires N = 9"03 per cent.) with methylated spirit or with 95 per
cent- alcohol under a pressure slightly above the ordinary. Under
the atmospheric pressure, using absolute alcohol, the amino-group
was also partly displaced by the ethoxy-group. The flask containing
the mixture was attached to a reflux condenser, and a tube bent
twice at right angles was inserted through the tightly-fitting cork
closing the top of the condenser; the whole length of the further
limb of this tube, about 400 mm. long, was immersed in mercury
(compare Schmitt, Aniialen, 1861, 120, 152; Ador and Meyer,
ibid., 1871, 159, 10). After some time, a vigorous evolution of
gas occurred and the diazo-compound passed into solution, a deep
red colour being developed. On evaporating the liquid on the
water-bath, a dark red, pasty mass remained; on diluting this
slightly, and pouring it into a saturated solution of common salt,
a copious, brownish-yellow precipitate of sodium iodobenzene-
Tn-snhphonate was obtained. This salt was shaken with animal
charcoal, and a portion further purified and freed from all traces
of chloride by dissolving it in absolute alcohol :

Found, C = 23-93; 1 = 41-31.

C6H403lSNa requires 0 = 2353; 1 = 41-50 per cent.

The purified salt was then treated with the requisite amount of
phosphorus pentachloride, the liquid mixture heated for some time
on the water-bath, and then added to concentrated ammonia. On
gently warming, a voluminous, white precipitate was obtained,
which, after crystallisation from water, separated in needles melting
at 150 — 151°. The recorded melting jioint of iodobenzene-
??i-sulphonamide is 151 — 152°. The original amino-acid was thus
jDroved to be o-iodoaniline-p-sulphonic acid.

To jorepare 3 : 4-di-iodobenzenesulphonic acid, a solution of 20
grams of o-iodoaniline-j>sulphonic acid was rendered faintly
alkaline with sodium carbonate, and mixed with 4-7 grams of
sodium nitrite ; the mixture was then poured gradually into 300 c.c.
of dilute sulphuric acid cooled to 2°.

After about three hours, 15 grams of potassium iodide were
added, and the mixture heated on the water-bath until all the
nitrogen was evolved, and a clear I'ed solution was obtained. Prac-
tically no evolution of gas took place below 15°; at that point
vigorous effervescence began, the diazo-compound passing rapidly
into solution.

In many experiments, when crude iodoaniliue-j^-sulphouic acid

BOYLE : THE lODOBENZENEMONOSULPHOXIC ACIDS. PARTI. 1695

was employed, and a slight excess of iodine chloride had been used
in its preparation, fine, sparkling crystals made their appearance
at this stage even in the hot solution ; these, on examination, proved
to be potassium 3:4: 5-tri-iodobcnzenesulphonate, a salt which is
almost insoluble in water and is readily formed from di-iodo-
aniline-j^sulphonic acid by displacement of the amino-group by
iodine.

This acid and its derivatives are described on p. 1711.

When pure recrystallised iodoanilinc-jj-sulphonic acid was used,
no crystals separated until the red solution had been considerably
concentrated ; on cooling, a mass of glistening, pale yellow crystals
separated, which became colourless on recrystallisation, crystallising
from water in small needles and from alcohol in shining scales.
Concentration of the mother liquor yielded a further crop of the
same crystals, which proved to be 'potassium 3: A-di-iodobenzene-
sulphonate. The yield of potassium salt was in some cases 70
per cent, of the theoretical :

Anhydrous salt : Found, 1 = 56-39; K = 8-58.

CcHgOgloSK requires I = 56"69; K = 8'70 per cent.

Hydrated salt: Found, C = 15-55; H = l-01.

CcIIsOsIoSK^HaO requires C = 15-45; H = r07 jjer cent.

3 : 4-Di-iodobenzenesulphonic acid was prepared from the
potassium salt by converting the latter into the barium salt, and
decomjDOsing this with excess of dilute sulphuric acid; the acid
solution was evaporated on the water-bath until, on cooling, masses
of shining flakes separated. These were collected, dissolved in a
little water, and precipitated with concentrated hydrochloric acid.
The white crystals obtained were washed free from sulphuric acid
with concentrated hydrochloric acid, dried on a porous plate, and
freed from hydrochloric acid in a desiccator containing potassium
hydroxide.

3 : A-Di-iodob enzenestdphonic acid is a white, crystalline substance,
extremely soluble in water, but is precipitated from the aqueous
solution by acids. It does not crystallise well from water, attempts
to purify it in this way giving a paste which filters extremely slowly,
and, when pressed on a porous plate and left in the desiccator, dries
to a hard cake. The dry acid is soluble in ether, and, when
recovered from ether or when precipitated from a solution by
hydrochloric acid, is extremely deliquescent. The crystals obtained
from water, when dried in the air on a porous plate, melt irregularly
from 80° onwards; when dried at 100° they melt at 122—125°; if
the dried acid is once more exposed to moist air for a short time,
the melting point is rapidly lowered to 80°.

There ia no doubt, therefore, that the acid contains water of

1696 BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI.

crystallisation ; the actual number of molecules has not yet been
determined, owing to the difficulty of obtaining it in a sufficiently
defined crystalline form.

Analysis of a specimen dried on porous plate in the desiccator
seems to point to one molecule of water of crystallisation, but as
there is every probability that partial dehydration had occurred,
the point must be left undecided for the present:

Found, C = 16-69; 1 = 58-75.

C6H403l2S,H20 requires C = 16-82; 1 = 59-34 per cent.

Salts of 3: A-Di-iodobenzenesulphonic Acid. — The salts of this
acid crystallise well from water. Many have been prepared, but
of these only the sodium, barium, and lead salts have been
thoroughly investigated with regard to their solubility and water
of crystallisation ; it is proposed to study the others similarly, and
to communicate the results in a later paper.

Sodium 3: 4:-Di-iodobenzenesulphonate. — This salt was prepared
from the pure acid by neutralisation with sodium hydroxide and
recrystallisation from water. It crystallises in beautiful, white,
glistening plates. For the determination of the water of crystal-
lisation, the pure air-dried salt was heated to 160°:

Hydrated salt : Found, Na = 5-05; H20 = 3-95.
C6H303l2SNa,H20 requires Na = 5-il; HoO = 4-00 per cent.

Anhydrous salt : Found, C = 16-82; H = 0-93; 1 = 59-28; Na = 5-18,
CeHaOalgSNa requires 0 = 1666; H = 0-69; 1 = 58-79;
Na = 5-32 per cent.

Solubility. — One hundred grams of water dissolve 3-47 grams of
the anhydrous salt at 22-5°.

Barium 3: 4:-Bi-iodobenzenesulphonate. — The barium salt was
prepared from the pure acid by neutralisation with barium car-
bonate, and also by precipitation from the ammonium salt.

It crystallises in very small, white needles containing one
molecule of water of crystallisation. For the determination of the
water, about 1 gram of material was heated during several hours
at 125°, two hours at 135°, and finally three hours at 140°; heating
at 155° during another hour caused no further decrease in weight,
but, on raising the temperature to 210°, decomposition, accom-
panied by darkening and considerable loss in weight, occurred :

Found, 1 = 52-44; Ba = 13-58; 1100 = 1-68.

CjoH606l4S2Ba,H20 requires" 1 = 52-20; Ba = 13-65;
H20 = r84 per cent.

Solubility. — ^^One hundred grams of water dissolve 027 gram of
the anhydrous salt at 21-5°.

Lead 3: A-Di-iodobenzenesulphonate. — The lead salt separates

bOYLfc: THE lODOBENZENEMONOSULPiiONIC ACIDS. PARTI. 1607

from water in very fine, white needles containing two molecules of
water of crystallisation. The water was determined at two different
temperatures, 170° and 250°, but identical results were obtained
in the two cases :

Found, C = 13-72; 11 = 0-85; ILO = 3-38.
Cj2H,;0,T4SoPb,2il20 riquires C = 13-57; H = 0-94 ; HoO = 3-50 per cent.

A iiiiiio/iii/in Salt. — This salt is extremely soluble in water, and
it was not possible to obtain it in a crystalline condition.

Silver Salt. — This was obtained by precipitation from the
ammonium salt ; it crystallises from water in transparent needles,
and darkens on exposure to light.

The nickel, cobalt, manganese, cerium and copper salts have all
been prepared in small amount by precipitation from a fairly
concentrated solution of the ammonium salt ; they may be described
roughly as follows.

Siclccl salt: beautiful, long, green plates; cobalt salt: long, flat,
pink crystals; iiiainjain'sc salt: small, white, Sparkling crystals;
cer'uun salt: thick, white nodules; cwpper salt: small, blue plates.

3 : 4:-JJi-lo(lubenzenesi(l2)/to/ii/l Chloride. — The chloride was pre-
pared in some cases from the dry potassium salt, in others from
the pure anhydrous acid by the action of phosphorus pentachloride.
The potassium salt (S'S grams) and pliosjDhorus pentachloride (2-8
grams) were mixed, and heated on a water-bath during one hour.
After cooling, water w^as added gradually, and, after one hour, the
chloride was isolated by extraction with ether. Small, transparent
needles, in many cases white nodiiles, separated, which, when
recrystallised from ether, or, better, from a mixture of equal parts
of benzene and light petroleum, separated in very long, transjoarent
needles, melting at 82°, which, however, became white and opaque
when left in the desiccator over sulphuric acid :

Found, C = 1711; H = 0-83.

QHyOoClLS requires C = 16-80; H = 0-74 per cent.

3: A-Di-iodohenzenesuljjlionainide. — The amide was prepared from
the crude chloride by adding it gradually to excess of cooled, con-
centrated ammonia, a white mass being at once precipitated. This
was collected and well washed with cold water. It is insoluble in
cold, and only sparingly soluble in hot, water, but is readily soluble
in alcohol, from which, however, no separation of crystals takes
place. For purification, it was either dissolved in 95 per cent,
dlcohol, and a few drops of water added to the warm solution until
a turbidity was produced, or boiled repeatedly with water. It is
a fine, white powder, which burns with a luminous, smoky flame,
giving off iodine, and evolves alkaline fumes when heated with
sodium hydroxide. Its melting point is 227°:

VOL. XCV. 5 T

1698 BOVLE: TllK lODOBENZENEMONOSULPHONiC ACIDS. PARTI.

Found, C = 17u6; H = l-28; 1 = 6213.
CjjHANIoS requires C = 17-60; H = r22; 1 = 62-10 per cent.

Ethyl 3: A-Di-iodobcnzenesulp7ionate. — This wvas prepared by
warming the sulphonyl chloride with twice its volume of absolute
alcohol in the presence of excess of sodium hydroxide. On cooling,
the mass was extracted with ether, and the ethereal solution, on
evaporation, left white needles, melting at 81°.

2: 5-Di-iodobe?izenesulphonic Acid.

To obtain this acid, aniline-o-sulphonic acid was prepared by
sulphonating j>bromoacetanilide with concentrated sulphuric acid
(Kreis, Annalen, 1895, 286, 377), and then removing the bromine
by means of zinc dust and sodium hydroxide. It may be mentioned,
however, that six hours' boiling with these agents, the time pre-
scribed, w^as in all cases totally insufficient to reduce the bromo-
compound.

As the strongly alkaline liquid was found to attack Jena flasks,
a large open porcelain dish was used and the water renewed at
intervals, boiling being continued during ten to eleven hours.
Excellent yields of the acid in the form of gx'ey, rhombic crystals
were obtained in this way.

Action of Iodine Chloride on Aniline-o-sidijhonic Acid. — The
iodine chloride was passed into the solution of the acid under
conditions very similar to those adopted in the corresponding
experiments with aniline-jJ-sulphonic acid. It is essential to use a
dilute solution of the acid in preparing the pure iodo-compound,

17-3 Grams of aniline-o-sulphonic acid were dissolved in about
1-75 litres of warm water. After cooling, 30 c.c. of concentrated
hydrochloric acid were added, the solution cooled to 10°, and 163
grams of iodine chloride drawn through as in earlier experiments.
From the reddish-violet solution, silky, grey crystals slowly
separated; by the end of the experiment, a semi-solid mass was
obtained.

After several hours, the crystals were collected and well washed
with water. On concentrating the mother liquor, more crystals
were obtained, but accompanied by beautiful, long, violet
needles, which were very heavy, and could be separated to some
extent mechanically from the grey plates ; they consisted of di-iodo-
aniline-o-sulphonic acid, a product which accompanies the mono-
iodo-compound to a very slight extent under every condition so far
tried.

In one experiment, when 4 grams in excess of the theoretical
quantity of iodine chloride had been passed into the solution of the
amino acid, aljout I'j grams of these purple needles were extracted

BOYLE : THE lODOBENZENEMOXOSULPHONIC ACIDS. PAllT t. 1699

in a fairly pure condition from the final mother liquor ; analysis
pointed to a slight admixture of the monoiodo-derivative :

Found, C = 17-67; 11 = 1-41; 1 = 5909.
CcHsO^NLS requires 0 = 1694; H = ri7; 1 = 59-76 per cent.

lodoaniline-o-sulphonic acid crystallises in shining plates from
much hot water; it is almost insoluble in cold water. It is note-
worthy that the colour of the crystals varies in a rather arbitrary
way, being sometimes buff, often very pale violet, but usually of a
dull grey colour; it has not been found possible to determine what
conditions favour the production of any particular coloured variety,
but there is no doubt of the identity of the differently coloured
substances :

Found, 0 = 24-35; H = 2-08; 1 = 42-41.
OuHcOaNiS requires 0 = 24-08; H = 2-00; 1 = 42-47 per cent.

The yield of pure iodoaniline-o-sulphonic acid amounted to 91 per
cent, of the theoretical.

Constitution of Iodoaniline-o-sulphonic Acid. — It was pointed out
in the theoretical part of this paper that attempts to remove the
sulphonjc group from the di-iodo-acid obtained from the iodoamino-
acid by displacement of the amino-group by iodine were all unsuc-
cessful, and that the relative positions of the iodo- and amino-
or of the two iodo-groups were finally demonstrated by the
preparation of the substance under investigation from a nitroamino-
compound containing these two groups in the para-positions with
respect to each other.

The attempts to remove the sulphonic group consisted in
distilling either the dry acid or a mixture of its potassium salt
with sulphuric acid in superheated steam; a third method con-
sisting in heating a mixture of the acid with concentrated hydriodic
acid in sealed tubes to 170°. In the first experiment, the unchanged
acid was recovered intact; in the second, iodine was evolved, and
tri- and tetra-iodobenzenes were separated from the distillate ; in
the third, very little action took place, the white solid, which
separated from water and melted irregularly from 80° to 130°,
being produced in too small quantities for accurate investigation.
(2^-Di-iodobenzene melts at 129°.)

The p-nitroaniline-/?i-sulphonic acid necessary for the deter-
mination of the constitution of iodoaniline-o-sulphonic acid was
prepared from aniline-m-sulphonic acid by Eger's method (Ber.,
1888, 21, 2581), by acetylating the barium salt and nitrating the
crude product with a mixture of nitric and sulphuric acids. A
yield corresponding with 56 per cent, of the aniline-m-sulphonic acid
was finally obtained.

Conversion of Tp-Nitroaniline-m-sulphonic Acid into o-Iodo-

VOL. xcv. 5 u

1700 BOYLE : THE lODOBENZENEMONOSULPHONiC ACIDS. PARTI.

2-nitrobenz€nesuIpho?2ic Acid. — The amino-compound (1"8 grams)
was dissolved in -warm water, together with a little sodium car-
bonate. The clear solution was poured into about 200 c.c. of dilute
sulphuric acid, and the mixture cooled to 0°. One gram of sodium
nitrite dissolved in water was then added gradually, when a yellow
diazo-compound slowly separated. After the addition of a solution
of 5 grams of potassium iodide, the mixture was warmed on the
water-bath until the evolution of nitrogen was at an end.

On cooling the concentrated solution, j^otassium 5-iorIo-2-nitrn-
heiizenesul'phonate separated in yellow plates. The yield was
theoretical. The corresponding acid has so far been only very
cursorily examined; its chloride and amide have been prepared,
but no analyses have been made.

Conversion of b-Iodo-2-nitrohenzenesul'i)honic Acid into p-7oc?o-
aniline-o-suJjjhonic Acid. — It was anticipated that difficulty would
be experienced in reducing the nitro-group without at the same
time displacing iodine from the nucleus; in point of fact, in many
experiments, the two actions proceeded simultaneously, a mrxture
of the amino- and of the iodoamino-compounds being obtained.
The method eventually used was that described by Claisen and
Thompson (Ber., 1879, 12, 1946), which consists in reducing the
barium salt of the acid with the requisite amount of ferrous
sulphate in the presence of barium hydroxide. It was found,
however, to be more convenient to use the potassium salt of the
iodonitrosulphonic acid, and to reduce this by means of ferrous
sulphate and potassium hydroxide. The nitro-group was reduced
almost quantitatively, the iodine being unaffected. Curiously
enough, in one experiment, when the barium salt was digested with
ferrous sulphate and barium hydroxide, not only was the nitro-
group reduced, but the iodine was also displaced.

Five grams of the potassium salt were dissolved in hot water,
and the solution was mixed with 22 grams of crystallised ferrous
sulphate dissolved in about 250 c.c. of water; the mixture was then
heated on the water-bath, and a solution of 8'9 grams of potassium
hydroxide was added. The black precipitate, which first formed,
was gradually oxidised to the red hydrated ferric oxide; after two
hours' heating on the water-bath and a few minutes over an
ordinary flame, reduction was complete. Concentrated hydrochloric
acid precipitated from the filtered solution a mass of grey
crystals of piodoaniline-o-sulphonic acid. This acid was identified
with that obtained by the action of iodine chloride on aniline-
o-sulphonic acid by displacing the amino-group in both acids by
iodine, and comparing the melting point of the p-di-iodosulphonic
acid produced from the former, and also that of its chloride with

BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI. 1701

similar compounds formed from the latter acid. The melting points
of the two acids were identical (130 — 131°), as were also those of
the chlorides (131 — 132°), so that there is no doubt that when
iodine chloride is passed into a solution of aniline-o-sulphonic acid,
iodine enters into the para-position with respect to the amino-
group : _

^ NnH, — > I<^ ^NHo.

SO3H SO3H

2 : 5-Di-iodobenzenesulphonic acid was prepared in the usual way
from p-iodoaniline-o-sulphonic acid by the diazo-process. Unlike
the other iodoaminosulphonic acids, which yield bright yellow diazo-
compounds, this acid gives rise to a greyish-white or purjDlish-white
substance, differing very slightly in appearance from the original
amino-compound.

After adding potassium iodide, the reddish-yellow liquid was
evaporated to crystallisation ; on cooling, potassium 2 : 5-di-iodo-
benzenesulphonate separated in golden-yellow needles which
became cream-coloured on recrystallisation. The yield of potassium
salt amounted to 84 per cent, of the theoretical. Again, as in the
case of iodoaniline-2;-sulphonic acid, when excess of iodine chloride
is passed into the ortho-acid and no care taken to purify the
resulting iodoaminosulphonic acid, diazotisation involves the
production of a mixture of the potassium salts of the di-iodo- and
tri-iodo-sulphonic acids ; it is not difficult to separate the two, the
latter being practically insoluble in cold, and very sparingly soluble
in hot, water. These potassium salts were recrystallised and dried
at 110° for analysis:

Potassium, ^: 5-Di-iodohenzenesulphonate :

Found, C = 16-07; H=0-67.

C^HyOsIoSK requires C = 1607; H = 0-67 per cent.

rotassium Tri-iodobetizetiesulphonate : Found,*C = 12'48.
CjjHoOglaSK requires C = 12"54 per cent.

When a solution of potassium 2 : 5-di-iodobenzenesulphonate is
mixed with lead acetate, silver nitrate, or barium chloride, thick,
white precipitates of the lead, silver, and barium salts are respec-
tively produced. The acid was prepared by boiling the barium salt
with a slight excess of dilute sulphuric acid; on evaporation of
the filtrate, radiating masses of the acid were obtained in theoretical
yield.

2 : 5 - Z)i - iodobenzenesulphonic acid crystallises in the above way
from water containing a little sulphuric acid ; from water alone, it
crystallises in colourless, transparent plates, which become white

5 u 2

1702 BOYLE : THE lODOBEXZENEMONOSULPHONIC ACIDS. PARTI.

and opaque when left in the desiccator over sulphuric acid. Of
the di-iodosulphonic acids prepared, this is the only one that
separates from water in well-defined crystals. The crystals appear
to contain water of crystallisation, for the air-dried substance
begins to melt at about 80°, but the fusion is not complete until
above 100°, whilst, when dried at 95 — 100°, the melting point is
132°. Further, when dried for some days at 100°, or for a shorter
time at 130°, the material melts approximately at 195°. It is
clear, then, that the acid melting at 80° contains water of crystal-
lisation; that either this water is lost partly at 100° and completely
at 130°, or that it is lost completely at 100°, and the high melting
point of 195° is due to jDartial decomposition, or more probably to
the formation of an anhydride. The correctness of the latter view
has been manifested by the preparation of the anhydride, by
treating the acid either with an excess of phosphorus pentachloride
or with a mixture of this and phosphoryl chloride. It is a white
substance, which melts irregularly at 235 — 245°. On exposure of
the anhydrous acid to air, hydration rapidly occurs, with a con-
sequent lowering of the melting point to 80°. On analysis :

Air-dried material, melting at 80° :

Found, C = 15-53; H = 2-36; H20 = 11-88.
C6H403loS,3HoO requires C = 15-51; H = 2-15; Ho0 = ll-63 per cent.

Acid dried in desiccator over sulphuric acid :

Found, C = 17-03; H = l-84.

Acid melting at 132°: Found, C = 17-25; H = l-40.

Acid heated during several hours at 130°:

Found, C = 17-76; H = l-02.

CGH4O3I2S requires C = 17-56; H = 0-87 pe* cent.

The water of crystallisation was determined (1) by noting the
loss in weight after apiDlication of heat; (2) by neutralising the acid
with standard sodium hydroxide.

2 : 5-Di-iodobenzenesulphonic acid dissolves very readily in water,
moderately in ether, and is almost insoluble in mineral acids. Its
salts all crystallise well.

Sodium 2 : 5-di-iodobenzenesulphonate crystallises from water in
cream-coloured plates, which are anhydrous :

Found, Na = 5-21.

CgH^OglgSNa requires Na = 5-32 per cent.

Solubility. — ^One hundred grams of water dissolve 6-82 grams of
the salt at 22-5°.

lyfad 2 : 5-di-iodobemenesulphonate crystallises in clusters of
white, feathery needles. No absolutely satisfactory determinations
of the water of crystallisation have been made; heating at 147°

BOYLE : THE lODORENZENEMONOSULPHONlC ACIDS. PARTI. 1703

during two hours caused a loss in wciglit corresponding with four
molecules, but on heating to 200°, further loss, which may possibly
be due to slight decomposition, occurred :
Found, H„0 = 6-58.

CioHfPyl4SoPb,4H20 requires HoO^GSG per cent.

SnliihUitij. — One hvindred grams of water dissolve 0'77 gram of
the anhydrous salt at 20°.

Ammonium 2: 5-di-iodobenzenesulphonate is at once precipitated
on the addition of ammonia to a solution of the acid ; on recrystal-
lisation, it separates in long, cream-coloured needles. A comparison
of the ammonium salts of the 3 : 4-di-iodo- and the 2 : 5-di-iodo-
sulphonic acids shows that the two differ enormously in solubility,
the former being so soluble that it is impossible to isolate any
crystals from the aqueotis solution, the latter being even less soluble
than the sodium salt.

Snluhilify. — One hundred grams of water at 20° dissolve 4"35
grams of the salt.

Barium 2: o-di-iodobenzenesuljjhonate crystallises from much
water in long, transparent needles, containing 4| molecules of water
of crystallisation. The salt may be dehydrated by heating to 170°:

Found, Ba = 13-20; HoO = 7-69.
Ci2HcO(;l4S2Ba,4^H20 requires Ba=: 13-22; H20 = 7-81 per cent.

SohihiUty. — One hundred grams of water at 20° dissolve 0-522
gram of the anhydrovis salt.

Potassium 2: 5-di-iodobenzenesulphonate crystallises in long,
colourless needles, containing one molectile of water of crystal-
lisation :

Found, C = 15-36; H = r36; K = 8-27; HoO = 3-99.

CgHaOsIsSKjHoO requires C = 15-45; H = l-12; K = 8-36;
H20 = 3-86 per cent.

The silver salt is only sparingly soluble in water, crystallising in
fine, woolly needles ; the copper salt crystallises in small, pale blue
needles; the cobalt in small, pink, glistening plates; the nickel in
pale green, sparkling plates; the manganese and the cerium in
small, white plates.

2: 5-Di-iodobenzenesulphonyl Chloride. — The chloride, prepared
from the potassium salt, and also from the anhydrous acid, separates
from ether in white needles, melting at 131 — 132°:

Found, 0 = 17-00; H = 0-81.

CeHgOoClIoS requires 0 = 16-80; H = 0-70 per cent.

A mixture of the sulphonyl chloride with the anhydride is obtained
when excess of phosphorus pentachloride or a mixture of pi osphorus
pentachloride and phosphoryl chloride is used in its preparation ;

1704 nOYLE: THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI.

the anhydride being insohible in ether, the separation of the two
is easily effected. The anhydride is a white, amorphous powder,
melting at 235 — 245°; it is stable in air, insoluble in cold water,
partly soluble in hot water, giving an acid solution, and is hydrolysed
on boiling vigorously with alkali ; on boiling with absolute alcohol,
an ester, melting at 113°, is obtained.

2: 5-Di-i()(Iohen~rfiesiiIj)Iiona7)iide. — This is prepared by boiling
the chloride with ammonia ; it is practically insoluble in hot or
cold water, and soluble in alcohol, but it does not crystallise from
this solvent, so that, in order to purify it for analysis, it was boiled
repeatedly with water and dried, first on a porous plate, and then
at 100° :

Found. C = 17-71; H = l-14.

CgHjOoNIoS requires C = 17-60; H = l-22 per cent.

Eflnjl 2 : 5-Di-iodohen~enesitI'pIionafe. — This was prepared by the
action of alcohol on the chloride in presence of sodium hydroxide,
or by treating an ethereal solution of the chloride with sodium
ethoxide in alcoholic solution ; after the addition of water, the
ester was extracted by ether, which, on evaporation, yielded colour-
less needles, melting at 112'5°.

2: d-Di-iodohenzenesuIjihonyl Chloride Bichloride. — On passing a
rapid stream of dry chlorine into a solution of the chloride in
chloroform, a yellow colour is first developed, and after an interval
yellow crystals begin to separate. These form stout, glistening,
yellow needles, melting at 128 — 129°; they liberate iodine from
potassium iodide. On comparing the behaviour of the dichlorides
of 0-, W-, and p-iodobenzenesulphonyl chloride, it is obvious that
the ortho- is much less readily formed than the meta- and para-
coT'npounds; in the present instance, therefore, it may be assumed
that it is the iodine in the meta-position relatively to the sulphonyl
group that becomes tervalent.

03872 Gram liberated iodine equivalent to 15'3 c.c. of
0-0997iV^-sodium thiosulphate :

Found, Active chlorine = 13'70.

CgHgOoClglo requires Active chlorine = 14*21 per cent.

3: ^-Di-iodohenzenesul'pJt.onic Acid.

In order to obtain evidence as to the position occupied by the
second iodine atom in di-iodoanilinc-j^-sulphonic acid, it was neces-
sary to remove the amino-group, and to investigate the nature of
the di-iodobenzenesulphonic acid so produced. This acid was found
to differ from the two which have already been described, and to
be 3 : 5-di-iodobenzenesulphonic acid.

I

BOYLE: TPIE lODORENZENEMONOSULPHONIC ACIDS. PARTI. 1705

Both the methods generally used in removing the amino-group,
namely, that of boiling the diazo-conipound with alcohol, and that
of oxidising the hydrazine derivative, have lieen applied satisfac-
torily.

Method I. — The amino-acid was diazotised in presence of very
slight excess of dilute sulphuric acid, and the diazo-corapound, after
being collected and washed with alcohol, boiled with a large quantity
of methylated spirit under the ordinary pressure ; vigorous evolution
of nitrogen occurred, and during the course of two or three hours
the diazo-compound passed completely into solution, with the pro-
duction of a deep red colour. After removing the excess of alcohol,
sodium chloride was added, and the crude product was boiled with
animal charcoal and recrystallised ; a good yield of sodium di-iodo-
benzetiesiiJ-jylionafe was obtained. It gave an acid melting at 146°,
and a chloride melting in the crude state at 87—88°.

MetJiod II. — The diazo-compound of di-iodoaniline-^j-sulphonic
acid is readily reduced by stannous chloride, a yield of the hydrazine
comjjound amounting to 76 per cent, of the amino-acid being
obtained.

The crude amino-acid (40 grams) suspended in a very slight
excess of hydrochloric acid was diazotised by the requisite amount
of sodium nitrite (69 grams). In experiments with small quantities
of material, it was found more convenient to add slowly to the
cooled acid the mixture of nitrite with the sodium salt of the
substance to be diazotised, but when larger quantities were
employed, it was found impossible sufficiently to dilute the solution
of the sodium salt, so as to prevent the latter from crystallising out,
without producing a rather unmanageable bulk of liquid. The
warm solution of the sodium salt was therefore poured at once
into hydrochloric acid, the amino-acid being precipitated in a fine
state of division. After diazotisation, the solution of the diazo-salt
was poured slowly into a cooled solution of stannous chloride in
concentrated hydrochloric acid, when a thick, white precipitate at
once separated, which, after several hours, was collected, well washed
with cold water, and dried. Examination showed it to consist of
an iodohydrazinobenzenesulphonic acid, probably containing water
of crystallisation. It is practically insoluble in cold water, but
crystallises from much hot water in small, white needles, which,
on being exposed to air during several hours, acquire a slight pink
tinge; it is insoluble in alcohol, reduces Fehling's solution on
warming, reduces an ammoniacal solution of silver nitrate, and is
decomposed by copper sulphate, nitrogen being evolved even in
the cold, and violently on heating.

Four agents, namely, copper sulphate, ferric chloride, potassium

1706 BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI.

chromate, and potassium permanganate, have been used to oxidise
the hj'drazine, but only potassium permanganate is quite satisfac-
tory. Copper sulphate causes removal of the iodine, ferric chloride
gives rise to a substance which still contains nitrogen, but which
has not been further investigated, and potassium chromate causes
removal of part of the iodine with formation of a mixture of
monoiodo- and di-iodo-benzenesulphonic acids.

Potassium Chromate as Oxidising Agent. — The recent work of
Chattaway on the oxidation of aromatic hydrazines (Trans., 1908,
93, 270) seems to show that the best agents to employ for
displacing the hydrazino-grovip by hydrogen are potassium chromate
and potassium permanganate in alkaline solution ; both of these
have been employed successfully. In the case of the foritier, the
following experim^ent was carried out.

Fifty grams of potassium chromate and 5" 7 grams of potassium
hydroxide were dissolved in water, and the solution was heated
almost to the boiling point; 10 grams of the hydrazino-derivative
were then gradually added to the hot liquid, and the heating was
continued until the action, which was at first very vigorous and
was accompanied by much frothing, ceased. After a time, green,
hydrated chromic oxide was precipitated, and the clear, yellow
filtrate deposited crystals of potassium 3 : 5-di-iodobenzenesulphonate
on cooling. On concentrating the mother liquor, crystals of
potassium m-iodobenzenesulphonate were obtained. The first crop
of crystals gave rise ultimately to a di-iodosulphonic acid, melting
at 146°; the second, to an acid which could not be crystallised, and
to an amide which crystallised from hot water in colourless needles,
melting at 148°; it proved, on analysis, to be 7?/-iodobenzene-
sulphonamide :

Found, C = 25-47; H = 2-22.

CgHgOaNIS requires C = 25-48; H = 2-12 per cent.

The melting point of 7?i-iodobenzenesulphonamide is given as
152° by Langmuir, but repeated recrystallisations of the amide
obtained in this experiment did not raise it above 148°.

Potassium Permanganate as Oxidising Agent. — A dilute solution
of 2'4 grams of potassium permanganate and 5 grams of potassium
hydroxide was heated to about 60 — 70°, and 10 grams of the
hydrazine were gradually added ; the addition was continued until
the green colour, which was first developed, disappeared, and
hydrated manganese dioxide made its appearance. The mixture
was then heated until no other solid than manganese dioxide was
present, filtered hot, and the pale yellow filtrate concentrated;
impure crystals of potassium 3 : 5-di-iodobenzenesulphonate (6
grams) were obtained. A second crop from the mother liquor

nOYLE: THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI. 1707

proved identical with the first. The yield amounted to 70 per cent,
of the theoreticah Fractional crystallisation of the product
separated it into two distinct sets of crystals, namely, less soluble
crystals which have not yet been investigated, and more soluble ones
identical with those obtained in method I :

Found, C = 16-16; H^OGG.

CCH3O3I0SK requires C = 16-07; H = 0-67 per cent.

The same di-iodobenzenesulphonic acid may be obtained from
di-iodoaniline-o-sulphonic acid by a similar series of changes.

Di-iodoaniline-o-sulphonic acid gives rise to a hydrazine closely
resembling in appearance that obtained fi'om the jiara-acid. It is
insoluble in cold, and very sparingly soluble in hot, water; it gives
the ordinary reactions of a hydrazine. When oxidised by alkaline
permanganate, it yields a potassium di-iodobenzenesulphonate, from
which an acid, melting at 146°, the melting point of 3 : 5-di-iodo-
benzenesulphonic acid, is readily obtained.

3 : o-Di-todobenzenesiilphonic acid crystallises from faintly acid
solutions in long, radiating crystals, which in the dry state are
almost white. It is very soluble in water, moderately soluble in
ether, from which it separates in white, soapy crystals, and almost
insoluble in mineral acids ; it is freed from adhering sulphuric acid
by precipitation with concentrated hydrochloric acid, the latter
being subsequenth' removed without difficulty. The crystals from
water melt irregularly, beginning at 70°; when dried at 98°, they
melt at 138—146°.

Salts of 3: b-Di-iodnhenzenesulfhonic Acid. — Salts of this acid
have been prepared, but only cursorily examined ; the pofassiitm
salt crystallises in large, white plates, the sodium in white needles,
the ammonium and the barium in fine, colourless needles.

3 : ^-Di-iodohenzenesulphonyl Chloride separates from ether in
small needles, and from a mixture of ether and light petroleum in
clusters of needles, melting at 93° :

Found, C = 16-76; H = 0-71.

CcHgO^ClI.S requires C = 16-80; H- 0*70 per cent.

3: 5-Di-iodobenzenesuIj)honamide is a white powder, insoluble in
hot or cold water; it is extremely difficult to purify, and melts
irregularly from 205 — 218°:

Found, C = 17-58; H = l-36; 1 = 62-00.
CgHANIoS requires 0 = 1760; H = l-22; 1 = 6210 per cent.

2: 4i-Di-iodobenzenesulj)honic Acid,

Two distinct methods have been used in preparing this acid, the
first consisting in preparing 5-nitroaniline-o-sulphonic acid and

170.S BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI.

successively displacing the amino- and nitro-groups by iodine, the
second in removing the amino-group from di-iodoaniline-w-sulphonic
acid by the diazo-reaction. The first method fixes the constitution
of the acid, the second affords some evidence as to the constitution
of di-iodoaniline-OT-sulphonic acid ; of the two, the former, although
involving more operations, is the more convenient, and gives rise
to better yields and purer products.

Method! : rreparafion of o-Iodo--p-nifrobenzencs?dq}homc Acid. —
The 5-nitroaniline-o-sulphonic acid was prepared from 7n-nitroaniline
by Post and Hardtung's method (Ber., 1880, 13, 40; Annalen,
1880, 205, 102), which consists in heating wi-nitroaniline with
fuming sulphuric acid during several hours. As the authors point
out, there is much difficulty in so regulating the conditions of
temperatixre and strength of acid that carbonisation shall not
occur ; in many experiments, when quantities given by the authors
(nitroaniline with five times its weight of fuming acid) were
gradually heated in an oil-bath, the whole mass decomposed at a
temperature far below that given as the temperature of sul-
phouation. It has been found, however, that if the mixture be
kept well shaken, and the oil-bath be gradually heated to 160°,
allowed to cool, and again heated to 160° with constant agitation,
the heating being continued during two or three hours, sulphonation
is complete ; a shorter time than two hours leaves some nitroaniline
unattacked. The acid mixture is neutralised with barium car-
bonate, the brown barium salt collected, purified, and decomposed
with dilute sulphuric acid; the sulphonic acid crystallises out from
the clear filtrate.

21 "8 Grams of this nitroaminosulphonic acid were dissolved in
water with the addition of a little sodium carbonate, the solution
being kept hot and sufficiently dilute to prevent the precipitation
of the sodium salt, which tends to separate as a bright yellow pre-
cipitate ; the clear, hot solution was then poured into excess of
dilute sulphuric acid and the mixture well cooled ; on the gradual
addition of 7 grams of sodium nitrite, the dark yellow colour of
the nitro-compound became much paler, and, on complete diazo-
tisation, a very pale yellow diazo-compound separated from the
acid mixture. After adding 25 grams of potassium iodide, the
mixture was heated on the water-bath until the evolution of
nitrogen was at an end; the cooled filtrate, after concentration,
deposited crystals. These were collected and recrystallised,
separating from water in orange-yellow, shining rhombs, which
consisted of potassium o-iodo-^J-nitrobenzenesulphonate. The yield
amounted to 30 grams, which is approximately 90 per cent, of the
theoretical.

BOYLE: THE lODOHENZENEMONOSULPHONIC ACIDS. PART I. 1709

rrejxD'dtion of m-Iodofnji/irie-p-nulphonir Acid. — A solution of
15 grams of potassium o-iodo-yj-nitrobcnzenesulplionate, with 90
grams of crystallised ferrous sulphate, was heated on the water-
bath, and potassium hydroxide (35"5 grams) was slowly added to
the hot mixture. After two hours' digestion on the water-bath,
reduction was complete ; hydrochloric acid then precipitated a
white, crystalline mass of the iodoanilinesuljDhonic acid from the
concentrated filtrate.

m.-Zo(loa?2ill >i e-p-siflphonic acid crystallises from water in white,
feathery needles ; it closely resembles, in appearance and properties,
the iodoaminosulphonic acids which have been already described.
It is much less soluble in water than the iodonitro-acid from which
it is produced, the addition of mineral acid to a solution of the
potassium salt of the latter causing no precipitation of the
corresponding acid.

The appearance, therefore, of a white precipitate on the addition
of mineral acid may be taken to indicate that reduction has
proceeded satisfactorily ; separation of the amino-acid from any
unchanged nitro-acid is thus easily effected.

Freparation of 2 : 4:-Di-iodobenzenesulphonic Acid. — 7?7-Iodo-
aniline p-sulphonic acid yields a very pale yellow diazo-compound ;
the addition of potassium iodide to a solution of the latter causes
evolution of nitrogen and formation of a reddish solution, from
which potassium 2 : 4-di-iodobenzenesulphonate separates on con-
centration ; this salt crystallises in cream-coloured, shining plates.
The yield is about 70 per cent, of the theoretical. Addition of
barium chloride causes precipitation of the barium salt, and the
latter, when decomposed with sulphuric acid, yields, on concentration
of the solution, the sulphonic acid in shining needles.

Method II. — The second method of preparing the acid involves
the use of di-iodoaniline-??i-sul2Dhonic acid, which is easily obtained
in a pure condition from aniline-m-sulphonic acid.

Attempts to remove the amino-group by boiling the diazo-
compound with alcohol proved unsuccessful; oxidation of the
hydrazine by alkaline chromate yielded, however, satisfactory
results. The hydrazine is obtained as a thick, white precipitate,
which, on keeping, becomes slightly coloured. It is practically
insoluble in hot or cold water and attempts to purify it by recrystal-
lisation from hot water resulted in the production of a slightly
coloured solution, from which no crystals could be obtained; the
substance was purified, therefore, by boiling it several times with
water, after which it was collected and dried. It gives all the
reactions of a hydrazine. Attempts to oxidise the hydrazine with
copper sulphate resulted in the production of cuprous iodide;

1710 BOYLE: THE lODORENZENEMONOSULPHONIC ACIDS. PART I.

oxidation with alkaline chromate gave, however, the desired result.
The same proportions as before were used, and the hydrazine was
added gradually to the hot alkaline solution of potassium chromate ;
violent evolution of nitrogen occurred, and hydrated chromic oxide
was gradually precipitated ; the cooled, concentrated filtrate
deposited crystals of potassium 2 : 4-di-iodobenzenesulphonate.

2: A-Di-hdobenzenesulphonic acid is very soluble in water. It
separates from concentrated solutions in small needles which
contain water of crystallisation ; this is lost after several hours'
exposure in a desiccator, or after a few minutes at 98°. The
anhydrous acid melts at 167° to an opaque liquid, which becomes
transparent at 172°. The dry acid dissolves readily in ether; the
crystals which separate on evaporation of the solvent are very
deliquescent, becoming, however, dry and powdery, and melting at
167°, when dried for a few minutes at 98°. The acid is precipitated
from its aqueous solution by concentrated hydrochloric acid ; use
is made of this property in its purification.

Salts of 2: A-Di-iodobeuzenesidphonic Acid. — The sodium salt
crystallises from water in glistening, white scales, the potassium
salt in sparkling, plate-like needles, the a7nmonium and the barium,
salts in small, white needles. Solubility determinations have not
yet been made, but, owing to the considerable loss entailed in the
preparation of the pure barium salt from the potassium salt, there
is no doubt that the former is considerably more soluble than the
corresponding salts of the isomeric acids.

2: A-Di-iodobenzenesuIphoni/l Chloride separates from ether in
white scales, melting at 77 — 78°; from a mixture of benzene and
light petroleum, it crystallises in rhombic plates:

Found, C = 16-90; H = 0-98.

CgHaOoClIgS requires C = 16-80; H = 0-70 per cent.

The amide prepared (1) from the potassium salt obtained after
removing the amino-group from di-iodoaniline-7?i-sulphonic acid,
(2) from the acid obtained directly from 5-nitroaniline-o-sulphonic
acid, melts at 230°.

3:4: ^-Tri-iodobenzenesiilphonic Acid.

On passing two molecular proportions of iodine chloride into a
dilute solution of aniline-^^-sulphonic acid, di-iodoaniline-p-sulphonic
acid, described by Kalle and Co. (loc. cit.) as a brown substance
rather insoluble in water, is obtained. No difficulty has been
experienced in obtaining it free from the monoiodo-derivative ; it
is an advantage to use a slight excess of iodine chloride, since, as
it is impossible to introduce a third atom of iodine into the nucleus,
the excess simply ensures complete iodination of the acid. It

i

i

BOYLE : THE lODOBENZENEMONOSULPHONlC ACIDS. PARTI. 1711

crystallises from much hot water ; a more convenient method of
purification, however, consists in converting the crude substance
into its sodium salt, and precipitating the amino-acid from a
solution of the latter by the addition of mineral acid. The dis-
placement of the amino-group by iodine, with formation of
potassium tri-iodobenzenesulphonate, is readily brought about.
The diazo-anhydride of di-iodoaniline-p-sulphonic acid is bright
yellow, and is decomposed by potassium iodide at 30°. At that
temperature, nitrogen begins to be evolved, and a line, silky pre-
cipitate takes the place of the somewhat granular diazo-compound,
the precipitate forming a thick scum on the surface of the liquid.
A yield of 13 grams from 10 grams of the amino-acid, amounting
to 97 per cent, of the theoretical, was obtained.

Potassium 3:4: b-ti-i-iodohenztnesul'phonate is insoluble in cold,
and very sparingly soluble in hot, water, from which it crystallises
in small, yellowish-white needles; these were dried at 100° for
analysis :

Found, C = 12-69; H = 0-39; 1 = 66-43; K = 6-76.

CgHoOsIgSK requires C = 12-54; H = 0-34; 1 = 66-38;
K = 6-79 per cent.

The barium, lead, and silver salts are all very sparingly soluble
in water and in hydrochloric, acetic, and nitric acids respectively.
When the barium salt is boiled with excess of concentrated hydro-
chloric acid, it dissolves to a slight extent, and is at once precijiitated
if the solution is cooled ; it is therefore difficult to detect traces of
sulphuric acid or of sulphate in this substance, since the difference in
solubility between barium tri-iodobenzenesulphonate and barium
sulphate is not very marked. As a whole, sparing solubility may
be regarded as characteristic of the salts of this and of the isomeric
tri-iodosulphonic acids. The great stability and insolubility of the
lead salt was demonstrated by an attempt to jorepare the sulphonic
acid from it by decomposition with hydrogen sulphide.

The lead salt was suspended in water, and hydrogen sulphide
was passed through to saturation; after passing the gas during
two or three hours the major portion of the iodo-salt was still
unattacked, and it was not until it had been passed into the
mixture, which was heated at intervals, for two or three days, that
the lead was completely precipitated as lead sulphide, and a clear
solution of the sulphonic acid was obtained on filtration. On
concentrating the solution, needle-like crystals of the acid, melting
at 150 — 157°, were obtained.

In a second attempt to isolate the sulphonic acid, the calcium
salt was heated with the requisite amount of oxalic acid ; no change
in appearance and practically no decomposition occurred.

1712 BUYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI.

A third scries of experiments involved the preparation of the
barium salt and its decomposition with sulphuric acid, and in this
case the acid was obtained without much difficulty. The main
difficulty lies in the preparation of the barium salt, the great
insolubility of the potassium salt rendering its decomposition by
barium chloride a difficult matter when large quantities are being
manipulated. The most satisfactory results were obtained when
the potassium salt was suspended in much water, excess of barium
chloride added, and the mixture boiled during many hours until
the yellow scum of potassium salt had entirely disappeared, and
until the white precipitate collected after repeated washings by
decantation with hot water gave no test for potassium. The '
barium salt was then boiled with excess of dilute sulphuric acid ^
until the crystalline salt had given place to the heavy barium ;
sulphate; on cooling the concentrated filtrate, a mass of glistening
crystals of the sulphonic acid separated.

The acid is extremely soluble in water, moderately so in ether,
and insoluble in acids ; it is best freed from any adhering sulphuric
acid by adding concentrated hydrochloric acid to its aqueous
solution, and treating the precipitated acid as described in the case
of 3 : 4-di-iodobenzenesulphonic acid ; from acid solutions it
crystallises in cream-coloured plates. On account of the difficulty
of obtaining good crystals from water, no attemj^t has yet been
made to determine whether or not it contains water of crystal-
lisation, but, judging from analogy to the two isomeric tri-iodo-
benzenesulphonic acids, and considering the variation in the melting
point as the acid is dried under varying conditions, there is little
doubt that it does. The melting point of the acid (1) precipitated
by mineral acids, (2) separated from ether, (3) crystallised from
water and air-dried, or (4) dried at 95°, is 158°; after being dried
at 125°, it melts at 221°. The latter may therefore be regarded
as the melting point of the anhydrous acid.

Salts of 3: 4 : b-Tri-iodobenzenesulphonic Acid. — The sodium salt
crystallises from water in fine, cream needles, the potassium salt
in small needles, the ammonium salt in long, colourless needles;
the barium, lead, and silver salts have all been obtained b}?^ pre-
cipitation, but have not been prepared in a crystalline condition.

3:4: b-Tri-iodoh enzenesulfhonyl Chloride separates from ether in
small, white needles, and from a mixture of light petroleum and
ether in rhombic plates, melting at 145°:

Found, C = 1319; H = 0-54.

C6H2O2CII3S requires C = 12-98; H = 0-36 per cent.

The amide is a yellowish-white substance, insoluble in hot or
cold water ; it crystallises from methylated spirit in fine, transparent
needles, melting above 250°.

BOYLE : THE lODOBENZENKMONOSULPHONlC ACIDS. PARTI. 1713

The anilide crystallises from alcohol in short, transparent needles,
melting at 201° :

Found, C = 23-73; H = l-42.

C12H8O2NI3S reqviires C = 23-57; H = l-30 per cent.

2:3: 5-Tri-iodobe7izenesulphonic Acid.

It has already been stated that when one molecular proportion of
iodine chloride is passed into a solution of aniline-o-sulphonic acid,
jj-iodoaniline-o-sulphonic acid is produced, which, being insoluble
in water, separates in purplish-grey crystals as it is formed. Owing
to the sparing solubility of this monoiodo-acid great difficulty was
to be expected, and has been experienced, in preparing the di-iodo-
derivative in a state of purity.

Although the preparation of the tri-iodosulphonic acid does not
necessitate the production of a pure amino-acid, the potassium
di-iodo- and tri-iodo-sulphonatcs formed from a mixture of monoiodo-
and di-iodo-amino-acids by displacement of the amino-groups by
iodine being readily separated by fractional crystallisation, it was
thought advisable to determine the conditions favouring the
formation of the more highly iodinated product and to obtain it,
if possible, in a pure state.

The best method of preparing di-iodoaniline-o-sulphonic acid is
to pass excess of iodine chloride into a dilute solution of the mono-
iodo-acid. On adding hydrochloric acid to the solution of the
mouoiodo-acid, the latter began to separate out, but, as iodine
chloride was passed through, this suspended acid gradually dis-
solved ; a clear, reddish-brown solution was obtained, which yielded,
after concentration, a large amount of the desired di-iodo-acid.
This method of preparation involved the use of small quantities
of material ; to prepare the acid on the large scale, it was .found
advisable to precipitate the monoiodo-acid in a fine state of division,
and then to pass iodine chloride through the suspended material,
with frequent agitation, until the grey crystals of the monoiodo-
gave place to the heavyj violet needles of the di-iodo-acid ; these
were collected and dried.

The acid yields a bright yellow diazo-compound, which is decom-
posed by potassium iodide, with the production of flaky crystals
of potassium 2:3: 5-tri-iodobenzenesulphonate. The yield of
potassium salt is theoretical.

The barium, lead and silver salts, obtained by precipitation
from the potassium salt, are all very sparingly soluble in water;
the same difficulty, therefore, attends the preparation of the pure
barium salt and of the acid from the barium salt as in the case
of 3 : 4 : 5-tri-iodobenzenesulphonic acid. The potassium salt must
be boiled for a long time with excess of barium chloride before

1714 BOYLE : THE lODOBENZENEMONOSULPHONIC ACIDS. PARTI.

complete decomposition occurs; the barium salt must then be
boiled with excess of sulphuric acid until, on evaporating the clear
filtrate, an acid is obtained which leaves no residue when heated
on platinum foil.

From a mineral acid solution, the sulphonic acid separates in
shining crystals, which dissolve readily in water, less readily in
ether, and are almost insoluble in mineral acids; from water alone,
they crystallise in colourless plates, which become rather coloured
when exposed to air. The melting point of the air-dried material
was found to vary somewhat irregularly; it was visually 166 — 170°,
sometimes 183"^, and once above 200°. One can only account for
these variations by assuming that the acid, which contains water of
crystallisation, loses this gradually; consideration of the melting
points obtained when the acid is dried at diffei'ent temperatures
confirms this assumption. When recrystallised from water and
examined at once, the melting point is 166 — 170°; when dried at
95°, it is 183°; and when dried at 135°, it is 210—215°. Analyses
showed that it probably crystallises with three molecules of water;
166 — 170° is therefore the melting point of the hydrated, and
210 — 215° that of the anhydrous material :

1"2191 lost 0'1137 HoO when heated during several hours at
135°. HoO = 9-32".

0011303138, SHoO requires H^O — 9*15 per cent.

Salts of 2:3: b-Tri-iodohenzeiiesul-pJionic Acid. — The sodium,
'potassium, and aynmoiiium salts obtained by neutralisation, and the
lead, barium, silver, copper, manganese, nickel, and cobalt salts
obtained by precipitation have all been prepared. The sodium salt
crystallises in transparent needles, the ammonium salt in white
needles, and the potassium salt in shining plates; of the others,
the barium and silver salts are extremely difficult to crystallise,
the lead salt separates in small, woolly needles, the copper salt in
pale blue plates, the nickel salt in small, green needles, the cobalt
salt in pink plates, and the manganese salt in fine, white, feathery
needles.

2:3: 5-Tri-iodobenze7iesulphoni/l Chloride separates from ether in
small, white needles, and from a mixture of benzene and light
petroleum in long, transparent needles, melting at 122 — 123°:

Found, C- 13-01; H = 0-42.

CcHgOsClIyS requires 0 = 12-98; H = 0-36 per cent.

The amide is a white powder, insoluble in hot or cold water, and
very sparingly soluble in alcohol ; it does not melt below 280°.

Ethyl 2:3: b-tri-iodobtnzenesulplionate was prepared from the
sulphonyl chloride by treating it with absolute alcohol in the
presence of excess of sodium hydroxide. It separates from ether
in clusters of needles, melting at 110°:

BOYLE: THE lODOBENZENEMONOSULPHONlC AClDS. PART I. 1715

Found, C = 16-91; H = l-35.

CgH^O.JaS requires C = 1702; H = l-24 per cent.

2:4: 5-Tri-iodobenzenesul2)honic Acid.

In Kalle and Co.'s jiatent (Inc. cit.), it was stated tliat the
passage of two molecular proportions of iodine chloride into a
solution of aniline-w-sulphonic acid containing a little hydrochloric
acid resulted in the formation of di-iodoanilinem-sulphonic acid,
which separated out as it was formed. No mention was made of
any monoiodoaniline-?n-sulphonic acid, and the conclusion was
therefore drawn that such a substance could not be isolated under
these conditions. It was not, therefore, until quite recently, after
the di-iodo-derivative had been converted into the tri-iodosulphonic
acid and subjected to investigation, that any attempt was made to
discover whether the mono-derivative could be obtained^ and, if so,
what conditions favoured Its production. It will be seen from
the theoretical part of this paper that a knowledge of the con-
stitution of nionoiodoaniline-?n-sulphonic acid is useful in fixing
the constitution of the di-iodo-derivative, and, consequently, of the
tri-iodosulphonic acid formed from it; it seems advisable, therefore,
to give experimental details of its preparation here when substances
prepared from aniline-w-sulphonic acid are being discussed.

In one experiment, slightly less than one molecular proportion of
iodine chloride was passed into a very dilute solution of aniline-
?n-sulphouic acid (S'6 grams in 2 litres of water), and the dark brown
liquid was kept for several hours; a violet colour was gradually
developed, and, on cooling the concentrated solution, yellowish-
brown crystals separated ; these, after being diazotised and treated
with potassium iodide, yielded crystals of potassium 3 : 4-di-iodo-
benzenesulphonate in an impure condition. The acid obtained from
this salt melted irregularly at 115 — 117° (3: 4-di-iodobenzene-
sulphonic acid melts at 122 — 125°), the low melting point indicating
that some amino-acid had probably escaped iodination in the first
instance, and that the final product was therefore a mixture of
the di-iodo- with some monoiodo-sulphonic acid. The conversion of
a fresh quantity of the potassium salt, dried at 100°, into the
chloride, afforded convincing evidence of its constitution; the
chloride crystallised from a mixture of light petroleum and benzene
in transparent needles, which became white and opaque when left
in a desiccator over sulphuric acid, and melted sharply at 82°, the
melting point of 3 : 4-di-iodobenzenesulphonyl chloride.

There is no doubt, therefore, that when iodine chloride acts on
aniline-wz-sulphonic acid, a monoiodo-derivative is formed, in which
the iodine atom occupies the position ortho- and para- to the amino-
and sulphonic groups respectively; the second iodine atom, as has

1716 r.OYLE : THE lODOBEKZENEMONOSULPfloNtC AClDS. PART 1.

already been shown, enters the para-position witli respect to the
amino-group. Di-iodoaniline-/«-sulphonic acid yields a yellow diazo-
compound, which is decomposed by potassium iodide, with formation
of 2:4: 5-tri-iodobenzenesvilphonic acid, which separates from the
hot solution in shining crystals of the potassium salt. The pre-
l^aration of the barium salt and of the acid from the barium salt
are matters of little difficulty, the acid separating on evaporation
of its aqueous solution in shining plates. It dissolves very readily
in water, more sparingly in ether, and is almost insoluble in
mineral acids; the crystals from water melt sharply at 182°; when
dried at 100°, or at 125°, they melt at 230°. Analysis showed
that the acid melting at 182° contains three molecules of water of
crystallisation :

Found, C = 12-32; H = l-69; HoO = 914.
CoH303l3S,3H.O requires C = 12-20; H = l-50; HoO = 9-15 per cent.

Salts of 2: 4: d-Tri-iof/obenzcjiesuljilionic Acid. — The soJiuin and
yntassiuiii salts crystallise in long, white needles; the aitunon'nuti
salt in small, white nodules; the jJotassiiim salt crystallises with one
molecule of water :

Found, C = 12-34 ; H = 0-6G ; ILO = 334.
C^HoOsIgSK.H.O requires 0 = 12-10; H = 0-67; H._,O = 3-04 per cent.

2:4: d-Tri-iodohtnze/iesuIjjho/it/I Chloride crystallises from ether
in small needles, and from a mixture of light petroleum and ether
in small, sparkling crystals, melting at 135°:

Found, C = 12-96; H = 0-40.

CgH.OoClIaS requires 0 = 1298; H = 0-36 per cent.

The amide is a yellowish-white powder, insoluble in water, but
soluble in methylated spirit; it does not melt below 260°:

Found, 0 = 13-45; H = 0-70; 1 = 71-21; N = 2-37.

C6Hi0.2l3NS requires 0 = 13-45; H = 0-74; 1 = 71-21;
N = 2-61 per cent.

The an Hide crystallises from alcohol in small, needle-shaped
crystals, melting at 194—196°:

Found, 0 = 23-67; H = l-49.

OJ2H8O.2I3NS requires 0 = 23-27; H = l-31 per cent.

My thanks are due to Professor H. E. Armstrong, through whose
suggestion the work arose; to Miss E. E. Field, for kind help and
encouragement during its progress; and to Miss M. Tutin, for
valuable help in the preparation of material and in the analysis of
salts.

Royal Holloway College,
Enolkfielt) Grern.

INTERACTION OF CHLORINE AND HYDROGEN 1717

CLXXXVII. — The Injluence of Gaseous Oxides of
Nitrogen on the Rate of Interaction of Chlorine
and Hydrogen.

By David Leonard Chapman and Patrick Sarsfield MacMahon.

Hitherto it has been shown that both oxygen (Bunsen and Roscoe,
Phil. Trans., 1857, 147, 390) and niti-ogen chloride (Burgess and
Chapman, Trans., 1906, 89, 1399) retard the union of hydrogen and
chlorine in light, and that, although the inhibitive influence of
the former is considerable, that of the latter is incomparably
greater. On the other hand, the observed retardation of the same
reaction by nitrogen and carbon dioxide was so small that we have
been forced to conclude that these gases function as diluents only.
The fact that the property of inhibiting the union of hydrogen and
chlorine is strictly limited to a few substances, and is not possessed in
varying degrees by gases in common, suggests that it is the result of
some chemical relation, definable in general terms, between the gas
exhibiting the property and one of more of the constituents of the
interacting system. It is possible that the inhibitor must be
capable of reacting with one or more of the other gases present.
Such a condition is obviously satisfied by oxygen and nitrogen
chloride.

As this conjecture is supported by facts recently disclosed in
the study of the effect of the gaseous oxides of nitrogen on the
rate of union of chlorine and hydrogen, it is advanced tentatively
as a hypothesis which will at least serve to indicate the line of
investigation that we intend to pursue.

In the presence of water, nitric oxide and chlorine interact,
and a bi'own gas, probably nitrogen peroxide, results. A con-
siderable period of time elapses before the last trace of this gas
is absorbed by the chlorine water in the vessel containing it. If a
comparatively small volume of nitric oxide is introduced into a
mixture of chlorine and hydrogen, the resulting brown gas inhibits
the interaction of the chlorine and hydrogen in the light. When,
on standing for several hours, the nitrogen peroxide has dissolved,
the electrolytic gas almost recovers its former sensitiveness. In its
power to retard the interaction of chlorine and hydrogen, nitrogen
peroxide appears to lie between nitrogen chloride and oxygen.
Like oxygen, nitrogen peroxide will, under the conditions necessary
for the interaction of chlorine and hydrogen, act on hydrogen
chloride, so that it belongs to that class of substances to which the
property of inhibition is supposed to be limited.

VOL. XCV. 5 X

1718 CHAPMAN AND MACMAHON :

Nitrogen monoxide, altliougli an oxidising agent, acts merely
as a diluent. Nitrous oxide is, however, an extremely stable and
inert substance at the ordinary temperature. It is probable that
it will only part with its oxygen at elevated temperatures.

The three known inhibitors, therefore, contain either loosely
combined atoms of oxygen or loosely combined atoms of chlorine.
They are all three capable of oxidising hydrogen chloride, and if
it is assumed that a comparatively large amount of energy is
dissipated in the process of oxidation, an intelligible explanation is
afforded of the means by which the inhibitor is enabled to discharge
the efficient energy of the chlorine.

The facts published in our last paper on the retarding effect of
oxygen (this vol., 959) are in complete harmony with the theory.
The communication in question contained experimental evidence
which pointed to the conclusion that a very* small (perhaps an
infinitely small) amount of light energy was sufficient to cause the
union of considerable amounts of chlorine and hvdrogen in a
mixture of the gases containing no oxygen or other inhibitor. On
the other hand, to oxidise with gaseous oxygen an equivalent
quantity of hydrogen chloride in the presence of chlorine, must
necessitate the expenditure of a considerable amount of efficient
energy. It is, therefore, not surprising that oxygen, although an
inhibitor, is not removed from a mixture of hydrogen and chlorine
at a measurable rate in the presence of light.

Experimental.

The apparatus was the same as that employed to measure the
retarding effect of oxygen. The electrolytic gas was so free from
inhibitive impurities removable by the action of light that no
induction period could be observed when the actinometer filled with
the mixture was exposed to light. The nitric oxide w-as prepared
by the action of dilute nitric acid on a saturated solution of ferrous,
sulphate, and was collected in a large gasholder filled with water.
After standing in the presence of the water for several hours, some
of the gas was allowed to pass into a smaller gasholder filled with
a boiled solution of sodium arsenite, in the presence of which
reagent it was allowed to remain for several days in order to remove
any nitrogen chloride which might be present. As the light emitted
from the standard Hefner lamp was inconveniently feeble for these
experiments, an electric glow-lamp of 25 c.p., placed at a distance
of 2 metres from the insolation vessel, was substituted for it.
Under the influence of the light from this lamp, the index of the
actinometer moved at the rate of 40 cm. in one minute. A measure

INTERACTION OF CHLORINE AND HYDROGEN 1719

of nitric oxide, equal to 1 /300th of the total volume, was admitted.
The mixture was then exposed to the light of the glow-lamp for
half an hour, during which period there was no detectable movement
of the index. If the original mixture had been exposed to the
light for the same length of time, about one-third of the electrolytic
gas would have been converted into hydrogen chloride. After the
illumination of half an hour, the mixture was allowed to stand in
the dark for two and a-half hours, and then re-exposed to light;
during twenty-five minutes there was no combination. The
actinometer was then left for thirteen hours in the dark. On
exposure to light there was instantaneous formation of hydrogen
chloride. The movement of the index was at first slow, but it
gradually increased until the sensitiveness of the mixture was
almost as great as that observed before the nitric oxide had been
added.

In a second experiment the procedure was slightly varied. Fresh
water was introduced into the actinometer, which was subsequently
filled with sensitive electrolytic gas. The index liquid moved
34 cm. in one minute when the insolation vessel was exposed to
the light of the glow-lamp ; but after the mixture had been left for
almost twelve houi-s in darkness, the nitrogen peroxide had almost
completely disappeared from the gas. The sensitiveness, which
was at first only 3 cm. per minute, increased gradually and rather
irregularly to its original value.

In a third experiment it was found that a mixture of the
same composition began to combine after five hours' continuous
exposure to light. A soluble product of the interaction of moist
nitric oxide and chlorine, presumably nitrogen peroxide, is there-
fore capable of inhibiting the combination of chlorine and hydrogen.

In the experiments with nitrous oxide, some difficulty was pre-
sented in the preparation of the gas sufficiently pure for our
purpose. Very small quantities of foreign substances in the
ammonium nitrate, from which the nitrous oxide is prepared, tend
to facilitate side reactions when the salt is decomposed by heating.
The ammonium nitrate was therefore crystallised four times from
pure water. In the preparation of the nitrous oxide, great care
should be taken to prevent rapid decomposition of the salt. In
spite of the precautions taken to ensure purity, we have not suc-
ceeded in preparing a sample of the gas quite free from nitric oxide.

In the experiments performed to test the influence of the nitrous
oxide on the rate of interaction of chlorine and hydrogen, the
source of light was a Hefner lamp, placed at a distance of 60 cm.
from the insolation vessel of the actinometer. The details of an
experiment are recorded below.

6x2

1720 BARGER AND WALPOLE : FURTHER SYNTHESES OF

The sensitiveness of the electrolytic gas was 4"40 cm. per minute.
After adding to the electrolytic gas 1/ 300th of its volume of nitrous
oxide, it was found that hydrogen chloride was still formed in the
light, the rate of its formation corresponding to a movement of
the index of 036 cm. per minute. On standing for 12"5 hours in
darkness, the sensitiveness was 2 "30 cm. per minute, but it rose
gradually to 400 cm. per minute. That the observed retardation
immediately after the addition of the nitrous oxide was not caused
by the nitrous oxide itself, but by a small amount of nitric oxide,
is evident from the circumstance that the effect almost entirely
disappeared after the insolation vessel had been allowed to remain
in darkness for half a day. Another experiment, in which a volume
of nitrous oxide equal to as much as l/20th of the internal capacity
of the insolation vessel was added, furnished similar results.

Conclusions.

1. A gaseous product of the interaction of moist chlorine and
nitric oxide (presumably nitrogen peroxide) inhibits the interaction
of chlorine and hydrogen.

2. The inhibitive gas is after several hours almost completely
absorbed by the chlorine water.

3. Nitrous oxide is a mere diluent. The rate of interaction of
chlorine and hydrogen is not appreciably affected by the presence
of a comparatively large volume of the gas.

4. It is considered as probable that the action of the inhibitor is
such that the efficient energy of the chlorine derived directly from
the light is dissipated by its bringing about a chemical change in
which the inhibitor takes part.

The Sir Leolike Jenkins Laboratories,
Jesus College,

OXFOKD.

CLXXXVIII. — Further Syntheses of ^-HydroxyphenyU

ethylamine.

By George Barger and George Stanley Walpole.

One of us described recently (Trans., 1909, 95, 1123) the isolation
of a new physiologically active principle of ergot, its identification
as p-hydroxyphenylethylamine, and its synthesis by the reduction
of p-hydroxyphenylacetonitrile. On account of the therapeutical'

I

P-HYDROX YPHENTLETH YLAMINE. 1721

interest of the substance, other syntheses were attempted, and two
of these form the subject of the present paper.

In the first place, the introduction of a phenolic hydroxyl group
into phenylethylamine was attempted. By nitrating benzoyl-
phenylethylamine, a j^-nitro-derivative was readily obtained, and
this yielded by successive reduction and diazotisation the iV^-benzoyl
derivative of the desired substance, which was readily converted
into y-hydroxyplienylethylamine itself by heating with acids.
Instead of benzoylation, we also used acetylation as a means of
protecting the amino-group, but in this case the jj-nitro-derlvative
is not so readily separated from its isomerides. Phenylethylamine
can also be nitrated in the form of its benzylidene derivative when
dissolved in concentrated sulphuric acid, but the mixture of nitro-
compounds, which results on dilution with water, cannot be
separated except by acetylation or benzoylation.

The second synthesis to be described starts from anisaldehyde,
which was converted into p-methoxyphenylpropionic acid. This
acid, first prepared by W. H. Perkin, sen. (Trans., 1877, 31, 411),
is more readily obtained by the method given by Perkin, jun., and
Robinson for 3 : 4-dimethoxyphenylpropionic acid (Trans., 1907,
91, 1071). The amide of this acid, MeO-CoH^-CHg-CHg-CO-NHo,
yielded by Hofmann's reaction j9-methoxyphenylethylamine,
MeO'C6H4'CH2'CHo'NI-l2, from which the methyl group was finally
removed by heating with hydrobromic acid.

Experimental.

I. — Synthesis of ■^-Hydroxxj'phenylethylaimne from
Phenylethylamine.

Benzoyl-p-nitrophenylethylamine, N02'CgH4'CH2*CH2'NHBz, was
prepared by slowly adding benzoylphenylethylamine (8 grams) to
fuming nitric acid (40 grams), the temjierature being kept below
5°. After pouring on snow, the product solidified. On crystal-
lisation from alcohol, 3'4 grams of the j^ara-compovind separated in
long needles ; the mother liquor contains isomeric nitro-compounds,
which are much more soluble.

Benzoyl-p-nitrophenylethylamine was obtained pure by a second
crystallisation from alcohol, and then melted at 162°. It is
moderately soluble in boiling alcohol, but only sparingly so in cold
alcohol :

0-2573 gave 22-2 c.c. No (moist) at 11° and 748 mm. N = 10-0.
C15HJ4O3N2 requires N = 10-4 per cent.

1722 BARGER A\D WALPOLE : FURTHER SYNTHESES OF

Benzoyl-^-am'ino'phenyJethylamine, NH2'C6H4*CH2*CH2*NHBz,

Benzoyl-2>-nitroplienylethylamine (13"5 grams) is suspended in
100 c.c. of alcohol, tinfoil (11 grams) is added, and then gradually
50 c.c, of concentrated hydrochloric acid. The temperature is at
first kept below 50° ; finally the reaction is completed on the water-
bath. When all the tin has dissolved, the solution is filtered, and
the alcohol is removed by steam distillation. On cooling, the hydro-
chloride of the amino-compound separates. The free base was
obtained by rendering the solution alkaline and extracting with
ether. It forms crystals, melting at 134°:

0-3183 gave 31-4 c.c. No (moist) at 17° and 759 mm. N = ll-5.
CisHjgONj requires N = ir6 per cent.

The hydrocJiloride melts and decomposes above 280°, and is very
sparingly soluble in water :

0-2677 gave 0-1376 AgCl. CI=12-7.

Ci5HjeONo,HCl requires CI =^12-7 per cent.

Benzoyl-'p-7iydroxyp7ienylet7iylamine, HO*CgH4"CH2*CH2'NHBz.

To a boiling solution of the amino-compound in dilute sulphuric
acid, a solution of sodium nitrite was slowly added in equivalent
proportion. The hydroxy-compound formed is almost insoluble in
water, and separated out; it was collected and crystallised from
alcohol, when it formed hexagonal plates, melting at 162°:

0-1300 gave 6-5 c.c. Ng (moist) at 15° and 750 mm. N = 5-8.
CJ5H14O2N requires N = 5-8 per cent.

On heating with 20 per cent, hydrochloric acid to 140°, this
substance is hydrolysed, yielding p-hydroxyphenylethylamine ; on
benzoylation by the Schotten-Baumann method, the dibenzoyl
derivative, melting at 170°, is formed.

Acetyl-p-nitropkenylethylamine, NOo'CgH^'CHg'CHo'NHAc, is
prepared by adding acetylphenylethylamine to nitric acid in the
same way as was described for the benzoyl compound. After
pouring on snow, the acetyl derivative, unlike the benzoyl
derivative, remained liquid. The solution was therefore extracted
■with ether, and the ethereal solution was washed with sodium
carbonate to free it from nitric acid, dried, and evaporated. Very
little methyl alcohol was added to the syrupy residue; on keeping
in a vacuum desiccator, crystals were slowly deposited, which were
pressed on a porous tile, and recrystallised from methyl alcohol;
they then melted at 142° :

i

P-HYDROXYPHENYLETHYLAMINE. 172,3

0-1326 gave 0-2836 COo and 00712 H..0. C-58-2; H = 5-9.

00869 „ 10-2 c.c. No "(moist) at 19° and 762 mm. N = 13-5.
CioHjoOgNo requires C=^57-8; 11 = 5-8; N = 13-5 per cent.

Tlie nitrocompound thus obtained was reduced, the crude amino-
compound diazotised, and the resulting solution was concentrated
until it contained about 30 per cent, of sulphuric acid, and heated
to 140°. 29'Hydroxyphenylethylamine was then extracted by amyl
alcohol and isolated as the dibenzoyl derivative (m. p. 169 — 170°),
but none of the intermediate compounds were characterised.

^-yUrophcnyhlJtylaminc, NOo-CgH^'CHg'CH.^-NH,.

This substance is readily obtained, mixed with its isomerides,
when benzylidenephenylethylamine, CHoPh'CHo'NICHPh (melt-
ing at about 70°; prepared by warming the components), is nitrated
in sulphuric acid solution by the addition of the calculated quantity
of potassium nitrate. On diluting with water and removing, by
steam distillation, the benzaldehyde formed, a yellow oil remains,
which, on acetylation and benzoylation, yields the ^^-nitro-
derivatives (melting respectively at 142° and 162°), which have
been described above. The benzoyl derivative was hydrolysed by
heating with ten times its weight of concentrated hydrochloric acid
to 170° for four hours. jj-Nitrophenylethylamine was thus obtained
as a yellow syrup, which could not be crystallised, and was readily
soluble in most organic solvents. It absorbed carbon dioxide from
the air, forming a crystalline carbonate. The hydrochloride forms
leaflets, melting at 214°, and was analysed :

0-2141 gave 0-1522 AgCl. Cl = 17-6.

CsHjqOoNojHCI requires CI = 17-5 per cent.

II. — Synthesis of ^-Hydroxyphenylethylamine from Anisaldehyde.

The p-methoxyphenylpropionic acid reqiiired was prepared
according to the same method as that employed by Perkin and
Robinson (Trans., 1907, 91, 1079) for the preparation of 3 : 4-di-
methoxyphenylpropionic acid.

Anisaldehyde (100 grams) was condensed with ethyl acetate (245
grams) by means of finely-divided sodium (245 grams). After one
hour, 102 grams of potassium hydroxide, dissolved in methyl
alcohol, were added; after removal of the alcohol by distillation,
the solution was treated with 3000 grams of 2\ per cent, sodium
amalgam. The resulting methoxyphenylpropionic acid was crystal-
lised from water; yield 46 grams, melting point 104°,

1724 FURTHER SYNTHESES OF P-HYDROXYPHENYLETHYLA.MINE.

■p-Methox^phenj/Ipropionamide, MeO*C6H4*CH2*CH2*CO*NH2.

The acid obtained above (46 grams) was heated on a water-bath
with one molecular pro^^ortion of phosphorus pentachloride in
chloroform solution until no more hydrogen chloride was evolved.
On fractionally distilling the mixture, 30 grams of f^-methoxy-
phejiylpropionyl chloride, boiling at 161 — 165°/ 15 mm., were
collected. Gaseous ammonia was passed into the ethereal solution
of the chloride, and gave a quantitative yield of the amide, which
crystallised from alcohol in prisms, melting at 124° :

0-1009 gave 7-2 c.c. No (moist) at 24° and 758 mm. N = 8-0.
CjoHigOoN requires N = 7'8 per cent.

■p-Methoxyphenylethylamine, MeO*C6H4'CH2*CH2*NH2.

The amide (27 grams) was heated with 7*9 c.c. of bromine
dissolved in 150 c.c. of water containing 36"5 grams of sodium
hydroxide, the temperature not exceeding 55°. On extraction of
the base with ether, drying, and fractionally distilling, 8 grams
of y-methoxyphenylethylamine, boiling at 138 — 140°/ 20 mm., were
obtained. The base forms a colourless liquid, very sparingly soluble
in water. On passing hydrogen chloride into the ethereal solution
of the base, a crj-stalline hydrochloride, melting at 206°, was
obtained :

0-0946 gave 0-0717 AgCl. CI = 18-8.

C9Hi30N,HCl requires 01 = 188 per cent.

05 Gram of the above hydrochloride was heated for four hours
to 160° with 5 c.c. of hydrobromic acid (D 1*4). On cooling, a
salt crystallised out, but could not be readily freed from the mother
liquor ; the excess of hydrobromic acid was therefore removed under
diminished pressure, and the remaining solid boiled in alcoholic
solution with charcoal. On adding ether to the filtrate, a salt
separated which gave Millon's reaction; after benzoylation, the
dibenzoyl derivative of ^^-hydroxyphenylethylamine, melting at
169 — 170°, was isolated.

The Wellcome Physiological Research Laboratories,
Hekne Hill, London, S.E.

THE PREPARATION OF DISULPHIDES. PART VII. 1725

CLXXXIX. — The Preparation of DisuJi^liides. Part VII.
The Nitrohenzyl Mercajytans and Disul2^hides.

By Thomas Slater Price and Douglas Frank Twiss.

In an earlier paper (Trans., 1908, 93, 1402), the authors have
described the preparation of the three nitrobenzyl disulphides
(ortho, meta, and para) by the action of sodium carbonate on the
solution of the corresponding alkyl thiosulphate compound. How-
ever, although the properties of the o- and 7n-disulphides agreed
well with those described by jDrevious observers (Cassirer, Ber.,
1892, 25, 3029; Gabriel and Posner, Ber., 1895, 28, 1025; Gabriel
and Stelzner, Ber., 1896, 29, 161; Lutter, Ber., 1897, 30, 1069;
Blanksma, Fee. trav. chim., 1901, 20, 137), the j^-nitrobenzyl
disulphide obtained was entirely different from the substance which
Strakosch describes as this compound {Ber., 1872, 5, 692).

The method of preparation described by Strakosch is to mix
p-nitrobenzyl chloride with ammonium sulphide in alcoholic solution,
when, according to his statement, the mercaptan first separates,
and this, on further treatment with ammonium sulphide, gives the
disulphide. This statement cannot be correct, for the following
reasons, (a) The melting point of the mercaptan (140°) is given
as being higher than that of the disulphide (89°). {h) O. Fischer
{Ber., 1895, 28, 1337) has shown that the action of alcoholic
ammonium sulphide on p-nitrobenzyl chloride yields much ^J-nitro-
benzyl monosulphide (m. p. 159°), and although he suggests that
Strakosch's mercaptan is really this compound, he does not appear
to have further studied the matter, (c) Otto and Rossing {Ber.,
1886, 19, 3129) have shown that the action of potassium sulphide on
an organic disulphide in alcoholic solution gives the mercaptan by
reduction, {d) In a recent paper (Schaeffer and Murua, Ber.,
1907, 40, 2007), p-nitrobenzyl mercaptan is mentioned as having
the melting point 51°.*

A repetition of Strakosch's experiment showed us that the product
of the reaction is really a mixture of the sulphide, disulphide, and
mercaptan of T^-nitrobenzyl, and we have assured ourselves of the
true character of the ^'■^it'^ot)enzyl disulphide (m. p. 126"5°)
obtained by us previously, in the following manner. Under the
action of mineral acids, the sodium alkyl thiosulphates yield the
corresponding mercaptans (Bunte, Ber., 1874, 7, 646; Purgotti,

The details regarding this substance are given in an Inaugural Dissertation by
"Waters (Munich, 1905)^ a copy of which we have not been able to examine.

1726 PRICE AND TWISS:

Gazzetta, 1890, 20, 25) ; by this reaction, we have obtained the
ortho-. meta-, and para-mercaptans from the three sodium nitro-
benzyl thiosulphates. From these niercaptans the corresponding
disulphidcs were prepared by oxidation with iodine, and found to
be identical with the compounds we had previously obtained by the
action of alkali on the three sodium nitrobenzyl thiosulphates.
The only one which was doubtfi;l, in the light of Strakosoh's results,
was the p-disulphide, but any doubt is now removed.

The mercaptans are formed from the alkyl thiosulphate com-
pounds by hydrolysis with acids (Bunte, loc. cit.) according to the
equation : RSoOgNa + HoO = RSH + NallSO^.

This reaction was used by Bunte in support of the formula
NaS'SOo'ONa, which is usually assigned to sodium thiosulphate.
Gutmann {Ber., 1909, 42, 228) has recently shown, however, that
in the course of the reaction disvilphide and sulphur dioxide are
produced at the same time as the mercaptan and sulphate. He
considers that these results disprove Bunte's interpretation of the
reaction, and he explains them by the intermediate formation of
the hypothetical compound thioethyl hydroperoxide, CoHj'S'OH,
which he has also assumed to be formed in other reactions (Ber.,
1908, 41, 1650). At the same time, he throws doubt on the con-
stitutional formulae usually assigned to sodium thiosulphate and
to sodium sulphite. We have previously shown (Trans., 1908, 93,
1395; Ber., 1908, 41, 4375) that the usually accepted formulae give
a satisfactory explanation of all Gutmann's results, and that there
is no valid evidence for the existence of the thioethyl hydro-
peroxide; we cannot see that Gutmann's recent results afford any
fresh evidence in the matter. That he has found disulphide and
sulphur dioxide to be formed in the hydrolysis of sodium and
potassium ethyl thiosulphates is readily explained by the thermal
decomposition these compounds undergo (compare Bunte and
Purgotti, loc. cit.). If an aqvieous solution of sodium ethyl thio-
sulphate, or even of sodium benzyl thiosulphate, which is much
more stable, is heated for some time, disulphide and dithionate are
formed according to the equation :

2NaO-02S-SR = R2S2 + NaO-S02-SOo-ONa.

In the presence of acids, the dithionate is decomposed with the
evolution of sulphur dioxide. This reaction is subsidiary to the
ordinary hydrolytic one, but will account for all Gutmann's results.

Experime:^tal.

The method of preparation and purification of the mercaptans
was practically the same in each case. Ten grams of the nitro-
benzyl chloride and 15 grams of sodium thiosulphate were heated

THE PREPARATION OF DISULPHIDES. PART VII. 1727

together in 30 c.c. of alcohol (95 per cent.) and 30 c.c. of water
under reflux for approximately one hour. The clear solution was
allowed to cool, after which the sodium nitrobenzyl thiosulphate,
which crystallised out, was collected and washed with a little
alcohol. The thiosulphate compound, without further purification,
was dissolved in water, and the solution filtered if not quite
clear.* After the addition of 7 c.c. of concentrated sulphuric acid,
the solution was maintained at a temperature just below its boiling
point for about eight hours, by which time the mercaptan had
separated as an oil. The yield of the crude mercaptan was
approximately 80 per cent. ; it could be slightly increased by longer
heating. In order to remove the disulphide, which contaminated
the crude product, the mercaptan was distilled in an atmosphere of
carbon dioxide under diminished pressure. The purity was then
tested by titration, in alcoholic solution, with iT/lO-iodine (compare
Klason and Carlson, Ber., 1906, 39, 738).

o-Nitrohenzyl mercwptan forms pale yellow crystals, which melt
at 29'5° to a yellow liquid which distils at 149'5°/15 mm. Gabriel
and Stelzner \Ber., 1896, 29, 161) give 42—44°; in all probability
their product was contaminated by much disulphide. Oxidation
with iodine gave the disulphide, melting at 110°:

0"27o8 required 16'22 c.c. of i\'/10-iodine for complete oxidation.
M.W. = 170-1.

C^I-IA^^'S requires M.W. = 1691.

Tn.-Nitrohenzyl jnercapfan is a bright yellow liquid at the ordinary
temperature; it distils at 164°/ 18 mm. It can be obtained in the
form of pale yellow crystals, which melt at 14°. Lutter (Ber., 1897,
30, 1069) gives 11 — 12°. On exposure to the air, the liquid
oxidises very slowly. Oxidation with iodine gave the disulphide,
melting at 103° :

0"4684 required 2750 c.c. of iV/lO-iodine for complete oxidation.
M.W. = 170-3.

C^H^O.NS requires M.W. = 169-1.

"p-Nitrohenzyl mercaptan forms yellow needles, which melt at
52-5°. Schaeffer and Muriia {Ber., 1907, 40, 2007) give 51°. It
distils at 164°/ 15 mm. Recrystallisation was not a satisfactory
method of purification, on account of unavoidable oxidation which
took place. Oxidation with iodine gave the disulphide, melting
at 126-5°:

0-3454 required 20-40 c.c. of iV/10-iodine for complete oxidation.
M.W. = 169-3.

C7H-O2NS requires M.W. = 1691.
Any turbidity was due to the presence of disulphide, which had been formed
by the thermal decomposition of the alkyl thiosulphate.

1728 THE PREPARATION OF DISULPHIDES. PART VII.

The nitrobenzyl mercaptans have faint characteristic odours, that
of the para-compound being the least pleasant. With an alcoholic
solution of lead acetate, the ortho- and para-compounds give an
orange-red precipitate ; the meta- gives a primrose-yellow precipitate
under the same conditions.

Action of Ammonium Sulphide on Tp-Nitrobenzyl Chloride.

Three c.c. of an approximatel)'^ 30 per cent, ammonia solution
were dissolved in 40 c.c. of alcohol (95 per cent.), and the solution
was saturated with hydrogen sulphide. A warm alcoholic solution
of 5 grams of ^>nitrobenzyl chloride was added, when almost imme-
diately needle-shaped crystals began to separate, and hydrogen
sulphide was evolved. After five hours, the crystals (A) were col-
lected. They were recrystallised from pyridine, and then from
alcohol, the melting point after the recrystallisations being 155° and
156 — 157° respectively:

0-2400 gave 0-1942 BaSO^. S = ll-1.

C14H10O4N2S requires S = 10-5 per cent.

The melting point and the analysis indicate that this substance
was almost pure ji-nitrobenzyl sulphide. O. Fischer gives the
melting point as 159°.

On the addition of hot alcohol to the mother liquor from the
recrystallisation of the sulphide from pyridine, cream-coloured
crystals were obtained, which melted at 115 — 130°. The percentage
of sulphur in these crystals (14-8 per cent.) indicated a mixture
of disulphide and monosulphide. (The monosulphide requires
S = 10'5, and the disulphide S = 19-0 per cent.)

On the addition of water to the mother liquor from which the
last-mentioned solid had separated, a precipitate was obtained which
melted at 53 — 55°, and consisted chiefly of jj-nitrobenzyl mercaptan.
After oxidation with iodine in alcoholic solution, and without
further purification, the crystals obtained melted at 124-5°; they
were obviously the slightly impure para-disulphide.

After the first lot of crystals (A) had been collected, the mixture
deposited more solid after a few days. Determinations of the
melting point (125°) and of the sulphur content of this solid, after
recrystallisation from a mixture of alcohol and pyridine, showed it
to consist mainly of 2'-nitrobenzyl disulphide :

0-3587 gave 0-5050 BaS04. S = 19-3.

C14HJ2O4N2S2 requires 8 = 190 per cent.

On further keeping for a mouth or so, the mother liquor again
deposited more solid, which, after recrystallisation from a mixture

THE BENZYL AND NITROBENZYL SELENOSULPHATES, ETC. 1729

of alcohol and pyridine, melted at 120 — 122°. Like the previous
solid, this appeared to be chiefly yj-nitrobenzyl disulphide :

0-1602 gave 02239 BaSO^. S = 19-2.

C14H12O4N2S0 reqviires S = 190 per cent.

The product of the interaction of ammonium sulphide and
3?-nitrobenzyl chloride is therefore evidently a mixture containing
the disulphide, monosulphide, and mercaptan.

We desire to express our thanks to tlie Research Fund Com-
mittee of the Chemical Society for a grant which partly defrayed
the expenses of the foregoing investigation.

Chemical Department,

Municipal Technical School,
Birmingham.

CXC. — The Benzyl and Nitrohenzyl Selenosulphates
and the Benzyl and Nitrohenzyl Diselenides.

By Thomas Slater Price and Lionel Manfred Jones.

The chief methods which have hitherto been used for the prepara-
tion of organic diselenides are : (a) Oxidation of the seleno-
mercaptans; (h) action of potassium diselenide on the potassium
alkyl sulphates ; (c) treatment of the monoselenide with selenium ;
{d) action of sodium diselenide on the alkyl halides; (e) action of
selenium on the Grignard compounds. In many cases diselenides
are formed as by-products in the preparation of the seleno-
mercaptans and monoselenides. (For literature see : Jackson,
Annalen, 1875, 179, 1; Chabrie, Ann. Chim. Phys., 1890, [vi], 20,
202; Taboury, Ann. Chun. Phys., 1908, [viii], 15, 1; Wuyts, Bull.
Soc. chim., 1909, [iv], 5, 405; Tschugaeff, Ber., 1909, 42, 49;
Doughty, Amer. Chem. J., 1909, 41, 326. These papers also give
full references to earlier work.)

In a preliminary note (Proc, 1908, 24, 134) we have shown how
the method employed by Price and Twiss (Trans., 1907, 91, 2021,
and succeeding papers) for the preparation of disulphides could
be extended to the preparation of diselenides. A solution of
sodium selenosulphate was obtained by digesting selenium with a
solution of sodium sulphite and filtering from the undissolved
selenium. On adding this solution to an alcoholic solution of
benzyl chloride, a turbid liquid was obtained, which, however, soon
cleared when heated on a water-bath under reflux. After a short

1730 PRICE AND JONES : THE BENZYL AND NITROBENZYL

time a small quantity of a yellow oil separated, wliicli, after
removal from the remainder of the liquid, solidified on cooling;
this was proved to be benzyl diselenide. Further quantities of the
disolenide could be obtained from the mother liquor, either by
electrolysis in a divided cell, or by the addition of sodium carbonate.

In the course of further work, an attempt was made to extend
the above method to the preparation of the nitrobenzyl diselenides.
It was found, however, that the solution obtained on heating
sodium selenosulphate with p-nitrobenzyl chloride was very
unstable. After a very short time, decomposition took place with
the separation of much selenium, and it was only with great
difficulty that the diselenide could be isolated. Various changes in
the method of procedure were tried, but without success. Even
when the heating was stopped as soon as the contents of the flask
had become clear, and the solution rapidly cooled, decomposition
took place after a time. The difficulty was finally overcome by
using potassium sulphite in place of sodium sulphite. Rathke
{J. 2^/-. Chem., 1865, 95, 8) found that potassium selenosulphate is
more stable in solution than the corresponding sodium salt, and
this is apparently true for the alkyl derivatives of these salts.

The method of procedure when potassium sulphite was used was
similar to that already indicated with sodium sulphite. The use
of this salt had the further result that the various potassium alkyl
selenosulphates were readily isolated. When the turbid liquid,
which resulted from mixing the solution of potassium seleno-
sulphate and the alcoholic solution of the alkyl chloride, was heated
over a flame under reflux, the contents of the flask cleared in two
or three minutes, and, after a few minutes longer, a precipitate of
the potassium alkyl selenosulphate began to form. The reaction
between the potassium selenosulphate and the alkyl halide is
complete in a very short time, and consequently the heating was
not continued for longer than ten minutes.* At the end of that
time the contents of the flask were rapidly cooled, with the result
that the precipitate of the alkyl selenosulphate became much more
bulky — at all events, in the case of the nitrobenzyl derivatives.
This precipitate always contained some diselenide mixed with it,
especially in the case of the benzyl compound. In our preliminary
note we stated that this was probably formed according to the
equation :

2RSe-S02-OK = RgSeg + K2SO4 + SOg,

since some sulphur dioxide was evolved at the same time, but w^e
are now of the opinion that this does not represent the true course

* Prolonged heating, even with the potassium compounds, brought about do-
compositioa with the hberation of selenium.

SELENOSULPHATES AND DISELENIDES. 1731

of the reaction. Bunte (Ber., 1874, 7, 646) and Purgotti {Gazzetta,
1890, 20, 25) have shown that the alkyl thiosulphates undergo
thermal decomposition with the formation of disulphides and
dithionate, and it has also been noticed by one of us, in conjunction
with Mr. D. F. Twiss, that solutions of sodium benzyl thiosulphate
become cloudy on prolonged heating, the cloudiness being caused
by the formation of benzvl disulphide. The selenium compounds
are less stable than the corresponding sulphur compounds, and
consequently thermal decomposition takes place to a greater extent,
as represented by the equation :

2KO-SOo-SeR = RoSeo + KO-SOo-SOo-OK.

The evolution of sulphur dioxide was only noticed in the pre-
paration of benzyl diselenide, and then only when sodium seleno-
sulphate was used. Its formation was probably due to hydrolysis
of the sodium benzyl sclcnosulphate by water,

R-Se-S02-0Na + H2O = RSeH + NaHS04,

and the subsequent action of the sodium hydrogen sulphate on the
excess of sulphite present, or on the dithionate resulting from the
thermal decomposition.

The mother liquor remaining after the precipitate of the
potassium alkyl selenosulphate had been collected still contained
considerable quantities of that compound. It was not recovered as
such, but the diselenide was prepared from it in one of two ways.
The most general method was hy the action of iodine, dissolved
either in alcohol or in potassium iodide solution, at the ordinary
temperature. The reaction takes place very quickly, and proceeds
quantitatively according to the equation :

2KO-S02-SeR + 2H2O + 1. = R2Se2 + 2KHSO4 + 2HI.

The second method was by electrolytic reduction in a divided cell,
after potassium hydrogen carbonate had been added to the solution
(compare Price and Twiss, Trans., 1907, 91, 2021). It is note-
worthy that not only could benzyl diselenide be prepared by the
electrolytic method, but also p- and 7«-nitrobenzyl diselenides,
whereas the corresponding nitrobenzyl disulphides could not be
obtained in this way (compare Trans., 1908, 93, 1401). The
o-nitrobenzyl diselenide could only be prepared by the iodine
method ; electrolysis led to the deposition of selenium, no diselenide
being formed, probably because of steric hindrance, as was pointed
out in the case of the corresponding o-disulphide.

All the selenium which passes into solution to form selenosulphate
is recovered, either as the potassium alkyl selenosulphate or in the
form of diselenide; that is, the yields obtained, as far as the

1732 PRICE AND JONES: THE BENZYL AND NITROBENZYL

selenium is concerned, are quantitative. We have not investigated

the respective yields of the alkyl selenosulphates and the diselenides.
The melting points of the diselenides prepared are given in the

following table, and, for comparison, those of the corresponding

disulphides :

Diselenides. Disulphides.

Benzyl 92—93° 71".

o-Nitrobenzyl 103-5 109-5

m-Nitrobenzvl 106 0 103-0

^-Nitrobenzyl 107-5 126-5

It will be seen that in the case of the diselenides the substitution
of the benzyl by the nitrobenzyl group has a considerably less effect
than in the disulphides, and also that the influence of the position
of the nitro-group is not so marked. Moreover, 7n-nitrobenzyl
diselenide has a higher melting point than the corresponding ortho-
compound, whereas in the case of the disulphides the order is
reversed. It is also noteworthy that, although the substitution of
sulphur by selenium raises the melting point of the benzyl com-
pounds by 21 — 22°, the melting point of the w-nitrobenzyl compound
is only raised by 3°, while the melting points of the o- and p-nitTO-
benzyl compounds are lowered by 6° and 19° respectively.

The potassium nitrobenzyl selenosulphates are much more easily
prepared than potassium benzyl selenosulphate, since they are much
less soluble in water. In this respect they are very similar to the
corresponding thiosulphates (Price and Twiss, Trans., 1908, 93,
1401). All the selenosulphates and diselenides prepared are more
or less slowly acted on by light, with the liberation of selenium.
The benzyl compounds are the least, and the r?i-nitrobenzyl com-
pounds the most stable.

Experimental.

Since the potassium nitrobenzyl selenosulphates were isolated
before the corresponding benzyl compounds, they will be described
first, together with the corresponding diselenides.

Potassium -p-Nitrobenzyl Selenosulphate, KO'S02'Se*C7Hg'N02.

2-3 Grams of finely powdered selenium were boiled with a solution
of 6 grams of potassium sulphite in 50 c.c. of water for three-
quarters of an hour, and the hot solution filtered * from the small
amount of selenium remaining undissolved ; 5 grams of p-nitrobenzyl

* In most cases the filtrate remained clear on cooling to the ordinary tempira-
ture, but sometimes there was a very slight precijntate of selenium, which, however,
did not affect the further treatment with the alkyl chloride, as it immediately
dLsapjieared on wanning. When sodium sulphite was used in the place of
potassium rsulphite, much selenium was precipitated as soon as the solution wa»
cooled.

SELENOSULPHATES AND DISELENIDES. 1733

chloride, dissolved in 50 c.c. of alcohol (95 per cent.), were then
added, and the resulting turbid solution was heated over the free
flame under reflux. The turbidity disappeared in a very short
time, but after about five minutes a precipitate began to form. The
heating was continued for ten minutes,* and then the contents
of the flask rapidly cooled. A copious precipitate, consisting chiefly
of potassium p-nitrobenzyl selcnosulphate, but containing also small
quantities of 2;-nitrobenzyl diselenide and some potassium chloride,
sulphate, and sulphite, was thereby produced. The inorganic salts
were eliminated by recrystallising the precipitate several times from
95 per cent, alcohol. The traces of diselenide remaining were then
removed by well shaking the recrystallised substance several times
with ether, leaving the pure potassium ^^nitrobenzyl selenosulphate.

Potassium p-nit/ohetizi/l selenosulyhate crystallises in plates,
which are fairly soluble in water. In the bulk, the salt possesses
a slight creamy tinge. On exposure to diffused daylight for some
days, it is decomposed, with the liberation of selenium. The
solution gives no precipitate with barium chloride ; with sodium
carbonate or sodum hydroxide, a yellow precipitate of the diselenide
is produced. Hydrochloric acid gives a yellow precipitate, which
consists of a mixture of the seleno-mercaptan and the diselenide;
the precipitate forms slowly in the cold, but more quickly on
warming. An alcoholic solution of iodine, or a solution of iodine in
potassium iodide, gives an immediate precipitate of the diselenide.

The attempts to analyse this salt by estimating the potassium as
sulphate were not very satisfactory. When heated very gently,
either alone or after the addition of sulphuric acid, decomposition
took place very rapidly with the liberation of selenium, and it was
very difficult to regulate the decomposition so that no loss of salt
occurred. It was found that the best method of jjrocedure was
to heat the salt alone until decomposition was complete, and then
treat the residue with concentrated sulphuric acid. The potassium
sulphate so obtained did not contain any selenium :

0-9144 gave 0-2342 KoSO^. K = 11-49.

C.HgOsNSKSe requires K = 11-69 per cent.

The most satisfactory method of analysis was one which depended
on oxidation with iodine, which, as already indicated, takes place
according to the equation :

2K0-S02-Sell + 2HoO + 1, = RoSeg + 2KHSO4 + 2HI.

The method of procedure was as follows. A weighed amount of
the salt was dissolved in water and a slight excess of iodine in

* In the first experiment in which potassium sulphite was used, the heating was
continued for a longer time. After about twenty minutes the contents of the flask
suddenly became red, owing to the copious deposition of selenium.

VOL. XCV. 5 Y

1734 PRICE AND JONES: THE BENZYL AND NITROBENZYL

potassium iodide solution added. There was an immediate pre-
cipitate of the diselcnide, and the end of the reaction was indicated
by the rapid settling of the precipitate. The reaction was hastened
by warming to a temjierature of about 45° after the iodine had
been added. The diselenide was collected, and well washed with
hot water in order to remove all acid present. The iodine in the
filtrate was then removed by careful addition of sodium thiosulphate,
and the acid determined by titration with standard alkali. From
the amount of acid liberated during the reaction, the percentage
of potassiiim could be calculated. It was not found practicable
to carry out the estimation by determining the amount of iodine
used in the oxidation :

0-7531, after oxidation, required 3303 c.c. of 0-1366./\^-NaOH.
K = ir71.

C^HcO^NSKSe requires K = 11-69 per cent.

l)-M t robe 712 tjl Diselenide, (N02'C(;H^*CH2)2Se2.

This was prepared from the filtrate and mother liquors obtained
in the prejDaration and recrystallisation of the potassium ^'-nitro-
benzyl selenosulphate. An alcoholic solution of iodine was added
until the colour of the iodine persisted, and then water, in order
to precipitate the last traces of diselenide from the alcoholic solution.
The diselenide was then recrystallised from alcohol, a drop of
sulphurous acid being added to remove any iodine.

In one experiment the filtrate obtained in the preparation of
potassium jj-nitrobenzyl selenosulphate was electrolysed at the
cathode in a divided cell (compare Price and Twiss, Trans., 1907,
91, 2021), after the addition of 6 grams of potassium hydrogen
carbonate. A rotating cathode (area = 0-5 sq. dcm.) was used, and
0'25 ampere passed for one hour, and 0'5 ampere for another hour.
A copious precipitate of the diselenide was formed. The filtrate
from this precipitate, on standing in the dark overnight, gave a
deposit of selenium. This was collected, and the filtrate again
electrolysed, but there was only a further deposit of selenium.

It "was also proved that the precipitate formed by the addition
of sodium carbonate to an aqueous solution of potassium ^^-nitro-
benzyl selenosulphate consists of the diselenide, but it is not as
pure as that obtained by iodine oxidation or by electrolysis.

\>-Nitrohenzyl diselenide, on recrystallisation from alcohol, gives
a felted mass of canary-yellow crystals, which melt at 107-5°. On
exposure to diffused daylight for some days it gradually
turns red, owing to the liberation of selenium. With alcoholic
sodium hydroxide it gives no immediate colour in the cold, but

I

SELENOSULPHATES AND DISELENIDES. 1735

a deep red colour on warming (compare the corresponding di-
sulphide, Trans., 1908, 93, 1401).

The selenium was determined by the method of Frerichs (Arch.
Phar/n., 1902, 240, 65G) :

03218 required 29-63 c.c. i\710-potassium thiocyanate. Se = 36-46.
0-2051 gave 12-10 c.c. N._, (moist) at 17° and 739 mm. N = 6-62.
CiJ-IjoO^NoSco requires Se = 36-79; N-^6-51 per cent.

Potassium m.-Nitrohenzyl Selenosulphate.

This was prepared from r«-nitrobenzyl chloride in a similar way
to the corresponding para-compound, using the same quantities of
reagents. It crystallises in colourless plates, which are fairly readily
soluble in water, and are more readily obtained pure than the
para-compound. Selenium is liberated on exposure to light :

0-5137, after oxidation, required 22-51 c.c. of 0-1366.y-NaOH.
K=ll-70.

CjHgOsNSKSe requires K = 11-69 per cent.

ra-Nitrohenzyl Diselenide.

This was obtained from the m-nitrobenzyl selenosulphate by
oxidation with iodine, in a similar manner to that already described
for the 2;-diselenide. It could also be prepared by electrolytic
reduction of the selenosulphate. It crystallises from alcohol in
flat needles, which possess only a very faint yellow tinge, and melt
at 106°. It is much more stable towards diffused daylight than
the j'-diselenide, but on prolonged exposure it gradually acquires
a red tinge. With alcoholic sodium hydroxide it gives a red
colour on warming :

0-3050 required 28'55 c.c. iV/10-potassium thiocyanate. Se = 37-08.
0-3868 gave 23-20 c.c. No (moist) at 19-2° and 734-9 mm. N = 6-62.
Ci4Hi204N.2Se2 requires Se = 36-79; N = 6-51 per cent.

Potassium o-Nitrohenzyl Selenosulphate.

This is prepared in a similar manner to the para- and meta-
compounds, and possesses similar properties. It crystallises from
alcohol in colourless plates :

0-4423, after oxidation, required 1940 c.c. of 01366T-NaOH.
K = ll-72.

CyHgO^NSKSe requires K = ir69 per cent.

5 Y 2

1736 PRICE AND JONES: THE BENZYL AND NITROBENZYL

o-Xitrohenzijl Diselenide.

This was prepared from the potassium o-nitrobenzyl seleno-
sulphate by oxidation with iodine, exactly as described for the
para- and meta-compounds. It could not be obtained by electro-
lytic reduction of the selenosulphate. It crystallises from alcohol
in yellow plates, which melt at 103"5°. It is about as sensitive to
light as the para-compound. With alcoholic sodium hydroxide, it
gives a deep red colour on warming :

0"2877 required 32"15 c.c. A"'/10-potassium thiocyanate. Se = 36*85.

0-2116 gave 12-30 c.c. No (moist) at 20° and 756 mm. N = 6-58.
Ci4Hio04N2Se2 requires Se = 36-79; N = 6-51 per cent.

Potassium Benzyl Selenosulphate, KO'S02*Se'CH2*C6H5.

The solution of this substance was prepared in a similar manner
to that used for the nitrobenzyl compounds, the quantities taken
being 3 grams of selenium, 8 grams of jDotassium sulphite, 40 c.c.
of water, and 40 c.c. of alcohol. Owing to the ready solubility of
the salt in water, however, the qitantity of precipitate which
separated on cooling was very small ; also, since potassium benzyl
selenosulphate is much less stable than the corresponding nitro-
benzyl salts, the precipitate contained a large proportion of the
diselenide. In order to remove the diselenide, the solution, together
with the precipitate, was extracted with ether. The aqueous layer
was then evaporated to dryness over concentrated sulphuric acid
in a vacuum, and the potassium benzyl selenosulphate extracted
from the residiie by boiling with 95 per cent, alcohol. The crystals
which separated from the alcoholic extract on cooling were, however,
by no means pure. In the preparation of the potassium seleno-
sulphate, some sulphite remains unacted on by the selenium, and
this, to some extent, forms potassium benzylsulphonate with the
benzyl chloride. Repeated crystallisation from alcohol is necessary
to purify the benzyl selenosulphate from the benzyl sulphonate.

Potassium henzyl s el en o sulphate crystallises in colourless plates,
which are very readily soluble in water. On exposure to light,
decomposition readily takes place with liberation of selenium. The
solution gives no precipitate with barium chloride. Oxidation with
iodine gives the diselenide, but this reaction cannot be used for
the analysis of the salt, since the diselenide does not settle readily,
and excess of iodine seems to facilitate decomposition, with libera-
tion of selenium. The best method of determining the percentage
of potassium is to decompose the salt by gentle heat — the decom-
position does not take place violently, as in the case of the

SELENOSULPHATES AND DISELENIDES. 1737

nitrobenzyl compounds — and then treat the residue with concen-
trated sulphuric acid. This method is also a good test of the
purity of the salt. If it is quite pure, heating alone gives
potassium sulphate, the weight of which is not altered by treatment
with sulphuric acid, whereas, if potassium benzylsulphonate is
present, the residue left after heating contains potassium sulphite:

0-3024 gave 0-3189 COo and 0-0764 HoO. C = 28-76 ; H = 2-83.
0-5017 „ 0-1521 K0SO4. K = 13-66.
CjH^OySKSe re(iuircs"'c = 2902; H = 2-44; K = 13-51 per cent.

Benzyl Diselenide, (CgH5*CH2)2Se2.

This was prepared from potassium benzyl selenosulphate, either
by oxidation with iodine, or by electrolytic reduction. For the first
method, the alcoholic mother liquors obtained in the recrystal-
lisation of the potassium benzyl selenosulphate were generally used.
After excess of iodine had been added, the diselenide remaining
in solution was precipitated by the addition of water. It was
collected immediately and recrystallised from alcohol, since, as has
already been pointed out', the presence of iodine seemed to facilitate
the decomposition, with liberation of selenium. When recrystal-
lising, a drop of sulphurous acid was added to remove any iodine
present, and it was also necessary to wash the crystals well with
water to remove any traces of hydriodic acid before they were
dried.

For the electrolytic method, an aqueous solution of potassium
benzyl selenosulphate was used, the method of procedure being
similar to that described for p-nitrobenzyl diselenide. The strength
of current was 0-25 to 0'5 ampere.

Benzyl diselenide crystallises from alcohol in yellow needles, which
are slightly deeper in colour than those of /j-nitrobenzyl diselenide,
and melt at 92 — 93°. Jackson {Ajinalen, 1875, 179, 1) describes
the crystals as lustrous, yellow plates, melting at 90°. It is possible
that the compound he obtained was not quite pure, since we have
found that the slightly impure crystals have properties agreeing
with those described by Jackson, even to the melting point. This is
especially the case when the crystals are obtained from a con-
centrated alcoholic solution.

Benzyl diselenide is very sensitive to light as compared with the
nitrobenzyl compounds. An exposure of an hour or so to diffused
daylight turns it red :

0-2122 required 24-77 c.c. T/10-potassium thiocyanate. Se = 46-2.
Cj^Hj^Seo requires Se = 46-5 per cent.

1738 PYMAN: ISOQUINOLINE DERIVATIVES. PART III.

We desire to express our thanks to the Research Fund Com-
mittee of the Chemical Society for a grant which has partly
defrayed the expenses of the foregoing investigation.

Chemical Department,
Municipal Technical School,

BlUMINGHAM.

CXCI. — isoQuinoUiie Derivatives. Part III. The

Oxidation of Substituted 1-BenzyItetrahydroiso-
quinolines.

By Frank Lee Pyman.

It has long been known that narcotine and hydrastine yield, on
oxidation with manganese dioxide and sulphuric acid, opianic acid
and cotarnine and hydrastinine respectively. The following scheme
represents the degradation of narcotine to cotarnine ; hydrastine
differs only from narcotine in being devoid of the methoxy-group
in the 8-position of the isoquinoline ring:

CH, . CH„ CHO

^ CH <^\ I V^2 + I P^^^

MeO CHO OMe

OMe
The author has recently shown (this vol., pp. 1266 and 1610) that
laudanosine is also amenable to the same type of degradation,
yielding 4 : 5-dimethoxy-2-/3-methylaminoethylbenzaldehyde and
veratraldehyde according to the equation :

CHO

MeOf Y ^CHg _ . MeO| , yxxs ,

MeO^^^]!^Me MeOl^^^^ NHMe '^^^OMe

OHO OMe

. lOMe
OMe

PYMAN: ISOQUINOLINE DERIVATIVES. PART III. 1739

whilst T-benzoyltetrahydropapaverine gives rise, under similar con-
ditions, to 6 : 7-dimethoxy-3 : 4-dihydro/,soquinoline, veratraldehyde,
and benzoic acid :

CH CH

I

jOMe
OMe

It was thus shown that this method of oxidation is applicable
to the cleavage, not only of l-opianyltetrahydro/.soquinolines, that
is to say, of compounds in which the carbon atom joining the
isoquinoline and benzene rings is already partly oxygenated, but
also of certain l-vcratryltetrahydro/soquinolines, compounds in
which the two rings are connected by a methylene group.

In view of these results, it seemed desirable to apply this method
of oxidation to a further number of substances of similar con-
stitution to those already investigated, with the view of deter-
mining the scope of its aiDplication in respect of the nature of the
substituent groups. Furthermore, it seemed likely that the method
might be capable of somewhat general application, and consequently
of value in the elucidation of the constitution of a number of
naturally occurring alkaloids of at present undetermined structure.
This refers particularly to some of the rarer opium alkaloids, with
regard to Avhich there is strong reason to believe that they are
substituted 1-benzyltetrahydro/^oquinolincs.

'^-Ethi/ltetrahydro'pajKiverine and ^-'propyltetrahydropapaverine,
when oxidised with manganese dioxide and sulphuric acid, undergo
the same type of change as does laudanosine, yielding veratraldehyde
and 4: 5-dimethojcy-2-fi-ethylaminoethylbe7izaldehij<le (I) and 4: 5-
dimethoxy-2-^-2jro'pylaminoethylhenzaldehyde (II) respectively ;

MeO's^^'^ NHEt MeOl^^l^ NHPr

CHO CHO

(I.) (II.)

these compounds and a number of derivatives, of which
details will be found in the experimental part of this paper,
behave similarly to the corresponding methyl homologues obtained
from laudanosine. Further, tetrahydropapaverine, like its

1740 pyman: isoquinoline derivatives, part III.

i)'-benzoyl derivative, yields on oxidation 6 : 7-dimethoxy-3 : 4-di-
liydro/c<oquinoline and veratraldeliyde. It is therefore clear that
the course of this reaction is uninfluenced by the character of the
side-chain attached to the niti'ogen atom, since this may be either
a hydrogen atom, an alkyl or an acyl group.

It must be remarked that up to this point, in the case of all
those substances which have undergone the type of change instanced,
the substituent in the 1 -position has been either the opianyl (nar-
cotine, hydrastine) or the veratryl residue (tctrahydropapaverine
derivatives). It therefore seemed of interest to apply this oxidation
to bases containing other groups in this position in order to
determine whether the presence of a benzyl group was an essential
factor. For this purpose, 1-benzylhydrocotarnine and the 1-alkyl-
hydrocotarnines, which arc readily prepared by Freund and Reitz's
method (Ber., 1906, 39, 2219), appeared to be suitable.

It was found that 1-benzylhydrocotarnine (III) readily under-
went the same type of change as in the cases previously instanced,
yielding cotarnine (IV) and benzaldehyde :

9^2 _^ CH,<nl I V^2 + C-HgO

'NMe \/\ ^HMe ^ '

MeO CH MeO CHO

CH,Ph

(III.) " (IV.)

On the other hand, 1-ethylhydrocotarnine (V) and 1-propylhydro-
cotarnine (VI) :

^ 0\^y\/NMe " O^y^/NMe

MeO CHEt MeO CHPr

(V.) (VI.)

after oxidation under similar conditions, were to a large extent
recovered unaltered, and cotarnine could not be isolated from the
products of the reaction. It would, therefore, appear that the
presence of a benzyl group in the 1-position is an essential factor
for the cleavage under these conditions of substituted tetrahydro-
i-soquinolines containing a hydrocarbon substituent in the 1-position.
In this connexion, it is interesting to note, however, that in certain
cases, where there is no substituent in the 1-position, substituted
2-alkyltetrahydroisoquinolines readily yield the corresponding sub-
stituted 2-)8-alkylaminoethylbenzaldehydes on oxidation ; thus,
hydrocotarnine yields cotarnine, hydrohydrastinine yields hydrasti-
nine, and it has now been found that 6 : 7-dimethoxy-2-methyltetra-

MeOi A /T<iM« ^ MeO

PYMAN: ISOQUINOLINE DERIVATIVES. PART III. 1741

hydroj.soquinoline (VII) yields 4 : 5-dimethoxy-2-)8-methylamino-
ethylbenzaldehyde (VIII) :

CH,3 CH2

NHMe
CHO

(VII.) (VIII.)

The formation of cotarnine in this manner led Frennd and Beck
{Ber., 1904, 37, 1942) to attempt tlie preparation of 2-^-methyl-
aminoethylbenzaldehyde by the oxidation of 2-methyltetrahydro-
isoquinoline ; they did not, however, obtain this compound, but a
higher oxidation product, 1:3: 4-triketo-2-mcthyltctrahydro?so-
quinoline.

In view of the general nature of the results obtained by the
oxidation of 1-benzyltetrahydro/soquinolines, it appeared probable,
however, that l-^-methylaminoethi/lhenzaldehyde (IX) would be
obtained, together with benzaldehyde, on the oxidation of 1-benzyl-
2-methyltetrahydroisoquinoline (X), and this proved to be the case :

CH-CH,Ph CHO

(X.) " (IX.)

The latter reaction is of special interest, since l-benzyl-2-methyl-
tetrahydro?8oquinoline, which has recently been described by
Freund and Bode {Ber., 1909, 42, 1763), is the parent substance of
a number of alkaloids, for instance, narcotine, hydrastine, and
laudanosine, whilst 2-)3-inethylaminoethylbenzaldehyde is the parent
substance of their degradation products, cotarnine, hydrastinine,
and 4 : 5-dimethoxy-2-i8-methylaminoethylbenzaldehyde respectively.

2-j8-Methylaminoethylbenzaldehyde possesses properties, for the
most part, similar to those of the alkyloxy-substituted 2-j8-methyl-
aminoethylbenzaldehydes ; for instance, it readily yields an acetone
condensafiofi jfi'oduct (XI or XII; compare this vol., p. 1268), and

CHg-CHg-NHMe NHMe-CHj-CH.,
CH^CH CO CH=CH

(XI.)

CH,

CH2 H^C-
NMe MeN\ /\/
CH-CH,-CO-CH.rCH
(XII.)

174'2 PYMAN : ISOQUINOLINE DERIVATIVES. PART III.

forms salts of 2-mcfliyl-Z: A-diln/droisoqninoIiiiium hydroxide (XIII)
by substitution ; further, aqueous solutions of its salts yield, with
potassium cyanide, l-cya7io-2-methyl,tetrahydroisoquinoline (XIV),
a compound insoluble in water, but soluble in ether :

III I

CH CH-CN

(XIII.) (XIV.)

2-)3-Methylaminoethylbenzaldehyde is, however, a weaker base
than the corresponding alkyloxy-substituted derivatives, for it can
be slowly extracted by solvents from aqtieous solutions after the
addition of sodium carbonate, although much more readily after
the addition of sodium hydroxide, whereas the alkyloxy-substituted
bases can only be extracted after the addition of the latter. Its
salts, the 2-methyl-3 : 4-dihydro?.soqviinolinium salts, differ in an
interesting particular from the alkyloxy-substituted 2-methyI-
3 : 4-dihydro/.soquinolinium salts, for the chloride is colourless, and
the aurichloride golden, whilst in the latter salts the chlorides are
primrose and the aurichlorides brown.

2-Methyl-3 : 4-dihydro/soquinolinium iodide is bright yellow, but
yields a colourless, aqueous solution, behaving in this respect like
many other substituted ammonium iodides (compare Decker, Ber.,
1904, 37, 3938).

It has previously been observed that i\^-benzoyl-l : 2-dihydro-
papaverine does not undergo the same type of change on oxidation
as does xY-benzoyltetrahydropapaverine, and it has now been found
that 1 : 2-dihydropapaverine is similarly stable.

The evidence afforded by the results of the oxidation of sub-
stituted tetrahydroisoquinolines given in this and the two preceding
papers appears to justify the following general conclusions.

1. That substituted l-benzyltetrahydro?.s'oquinolines suffer oxida-
tion and fission simultaneously under the influence of hot dilute
sulphuric acid and manganese dioxide, yielding the aldehyde
corresponding with the substituted benzyl group, and a basic
degradation product.

2. That in the case of substituted l-benzyl-2-alkyltetrahydro^5o-
quinolines (XV), the basic product is a substituted 2-)3-alkylamino-
ethylbenzaldehyde (XVI), which yields salts of the corresponding
2-alkyl-3 : 4-dihydro/«oquinolinium hydroxide (XVII).

3. That in the case of substituted l-benzyl-2-acyltetrahydro?so-
quinolines, and l-benzyltetrahydro/.soquinolines containing a free
imino-group (XVIII), the basic product is a substituted 3 : 4-di-
hydroisoquinoline (XIX) :

PYMAN : ISOQUINOLINE DERIVATIVES. PART III.

1743

CH

N-Alkyl

CH,

+ 0.J _,
— >

CU,
NH-Alkvl "^

CHO

N-Alkyl

— >

(XVI.)
CHo

CH,
NH«

CHO

-H20 _

(XVII.)
CHo

CH

(XVIII.

(XIX.)

4. That substituted l-alkyltetraliydroK^oquinolines do not undergo
this reaction.

In conclusion, the following short account of the physiological
properties of certain woquinoline derivatives described above or
in the preceding papers may be of interest. The physiological
examination of these compounds has been carried out by
Dr. H. H. Dale and Mr. P. P. Laidlaw, of the Wellcome
Physiological Research Laboratories, to whom the author wishes
to express his best thanks.

6 : 7-Dimethoxy-2-methyl-3 : 4-dihydro?".<;oquinolinium chloride (A),
6 : 7-dimethoxy-2-ethyl-3 : 4-dihydro/soquinolinium chloride (B),
2-methyl-3 : 4-dihydroisoquinolinium iodide (C), and 6 : 7-di-
methoxy-2-methyltetrahydro?.soquinoline hydrochloride (D), all have
an action on the isolated uterus similar to that of cotarnine.
6 : 7-Dimethoxy-3 : 4-dihydrowoquinoline hydrochloride (E) has very
little action in this respect.

In their action on the blood-pressure, " B " and " D " are most
like cotarnine, causing a fall, succeeded by a very slight rise.
" A " causes a distinct rise of pressure, due to vaso-constriction.
It is uncertain as yet whether this vaso-constriction is central or
peripheral in origin, but the probability is in favour of the former.
It renders the heart-beat at the same time slower and stronger.
This last action is definitely peripheral, as it can be observed in

1744 PYMAN: ISOQUINOLINE DERIVATIVES. PART III.

the isolated, perfused heart. " E " is more depressant than any
of the others, causing a marked weakening of the heart's action.
" C " is peculiar in the group, in that it causes, in doses of 10 to
20 milligrams, a marked rise of blood-pressure superficially similar
to that produced by adrenine. Whether the action is really of
that kind cannot be decided without further experiment.

The general toxicity of these compounds has been also investi-
gated. " A " and " B " act in this respect much like cotarnine,
but are more toxic, " A " being about one and a-half times and
" B " twice as toxic as cotarnine for the guinea-pig. " D " and
" E " are convulsant poisons, and, of the two, " D " causes the
more marked convulsions, but " E " is lethal in smaller doses.

Experimental.
"N-Ethy^fetrahi/drnjiapaverine, Co2S^'^qO^^.

One hundred grams of papaverine, 50 grams of ethyl iodide, and
250 grams of absolute alcohol were boiled on the water-bath for ten
hours under a reflux condenser. The solvents were then distilled
off, and left a bright yellow, crystalline mass of crude papaverine
ethiodide, which melted at 180 — 200°. Without further purifica-
tion, this was dissolved in 1'7 litres of boiling water, and stirred
for fifteen minutes with 47 grams of freshly precipitated silver
chloride. After filtration, the liquor was concentrated to a thick
syrup, which was then mixed with 400 c.c. of concentrated hydro-
chloric acid and 400 c.c. of alcohol, and digested on the water-bath
with 200 grams of tin for sixteen hours. The liquor was next
decanted from undissolved tin, evaporated to remove the alcohol,
and then diluted with water. This caused the separation of a
putty-like tin salt, which was collected, dissolved in 3 litres of
boiling water, and decomposed by a stream of hydrogen sulphide.
The liquor was then filtered, cooled, and mixed with an excess of
10 per cent, aqueous sodium hydroxide. The base, which first
separated as an oil, readily became crystalline, and was collected
and well washed with cold water; the yield amounted to 66 grams,
that is, 60 per cent, of the theoretical.

J^-Ethyltetrahydro'pa'paverine crystallises from absolute alcohol
in white, fluffy needles, which melt at 89° (corr.). It is insoluble
in water, and somewhat sparingly soluble in cold alcohol :

0- 1582 gave 0-4102 COg and 0- 1 105 HgO. C = 70-7 ; H = 7-8.
01421 „ 4-7 c.c. Ng at 17° and 762 mm. N = 3-9.

C22H29O4N requires C = 711; H = 7-9; N = 3'8 per cent.

The jncrate crystallises from alcohol in yellow, monoclinic prisms

PYMAN : ISOQUINOLINE DERIVATIVES. PART III. 1745

with a macrodome, and melts at 167 — 170° (corr.). It is anhydrous,
and is sparingly soluble in water or cold alcohol :

0-1543 gave 03166 CO.^ and 00778 H,,0. C-56-0; H-5-7.

0-1423 „ 11-0 CO. No at 19° and 770 mm. N = 9-2.
C22H2904N,C6H307N3 requires C=--56-0; H = 5-4; N = 9-3 per cent.

A: b-Dimethoxy-%^-ethtjlaminoethylhenzaldehyde (I, p. 1739).

This base was prepared by the oxidation of iY-ethyltetrahydro-
papaverine. Since the method employed was precisely similar to
that used for the preparation of 4 : 5-dimethoxy-2-i8-methylamino-
ethylbenzaldehyde from laudanosine, a detailed description of it is
unnecessary.

Sixty grams of T-ethyltetrahydropapaverine gave, on oxidation
with 36 grams of pyrolusite, containing 80 per cent, of manganese
dioxide, in dilute sulphuric acid solution, 28 grams of 6 : 7-di-
methoxy-2-ethyl-3 : 4-dihydro/6'oquinolinium chloride, that is, 59 per
cent, of the theoretical.

The base separates as an oil on the addition of 50 per cent,
aqueous sodium hydroxide to a concentrated aqueous solution of
the chloride, but has not been obtained in a crystalline form. It
combines with acids, forming salts by substitution of the isomeric
6 : 7-(Iimethoxy-2-ethj/l-3 : A-dihydroisoquinolinium hydroxide.

The chloride crystallises from a mixture of one part of absolute
alcohol and 9 parts of absolute ethyl acetate in bunches of broad,
yellow, glistening needles, which contain 2 molecules of water of
crystallisation, and melt at 91 — 92° (corr.). After drying at 100°,
this salt decomposes at about 190° (corr.). It is easily soluble in
water or alcohol, giving neutral yellow solutions, which show a
beautiful blue fluorescence when sufliciently diluted :

0-1797, air-dried salt, gave O'SolO COo and 0-1218 HgO. C = 53-3;

H=:7-6.
0-6511, air-dried salt, lost 00812 at 100°. HgO = 12-5.
Ci3Hi802NCl,2H20 requires C = 53-5; 11 = 7-6; HoO^ 12-4 per cent.

0-1590, dried at 100°, gave 0-3557 CO., and 0-1018 HgO. C = 61-0 ;

H = 7-2.
0-1421, dried at 100°, gave 0-0809 AgCl. CI = 14-1.
CisHigOoNCl requires C = 61-0j H = 7-l; CI = 13-9 per cent.

The aurichloride crystallises from absolute alcohol in chestnut-
brown, serrated needles, which melt at 138 — 139° (corr.). It is
anhydrous, and is very sparingly soluble in water or cold alcohol :

0-1865 gave 0-0658 Au. Au = 35-3.

C^aHigOgNCl^Au requires Au = 35-3 per cent.

1746 PYMAN: ISOQUINOLINE DERIVATIVES. PART III.

The jiicrate crystallises from alcohol in hard, yellow, glistening
rods, which melt at 139—140° (corr.).

4 : 5-Dimethoxy-2-)8-ethylaminoethylbenzaldehyde behaves simi-
larly to its methyl homologue ; thus, it is converted into 1-keto-
6 : 7-dimethoxy-2-ethyltetrahydro/soquinoline and 6 : 7-dimethoxy-
2-ethyltetrahydro/;;oquinoline by the action of hot aqueous sodium
hydroxide, and yields bis-(4 : 5-dimethoxy-2-)8-ethylaminoethyi-
benzylidene)acetone when dissolved in dilute aqueous sodium
hydroxide and mixed with acetone.

\-Keto-Q) : l-dimetlioxy-2-etliyUctrahydruisoquinoUne, C13HJ7O3N.

This compound crystallises from a mixture of xylene and light
petroleum in large, colourless, monoclinic plates, which melt at 95°
(corr.). Its solubilities and chemical properties are similar to those
of the methyl homologue :

0-1517 gave 0-3703 CO2 and 00994 H.p. C = 66-5; H = 7-3.

0-1580 „ 8-3 c.c. No at 14° and 752" mm. N = 6-2.

CisHi^OsN requires C = 66-3; H = 7-3; N = 6-0 per cent.

6 : l-Dimethoxy-2-ethyltetrahydruisoquinoline, C13HJ9O0N.

This compound is purified by crystallisation of the hydrochloride,
regeneration from the pure salt, and distillation under diminished
pressure.* It distils at 218°(corr.)/37 mm. as a colourless oil,
which slowly solidifies. On crystallisation from light petroleum,
this base separates in clusters of prismatic needles, which melt at
34 — 35° (corr.). It is readily soluble in cold water, but very
sparingly so in boiling water, and is very easily soluble in all the
usual organic solvents at the ordinary temperature, but sparingly so
in light petroleum at 0° :

0-1546 gave 03979 C0._, and 0-1206 HgO. C = 70-2 ; H = 87.
C13H19O0N requires C = 70-5; H = 8-7 per cent.

The hydrochloride crystallises from moist ethyl acetate in short,
white needles, which are anhydrous, and melt at 237 — 239° (corr.).
It is readily soluble in water or alcohol :

0-1474 gave 0-3260 COo and 0-1048 HoO. C = 60-3; H = 8-0.

0-1485 „ 00819 AgCl. CI = 137."

Ci3Hj902N,HCl requires C = 60-5; H = 7-8; CI = 138 per cent.

* 6 : 7-Dimethoxy-2-mcthyltetrahyclroisoqiiinoUne distils at 210'(corr.)/40 mm. ;
this base is readily oxidised to 4 : 5-dimethoxy-2-)3-methylarninoetliylbenzald«hyde
by cold dilute chromic acid.

PYMAN: ISOQUINOLINE DERIVATIVES. PART III. 1747

Bis-(i : 5-flimef/iojj/-2-^-('thi/hi/ninof(/i//lh('n:i/lidene)acetone,

The base was obtained as a colourless oil, which did not crystallise.
The ilUiijdroclilorich separates as a white, crystalline powder when
a solution of the base in acetone is neutralised with concentrated
hydrochloric acid, and has been obtained in two hydrated forms
with 1 and 2\ molecular proportions of water of crystallisation.
It readily yields 6 : 7-dimethoxy-2-ethyl-3 : 4-dihydro«soquinolinium
chloride when heated with water, but on dissolving it quickly in
boiling water and cooling immediately, a small proportion separates
again as a crystalline powder, which decomposes, becoming orange
in colour at about 197° (corr.). It is very sparingly soluble in
cold water or alcohol :

0-5368, air-dried, lost 0-0149 at 100°. H.,0 = 2-8.

0-2377 „ ,. 0-0183 „ 100°. H._,0 = 7-7.

C.,9H4oO.:^No,2HCl,H.O requires HoO = 3-l per cent.
C.,9H4o05N._,,2HCl,2AHoO „ HoO = 7-3 „

0-1612" dried at 100°, gave"o-3593 CO. and 01091 HoO. 0 = 608;
H = 7-6.

0-3503, dried at 100°, gave 0-1731 AgCl. CI = 12-2.

Co9H4oOoN.2,2HCl requires C = 61-l; H = 7-4; CI = 12-4 per cent.

The following propyl derivatives were prepared in the same
manner as the corresponding ethyl homologues.

l^-Propyltetrahydropapaverine, C03H31O4N.

This base was obtained in an amorphous form by the reduction
of papaverine propochloride.

The pic rate crystallises from absolute alcohol in large, irregular,
yellow prisms, which melt at 122 — 125° (corr.). It is anhydrous,
and is sparingly soluble in water or cold alcohol :

0-1509 gave 03117 CO^ and 00751 H.O. 0 = 563; H = 5-6.
CgaHgiO^NjOcHgOjNg requires 0 = 566; H = 5-6 per cent.

4: 'o-Dimethoocy-2-^-propylaminoethylhenzaldehyde (II, p. 1739).

This base was prepared by the oxidation of i\*-propyltetrahydro-
papaverine; it separates as an oil on the addition of 50 per cent,
aqueous sodium hydroxide to a concentrated solution of the
chloride, but has not been obtained in a crystalline form. It
combines with acids, forming salts by substitution of the
corresponding 6 : l-dimethoxy-2-prupyl-Z : A-di/tydroisoquinolinium
hydrojcide.

1748 pyman: isoquinoline derivatives, part hi.

The chlorulc crystallises from a mixture of 1 part of absolute
alcohol and 9 parts of ethyl acetate in clusters of small, primrose
needles, which melt at 78 — 79° (corr.). It is easily soluble in
water, giving a yellow solution, which shows a blue fluorescence
when diluted. This salt contains 2 molecules of water of crystal-
lisation, and is gradually converted into an amorphous, deliquescent
gum on partial dehydration either in a vacuum over sulphuric acid
or on heating :

01568, air-dried salt, gave 0-3122 COo and 0-1099 HgO. C = 54-3;
H = 7-9.

0-1768, air-dried salt, gave 0-0826 AgCl. CI = 11-6.
C,4HooOoNCl,2HoO requires C = 54-9j H = 7-9; CI = 11-6 per cent.

The jjicrate crystallises from alcohol in beautiful, long, deep yellow
needles, which begin to sinter at 146° and melt at 148 — 149° (corr.).
This salt is anhydrous, and is very sparingly soluble in water and
sparingly so in cold alcohol :

0-1543 gave 0-2916 COo and 0-0662 HoO. C = 51-5; H = 4-8.
C20H22O9N4 requires C = 5r9j H = 4-8 per cent.

1-Keto-G : l-dimethoxy-2-'pro'pyltetrahydroisoquinoline, Cj^H^gOgN.

This compound crystallises from a mixture of benzene and light
petroleum in large, colourless, oblong, monoclinic plates, which
begin to soften at 75°, and melt at 77° (corr.). It is easily soluble
in water and the usual organic solvents, with Ihe exception of light
petroleum :

0-1515 gave 0-3727 COo and 0-1042 HoO. C = 671 ; H = 7-7.
C14H19O3N requires C = 67-4; H = 7-7 per cent.

6 : l-TJimethoxy-2-'pro'pyltetrah.ydro\^oquinoline, CJ4H21O2N.

This base was obtained as a pale yellow oil which did not
crystallise on keeping.

The hydrochloridt crystallises from aqueous acetone in microscopic,
fluffy needles, which melt to a yellow liquid at 224° (corr.). This
salt is easily soluble in water, but sparingly so in cold alcohol. It
contains half a molecular proportion of water of crystallisation,
which is not entirely lost at 150°:

0-1534, air-dried salt, gave 0-3379 COo and 0-1129 HoO. C = 60-1 ;
H = 8-2.

0-1805, air-dried salt, gave 0-09^0 AgCl. Cl = 12-9.
Ci4H2i02N,HCl,iIl20 requires 0 = 598; H = 8-3j CI = 12-6 per cent.

I!

PYMAN: ISOQUINOLINE DERIVATIVES. PART III. 1749

Oxidation of \-Benzyl-2-methyltetrahydroisoquinoline.

Eighteen grams of l-benzyl-2-methyltetrahydro/soquinoIine were
dissolved in a mixture of 35 grams of concentrated sulphuric acid
and 250 c.c. of water, and well stirred with 16'6 grams of pyrolusite,
containing 80 per cent, of manganese dioxide, for three-quarters of
an hour on a steam-bath. The mixture was then distilled in a
current of steam, and the resulting distillate extracted with ether,
which removed 33 grams of benzaldehyde ; this was recognised
by its characteristic odour, and by the formation of the phenyl-
hydrazone, which melted at 158 — 160° (corr.). The residual liquor
from the steam distillation was filtered from a quantity — perhaps
2 grams — of resinous matter, extracted with ether, which removed
I'O gram of yellow oil, containing some benzaldehyde, rendered
alkaline with sodium carbonate, and again extracted with ether,
which removed a crystalline basic compound rather slowly. Sodium
hydroxide solution was then added, and the extraction continued,
when the same crystalline base was readily extracted. The ethereal
residues from both extractions were evaporated to low bulk, and
then allowed to evaporate to dryness spontaneously, when in each
case the residue consisted of colourless prisms covered with a brown
oil. On stirring the residues with acetone and filtering, the crystals
of 2-j8-methylaminoethylbenzaldehyde were obtained in an almost
pure condition; the yield amounted to 56 grams, that is, 45 per
cent, of the theoretical.

No further quantity of crystalline material could be obtained
from the acetone liquors, either in the form of the base or that
of a salt.

2-$-Methylaminoethylhenzalciehyde (IX, p. 1741).

This base crystallises from ether, acetone, or benzene in beautiful,
colourless prisms, which melt at 110 — ^111° (corr.). It is very
sparingly soluble in water or light petroleum, sparingly so in cold
acetone, fairly easily so in ether or benzene, and readily so in
alcohol, ethyl acetat<3, or chloroform :

0-1508 gave 0-4076 COo and 0-1082 HoO. C = 73-7; H = 8-0.

0-1506 „ 11-1 c.c. No at 24° and 756" mm. N = 8-4.

C10H13ON requires 0 = 736; H = 8-l; N = 8-6 per cent.

The base is readily soluble in dilute acids, forming salts derived by
substitution from the isomeric 2-methyl-Z: i-di/iydroisoquinoUnium
hydroxide.

The chloride forms colourless crystals, wliich are very deliquescent,
and are readily soluble in water or alcohol, but insoluble in acetone.

VOL. xcv. 5 z

1750 PYMAN: ISOQUINOLINE DERIVATIVES. PART III.

The iodide crystallises from absolute alcohol in long, bright yellow
needles, which become orange, and begin to soften at about 115°,
and melt at 125 — 128° (corr.) to a red liquid. This salt is
anhydrous, and is easily soluble in water, giving a colourless,
neutral solution, but rather sparingly so in alcohol :

0-1527 gave 0-2459 CO. and 0-0605 HgO. C = 43-9; H = 4-4.
C10H12NI requires 0 = 439; H = 4-4 per cent.

The aurichloride crystallises from absolute alcohol in bright
golden, feathery needles, which melt at 145° (corr.). It is very
sparingly soluble in water or cold alcohol, and is anhydrous :

0-1822 gave 0*1672 OOg and 0-0435 HgO. 0 = 25-0; H = 2-7.

0-2180 „ 0-0888 Au. Au = 40-7.
O10HJ2NOI4AU requires 0 = 24-7; H = 2-5; Au = 40-6 per cent.

The picrate crystallises from alcohol in fine, silky, yellow needles,
which melt at 145° (corr.), after previous sintering. It is sparingly
soluble in water or cold alcohol :

0-1383 gave 0-2588 OOg and 0-0470 HgO. 0 = 51-0 ; H = 3-8.
O16H14O7N4 requires 0 = 51-3; H = 3-8 per cent.

\-Gyano-2-inethyltetrahydroi'&oquinoline (XIV, p. 1742).

This compound separates on the addition of potassium cyanide
to an aqueous solution of 2-methyl-3 : 4-dihydrozsoquinolinium iodide
as an amorphous, white precipitate, which quickly becomes crystal-
line. After crystallisation from ether, it forms long, flat needles,
which melt at 77 — 78° (corr.). This compound is almost insoluble
in water, but readily soluble in alcohol or ether :

0-1500 gave 0-4197 OOg and 0-0942 HoO. 0 = 76-3 ; H = 7-0.
OjiH^gNg requires 0 = 767; H = 7-0 per cent.

Bis-{%^-methylaminoethylhtnzylidene)acetone (XI or XII, p. 1741).

This base separates as a colourless oil on the addition of acetone
and aqueous sodium hydroxide to an aqueous solution of 2-methyl-
3 : 4-dihydro/5oquinolinium chloride. It becomes crystalline on
keeping, and, after recrystallisation from dry ether, forms colourless,
silky needles, which melt at 105 — 106° (corr.), and are anhydrous.
This base is insoluble in water, easily soluble in alcohol, and
moderately easily so in ether :

0-1440 gave 0-4178 COg and 01089 H^G. 0 = 79-1; H = 8-5.
O23H2SON2 requires 0 = 79-2; H = 8-l per cent.

The dihydriodide separates in clusters of white, feathery needles
on neutralising an acetone solution of the base with hydriodic acid.

pyman: isoqui-Voline derivatives, part III. 1751

This salt decomposes, and becomes orange at about 180° (corr.).
It is anhydrous, and is very sparingly soluble in water or alcohol :
0-1571 gave 0-2619 COo and 0-0724 II^O. C = 45-5; H = 5-2.
Co3H280N2,2HI requires C = 45-7; H = 5-0 per cent.

Oxidation of l-BenzyUbydrocotarnine.

Ten grams of 1-benzylhydrocotarnine, 20 grams of sulphuric acid,
and 150 c.c. of water were heated for half an hour on the water-bath
with 7 grams of pyrolusite, containing 80 per cent, of manganese
dioxide; the reaction product was worked up in the usual manner,
and gave 2-7 grams of cotarnine, that is, 35 per cent, of the
theoretical.

Oxidation of l-Profylhydrocotarnine.

Seven grams of 1-propylhydrocotarnine, 20 grams of sulphuric
acid, and 150 c.c. of water were heated for one hour on the water-
bath with 5-8 grams of pyrolusite, containing 80 per cent, of
manganese dioxide. The product was extracted with ether, which
removed 0-1 gram of brown, resinous matter, and mixed with solid
potassium iodide, which caused the precipitation of 4-5 grams of
crude 1-propylhydrocotarnine hydriodide; this was removed by
filtration, and the liquor rendered alkaline by sodium carbonate,
when a quantity of resinous matter separated, together with the
manganese carbonate. After filtration, the liquor was extracted
with ether, which removed 0-25 gram of a brown oil, from which
a further small quantity of crystalline 1-propylhydrocotarnine
hydriodide was obtained. The final mother liquor was mixed with
aqueous sodium hydroxide and again extracted with ether, which
removed only 0*25 gram of a brown gum, from which no crystalline
material could be obtained.

It is, therefore, clear that under these conditions a large pro-
portion of the 1-propylhydrocotarnine escapes oxidation, and that
no cotarnine is formed.

Oxidation of \-Ethylhydrocotarnine.

Seventeen grams of 1-ethylhydrocotarnine were heated for three-
quarters of an hour on the water-bath with 50 grams of sulphuric
acid, 400 c.c. of water, and 15 grams of pyrolusite, containing 80 per
cent, of manganese dioxide; more than 10 grams of unchanged
1-ethylhydrocotarnine were recovered from ^he product of the
reaction, but no cotarnine was obtained.

5 z 2

1752 MOIR : A METHOD OF HARMONISING

Oxidation of Tetrahydropapaverine.

Thirty grams of tetrahydropapaverine were oxidised with 60 grams
of sulphuric acid, 500 c.c. of water, and 20 grams of pyrolusite,
containing 80 per cent, of manganese dioxide. The product was
worked up in the same way as that from i\^-benzoyltetrahydro-
papaverine, and gave 13 grams of a brown liquid base, liberated by
sodium carbonate. On dissolving this in acetone and neutralising
with hydrochloric acid, 8 grams of 6 : 7-dimethoxy-3 : '4-dihydro-
isoquinoline hydrochloride were obtained.

0 xidation of 1 : 2-Dihydro'pa'paverine.

Eight grams of 1 : 2-dihydropapaverine, 16 grams of sulphuric
acid, 120 c.c. of water, and 5 grams of pyrolusite were heated for
three-quarters of an hour on the water-bath; the liquor deposited,
on cooling, a quantity of crystalline 1 : 2-dihydropapaverine
hydrogen sulphate, which yielded 56 grams of 1 : 2-dihydro-
papaverine. On working up the mother liquor in the usual manner,
further small quantities of the same base were obtained, but no
crystalline degradation product could be isolated.

The Wellcome Chemical Works,
Daktford, Kent.

CXCIL — A Method of Harmonising the Atomic Weights.

By James Moir, D.Sc, M.A.

The idea now to be presented occurred to the author eighteen months
ago, but as it gave an incorrect result when applied to carbon as 12*00
(0= 16), it was not pursued farther. The recent determinations, how-
ever, of Dr. A. Scott give a value in agreement with the theory, and
the author ventures therefore to put it forward in a new form as
modified by the appearance of A. EgerLon's paper (this vol., 238).

Briefly, the author assumes the cause of valency, at all events the
fundamental valency of each element, to be the presence, in varying
numbers, of a sub-element of atomic weight ^\^ (probably eight or
nine electrons *), practically in the same way as Sir W. Ramsay assumes
the electron to behave. If this be denoted by /x, then the univalent
elements contain 1/i,, the bivalent 2/x, the tervalent 3^ and so on. In
addition, the author conceives the main bulk of the mass of the
elements to be due to polymerisation of an entity consisting of the

hydrogen atorr, less the aggregation /x. Denoting this by H, we have
* Fifteen, aaording to the recent redetermination of the electron as 0 00060.

THE ATOMIC WEIGHTS. 1755

for example: ll = K + fi; Li = 7H + /i; C=12H + V; 0=lGIi + 2/x;

Ne = 20H; Na=:23H+/i; Ag=108H + /Li; Cs=133H+/x. The
elements which do not agree with this system are probably not direct

polymerides of H ; but their atomic weights can practically all be
expressed in the above way, by having recourse to a fraction of one
decimal place exactly. This assumes the existence of another sub-
element of exactly one-tenth the weight of hydrogen. Thus, for

example: G\ = d'lK + 2fj. ; Mg = 24-3H + 2/x ; Si = 28-3H + V ;

Cr = 52-lH-l-6^; CI = 35-5H -f /t ; Ba = 137-5 H -f 2/x, and so on.
Although this system savours of manipulation, it will be found that
the results calculated by it agree in a most remarkable way with the
experimental values.

It should be noted by the way that most of the agreement found by
Egerton in his calculations is due to mathematical necessity, for wlien
a number, say iV, is divided b}' r007'S, the true result is xV(l - 0 0078 -f-
0-OOOOG), that is, the error in assuming it to be ^V- 0-0078i\'' does not
affect the third place of decimals unless iV is large. The value«! in
column V (H=l) on p. 239 of his paper have been calculated from
iV/ 1*0078, except, curiously enough, in the case of oxygen, where
iV(l - 0'0078) has been used; this value should therefore (to be
consistent) be 15"8763.

The following table exhibits the author's results ; and column TY,

Table

I. II. III. IV. V.

Natural Ibimula Calculated

(H taken Forniula atomic weight

Symbol. equal to 1). x 112. 0 = 16-000 Error.

H 1 + M 11:3 1-0078 nil

He 4 448 3-9955 ?

Li 7 -f M 785 70011 ?

Gl 9-l+2fi 1021 9106 ?

B 11 +3m 1235 11-014 0 01

C 12 +4ix 1348 120-22 nil

N 14 +3^ 1571 14011 ?

0 16 +2n 1794 16 000 nil

F 19 + M 2129 18-988 0-01

Ne 20 2240 19-978 0-02

Na 23 + M 2577 22984 0-016

Mg 24-3-h2/t 2724 24-295 0-025

Al 27-1-1-3^ 3038 27-095 1

Si 28-3 + 4M 3174 28-308 ?

P 31 -t-3M 3475 30-993 ?

S 'S21 + 2/J. 35S«7 32-080 Q-Ol

CI 35-5+ fi 3977 35-4695 ?

A 40 4480 39-957 0 04

K 39-1+ M 4380 39 064 0-03

Ca 40-1-1-2/* 4493 40-072 0-02

1754 A METHOD OF HARMONISING THE ATOMIC WEIGHTS.

Table (continued).

I. II. III. IV. V.

Natural formula Calculated

(li taken Formula atomic weight

Symbol. equal to 1). x 112. 0 = 16-000 Error.

Sc 44-]+3/i 4942 4408 0-02

Ti 48-1 +4m 5391 48-08 002

Y 51-24 5ju 5739 51-19 ?

Cr 52-1 + 6m 5841 52-094 ?

Mil 55 +2u 6162 54-956 0-026

Fe 55-9 + 2^ 6263 55-858 nil

Ni 58-7 + 2^ 6576 58-65 0 03

Co 59 +2m 6610 58-95 ?

Cu 63-6 + 2M 7125 63546 0-02

Zn 65-4 + 2M 7327 65-347 0-02

Ga 70 +3m 7843 69-95 ?

Ge 72-5 + 4M 8124 7246 ?

As 75 +2^ 8403 74-95 ?

Se 79-3 + 2/i 8884 79-23 ?

Br 80 + fi 8961 79-920 nil

Kr 83 9296 82-91 ?

Rb 85-54- M 9577 85-415 0-035

Sr 877 + 2^ 9824 87-617 nil

Y 89 +3/i 9971 88-93 0-07?

Zr 90-6 + 4ju 10151 90-53 0-07?

Cb 93-6 + 5^ 10488 93-54 0-04

Mo 96 +6fi 10758 95-95 0-05

Ru 101-8 + 8^ 11410 101-76 ?

Rh 103 +8m 11544 102-96 ?

Pd 106-8 + 2/i 11964 10670 nil

Ag 108 + fj. 12097 107-889 nil

Cd 112-5 + 2M 12602 112-40 nil

In 115 +3ac 12883 114-90 ?

Sn 119 +4ix 13332 118-905 0-095

Sb 120-3 + 3^ 13477 12020 nil

Te 127-6 + 2/11 14293 127-48 ?

I 127 + M 14225 126-87 0-05

X. 130 14560 129-86 ?

G 133 + n 14897 132-86 ?

Ba 137-5 + 2^ 15402 137-366 nil

La 139 +3fi 15571 138-87 0-13?

Ce 140-3 + 3^ 15717 140-175 0-07

Pr .. 140-7 + 3M 15762 140-58 ?

Nd 144-5 + 3^ 16187 144-37 ?

Sa 150-5 + 3jii 16859 150-36

Eu 152 +3m 17027 151-86 ?

Yb 172 +3/i 19267 171-84 ?

Ta 181 +5ii 20277 180-845 0-15

W 184 +6^ 20614 183850 015

Os 191 +8m 21400 190-86 ?

Ir 193-3 + 8/i 21658 193-16 ?

Ft 195-2 + 4^ 21866 195-01 nil

Au 197-4 + .3/i 22112 197-21 nil

Hg 200-2 + 2/i 22424 200-00 nil

Tl 204-2+ fi 22871 203-99 nil

Pb 207-3 + 2/u 23220 207-10 nil

Bi 208-3 + 3At 23333 208-11 nil

Ra 226 +-2fj. 2.'^314 225-77 ?

Th 233 +4fi 26100 23278 03

U 239 +6/t 26774 238-80 OS

CONSTITUTION OF POLYNITROPHENOLS. 1755

wherein the atomic weights are reduced to 0 = 16 from column II
where O=16'018, shows a very close approximation to the accepted
atomic weights.

The system therefore does not break down, as does Egerton's, in the
case of any of the well-ascertained atomic weights; and the author
hopes that it will evoke interest, even if only as a curiosity of
coincidences.

Mines Dei'Artment,
johannesbuug.

CXCIII. — The Constitution of Polynitrophenols hi

Alkaline Solution.

By Bertram Hajward Buttle and John Theodore Hewitt.

The suggestion thrown out years ago by Armstrong that the colour
of the salts of the nitrophenols can be best explained by assigning
to them a quinonoid constitution has received considerable support
during the past few years, and probably the number of chemists who
disagree with the view that ortho- and para-nitrophenols and their
metallic salts have radically different constitutions is very limited,
the markedly different absorption spectra of these compounds in
neutral (or acfd) and alkaline solutions (Baly, Edwards, and
Stewart, Trans., 1906, 89, 519, 521), and the isolation of aci-esicxs
by Hantzsch and Gorke {Ber., 1906, 39, 1073; compare Kauffmann,
Ber., 1907, 40, 843, 4547, and Hantzsch, ihid., 1906, 39, 1959,
and 1907, 40, 1556), being scarcely capable of any other inter-
pretation.

To the authors of the present communication the question of
the absorption spectra of these compounds has been of considerable
interest as giving an example of the dependence of oscillation
frequency on the length of chain of conjugate linkings, and, further,
that one has a chance of deciding, at any rate in particular
instances, whether, when salt formation is accompanied by quinonoid
rearrangement, and the latter may be either of ortho- or of para-
type, which of the two possible configurations is preferred.

Respecting the first of these questions, the curves of Baly,
Edwards, and Stewart {loc. cif.) seem to give a very decided
answer, for the oscillation frequency of the para-compound is
greater than that of the ortho-isomeride, even in neutral solution,
whilst, on comparing the alkaline sokitions, one sees immediately
that, whereas the head of the band in the case of sodium p-nitro-

\

1756

BUTTLE AND HEWITT : THE CONSTITUTION OF

phenoxide corresponds with an oscillation frequency of about 2450,
that of the corresponding ortho-salt is about 2300. Inspection of
the quinonoid formulas of the isomeric sodium salts shows that
whilst both possess an equal number of double Unkings, a longer
conjugate chain exists in the case of the ortho- than of the para-
compound. It will be noted that our results for polynitrophenols
fully correspond.

The second point, preference for ortho- or para-quinonoid con-
figuration, is of some interest from several points of view. Thus,

•^

Fig. 1.
Oscillation frequencies.
00 22 24 26 28 3000 32 34 36 38 4000 42 44

0

8

6

4

' • \ • ^•

2
0
8
6
4

2
•0

^

2 : &-Dinitrophenol.

Sodium 2 : 6-dinitrophenoxide.

2 : i.-Dinitrophenol.

Sodium 2 : i-dinitrophenoxide.

2 : i-Dinitrophenelole.

many compounds, which until a few years ago were generally
regarded as possessing para-quinonoid structure, have been formu-
lated by Kehrmann with an ortho-quinonoid constitution (Ber., 1899,
32, 927; 1905, 38, 2577; 1907, 40, 1960, and many other papers),
despite the excellent arguments adduced by Hantzsch to the con-
trary, and evidence which has been obtained from the examination
of acridine derivatives (Hewitt and Fox, Trans., 1904, 85, 529;
1905, 87, 1058). The study of the absorption spectra of neutral
and alkaline solutions of 2 : 4-dinitrophenol seemed likely to give a

POLYNITROPHENOI.S IN ALKALINE SOLUTION. 1757

clue to the relative probability of wliich structure would be produced
when both were possible.

As will be seen by reference to Fig. 1, the head of the band in
the case of an alkaline solution of 2 : 6-dinitroplienol is near to
oscillation frequency 2300, very near, in fact, to the position found
by Baly and his co-workers for o-nitrophenol in alkaline solution,
and although the head of the band is broader in the case of the
dinitrophenol, a comparison of the two frequency curves shows their
great similarity. The general resemblance holds when one compares
the curves for a neutral solution of o-nitrophenol with that of the
2 : 6-dinitrophenol to which dilute hydrochloric acid has been
added.

A marked difference exists, however, between the absorption
spectra of the alkaline solutions of 2 : 4- and 2 : 6-dinitrophenols.
An acid solution of the 2 : 4-dinitrophenol shows a broad band with
head at an oscillation frequency of nearly 3400, and comparison
with 2 : 4-dinitrophenetole exhibits sufficient similarity to lead to
the conclusion that the free compound exists in acid solution as a
true dinitrophenol. The alkaline solution of the 2 : 4-dinitrophenol
has an absorption spectrum which, although differing markedly from
that of the alkaline 2>nitrophenol, nevertheless resembles this to a
greater degree than the alkaline solution of the o-nitrophenol.
Thus, whilst o-nitrophenol and 2 : 6-dinitrophenol in alkaline solu-
tions both give absorption bands having heads at an oscillation
frequency of about 2300, the head of the corresponding band in
the case of alkaline p-nitrophenol is at 2450, whilst with 2 : 4-dinitro-
phenol the band is much broader and less persistent, the head
corresponding to an oscillation frequency of somewhere about 2700.
Thus, of the two possible quinonoid structures for alkali salts of
2 : 4-dinitrophenol,

O O

II II

\/ \^

NO2M ^^2

(I.) (11-)

the para-quinonoid (I) is to be preferred.

The specimens of 2 : 4- and 2 : 6-dinitrophenols employed in thia
work were obtained from Schuchardt, recrystallised and checked as
to purity by means of their melting points. The 2 : 4-dinitro-
phenetole was a specimen prepared some years ago in a high state
of purity by one of us ; for this work it was again recrystallised,
and showed a melting point of 86°. The aqueous alkaline solutions,
as spectroscopically examined, were i\^/ 10,000 with regard to the

1758

BUTTLE AND HEWITT: THE CONSTITUTION OF

dinitrophenol, the alkali, -whicli was present in ten times the
equivalent amount, being iV/lOOO. The acid solutions contained
100 molecules of hydrochloric acid per molecule of dinitrophenol.
The object of this considerable excess of hydrochloric acid was, of
course, to prevent ionisation, since the ions would doubtless be
produced from the aci-forms of the phenolic compounds. Bader
determined the dissociation constants of several substituted phenols
in 1890 (Zeitsch. phj/sikal. Che}?!-., 6, 289), and obtained values of
K for 2 : 4- and 2 : 6-dinitrophenols of 0-0080 and 00174 respec-

"^

Fig. 2.
Oscillation frequencies.
2000 22 24 26 28 3000 32 34 36 38 4000 42 44

Picric acid.

Trinitroanisole.

tively; it is evident, therefore, that under the conditions employed
ionisation of the free dinitrophenols may be disregarded.

For purposes of comparison, acid and alkaline solutions of picric
acid were also examined, the molecular proportions of trinitro-
phenol, alkali, and acid being the same as in the preceding cases.
In these circumstances, practically no difference was found in the
absorption spectra, a result which might be expected, considering
the strength of picric acid and its almost complete dissociation at
even quite moderate dilutions. The curve reproduced (continuous
line, Fig. 2) is that obtained from measurements of an acid solution.
If one could obtain a solution of the true trinitrophenol (in a

POLYNITROPHENOLS IN ALKALINE SOLUTION.

1759

solvent transparent to the ultraviolet rays), it would doubtless
give an entirely different absorption spectrum, judging from
the results obtained with an alcoholic solution of trinitroanisole,*
and the fact that solutions of picric acid vary in colour
according to the ionising power of the solvent. Thus Walden
(Ber., 1899, 32, 2864) describes the solution in liquid sulphur
dioxide as being colourless, although those of phenol and quinol
are distinctly yellow. Marckwald (Bcr., 1900, 33, 1128) also draws
attention to the fact that ordinary yellow picric acid gives with
light petroleum a colourless solution, which, however, immediately
communicates a yellow colour to water when shaken with it.

The close similarity between the absorptions exhibited by alkaline
solutions of 2 : 4-dinitrophenol and of picric acid (head about 2800)
point to the ions of both these substances having similar structures
when they are to be considered as nitro-derivatives of aci-p-nitro-
phenol ; that is, having para- rather than ortho-quinonoid structure.

The strengths of the nitrated nitrophenols as acids is of some
interest in connexion with the identification of the salts of 2 : 4-di-
nitrophenol and of picric acid as 2^-quinonoid compounds. The
dissociation constants, as found by Bader (loc. cit.) for o- and
p-nitrophenols and their higher nitrated derivatives, are as follows.

Derivatives of o-Nitrophenol.

2-Nitrophenol 0-000043

2:3-Dinitroj)henol 0-0012

2:5-Dinitrophenol 0-0007

2:6-Dinitrophenol 0 0174

Derivatives of jj-Nitrophenol.

4-Nitroplienol 0-000012

2 :4-Dinitro phenol 0 0080

3:4-Dinitropheiiol 0-0004

2:4 :6-Triintrophenol Strong acid.

In each case it will be noted that a nitrophenol is strengthened
as an acid by the introduction of another nitro-group, the effect
produced being .greatest when the second nitro-group enters the
meta-position with respect to the nitro-group already present.

There is possibly some connexion between this influence and the
weakening of the attachment of nitro-groups to aromatic nuclei
produced by the presence of other nitro-groups in a meta-position.
On this mobility depends the oxazine synthesis of Turpin (Trans.,
1891, 59, 722), the production of dinitroanisole from 1:3: 5-tri-
nitrobenzene (Lobry de Bruyn, Rec. trav. chim., 1890, 9, 209),
and several azine syntheses (see Kchrmann, Ber., 1899, 32, 2601),
whilst it is noticeable that the trinitroacetylaminophenol described
by Meldola (Trans., 1906, 89, 1935) and subsequently employed
by Meldola and Hay in many syntheses (Trans., 1908, 93, 1659;
1909, 95, 1033) has one of its nitro-groups easily removable, the

Prepared from anisole by extreme nitration, and crystallised from alcohol ;
m. p. 68\ Found N = 17'5 ; C-HgO^Nj requires N = 17-3 per cent.

1760 KNOX : THE SOLUBILITY OF BISMUTH TRISULPHIDE

other two nitro-groups being oriented ortho- and meta- to the
group so readily eliminated as nitrous acid.

In conclusion, we wish to express our indebtedness to the
Government Grant Committee for a grant by which the greater
part of the expense of this investigation has been defrayed.

East London College.

CXCIV. — The Solubility of Bismuth Trisulphide in
Alkali Sulphides and of Bismuth Trioxide in
Alkali Hydroxides.

By Joseph Knox (Carnegie Research Fellow of Aberdeen
University).

Stillman (/. Amer. Chem. Soc, 1896, 18, 683) states that bismuth
sulphide is soluble to a considerable extent in sodium sulphide,
whilst Stone (ibid., 1091), who confirmed this result, found that
if the bismuth was first precipitated as sulphide from an acid
solution, and then treated with alkali sulphide, little, if any,
dissolved. Stillman precipitated a solution of bismuth nitrate with
excess of sodium sulphide, warmed to a temperature near the
boiling point for twenty minutes, filtered, and determined the
bismuth in the filtrate. He gives, however, only one quantitative
experiment, in which, moreover, the strength of the sodium sulphide
employed is uncertain. Stone precipitated bismuth sulphide from
a dilute acid solution of the chloride, filtered, and heated the pre-
cipitate with a large excess of potassium sulphide or of ammonium
sulphide for half an hour. The undissolved sulphide was collected,
redissolved, and the bismuth determined as the oxide. In both
cases the bismuth trioxide found agreed with the amount of bismuth
originally taken as chloride. Stone therefore concluded that
bismuth sulphide, precipitated from acid solution, is not dissolved
by subsequent treatment with alkali sulphides.

Neither author gives the method of preparation or the com-
position of the alkali sulphides employed. Since the term, " alkali
sulphide solution," is applied in analytical chemistry to the solutions
obtained by saturating the hydroxides with hydrogen sulphide to
a greater or less extent, that is, to solutions of the alkali hydro-
sulphides or of the hydrosulphides and hydroxides in varying
proportions, it is possible that such solutions were used by Stone,

AND OF BISMUTH TRIOXIDE. 1761

instead of those containing the dissolved substance in the stoicheio-
metric proportions represented by the formulas Na^S, KoS, etc. This
would explain the discrepancy between the results of Stone and
those of the present investigation.

So far as the author is aware, no further work has been done
on the solubility of bismuth sulphide in alkali sulphides. Owing to
the important bearing of the subject on analytical chemisti'y, and
to its interest from the theoretical point of view, the present
investigation was undertaken in order to ascertain the nature of the
reaction between bismuth sulphide and alkali sulphides, and the
relation between solubility and concentration.

From the position of bismuth in the periodic system
as the highest member of the fifth group, it might be
expected that bismuth sulphide would, like the corresponding
arsenic and antimony compounds, form complex anions with the
sulphur ions of alkali sulphide solutions, although to a much
smaller extent, on account of its greater electro-affinity compared
with these elements (Abegg and Bodlander, Zeitsch. anorg. Chem.,
1899, 20, 453; Abegg, ibid., 1904, 39, 330). Further, it is almost
certain that the behaviour of bismuth sulphide towards solutions
of sodium and potassium sulphides will be practically the same,
owing to the similarity in constitution of the two solutions.

The bismuth sulphide used in the following solubility deter-
minations was mainly " Kahlbaum's precipitated," which was freed
from admixed sulphur by extraction with carbon disulphide and
dried at 100 — 110°. It contained traces of oxychloride, which,
however, in presence of the large excess of alkali sulphide used,
have probably no effect on the solubility determination. In several
experiments the bismuth sulphide used was prepared by pre-
cipitating a dilute solution of bismuth chloride, acidified with hydro-
chloric acid, with hydrogen sulphide, washing the precipitate, and
drying at 100 — 110°. The sulphide so prepared gave the same
solubility as Kahlbaum's. The sodium sulphide solutions were
prepared by saturating a measured volume of standard sodium
hydroxide, free from carbonate, with hydrogen sulphide in a
graduated flask, expelling the excess of hydrogen sulphide by a
current of hydrogen, adding a volume of sodium hydroxide equal
to that originally used, and diluting to the mark with air-free
distilled water. The potassium sulphide solutions were prepared
similarly. The solubility in each strength of alkali sulphide was
determined several times, and the alkali sulphide used in each
determination was freshly prepared. This procedure eliminates, as
far as possible, any error due to slight divergences in the com-
position of the solution from the theoretical, caused by the

1762 KNOX: THE SOLUBILITY OF BISMUTH TRISULPHIDE

impossibility of stopping the liydrogen current used to expel the
excess of hydrogen sulphide at the exact point. These divergences
will, however, always be small, since the concentration of undis-
sociated hydrogen suljDhide in alkali sulphide solutions, and hence
the partial pressure of hydrogen sulphide over them is exceedingly
minute (Knox, Trans. Faraday Soc, 1908, 4, 29). All operations
were performed, as far as possible, in an atmosphere of hydrogen,
so as to avoid oxidation of the solutions by atmospheric oxygen.

The solubility determinations were carried out as follows. The
bismuth sulphide was shaken with the alkali sulphide solutions in
a thermostat at 25° for about three days. In most cases experi-
ments were also carried out in which the shaking was continued
for a much longer period, in order to ensure that the equilibrium
had been attained. In most cases, too, the equilibrium was attained
from both sides. On the one hand, the sulphide solutions were
shaken at 25° with bismuth sulphide until saturation occurred, and,
on the other, the sulphide solutions were first saturated with
bismuth sulphide at about 80°, and then shaken in the thermostat
at 25° until equilibrium for this temperature was reached. The
equilibrium attained under these different conditions was always
the same. For the analyses, the bottles were hung in the thermostat
until the solid had completely settled; 100 c.c. of the clear solution
were then transferred to a beaker and carefully acidified with a
slight excess of hydrochloric acid. This precipitated most of the
bismuth sulphide, although the supernatant liquid remained brown,
apparently owing to some of the sulphide remaining in colloidal
solution, since the liquid cleared on standing. Hydrogen sulphide
was passed in to complete the precipitation, and the precipitate
was collected in a Gooch's crucible, washed with aqueous hydrogen
sulphide, then with alcohol, and finally with carbon disulphide,
and dried at 100—105°.

As will be seen from the tables, the agreement between the
different determinations for a given concentration is not so good
as is usual in a solubility determination, but this is probably
accounted for by slight differences in the composition of the solu-
tions, by differences in the size of the grains of the bismuth sulphide
(Ostwald, Zeitsch. fhysikal. Chem., 1900, 34, 495), and by slight
oxidation of the solutions.

The following table gives the solubility of dried precipitated

Concentration of

sodium sulphide,

mole/litre.

Number of
determinations.

Bismuth sulphide

dissolved : gram

per 100 c.c. of solution,

mean result.

0-5
10
1-5

5
6
3

0-0040-1-0-0005
0-0238 + 00016
0-1 023 ±0 0025

AND OF BISMrTH TRIOXIDE. 1763

bismuth sulphide in sodium sulphide solutions. The solutions are
greenish-yellow in colour.

In potassium sulphide solutions, the solubility for the same con-
centration is rather greater:

Concciitratiou of

potassium sulphide,

mole/litre.

Number of
detenniuations.

Bismuth sulphide

dissolved : gram

per 100 c.c. of solutiou,

mean result.

0-5
1-0
1-25

4
4
5

0-0042 + 0-OOOa
0-0337 + 00017
0-0639 + 00016

Since both freshly precipitated moist bismuth sulphide and dried
precipitated bismuth sulphide dissolve in potassium sulphide solu-
tions, it is difficult to explain the results obtained by Stone except
on the assumption that he used potassium hydrosulphide instead of
potassium sulphide solutions.

In the case of both sodium and potassium sulphides, the solu-
bility increases rapidly with the concentration of the alkali sulphide,
and is approximately proportional to the cube of the concentration.

The addition of alkali hydroxide to the alkali sulphide increases
the solubility greatly. The following tables show the effect of
sodium hydroxide and of potassium hydroxide on the solubility :

Soluhility of Bismuth Sulphide in Sodium Sulphide with the
addition, of Sodium Hydroxide.

Concentration
Concentration of of sodium
sodium sulphide, hydroxide,
mole/litre. mole/litre.

Number of
determinations.

Bismuth trisulphide

dissolved : gram per

100 c.c. of solution,

mean result.

0-5 10
1-0 10

7
4

0-018.5 + 0 0020
0 0838 ±0-0022

Solubility of Bismuth Sulphide in Potassium, Sulphide with the
addition of Potassium, Hydroxide.

Concentration

of potassium

sulphide,

mole/litre.

Concentration
of potassium
hydroxide,
mole/litre.

Number of
determinations.

Bismuth sulphide

dissolved : gram per

100 c.c. of solution,

mean result.

0-5
1-0
1-25

1-0
1-0
1-25

4
2
1

0-0240 + 0 0010
0-1230 + 0-0014
0-2354

The solvent action of alkali hydrosulphides and hydroxides on
precipitated bismuth sulphide was next investigated, since there
■was a possibility, judging from analogy to arsenic and antimony
sulphides, that it might dissolve to a slight extent.

The hydrosulphide solutions were prepared by saturating the
hydroxides with hydrogen sulphide, and expelling the excess of this
gas by a current of hydrogen. Dried precipitated bismuth sulphide

1764 KNOX: THE SOIUBILITY OF BISMUTH TRISULPHIDE

was shaken with N- and 2i\'-sodium hydrosulphide and potassium
hydrosulphide solutions for periods varying from twelve to twenty
days. The solid was allowed to settle completely, and the clear,
colourless, supernatant liquid withdrawn, faintly acidified with
hydrochloric acid, and saturated with hydrogen sulphide. No trace
of a precipitate or even of a brown coloration was obtained. On
adding sodium hydroxide to the remaining sodium hydrosulphide
solution, and again shaking for a few minutes, the solution assumed
the greenish-yellow colour characteristic of solutions of bismuth sul-
phide in alkali sulphides. Bismuth sulphide is, therefore, insoluble
in alkali hydrosulphides. This is aFso proved by the action of
hydrogen sulphide on solutions of bismuth sulphide in alkali
sulphides. On saturating such a solution with hydrogen sulphide,
the bismuth sulphide is completely precipitated.

For the solubility experiments in alkali hydroxides, it was
necessary that the bismuth sulphide used should contain traces
neither of the oxide, which is slightly soluble in alkali hydroxides
(see below), nor of the oxychloride, which reacts with alkali
hydroxides to a certain extent giving the hydroxide BiOgH (Herz
and Muhs, Zeitsch. cmorg. Chem., 1904, 39, 115). The first solu-
bility determinations, made with dried precipitated bismuth
sulphide, gave a solubility of the same order as that of bismvith
oxide in alkali hydroxides. This was subsequently found to be due
to slight oxidation of the sulphide during the drying, or to the
presence of traces of oxychloride. It was found very difficult to pre-
pare bismuth sulphide free from oxychloride by precipitation from
a hydrochloric acid solution. Prolonged washing with aqueous
hydrogen sulphide is necessary to remove the last traces of oxy-
chloride. In order to avoid these sources of error, freshly pre-
cipitated, moist bismuth sulphide, which had been repeatedly washed
with aqueous hydrogen sulphide and finally with air-free distilled
water, was shaken with N- and 2iV-sodium hydroxide for fifteen and
thirteen days respectively. On acidifying the clear solution with
hydrochloric acid and saturating with hydrogen sulphide, no trace
of a precipitate or brown coloration was obtained. Bismuth
sulphide is therefore insoluble in alkali hydroxides.

That the solutions of bismuth sulphide in alkali sulphides are
not colloidal is proved by the following considerations. The same
equilibrium is attained from both sides, and independently of the
time of shaking. The solutions are quite stable ; after months they
still retain bismuth and their characteristic greenish-yellow colour,
although they contain large quantities of electrolytes, which, as a
rule, act as more or less rapid precipitants for colloids. The bismuth
is not removed by filtering the solution through a very finely porous

AND OF BISMUTH TRIOXIDE. 17G5

cell. The fact that the solutions are prepared from dried pre-
cipitated bismuth sulphide is also against the probability of their
being colloidal. Finally, the properties of the solutions do not
agree with those of colloidal solutions of bismuth sulphide (Abegg's
Ilaiulhuch der anorg. t'Jtem., Ill, 3, 662).

Since bismuth sulphide is insoluble both in alkali hydrosulphides
and hydroxides, that is, does not form a complex anion -with either
SH' or OH', its solubility in alkali sulpliide solutions must be due
to the formation of a complex anion with the sulphur ion, S", of
these solutions. This view explains the increase in the ratio, bismuth
sulphide dissolved /concentration of alkali sulphide, with increasing
concentration of the alkali sulphide, and also the effect of the
addition of alkali hydroxide in increasing the solubility of bismuth
sulphide. The explanation is as follows. Sodium sulphide in
aqueous solution is hydrolysed to a very large extent into sodium
hydrosulphide and hydroxide (Kiister and Heberlein, Zeitsch.
anorg. Chem., 1905, 43, 53; Knox, loc. cit.) according to the
equation :

NaoS + HoO = NaHS + NaOH,

or, writing the ionic equation :

S" + HoO = HS' + OH',

and, since it is the salt of a weak acid and a strong base, the
hydrolysis must increase with dilution. The relative concentration
of the S"-ions must, therefore, diminish with dilution, and, since
the solubility of bismuth sulphide depends on the S"-ion concen-
tration, the ratio of bismuth sulphide dissolved to sodium sulphide
will also diminish with dilution. From the hydrolysis equation, it
is also evident that the addition of alkali hydroxide, by increasing
the concentration of OH'-ions, will diminish the degree of hydro-
lysis, thus increasing the concentration of the S''-ion, and hence the
solubility of bismuth sulphide in the alkali sulphide. The same
considerations apply also in the case of potassium sulphide. The
existence of the solid compounds KBiS2, NaBiS2 (Schneider, Fogg.
Ann., 1869, 136, 460; Milbauer, Zeitsch. anorg. Chem., 1905, 42,
433), and Bi2S3,4K2S,4HoO (Ditte, Compt. rend., 1895, 120, 186)
also confirms the view that the solubility is due to complex formation
with the S"-ion.

Bismuth sulphide, therefore, forms, like the corresponding arsenic
and antimony compounds, complex anions with the S"-ion, but not
to an appreciable extent with SH'- or OH'-ions. From the solu-
bility determinations alone, however, it is not possible to arrive at
the formula of the complex.

The importance of this reaction in analytical chemistry has

VOL. XCV. 6 A

1766 KXOX : THE SOLUBILITY OF BISMUTH TRISULPHIDE

already been emphasised by Stilhiian (Joe. cif.). In the separation
of the copper sub-groiip from the arsenic sub-group by means of
alkali sulphides, the quantitative determination of bismuth would
be vitiated, and small quantities of bismuth might easily be missed
altogether.

The action of sodium disuliohide and of ammoniixm sulphide solu-
iions on bismuth sulphide was also studied, in view of their
importance analytically in the sei^aration of the copper and arsenic
sub-groups.

The sodium disulphide solutions were prepared by dissolving the
requisite quantity of sulphur (crystallised from carbon disulphide)
in sodium sulphide solutions. In the solubility determinations,
dried precipitated bismuth sulphide was shaken with the sodium
disulphide solution until equilibrium was established. A definite
volume of the clear solution was then withdrawn, and acidified
with hydrochloric acid. The bismuth sulphide was precipitated
along with the excess of suljDhur. Hydrogen sulphide was passed
in until the supernatant liquid became clear, when the precipitate
was collected in a Gooch's crucible, washed with aqueous hydrogen
sulphide, then with alcohol, and finally with carbon disulphide,
dried, and weighed. The washing with carbon disulphide was
repeated until the weight was constant. As the mean of four
determinations, in which the times of shaking were varied greatly,
100 c.c. of iY -sodium disulphide solution were found to dissolve
0'0090 + 0'0010 gram of bismuth sulphide. This is only about a
third of the solubility in the corresponding strength of the mono-
sulphide. This result confirms the view that the solubility of
bismuth sulphide in alkali sulphides is due to the formation of a
complex anion with the S"-ion, since in polysulphide solutions a
large proportion of the S'^-ions are used up in forming the com-
plexes Sg", S3", etc., with the dissolved sulphur, and are, therefore,
not available for complex-formation with bismuth sulphide. In
solutions of the higher polysulphides, the solubility would be still
less than in the disulphide.

The ammonium sulphide solution was prepared in the same way
as the sodium sulphide, except that the hydrogen sulphide used to
saturate the ammonia solution was washed by ammonia of the same
strength, and the expulsion of the excess of hydrogen sulphide by
a current of hydrogen was omitted. In 2.V-ammonium sulphide,
which had been shaken with dried precipitated bismuth sulphide
for ten days, no trace of dissolved bismuth sulphide was found.
The exceedingly small concentration of S"-ions in ammonium
sulphide solutions (Knox, loc. cit.) explains the insolubility of
bismuth sulphide.

AND OF BISMUTH TRIOXIDE. 1767

Solubility of Bismuth Oxide in Sodium Hydroxide Solutions.

The bismutli oxide was prepcared either by igniting the basic
nitrate to low redness, or by precipitating the basic nitrate from
a solution of the normal nitrate by diluting with water, digesting
the precipitate on the water-bath repeatedly, first with water and
then with sodium hydroxide solutions, washing until free from
alkali, drying, and igniting. Both preparations gave the same
solubility. The sodium hydroxide solutions used were free from
carbonate.

The time of shaking required for the establishment of equilibrium
was much longer than in the case of the sulphide solutions. As
a rule, two to three weeks were allowed. The solubility deter-
minations were carried out in the same way as for the sulphide.
The clear saturated solutions were slightly acidified with hydro-
chloric acid, and the bismuth precipitated as sulphide. The results
are contained in the followinc: table :

Concentration nf

sodium hydroxide,

mole/litre.

Number of
determinations.

pel

Bismuth oxide
dissolved : f,'ram
100 c.c. of solution,
mean result.

i-0

2-0

3-0

7
6

5

0-0013 + 0'OOC2
0-0026±0-0002
0-0049 + 0-0005

The solutions were colourless, and showed no opalescence.

The solubility is nearly proportional to the concentration of the
sodium hydroxide. A few experiments with potassium hydroxide
showed that the solubility was much the same as in sodium
hydroxide. The same arguments against the colloidal nature of
the solutions hold as in the case of the sulphide solutions. Bismuth
trioxide, therefore, behaves towards strong bases as the anhydride
of a weak acid, but, in agreement with its more electropositive
character, to a much less extent than the corresponding oxides of
arsenic and antimony.

Chemical Department,

University of Aberdeen.

6 A 2

1768 KNOX : VOLUMETRIC ESTIMATION OF MERCURY AND THE

CXCV. — The Volumetric Estimation of Mercury and
the Estimation of Silver in Presence of Mercury.

By Joseph Knox (Carnegie Research Fellow of Aberdeen

University).

Rrpp and Krauss {Ber., 1902, 35, 2015) describe a volumetric
method for the estimation of mercury in a solution of mercuric
nitrate by titration with ammonium thiocyanate. The method is
the same as Volhard's method for silver, except that the solution
must be strongly acid with nitric acid.

The method has been used for some time by the students in this
laboratory; the mercuric nitrate solution used by them was made
by dissolving a weighed quantity of precipitated mercuric oxide in
excess of dilute nitric acid. As the results obtained were con-
sistently rather low, the following investigation was undertaken in
order to test the accuracy of Rupp and Krauss' method.

On testing the method by titrating a mercuric nitrate solution,
prepared by dissolving precipitated mercuric oxide or red, crystalline
mercuric oxide in cold dilute nitric acid, I obtained results for the
mercury from 04 to 1 per cent, lower than those calculated from
the weight of mercuric oxide used. The mercury in the solution
was also estimated gravimetrically as sulphide, and the results
agreed, within the limits of experimental error, with those calculated
from the weight of mercuric oxide dissolved. The mercuric sulphide
was collected in a Gooch's crucible, washed with water, alcohol,
and then with carbon disulphide until the weight was constant.
The explanation of the low results by the volumetric method was
found in the fact that the solutions obtained by dissolving mercuric
oxide in excess of cold dilute nitric acid invariably contained
mercurous nitrate, especially after standing for some time. The
effect of small quantities of mercurous salt on the volumetric result
is considerable, whereas the gravimetric result is scarcely affected.
Thus, for example, 216 grams of mercuric oxide would give 232*07
grams of mercuric sulphide. If the mercuric oxide contained 1 per
cent, of mercurous oxide, the gravimetric estimation as sulphide
would give 229"74 grams of mercuric sulphide -i- 2"24 grams of
mercurous sulphide = 23r98 grams, compared with 232-07 grams
from pure mercuric oxide, a difference of only 0'04 per cent. By
the volumetric method 216 grams of mercuric oxide would require
2000 c.c. of iY-ammonium thiocyanate, whereas if the mercuric
oxide contained 1 per cent, of mercurous oxide the amount of
thiocyanate required would be 1980 c.c. for the mercuric salt+ 1038

''estimation of silver in presence of mercury. 1769

c.c. for the mcrcurous salt= 199038 c.c, compared with 2000 c.c.
for pure mercixric oxide, a difference of 048 per cent.

As an example of tlie results actually obtained, the following
figures may be given. The first column gives the equivalent normal
concentration of the mercuric nitrate solutions calculated from
the weight of mercuric oxide used, the second column the con-
centration calculated from the gravimetric estimation of the
mercury as sulphide, and the third column the concentration cal-
culated from the volumetric analysis, on the assumption that all
the mercury was in the mercuric form. The ammonium thiocyanate
solutions used in the titrations were standardised from a silver
nitrate solution, the strength of which was found by estimating
the silver gravimetrically as chloride :

I. II. III.

1 0-2936 0-2935 0-2914

2 0-2972 0-2970 0-2968

3 0-1239 0-1238 0-1229

All these solutions gave a turbidity with hydrochloric acid, owing
to the precipitation of mercurous chloride.

Pure mercuric nitrate solutions were next prepared by
dissolving a weighed quantity of pure distilled mercury in
pure concentrated nitric acid. The solution was boiled for
a short time and diluted to a definite volume. These solutions
contained no mercurous salt even after standing several
weeks. The agreement between the results for the strength of
the mercuric nitrate solution, as calculated (1) from the weight
of mercury dissolved (first column), (2) from the gravimetric
estimation as mercuric sulphide (second column), and (3) from
the volumetric estimation (third column), is excellent. The volu-
metric results are calculated from the mean of several closely
agreeing titrations:

I. II. III.

1 0-1239 01240 01288

2 0-1559 0-1560 0-1559

The method of Rupp and Krauss, therefore, gives perfectly
accurate results with pure mercuric nitrate solutions.

Rupp and Krauss further describe a method for determining
silver and mercuric mercury together in a solution of their
nitrates. The total silver and mercury is determined by titration
with standard thiocyanate, whilst the silver is determined in
another portion of the solution by titration by Gay-Lussac's
method. The determination of the total silver and mercury by
thiocyanate is accurate. Thus it was found that 10 c.c. of
0"1559xY-mercuric nitrate and 35'07 c.c. of 0'09946A''-silver nitrate

1770 KNOX : VOLrMETUlC ESTIMATION OF MERCURY AND THE

required 3744 c.c. of 01084.V-ammonium tliiocyanafce, compared
with 37'3S c.c. calculated from the strengths of the silver and
mercury solutions.

It has long been known, however, that the determination of silver
by Gay-Lussac's method is inaccurate in presence of small quan-
tities of mercury, and impossible in presence of large quantities
(see, for example, Fresenius, Quant. Anal., 6th German Ed., Vol. I,
p. 309). This eflfect of mercuric salts is explained by the extremely
small extent to which mercuric chloride is dissociated electro-
lytically (Morse, Zcitsch. fhysikal. Chem., 1902, 41, 709; Buttle
and Hewitt, Trans., 1908, 93, 1405). Thus, on adding sodium
chloride to a mixture of silver and mercuric nitrates, both
of which are dissociated to a large extent in dilute solution, the
whole of the Cl'-ions will not be used to precipitate the silver as
chloride, but a definite proportion, depending on the solubility
product of silver chloride and on the dissociation constant of mer-
curic chloride, will unite with the Hg-*-ions to form undissociated
mercuric chloride. It is on this minute degree of electrolytic dis-
sociation of mercuric chloride that the solubility of silver chloride
in mercuric nitrate solutions also depends (Morse; Buttle and
Hewitt). Yet Rupp and Krauss state that 10 c.c. of iV/10-silver
nitrate and 10 c.c. of 0'2347iV-mercuric nitrate required 1001 c.c.
of 3'/10-sodium chloride. I have repeated many times the titration
of silver with sodium chloride by Gay-Lussac's method in presence
of varying quantities of mercuric nitrate, and found that the pre-
cipitation of the silver was not complete until 98 — 99 per cent, of
the mercuric nitrate had been converted into undissociated mercuric
chloride. Thus, for example, 10 c.c. of 009931iV^-silver nitrate
and 10 c.c. of 0"293o3"-mercuric nitrate required, in three different
experiments, 28-83, 28-90, and 28-81 c.c. of 0-1342iy-sodium
chloride, and 10 c.c. of 0-09931.T-silver nitrate and 5-05 c.c. of
02 9353' -mercuric nitrate required 18-30 c.c. of 0-1342xV-sodium
chloride. To convert both the silver and the mercuric salt com-
pletely into chlorides would have required, in the first case, 29-27
c.c, and in the second case, 18-44 c.c, of the sodium chloride
solution, whilst the silver salt alone should have required only
7-40 c.c. in each case. In presence of the mercuric salt, the pre-
cipitated silver chloride settles extremely slowly, so that a titration
occupies several days. For the estimation of the total silver and
mercury in a solution of the nitrates, the method of Rupp and
Krauss is, therefore, rapid and accurate. It is, however, useless
for the estimation of the metals separately.

For the volumetric estimation of silver in a solution containing
silver and mercuric nitrates, a method depending on the solubility

ESTIMATION OF SILVER I\ PRESENCE OF MERCURY. 1771

of silver chloride in potassium cyanide was used. The following
description of an experiment illustrates the method. Ten c.c. of
0"09979-.V-silver nitrate and 10 c.c. of 0'2935iV-mercuric nitrate were
mixed, and the silver was precipitated completely as chloride by
dilute hydrochloric acid. Sufficient hydrochloric acid was added to
convert both silver and mercury into chlorides. The silver chloride
was coagulated by heating on the water-bath with constant stirring,
cooled, and collected on a hardened filter paper. The precipitate
was washed with dilvite nitric acid, and then with water, until free
from chlorides, then paper and precipitate were transferred to a
beaker, 2507 c.c. of 0"0953iV-potassium cyanide were added, and
the silver chloride dissolved completely. The excess of potassium
cyanide was then titrated with 0"09979iV-silver nitrate until a
permanent turbidity appeared, 13"89 c.c. being required. This gives
01082 gram of silver in the solution, compared with 0'1077 gram
calculated from the strength of the silver nitrate solution used.
The results are always rather high, and this is probably due to the
escape of hydrogen cyanide during the solution of the silver
chloride, which occupies some time. The filter paper does not
interfere with the titration. The method, however, is neither so
accurate nor so convenient as the gravimetric method (see below).

Gravimetric Determination of Silver in Presence of Mercuric

Nitrate.

According to Fresenius (Quant. Anal., 6th German Ed., Vol. I,
p. 607), the precipitation of silver as chloride by hydrochloric acid
in presence of mercuric nitrate is never complete, owing to the solu-
bility of silver chloride in mercuric nitrate. Even when sufficient
hydrochloric acid is added to convert both silver and mercury into
chlorides, complete precipitation of the silver cannot be absolutely
depended upon. Menschutkin also {Anahjt. Chem., Eng. Ed., 1895,
p. 339) states that, in presence of mercuric nitrate, the seiDaration
of silver as silver chloride is inexact, as the results are affected
by the solubility of silver chloride in mercuric nitrate.

In the volumetric method given above, it is necessary that the
silver should be completely precipitated as chloride. I therefore
carried out a large number of gravimetric estimations of silver as
chloride in presence of widely varying quantities of mercuric
nitrate, and the results in all cases agreed with those obtained from
the same silver nitrate solutions without the addition of mercuric
nitrate. The method was the following. To the solution contain-
ing silver and mercuric nitrates, which always contained a little
free nitric acid, hydrochloric acid was added drop by drop with

1772

GUMMING : A METHOD FOR THE

stirring. The total quantity of hydrochloric acid added was very
slightly in excess of that required to convert both the silver and
the mercui-y into chlorides. The solution containing the precipitate
was heated on the water-bath with constant stirring to coagulate
the silver chloride, and allowed to cool completely. The clear
solution was again tested with a drop of hydrochloric acid to
ensure that precipitation was complete. The clear liquid was then
decanted through a Gooch's crucible, and the precipitate remaining
in the beaker washed several times with dilute nitric acid. The
precipitate was transferred to the crucible, washed several times
with cold water, and dried at 120°. The following table contains
the results of these determinations. The first column gives the
weight in grams of silver chloride from 25 c.c. of the silver nitrate
solution alone. The second column gives the amount of mercuric
nitrate added to 25 c.c. of the same silver nitrate solvition as in the
first column, and the third column gives the weight of silver
chloride precipitated from this mixture. The mercu^ric nitrate
solutions used contained no trace of mercurous salt.

I.

II.

III.

1

2

3

4

5

.... 0-3598
.... 0-3598
.... 0-3598
.... 0-3598
.... 0-3598

5 c.c

5
10
15
20
15
20
25
25

. of 0
, 0
, 0

,, 0
, 0

„ 0

„ 0
, 0
, 0

1239 iV-solution

1559

1239

1239 „

1239

5447

5447

1239

2935

0-3603
0-3597
0-3599
0-3598
0*3600

6

7

8

.... 0-3598
.... 0-3598
.... 0-3574

0-3601
0-3598
0-3573

9

.... 0-3620

0-3622

From these results it appears that the presence of mercuric
nitrate does not affect the gravimetric estimation of silver as
chloride, provided that the estimation is carried out as described
above. The statements of Fresenius and Menschutkin receive no
confirmation.

Chemical Department,

University of Aberdeen.

CXCVI. — A Method for the Measurement of Vaioour

Pressures.

By Alexander Charles Gumming.

A NUMBER of methods have been proposed and used for the
measurement of vapour pressures, such as those of salt hydrates,
but the only one which has found favour with subsequent workers

MEASUREMENT OF VAPOUR PRESSURES. 1773

is the differential tensimeter method. This has been described by
Frowein {Zeitsch. yhi/sikal. Chem., 1887, 1, 1), and the apparatus
is figured in most text-books of physical chemistry. Although
theoretically very simple, it is, in practice, a most unsatisfactory
instrument, and for some reason it is very difficult to obtain accurate
or even concordant results with it (compare Cohen, ibid., 1894, 14,
89). Andreae (ihid., 1891, 7, 241) has drawn attention to one
source of error. Since a solution or a hydrate gives up water
when the apparatus is evacuated, there is always a certain amount
of vapour in the side of the apparatus which contains the sub-
stance, and in the other side there will always remain enough air
to give a pressure equal to this vapour pressure. Only by long
continued evacuation can the last trace of air be removed, but
during the process the hydrate is always more or less dehydrated.

Other proposed methods (Pareau, " Pompbarometer," Inang.
Diss., 1875 ; Linebarger, Zeitsch. ph!/sikal. Chem., 1894, 13, 505 ;
Miiller-Erzbach, ibid., 1895, 17, 446) have not been adopted
either from difficulties in the manipulation, or on account of
inaccuracy. Lescceur (Ann. Chim. Plujs., 1889, [vi], 16, 378;
1890, [vi], 19, 533, et seq.) has used a method which differs
completely in principle from any other method. The hydrate
was placed in a glass vessel, and after some time the
vapour tension in the atmosphere above the hydrate was deter-
mined by an ordinary dewpoint method. Many of Lescoeur's
results are in fair accord with those obtained by other methods,
but in some cases there is no agreement, for example, for a
saturated solution of decahydrated sodium sulphate at 30" 1°, Cohen
found the pressure to be 2803 mm., whilst Lescceur at 30'0° found
24'8 mm. Such differences occur sufficiently often to make it
almost certain that there must be some inherent defect in Lescoeur's
method, and it may be noted that in the twenty years since its
publication it has not found application by others.

The author hopes to show in the present paper that it is possible
to base an accurate and easy method for the measurement of the
vapour tensions of hydrates and solutions on a determination of
the dewpoint under certain conditions. As the proposed method
resembles that of Lescceur in this respect, some reasons for the
inaccuracies in his results will be suggested after a description of
the method which has been used.

Experimental.

The principle of the method is to determine the dewpoint in
an atmosphere containing vapour in equilibrium with the solution
or solid under examination. The apparatus used consisted of a

r

GUMMING : A METHOD FOR THE

wide-mouthed glass bottle 7?, which contained a sample of the
hydrate or liquid. The bottle was fitted with a rubber cork 7),
through which passed a silver cylinder .4, closed at the lower end,
and a glass tube C, provided with a stopcock.

The silver cylinder, which was 2 cm. in diameter and 10 cm.
long, was fitted at the top with a three-holed cork, which carried
a thermometer and two glass tubes, arranged so that air could be
blown through a liquid in the cylinder.

The measurement of the vapour pressure of 44 '8 per cent.

sulphuric acid may be described
to illustrate the mode of experi-
ment. About 50 c.c. of the acid
were placed in the bottle and the
coi'k D inserted. The bottle was
exhausted by means of the water-
pump through G, and the tap
closed. The bottle was then
placed in a glass-fronted thermo-
stat up to the neck, and kept at
29'8° for some hours.

To find the dewpoint, the
silver tube A was two-thirds
filled with ether, and air blown
through at such a rate that the
temperature fell very slowly. A
dew began to form on the highly-
polished silver surface when the
thermometer indicated 17"5°.
The supply of air was then re-
duced and the temperature rose
slowly, until at 17'7° the last
trace of mist on the silver surface
had gone. The pressure at 17' 6°
is from Regnault's* values 15'0
mm. The vapour pressure of 44'8 per cent, sulphuric acid at
29-8° is therefore 15-0 mm.

The method has the marked advantage over other methods that
it is practically independent of the degree of exhaustion. It was
found that the same result was obtained to O'l mm. when the
exhaustion was carried out with a water-pump and with a mercury-
pump, and identical results were obtained after five, ten, and fifteen
minutes' exhaustion with a water-pump.

Vapour pressures of water and of .sulphuric acid solutions are, tluoughout this
I-aper, taken Irom Lando!t-Bornstein, Physikaliseh^chemische TabeUen (1905),

MEASUREMENT OF VAPOUR PRESSURES. 1775

Although the vapour pressure is theoretically almost independent
of the amount of air, it is expedient to evacuate the apparatus,
as otherwise the time required to attain equilibrium may be unduly
prolonged.

Further, if more than traces of air are left in the apparatus,
an actual error may be introduced by conduction of heat from the
outer wall to the silver cylinder. The tubes used were made of
silver and highly polished. When any patent polish was used, it
was found necessary to clean it off with alcohol before use and
polish finally with chamois leather; otherwise the tube quickly
became tarnished. Copper tubes were also tried, but were not as
satisfactory as the silver tubes.

Objection may be taken to the use of a rubber stopper, but the
amount of moisture in rubber corks is very small, and the results
show that the error, if any, was negligible. Ordinary corks are
obviously unsuitable, on account of the moisture in them.

The method was found very convenient and rapid in practicej
and it was desired to ascertain the degree of accuracy attainable.

The vapour pressures of sulphuric acid solutions are probably
known with greater accuracy than any other aqueous vapour
tensions, and experiments were therefore carried out at various
temperatures and with different concentrations.

Vapour Pressure of 448 per cent. Sulphuric Acid.

Temperature 19-4°. 20-1°. 25-9°. 29-8°. 30-8'.

Determined by author's method... 8-0 SI 11-9 1,5-0 16-0

From Regnault's values 7-8 8-2 117 14-9 15-9

„ Sorel's , 7-9 8-2 11-8 150 161

Vapour Pressure of 34'5 per cent. Sulphuric Acid.

Temperature 14-2°. 24 -2". 27 '9^ 30-9°.

Determined by author's method ... 8-9 1.5-1 19-1 227

From Regnault's values 8*8 15-3 19-0 22-5

Measurements have also been made in the case of certain salt
hydrates, and some of the results are given below. In all cases
the salt was free from any appreciable amount of impurity. It
was powdered, a portion of it partly dehydrated, and the whole
thoroughly mixed.

For the system CuS04,5H.20 - CuS04,3H20, Frowein's figures
are, at 20'1°, 4"9 mm.; at 25'9°, 7'8 mm. For the same
temperatures my results were 5'2 mm. and 7"8 mm. For the system
MgS04,7HoO-MgS04,6HoO, at 20-1°, the pressure found was 7-4
mm., as against 7' 7 mm. from Frowein's results. These results
are typical of the variations between the pressures found by the

1776 MEASUREMENT OF VAPOUR PRESSURES.

dewpoint method and the results given by Frowein. The differences
are small, and in no case has a difference of more than 0'4 mm.
been noticed.

It is uncertain what degree of accuracy is attainable with the
differential tensimeter method as used by Frowein. Andreae (loc.
cit.) has shown that in ordinary use a trace of air is left, but that
air could be completely removed by evacuation while the bulbs of
the apparatus were immersed in solid carbon dioxide. The mag-
nitude of the error introduced by neglect of this trace of air will
vary with the amount of moisture given off by the hydrate, the
rate at which it is given off, and other details of the particular
experiment. It is difficult, therefore, to assign even a probable
value to the experimental error involved in results such as those
of Frowein.

As an indication of the magnitude of the possible error from
residual air, it may be mentioned that Andreae found it to be
0'2 to 0'3 mm. in his experiments. A comparison of results with
those of Andreae was not attempted, as his measurements were
made on the differences in vapour pressure between different
hydrates, and do not include the actual vapour pressures of single
hydrates. The results obtained with sulphuric acid solutions prove
that the dewpoint method is accurate.

It was found that the equilibrium pressure was quickly attained
with solutions, and that more time was required for solid hydrates.
All the solutions so far examined have reached their equilibrium
pressure within an hour. The vapour pressure of a salt hydrate
does not usually become constant so quickly, and in some cases a
steady value is only obtained after one or more days. It was found,
particularly in the case of salt hydrates, that a slight error is
introduced if the readings succeed one another at all quickly, and
a reason for this may be suggested. When water is condensed on
the surface of the silver tube, the pressure in the apparatus is
reduced, and more vapour is supplied by the hydrate. The film
of moisture is vaporised when the tube is warmed, and time must
therefore be allowed for equilibrium to be re-established before
another reading is taken. With very slow alteration in the tem-
perature of the silver tube, and with an hour or more between
readings, it was found that variations between readings rarely
exceeded 0'1°. A difference of 01° at 0° is equivalent to a
difference of 0'03 mm.; at 10° to a difference of 0"06 mm.; and
at 20° to a difference of 0"11 mm. An accuracy of O'l mm. was
regarded as quite sufficient for present purposes. It is the inten-
tion of the author to endeavour to obtain a more delicate apparatus,
but the method as outUned above is sufficiently accurate for most

SOME MERCURY DERIVATIVES OF CAMPHOR. 1777

purposes, and a higher degree of accuracy means a corresponding
sacrifice in simplicity and speed.

Lescoeur appears to have taken little trouble to keep the tem-
perature constant, since he states that the vessel was kept in a
room the temperature of which did not vary more than 5° from
the temperature given.

In later experiments, he applied a correction by calculation when
the apparatus was not at the desired temperature. In his experi-
ments, the apparatus was not evacuated, and serious errors may
arise from this cause, particularly in cases where a long time is
required to attain the equilibrium pressure. In any case, it must
be better to remove most of the air, since the vapour pressure in
the immediate neighbourhood of the apparatus might otherwise
differ largely from that in other parts of the apparatus. There
are other minor sources of error, but the above are sufficien-t to
account for his results. It should be mentioned that in many, and
perhajDS in most, cases, Lescoeur's results will prove to be accurate,
but as the matter stands it is not known which results are
trustworthy.

The dewpoint method is particularly suited to the measurement
of aqueous vapour tensions, but it may also be applied to the
measurement of other vapour pressures.

It is to be applied to the measurement of vapour tensions
required in another investigation, and the author hopes to obtain
also a comparison of results for the vapour pressure of some salt
hydrates measured by the above method and by an accurate
differential tensimeter method.

Chemistry Department,

University of Edinburgh.

CXCVII. — Some Mercury Derivatives of Camphor.

By James Ernest Marsh and Robert de Jersey Fleming
Struthers.

In this paper an account is given of experiments made during the
past two years, some of the results of which have already been
briefly recorded (Proc, 1907, 23, 246; 1908, 24, 267). The work
is a consequence of the observation that an alkaline solution of
mercuric cyanide gives with acetone an insoluble mercury derivative
(Trans., 1905, 87, 1878). We obtained similar derivatives of other
ketones, but only with those which have a methyl group attached

1778 MARSH AND STRUTHERS :

to the carbonyl group. By using mercuric iodide instead of
mercuric cyanide, mercury derivatives of other ketones are obtained,
provided that the ketones contain hydrogen in the a-position with
respect to the carbonyl group. We have prepared in this way
mercury derivatives of acetone, acetophcnone, diethyl ketone, and
camphor, but not of benzophenone or fenchone. This reaction has
been studied mainly so far as it concerns camphor. We have
subjected camphor to the action of mercuric iodide in presence of
an alcoholic solution of potassium ethoxide and of an aqueous
solution of potassium hydroxide with and without the addition of
potassium iodide, and with and without the action of heat. By
the action of potassium ethoxide, and by the action of a cold
aqueoiis solution of potassium hydroxide, dimercuricamphor di-
iodide, CioHi40Hg2l2, is formed. On the other hand, by employing
heat, an aqueous solution of potassium hydroxide gives, in presence
of excess of potassium iodide, a more condensed compound, namely,
tetramercuritricamphor di-iodide, (CjoHi40)3Hg4lo. Further, in
the hot solution, we have obtained evidence of the formation of
the compound (CiQHj40)4Hg5l2 when the potassium iodide is not
in excess, and of the compound (CioHi40)5Hggl2 when the potassium
iodide is in defect.

Experimental.

Action of Mercuric Iodide on Camphor in Presence of Potassium

Ethoxide.

When mercuric iodide is added to a solution of sodium or
potassium ethoxides in alcohol, the red colour of the iodide dis-
appears, and a pale yellow precipitate takes its place. If, however,
camphor is dissolved in the solution, the mercuric iodide dissolves
without giving any precipitate. V5 Grams of potassium were
dissolved in 50 c.c. of absolute alcohol, 9 grams of camphor were
then added, and, by degrees, 13'5 grams of mercuric iodide. A
clear solution was obtained, which was poured into water, giving
a white precipitate. The mixture was then saturated with carbon
dioxide to prevent reduction to metallic mercury, which is brought
about by the action of alcohol on an aqueous alkaline solution of
mercuric iodide. The precipitate was collected, washed with water,
and dried, to remove excess of camphor. It was then digested
with an aqueous solution of potassium iodide to remove excess of
mercuric iodide, and again washed and dried. It weighed 6'5
grams. The above-described treatment is necessary for the
removal of the double salt, KHgl3,4CioH](;0 (described at the end
of this paper), which is formed from its constituents in alcoholic

1
i

SOME MERCURY DERIVATIVES OP CAMPHOR. 1779

solution. The qiiantities taken were in accordance with the

equation :

eCjoHicO + 4HgIo + 2K0Et =

CioHnOIoHgo + 2KHgl3,4C,oH,cO + 2CoH60.

Dimercuricamphor di-iodide was obtained as a nearly colourless,
amorphous powder. It is insoluble in alcohol, and its solubility
in the liquid when it is prepared is explained later. We have
obtained it in a purer form by two other methods. When prepared
by the above-mentioned method, its analysis gave a low value for
mercury and a high value for the other constituents. This is
doubtless due to the difficulty of getting rid entirely of the double
salt, which retains camphor even when heated for some time :

Found, C = 15-4; H = l-9; 1 = 31-8; Hg = 48-0.

CioHi^OIoHgo requires C = 14-9; H = l-7; 1 = 315;
Hg = 49'7 per cent.

A solution of sodium ethoxide in alcohol reacted in a precisely
similar way. An alcoholic solution of potassium hydroxide, how-
ever, acted rather differently. In this case, the mercuric iodide
did not readily pass into solution, and reduction to metallic mercuiy
appeared to take place.

Action of a Cold Aqueous Solution of Potassium Hydroxide on
Mercuric Iodide and Camphor.

When a cold solution of potassium hydroxide acts on mercuric
iodide alone, there is a certain amount of decomposition, with
formation of potassium iodide and a basic mercuric iodide, without
apparent change in the colour or density of the precipitate. In
presence of sufficient camphor, however, the red powder gradually
disappears, and its place is taken by a pale yellow precipitate,
which is specifically lighter. The method of preparation was as
follows. Fifty c.c. of A^-potassium hydroxide were mixed with 6'7
grams of mercuric iodide, and a solution of 0'75 gram of camphor
in a little petroleum added. The whole was then mechanically
shaken for several hours until the red powder had disappeared,
and its place was taken by a nearly colourless precipitate. The
point when the reaction is finished is easy to determine, as the
precipitate is fairly light, and the heavy red powder is seen below
it as long as any is present. The reaction is hastened by using a
more concentrated solution of potassium hydroxide. The mixture
was then freed from petroleum in a vacuum, filtered, washed, and
dried. The precipitate thus obtained does not appear to be a single
substance, and its composition varies according to the proportions of
the materials used. The amounts of mercury and iodine in different

17S0 MARSH AND STRUTHERS :

samples has varied from 50"1 to 536 per cent, of mercury and
28o to 24" 7 per cent, of iodine. The product with the lower
percentage of mercury was obtained by employing only 4'5 grams
of mercuric iodide. The yield was fairly constant, being about
5 grams for every gram of camphor used with the full amount of
mercuric iodide. The amounts were taken in accordance with the
following equation :

CioHieO + 3HgIo + 2KH0 = CioHj.OIoHg. + KgHgl^ + 2H2O.

According to this equation, two-thirds of the total mercury and
one-third of the total iodine should be found in the precipitate,
whilst there was actually found two-thirds of the total mercury,
but only one-quarter of the total iodine. It seems not
unlikely that the precipitate consisted mainly of the compound
CiQHi40*Hg2l2, together with a certain variable amount of a
compound, CioHj40'HgoO. This view receives support from the
action of a solution of potassium iodide on the substance; the
solution at once becomes alkaline, and by repeating the treatment
dimercuricamphor di-iodide is obtained. On analysis :

Found, 1 = 31-7; Hg = 49-2.

CioHj^OIgHgg requires I = 3r5; Hg = 49"7 per cent.

Since potassium hydroxide gives no precipitate with a solution
of mercuric iodide in potassium iodide, it was thought that the
dimercuricamphor iodide might be obtained pure by using the
compound K2Hgl4 in the alkaline solution. No action at all was
observed in the cold, even after several months, with this mixture.
Action, however, readily takes place when the mixture is heated on
a water-bath, but with the formation of a different compound.

Action of an Alkaline Solution of the Compound K2Hgl4 on
Camphor at 100°.

Camphor, dissolved in a little petroleum, was heated with
an alkaline solution of the compound K2Hgl4 on a water-bath.
It was ascertained that the alkaline solution had no action on the
petroleum alone. With the camphor, in a short time a yellow
precipitate began to form, and gradually increased in quantity.
The action was allowed to proceed for twenty-four hours or longer.
The precipitate was then collected, washed, and dried at 100° to
remove water and camphor. The amount of alkali employed was
about 100 c.c. of 33 per cent, potassium hydroxide for every
10 grams of camphor. The amount of mercuric iodide was varied
in different experiments, and in each case was dissolved in the

SOME MERCURY DERIVATIVES OF CAMPHOR. 1781

requisite amount of potassium iodide. The yield (in grams) is
given in the following table : I'lecipitate.

Camplior.

Mercuric iodide.

Found.

Calculated.

10

16-6

13-3

14

10

27-5

17-5

22

10

30

19

25

10

45

22

83

The calculated yield is obtained from the equation :

SCioHjoO + 4UgIo + 6KII0 = (C,oni40)3lIg,I. + 6KI + GHoO.

Accordingly, every 10 grams of camphor should require 40 grams
of mercuric iodide, and give 33 grams of the compound. It is
seen that the yield apjDroaches nearest to the theoretical amount
when the camphor is in the greatest excess. The precipitate, even
after prolonged washing, retains from two to three per cent, of
fixed mineral matter. Ignition left potassium iodide, but extraction
with a large bulk of water gave, after evaporation, not iodide, but
carbonate. It was estimated as potassium sulphate by ignition with
sulphuric acid. Analysis of the precipitate gave:. I = 16"6;
Hg = 5r6; K2C03 = 2'5. If we allow for the 25 per cent, of
impurity, the composition is :

Found, 1 = 170; Hg = 52-9.

C3{)H4203l2Hg4 requires 1 = 169; ng = 532 per cent.

The method of prejjaration just described requires a considerable
amount of potassium iodide, and since this iodide is also found in
the reaction, there is eventually much more of it than is necessary
to keep the mercury iodide in solution. It is probable that it is
this large amount of potassium iodide which tends to prevent the
completion of the reaction. The plan was therefore tried of making
the experiment progressive, namely, by starting with small amounts
of camphor, the compound KoHgl4, and alkali, and adding con-
tinually fresh charges of camphor, mercuric iodide, and alkali. In
this way, the original potassium iodide, together with that formed
in the reaction, serves to dissolve the mercuric iodide if it is not
added too quickly, or in too large a quantity at a time. Starting
with 66 grams of potassium iodide, we obtained from 15 grams
of camphor and 45 grams of mercuric iodide, added in five stages,
36 grams (theory = 37) of the compound. In another experiment,
using 2 grams of potassium iodide, then 21 grams of camphor and
63 grams of mercuric iodide in 13 stages, we obtained 49 grams
(theory = 51) of the precipitate. The yield will be seen to be much
better than in the earlier experiments, and, in fact, leaves nothing
to be desired. The composition of the precipitate was also found
to be the same :

Found, 1 = 16-7; Hg = 51-2; K2C03 = 2-2.

VOL. XCV. 6 B

1782 MARSH AND STRUTHERS :

In this case also, potassium iodide still accumulates in the mother
liquor. Thus, in the second experiment, the 49 grams of pre-
cipitate contained 25 grams of mercury and 85 grams of iodine.
The 63 grams of mercuric iodide employed contained 27" 7 grams of
mercury and 353 grams of iodine. Hence the solution, which at
starting only contained 2 grams of potassium iodide, will in the
end contain 32 grams, and only 6 grams of mercuric iodide. This
accumulation of potassium iodide may be prevented by employing
as the fresh charges a mixture of mercuric iodide and chloride or
a mixture of potassium iodide and mercuric chloride. It was not
found possible to obtain any mercviry derivative of camphor by the
use of mercuric chloride alone, but the addition of a very small
quantity of potassium iodide was sufficient to start the reaction.
With defect of potassium iodide the compound is mixed with
mercuric oxide. The substance (CiQHj40)3Hg4l2 was obtained as
a pale yellow, amorphous powder. It is scarcely affected by the
ordinary solvents; alcohol has a slight solvent action, and carbon
disulphide partly dissolves it without separating it into any simpler
constituents. It is slowly attacked and decomposed by an aqueous
solution of potassium iodide, and is rapidly decomposed by
potassium iodide in acetone solution. The halogen and hydrocyanic
acids readily decompose it into camphor and a mercuric salt. The
diluted oxygen acids have little or no action. Concentrated nitric
acid oxidises it, giving camphoric acid, melting at 186° (anhydride,
m. p. 220°) ; concentrated sulphuric acid decomposes it, with
separation of mercuric iodide. A more complete study of the
action of glacial acetic acid was made.

Action of Glacial Acetic Acid on the Comjiound (CioIIj40)3Hg4l2.

When the compound is heated with glacial acetic acid, the whole
dissolves, and, on cooling, mercuric iodide crystallises out. The
filtrate gives a clear mixture with water, and on evaporation dries
to a colourless, transparent glass. It was not obtained in a
form suitable for analysis, but the experiments recorded below
leave no doubt that it is the acetate of mercuricamphor,
CjQHjr^O'Hg'O'CO'CHg. The action of the hot acetic acid may be
represented by the following equation :

(CjoH,40)3Hg4l2 + 3C2H4O2 = Hglo + SCjoHjsO-Hg-CgHgOg.

When cold glacial acetic acid acts on the compound, a different
reaction takes place. The yellow colonr of the compound dis-
appears, and a white precipitate and a colourless solution result.
The change is complete in about an hour. It suggests by its
appearance, not the extraction of a coloured from a colourless con-
stituent in a mixture, but rather the occurrence of a definite

SOME MERCURY DERIVATIVES OF CAMPHOR. 1783

reaction. After an hour or longer, the precipitate was collected,
washed, and dried. It was analysed, and found to be dimercuri-
camphor di-iodide, CiyHj40Hg2l2 :

Found, C = 14-7; H = l-9; 1 = 31-3; Hg = 490.

CioHjiOIoHgo requires 0 = 149; H = l-7; 1 = 31-5;
Hg = 49-7 per cent.

The filtrate, on dilution with water, gave a slight further pre-
cipitate. The solution resembled closely, especially in its reaction
with potassium iodide, the similar solution obtained with hot acetic
acid. On the supposition, therefore, that it contains mercuri-
camphor acetate, the following equation represents the action of
cold acetic acid :
(C,oHi40)3Hg,l2 + 2C2H4O0 = CioHnOIoHg. + 2CioHi50-Hg-C2H302.

The theoretical yield of dimercuricamphor di-iodide is accordingly
53 per cent. In two experiments, we found 50 and 52 per cent,
respectively, this being the total precipitate after adding water.

Dimercuricamphor di-iodide is a colourless, amorphous powder,
insoluble in water and other neutral solvents. It can be sublimed
without melting, and without apparent decomposition. It is not
dissolved or decomposed by an aqueous solution of potassium iodide.
Whilst neither alcohol nor acetone dissolve the substance, a mixture
of it and potassium iodide in molecular proportions is readily
soluble in alcohol, and almost without limit in acetone. These
observations show that the dimercuricamphor di-iodide is not present
as such in the original substance, since both an aqueous solution of
potassium iodide and acetone and potassium iodide decompose that
substance. Hence the original substance is not a mixture contain-
ing dimercuricamphor di-iodide as a constituent, but is most
probably a definite compound.

There is no reason to suppose that the dimercuricamphor di-iodide
obtained in this way is a different compound from that obtained
by the action of potassium ethoxide or of a cold solution of
potassium hydroxide on a mixture of camphor and mercuric iodide.
It was at first thought that the compound produced by the action
of potassium ethoxide was different because it gave a clear solution
in alcohol. But since potassium iodide is formed at the same time,
the substance dissolved is not dimercuricamphor di-iodide, but the
double salt, CioHi40'Hg.2lo,KI, which, as previously mentioned, is
readily soluble in alcohol. Probably the equation explaining the
action of potassium ethoxide is best represented as :

^CioHjgO + 3HgIo + 2K0Et =

CioH,40-HgJo,KI + KHgl3,4Ci^HieO + 2C2H60.

Here both the double salts are soluble in alcohol.

6 B 2

17S4 MARSH AND STRUTHERS :

Mercur'icamphor Iodide, CjoHjsO'Hgl, and its Double Salt,
CjoHi.O-Hgl^Hgl..

The solution obtained by the action of glacial acetic acid on the
original substance, and presiimcd to contain mercuricamphor
acetate, was, after dilution with water, treated with a solution of
potassium iodide, when a thick, yellow precipitate was formed.
This precipitate redissolved with excess of jDotassium iodide, being
thereby decomposed. The addition of potassium iodide was stopped
when it ceased to give any further precipitate, and the orange-
yellow substance was collected. It proved to be a double salt of
mercuricamphor iodide with mercuric iodide, of the formula
CjoHi50-IIgI,Hgl2, which was not quite pure. Analysis gave :

Found, C = 130; H = r9; 1 = 38-4; Hg = 42-6.

CioHijOIsHgg requires C = 12-9; H = l-6; 1 = 40-8;
Hg = 42-9 per cent.

It may be represented as being formed by the equation :
2CioHi50-Hg-aH30. + SKI + CgH^O, =

CioHi,0-HgI,HgIo + SaH^OoK + CjoHjeO.

It will be seen that in order to obtain this compound, mercuric
iodide has to be formed at the expense of the camphor compound.
To prevent this, a solution of mercuric iodide in potassium iodide
was used to precipitate the compound, with the effect of more
than doubling the yield of it. Although potassium iodide in the
acetic acid solution decomposes the compound with separation of
camphor, in neutral solution it only removes the mercviric iodide
from the dovible salt without decomposing it further. In this way,
mercuricamphor iodide, CioHj^O-Hgl, is left as a nearly colourless
precipitate. It was washed, dried, and analysed :

Found, C = 24-8; H = 3-2; 1 = 26-5; Hg = 42-0.

CjoHisOIHg requires 0 = 251; H = 3-l; 1 = 26-5;
Hg = 4r8 per cent.

Mercuricam.'phor iodide is soluble in ethyl acetate, and crystal-
lises from it in very minute, colourless crystals, melting at 184°.
It is decomposed by glacial acetic acid. The deficiency of iodine
in the analysis of the double salt is probably due to the removal
of some mercuric iodide from it by vising a slight excess of potassium
iodide. The same cause has raised the amount of carbon without
appreciably affecting the percentage of mercury.

M ercu.ri''am'phor Bromide, CioHi^O'HgBr.

Ten grams of the compound (CjoHj40)3Hg4l2 were treated with
15 CO. of cold glacial acetic acid for one hour, then diluted with

SOME MERCURY DERIVATIVES OF CAMPHOR. 17S5

water, and filtered. To the filtrate was added a solution of
potassium bromide in water, as long as it gave a precipitate,
rS Grams of potassium bromide were required. The white pre-
cipitate was collected, washed, and dried. It weighed 4"5 grams
(theory = 5*7) :

Found, Br = 18-2; Hg = 45-8.

CiyHjr,OBrHg requires Br = 18'5; ng = 46"4 per cent.

Mercurlcamphor bromide is insoluble in water, but readily
soluble in glacial acetic acid, from which it separates in colourless,
transparent crystals, melting at 220 — -221°. It is soluble to a
certain extent in dilute acetic acid ; hence the full amount is not
precipitated when potassium bromide is added to the acid solution.

Merciiricamiihor Chloride, C^QlIj,r,0'HgCl.

As before, 10 grams of the compound (CjoHi(jO)3Hg4l2 were
digested for one hour with cold glacial acetic acid, and the mixture
was diluted with water and filtered. The filtrate was precipitated
by the gradual addition of a solution of sodium chloride; 0"7 gram
of sodium chloride was just in excess. The precipitate, after
washing and drying, weighed 4 grams, whilst theory requires
5 grams [(CioHj,,0)3lIg4l^, gives 2C,oPIj50'HgCl], and the amount
given by 0"7 gram of sodium chloride should be 4'8 grams. The
chloride, although insoluble in water, is sparingly soluble in dilute
acetic acid. It crystallises well from glacial acetic acid. Before
crystallisation it melted at 219°, and afterwards at 222°:

Found, CI = 9-2; Hg = 51-8.

CioHj^OClHg requires CI -9-2; Hg = 51-7 per cent.

Professor Bowman reports on the crystals as follows : " Mostly
aggregates of flattish needles, with pointed ends, having a longi-
tudinal cleavage. The material is biaxial, and small crystals and
cleavage flakes show under the microscope a division into two
halves by a longitudinal twin junction. The extinction is nearly
straight. Through each half emerges a single optic axis inclined
slightly in the plane transverse to the needles. The cr}^^stals show
only imperfect extinction between crossed Nicols, and appeir to
consist of overlapping lamellae. The double refraction is moderate,
and is compensated by a quartz wedge inserted parallel to the length
of the needles."

Mercuricam'pJior Oxide, (C;oHj50IIg)20.

The existence of the iodide, bromide, and chloride of mercuri-
camphor indicated the possibility of obtaining the base or oxide,
of which they may be regarded as salts. This base was obtained

17S6 MARSH AND STRUTHERS :

by precipitating the acetate with pure sodium hydroxide. It is
necessary for this purpose that the hydroxide should contain no
chloride; if it does, the chloride is precipitated along with the
base.

Seven grams of the compound (CiQHj40)3Hg4l2 were digested for
an hour with 15 c.c. of cold glacial acetic acid, the mixture being
then diluted with water, and filtered. The filtrate was mixed with
100 c.c. of 10 per cent, pure sodium hydroxide, when a white,
granular precipitate was formed, which, when washed and dried,
weighed 2'3 grams (theory = 3'3). The base is probably slightly
soluble in water, as potassium iodide gave a precipitate with the
solution from which the base had been separated :

Found, C = 331; H = 4-l; Hg = 55-4.
C2oH3o03Hg2 requires C = 33'4; H = 4"2; Hg = 55"7 per cent.

The oxide is readily soluble in alcohol or carbon disulphide, but
does not crystallise. From carbon disulphide it is left, on evapora-
tion, as a clear, transparent glass. On heating above 100°, it loses
camphor, with formation apparently of the oxide (CjoHj40)2HggO.
From the base by the action of acids, and from the chloride by
double decomposition, other salts of mercuricamphor have been
prepared, for example, the sulphate, nitrate, oxalate, and benzoate,
but have not as yet been completely examined.

Action of Iodine on the Compound (C]oHj40)3Hg4l2 :
Di-iodocamphor.

Twelve grams of the mercuricamphor compound were treated
with a cold solution of 8 grams of iodine in benzene. Mercuric
iodide soon began to separate, and when the action was apparently
finished, the filtered solution was evaporated in a current of carbon
dioxide in the dark. Pale yellow, hard crystals separated, which
weighed 6 grams (theory = 8 grams). The substance was recrystal-
lised from petroleum, when it melted at 109°. Analysis showed it
to be di-iodocamphor :

Found, C = 30-6; H = 3-9; 1 = 62-7.

C10H14I2 requires C = 29-7; H = 3-5; 1 = 62-8 per cent.

The rotation in 28 per cent, chloroform solution was about
Wd + 2^°' ^^t the accurate determination was difficult, owing to
th") separation of iodine.

Di-iodocamphor decomposes on keeping, especially in a closed
bottle; it is more stable when freely exposed to air. Its solution
in petroleum or chloroform gives free iodine on exposure to light,
and its solution in petroleum also becomes coloured by iodine on

SOME MERCURY DERIVATIVES OF CAMPHOR. 1787

warming. The production of di-iodocamplior in tins way show^s that
in the original substance two hydrogen atoms of the camphor have
been replaced by mercury.

Action of Aqueous rotassium Hydroxide on the Compound
(C,oHHO)3HgJ3.

By heating the compound (CioH]40)3Hg4l2 with potassium
hydroxide containing potassium iodide on a water-bath, a substance
containing 12 to 13 per cent, of iodine was formed. Further, by
prolonged heating with potassium hydroxide and removing the
alkali whenever it was found to contain iodine, a compound free
from iodine was eventually obtained. This substance, which is
colourless, has the composition represented by the formula
(C,oHj,0).,Hg30:

Found, C = 26-l; H = 3-2; Hg = 641.
CooHosO^Hga requires C = 26-2; H = 30; Hg = 65-5 per cent.

We have obtained compovxnds poorer in iodine similar to those
mentioned above by diminishing the amount of potassium iodide
used in the preparation of the original svibstance. For example,
when mercuric chloride was employed with very little potassium
iodide (3 grams of camphor, 5 3 grams of mercuric iodide, and
1 gram of potassium iodide), alcohol extracted from the product of
the reaction a substance closely agreeing in composition with the
formula (CjoHj^O)3Hgcl2 :

Found, 1 = 11-3; Hg = 54-1.

C5(,Hyo05l2Hgg requires I = 11'5; Hg = 54'4 per cent.

Hence it seems likely that the action of potassium hydroxide
and iodide on the substance (CioHj40)3Hg4l2 is, in the first place, to
form the more highly condensed compounds {C^^^■^^0)^iAgr^2y which
contains 13" 7 per cent, of iodine, and {C^^^■^^0)'^B.g^2.'} ^'^^ that the
latter compound is decomposed by the action of the potassium
hydroxide in accordance with the following equations :

4(CioHi,0)3Hg J2 = 3(C,oH,,0),Hg,l2 + Hgl2.

5(CjoHj,0),Hg3l2 = 4(Ci„Hi,0),Hgol2 + Hgl2.

(CioHi,0)5Hgel2 + 2KH0 = 2{Q,,-H.,,0)^^g^0 + CjoHj^O + 2KI.

The condensation of camphor with mercuric iodide in presence
of alkali takes place, in the first instance, with formation of the
compound CjoHi40Hgol2- On heating, a further condensation
occurs, with the formation of the compound {C-^QB.-^fi)^gJ.2, and
there is evidence of the probable existence of the com-
pounds (CioHi40)4Hg5l2 and (Cj(jHj40)-Hg(;l2. The compound
(CjoHj40)2Hg3l2 in the series is missing, but is represented by the
compound (CioHi40)2Hg30. The mercury in all the compounds

1788 SOME MERCURY DERIVATIVES OF CAMPHOR.

investigated and described in tliis paper appears in tlie mercuric
state. In no case when the compounds have been decomposed by
a halogen acid has the mercury separated as a mercurous salt.

Double Salt of the Gofjipou?id KHgIg with Camphor of Cry&tal-
lisation, KHglg^CjoHjgO.

Mercuric iodide dissolves in water containing two molecular
proportions of potassium iodide for every one of mercuric iodide.
In certain organic solvents, such as ethers, mercuric iodide dissolves
along with one molecular proportion of potassium iodide; that is,
as the salt KHgIg, instead of KoHgl^. Consequently, when an
aqueous solution of the latter is shaken with ethyl acetate or ethyl
formate, the salt KHglg is dissolved, and if the solution is fairly
concentrated, the ethereal solution becomes heavier than the
aqueous, and sinks to the bottom. The salt, after evaporation of
the ethyl formate, was analysed :

Found, Hgl2 = 73-0; KI = 26-9.

KHgIg requires IIgl2 = 73"2; KI = 26"8 per cent.

The same salt was also obtained from ethyl acetate. An experi-
ment was made to ascertain to what extent the salt K2Hgl4 is
decomposed when its aqueous solution is shaken with an ester.

3'3 Grams of potassium iodide and 4'5 grams of mercuric iodide
were dissolved in 10 c.c. of water, and the solution shaken with
10 c.c. of ethyl acetate. The lower ester layer gave on evaporation
4"3 grams of the salt KHgIg, and the upper aqueous layer gave
3'5 grams of a mixture of potassium iodide, with a little mercuric
iodide. The numbers are fairly in accordance with the following
equation :

3K2HgI, = 2KHgl3 + (KI)4Hgl2.
In ether. In water.

When a solution of camphor in alcohol is added to an aqueous
solution of mercuric iodide in potassium iodide, oily drops soon
begin to form on the surface of the liquid, and after a time solidify
to a mass of crystals. The crystals are hard, not at all of a
camphor-like nature, and are of a pale yellow colour. Analysis
showed that they had the composition KIIgl3,4CioHigO :

Found, Camphor = 49-5; Hgl2 = 36-9; KI = 13-5.

C^oHe^OJaHgK requires Camphor = 49-5; Hgl2 = 36-9;
KI = 13"5 per cent.

When camphor, mercuric iodide, and potassium iodide are dig-

OPTICALLY ACTIVE SUBSTANCES, ETC. 178[)

solved in a inodei-ate amount of alcohol, in the proportions indicated
by the formula, the whole sets to a mass of crystals. The crystals
are quite stable unless exposed for some time to the air, when they
lose their crystalline form and criimblc to powder. Their melting
point is 65°, and their rotatory power is that of the camphor
contained in them.

Univeksity Labokatoky,

OXFOBD.

CXCVIII. — 02:)tically Active Substances Containing no
Asymmetric Atom. 1 - MethylcyoXohexyUdcne - 4-
acetic Acid.

By William Henry Perkin, William Jackson Pope, and
Otto Wallacii.

A perusal of van't Hoff's early work on optical activity makes it clear
that he adopted the view, first advanced by Pasteur, that the opticai
activity of amorphous substances is duo to enantiomorphism of mole-
cular configuration. Van't Hoff and Le Bel developed Pasteur's con-
clusion by introducing a definite theory of the configuration of carbon,
compounds, and showed that the enantiomorphism of molecular con-
figuration possessed by all known optically active substances could be
correlated with the presence of asymmetric carbon atoms in the
molecule.

The optical activity is, in fact, not, as is still sometimes stated, due
to the presence of an asymmetric carbon atom, but originates in the
enantiomorphous molecular configuration. The identification of a
particular carbon atom in the molecule as asymmetric is merely a
convenient method for recognising enantiomorphism of molecular
configuration.

Van't Hoif realised that organic substances are capable of formula-
tion which, whiLst possessing enantiomorphous molecular configurations,
contain no asymmetric atom, and quoted, as an instance, the formula

-p^^C'CIC\r>^ as that of a substance which should be of enantio-
morphous molecular configuration, and therefore capable of exhibiting
optical activity in the amorphous state, although its molequl© contains
po asymmetric atom.

1790 PERKIiV, POPE, AND WALLACH : OPTICALLY ACTIVE

The statement is sometimes made that iuosite, which is optically
active in solution and has the configuration

OH H

(2) (^

HO /Y I \ OH

1/ H OH\l

Cu (J)

I \ H H /Y

^© ©^

I I

OH OH

contains no asymmetric carbon atom. This, however, seems to
involve a misapplication of the definition of an asymmetric carbon
atom. The carbon atom (1) is separately attached to the two systems,
OH H H H

-©-©- ^^^ -©-©-

II II

H OH OH OH

which differ configurationally in the same way respectively as do the
(/-tartaric and me.sotartaric acids ; although these two groups thus
differ in configuration, they are not enantiomorphously related. The
carbon atom (1) being attached to these two configurationally dis-
similar groups and to two others, namely, H and OH, is directly joined
to four quite dissimilar groups, and is hence asymmetric ; in the same
way, it will be seen that the other five carbon atoms in the inosite
molecule are also asymmetric.

No case has, in fact, been experimentally realised of a substance
exhibiting optical activity in the amorphous state and containing no
asymmetric carbon (nitrogen, sulphur, selenium, tin, or silicon) atom.

In view of the theoretical importance attaching to the discovery of
substances exhibiting optical activity in the amorphous condition, and
hence possessing enantiomorphous molecular configurations, but con-
taining no asymmetric atom, it appeared desirable to attempt, by
modern synthetic methods, the preparation of such compounds. The
study of allene derivatives such as were considered by van't Hoff pre-
sented obvious disadvantages ; the facility with which such substances
undergo isomeric change and become converted into acetylene deriv-
atives, and their tendency to combine with water, etc., to yield ethylene
derivatives, might be expected to introduce experimental difficulties
which would be desirably avoided, Perkin and Pope (Proc, 1906,
22, 107 ; Trans , 1908, 93, 1075) therefore synthesised the 1-methyl-
c?/c^ohexylidene-4-acetic acid,

^^s^n^CHg'CHg-v^p.p^H
H^^^OH,-ChY ^ ^CO.,H

SUBSTANCES CONTAINING NO ASYMMETRIC ATOM. 1791

which contains no asymmetric carbon atom, but which, in accordance
with the van't Huff conception, possesses an enantiomorphous
molecular configuration, and attempted its resolution into optically
active components. By a curious coincidence, Marckwald and Meth
were at the same time engaged upon the synthesis of the same compound
for the same purpose ; they obtained an acid, melting at 40 — 41°, to
which they assigned the constitution given above and effected its
resolution into optically active components (Ber., 1900, 39,1171).
The acid melting at 40 — 41° was, however, quite different from that
prepared by Ferkin and Pope, which melts at 66"^,* and the latter
authors suggested (Proc, 1906, 22, 107) that Marckwald and Meth's
acid is the isomeric l-niethyl-A^-c^c^ohexene-4-acetic acid of the con-
stitution

As the carbon atom numbered (1) in the latter constitutional
formula is obviously attached to four constitutionally dissimilar
groups it is asymmetric in the ordinary sense ; the resolution of such
a synthetic product into optic;illy active components therefore merely
illustrates again the optical activity of substances which contain an
asymmetric carbon atom in the molecule.

The difference of opinion briefly referred to above gave rise to a
long controversy, and led to an extended series of experimental investi-
gations (Marckwald and Meth, Ber., 1906, 39, 1171, 2035, 2404;
Wallach, Annalen, 1907, 313, 311; 1909, 365, 255; Perkin and
Pope, Trans., 1908, 93, 1075 ; Harding, Haworth, and Perkin,
Trans., 1908, 93, 1943; Hope and Perkin, Trans., 1909, 95, 1360)
The final result of this work has been to prove conclusively that the
original view taken by Perkin and Pope was correct ; the acid melting
at 66° is the true l-methylc?/c^ohexylidene-4-acetic acid, whilst the acid
melting at 40 — 41°, which Marckwald and Meth supposed to be the
latter acid, is the l-methyl-A'''-cyc^ohexene-4-acetic acid, the graphic
formula of which contains an asymmetric carbon atom. The resolu-
tion effected by Marckwald and Meth thus failed to yield a substance
exhibiting optical activity and containing no asymmetric atom.

The close study devoted to the two isomeric acids under discussion
led to simplifications in the preparation of l-methylc?/c^ohexylidene-4-
acetic acid (Wallach, Annalen, 1909, 365, 266), so that large quanti-
ties of this acid could be readily obtained for subjection to the treat-
ment usually employed for the resolution of externally compensated
acids into their optically active components. Owing to peculiarities
in the behaviour of the substance, its resolution presented considerable
difficulty, but we ultimately succeeded in separating the d- and
* The melting point, 70°, originally given is somewhat too high.

1702 PERKIN, POPE, AND WALLACH : OPTICALLY ACTIVE

/-components of l-methylcyc/ohexylidene-4-ac'etic acid in a state of
purity. "We are thus able to describe the first case of an optically
active substance which possesses an enautiomorphous molecular con-
figuration, although its constitutional formula contains no asymmetric
atom.

In discussing the molecular configuration of 1-methylcyc/ohexylidene-
4-acetic acid, it is convenient to adopt the rigid, but doubtless in-
correct, view that the four valency bonds attached to the methane
carbon atom in the molecule of a methane derivative are directed
towards the apices of a regular tetrahedron, of which the carbon atom
mentioned occupies the centre. The actual conditions, apart from the
fact that they are dynamic and not static as just premised, are
probably far less symmetrical than is indicated by our assumption ;
since, however, the space relations which give rise to the molecular
enantiomorphism of the new acid can be readily elucidated on the basis
of a symmetrical and rigid configuration for methane derivatives,
nothing, for present purposes, is to be gained by introducing the
more complicated, although doubtless more accurate, conditions indicated
abov^

The configuration of l-methylcyc^ohexylidene-4-acetic acid may be
represented in the following manner :

9

.H (c)
.0/
7 \CO,H (d)

8

in which those bonds represented by unbroken lines all lie in one
plane, and those represented by broken lines lie in a plane perpen-
dicular to the first ; if the continuous lines represent bonds which lie
in the horizontal plane of the paper, the broken lines stand for bonds
which lie in the vertical plane passing through the carbon atoms
numbered 1, 4, and 7. It will now be seen that the plane of the
paper which contains the continuous line bonds is not a plane of
symmetry of the solid configuration, because the hydrogen atom
marked (a), which lies outside that plane, is not repeated on the other
side of the plane, the symmetrical position being occupied by the methyl
group (b). Similarly, the vertical plane remarked above is not a plane
of symmetry of the configuration, because the groups (c) and (d), of
diffei'ent compositions, occupy symmetrical positions on two sides of
the plane ; in the same way, it can be shown that no other plane is a
plane of symmetry of the configuration as above represented.
Further, no directions can be distinguished as axes of symmetry of
the solid configuration, nor can any point be located within it as a
centre of symmetry,

(b) CH3,^

.CHg— CHgv
\G<( \c:::::;:;;.

(a) H^'

' 1 \CH2— CHg/ 4

SUBSTANCES CONTAINING NO ASYMMETRIC ATOM. 1793

It is thus seen that, even when a highly symmetrical configuration
is attributed to methane derivatives, the configuration assignable to
l-niethyIfyc/ohexylidene-4-acetic acid possesses neither planes, axes,
nor a centre of symmetry. The absence of all these elements of sym-
metry is more than is requisite to determine the enantiomorphism of
the contiguration.

From the above discussion it will be observed that the configuration
of l-methylc_yc^ohexylidene-4-acetic acid is enantiomorphous, even under
the highly symmetrical condition represented by placing the carbon
atoms numbered 1 to 8 and the hydrogen atom (c) in the plane of the'
paper and tlie carbon atom numbered 9 and the hydrogen atom (a) in
the plane, perpendicular thereto, referred to above. The enantio-
morphism would indeed persist if the hydrogen atoms (a) and (c) and
the carbon atoms 8 and 9 were centred at the apices of a regular
tetrahedron.

The conviction that the structural formulae assigned to chemical
substances imitate with considerable approximation to truth the real
nature of molecular constitution was appreciably deepened by the in-
troduction of the theory of the configuration of methane derivatives
by van't Hoff and Le Bel ; the development of the theory by Wisli-
cenus, so as to embrace the configuration of ethylene derivatives, and
by von Baeyer, in connexion with polymethylene derivatives, has
strengthened the view that the constitutional formulae of organic
chemistry represent very closely the actual atomic arrangement of
molecular complexes. The considerations which led to the work
described in the present paper involved, as has been seen, the develop-
ment of the original simple geometrical conception of the space con-
tiguration of methane and ethylene derivatives to an extent which
may appear extreme. The fact that we have been able to show
a close correspondence between the anticipations thus derived
and the experimental results must be regarded as an independent
demonstration of the fidelity with which constitutional formulae
picture molecular constitutions.

Resolution of \-Methylcyc\ohexylidene-i-acetic Acid.

The resolution of externally compensated l-methylc^/c^ohexylidene 4-
acetic acid into its optically active components is attended with some
difliculty, owing, in the main, to the very feeble acidic properties of
the substance. The inactive acid thus crystallises unchanged from
solutions in the fairly powerful base, 1-tetrahydroquinaldine, and can be
extracted by appropriate neutral solvents from its mixtures with many
of the optically active alkaloids. A clue to a successful mode of reso-
lution was, however, ultimately derived from the observation that on

1794 PERKIX, POPE, AND VVALLACH : OPTICALLY ACTIVE

mixing aqueous solutions of bmicine hydrochloride and sodium
l-methylcyc^ohexylidene-4-acetate a copious separation of an oil
occurs ; although this oily salt does not crystallise readily, the fact of
its formation can be utilised for the isolation of the two enantio-
morphously related acids.

As the result of a large amount of preliminary work, the following
method was finally adopted for the resolution of the externally com-
pensated acid. To a hot aqueous solution of two molecular propor-
tions of externally compensated sodium l-methylcycfohexylidene-4-
acetate is added a hot aqueous solution of slightly less than one
molecular proportion of brucine hydrochloride ; during admixture,
alcohol is added in just sufficient quantity to prevent the solution
becoming turbid by the separation of an oily salt. On allowing the
solution to cool slowly, an oil begins to separate, which, by persistent
scratching with a glass rod, or better, by inoculation with crystalline
salt obtained in a previous operation, may be caused to crystallise. In
accordance with the experience of Pope and Peachey in connexion with
the resolution of externally compensated bases (Trans., 1899, 75,
1066), it was to be expected that the crystalline salt which separated
should be the least soluble of which the formation is possible in the
system. The crystalline salt which separates under these conditions
does, indeed, consist, in the main, of one product, nimely, of brucine
Z-l-methylc2/c/ohexylidene-4-acetate, so that the change can be expressed
by the equation :

NaOH,(/A + NaOH,;A + ;B,HC1 = IBIA + NaOH,HCl + N"aOH,cZA.

As will be pointed out later, however, a complicating factor is intro-
duced, in that the two S4.1ts, ^B^A and IBdA, behave as if they were
partially isomorphous and form solid solutions.

The operation dt^scribed above yields a crystalline separation, which
has the composition of brucine ^-l-mei,hylcycZohexylidene-4-acetate,
but which, on recrystallisation, is found to bo by no means homo-
geneous; thus, in one case, on fractionally crystallising the separation
obtained as described above from dilute alcohol in such a manner that
the original separation was divided into five fractions, the con-
secutive fractions gave the following specific rotatory powers in
1 per cent, alcoholic solutions: [a ]d -447°, -22-0°, -40-7°, -237°,
and -33-6°.

The manner in which in these and a number of other trials the
specific rotatory powers change from fraction to fraction indicates
(1) that the original separation is a mixture of at least two substances,
and (2) that the resolution of the mixture by recrystallisation does not
follow the ordinary course ; the separation is, in tact, complicated by
the exhibition of behaviour somewhat similar to that observed with

SUBSTANCES CONTAINING NO ASYMMETRIC ATOM. 1795

mixtures of two substances which tend to form solid solutions, and
readily yield supersaturated solutions. Since the two compounds
present in the mixtures are presumably the I- and cZ-l-methylcyc^o-
hexylidene-4-acetates of ^-brucine, it was, however, indicated by
these results that some degree of separation could be effected by frac-
tional crystallisation. Considerable quantities of the first separation
of crystalline salt, obtained as above described, were therefore sub-
jected to systematic fractional crystallisation from very dilute alcohol;
the specific rotatory power of each fraction as it was separated was
ascertained, and the numerous fractions were sorted into portions of
approximately the same rotatory power. After a preliminary separa-
tion in this way into separate fractions of fairly uniform rotatory
power, the systematic fractional crystallisation was repeated. As the
final product of the prolonged application of this tedious process, a
highly laevorotatory salt was ultimately obtained, the rotatory power
of which was unaltered by subsequent crystallisation. The material
thus obtained gives all the ordinary iiulications of homogeneity, and
separates from dilute alcoholic solution in elongated, colourless, rect-
angular prisms; it melts at 97 — 100° when dried in the air, and after
expelling the water of crystallisation by heating at about 85° com-
mences to melt at 74°. As its properties appeared unaffected by
further recrystallisatiou, it was regarded as the pure salt, ^brucine
M-methylcycfohexylidene-4-acetate.

Brucine Idsvo-l-Meihylcyclohexi/Hdene-iacetate,

A considerable quantity of salt answering to the above description
having been accumulated, the whole was crystallised from dilute
alcohol, and the following analyses and determinations of rotatory
power made on the substance thus obtained :

0-3900, heated at 85°, lost 0-0242 HgO. HgO^ 6-21.

0-0790, air-dried salt, gave 0-1902 CUg and 0-0522 R.p.

Subtracting H.,0 = 6-21; C = 73-00; H = 7 14.
C^oii^QO^'N^,2H^6 requires H2O-6-I7; C = 7002; H - 7-35 per cent.

For the determinations of the rotatory power, shown in the table
below, the substance was made up to 20-05 c.c. with the solvent, and a
2-dcm. tube employed in each case.

Substance

{^ram.

Solvent.

On.

Wo.

0 1553

Absolute alcohol

-0 90"

-58-1

0-1570

J> »)

-0-91

-58-1

0-3983

}) a

-1 98

-49-8

0 5680

M n

-266

-46-9

01ti83

Methylal

-1-32

-78-6

01458

Water

-0-66

-38-6

17 96 (PERKIN, POPE, AND WALLACH : OPTICALLY ACTIVE

It thus appears that the specific rotatory power diminishes with
incieasiug concentration in alcoholic solution, that the specific rotatory
power is much higher in methylal solution, and that in water, in
•which alone the salt may be supposed to be practically completely
dissociated, the specific rotatory power has the lowest value.

In view of the difficulty which attends the preparation of the salt
characterised by the above constants, it was deemed advisable to
subject the whole mass of m iterial to further fractional crystallisation
from dilute alcohol in order to make quite sure that its rotatory
j)Ower had attained a constant value. It was therefore crystallised
four times from absolute alcohol, and the following determination of
the rotatory power made with the product :

0'1528 gram, made up to 20"05 c.c. with absolute alcohol, gave
ttu —0-89° in a 2-dcm. tube ; whence [a]o -58"4°.

The material was then subjected to another and fifth crystallisa-
tion from the same solvent, and the product found to give the following
results on determination of its rotatory power :

01 494 gram, made up to 20'05 c.c. with absolute alcohol, gave
cd -0 87° in a 2-dcm. tube; whence [a.]^ —58-4°.

Since in a 0"75 per cent, alcoholic solution the salt exhibited the
specific rotatory power [ajn -581°, as quoted above, and after four
And five recrystallisations the values [aju -58-4° and - 58*4° were
obtained, these being experimentally identical with the first, little
doubt seemed possible concerning the homogeneity of the substance.
The followiner work, however, showed that this conclusion is incorrect.

On decomposing a small portion of the salt by addition of
hydrochloric acid, a sample of acid was obtained which melted at
51 — 52°, and gave the followiug result on determination of its
rotatory power :

0"1253 gram, made up to 2005 c.c. with absolute alcohol, gave
tto - 0-97° in a 2-dcm. tube ; whence [o]d - 77'G°.

The main quantity of the salt, which was in the form of stout,
crystalline prisms, was next treated with hydrochloric acid, and the
precipitated acid filtered ; associated with it, however, was some
brucine hydrochloride, which could not be conveniently washed out
with water. The whole mass was therefore warmed with sodium
carbonate solution, and, after filtration, the acid was precipitated by
hydrochloric acid, collected, washed, and dried. The acid thus obtained
melted at 475— 49-5°, and gave the following results on determination
of its specific rotation :

0"1509 gram, made up to 2005 c.c. with absolute alcohol, gave
Ou - I'Kf' in a 2-dcm. tube ; whence [a]„ - 73"7°.

The residue left after warming the crude acid with sodium carbonate

SUBSTANCES CONTAINING NO ASYMMETRIC ATOM. 1797

solution as above described still contained acid ; this was extracted by
successive treatments with hydrochloric acid and sodium carbonate
solution, and melted very sharply at 52-5 — 53° It gave the following
results on determination of its rotatory power :

01459 gram, made up to 20-05 c.c. with absolute alcohol, gave
od - 1'18° in a 2-dcm. tube ; whence [a]^ - 81 '1°.

It is thus seen that the salt which yields acid of specific rotatory
power [a]o -77"6'^ gives, when the acid is separated in two fractions
as described above, samples having the specific rotatory powers,
[ajo -73-7° and -81-1° respectively.

In view of the unsaturated character of the acid, it seemed
advisable to ascertain whether the above variations in rotatory power
were caused by optical inversion during the liberation of the acid from
the brucine salt. A quantity of the acid having the specific rotatory
power [a]D - 73*7° was therefore distilled in a current of steam ; the
acid separated f I'om the distillate was found to have the specific rotatory
power [ajo - 74'0°. A further portion of the same sample of acid
was next heated for ten hours on the water-bath with excess of a 10
per cent, sodium carbonate solution ; during this treatment the solu-
tion became brown in colour, but the acid subsequently separated
from it was found to exhibit the specific rotatory power of [a]o - 71*9°.
These results indicate that the optical activity of the acid is prac-
tically unaffected by somewhat drastic treatment, and show that the
observed variations in rotatory power cannot be attributed to the
occurrence of optical inversion.

The explanation of the anomalous behaviour of the brucine salt
appears to be as follows. It is seen that prolonged fractional crystal-
lisation is necessary in order to obtain a brucine salt of constant rota-
tory power, namely, [aj^ -58"1° in a 0'75 per cent, absolute alcoholic
solution ; it is also observed that the salt is not homogeneous, because
the two fractions of acid separated from it have the rotatory powers
of [ajo - 73*7° and — 81"1° respectively. Taken together, these facts
indicate that the salt of specific rotatory power [a]o -58"1° is an
equilibrium mixture of brucine I- and (i-l-methylcyc'^ohexylidene-4-
acetates which is not resolvable by further fractional crystallisation
from dilute alcohol under the conditions established ; the slowness
with which the maximum rotatory power [aj^ - 58'4° is attained
during prolonged fractional crystallisation suggests that the two salts
form solid solutions. This is also in accordance with the facts that
both contain the same proportion of water of crystallisation, and that
an approximately complete resolution of the externally compensated acid
is not effected by the original crystallisation with one-half a mole-
cular proportion of brucine. It was also observed that on decom-

VOL. XCV. 6 C

1798 PERKIN, POPE, AND WAI.LACH : OPTICALLY ACTIVE

posiug the salt of [a],, -584°, the first portion of acid separated has
a lower rotatory power, [aj^ - 73"7°, than that which separated last,
namely, [ajp —81 "P. This indicates that during the crystallisation of
the brucine salt the salt with the l£evo-acid first separated in a state
of practical pui-ity, and that subsequently the mixture of the two
salts was deposited on the former as a kind of nucleus ; since the
crystals ultimately formed are quite massive, the outer layers were
first decomposed by the hydrochloric acid, giving acid of the lower
rotatory power, whilst the inner kernel was only decomposed by
further treatment, and yielded acid of the higher rotatory power,
Wd -81-1°

As no solvent other than dilute alcohol appears to be available for
the fractional crystallisation of the brucine salt, it was useless, in
view of the conclusions just derived, to attempt the further purifica-
tion of the Isevo-acid by the aid of the brucine salt. It is shown
later, however, that the enantiomorphously related acid has the
specific rotatory power [ajp +81'4°, so that the acid giving the
value [aji, -81'1° represents the pure ^-l-methylc«/c^ohexylidene-4-
acetic acid.

The small difference in rotatory power between the pure laevo-acid
of [a]o - 81*1° and that of [a]o - 77'6° yielded by the final crop of
brucine salt, together with the large percentage of brucine contained
in the brucine salt, rendered it certain that the specific rotatory
powers observed with the brucine salt are practically the values
appertaining to pure brucine ^-l-methylc?/c?ohexylidene-4-acetate, It
seemed, however, desirable to check the numbers by preparing the
latter salt from acid of [a]u -81*1° by crystallising the components
together from dilute alcohol. The pure salt was thus obtained in
colourless, highly lustrous prisms having the properties already
described in connexion with the slightly impure salt ; the following
determination of rotatory power was made :

0*1534 gram, made up to 20*05 c.c. with absolute alcohol, gave
ttD - 0-8'J° in a 2-dcm. tube ; whence [aj^ - 58-2°.

Brucine dextro-l-Methylcyclohexr/lideneA-acetate,

After the separation of the Ifevo-acid from the externally compen-
sated substance in the manner described above, the mother liquors are
treated with hydrochloric acid and the crude rM-methylc?/c?ohexylidene-
acetic acid separated ; it is convenient to mix with it acid recovered
from the fractions of brucine salt of low rotatory power to which
reference has been made above. In this way a pure mixture of the d-
and ^acids can be obtained which has a specific rotatory power of about

SUBSTANCES CONTAINING NO ASYMMETRIC ATOM. 1799

+ 30% and, although the salt formed by brucine with the hevo-acid is
much less soluble than that formed with the dextro-acid, the isolation
of pure bruciue (/-l-methylcyc^ohexylideneacetate is possible. The acid
of specific rotatory power of about [a],, + 30° is dissolved in dilute
alcohol with the addition of an equivalent quintity cf pure brucine, and
the salt formed subjected to prolonged fractional crystallisation from
the same solvent. It is advisable so to adjust the concentrations of
the solutions that crystallisation does not occur until the liquid is
cold ; under these conditions the salt of the l<Evo-acid tends to separate
in massive crystals, whilst that of the dextro-acid crystallises in aggre-
gates of light feathery needles. It is thus possible to effect a partial
separation by mechanical means, but the final purification of the salt
of the dextro-acid must be completed by fractional crystallisation
alone. In one series of fractionations a sample of salt was first
isolated which exhibited the specific rotatory power [aj^ - 2 2 '6°, in
alcoholic solution. Eight subsequent crystallisations of this material
yielded samples having the specific rotatory powers of [a]u — 18"7°,
- 16-9°, - 16-3°, - 13-5% - 14-6% - 12-8°, -10-4°, and - 11-5° respec-
tively. The apparently irregular fluctuations of the specific rotatory
powers of the successive crystallisations were at first difiicult to under-
stand, but were ultimately traced to the fact that the rotatory power
of the pure salt diminishes very rapidly with increase of concentration
of the solution. The last three values quoted above thus refer to pure
brucine c^-l-methylc^c^ohexylidene-'l-acetate.

This salt crystallises in colourless, feathery needles from dilute
alcoholic solution, and melts at 85 — 86° ; after drying at 70 — 80° it
begins to melt at 76°, but the melting point is very indefinite. This is
possibly to be attributed to the substance melting as a mere mixture
of the component base and acid :

0-5530, heated at 70—80° lost 0-0408 H^O. H.^^ 7-38.

0-0806, air-dned salt, gave 0-1929 COg and 0-0560 IIoO.

Subtracting H.0== 7 -38; C = 70-53; H=7-50.
C32H^oO,5N2,2H26 requires Hp = 6-17; C = 7002; H = 7-35 per cent.

For the determinations of the rotatory power, quoted in the table
below, the substance was made up to 20-05 c.c. with the solvent, and
a 2-dcm. tube employed in each case.

Substance.

grain.

Solvent.

Od.

[«]..

0-23 43

Absolute alcohol

-0-27°

-11-5°

0-4015

}) >f

-0-16

-3-9

0-5548

ij * J

-008

-1-4

1-0404

+ 0-25

+ 2-4

0-1404

iiethylai

-0-31

-22-1

0-1404

Water

-0 04

-2-9

It is interesting to note that the specific rotatory power of this salt

G C 2

1800 PKRKIX, POPE, AND WALLACE : OPTICALLY ACTIVE

varies with the concentration and the solvent in just the same direc-
tions as that of the brncine salt of the Ijevo-acid. In alcoholic solu-
tions the lajvorotatinn diminishes with increasing concentration until
in a 5 per cent, solution the salt is dextrorotatory, just as in the pre-
vious case the rotatory power in methylal solution is much higher than
that in aqueous solutions.

The two brucine salts are converted into oils by the addition of
small proportions of alcohol, acetone, or ethyl acetate, and are extremely
soluble in these and most other oi'ganic solvents.

\sevo-l-3feth!/lcyc\ohexi/lidene-4:-acetic Acid,

As already indicated above, the purest samples of this acid separated
from its brucine salt are still contaminated with traces of the enantio-
morphously related isomeride ; it forms minute, colourless, crystalline
scales, and cannot be conveniently crystallised from any of the ordinary
solvents. It melts very sharply at 52*5 — 53°, whilst the externally
compensated acid melts at 66°, and its melting point is depressed by
the presence of the externally compensated substance. Specimens of
mixtures of the two active acids exhibiting the specific rotatoxy
powers [ajo 12-3°, 24-2°, 52-8°, 737°, and 77-6° me't respectively at
61°, 42—57°, 43—44-5°, 47-5- 49-5°, and 51— 52°, so that the eutectic
mixture has a considerably lower melting point than either the pui'e
active or the pure externally compensated acid ; the melting point
curve of mixtures of the dextro- and Isevo-acid is thus of the type
depicted in Roozeboom's Fig. 7 {Zeitsch. 2)hysikal. Chem., 1899, 28,
508), and indicates that the partially compensated substances melt as
mixtures of optically active and racemic compounds.

The following determinations of rotatory power were made, the
substance being made up to 20"05 c.c. with the solvent, and a 2-dcm.
tube being employed in each case :

Substance.

gram.

Solvent.

tto.

[a]...

0-1459

Absolute alcohol

-1-18°

-81-r

0-1471

)) >>

-1-19

-81-1

0-3195

)) 1-1

-2-48

-77-8

0-1505

Methylal

-1-12

-74-6

0-1616

Ether

-1-20

-74-4

dextro-1-Methylcyclohexylidene-i-aceiic Acid.

This acid, as stated above, has been obtained more easily and in a
state of slightly higher purity than its enantiomorphously related
isomeride. It has the same melting point of 52-5 — 53°, and its mix-
tures with the externally compensated acid behave just as dp those of

i

SUBSTANCES CONTAINING NO ASYMMETRIC ATOM. 1801

the laevo-isomeride. The following determinations of rotatory power
were made, the substance being made up to 20'05 c.c. with the solvent,
and a 2-dcm. tube being employed in each case :

Substance
gram. Solvent. Od- [oJe

01453

Absolute alcohol

+ 1-18"'

+ 81-4'

0-2957

»» »»

+ 2-30

+ 78-0

0-1487

Methylal

+ 1-12

+ 75-5

0-14-78

Ether

+ 1-11

+ 75-3

The fact that the above values are slightly higher than the corre-
sponding figures for the enantiomorphously related acid is the ouly
indication yet obtained of the rather greater degree of purity of the
preparations of the dexti-o-acid.

On dissolving equal quantities of the two optically active acids
melting at 52-5 — 53° in light petroleum and evaporating to dryness,
the racemic acid was obtained melting at 62'5 — 63°; that this melting
point is rather lower than that of the pure externally compensated
acid, namely, 66°, is obviously due to the mixture, which weighed
only a few milligrams, containing a slight excess of one of the
component acids.

The fact, established by the work detailed in the foregoing pages,
that substances of enantiomorphous molecular coufigui-atiou can now
be prepared which exhibit optical activity in solution but yet contain
no asymmetric carbon atom, suggests a mode of investigating intra-
molecular change which should have interesting results. The d- and
?-raethylc?/c/ohexylidene-4-acetic acids owe their optical activity to the
possession of au enantiomorphous molecular configui'ation of the most
general kind, namely, one not associated with the presence of an asym-
metric atom, and should be convertible into the potentially active
1-methylcyc/ohexeneacetic acid described by Marchwald and Meth,
the optical activity of which is to be correlated with the presence of
an asymmetric carbon atom. This conversion has not hitherto been
described, and we have made a number of experiments in order to
establish the conditions under which it occurs.

After heating 0-5 gram of racemic l-methylc2/c^ohexylidene-4-acetic
acid with 10 c.c. of water and 2 grams of sodium hydroxide for live
hours on the water-bath, or with 10 c.c. of aniline for three hours at
100°, the original acid can be recovered unchanged. Similarly, on
boiling 1 gram of the sodium salt of the inactive acid with 2 grams of
aniline hydrochloride and 20 c.c. of alcohol during two hours, the
original acid is found to be unaltered. On boiling 0-5 gram of
l-methylc^c^ohexylidene-4-acetic acid with 20 c.c. of dilute sulphuric
acid for three hours, 0-4 gram of the original acid was i-ecovered un-
changed, together with traces of Marckwald and Meth's 1 methyl-
ct/c/ohexene-4-acetic acid, melting at 41°. In another experiment,

1802 BOYD AND KXOWLTON : THE ACTION OF AW]\IONIA

0"5 gram of the inactive hexylidene acid melting at 64° was boiled
for thiee hours with 10 c.c. of dilute sulphuric acid with the addi-
tion of sufficient alcohol for solution ; on subsequent distillation with
steam, a mixture of acid and ester was obtained, which, when hydro-
lysed, gave a mixture of the original acid with traces of the acid
melting at 41°.

Acting on the indications thus obtained, 0*5 gram of racemic
l-methylc?/cZohexylidene-4-acetic acid was heated for three hours on the
water-bath with a mixture of 4 grams of sulphuric acid, 1 gram of
water, and 5 c.c. of alcohol ; approximately equal quantities of acid
and ester were isolated from the product. The acid consisted in the
main of Marckwald and Meth's l-methyl-A^-c2/c^ohexene-4-acetic acid,
melting at 41°, and the ester also yielded, on hydrolysis with
alcoholic soda, a product consisting pi'incipally of the same acid.

A method is thus now available for the conversion of l-methylcyc^o-
hexylidene-4-acetic acid into the isomeric l-methyl-A^-c?/r;Zohexene-4-
acetic acid. We are now studying this conversion, using the optically
active hexylidene acids, together with several chemical changes of an
additive character, as a result of which thejeuantiomorphous molecular
configuration, containing no asymmetric atom, becomes converted into
an enantiomorphous configuration of the well-known type which is
associated with the presence of one or more asymmetric carbon atoms.

Our thanks are due to Dr. John Read for the care with which he
has carried out much of the experimental work involved in the present
paper.

Chemical Department, The Chemical Laboratoky, The Ukiveiisity,
The University, The University, Gottingen.

Manchester. Cambridge.

CXCIX. — The Action of Ammonia on the Glycide Aryl
Ethei^s. Fart I. o-Tolyloxypropanolamines.

By David Runciman Boyd and Herbert Stanley Knowlton.

The action of ammonia on substances of the type of ethylene oxide
was originally studied by Wurtz {Annalen, 1860, 114, 51). The
reaction has since been reinvestigated by Knorr (Ber., 1897, 30,
909), who succeeded in isolating the primary, secondary, and
tertiary ethanolamines in a pure condition.

Knorr has also studied the action of ammonia on glycide (Ber.,

ON THE GLYCIDE ARYL ETHERS. PART I. 1803

1899, 32, 750), and obtained y-amino-o)3-dibydroxypropane, along
with secondary and tertiary bases which were not isolated.

The present paper contains an account of the action of ammonia
on glycidc o-tolyl ether. In this case, a primary, a secondary, and
a tertiary base are readily isolated. Definite evidence has not
so far been obtained with regard to the position which the amino-
group takes up in the new molecule, but from analogy to the
case of glycide, and in view of the results obtained by Krassusky in
the case of the butylene oxides {ComiH. rend., 1908, 146, 236),
it appears probable that the primary base is ^-ami7io-fi' -o-tolyloxy-
isoprupi/l alcohol, C7H7-0-CH2-CH(OH)-CH2'NH2.

Experimental.
Glycide o-Tolyl Ether, 0<^^ ^ ^ ^7^7.

o-Cresol (80 grams) was dissolved in about 500 c.c. of water
containing excess of sodium hydroxide, and rather more than the
theoretical quantity of epichlorohydrin was added to the cold
solution. After the mixture had been kept for about four days,
with occasional stirring, the heavy oil which had separated was
extracted with ether, the ethereal solution dried and evaporated,
and the oil which remained w^as fractionated under diminished
pressure.

In this way, the glycide ether was obtained as a colourless oil,
boiling at 136°/ 17 mm., and, with slight decomposition, at 248°
under atmospheric pressure. The yield was about 28 grams.

The glycide o-tolyl ether so prej^ared still contained traces of
chlorine. It was therefore warmed on the water-bath with solid
sodium hydroxide, and again fractionated under diminished
pressure (compare Boyd and Marie, Trans., 1908, 93, 840). The
fraction analysed boiled at 134"5°/14 mm. :

0-2813 gave 0-7523 COo and 0-1872 HoO. C = 72-94; H = 7-46.
C10H10O2 requires C = 73-12; H = 7-38 per cent.

Action of Ammonia on Glycide o-Tolyl Ether.

If glycide o-tolyl ether is kept for some days in contact with a
concentrated aqueous solution of ammonia, it changes into a crystal-
line mass, which consists chiefly of the tertiary base, trihydroxytri-
o-tolyloxytripropylamine, whilst the primary base is present in the
aqueous solution.

A more convenient and rapid method of bringing about the
reaction consists in adding to the mixture of glycide o-tolyl ether

1804 KOYD AND KNOWLTON: THE ACTION OF AMMONIA

aud ammonia a sufl&cient quantity of alcohol to give a clear solution.
After about forty-eight hours at the ordinary temperature, the
glycide ether is completely transformed into a mixture of primary,
secondary, and tertiary bases. The end of the reaction can be
recognised by pouring a few drops of the aqueous alcoholic solution
into water. If the reaction is finished, the oily precipitate which
is at first produced will be found to solidify rapidly. The mixture
is then heated on a water-bath to expel the alcohol and ammonia,
water being added occasionally to prevent the solution becoming
too concentrated.

In the course of the evaporation, an oil separates which solidifies
on cooling. The solid is collected and used for the preparation of
the secondary and tertiary bases. The filtrate is then evaporated
on the water-bath to a small volume. The syru^py residue left
after most of the water has been expelled consists of a mixture of
the primary base and its carbonate, the latter being formed during
the process of evaporation.

In one experiment, 181 gi'ams of glycide o-tolyl ether were
mixed with 170 c.c. of concentrated aqueous ammonia and an equal
volume of alcohol. As a result, 16"5 grams of the hydrochloride of
the primary base (equal to about 14 grams of free base) were
obtained, 1'4 grams of the secondary base, and about 3 grams of
tertiary base.

fi-Amino-^'-o-tolyloxT/isopropT/l Alcohol, CnjHigOg'NHg.

The hydi'o chloride of this base is obtained as a crystalline pre-
cipitate on adding concentrated hydrochloric acid to the mixture
of free base and carbonate prepared as above described. It can
be recrystallised by dissolving in alcohol, and adding about two
volumes of ether. It then separates in colourless plates, which
soften at 131°, but do not melt completely until 254°. Repeated
fractional crystallisation does not alter this melting point:

0-2750 gave 15-6 c.c. N2 (moist) at 20° and 750 mm. N = 6-40.
CioHisOaNjHCl requires N = 6-44 per cent.

The salt is extremely readily soluble in cold water, giving a
neutral solution. It is precipitated from a concentrated aqueous
solution on addition of hydrochloric acid.

The free base was prepared by treating a concentrated aqueous
solution of the hydrochloride with excess of sodium hydroxide.
The oil which separated was extracted with ether, and the ethereal
solution dried, evaporated, and the residue fractionated under
diminished pressure, when a colourless, viscous oil, boiling at
177°/ 11 mm., was obtained. This oil crystallised after some hours

ON THE GLYCIDE AUYL ETHERS. PART I. 1S05

as a mass of plates. The crystals, after washing with a little dry
ether, softened at 53°, and melted at 58 — 60° :

0-2107 gave 0-5140 CO., and 0-1592 HoO. C = 66-53; H = 8-47.
0-0860 „ 5-9 c.c. N.3 (moist) at 21° and 753 mm. N = 7-74.
CjoHigOoN requires"^C = 66-24; H = 8-36; N = 7-73 per cent.

fi-Amino-^'-o-foli/loai/isojjrojJi/l alcohol dissolves moderately easily
in cold water, giving a solution with a strongly alkaline reaction
to litmus. It is readily soluble in alcohol, and rather less so in
ether. The solid base deliquesces rapidly in moist air, and absorbs
carbon dioxide readily.

The flatinichloride separates in yellow needles on adding platinic
chloride to a concentrated aqueous solution of the hydrochloride.
It melts and decomposes at 203° :

0-3060 gave 0-0760 Pt. Pt = 24-84.

(CioHi,,0.,N)o,HoPtCl6 requires Pt- 25-25 per cent.

The oxalate, (CioHj502N)2,H2C204, is obtained as a crystalline
precipitate on adding a solution of ammonium oxalate to a con-
centrated aqueous solution of the hydrochloride. On recrystal-
lisation from hot dilute alcohol, it forms shining leaflets, which
decompose rapidly at 200° :

0-1960 gave 11-2 c.c. Ng (moist) at 21° and 744 mm. N = 6-36.
^22-^32^8^2 requires N — 619 per cent.

The henzoate, CjoHj502N,C7H602, separates as an oil, which soon
becomes crystalline, on mixing aqueous solutions of equivalent
proportions of the hydrochloride and sodium benzoate. On re-
crystallisation from moist ethyl acetate, it forms clusters of prismatic
crystals, which soften at 131° and melt at 132 — 133°:

01940 gave 7-8 c.c. Ng (moist) at 20° and 743 mm. N = 4-50.
CiyHojO^N requires N = 4-62 per cent.

The benzoyl derivative, CioHi302'NHBz, prepared by the
Schotten-Baumann method and crystallised from ethyl acetate,
formed prismatic needles, melting at 114-5 — 115-5°:

0-2346 gave 11 c.c. No (moist) at 20° and 743 mm. N = 5-24.
CJ7H19O3N requires N — 4-91 per cent.

Dihydroxydi-o-tolyloxydi'pro'pylamine, (CioHi302)2NH.

The mixture of secondary and tertiary bases obtained as above
described was treated with cold ether. A portion remained un-
dissolved, and was collected, washed with ether, and crystallised
from hot ethyl acetate. On recrystallisation from the same solvent,
it formed rosettes of needles, melting at 117-5°:

1806 ACTION OF AMMONIA ON THE GLYCIDE ARYL ETHERS.

0-1120 gave 02856 COg and 0-0776 HoO. C = 69-54; H = 7-77.

0-2911 „ 10-5 c.c. N., (moist) at 17° and 751 mm. N = 4-14.
C00H27O4N requires C = 69-51; H = 7-90; N = 4-06 per cent.

The base dissolves readily in alcohol, giving a solution -with an
alkaline reaction. It is insoluble in water, and only very sparingly
soluble in cold ether.

Trihydroxytri-o-tolyloxytripropylamine, (CjoHj302)3N.

On evaporation of the ethereal solution, which has been filtered
from the insoluble secondary base, the tertiary base is left. It can also
be prepared by keeping glycide o-tolyl ether for some days in contact
with concentrated aqueous ammonia. The glycide ether changes
gradually into a cake of white crystals, consisting chiefly of the
tertiary base. It was recrystallised by dissolving in ethyl alcohol,
adding a little water to the hot solution, and allowing to cool
slowly. It separated in clusters of leaflets, melting at 83 — 84° :

0-2095 gave 0-5409 CO2 and 01484 HgO. C = 70-41; H = 7-94.

0-4803 „ 12-2 c.c. No (moist) at 19-5° and 751 mm. N = 2-84.
CsoHgrjOgN requires C = 70-67; 11 = 7-73; N = 2-75 per cent.

The base dissolves readily in alcohol or ether. The alcoholic
solution is neutral to litmus.

The hydrochloride is obtained on adding concentrated hydro-
chloric acid to a hot alcoholic solution of the base. The salt
deposits, on cooling, in crystals, melting at 134 — 135°:

0-3180 gave 0-0804 AgCl. CI = 6-26.

C3oH390gN,HCl requires CI = 6-48 per cent.

The 'platinichloride is obtained on adding platinic chloride to a
warm concentrated solution of the hydrochloride in alcohol con-
taining hydrochloric acid. It melts at 141°:

0-3602 gave 00497 Pt. Pt = 13-79.

(C3oH3905N)2,H2PtCl(j requires Pt = 13-65 per cent.

Trihydroxytri-o-tolyloxytripropylamine Oxide, (CjoHi302)3N!0.

This substance was prepared by adding to a solution of one gram
of trihydroxytri-o-tolyloxytripropylamine in 10 c.c. of glacial acetic
acid about 5 c.c. of 30 per cent, hydrogen peroxide, and warming
on a water-bath for about half an hour at 70 — 80°.

The mixture was then cooled and poured into water. Excess of
sodium hydroxide was added, and the whole shaken with ether.
From the ethereal solution so obtained, crystals of the oxide
separated almost immediately. After washing with ether, the

DIARYL ETHERS OF GLYCEROL. 1807

substance was dissolved in hot benzene, from wliich, on cooling, it
separated in minute prisms.

After recrystallisation it melted at 151°:

0-1915 gave 0-4801 COg and 0-1268 HoO. C = 68-38; 11 = 7-42.

0-2878 „ 7-1 c.c. No (moist) at 8° and 739 mm. N = 2-89.
C30H39O7N requires^C^ 68-51; H = 7-50; N = 2-67 per cent.

Chemical Department,
Hartley Unia'^ersitt College.

CC. — The Action oj Potassium Hydroxide on Epi-
chlorohydrin in Presence of Monohydric Phenols.

By David Runciman Boyd and Ernest Robert Marle.

Under the above title, Zunino has recently published a paper
{Atti R. Accad. Lmcei, 1909, [v], 18, i, 254), in which certain of
the diaryl ethers of glycerol are described.

The author is apparently unaware of the fact that three of
the ethers which he describes were prepared some years ago, the
diphenyl ether, 0H-CH(CHo-0Ph)2, by Rossing {Ber., 1886, 19,
63) and Lindeman {Ber., 1891, 24, 2147), and the di-o-tolyl and
di-m-tolyl ethers by one of us (Boyd, Trans., 1903, 83, 1137 and
1139). This is the more extraordinary since the question of the
constitution of these substances was discussed by us less than a
year ago (Trans., 1908, 93, 838).

Moreover, the statements made by Zunino with regard to the
properties of these substances arc incorrect.

The diphenyl ether is described as a liquid boiling at 287 — 288°,
whereas it is really a crystalline solid melting at 81 — 82°, and
boiling, with considerable decomposition, at the ordinary pressure
at 343—345° (uncorr.).

The di-o-tolyl ether is described as a liquid boiling at 296°,
whilst, as a matter of fact, it is a solid melting at 36 — 37°, and
boiling at 226°/ 13 mm.

The di-772-tolyl ether is described as boiling at 253 — 254°, whilst
we have found it to boil at 232°/ 13 mm., and, with considerable
decomposition, at 363° under atmospheric pressure.

Two other ethers are described by Zunino, namely, a dithymyl
and a dicarvacryl ether, which have not hitherto been prepared.
The boiling points assigned to the compounds, however (for the
dithymyl ether 215°, for dicarvacryl ether 245°), appeared to us

1808 DIAKYL ETHERS OF GLYCEROL.

SO improbable that we thought it desirable to investigate the action
of epichlorohj'driu on thymol in the presence of alkalis.
As a result, we have obtained glycide thymyl ether,

o<'

2 ^ ^10-^^13

CH-CHo-0-C,JI

and glycerol dithymyl ether, OH-CH(CHo-0-CioHi3)2. The former
substance is an oil boiling at 158°/ 16 mm., and the latter is a
crystalline solid, melting at All — 42°, and boiling at 270°/ 28 mm.

In Zunino's paper, no reference is made to the fact that by the
action of epichlorohydrin on phenols in the presence of alkalis two
different products may be obtained, namely, (1) the glycide aryl

ether, 0< " ,,* ^ . and (2) the glycerol diaryl ether,

OH-CH(CH2-OR)2.

We were at first inclined to suppose that the substances obtained
by Zunino were really the glycide aryl ethers. However, a com-
parison of the boiling points recorded with those of the glycide
aryl ethers in question shows a wide discrepancy (40 — 50°), and
we can only account for his data by supposing that he was dealing
with mixtures of the two substances.

Experimental.

Glycerol Dithymyl Ether, OH-CH(CH2-0-CioHi3)2.

This substance was prepared by the method previously described
for the diphenyl ether (Trans., 1908, 93, 840). On pouring the
reaction mixture into water, an oil separated. This was extracted
with ether, and, after removal of the ether, fractionated under
diminished pressure. In this way, a colourless, dense, very viscous
oil was obtained, boiling at 270°/ 28 mm. On keeping, it solidified
to a crystalline mass, melting at 41| — 42°:

(1) 0-2306 gave 0-6580 COo and 0-1867 HoO. C = 77-82; H = 9-06.

(2) 0-1297 „ 0-3696 COg „ 0-1069 HaO. C-77-70; H = 9-22.

C23H32O3 requires C = 77-52; 11 = 898 per cent.

Thymyl Glycide Ether, o<9^*^^2-0-CioH:3-

Twenty grams of sodium hydroxide (2 mols.), 35 grams of
thymol (rather less than 1 mol.), and 23 grams of epichlorohydrin
(1 mol.) were used. The sodium hydroxide was dissolved in 100 c.c.
of water, and the thymol added. Epichlorohydrin dissolves com-
pletely in this solution, forming a slightly yellow liquid, from
which an oil separates on keeping, and rises to the surface. After

I

THE CONSTITUTION OF HYDHOXVAZO-COMPOUNDS. 1809

four days, the oil was separated, warmed for half an hour with
powdered sodium hydroxide on the water-bath, and then dissolved
in ether. The ethereal solution was washed with water, dried, and
the oil left after evaporation of the ether was fractionated under
diminished pressure. A colourless, fairly mobile oil, with a faint
odour, was obtained, which boiled at 158°/ 16 mm. The residue,
about half of the original oil, consisted mainly of glycerol dithymyl
ether :

(1) 0-2666 gave 0o7440CO2 and 0-2114 HoO. C = 76-10 ; H = 8-87.

(2)0-3069 „ 0-8528 COo „ 0-2403 HoO. C = 75-77; H = 8-77.
C13HJ8O2 requires C = 75-73; H = 8-74 per cent.

Chemical Department,
Hartley University College.

CCI. — The Constitution oj Hydroxyazo-comjpounds,

Part II.

By William Bradshaw Tuck.

In a previous communication (Trans., 1907, 91, 449) the results
of a spectroscopic examination of simple hydroxy-derivatives of
azobenzene were given, and the absorption curves obtained were
compared with those of azobenzene and p-benzoquinonebenzoyl-
phenylhydrazone. The 2>liydroxyazo-compounds, their ethers and
acyl derivatives, and the ethers of o-hydroxyazo-compounds showed
absorption curves very closely resembling the curve for azobenzene.
The only difference was that the persistence or depth of the band
in the colour region varied with the group attached to the azo-
benzene nucleus. The head of the colour band belonging to the
above-mentioned substances always appeared at 250 mm. of
i\^/ 10,000 solution. On the other hand, the colour band of the
o-hydroxyazo-compounds and their acyl derivatives always appeared
at about 25 mm. of iV/ 10,000 solution. Thus the absorption curves
could be divided into two classes, the one having the head of its
isorropesis band at ten times the dilution at which the colour band
of the second class appeared. Since the difference between benzene-
azophenol benzoate and the isomeric p-benzoquinonebenzoylphenyl-
hydrazone was of a similar nature, the conclusion was drawn that
the two types of absorption curves were characteristic of two
different constitutions, namely, the hydroxyazo- and the quinone-
hydrazone structures.

1810

TUCK: THE CONSTITUTION OF

This conclusion was criticised by Auwers (Annalen, 1908, 360,
11) and by C. Smith and Mitchell (Trans., 1908, 93, 842), both
of whom considered that the difference between the two sets of
curves was not sufficient to justify it. Both authors neglect the
fact that the ratio of the dilutions at which the colour bands of
any ortho-compound and its ether appear (roughly 1 : 10) is of
the same order as tliat obtained from the absorption curves of the

Fig, 1.
Oscillation frequencies,
18 2000 22 24 26 28 3000 32 34 36 38 4000 42

30

28

^

26

s

en

24

«

2'.'

52

20

■^

\\

\.\

y \

/

'\

\\

/

\

\

\

\

\

1

\^

■' V/

?-v

x"

'"» \

/'

/]

-^

'^

ti

•■\

\_,'

-'/

\,

V-

~"-

\-

^.

V

■\

^

2500

1000

500

250 ^
100 2

50

25

10

Full curve : a-Naphthaquinonephenylmethylhydrazone in alcohol.
Dotted ,, Benzeneazo-a-naphthol ,,

Dot and dash curve : Benzeneazo-a-naphthol ethyl ether ,,

isomeric benzeneazophenol benzoate and ^'"I'enzoquinonebenzoyl-
phenylhydrazone.

In order to obtain further evidence, the absorption spectra of
the benzeneazonaphthols were investigated. It seemed probable
that results of importance would be obtained, since MacPherson
(Amer. Chem. J., 1899, 22, 364) had described the preparation of
both a- and )8-naphthaquinonephenylmethylhydrazone. The latter
compound would give definitely the curve for a hydrazone of an
o-quinone. MacPherson obtained the substance by the action of
phenylmethylhydrazine on )3-naphthaquinone in fairly dilute solu-

HYDROXYAZO-COMPOUNDS. PART II.

1811

tion, in a 2 per cent, yield. Unfortunately, I was unable to
prepare the substance by the method given, and a series of attempts
to obtain it all resulted in failure.

The substances of this group which were examined were
a-naphthaquinonephenylmethylhydrazone, benzeneazo-a-naphthol,
its ether and acetyl compound, bcnzeneazo-jS-naphthol and its
acetate, and )8-naphthaquinonephenylhydrazone and its acetyl
derivative. The curves are given in Figs. 1, 2, 3, and 4.

The absorption spectra of these compounds show no relation to

Fig. 2.

Oscillation frequencies.
18 2000 22 24 26 28 3000 32 34 36 38 4000 42

•^

)

I

'^

J

r^

(

/

V

/

A

l\

«

k

•

t

•

^TT-

^

J

1

<

•

s

*

J

2500

1000

**

o

o

f>()()

o

o

250

12;

'>>

1(10

"i^

tf

►V

50

^

%>

<^

25

-S

10

Full curve : Benzeneazo-a-naphthol in alcoholic sodium ethoxide.
Dotted ,, Benzeneazo-a-naphthyl acetate in alcohol.

that of azobenzene, or to those of previously recorded hydroxyazo-
compounds. This was quite unexpected, and no reason for it could
be seen from previous work. When, however, as will be described
later, the effect of various substituting groups on azobenzene was
studied, the explanation was obtained.

An examination of Fig. 1 shows that a-naphthaquinonephenyl-
hydrazone and benzeneazo-o-naphthol ethyl ether, although having
different constitu.tions, exhibit absorption spectra which are so
nearly alike that it is not obvious to which class benzeneazo-

1S12

TUCK : THE CONSTITUTION OF

a-uaplitliol itself belongs. Since, therefore, the problem is not
easy in the case of the para-compounds, the ortho-compounds could,

Fig. 3.

Full curve : Benzencazo-fi-naphtliol in alcohol.

Dotted ,, ,, ,, alcoholic sodium ctlioxide.

Dot and dash curve : Bcnzeneazo-fi-naphthyl acetate in alcohol.

Oscillation frequencies.

18 2000 22 24 26 28 3000 32 34 36 38 4000 42

250

100

50

25

10

250

100

50

25

10

'^

\\

2b

'■

\ \

[ ri

24

K

\/

\

22

V \

\

/"»

1 0

-

\

^* *

^-

1 fi

//

/

N

\

N

^,

■

1 1

r

....

^

\.>

K-^

\.

1"

^

%

n\

\

10

-\

op

\

OA

i

\

A

'>2

\

1

\

'>0

'

\/

\

18

A.

16

/

^

\^

^

I

,'

-.,

11

\

':

■

\\

V

/

«->.

I

T>

k^

-

A

/

\^

>

\

10

t'

^'v\ .

1

■

1

^

Fig. 4.

Full curve : fi-NaphthaquinonephrMijlhydrazonc in alcohol.

Dotted ,, ,, ,, alcoholic sodium cthoxide.

Dot and dash curve : Acetyl- fi-naphihaquinonephenylhydrazone in alcohol.

still less, be expected t-o yield results of value, as the absorption
curve for the o-quinonehydrazone form cannot be obtained.

A fresh line of research was then undertaken, and compounds
were examined which contained a hydroxy- or methoxy-group in

HYDROXYAZO-COMPOUNDS. PART 11.

1813

the ortho-position with respect to a group containing a double
bond similarly situated to that in benzeneazo-/;-cresetole (1) :

Me

(I.) c,h,-n:n<;^ y

(II.)

>ch:o,

UMo

OH

Fig. 5.

Full curve : Salicylaldehydc in alcohol.

Dotted ,, ,, ,, rtfco/toZ/c NiiOEt.

Dot and dash curve : o-Methoxybenzaldekyda in alcohol.

Oscillation frequencies.

18 2000 22 24 26 28 3000 32 34 36 38 4000 42

Fig. 6.

Full curve : Salicylaldehydephenylmcthylhydrazonc in alcohol.

Dotted „ ,, " ,, alcoholic NaOEt.

Dot and dash curve : o-Melhoxybenzaldehydephenylmethylhydrazone in alcohol.

The substances used were salicyl ildehyrle (IT) and its methvl
ether, and the phenylmethylhydrazones of both compounds.
VOL. XCV. (J u

18U

TUCK : THE CONSTITUTION OF

For comparison, the corresponding derivatives of jj-liydroxybenz-
aldehyde were examined. The phenylmethylhydrazones were used
in preference to the phenylhydrazones, since many of the latter

Fig. 7.

Full curve : ■^•Hydroxyhenzaldehyde in alcohol.

Dotted ,, ,, ,, alcoholic '^a.O'E.i,

Dot aud dash curve : Anisaldehyde in alcohol.

Oscillation frequencies.

18 2000 22 24 26 28 3000 32 34 36 38 4000 42

;2;

1

26

\

\

I

i\

,'

\

L

on

\\

t

'

V

\

18

\

\

1
1

!

1 f^

\

//

\

i

1

J

/

I

T>

1

1

' \

k

:^

."'

u-

V

20

oo

\

'>()

1 \
> \

\

18

1
1

\\

/

ifi

1

[\\

/

\

\

1 i

\ \\

/

' 1

1

I

12

\ \

\

/

/ ^

11

\

^l.

10

\

C

'^

■y

250

100

50 I

25 I
o
o

o

10 g-

CO

to

s
250 ;!

100 I

50

10

Fig. 8.

Full curve : ]i-Hydroxyhenzaldehydephenylinclhylhydrazone in alcohol.

Dotted ,, ,, ,, alcoholic NaOEt.

Dot and dash curve : Anisaldehydephcnylmethylhydrazone in alcohol.

undergo isomeric change (Baly and Tuck, Trans., 1906, 89, 892).
The curves are given in Figs. 5, 6, 7, and 8. In every case the
corresponding hydroxy- and methoxy-compounds show absorption

HYDROXYAZO-COMPOUNDS. PART II. 1815

spectra wLicli are practically identical. This is in agreement with
the observations in the case of 2>hydroxyazo-conipounds and their
ethers. When the close relation between these hydroxy- and
methoxy-corapounds is compared with the enormous difference
between an o-hydroxyazo-compound and its ether, it is obvious that
the two latter compouuds cannot have the same constitution,
or, in other words, the parent substance must be a quinone-
hydrazone.

The influence of sodium ethoxide on the absorption spectra of
this compound has also been studied, and very considerable light is
thrown by this means on the constitution of substituted azo-
compounds. In every case the characteristic band of the hydroxy-
compound is shifted towards the red, and as the band is unaltered
in shape it is extremely improbable that this denotes a change of
constitution. This shift towards the red end of the spectrum has
been observed in the case of phenol itself (Baly and Ewbank,
Trans., 1905, 87, 1347). Reference to the absorption curves
(Figs. 5 and 7) shows that in the case of ^j-hydroxybenzaldehyde,
sodium ethoxide causes the band to shift almost to the edge of the
visible region. In the case of salicylaldehyde, the shift is still
greater; the absorption band is now in the blue region, the sub-
stance being therefore yellow in colour.

It has already been shown that the difference between the
absorption spectra of the o-hydroxyazo-compounds and their ethers
is practically the same as that between the curves obtained for a
2?-hydroxyazo-compound and the isomeric quinonehydrazone (Tuck,
loc. cit.), and in the present paper it is shown that they are
different from all other hydroxy-compounds in that the absorption
spectra of their ethers are considerably different from those of the
parent compounds.

An effort was then made to obtain a substance which, whilst
undoubtedly an azo-compound, would show an absorption curve
similar to those of o-hydroxyazo-compounds and their acyl
derivatives. It was shown in a previous paper (Tuck, loc. cit.)
that the colour band of azobenzene was modified by substituting
groups, in a similar manner to the effect produced by the same
groups on the absorption spectrum of benzene. Thus, it was shown
that an acetoxy-group caused a smaller change than a hydroxy-
group, that is, the group with the smaller residual affinity
produced less change than one of greater residual affinity.

Although no group could be found which produced an absorption
spectrum similar to that of the o-hydroxyazo-compounds, still the
work resulted in the discovery of a reason for the isorropesis bands
of the sodium salts of the p-hydroxyazo-compounds, and for the

6 D 2

1816

TUCK : THE CONSTITUTION OP

difiference between the absorption spectra of benzeneazo-a-naphthol,
together with its derivatives, and azobenzene.

lu benzeneazophenol, the absorption spectrum consists of a " step
out " or limit of an absorption band in the visible region, with

Fig. 9.

Full curve : Azophenetole in alcohol.

Dotted ,, ,, ,, alcoholic NaOEt.

Dot aud dash curve : ^-Methoxybcnzeneazophcnol in alcohol.

Oscillalion frequencies.
18 2000 22 24 26 28 3000 32 34 36 38 4000 42

250

100

50

25

10

250

100

50

25

10

"k.

'^

1

24

I

\

^

^n

^

\

/

••x

\

18

1
I

\

/
/

\

/J

\

16

1

\ 1

/
r

y

Y'

\

1 ^

\

\'

/^

\

\

T^

/\\

^

■x^N

I

in

V

* • -

/

x^\

\

A

26

94

\

\

OO

v

A

^0

\

/

-,^

J

^

18

\

>

/

>

\

16

\/

/

X

\

1 1

\

/

/

^x

A

JO

^.

1
f

Vj

y

10

■l

Fig. 10.

Full curve : Azophenol in alcohol.

Dotted ,, ,, ,, alcoholic NaOEt.

a large band in the ultraviolet. If the curve for azophenetole
(Fig. 9) is examined, it is seen that the general appearance of the
curve is that of benzeneazophenol, but the sudden extension in the
visible region is slightly smaller, and also the ultraviolet band has

HYDROXYAZO-COMPOUNDS. PART II. 1817

shifted towards the red end of the spectrum. In ^^-methoxy-
benzeneazophenol, this phenomenon is slightly more marked, and
in azophenol the alteration is still greater. Thus, since the residual
affinity of a hydroxy! group is slightly greater than that of an
ethoxy-group, the residual affinity is increased progressively when
passing along the series, benzeneazophenol, azophenetole, jj-methoxy-
benzeneazophenol, and azophenol. Tlie change of absorption is
proportional to the residual affinity attached to the azobenzcnc
nucleus.

If now we turn to the absorption spectra of amino- and dimcthyl-
amino-azobenzene, we find that, whilst they are practically identical,
the colour band of azobenzene has disappeared, and the ultraviolet
band has been shifted right into the visible region. The band in
these two compounds is the same as that which the sodium salts of
j;-hydroxyazo-compounds also show. This means that the effect of
the substitution of an amino-group in azobenzene is identical with
that produced by the substitution of an 'ONa-group. From this
we may conclude that so far as their effective residual affinity
is concerned, the amino- and 'ONa-groups are identical. This is
confirmed by a reference to the absorption curves of aniline (Baly
and Collie, Trans., 1905, 87, 1332) and sodium phenoxide (Baly
and Ewbank, loc. cit.), which show absorption bands that are
exactly the same. Now, Baly and Ewbank showed that the charac-
teristic band of phenol was shifted towards the red by the addition
of sodium ethoxide. In the earlier part of this paper, it is shown
that an unsaturated grovip, namely, an aldehydic group, attached
to a phenol nucleus produces a similar effect. Thus 2>-hydroxy-
benzaldehyde exhibits the phenol band considerably shifted towards
the red end of the spectrum. This shift can be accentuated by
the addition of sodium ethoxide. This renders it probable that
the bands of aminoazobenzene and the sodium salt of benzeneazo-
phenol are merely those of aniline and sodium phenoxide respec-
tively, shifted into the visible region by conjugation with the
unsaturated group, 'NiN'C,;!!-. Since the absorption spectra of
aniline and sodium phenoxide are identical, the bands of amino-
azobenzene and the sodium salt of benzeneazophenol are the same.

In acetanilide, the effect of the acetyl group on the absorption
spectrum of aniline is entirely to change its character, probably
owing to the residual affinity of the nitrogen atom being conjugated
with that of the acetyl group. If, then, the hypothesis as regards
the absorption spectrum of aminoazobenzene is correct, then acetyl-
aminoazobenzene should show a type of absorption closely related
to that of azobenzene. A reference to the curve, Fig. 11, shows
that this is bo.

1818

THE CONSTITUTION OF HYDROXYAZO-COMPOtTNDS.

From the ciirves given, it is seen that the absorption spectra of
azo-conipoiinds show a gradual change from that of azobenzene
itself, the amount of change being proportional to the residual
affinity attached to the azo-nucleus. The limit of change is
apparently reached in the case of aminoazobenzene, since the
absorption spectrum of 2>aminobenzeneazophenol (Hewitt, Trans.,
1908, 95, 1292) is practically identical with that of aminoazo-
benzene.

Benzeneazo-o-naphthol is a compound which shows the same type
of absorption spectrum as aminoazobenzene, the band in the visible
region being the a-naphthol band shifted towards the longer wave-
lengths by conjugation with the group 'NIN-CgHg.

Fig. 11.

Oscillation frequencies.
18 2000 22 24 26 28 3000 32 34 36 38 4000 42

"^^

■"^

1

1

!

t

/

'X

7\

\

\

//

/

\

\

/'"

/

/ ^

\

\

\\

/

7

/

\~

\

\

/'/

\

/

»

I

^

^

\

250

100

50

25

10

Full curve : Amiv.oazohenzcne m alcohol.

Dottud ,, Acetylaminoazohenzene in alcohol.

Dot and dash curve : Dimethylaminoazohcnzcne in alcohol.

The absorption spectra of compounds known to be azo-compounds
fall between the extreme limits shown in the case of azobenzene
and aminoazobenzene. It has been pointed out that by suitably
substituting groups in the azobenzene nucleus, absorption spectra
anywhere between these limits can be obtained. The absorption
spectra of o-hydroxyazo-compounds cannot be obtained in this way,
and the fact that they do not fall between the two limits found
renders it extremely improbable that these ortho-compounds are
really derivatives of azobenzene.

In conclusion, the results obtained show that, whilst in general
the curves for o-hydroxy-compounds and their ethers are practically

GARDNER AND HODGSON: THE lODINATlON OF PHENOLS. 1819

identical, those of the so-called o-hydroxyazo-compounds and their
ethers are comparatively widely diflcrent. Again, the curves for
the parent o-hydroxyazo-compounds do not show absorption spectra
within the limits obtained for undoubted azo-compounds. These
results, together with the resemblance between o-hydroxyazo-com-
pounds and ;;-benzoquinonebcnzoylphenylhydrazone, lead to the
conclusion that the ortho-compounds are really quinonehydrazones.

Spectroscopic LABouATorvY.

Univeusity College, London.

ecu. — The lodination of Phenols and the lodometric
Estimation of, and Action of Reducing Agents on,
Tannic Acid.

By Walter M. Gardner, M.Sc, and Herbert H. Hodgson,
M.A., B.Sc., Ph.D.

The chief object of the work described in this paper * was to devise
a rapid quantitative and absolvite method for the estimation of
tannic and gallic acids.

Action of Reducing Agents on Tannic and Gallic Acids.

From the known, constitution of gallic acid, and from the formulae
ascribed to tannic acid, a quantitative yield of benzoic acid might
be expected on reduction. Bottinger (Annalen, 1890, 258, 252),
acting with metallic sodium on a solution of tannic or gallic acid
in absolute alcohol, obtained no reduction product, but Guignet
(Compt. rend., 1891, 113, 130) found that both tannic and gallic
acids yield benzoic acid when treated with zinc dust in acid or
alkaline solution.

After repeating these experiments, tannic acid was submitted to
the action of reducing agents under various conditions, and it was
found that, whilst little or no reaction takes place in neutral or
acid solution, tannic acid is very reactive towards alkaline reducing
agents. In no case, however, was a quantitative yield of benzoic
acid obtained, this being due to the fact that benzoic acid itself
is slowly destroyed by alkaline reducing agents. No higher yield
of benzoic acid was obtained by carrying out the process in an

* This paper corresponds with the abstracts " The action of reducing agents on
tannic and gallic acids" and "The action of iodine on phenols and a modified
process for the estimation of tannic acid" (Proc, 1908, 24, 272, 273),

1S20 GARDNER AXD HODOSON : THE lODINATION OF PHENOLS.

atmosphere of hydrogen or carbon dioxide, and in all cases the
complete reduction of tannic and gallic acids occupied a con-
siderable time.

I. — It educing Action of Zlnr.

Zinc and Ammonia (Guignet's process). — To 2'5 grams of zinc
dust in hot aqueous ammonia was added, with constant shaking,
1 gram of tannic acid dissolved in warm water. After boiling
under a reflux condenser for three hours, tannic aiid gallic acids
were absent. Potassium carbonate was then added, the solution
boiled to convert the excess of zinc and ammonia into carbonates,
then evaporated to dryness and extracted w:ith absolute alcohol.
On evaporation, 0"2 gram of pure potassium b^snzoate was obtained.

With zinc and ammonium chloride, 1 gram of tannic acid gave
0"13 gram of potassium benzoate, whilst zinc -vfith acetic, sulphuric,
or hydrochloric acid gave incomplete reduction even after many
hours' heating.

With zinc-copjDer couple, thirteen hours were required for
complete conversion, the amount of potassium benzoate obtained
from 0'5 gram of tannic acid being 0"14 gram.

Action of Zinc and Ammonia on Benzoic Acid. — One gram of
benzoic acid was heated under a reflux condenser for one hour with
2'5 grams of zinc in aqueous ammonia solution. The yield of
potassium benzoate was 0"69 gram, an amount which diminished
on further heating, thus demonstrating the slow destruction of
benzoic acid under the conditions employed.

II. — Reducing Action of Sodium.

Sodium and Absolute Alcohol (Bbttinger's process). — Two grams
of sodium and 1 gram of tannic acid were separately dissolved in
absolute alcohol. After heating the mixed solutions for two and
a-half hours, no benzoic acid was found, but 0"23 gram of gallic
acid was obtained.

Sodium and Moist Ether. — In this case no reduction took place,
but gallic acid was formed by hydrolysis.

III. — Beducing Action of Magnesium.

Magnesium and Hydrochloric Acid. — One gram of tannic acid
gave 0'25 gram of gallic acid, but no benzoic acid.

Magnesium and Ammonium Chloride. — In this case the reaction
was very violent, and amounts of potassium benzoate, varying from
0'08 to 0"23 gram, were obtained from 0"5 gram of tannic acid.

Magnesium and Potassium Carhonate. — Hero the reaction was
moderate, and after heating for five hours on the water-bath the

OARDXEU AXD HODGSON: 'IHE loDIN' A'l'IoX OF PHENOLS. 1821

yield of potassium bcuzoate was 0'2 gram from 0"5 gram of tannic
acid.

Magnesium Powder. — In the above cxjDeriment, when magnesium
powder was added to the hot solution of tannic acid, a slight action
was observed, and therefore the effect of magnesium powder alone
was tried. On heating for several hours on the water-bath in a
neutral atmosphere, 05 gram of tannic acid gave 0'08 gram of
potassium benzoate.

IV. — By reaction with aluminium powder and potassium
hydroxide, sodium hyposulphite, or hydriodic acid, no formation of
benzoic acid occurred.

It is thus seen that in a number of the above experiments the
production of benzoic acid was demonstrated, but in no case were
the results of quantitative importance, and, although the conditions
of concentration, time of reaction, and nature of atmosphere, were
widely varied, the results were always unsatisfactory. One general
observation was, however, of interest, namely, the tendency of
tannic and gallic acids to form reduction products vmder alkaline
conditions, and this is further borne out by experiments made
with alkali iodides, which have given much more satisfactory
results.

The Action of Iodine on Fltenols.

Messinger and Vortmann have shown (Ber., 1890, 23, 2753)
that phenol absorbs iodine in the presence of alkali hydroxides,
but were unable to obtain satisfactory quantitative results.

F. Musset {Chem. Neics, 1885, 51, 42) has described a method
of titrating tannin with iodine, but the absorption required twelve
hours. The " non-tannins " were estimated in a second experiment
after precipitating the tannic acid by means of gelatin.

A. Moullade (/. Pharm. Chim., 1905, [vi], 22, 153), who titrated
tannic acid with iodine in presence of sodium hydrogen carbonate,
using carbon disulphide as indicator, states that it is necessary to
take the mean of several titrations in order to ensure accuracy, and
estimates the non-tannins in the usual manner. All the above-
mentioned methods are thus defective, Musset's process requiring
at least twelve hours, and that of Moullade being deficient in
accuracy.

The modified method which the authors propose, apart from
the gelatin precipitation, can be carried out in a few minutes, and
concordant results are obtained, not only with tannic acid, but
with many other phenolic substances. Within the range of
phenols dealt with, a number were found to require one molecule

1S22 GARDNER AND HODGSON: THE lODINATlON OF PHENOLS.

of iodine for each Iiydroxyl groxip. whereas in other cases, although
the results were strictl}' quantitative, they were empirical in the
sense that no ratio could be traced between the iodine absorbed
and the number of hydroxyl groups.

The general method is as follows. A standard aqueous solution
of the phenol is prepared (in the case of tannic acid 1 gram per
litre), and to a known volume of this solution (20 c.c, diluted to
200 c.c. with water) iV^/10-iodine solution is added in excess
(20 c.c). A few drops of starch solution are then added, and
afterwards aqueous sodium hydroxide is run in drop by drop
until the colour due to the iodine disappears. By this means,
excess of alkali, which has an injurious effect on the accuracy of
the process, is avoided. Dilute hydrochloric or sulphuric acid
(1 in 4) is added in sufficient excess (say 50 c.c.) to separate the
unabsorbed iodine, the amount of which is estimated by iV/10-
thiosulphate.

In the case of phenol, catechol, quinol, pyrogallol, and gallic
acid, the amount of iodine absorbed is exactly one molecule for each
hydroxyl gi'oup present.

The presence of such groups as NOo, NHo, or OMe, as well as
the position of the hydroxyl groups in the benzene nucleus, was
found to have a determining effect on the course of the reaction.
For example, the weak phenolic properties of the hydroxyl groups
in ;p-h3^droxybenzoic acid result in there being no absorption of
iodine.. The presence of nitro- or methoxy-groups also protects the
hydroxyl group from attack, while in j;-aminophenol a definite
quantitative absorption was observed, which, however, did not
correspond with one hydroxyl group. The alcoholic hydroxyl
group, for example, in benzyl alcohol, is also unaffected under the
conditions of the process.

Phloroglucinol, which possesses both phenolic and quinonoid
properties, gave an absorption equivalent to two hydroxyl groups,
whereas the isomeric pyrogallol behaved normally, the three
hydroxyl groups absorbing three molecules of iodine. A similar
normal result is obtained with gallic acid.

In the case of gallotannic acid, a large number of experiments
were made under varying conditions of concentration, amount of
excess of iodine, etc., and perfectly concordant results were always
obtained. The process is, therefore, available for the quantitative
estimation of gallotannic acid, and is applicable to the commercial
tannins. Two estimations are, of course, necessary. First, that
of the total iodine absorbed by the standard solution of the
tannin, and, secondly, that of the iodine absorbed after removing
the tannic acid from the solution by precipitation with gelatin or

GARDNER AND HODGSON : THE lODlNATION OF PHENOLS. 1823

absorption by bide powdor, tbe difTeience in tbc two estimations
giving tbc iodine absorbed by tbe tannic acid itself.

In the case of pure tannic acid, tbe absorption was found to
correspond with 11 atoms of iodine for each molecule of tannic
acid. On the supposition that tannic acid may be regarded as
digallic acid,

OH ,0H OH

0H<^ ^C0-0<^ \

0H~ CO2H

it may be assumed that the chain connecting the benzene nuclei
is responsible for the absorption of tbe additional atom of iodine, the
molecule undergoing fission at the chain and forming two molecules
of sodium gallate, in one of which an OH group is replaced by 01.
The works of Wys {Zed.^rh. angew. Chem., 1898, 11, 291),
Koene (Fogg. Ann., 1845, 66, 302), and others on the action of
Hiibl's solution is interesting in connexion with the above recorded
observations. Wys attribvites the absorption of iodine by un-
saturated fatty acids to the presence of iodine monochloride :

HgC1.3 + 4I = Hgl2 + 2ICl,

which reacts with water, yielding hypoiodous and hydrochloric acids.
The hypoiodous acid is slowly transformed into iodic acid and free
iodine, the latter again forming iodine monochloride by reacting
w'th the liberated hydrochloric acid. A complicated equilibrium
is thus established, the really active substances being contained
in the cycle, iodine-iodine chloride-bypoiodous acid.

Koene (Joe. cit.) has shown that correct iodine values are rapidly
obtained by means of the solution produced by shaking alcoholic
iodine with finely divided mercuric oxide, which solution contains
only mercuric iodide and hypoiodous acid, and Wys has further
shown that in the presence of any substance favourable to the
formation of hypoiodous acid, for example, iodine, mercuric chloride,
or water, iodine absorption takes place more rapidly, whereas the
presence of hydrochloric acid or mercuric iodide, which retard the
production of hypoiodous acid, have an opposite eflfect.

The very rapid absorption of iodine in presence of alkali, which
occurs in the method for the estimation of phenols suggested in
this paper, is very probably due to the formation of hypoiodates.

The action of Hiibl's solution on tannic acid has been studied
with the view of throwing further light on the question, and a
direct connexion between the iodine absorbed from Hiibl's solution
and that taken up from an alkaline solution has been established.
Attempts were also made to isolate iodotannin compounds, but
without success. Similar lack of success in this direction has been

lS-2-i GARDNER AND HODGSON: THE lODINATlOX OF PHENOLS.

recorded by F. B. Power and F. Shedden {rharm. J., 1901, [iv],
13, 147). These authors consider that true compounds of tannic
or gallic acid with iodine cannot be formed by the simple inter-
action of these compounds in the presence of water, the resulting
products containing the iodine in the form of hydriodic acid
associated with more or less unaltered tannic or gallic acid and
their oxidation products.

Comparison between the results obtained with the iodine process
and the Lowenthal method, when applied to a number of the
commercial tannin-containing materials, showed a close agreement
in all cases.

Experimental Results.

Phenol. — 0"1 Gram of phenol was dissolved in 100 c.c. of water.
To 10 c.c. of this solution, 5 c.c. of iV^/10-iodine were added, and
then a few drops of starch solution. Sodium hydroxide solution
was then cautiously added, drop by drop, vintil the solution became
colourless. After stirring, concentrated hydrochloric acid was
added, and the separated iodine estimated by standard thiosulphate.
The mean of six titrations gave 2' 15 c.c. of iodine solvition absorbed
( = 0'0273 gram of iodine). On the supposition that one hydroxyl
group requires one molecule of iodine, 0'0272 gram of iodine is
theoretically required.

Salicylic Acid. — O'Ol Gram of salicylic acid in aqueous solution
absorbed 1'85 c.c. (0"0234 gram) of iodine. Calculated for one
hydroxyl group, the theoretical absorption is 0"0184 gram of
iodine. The result in this case is, therefore, em23irical, although
repeated estimations proved it to be quantitative.

Messinger and Vortmann (loc. cit.), following Kopperschaar's
process for the estimation of phenol by bromine, proposed to
estimate salicylic acid by precipitating it in alkaline solution, as
sodium di-iodoiodososalicylate, by addition of iodine and titrating
the excess of iodine with sodium thiosulphate. W. Fresenius and
Griinhut {Ztit&ch. anal. C'hcm., 1899, 38, 292) have criticised this
method adversely, but in our experiments the results were remark-
ably consistent, and the results were unaffected by the concentration
of the solution or the amount of excess of iodine or of sodium
hydroxide. Moreover, the method is available for the estimation of
salicylic acid in the presence of benzoic acid.

Resorcinol. — O'Ol Gram of resorcinol absorbed 5"2 c.c. (0'06604
gram) of iodine. The theoretical amount of iodine representing
three molecules is 00694 gram.

Catechol.— 0- 01 Gram required SGo c.c. of i\V10-iodine (0-0461
gram). Theory for two hydroxyl groups — 00463 gram. In^ this
case, therefore, the reaction may be considered normal.

GARDNER AND HODGSON: THE lODINATlOX OF PHENOLS. 1825

Qiiinol. — 001 Gram required 36 c.c. of 3'/10-iodine (0"0456
gram). Theory requires 0"0,463 gram. Of the three isomeric di-
hydroxybenzenes, therefore, the ortho- and para-compounds behave
normally, whei'eas the meta-derivative gives somewhat empirical
results.

Pyrogallol. — 001 Gram required 61 c.c. of i\^/10-iodine, which
corresponds almost exactly with three hydroxy! groups on the
supposition that one molecule of iodine is required for each
hydroxyl group.

Gallic Acid. — 0"01 Gram required 3'55 c.c. of i\^/10-iodine (0"0448
gram). Theory for three hydroxyl groups = 0*0450 gram.

Catechu-tannic Acid. — O'Ol Gram in four titrations absorbed
3 c.c, 2'9 c.c, 3*1 c.c, and 2'9 c.c. respectively of iV/lO-iodine.
The method is, therefore, available in this case.

Catechin. — O'Ol Gram required 2'4 c.c of iY/10-iodine (0'033
gram). Calculation for five hydroxyl groups gives 0"035 gram of
iodine.

Influence of the Presence of other Growps on the Iodine Absorption.

Ortho- and para-nitrophenols do not absorb iodine under the
conditions, showing the protective action of the nitro-group.
Picric acid is also inactive. In the case of ^^-aminophenol, O'Ol
gram absorbed only 035 c.c. of iV/lO-iodine (0"00444 gram). This
corresponds with approximately one molecule of iodine for each four
molecules of jj-aminophenol. The result clearly shows the influence
of the amino-group, and the method in this and similar cases is
useless. Some absorption of iodine also takes place in the case
of anunonaphthol-4-sulphonic acid. The non-absorption of iodine by
mannitol, benzyl alcohol, and other compounds containing alcoholic
groups, shows that the method is not available in the case of
aliphatic hydroxyl groups. In the case of phloroglucinol, which
can behave either as a phenol or as a quinone, O'Ol gram absorbed
0'04318 gram of iodine, which closely corresponds with two instead
of the three hydroxyl groups actually present. The protective
action of the methoxy-group is indicated in the case of vanillin,
with which no absorption takes place. The influence of the position
of the hydroxyl group is well shown in the case of the hydroxy-
benzoic acids. No reaction takes place with the j7-derivative, but
with salicylic acid, as already noted, quantitative results were
obtained. This difference is probably associated with the pro-
nounced phenolic character of salicylic acid exhibited in its
antiseptic properties, its low melting point, its reaction with ferric
chloride, its ready solubility in chloroform, and its slight solubility

1S26 GARDNER AND HODGSON: THE lODINATION OF PHENOLS.

in water, in which properties it is iu marked contrast to its
isomerides.

Cinnamic Acid. — This unsaturated acid, which contains no
hydroxyl group, does not absorb iodine from alkaline solution.

Tannic Acid. — For the experiments with this substance, a sample
of pure tannic acid (Kahlbaum) was used. 0'02 Gram required,
as the mean of a large number of closely agreeing titrations,
7'15 CO. of iV/lO-iodine. After precipitating the tannic acid by
gelatin, an absorption of 0"3 c.c. of i\''/10-iodine was given by
20 c.c. of the residual solution. The corrected amount of iodine
absorbed was therefore =008698 gram. 002 Gram of tannic acid
requires for five hydroxyl groups 0"0788 gram of iodine (pl^), and
for six hydroxyl groups 0'0946 gram (Gig). On the supposition
that 11 atoms are absorbed by one molecule of gallotannic acid,
the amount of iodine required by 0'02 gram of gallotannic acid
is 0'0876 gram, which figure is in practical agreement with the
experiments. The purity of the tannic acid was, however, not
known.

In order to test the reliability of the method, a large
number of results were obtained, using widely differing quantities
of the substances. The method was also applied to a number of
the ordinary tannin-containing materials, the results obtained being
compared with those given by the Lowenthal process. The solution
of tannic acid contained 1 gram per litre :

Yolume of tannic acid solution, c.c. ... 40 35 30 25 20 15 10 5
iVVlO-iodine, c.c 14-25 12-45 1070 8-90 7-15 5-35 355 1-80

In each case the solution was diluted to 200 c.c. with water.
The experiments were repeated, using iV^/50-iodine and N/50-
sodium thiosulphate :

Volume of tannic acid solution, c.c 20 15 10 5

,, iV/50-iodine expressed as sodium thio-
sulphate, c.c 34-87 26-30 1753 8-76

Comparison of the Iodine with the Lowenthal Method. — The
results (p. 1827) are expressed in percentages of tannic acid,
Kahlbaum's pure tannic acid being taken as the standard.

Comparison of the Iodine Method ivith Hiihl's Process. — 0*2 Gram
of tannic acid was dissolved in 25 c.c. of alcohol, and 25 c.c. of chloro-
form, followed by 25 c.c. of Hiibl solution, were adJed. After
standing twenty-four hours, the iV/10-iodine absorbed was 33"55
c.c, the figures in sixteen experiments varying from 32"3o c.c. to
35-25 c.c A similar series, in which the chloroform was omitted,
gave 32'46 c.c. of N j\0-iodine absorbed. The amount taken up by
0"2 gram of tannic acid under alkaline conditions is 71 '5 c.c, of
iV'/lO-iodine, which is almost double the above figure.

REACTIVITY OF THE HALOGENS IN ORGANIC COMPOUNDS. 1827

Luweiith;il

Tannins. metliod.

Gall-nuts No. 1 Extract 66-47

No. 2 ,, 6402

No. 3 ,, 60-40

No. 4 ,, 63-61

No. 5 ,, 62-59

Sumac No. 1 Extract 22-84

No. 2 ,, 22-51

No. 3 ,, 16-57

No. 4 „ 17-20

Myi-abolams... No. 1 Extract 26-06

No. 2 , 27-52

No. 3 , 29-33

No. 4 , 31-24

Valonia 28-11

Dividivi 33-00

Quebracho 1363

lod

ine

methoJ

65

3

65

62

60

28

63

14

62

09

21

26

20

14

16

08

16

78

27

27

27

44

29

74

31

12

28

67

31

47

13

28

General Conclusions.

The absorption of iodine by phenols in alkaline solution appears,
in certain cases, to take place in definite molecular proportions,
but in other cases in empirical, although quantitative, amount.
The absorption takes place most readily in the case of compounds
with pronounced phenolic properties, and is, in some eases, entirely
prevented by the presence of other groups in the benzene nucleus.
The method described is, however, available for the quantitative
determination of tannic acid and other substances, and involves no
complicated or lengthy process or the observation of an indefinite
end-point. It appears, therefore, to be of practical importance.

Technical Research Laboratory,
Technical College,
Bradford.

CCIII. — Reactivity of the Halogens in Organic Com-
pounds. Fart III. Interaction of Bromoacetic,
a-Bromopropionic, and a-Bromohutyric Acids ayid
their Sodium Salts with Water and ivith Alkali.
By George Senter.

In previous papers (Trans., 1907, 91, 460; Proc, 1908, 24, 89;
Arrkenius Festschrift, 1909, Vol. II) the results of an experimental
investigation of the rate of displacement of the halogens in chloro-
acetates and bromoacetates have been given, aud the mechanism of

1828 SENTER : REACTIVITY OF THE HALOGENS IN

the respective reactions was discussed. Keasons have been adduced
for the opinion that in the hydrolytic decomposition of chloro- and
bromo-acetic acids by water, according to the equation :

CH2X-C0,H + IIjO = OII-CHg-COoH + HX
(X = C1 or Br), the reaction takes place mainly between the non-
ionised acid and non-ionised water. This view as to the mechanism of
these reactions is further discussed in the present paper in connexion
with the corresponding measurements with the higher and substituted
fatty acids.

The decomposition of the sodium salts of the halogenaeetic acids by
water and by alkali, represented by the general equations

CHaX-COgNa -f U^O = OH-CHg-COgH + NaX (1 )

and

CHgX-COaNa + NaOH = OH-CHa'COgNa + NaX (2),
appears to be rather complicated. The experimental results are mosb
readily accounted for on the view that in case (1) the main reaction
in dilute solution takes place between CHgX'COO'ions and non-ionised
water, but in more concentrated solutions the reaction of the sodium
salt, CHgX'COgNa, with water becomes of importance. For reactions
of type (2) the mechanism in dilute solution is represented by the
equation :

CH2X-C00' + OH' = OH-CHg-COO' + X',
but in moderately concentrated solutions the reaction

CH2X-C02Na + OH' = OH-CHg-CO^Na + X'
also comes into account.

The present paper deals with the displacement of the bromine in the
first three members of the series of a-bromo-fatty acids and their sodium
salts, the results obtained with bromoacetic acid having been partly
repeated for the sake of comparison. As the mechanism of the
reactions has already been discussed in connexion with the lowest
members of the series, it has not been considered necessary, in the
case of the higher acids, to vary the experimental conditions so widely,
and attention has mainly been directed to the influence of substitution
on the reactivity of the halogen. The results show that even in com-
pounds so similar in type as the a-bromo-fatty acids, there are remark-
able differences in the relative reactivity of the halogen according to
the method by which it is measured.

Experimental.

Hydrolytic Decomposition of the Bromo-fatty Acids hy Water. — The
results of a typical series of experiments with bromoacetic acid,
a-bromopropionic acid, and a-bromobutyric acid at 81° are given in

ORGANIC COMPOUNDS. PART III. 1829

table I. The acids were employed in approximately iV/10-solution ;
quantities of 10 c.c. were sealed up in small tubes of Jena glass, and
placed in a thermostat at constant temperature.- At intervals tubes
were taken out, rapidly cooled, and the contents titrated with a dilute
solution of barium hydroxide, using pheuolphthalein as indicator. In
the tables the concentrations, Ct, are given in c.c. of the barium
hydroxide solution required to neutralise the bromo-acid remaining in
10 CO. of the solution after heating for the time t. The " constants,"
k, are calculated according to the formula for a unimolecular
reaction, 0'4343/l-= l/tlog^f^OojCt, where 0,, is the initial concentration.

Table I. — Temperature 81°.

a-B

roiiK

pro-

o-Bromo-

Bromoacetic acid,

iV/10.

plOIllC

cacid

iV/10.

butyric

acid.

t (miu. ).

Of.

k.

Or.

^•.

Oc

k.

0

11-4

—

12-6

—

11-8

—

60

10-3

00017

10-2

0 0035

8-9

0-0043

150

9-1

0-001.5

8-5

0-0026

7-3

0 0032

270

77

0-0014

6-8

0-0023

6 0

0 0025

These results illustrate two important points : (1) the initial rate at
which the bromine is displaced increases somewhat with the com-
plexity of the acid ; (2) whilst the " constants " for bromoacetic acid
diminish slowly, those for the remaining acids diminish rapidly as the
reaction proceeds. As it seemed probable that this diminution in the
value of the constants might be connected with the presence of the
hydrobromic acid formed in the course of the reaction, several series
of experiments were made in the presence of different concentrations
of hydrobromic acid, added at the commencement of the reaction. The
results are given in the accompanying table.

Table II.
a-Bromopropionic Acid, N/10. — Temperature 79°.

No hydrobromin

acid.

O-lOiV-Hydro-
bioiiiic acid.

0-20iV^-Hydro.
bromic acid.

t. Ct.

k.

Ct.

k.

Ct.-

k.

0 11-8

11-8

—

11-8

—

120 8-8

0-0024

10-4

0-00105

10-8

0-00074

240 7-3

0-0020

9-4

0-00095

99

0-00074

360 6-3

0-0017

8-8

0-00082

9-1

0-00073

L380 2-2

00012

3-9

0-00080

4-6

0-00069

0-40.V-Hydrob

■0111 ic acid.

0-80iY-Hydi-obromic

acid.

t. Ct.

k.

t.

Ct.

k.

0 11-8

—

0

11-8

—

180 10-5

0-00065

240

10-4

0-00053

360 9-4

0 00064

1335

5-8

0-00053

1380 5-3

0-00061

VOL. XCV.

6 E

1830 SENTER: REACTIVITY OF THE HALOGENS IN

In another series of measurements at the same temperature, in the
presence of 0'27i\^-hyclrobromic acid, the value of k was 0'0068, in
good agreement with the above results.

The data just given show that in the absence of hydrobromic acid
the reaction is comparatively rapid, but as the acid accumulates in the
system, the rate rapidly diminishes. Further, in the presence of
0"20iV-hydrobromic acid, constants agreeing well for a unimolecular
reaction are obtained, and addition of more acid has comparatively
little effect on the reaction velocity. The bearing of these lesults on
the mechanism of the reaction is discussed in detail later (p. 1836).

As regards the effect of hydrobromic acid on the rate of decom-
position of bi'omobutyric acid by water, it will be .sufficient to quote
the result of one series of experiments.

Table III.
a-Bromohutyric Acid, N/10. — Temperature 79°.
No hydrobromic acid. 0-27iV-H\'drobromic acid.

t.

Co

k.

t.

Ct.

0

11-6

—

0

11-6

—

60

9-5

0-0033

150

10-9

(0-00042)

150

8-3

0-0022

360

10-3

0-00033

360

380

6-3
3-0

0-0017
0-0010

1380

7-2

0 00035

These results show that the rate of decomposition of bromobutyric
acid by water diminishes still more rapidly than that of bromo-
propionic acid, and, in agreement with this, that hydrobromic acid in
equivalent concentrations retards the former reaction still more than
the latter.

i\74-Hydrobromic acid reduces the constant for bromoacetic acid
from 0-0062 to 0-0057 at 102°.

Influence of Neutral Salts. — The effect of neutral salts on the rate
of hydrolysis of the bromo-fatty acids by water is very slight, as the
following results show. The constants are calculated from a rather
advanced stage of the reactions, when the value for bromobutyric acid
is less than that for bromopropionic acid.

Table IV. — Temperature 79°.
a-Bromopropionic acid, KjlO. a-Bromobutyric acid, iV^/10.

Salt added. k. Salt added. k.

No salt 0-0013 No salt 0-0010

+ J//1 -Sodium bromide.. 0-0012 -l-jl//l-Sodium bromide.. 00009

+ 3//1 -Sodium nitrate ... 0 0012 + 3//1 -Sodium nitrate ... 0-0010

ORGANIC COMPOUNDS. PART III. 1831

Reaction betiveen Sodium Salts and Water.

The sodium salts were prepared in dilate solution by careful
neutralisation of the acids with sodium hydroxide, free from
carbonate. The solutions, which were approximately ^7^^' were
heated for definite intervals in sealed tubes at constant temperature,
and the contents of the tubes titrated with barium hydroxide and
phenolphthalein. The concentrations, Ct, are expressed as the number
of c.c of the standard barium hydroxide solution which would be
required to neutralise the acid equivalent to the amount of salt in
10 c.c. of the solution after the time t has elapsed. The values of k
are calculated according to the integrated eqviation,

0-i3i3k^l/t\og,,C,/Ct,
for a unimolecular reaction.

Table V. — Temperature 52-4°.

Sodium o-broraopropionate,
Sodium bromoacetate, iV/10. approx. iS'/lO.

t (luiu. ).

C't.

t (miu.

).

c„

k.

0
1560
3120
4440

11-0
9-4

7-9
6-9

0-00010
000010
0-00010

0

60

120

240

12-4

11-4

10-7

9-5

0-0014
0-0012
0-0011

Sod

um o-bromobutyrate,

iV/10

t.

c,.

k.

0

60
120
240

10-9
9-3
8-5
7-3

0-0026
0-0023
0-0017

The table shows that sodium bromoacetate and sodium bromo-
propionate give fairly good constants for a reaction of the first order,
although in the latter case there is a slight diminution as the reaction
proceeds. In the case of sodium bromobutyrate the diminution in the
magnitude of the constants is still greater. As it seemed probable
that this might be due to the influence of the sodium bromide formed
in the course of the reaction, some measurements were made in the
presence of this salt, and the results are given in table VII.

As the results obtained with sodium chloroacetate described in the
previous paper appear to show that both the ions CH2C1'C00' and
the non-ionised sa,lt, CHgCl'COgNa, react with water, it was considered
desirable to make some comparative measurements with sodium bromo-
propionate and butyrate in Nl\^- and iV/1 00 -solution ; in the latter
dilution the salts are almost completely ionised. The results are sum-
marised in table VI, and show that the reactions are rather more
rapid in the more dilute solutions.

6 E 2

1832 SEXTER: REACTIVITY OF THE HALOGENS IN

Table VI. —Temperature 52-4°.

Sodium Sodium Sodium

liroinoiicctato. broiuopropionatp, bromobutyrate.

Dilution. k. Dilution. k. Dilution. k.

x/\o 0-00010 ivvio 00012 ivyio 00023

iV'/lOO 0-00010 A'/lOO 0-0014 -^/lOO 0 0026

The bearing of these important results on the mechanism of the
reaction is discussed later (p. 1837).

Influence of Neutral Salts, — As in the case of the free acids, the
effect of sodium bromide and of sodium nitrate on the reactions has
been investigated, with the following results :

Table VII.— Temperature 52-4°.
Sodium a-Bromopropionate, N/10.

No

salt added.

il//l -Sodium

bromide.

^//1-Sodi

im nitrate

t (min.).

Ct.

k.

c,.

k.

Ct.

k.

0

13-4

—

13-4

—

13-4

—

90

11-7

0-0015

12-2

0-0010

11-9

0-0014

330

8-6

00014

10-0

0-0009

8-9

00013

Sodium a-Bromobutyrate, N/10.

Nos

alt add

3d.

J//I-S0C

liuiu

bromide.

J//1-S

Ddium nitrat*

t (mill.).

Ct.

k.

Ct.

k.

Ct.

k.

C

n-7

—

11-7

—

11-7

—

90

9-4

0 0024

9-9

00019

9-6

0-0022

330

6-3

0-0020

7-8

00013

6-7

0-0017

These results indicate that, whilst the rate of the reactions is only
slightly diminished by the addition of sodium nitrate, both reactions
are considerably retarded by sodium bromide (compare p. 1838).

Reaction between Sodium Salts and Alkali.

The chemical changes in this case are expressed by the general
equation :

R-CHBr-COgNa + NaOH = R-CH(0H)-C02Na + NaBr,
where R represents hydrogen or an alkyl group. Dilute solutions of
the sodium salts were mixed with an equivalent amount of alkali, and,
after heating in sealed tubes for definite intervals, were titrated with
approximately ^^7lO-sulphu^ic acid and phenolphthaleiu. In all cases
the .sodium salt and the alkali were present in equivalent proportions,
and the concentrations are expressed as the number of c.c. of acid

ORGANIC COMPOUNDS. PART III. ]833

required to neutralise 10 c.c. of the reaction mixture. The vahies
of k for the broraoacetate are calculated according to the general
equation for a bimolecular reaction,

when the reacting substances are present in equivalent amounts.

Table VIII.

— Temperature 52

4°.

Sodium

Sod

iuiii

bromoaeetate

lironiopropionato

Sodium

hromobutvrate

and

liy

lroxid(

3, A'/lO.

and hydroxide

N/IQ

and hy(

[roxi(

e, AyiO.

t.

'c>'7~

k.

Q.

k.

Cr.

k.

0

11-8

—

13-6

—

11-6

60

8-5

0-000.5.5

11-8

—

9-6

180

5-5

0-00054

9-6

—

7-4

300

4-3

0 00050

7-9

—

6-2

—

The figures show that in the presence of sodium hydroxide, bromine
is displaced from sodium bromoaeetate more rapidly than from the
other two salts, and that for the former reaction constants agreeing
well for a bimolecular change are obtained. On comparing the
numbers found for sodium bromopropionate and bromobutyrate with
those obtained for the same salts with water alone, it will be seeu
that the speed in the latter case is not much less than when alkali is
present. Hence it is not justifiable to calculate the results on the
assumption that only the reaction between the salts and alkali is of
importance (as in the case of sodium bromoaeetate) ; we are deal in "•
with two simultaneous reactions, in which the salts are acted on by
water and by alkali. The calculation of the experimental results on
this basis is dealt with in a later part of the paper.

Influence of Neutral Salts. — In the former paper it was shown that
the rate of reaction between sodium bromoaeetate and sodium hydroxide
is greatly accelerated by the action of neutral salts. In the same
way the effect of neutral salts on the reaction between sodium
hydroxide and sodium bromopropionate and bromobutyrate respec-
tively has been investigated ; the results are given in table IX.

Table IX.— Temperature 52-4°.
Sodium Bromopropionate and Hydroxide, N/IO.

No neutral salt.

t.

Ct.

0

13-4

90

11-2

240

8-3

J//l-Sodium

^//1-S')dium

bromide.

nitrate.

Ct.

Ct.

13-4

13-4

11-2

11 -1

8-9

7-8

1834. SENTER: REACTIVITY OF THE HALOGENS IN

Table IX. — Temperature 52-4° (continued).
Sodium a-Bromohutyrate and Hydroxide, N/IO.
No neutral salt.

ilZ/l-Sodium
bromide.

il//l -Sodium
nitrate.

11-7

10-3

8-6

11-7
9-8 •
7-5

0 11-7

90 10-0

240 7-8

These results are rather difficult to interpret, as we are dealing
with two simultaneous reactions which are presumably differently
influenced by neutral salts.

Discussion of Results.

Reactivity of Bromine in the Different Compounds. — It will be of
interest before dealing with the individual reactions to represent in
tabular form the relative velocity with which bromine is displaced
from the three acids and their salts under equivalent conditions. The
measurements have not all been made at the same temperature, but by
means of the temperature-coefficients given in the previous paper
(Arrhenius Festschrift, loc. cit.), and on the provisional assumption
that the coefficients for reactions of the same type are equal, the
results are calculated to a uniform temperature of 52 '4°. As regards
the magnitude of the velocity constants, the reactions between the
acids and water, and the sodium salts and water respectively, are
unimolecular, and the constants are therefore independent of the units
in which the concentrations are expressed. This, however, is nob the
case for the bimolecular reaction between the salts and sodium
hydroxide. The unit employed was that equivalent to 1 c.c. of 0"085^-
(or 1/11 -SiV) sulphuric acid, 10 c.c. of the reaction mixture being
titrated, and therefore to a concentration of 1/11*8 x 10 = 1/118 gram-
molecule per litre. Hence, if referred to 1 gram-mol. per litre, the
constants in table VIII have to be multiplied by 118, if (as is more
suitable for our present purpose) the unit is 1/10 gram-molecule per litre,
they have to be multiplied by 118. JFor the sake of completeness,
constants representing the rate of the reaction between the bromo-acids
and silver nitrate are included ; the results of this investigation will be
given in a subsequent communication.

ORQANIC COMPOUNDS. PART III.

1835

Table X. — Temperature 52-4°.

CHoBr-CO.JI + H.,0.
1 = 0-000085 ■
[1]

CHoRr-COoNa + H.O,

■'a-=o-oooio

[1-2]

CHoBr'CO.,Na + NaOH.

' A; = 0-0065
[76]

CHaBi-COoH + AgNOa.
A: = 0-0064
[76]

CHMeBr-COoH + HaO.

o-oooi7

[2]
CHMeBr-CO.,Na + H.,0.

o-ooi-i

[16]

CIIMeBr'CO„Na + NaOn.
0-0009
[10]

CHMeBr-CO.,H + AgNO;j.
0-48
[5700]

CHEtBr-COjH + HaO.
0-00022
[2-6]

CHEtBi-COoNa + HaO.
0-002"6
[30]

CHEtBi-CO.,Na + NaOH.
0-0008
[9]

CHEtBr-COaH + AgNOa
1-44
[17000]

The numbers in brackets give the relative initial velocities of the
reactions in iV/lO-solution referred to the slowest — the reaction
between bi-omoacetic acid and water — as unit.

Interaction of the a-Bromo-fatty Acids and Water.

This type of reaction, which may be represented by the general
equation R-CHX'CO.^H + HoO =:R'CH(0H)-C02H + HX, has been
fully investigated in the case of chloroacetic acid and water (Trans.,
1907, 91, 460). As the addition of free halogen acid has very
little effect on the rate of reaction, I have already suggested that
the main change takes place between the non-ionised acid and
water, the reaction, unlike most hydrolytic changes, not being
catalytically accelerated by H* ions. Bodenstein {Zeitsch. EleMro-
chem., 1909, 15, 403) has recently suggested an alternative explana-
tion of these observations — to the effect that it is the CHgCl'COO'
ion which is acted on by water, and that the effect of the hydro-
chloric acid in diminishing the ionisation of the chloroacetic acid
(and thus diminishing the CHgCl'COO' ion concentration) is just
balanced by its catalytic effect. In support of this suggestion it
is stated that with one exception, the hydrolytic decomposition of
certain sulphonic esters (Wegscheider, Zeitsch. phijsikal. Chem., 1902,
41, 52), all hydrolytic actions are accelerated by acids.

There appear, however, to be certain objections to Bodenstein's
view as to the mechanism of these reactions. The effect of acids in
accelerating hydrolytic changes is by no means general. I have
recently shown (Proc, loc. cit. ; Arrhenius Festschrift, loc. cit.) that the
hydrolytic decomposition of a-chlorohydrin by water is only slightly
affected by hydrochloric acid, and as in this case there is no ionisation,
we have a reaction, closely analogous to that under discussion, in which
H' ions exert no catalytic effect. Further, the remarkable results

1836 SENTER: REACTIVITY OF THE HALOGENS IN

obtained in the investigation of the hydrolytic decomposition of
a-bromopropionic acid and a-bromobutyi-ic acid by water, described in
the present paper, appear very difficult to account for on Bodenstein's
theory, but are readily explained on the view as to the mechanism of
these reactions I have advocated. It has been shown that when the
acids alone are heated with water, the " constants " calculated for a
unimolecular reaction diminish fairly rapidly, but in the presence of
excess of hydrobromic acid constants agreeing well for a unimolecular
reaction are obtained. The most rational explanation of this observa-
tion is that both the free CHMeBr-COO' ions and the non-ionised
acid are acted on by water. If we call the constant for the first
reaction Jc^, and that for the second i-eaction k2, the rate of the reaction
is represented by the diiferential equation :

4HBrJ ^ ^^[CHMeBr-COO'lHgO] + A;2[CHMeBr-C02H][H20] (1),
(a.) (b.)

where <i[HBr]/fZf represents the rate at which hydrobromic acid is
liberated, in other words, the rate of the reaction as a whole. When
free bromopropionic acid is taken, the factor (a) is of importance
(it being assumed that the ion reacts more rapidly with water than
the free acid), but as hydrobromic acid accumulates in the system, (a)
becomes smaller and smaller, and finally becomes negligible in com-
parison with (b). This suggestion as to the mechanism of the reaction
can be tested by calculating the initial concentration of CHMeBr*COO'
ions in the free acid solution, and hence the initial velocity of the
reaction, which is the sum of the rate of hydrolytic decomposition of
the non-ionised acid and of the ions. The latter factor can be
determined approximately from the rate of decomposition of sodium
bromopropionate, and the former by extrapolation from the rate in the
presence of excess of hydrobromic acid. The constant for sodium
bromopropionate in ^Y^O-solution at 52*4° is 00014, and, assuming
that the temperature-coefficient for 10° is 3"0, the approximate value
of the constant at 79° will be 0035. At 79° a iV^/10-solution of
bromopropionic acid is ionised to the extent of about 10 per cent., and
the sodium salt to 80 per cent. Hence, the ratio of the CHMeBr-COO'
ion concentrations in the two solutions is 8 : 1, and the constant for
the free acid, as far as the ions are concerned, is 0*035/8 = 00044.
To this has to be added the constant for the non-ionised acid, which, in
the absence of hydrobromic acid, will be approximately 0 0007
(Table II). Hence, the initial velocity at 79° should be 0-0044 -f
U-0007 = 0'0051, and should diminish fairly rapidly, owing to the
formation of hydrobromic acid and the consequent diminution in the
concentration of the CHMeBr-COO' ions. In good agreement with
this, the observed average value of the constant during the first hour

ORGANIC COMPOUNDS. PART III. 1837

is about O'OOSO. It is not practicable in such a case to determine
with accuracy tlie initial velocity by titration after heating for a short
interval of time, as some time elapses before the tubes assume the
temperature of the bath, and considerable uncertainty is thus
introduced.

The view as to the mechanism of the reactions advocated in the
previous paper not only accounts for the fall in the constants for the
two higher acids, but also for the fact that fairly well agreeing
constants are obtained for bromoacetic acid throughout the reaction.
In the latter case, the reactivity of the CHgBr'COO' ion with water
is comparatively so small (compare table V) that the (a) term in
equation (1) is negligible throughout.

A very interesting point in connexion with the bromo-fatty acids is
that the effect of hydrobromic acid in diminishing the rate at which
bromine is displaced becomes greater as the series is ascended. This
result is not directly connected with the "strength" of the acids.
The dissociation constants at 25° are as follows : Bromoacetic acid
000138, a-bromopropionic acid 0*00108, a-bromobutyric acid 0"00106.
Thus the two latter acids are equal in strength, whereas the ratio of the
rates of displacement of bromine in the presence of iV/5-hydrobromic
acid is approximately 2:1. Whether these represent the intrinsic rates
of displacement for the non-ionised acids, or whether the acids are
affected directly by hydrobromic acid to a different extent, is not easy
to decide. Experiments are in progress with the object of throwing
light on this question.

Interaction of the Sodium Salts and Water.

The results given on p. 1831, especially the observation that the
velocity constants are rather greater in iV^lOO-solution than in NjlQ-
solution, show conclusively that, at least in dilute solution, the negative
ion, and not the non-ionised salt, is the active agent. Hence there
appear to be only two possible methods of representing the mechanism
of the reactions :

(1) The anion R-CHBr-COO' reacts directly with water according
to the equation R-CHBr-COO' + R.p = R-CH(OH)-COO' + HBr.

(2) The bromine is displaced along with the negative electron, as
represented by the typical equation :

R-CHBr-COO' -> R-CH-COO-hBr',
the residue immediately uniting with water to form the corresponding
hydroxy-fatty acid, R-CH(0H)-C02H. The first alternative is rather
difficult to reconcile with the fact that the velocity increases with the
complexity of the anion, the ratio bromoacetate : bromopropionate :
bromobutyrate being approximately 1 : 14 : 26 (table X). The fact

1838 SENTER: REACTIVITY OF THE HALOGENS IN

that the methyl group is, in general, more positive than hydrogen can
scarcely account for the fact that the CHMeBr*COO' ion is fourteen
times more reactive than the CHjBr'COO'ion, more especially as the
introduction of larger groups might be expected to retard the action
owing to " steric hindrance."

On the alternative view as to the mechanism of the reaction, a
plausible explanation of the accelerating effect of substitution can
be given. It is well known (compare Van't Hoff, Vorlesungen, III,
p. 131) that the tendency of maleic acid to eliminate water, forming
the anhydride, is greatly increased by substituting methyl groups for
hydrogen, for example, dimethylmaleic acid is only known in the form

of the anhydride, M Ci^^' ^^^ ^^® usual explanation is that

owing to the greater space occupied by the larger substituting groups
the two carbonyl groups are urged nearer together, the removal of
water between the two groups being thus facilitated. On similar

E-CHBr

lines it mayj be suggested that in the compound i ^ the

bromine atom and the negative electron are urged nearer in space
the larger the group R, thus facilitating the formation of Br' ions. If
this reaction is to any extent reversible, the addition of alkali
bromides ought to retard it, and, in accordance with this, it has
already been pointed out that reactions of this type are considerably
retarded by sodium bromide (p. 1832).

Interaction of the Sodium Salts and Sodium Hydroxide.

The results given in the present and former papers appear to show
that, as regards the first member of the series, bromoacetic acid, the
reaction between its sodium salt and sodium hydroxide in dilute
solution is best represented by the equation CHgBr'COO' + OH' =
CH2(0H)'C00' + Br'. A remarkable difference between the re-
action and that of ester saponification, however, is that in the
former case the CHgBr-COO' ion is acted on almost as rapidly by
water as by dilute alkali.

Thejresults quoted in table VIII show that the sodium salts of the
two higher bromo-fatty acids are acted on less rapidly in the presence
of alkali than is sodium bromoacetate. Comparison with the data in
table V shows that for the former two salts the action of water
cannot be neglected in comparison with that of alkali. In the case of
sodium a-bromopropionate, for example, we are dealing with two
simultaneous reactions, represented by the equations :

CHMeBr-C00' + H20 = 0H-CHMe-C00' + H* +Br' (1).
CHMeBr-C00' + 0H'=*0H-CHMe-C00 +Br' (2).

ORGANIC COMPOUNDS. PART III. 1839

If dxjdt represents the rate at which bromine is displaced as the
result of the simultaneous reactions (1) and (2), the rate of the reaction
is represented by the differential equation :

^ - ^•i[CHMeBr-COO'][H20]+;fc2[CHMeBr-COO'][OH'] (3).

If the salt and sodium hydroxide are taken in equivalent concentra-
tion, and the latter, at the time t, is represented by a x, equation
(3) simplifies to

= Aj(a - a;) + k.,{a - x)"- = [k^ -f k.,{a - x)'\{a - x) (4),

the concentration of the water being taken as constant.

On integrating equation (4), putting x = 0 when t =Q, we obtain

Z;,< = 2-30261og, tVtM«Z_*l> (5).

These formulae must now be applied to the experimental results
given in table VIII. Perhaps, the simplest method of procedure is
to find an approximate value for k^ by substituting in equation (4)
known values of (a — x) and ^^ (the latter being obtained at once from
the results given in table V), and to check these values by means of
equation (5). In this way, yi;2 = 0*0000 8 has been obtained as the
average value of the velocity constant for the reaction between
sodium bromopropionate and sodium hydroxide, and A;2 = 0"00007 as
the corresponding constant for the reaction between sodium bromo-
butyrate and sodium hydroxide. In order to reduce these numbers
to a concentration of 1/10 molecule per litre, they have to be multi-
plied by 11 "8 (compare p. 1834), and thus the values A;2 = 0*0009 and
00008 quoted in table X are obtained.

A little difficulty in checking these values by substitution in
equation (5) arises from the fact that ^j diminishes somewhat
throughout the reaction owing to the retarding influence of the
products of the reaction. It has therefore not been considered
necessary to quote the results of the calculations in detail, as the
numbers given are sufficiently accurate for our present purpose.

Two interesting I'esults have thus been obtained; (1) that in con-
trast to ester hydrolysis the action of alkali on the sodium salts of
the bromo-fatty acids is not much more rapid than the action of water
alone ; (2) there is a fall in reaction velocity with increasing substitu-
tion, the ratio bromoacetate : a-bromopropionate : a-bromobutyrate
being approximately 9 : 1'l : 1. The first observation becomes more
intelligible when it is borne in mind that, whereas in ester saponifica-
tion a negatively charged group (the OH' group) is acting on a neutral
molecule, in the case now under discussion the reaction takes place
between two negatively charged groups (compare Meyer, Zeitsch.

1840 SETTER: REACTIVITY OF THE HALOGENS IN

physikal. Chem., 1909, 67, 257). In the latter case, the repelling
effect of the two similar charges may well exert a great retarding
influence on the reaction velocity. This view becomes still more
plausible when it is borne in mind that the action of alkali on the
electrically neutral a-chlorohydrin is enormously more rapid than that
of water, just as in ester hydrolysis (Senter, loc. cit.).

The diminution in the velocity as the series is ascended is perhaps
most readily accounted for on space considerations, the action of
OH' ions on the bromine being the more retarded the greater the
volume of the substituting group.

General Conclusions.

There do not appear to be any previous results with which those
given in the present paper can be directly compared. Bischoff (Ber.,
1899, 32, 1748) carried out an extensive series of experiments on the
reaction between sodium alkyloxides and bromo-fatty esters. In the
case of sodium ethoxide and bromopropionic ester, for example, the
main reaction may be represented by the equation

EtONa + CHMeBr-COjEt = OEt-CHMe-CO.^Et + NaBr ;
but secondary reactions, such as hydrolysis of the bromo-fatty ester,
also occur in this and the corresponding reactions with other esters
and alkyloxides. For two reasons, Bischoff's results cannot be regarded
as giving a very satisfactory picture of the influence of substituting
groups on the rate of reaction. In the first place, the majority of the
experiments were made in light petroleum, in which the sodium alkyl-
oxide was suspended, and accidental circumstances play a great part
in determining the course of such reactions in heterogeneous systems.
Further, the reactions were allowed to proceed almost to completion in
many cases before observations were made, and therefore the results
throw very little light on the influence of substitution on the reaction
velocity. One of Bischoff's main objects was to find what substances
were formed in the course of the reaction, and this was sufiiciently
secured by his method of experiment. A repetition of some of his
observations, with due attention to the rate of reaction, would probably
lead to interesting results.

Slator (Trans., 1904, 85, 1286; 1905, 87, 482; this vol., 93) has
made an extensive series of measurements on the rate of reaction
between organic halogen compounds and sodium thiosulphate, and
shows that for compounds of the same type the rate of the reaction
generally diminishes with increasing complexity of the substituting
group. The earlier experiments of Wislicenu.*, Menschutkin, and Hecht,
Conrad and Briickner with other reagents also show that the activity
of the halogens is diminished by substitution of alkyl groups for

ORGANIC COMPOUNDS. PART III, 1841

hydrogen. This is evidently the typical behaviour, and corresponds
with the results with sodium hydroxide described in the present paper.
Quite a different order of activity is obtained when the rate of reaction
between halogen compounds and silver nitrate is measured (Burke and
Donnan, Trans., IDO-t, 85, 555). This type of reaction will be dis-
cussed later, when the results of measurements now in progress are
available, but the provisional results quoted in table X show that the
order of activity of the bromo-fatty acids with silver nitrate is ijuite
different from the typical one.

The results promise to throw some light on the so-called " Walden
inversion," the investigation of wiiich has recently been again under-
taken by Fiscber {Ber., 1907, 40, 489) and by McKenzie (Trans.,
1908, 93, 811). Walden {Ber., 1899, 32, 1818), in order to account
for the different action of alkalis and of silver salts on the halogen
derivatives of fatty acids, lias suggested that such compounds as
bromopropionic acid are dissociated to a considerable extent in solu-
tion with production of halogen ions, and that in the pi-esence of
alkalis direct exchange takes place between the halogen ions and
the OH' ions. In the reaction between the halogen-fatty acids and
silver nitrate, on the other hand, it is considered that complex addition
compounds are formed which, after rearrangement, give rise to the
final products.

TJie results described in the present series of papers, especially the
fact that sodium bromide has practically no effect on the rate of dis-
placement of bromine in a-bromopropionic acid by water, appear
entirely to disprove Walden's theory that halogen ions are present in
solutions of the free halogen-fatty acids. Even in the case of
solutions of the sodium salts, it is very improbable that the anions
give rise to halogen ions by ionisation, and the fact that the reaction
between sodium bromoacetate and sodium hydroxide is bimolecular
shows that in any case the rate at which halogen ions are formed is
not the sole determining cause of the observed reaction velocity. The
view of the mechanism of the reaction advocated in the present paper
does not postulate an ionisation of the ordinary type, in which positive
and negative ions are formed in equivalent amount, but the slow
removal of a Br' ion, leaving a neutral molecule. On the other hand,
there is no reason to doubt that the mechanism of the displacement
of halogen by bydroxyl under the influence of alkali and of silver
salts respectively is essentially different. The matter will be further
discussed in connexion with the experiments on the reactions of
silver salts with halogen-fatty acids now in progress.

In conclusion, I desire to express my thanks to the Directors of the
Davy-Fai'aday Research Laboratory of the Koyal Institution, where

1842 WADE AND FINNEMORE: ethyl ETHER. PART I.

part of the experimental work has been carried out, and also to
Dr. Fliirscheini, with whom I have had the advantage of discussing
the subject matter of the paper.

Chemical Depaktment,
St. Mary's Hosi'ital Medical School, W.

CCIW— Ethyl Ether. Part 1. The Influence of Water
and Alcohol on its Boiling Point.

By John Wade, D.Sc, and Horace Finnemore, B.Sc.

It is usually assumed that ether is pure when readily recognised
impurities, such as alcohol, aldehyde, and hydrogen peroxide, have
been eliminated by washing, and dissolved water has been removed
by digestion with calcium chloride or quicklime, followed by sodium
or phosphoric oxide. The boiling points given by modern workers
are concordant: Schiff {Annalen, 1883, 220, 232), Perkin (Trans.,
1884, 45, 474), and Ramsay and Young {Fhil. Trans., 1887, 51,
57) all agree on 34'6°. The discrepancies between the densities,
however, are greater tlian can be attributed to experimental error.
In the following table, which embodies the principal data, the
reductions have been made by means of the coefTicients of expansion
determined by the respective authors, except with Perkin's number,
for which a mean coefficient was used; Squibb's values have also
been corrected for expansion of glass and for buoyancy. Squibb
and Oudemans give values for several specimens, of which the
extremes have been taken :

Densities.

Authority. Drying agent.

Kopp (Ann. Phys. Chem.,

1847, 72, 228) Calcium chloride

Perkin {loc. cit., 1884) Phosphoric oxide

Squibb {Ephemeris, 1885,

2,592) Calcium chloride

Oudemans {Eec. trav. chim. ,

1885, 4, 269) Limeand sodium

Pierre (Ann. Chim. Phys.,

1845, [iii], 15, 260) Calcium chloride

Original.

0-72895 6-974°
0-72008 15715°

0-71928 1574°
0-71908 15°/4°
0-73128 4°/4°

0-73600 0°/4°
0-73586 074°

Reduced
to 074°.

0-73658
0-73625

0-73633
0-73612
0-73611

(0-73600)
(0-73586)

Reduced
to 15715".

0-72058
(0-72008)

0-72004
0-71984
0-71982

0-71983
0-71969

0-73591 074° (0-73591) 0-71975

Accurate fractionation of various specimens of ether, which
had been carefully purified by the processes employed above, showed

WADE AND FINNEMORE: ETHYL ETHER. PART I. 1843

that in no case was a really liomogeneous product obtained ; every
specimen was resolvable into constituents having varying boiling
points and densities. It was hoped at first that it would be possible
eventually to isolate the pure substance in this manner in accordance
with previous experience; and, indeed, in the majority of instances,
principal fractions were obtained which agreed in boiling point to
0"01°. The want of uniformity, however, in the densities of these
fractions — which, in ordinary circumstances, would certainly have
been found to be pure — showed that excellent agreement in boiling
point might exist concurrently with appreciable variations in com-
position, and that it was doubtful whether finality had been
reached.

Indications afforded by the earlier fractionations rendered it
probable that this curious disagreement between the two constants
was due to the formation of a physical mixture, or mixtures,
analogous to the mixtui'es of constant boiling point isolated by
Young and Fortey from alcohol (Trans., 1902, 81, 717), and by
the present authors from chloroform (ibid., 1904, 85, 1938). The
behaviour of artificial mixtures of ether with water and alcohol
was therefoi'e investigated. It was eventually found that, on the
one hand, a small proportion of water appreciably depresses the
boiling point of ether, owing to the formation of a definite binary
mixture ; and, on the other hand, that a small proportion of
alcohol, although not forming a definite mixture of this class, clings
to ether with remarkable persistence, and appreciably raises its
boiling point.

Unless, therefore, all the alcohol, and all but a trace of the
water are first removed, it follows that it is impossible to obtain
pure ether by any process of fractional distillation ; and that
constancy in its boiling point, especially as determined in the
course of ordinary rectification, may be due merely to the mutual
cancelling of these two opposing factors, and cannot, as is usually
assumed, be accepted as conchxsive evidence of the purity of this
substance.

I. — Examination of Ether Purified hy Existing Processes.

The experiments described below were made with commercial
" pure " ether, prepared from rectified spirit and pure sulphuric
acid. The sp. grs. of the various specimens (07213, 0'7222, 07214,
0'7219 at 15°/ 15°) fell within the customary limits; water and
appreciable quantities of alcohol w^ere invariably present.

The various products, after treatment as described, were frac-
tionated with the usual precautious through a Young evaporator

1S44< WADE AND FINXEMORE: ETHYL ETHER. PART I.

column having eight sections.* The boiling points, which were
checked by reference to standard thermometers, are expressed on
the hydrogen scale, and reduced by means of Ramsay and Young's
vapour pressure data (Joe. cit.) to 760 mm. at 0° and Lat. 45°.
The sp. grs. were determined at t°lt° in a large (40 c.c.)
pyknometer of Ostwald-Sprengel pattern, and corrected to vacuum.
They were reduced to 15°/ 15° by means of the dilatation constants
of Pierre and Oudemans, and are correct to one or two units in
the fifth place.

The individuality of a fraction, such as is afforded by a very
efficient still-head, is indicated by the relative constancy of its
boiling point, and is conveniently measured by the ratio of its
weight (Aw) to the increment of temperature (A^). This ratio
rises to a maximum as the boiling point of each individual (whether
chemical or physical) is reached, after which, except at the end
of a series, it falls again to a minimum. When maxima are very
close together, as in the present work, and the member of higher
boiling point is in large excess, the temperature of the lower
maximum is invariably raised, sometimes to such an extent as
altogether to obliterate it. To enable different fractionations to
be compared, the weight is reduced to a percentage of the
total quantity (W) treated. In the following tables, the ratio
100Aw/WA< is indicated by the symbol A.

(a) Simple Desiccatwn : Calcium Chloride, Lime, Sodium,
Phosphoric Oxide, Calcitcm.

i. Commercial pure ether (500 grams) was shaken with powdered,
recently fused calcium chloride (40 grams) at intervals for six
days, when crystals of the hydrated salt became visible. A portion
(125 grams) was poured off and fractionated:

B. p.

Weight.

A.

B. p.

Weight.

A.

33-1 —34-39'

8-4

5

34-45—34-49°

32-7

0^5

34-39

30-5

840

34-49

23-0

1840

34-39—34-43

20-8

420

Residue

12-2

34-43— 34-45

11-7

470

Loss

5-7

—

There were two maxima, and therefore two constituents. The
head fraction became turbid when mixed with carbon disulphide,
and therefore contained water. This was confirmed by the densities.
The sp. gr. of the original ether was 0-72137, which, after the
desiccation, fell to 072036. The sp. gr. of the second, third, and

* Much trouble was caused at the outset by excessive loss through evaporation,
even with an eflBcient condenser the heavy vapour pouring steadily out of the
mouth of the receiver. It was sufficiently checked ultimately by keeping both
condenser and receiver nearly at 0".

WADE AND FINNEMORE : ETHYL ETHER. PART J.

]845

fourth fractions (which were mixed in order to fill the pyknometer)
was 0-72024, and that of the fifth and sixth 0-72019. The
accumulation of water in the head fraction, the formation of two
maxima, and the progressively falling densities, indicate the
presence of a binary mixtui'e of ether and water, having a boiling
point not much below that of pure ether.

Further drying still further lowered the density. A portion of
the partly dried product, sp. gr. 0-72036 (150 grams), was kept over
sodium shavings (2*4 grams) for five days, and then rectified from
the metal. The sp. gr. fell to 0-72020. To another portion (185
grams), excess of phosphoric oxide was added (19 grams required).
After rectification, the sp. gr. fell to 0-72001. These specimens were
not fractionated at the time, and when examined later had
deteriorated.

ii. As the action of calcium chloride is slow, some commercial
ether (300 grams) was digested with sodium shavings until gas
ceased to be evolved. Next day it was rectified over phosphoric
oxide. The sp. gr. was 0-72015. A portion (160 grams) was
fractionated :

B. p.

Weight.

A.

B. p.

Weight.

A.

33-2 —34-35''

3-6

2

34-52— 34-56

19-0

300

34-35— 34-42

6-0

55

34-56-34-58

16-7

520

34-42— 34-44

7 6

240

34-58

160

1000

34-44—34 46

15-4

480

34-58—34-60

9-7

300

34-46-34-50

16-0

2.o0

Kesidue

10-0

—

34-50—34 52"

20-8

650

Loss

20-0

—

There were three distinct maxima, and apparently three con-
stituents. The first and second coincided with those obtained after
drying with calcium chloride, but the third, and most important,
was at a higher temperature. The additional maximum seemed to
indicate a second binary mixture, possibly ether-alcohol. This is
discussed later (p. 1850). The fractions were too close for accurate
determination of density, but the separation was obviously inferior
to that effected with the calcium chloride product (i).

iii. Metallic calcium was comparatively ineffective as a desiccating
agent. Some commercial ether (160 grams) was boiled with calcium
raspings (5 grams) for four hours, and then kept for a week at the
ordinary temperature. As a slow action was still proceeding, the
experiment was then stopped. The sp. gr. of the rectified product
was 0-72024.

(b) Oxidation and Desiccation.

i. Some commercial ether (150 grams) was shaken with a 4 per
cent, solution of chromic acid (50 c.c.) and finally boiled for an
hour (compare Dunstan and Dymond, Trans., 1890, 57, 574;

VOL. XCV. 6 F

1843 WADE AND FINNEMORE : ETHYL ETHEK. PART 1.

Lassar-Coliu, AnuaUti, 1895, 284, 226). Aldehyde having been
removed by digestion with silver oxide, the j^'oduct was dried with
calcium chloi-idc. A portion (92 grams) was fractionated :

B. p.

Weight.

A.

R. p.

Weight.

A.

32 -6 —34-25°

3-1

2

34-45—34-49°

13-9

380

34-25— 34-39

9-5

74

34-49-34-51

12-5

680

34-39— 34-43

8-9

245

34-51-34-53

10-9

590

34-43-34 45

10-1

550

Residue and loss

23-1

—

The two maxima corresponded fairly with those of the calcium
chloride jDroduct, but were much less definite. There was much
dissolved Avater in the head fraction, and an appreciable amount
of aldehyde. The fractions were not large enough for accurate
determination of density.

ii. Slightly alkaline permanganate, under suitable conditions,
oxidises alcohol directly to acetic acid, or perhaps oxalic acid. It
avoids the formation of aldehyde, and oxidises this if already
present; it is thus well adapted for the purification of ether
(Frau9ois, /. Fliarm. Chim., 1897, [vi], 5, 521). Some commercial
ether (150 grams) was shaken wdth aqvteous permanganate (2'5
grams in 50 c.c, with a little alkali hydroxide), with which it was
finally boiled for half an hour. The rectified product was dried
with calcium chloride, and fractionated (118 grams):

B. p.

Weight.

A.

B.p.

Weight.

A.

32-65—34-24°

3-0

2

34-48—34-50°

120

510

34-24—34-40

11-1

59

34-50

16-1

1370

34-40—34-42

11-4

480

34-50—34-52

17-7

750

34-42-34-44

14-4

610

Residue

7-0

—

34-44—34-48

13-9

290

Loss

11-4

—

The second maximum was sharjoer than with chromic acid.
There was no aldehyde in the head fraction, but a considerable
amount of water.

iii. The best oxidation process examined was a modification of
the preceding method, due to Dr. Pierz, which was kindly com-
municated to the authors by Dr. M. O. Forster, in whose laboratory
it has been employed for some time past. Commercial ether (200
grams; was digested with a mixture of powdered potassium per-
manganate (5 grams) and potassium hydroxide (5 grams) for a
week at the ordinary temperature, the bottle being occasionally
shaken. It was then poured off and rectified. The sp. gr. was
0'72020; another specimen subsequently prepared in the same man-
ner had sp. gr. 0"72021. A portion (181 grams) was fractionated:

B.p.

Weight.

A.

B.p.

Weiglit.

A.

33-2 —34-39°

9-7

4

34-45—34-47°

11-4

315

34-39-34 41

12-4

340

34-47—34-51

22-0

305

34-41—34-43

11-8

330

34-51

88-4

4890

34-43— 34-45

10-9

300

Residue and loss

14-4

—

WADE AND FINNEMORE: ETHYL ETHER. PART I.

1847

Tho first maximum was the least sharp of any yet observed, and
was evidently on the point of obliteration. The second was much
the sharpest, and represented nearly half the total product; the
sp. gr. of this fraction was 0'7200G. The head fraction contained
a little water, but aldehyde was absent.

(c) Exhaustive Washing and Desiccation.

Lieben (Annalen, Siippl., 1871, 7, 218) recommends removing
alcohol by shaking with small quantities of water until the iodoform
test gives a negative result; he found 20 or 30 washings necessary.
Ramsay and Young (loc. cit.) found that 50 washings were needed.
Squibb {loc. cit.) employed relatively large quantities of water,
with which the ether was agitated mechanically for considerable
periods; he found 6 washings sufficient, in the course of which,
however, one-third of the ether was lost. Oudemans (loc. cit.),
using Lieben's method, stopped after 15 or 20 washings. To test
this method, some commercial ether (700 grams) was shaken for
fifteen minutes at a time with successive small quantities (50 c.c.)
of water. After the 16tli washing, when the weight had been
reduced to 570 grams, the iodoform test ceased to give a definite
indication of the presence of alcohol in the wash-water.*

i. Part of the washed ether (250 grams) was dried by Oudemans'
method {loc. cit.). It was first digested with fresh quicklime (50
grams, from marble) for two days in a well-filled flask, and then
rectified from the lime. The first and last portions of the distillate
having been rejected, the remainder was then digested with sodium
shavings (2'4 grams), with which there was a slight, although
immediate, action. Next day, the ether (183 grams) was rectified
from the sodium; as the sp. gr. was then 0'72013, further examina-
tion was unnecessary.

ii. The remainder of the washed ether (307 grams) was digested
with calcium chloride for two days, and then rectified from
phosphoric oxide (37 grams). The product (240 grams) was frac-
tionated; its sp. gr. was 0"71999:

B. p. Weight. A,

34-48— 34 •49° 24-0 1000

34 49 173 0 7200

Residue and loss 16 '4 —

The first maximum had now practically disappeared. The second
indicated a highly purified product, representing nearly three-
fourths of the whole; its sp. gr. was 0'71994. This was the best
result obtained with ether purified by existing processes.

* The ether employed in this work had already been washed to a certain extent
in the course of manufacture.

6 F 2

B.p.

Weight.

A.

33-58— 34-38"

4-2

2

34 38—34 42

101

105

34-42-34-48

12-3

85

1848 WADE AND FINNEMORE : ETHYL ETHER. PART I.

(</) Sumnmry of Results with Ether Purified hy Existing Processes.

Sp. gr.

Differential <- "^ ^

of best Best

No. Treatmcut. fractions. B. p. "Whole. fraction.

b i Chromic acid and calcium chloride... 680 34 'SI" — —

a ii Sodium and phosphoric oxide 1000 34'58 — —

h ii Aqueous permanganate and calcium

chloride 1370 34-50 — —

a i Calcium chloride only 1840 34-49 0-7'2036 0-72019

« iii Metallic calcium — • — 0'720'24 —

6 iii Solid permanganate and alkali 4890 34-51 0-720-20 0-72006

a i Calcium chloride and sodium — — 0-72020 —

c i Washing; lime and sodium — — 0-72013 —

a i Calcium chloride and phosphoric

oxide — — 0-72001 —

c i Washing ; calcium chloride and phos-
phoric oxide 7200 34-49 0-71999 0*71994

From these results, it -was clear that the boiling point of pure
ether is very near 34'50°, and its sp. gr. probably below 0'71994.
As -was to be expected, the sp. grs. decreased as the differentials
increased; but there was no evidence of finality. A considerably
lower sp. gr. was, in fact, obtained at a later stage by methods
which are still under investigation. The influence of water and
alcohol were obviously very important factors in the purification,
and needed examination before further progress could be made.

II. — Isolation of Binary Mixtures of Ether and Water: Investi-
gation of Supposed Binary Mixture with Alcohol: Absence of
Ternary Mixture. m

(a) Binary Aqueous Mixture.

i. Ether and Excess of Water. — Commercial ether (130 grams)
■was fractionated in presence of water (50 grams) :

B. p.

Weight.

A.

B. p.

Weight

33-7 —34-10°

5-3

10

34-19—100°

small

3410— 34-19

14-1

120

Residue

50-5

34 19

96-2

7400

Loss

13-2

Practically three-fourths formed a homogeneous product of lower
boiling point than pure ether. This was quite clear when first
collected (sp. gr. 0-7245), but there were numerous small drops of
water in the fractionating column, and after a time minute drops
also appeared in the distillate. When the layer of ether in the
still had disappeared, the boiling point rose at once to 100°, and

WADE AND FINNEMORE : ETHYL ETHER. PART I. LS4-0

the distillation was stopped. The whole distillate was now dried
roughly with calcium chloride, and fractionated (100 grams) :

B. p.

Weight.

A.

n. ,,.

Weight.

A.

33-9 —34 16°

3-4

13

34 36 34 40"

18-4

460

3416— 34-30

14-9

105

34 •10—34-46

15-3

'255

34-30— 34-36

10-7

180

34 -46-34 -60

16-2

405

Residue aud loss

21-1

—

The product closely approximated to those previously obtained
from purified ether. There were two distinct maxima, and the
head and second fractions showed appreciable amounts of water
when tested with carbon disulphide.

In order to define the boiling point accurately, and ascertain
the composition of the aqueous mixture, purified ether, b. p. 3449°,
sp. gr. 0"72002 (50 grams), was fractionated in presence of water
(50 grams) :

B.p.

Weight.

A.

33-8—34-15°

7-6

44

34-15

35-0

7000

35-0—100

small

—

The boiling point was here exceedingly sharp, and became
constant practically as soon as equilibrium was established. At
15°, the ether was just about saturated with water, the percentage
of which, .calculated from the sp. gr., was TS.* The loss by evapora-
tion was too uncertain to allow of analysis by distillation.

* The sp. gr. of highly purified ether, sp. gr. 0'71982, saturated with water at
various temperatures, was determined hydrostatically by means of a weighted glass
sinker displacing about 30 c.c. The proportion of water was thou calculated,
allowing for contraction.

Temperature 20° 18° 16° 15° 14° 12° 10°

Sp. gr. atr/«° 0-7193 0-7214 0-7234 0^7244 0'7254 0-7272 0-7290

Weight of water dissolved by

Igramofether 0-013 0-013 0-013 0-013 0-0125 O-Qll 0009

The contraction was determined from the sp. gr. of solutions of known com-
position, which were prepared by agitating ether in a well-stoppered bottle with
water introduced in a small bulb.

I. 0-6057 water in 50-31 ether, sp. gr. 0-71984, gave solution sp. gr. 0-72415.
II. 0-4042 „ 50-92 „ „ 072000, „ „ „ 0-72423.

I. Sp. gr. calculated 0-72228 ; contraction, 0-26 per cent.
II. ,, ,, 0-72205; ,, 030 ,,

The values given by various authorities for the solubility of water in ether are
very discordant, possibly owing to the difficulty of purifying the ether — the
solubility is greatly increased by even a very small quantity of alcohol ; it is
significant, however, that if the important correction for contraction be omitted, the
values calculated from the above data become 0-023 from 20° to 15°, and 0-019 at

T850 WADE AND FIXNEMORE : ETHYL ETHER. PART I.

ii. Water and Excess of Ether.— The complete separation of two
constituents, boiling within 0"35° of one another, is impracticable,
and jDrevioiis experience had shown that in such cases the con-
stituent of higher boiling point can only be isolated when present
in very large excess. Separation of pure ether in this manner was
eventually effected from an imperfectly dried product, from which
it is believed that every impurity but water had been removed.
Some highly purified ether, which, when fully dried with phosphoric
oxide, had b. p. 34-51°, A 8500, and sp. gr. 0-71982, was treated,
after roughly drying with calcium chloride, with an amount of
phosphoric oxide known to be insufficient. It was then fractionated
(300 grams) :

B. p.

Weiglit.

A.

B. p.

Weiglit.

A

34-35— 34-42°

8-8

4

34-46—34-48°

11-0

180

34-42— .34-49

21-6

100

34-48 — 34-51

22-8

250

34 44-34 46

23-6

390

3451—34-52

194-0

6470

Residue aud loss

18-2

—

There were two maxima, which corresponded closely with those
of the ether purified by Fierz's method (p. 1846). The sp. gr. of
the third fraction (with part of the second) was 0-72012, and that
of the fourth and fifth 0-72011. The sp. gr. of the main fraction
was 0-71986, or very nearly that of the completely dried product.
Ether, sp. gr. 0-72012, contains 0-14 per cent, of water. The
elimination even of this small proportion of water as a more
volatile constituent completes the proof of the formation of a
binary mixture of ether and water of minimum boiling point.

Ether therefore forms with water a binary mixture, which boils
at 34-15°, and contains approximately 1-3 per cent, of water.

(h) Supposed Bi7iary Mixture vith Alcohol.

i. Ether with much Alcohol.- — Some of the ether, sp. gr. 0-72013,
which had been dried with sodium and phosphoric oxide (p. 1845),
was fractionated with an equal weight of 99-8 per cent, alcohol
(50 grams) :

B.p.

34-62— 34 -rS"

34-73

34-73-34-81
34-81—35-0
35 0 —78-05

Weight.
5-7
9-6
8-2
7-2
1-7

A.

50
960

100
40
0-04

B.p.

78-05—78-21°
78-21—78-23
78-23—78-25
78-25-78 27
Residue and loss

Weight.

6-5

9-2

10-9

15-0

26-0

A.
40
460
545
750

10°. The following are the amounts of water stated to be dissolved by 1 gram of
ether at the respective temperatures :

Klobbie (Zcitseh. physikal. Chem., 1897, 24, 615)

Schuncke (j6i<^., 1894, 14, 334) { 0-0272'^

Napier (5mK. Soc. chivi., 1878, [ii], 29, 122) .. .

Herz {Ber., 1899, 31, 2671)

0-012—0-0127 at 20°
10
20
0-0278 ,, 12

0-0407 „ 22

WADE AXD FINNEMORE : ETHER ETHER. PART I.

1851

The elevation of boiling point originally noticed with this speci-
men (34'68°) was now still more decided; absolutely nothing passed
over until well above the boiling point of pure ether. The tem-
perature rose slowly until most of the ether had distilled, and then
very rapidly to the boiling point of alcohol. The sp. gr. of the
main ether fraction was 0"7211, corresponding with about 1*6 per
cent, of alcohol. There was no indication of other maxima, but
this was possibly due to the large amount of alcohol in the still
(compare ethyl acetate, Wade, Trans., 1905, 87, 1664). Repetition
with rather different proportions gave a substantially identical
result, the main ether fraction boiling at 34"75°, and the alcohol
fraction at 78'31°. In both cases the head fraction remained
clear when mixed with excess of carbon disulphide; but water may
nevertheless have been present, as a very little alcohol greatly
increases its solubility in this mixture.

ii. Ether irifh lit fie Alcohol. — Some highly purified ether, sp. gr.
0"71986 (150 grams), was fractionated with a little nearly anhydrous
alcohol (I'o grams):

B. p.

Weight.

A.

B.p.

Weight.

A.

34-35— 34-53'

10-6

40

34-65'

23-9

1580

34-53-34-59

7-7

80

34-65-34-67

26-3

870

34 59—34 63

26-7

440

34-67- 34-69

13-7

450

34-63- 34-tJ5

11-8

390

34-69—34-77

15-9

130

Residue and loss

14-9

—

There were two maxima, both above the boiling point of pure
ether and corresponding fairly with the two upper maxima of the
abnormal ether (p. 1845). The sp. gr. of each maximal fraction
was 0-7201, but after the second maximum the sp. grs. increased
rapidly; that of the tail fraction was 0-7207. The sp. gr. of the
residue was 0-7374 ; evidently little of the alcohol had passed over.

The collected distillates were refractionated (1280 grams),
excluding: the residue :

B.p.

AVeight.

A.

B. p.

Weight.

A.

34-0 —34-47°

9-1

14

34-50— 34-52'

9-9

380

34-47—34-49

10-1

395

34 52-34-53

77-1

6030

34-49—34-50

11-2

875

Residue and loss

10-8

—

The maxima, which were now much more definite, had fallen
very near the boiling point of ether, although the upper one was
still distinctly high. The sp. gr. of this fraction was 0-72019. The
sp. gr. of the residue was 0-7235. Most of the alcohol which had
passed over in the first fractionation had therefore been eliminated.

Repetition with suitable variations gave substantially the same
results. There was no sign of a third maximum except on one
occasion, when a little water was accidentally introduced in pre-
paring for a refractionation. Highly purified ether, sp. gr. 0-71982

1852 WADE AND FINNEMORE: ETHYL ETHER. PART I.

(150 grams), on fractionation with a little 99-8 per cent, alcohol
(1-5 grams) had given maxima at 34-53° (A 385) and 34-63°
(A 3510 ; sp. gr. 0-7202). The sp. gr. of the residue was 0-7323. The
collected distillates were now refractionated as stated (114-0 grams;
perhaps 0"2 gram of water) :

B. p.

Weight.

33-9 —34-47°

9-2

14

34-47

9-3

815

3 i -47— 34-49

4-2

185

34-49

11-7

1025

34 -49— 34 •5-2

11-7

340

B. p.

Weight.

A.

84-52"

34-7

3020

34-5-2—34-53

15-6

1370

34-53— 3457

4-0

90

R esidue

10-0

—

Loss

3-6

—

There were here undoubtedly three maxima. The sp. gr. of the
two head fractions was 0'7207; of the fourth and fifth (with part
of the sixth), 0-72047; of the sixth, 0-72049; and of the residue,
0-7215. The water had evidently passed into the head fractions;
the alcohol, as before, was in process of elimination. This normal
differentiation, taken in conjunction with the extreme closeness of
the three maxima, rendered it probable that the middle maximum
was a false one — a shadow of the first, as it were — due to elevation
of boiling point by the alcohol in the still as the concentration
increased.

iii. Ether with very little Alcohol. — It was thus probable that
the lower maximum, which ajDpears so persistently in the preceding
fractionations, was merely due to a trace of water, and that ether
does not form a binary mixture with alcohol. Direct proof of this
could only be furnished by fractionating anhydrous ether with
anhydrous alcohol in a dry atmosphere. Practically decisive
evidence was obtained, however, by fractionating imperfectly dried
ether, sp. gr. 0-72001 (150 grams), with a very little anhydrous
alcohol (0-5 gram) :

B. p.

Weight.

A.

33-5 -34-47°

14-0

10

34-47—34-49

21-6

7-20

B.p.

Weight.

A.

34 -49'

65-1

4340

Residue

39-0

—

Loss

10-8

—

The sp. gr. of the first two fractions was 0-72018; of the main
fraction, 0-71996; and of the residue, 0-72106. The boiling point
and sp. gr. of the main fraction were those of fairly good ether,
distinctly better than the original. The amount of water required
to raise the sp. gr. of 35-6 grams of ether from 0-72001 to 0-72018
is 0'028 gram. The amount which must be withdrawn in order to
lower the sp. gr. of 65-1 grams of ether from 0-72001 to 0-71996
is 0017 gram; the difference is not greater than would be accounted
for by the residual hygroscopic moisture adhering to the glass of
the apparatus. The amount of alcohol required to raise the sp. gr.

WADE AND FINNEMORE : ETHYL ETHER. PART I.

1853

of 39"0 grains of ether from 0"72001 to 0'72106 is approximately
06 gram, and is fairly well accounted for by the 05 gram added.

It may be concluded that ether does not form a binary mixture
with alcohol, although its boiling point, and that of the binary
mixture with water, is markedly raised even by small quantities of
this impurity.

(c) Absence of a Ternary MixUire.

So far as the authors are aware, there is no instance of the
formation of a ternary mixture without the accompanying
formation, under appropriate conditions, of the three possible
binary mixtures. This does not seem a priori impossible, however.
At any rate, the point is doubtful, and, although the occurrence of
the third maximum in the foregoing fractionations had been fairly
satisfactorily accounted for, it was still possible that the lowest
might be due to the formation of a mixture of this class.

Commercial ether (70 grams) was fractionated with alcohol (20
grams) and water (10 grams), which formed a clear solution with
it at ordinary temperatures :

B.p.

Weight.

A.

34-06-34-16°

5-0

m

3416—34 24

14-1

175

34-24— 34-34

10-3

100

P,. p.

"Weight.

A.

34 34'

29-6

2960

Residue

29-0

—

Loss

12-0

—

There were here two maxima. These might conceivably have
indicated a ternary mixture, followed by the binary aqueous mix-
ture, but that this was impossible in presence of the very large
excess of alcohol. The alternative was that the upper maximum
was a duplicate or shadow (p. 1852) of the lower, due to the rapidly
increasing concentration of the alcohol in the still. Repetition
with a larger proportion of ether (160 grams) gave a much sharper
lower maximum (b. p. 34'19°, A 1460), and a lower boiling point
for the upper maximum (34'23°, A 2950); the two maxima were
evidently verging on coincidence. And on fractionating ether (50
grams) with much alcohol (36 grams) and little water (0"5 gram),
only two maxima were obtained: ether, b. p. 34"18°, A 1280; and
alcohol, b. p. 78-12— 78-18°, A 212. The two lower maxima had
coincided.

As the lowest maximum in each case was above the boiling point
of the binary aqueous mixture (34'15°), it was now practically
certain that it was due to the latter, the boiling point being raised,
as in the case of dry ether, by the excess of alcohol in the still.
This was finally established by refractionating the collective distil-

1854 WADE AND FINNEMORE: ETHYL ETHER. PART I.

lates from the first fractionation (58'0 grams) with water (200
grams) :

B. p.

Weight,

A.

34-0_34-14°

5-5

68

3415

42-8

7380

Residue

19-5

Loss

10-2

—

There was now only one maximum, identical with that of the
binary aqueous mixture. A ternary mixture would not have been
resolved by thus distilling with water.

Ether therefore does not form a ternary mixture with alcohol
and water.

As ether forms a binary mixture with water, which boils with
characteristic constancy 0'35° lower than the pure substance, and
contains enough water to saturate it at the ordinary temperature,
it follows that when moist ether is fractionated it will commence
to pass over at a rather lower temperature than pure ether; and
that unless all but a trace of the water is first removed, the pure
substance cannot be obtained from it by any process of distillation.
Further, as the boiling points both of ether and of its binary
mixture are raised by the presence of alcohol, the formation of a
maximum above the true boiling point from any particular specimen
is strong presumptive evidence of the presence of alcohol in that
specimen.

It may be concluded that, in order to obtain pure ether, it is
necessary, first, that the alcohol should be completely eliminated,
and then all but the merest trace of water ; from such a product
a good yield of anhydrous ether should then be procurable by
accurate fractionation. From these data, the authors have suc-
ceeded in devising processes which, as will have been noticed from
examples mentioned incidentally in the preceding pages, have
already furnished ether of a higher order of purity than any of
the specimens which they have treated by the older methods. As in
the case of chloroform, however, the problem is complicated by the
peculiar instability of the highly purified substance ; this has necessi-
tated yet further investigation, the results of which it is hoped to
communicate in the near future.

Chemical and Pharmaceutical LAnop.ATORiES,
Guy'.s Hospital, London, S.E,

I

HIBISCUS SABDARIFFA AND TIIESPASIA LAMPAS. 1855

CCV. — The Colouring Matters of f lie Flowers of IJihiscus
sahdariffa and Thespasia lampas.

By Arthur George Perkin.

Hibiscus sahdartffd.

The Hibiscus sabdariffa (Rozelle or Patwa), or Red Sorrel of the
West Indies, is a sniiall shrub whicli grows from three to four feet
high, and is widely cultivated throughout the hotter parts of India
and Ceylon. There is a considerable demand for this plant among
the natives of India, for in the North-West Provinces it is grown
as a food plant, and similarly in the Punjaub it is cultivated for
the sake of its succulent acid calyces. The stems yield the Rozelle
hemp of commerce, and this is obtained by retting the twigs as
soon as the plant is in flower (Watts, Diet, of Economic Products
of India, TV, 242). According to Burkill {A gricrdiiiral Ledger,
Gcdcutta, 1908, No. 2, 13), the Hibiscus sabdariffa has fleshy,
red calyces and pale yellow flowers. The yellow flowers are
just capable of dyeing yellow, but are not used at all in India
for this pvirpose; on the other hand, the red calyces are employed
for dyeing in a very obscure degree in two remote parts of the
country. Their use in Chutia Nagpur was made known by the
Rev. A. Campbell, and their use among the Shans by Leveson.

The sample employed in this investigation was kindly sent me
by the authorities of the Imperial Institute, and these flowers
included the stalk, epicaljrx, calyx, and corolla. Unfortunately,
however, the material had considerably deteriorated during trans-
port, for on arrival most of the flowers had suffered decoloration,
and the red colouring matter was now practically absent.

Experimental.

The material was digested with ten times its weight of boiling
water for six hours, the mixture filtered, and the residue well
pressed. The deep brown extract was treated with sulphuric acid
to the extent of 2 per cent., which caused it to become red coloured,
and the solution digested at the boiling point for two hours in
order to hydrolyse the glucosides present. As the liquid, on cooling,
had not deposited any colouring matter, it was extracted with a
large volume of ether — a very troublesome operation, because the
mixture emulsified, and the ethereal extract did not completely
separate until after several hours. The latter was removed,

1856 PERKI.V: THE COLOURING MATTERS OF THE FLOWERS OF

repeatedly washed with water, evaporated to dryness, and the
small quantity of brownish-yellow residue which thus remained was
digested with boiling water, and the next day the crude yellow
colouring matter was collected (the filtrate A being reserved for
further examination). The yield of this product was poor, as
500 grams of the flowers gave, on the average, only 1'8 grams of
the crude substance, and during the operations described below
this suffered a very considerable diminution.

For purification, the semi-crystalline substance was dissolved in
a large volume of boiling absolute alcohol, and the solution partly
evaporated. A small quantity of crystals thus separated, which
were collected and washed with alcohol (B), and a further trace
of this compound was usually deposited on distilling off more of
the alcohol. The alcoholic solution was now treated while hot
with a little boiling water, and the yellow product which separated
on cooling was collected and recrystallised from dilute alcohol.

As the complete purification of this compound, the main
colouring matter derived from the flowers, by further crystallisation
was not feasible, it was acetylated by a short digestion with boiling
acetic anhydride, to which a few drops of pyridine had been
added (Proc, 1908, 24, 150), and the product isolated by pre-
cipitation with water was crystallised from alcohol until colourless.

As thus obtained, it melted at 222 — 224°, and on analysis gave
C = 57*25; H = 4"23 per cent. To hydrolyse this product, it was
dissolved in acetic acid, a little sulphuric acid was added, the
solution boiled, and subsequently treated with water. The pale
yellow needles which separated gave, on analysis :

Found, C = 57-51; H = 3-49.

CjeHjoOg requires C = 57"83; H = 3'61 per cent.

It was, however, subsequently observed that when this apparently
pure acetyl compound was recrystallised twice from acetic acid
containing a little alcohol, its melting point rose to 229 — 230°, and
this, on analysis, gave slightly lower figures :

Found, 0 = 56-88; H = 419.

Ci5H40g(C2H30)g requires 0 = 56-84; H = 3-86 per cent.

By hydrolysis in the manner above-described, the amount of
colouring matter thus produced also agreed well with this formula :

Found, CijHioOs^ 55-93; 55-85.

C27H22OJ4 requires Ci5Hio08 = 55-79 per cent.

The free colouring matter, dried at 160°, gave the following
result :

Found, 0 = 56-60, 56-40; H = 3-37, 328.

OigHioOg requires 0 = 56-60; H = 3-14 per cent.

HIBISCUS SABDARIFFA AND THESPASIA LAMPAS. 1857

It consisted of pale yellow needles, which, after some time,
developed a green tint, and appeared to melt between 295° and 300°,
but the exact point was obscured by the darkening of the tube. It
dissolves in concentrated alkalis to form orange-red solutions, and
these, when diluted with water, become green coloured, and finally
dull brown. If a suspension of the colouring matter in water is
treated Avith one drop of the alkali, the green coloration is at once
produced, and this, by oxidation with the air, develops on the
surface a transient blue tint. With alcoholic lead acetate, it gives a
deep red precipitate, which, on boiling, becomes brown, and alcoholic
ferric chloride produces a deep olive-green liquid. Mineral acids,
in the presence of acetic acid, gave in the usual way orange-red,
crystalline compounds, but owing to the scarcity of material,
sufficient of these could not be produced for analysis.

By fusion with alkafi, for which but a very small quantity of
substance was available, a colourless, crystalline product was
obtained. This melted at 194 — 196°, gave with aqueous lead
acetate a colourless precipitate, with ferric chloride a deep green
coloration, and was thus evidently protocatechuic acid.

Dyeing experiments with this colouring matter, employing
mordanted wool, gave the following shades :

Aluminium. Tin. Chromium. Iron.

Pale orange-brown. Orange-red. Dull brown. Deep dull olive.

In the presence of chalk, the shade obtained with the aluminium
mordant is olive-yellow, a result which is probably due to a partial
oxidation either of the free colouring matter in the dye-bath, or of
the lake which is subsequently produced.

These results suggested that this colouring matter of the flowers
of the Hibiscus sahdariffa was gossypetin, a substance which exists
in the flowers of the Indian cotton plant, Gossypium herhaceum
(Trans., 1899, 75, 825), and a comparison of the two products
subsequently showed that this was the case. To gossypetin the
formula CigHjoOg was previously assigned, and the melting point
of its hexa-acetyl derivative was stated to be 222 — 224°. The
results given above, however, indicate that the true formula is
more probably CjsHjoOg, and that the original preparation from
the cotton flowers, of which very little was available for experiment,
was most likely contaminated with a trace of an analogous colour-
ing matter, containing a higher percentage of carbon, and, in fact,
there is evidence that such a compound also exists in minute
quantity in these Hibiscus flowers. To determine, if possible, the
identity of this substance, an examination of the mother liquors
obtained during the purification of acetylgossypetin was carried
out, and as a result a trace of a slightly more soluble acetyl

1858 PERKIN : THE COLOUIUNG MATfERS OF TUE FLOWERS OF

derivative was isolated, which melted almost entirely at 190 — 194°,
although it was evidently not quite pure. It is thus probable that
in addition to gossypetin a small quantity of quercetin is also
present in these flowers, and that the complete separation of these
substances is only effected when the admixture of their acetyl
derivatives is frequently crystallised from acetic acid. Pinally,
analyses of gossypetin obtained from Egyptian cotton flowers, the
examination of which is now in progress, have given results also
in harmony with the formula CijHjyOg.

Gossypetin is thus apparently isomeric with myricetin (Trans.,
1902, 81, 203), and there is a considerable resemblance between
these two substances as regards the colorations produced from them
by means of dilute alkali. On the other hand, hexa-acetylmyricetin
melts at 211 — 212°, and by fusion with alkali gives gallic acid.

The aqueous filtrate A (p. 1856) obtained during the isolation
of the crude colouring matter from these flowers was extracted
with ether, which removed a small quantity of a readily soluble
compound. This, after repeated crystallisation from water, formed
colourless needles, melting at 194 — 196°, which gave, with ferric
chloride, a green coloration, and consisted of protocatechuic acid.
It is possible that this compound may not exist in the fresh flowers,
and may be derived from protocatechualdehyde, for it is known
that the odour of certain flowers is due to the presence of the
latter substance.

As regards the sparingly soluble colouring matter (B) (p. 1856)
isolated with the gossypetin, and removed from it by fractional
crystallisation, the very small amount obtained admitted only of
a very cursory examination of its properties. It consisted of pale
yellow, glistening leaflets, which melted at about 340° Avith decom-
position, but the exact point could not be observed, owing to the
darkening of the tube. It does not contain a methoxy-group, does
not appear to form crystalline acid compounds with mineral acids,
and dissolves in alkalis with a yellow colour. On acetylation, it
gives a colourless, very sparingly soluble acetyl derivative, melting
at 238 — 239°, and it dyes mordanted calico. The analysis of this
compound, which appears to be an hitherto unknown colouring
matter, and for which the name hibiscetin is proposed, was carried
out, but the result is reserved, in the hope that it may be possible
later to obtain a large quantity of the flowers in a state of good
preservation, so that sufficient of this compound can be prepared
for a more thorough examination.

A search for hibiscetin in the sepals of the better known
Hibiscus rosa sinensis, for a supply of which I am much indebted
to Mr. Lawrence Balls, of the Khcdivial Agricultural Society at

HIBISCUS SABDAIUFFA AND THESPASIA LAMPAS. 1859

Cairo, was carried out with a negative result. This material
contained only the merest trace of yellow colouring matter^ which
it was ]iot possible to characterise, and in the flowers' calyces this
was, moreover, also practically absent.

Thespasia lampas.

The Thespasia lanipas is a small bush common to the tropical
jungles of India, Burma, and Ceylon. In Watt's Dictionaiij of the
Economic Products of India, there is no mention of the use of this
plant as a dyestuflf, but, on the other hand, the capsules and
flowers of the allied Thespasia jjoji^dnca are stated to give a yellow
dye, and this point has been corroborated by the late Sir Thomas
Wardle (Report on the Dyes and Tans of India). For the material
employed I am indebted to the authorities of the Imperial Institute :
this consisted entirely of the yellow sepals of the plant, which
in general appearance closely resembled those of the Gossypium
herhaccum. The quantity available for examination was small, and
had suffered partial decoloration.

The method employed for the isolation of the yellow colouring
matter, which is present in these flowers in the form of glucoside,
was identical with that found serviceable in the case of the
Hibiscus sahdariffa. Two hundred and fifty grams of the material
gave r5 grams of the crude dyestuff, and this was purified by
crystallisation from dilute alcohol, followed by conversion into its
acetyl compound. The latter consisted of long, colourless needles,
melting at 191—194°:

Found, C = 58-66; H = 4-12.

Ci5H50;(CoH30)5 requires C = 58-59; H = 3-90 per cent.

This compound possessed all the projjerties of acetylquercetin,
and the reactions of the free colouring matter, obtained as glisten-
ing, yellow needles, also indicated without doubt that it consisted
of quercetin.

Curiously enough, the aqueous filtrate obtained during the
isolation of the quercetin was found to contain protocatechuic acid,
which, as shown above, was also obtained from the Hibiscus
sahdariffa. It was identified by means of its melting point,
194 — 196°, and its characteristic reaction with ferric chloride.
Dyeing experiments with these flowers, employing mordanted
woollen cloth, gave fairly good shades, which do not, however, call
for special comment. They were in no way superior to the better
known Indian natural yellow dyestuffs, although locally they
might perhaps find useful employment. On the other hand, the
shades produced by the flowers of the Hibiscus sahdariffa were of a

1860 DAWSON AND LESLIE: DYNAMICS OF THE

much poorei" character, but this may possibly be accounted for by
the fact already alluded to, that the sample was of inferior quality,
and iu no way equal to the freshly gathered material.

Clothwokkers' Reseakch Laboratory,
The Univkhsity,
Leeds.

CCVI. — Dynamics of the Reaction hetiveen Iodine and

Acetone.

By Harry Medforth Dawson and May Sybil Leslie, M.Sc.

In the course of some measurements of the molecular solution
volume of iodine in various solvents, it was found that widely
divergent and abnormally low values were obtained in acetone
solution. For a freshly prepared solution the molecular solution
volume was much larger than that for a solution of the same
concentration which had been prepared for some hours. This
observation relative to the change in the volume of the dissolved
iodine was evidently connected with certain variations found in
the conductivity of acetone solutions of iodine. These variations,
originally observed during some experiments on the formation of
polyiodides of the alkali metals and substituted ammonium bases
in acetone, were not only obtained in the case of a pure iodine
solution, but also in that of solutions containing iodide and iodine.
In all cases the conductivity increased very considerably, and at
the ordinary temperature the change was soon completed. The
actual observations for a O'l molar solution of iodine may be
quoted. The specific conductivity at 18° of a solution made up
as quickly as possible was 4"5 x 10"^ mho; at the end of half an
hour the conductivity had increased to 57'0 x 10~^, and remained
constant at this value. At 0° the velocity of the change, which
could be readily followed by the position of the minimum on the
bridge wire of the conductivity circuit, was much smaller, and
about four hours were required before the equilibrium condition
was attained. The change in conductivity and in the volume of
the dissolved iodine was evidently due to the substituting action
of the iodine on the acetone, for the final solution was found to be
strongly acid, and the iodine titre had undergone considerable
diminution. For a solution of given concentration a definite end-
point appeared to be reached, indicating that the reaction involved
is reversible.

REACTION BETWEEN IODINE AND ACETONE. 1861

With the object of elucidating its nature, the reaction between
iodine and acetone has been investigated dynamically under vary-
ing conditions. To reduce the velocity the reacting substances were
dissolved in various solvents, of which water was the one chiefly
used. In the case of aqueous solutions, <;he dependence of the
velocity on the acetone and iodine concentrations and on the
acidity was determined. For convenience, the data obtained for
aqueous solutions will be considered first.

In all the experiments to be referred to, the conditions were
such that the acetone was in large excess relatively to the iodine,
so that the concentration of the acetone was practically constant
throughout the course of the reaction. If hydrogen ions are
present in moderate concentration, the reaction proceeds with
conveniently measurable velocity at the ordinary temperature. In
the absence of added acid, the initial velocity of the reaction is
very small, but since hydrogen iodide is formed as the reaction
proceeds, the velocity of the change gradually increases. When
the conditions are so chosen that the original concentration of
the hydrogen ions is not appreciably altered in consequence of the
gradual formation of hydrogen iodide, the experiments show that
the iodine disappears at a rate which remains constant from the
commencement until near the end of the change. The velocity
constant appears to be proportional to the concentration of the
acetone in the aqueous solution, and also to the concentration of
the acid.

The experiments from which these conclusions are drawn were
made at a temperature of 20°, which was maintained constant to
about 0'05°. Since iodine is only slightly soluble in dilute aqueous
solutions of acetone, it was found necessary to add potassivim iodide
in small quantity in order to obtain iodine solutions of sufliciently
large concentration. A known volume of freshly prepared solution,
contained in a stoppered flask in the thermostat, was acidified by
the addition of a definite volume of standard acid, and from time
to time measured portions of the solution were run into excess of
a dilute solution of sodium hydrogen carbonate, and the iodine
determined by means of sodium thiosulphate. If the acid solution
is not neutralised in this way before titration, the iodine cannot
be estimated, for the interaction of the added sodium thiosulphate
with the iodine results in the formation of increasing quantities
of iodide, and therefore of hydriodic acid, and this leads to a
reversion of the original reaction and the liberation of iodine.
In these circumstances, the blue colour of the solution returns
slowly after it has been discharged, and a definite end-point is
not reached until an amount of thiosulphate, approximately

VOL. XCV. 6 G

1862

DAWSON AND LESLIE : DYNAMICS OF THE

equivalent to the iodiue originally present in the solution, has been
added.

In table A, the data are recorded which were obtained in
experiments in which the acetone concentration was varied
between wide limits, and, further, those which show the influence
of the acid concentration on the velocity of the reaction. As
previously indicated, the iodine disappears at a constant rate in
accordance with the equation :

dx _ J

"57 -^ (1),

where x is the concentration of iodine after time t. If a represents
the original concentration of the iodine, we obtain for the integral
equation :

x = a-kt (2),

Under t are given the time intervals from the commencement of
the reaction in minutes, whilst a-j and Xo represent respectively
the experimental iodine concentrations (mols. per litre) and those
calculated from equation (2) by the aid of constants which are
indicated at the foot of each series of data. In all the solutions
examined, the concentration of the j^otassium iodide was 0'02 mol.
per litre :

Table A.

Experiment 1,

Acetone 5 grams per litre ; O'lA^-HoSOj

t. a;i.lOi a;2.10^

90 74-4 75-0

180 67-15 67-9

285 59-7 59-8

360 54-3 53-9

a;o = 0-00S2-0-0000078<.

Experiment 3.
Acetojie 60 grams per litre; 0"li\r-H2SO4.
t. Xi.lO-*. .r2.10^.

23 60-6 6"l-8

48 40-1 39-8

77 14-2 14-2

a-2=0-0082-0-000088<.

Experiment 5.
Acetone 5 grams per litre ; 1 'OiV^-HjSOj.
t. Xj.lO*. aro.lO^

29 57-5 58-2

50 41-0 41-0

81 19-9 15-6

X =0-0082-0 000082/:.

Experiment 2.
Acetone 15 '5 gramsper litre ;0'li\^-H2SO4

t.

Xj.lO^ a'^.lO".

30

70-7 71-4

92

56-7 57-2

191

34-7 34-7

236

24-4 24-4

261

18-9 18-7

309

7-7 7-8

^2

= 0-00782 -0-0000228<.

Experiment 4.

Acetonel20 grams per litre ;0-liV-H2SO4.

t. Xj.lO^ a-o.lO-*.

13-5 56-5 58-5

25-0 38-5 38-5

44-5 5-8 4-6

a;2 = 0-0082-0-000l74<.

Experiment 6.

Acetonel5'5gramsperlitre;0'5iV-H2SO4.

t. Xi-lO-*. x^-lO*.

10-5 66-0 66-0

26-5 470 47-5

36-5 360 35-9

56-5 13-5 12-7

.r„ = 0-00782-0-0001ie^

REACTION BETWEEN IODINE AND ACETONE. 1863

From the agreement between the values of x^ and Xo, it is clear
that the iodine disappears at a constant rate. This is certainly
true for the major part of the reaction, although experiments in
which the reaction was followed to near the end indicate that
the velocity diminishes considerably when the transformation is
nearly complete. For a given acetone solution this effect appears
to increase with the concentration of the acid present ; it is probably
connected with the reversibility of the reaction, an increase in
the acid concentration resulting in the liberation of a larger
proportion of hydriodic acid from the iodide present.

A comparison of the values of the velocity constant Ic in experi-
ments 1 to 4 shows that these are almost exactly proportional to
the concentration of the acetone. If the constant for the solution
containing 15'5 grams of acetone per litre is taken as basis, the
constants calculated on the assumption of proportionality are, for
the solutions containing 5, 60, and 120 grams per litre, respectively
0-00000735, 0-000088, and 0-000176, whereas the corresponding
experimental values are 0-0000078, 0-000088, and 0-000174.

In a similar way, a comparison of the values of k for experi-
ments 1 and 5 and for experiments 2 and 6, shows that the
velocity of the reaction is almost exactly proportional to the con-
centration of the sulphuric acid. If the activity of the acid is
due to the hydrogen ions, it follows from this that the catalytic
effect of the ions increases more rapidly than corresponds with
the increase in their concentration. A similar relationship has
been found in other reactions, in which acids act as catalysts.

In table B, the data obtained in experiments with hydrochloric
and acetic acids are recorded ; these experiments are comparable
with experiment 6 of table A, in which a solution containing an
equivalent amount of sulphuric acid was examined.

Table

B

Acetone 15-5 grams
0-5.V-HC1

per

litre ;

Acetone 15-5 grams per
0-5iV-CH3-CO,II.

litre ;

8-5 66-0
21-5 49-5
39-5 26-5
48-0 16-8

x,.10*.
67-1
50 0
26-5
15-3

t.

120
1100
1530
2640

ajj.lO-*,
76-5
62-6
55-7
39-2

Xo.lO^
76-45
62-0
55-7
39-4

x.,=0-00782-0-000131<.

a:., = 0-00782 - 0-00000147<.

From these data, it follows that the velocity constants for com-
parable solutions containing hydrochloric, sulphuric, and acetic
acids respectively in 0-5iy-concentration are in the ratio TSl, ri6,
0-0147. These numbers are approximately in the ratio of the
degrees of ionisation of the acids, and indicate that the observed

6 G 2

186* DAWSON AND LESLIE : DYNAMICS OF THE

catalytic influence is primarily due to the hydrogen ions. If we
assume that the catalytic effect in dilute acid solutions is propor-
tional to the concentration of the hydrogen ions, then from the
vahie of the constant for 0•5i^^-hydrochloric acid, which may be
regarded as ionised to the extent of 82 per cent., we obtain for
the rate of disappearance of iodine in an acidified aqueous solution
of acetone at 20°:

- — = ^ = 0-0012 ac.Co mols. litre/minute,
dt

Ci being the concentration of the acid in equivalents per litre,

a its degree of ionisation, and Co the concentration of the acetone

in mols. per litre.

Action of Iodine on Acetone in Neutral Solution.

In the absence of acid, the rate at which iodine reacts with
acetone is very small. Since, however, hydrogen iodide appears
as one of the products of the reaction, it follows that the reaction
velocity should increase as the reaction proceeds, in consequence
of the gradually increasing concentration of the hydrogen ions.
That this is the case is shown by the following experiment.

The quantity of potassium iodide required to give a 0'005 molar
solution was weighed out into a 500 c.c. flask, and in this was
placed a small quantity of water and excess of iodine. After
shaking until no more iodine dissolved, the solution was diluted,
and, after the addition of 25 c.c. of acetone, made up to 500 c.c.
The clear solution was then syphoned off from the undissolved
iodine, and placed in a thermostat at 20°. After measured time
intervals, the iodine concentration was determined by removing
50 c.c. of the solution to a flask containing about 50 c.c. of water,
5 c.c. of a 0'2i\^-sodium hydrogen carbonate solution, and about
0"5 gram of potassium iodide. Without the addition of potassium
iodide, a satisfactory end-point could not be obtained on titrating
with O'OLT-thiosulphate solution. This phenomenon, which nulli-
fied the first attempts to determine the progress of the reaction
in the absence of foreign acid, has not as yet received an explana-
tion. Table C contains the data for the above experiment. From
the values of the mean velocity during the successive time intervals,
it is evident that the velocity increases as the amount of iodine
in the solution diminishes. This auto-catalytic effect will, of
course, be also exhibited in solutions to which a foreign acid has
been added, provided that the ratio of the concentration of the
acid to that of the iodine at the commencement is not too large :

REACTION BETWEEN IODINE AND ACETONE.

1865

Table C.

Concentration of iodine,

Time. niols. per litre.

0 0 002088

24 hours 0-001892

46 ,, 0-001482

65 ,, 0-000596

Mean vclocitj',
niols. per litre per hour.

8-2xl0-«
18-6x10-8
46-6xl0-«

Influence of Tenvperature on the Rate of Change.

With tlie object of ascertaining the influence of temperature on
the rate of the reaction, comparative measurements were made
at 20° and 30°. For this purpose, a solution was used containing
8"83 grams of acetone and 0'2 gram-equivalent of sulphuric acid
per litre. In order to obtain the iodine in a sufficiently large
concentration, potassium iodide was added to give a 0"02 molar
solution. The results of these measurements are recorded in exactly
the same way as in table A :

Table D.

Temperature =

= 20'

Temperature =

^30'.

t.

x^.\0\

.XV 10^.

t.

a;,.10*.

a-2.10*

29

73-5

7*2 -4

24

61-75

61-4

70

60-75

61-55

55

37-0

37-2

92

55-55

55-7

77

20-0

20-1

112

51-25

50-4

97-5

5-6

4-1

138

44-0
= 0-00801 -0-0

0002

43-55
65)!.

CCs

= 0-00801 -0-00()078<.

It is evident from this table that the reaction proceeds with
constant velocity at 30° in the same way as at 20°, and that for
a rise of 10° the velocity increases in the ratio 78/26-5=2-95. The
reaction has therefore a temperature-coefficient which may be
considered to be normal.

Action of Iodine on Acetone in N on-aqueous Solvents.

When liquids other than water are used to dilute the acetone,
with the object of reducing its active mass, and thereby diminish-
ing the velocity of the change, the phenomena which are met with
differ very greatly from those observed in the case of aqueous
solutions of acetone. As the result of preliminary experiments
with solutions of acetone in carbon tetrachloride, methyl alcohol,
methyl acetate, benzene, and nitrobenzene, it was found that in
these cases the action of the iodine on the acetone is much less
complete as compared with the action in a corresponding aqueous
solution.

Equal quantities of iodine (050 gram) were weighed out into

1866

DAWSON AND LESLIE: DYNAMICS OF THE

a scries of stoppered bottles, each containing 50 c.c. of one of the
above solvents. After shaking to bring the iodine into solution,
5 c.c. of acetone were added to each bottle. The solutions were
titrated at the end of twenty-four hours, in which time, as sub-
sequent titrations showed, the reaction had reached a limit. The
extent to which the reaction jDrocceds in the different solvents is
shown by the percentage amounts of unchanged iodine, which
Avere as follows : Carbon tetrachloride 72, benzene 72, methyl
acetate 62, nitrobenzene 57, and methyl alcohol 47 per cent. The
incompleteness of the reaction in these cases is in marked contrast
to the behaviour of a corresponding aqueous solution. On making
an exactly similar experiment with an aqueous acetone solution,
which was made slightly acid so that the end-point would be
reached more quickly, it was foiind that the percentage of un-
changed iodine was only 0'35 per cent. From these results it is
evident that in aqueous solution the reaction between iodine and
acetone takes place much more completely than it does when other
liquids are used as solvent media.

Another point of difference is presented by the much greater
velocity with which the reaction appears to take place in the non-
aqueous solvents as compared with the velocity in neutral aqueous
solution. With the object of obtaining information relative
to the influence of the solvent on the velocity of the change, com-
parative measurements were made in which carbon tetrachloride,
benzene, nitrobenzene, and methyl alcohol were employed as
solvents.

Solutions containing 10 per cent, by volume of acetone and about
004 mol. of iodine per litre were used. In the estimation of the
unchanged iodine, the pipetted fraction of solution was run into
a bottle containing about 250 c.c. of water and 10 c.c. of a
O'li\^-sodium hydrogen carbonate solution, the contents being
shaken violently after each addition of thiosulphate solution. The
velocity of the reaction in the different solutions is deducible from
the data in table E, which gives the number of c.c. of a 0'01i\^-sodium

Table

E.

Carbon

tetrachloride.

Benzene.

Nitrobenzene.

Methyl alcohol.

^

C.c. of

C.c. of

C.c. of

C.c. of

Time.

NajSjOg.

Time.

NasSjOj.

Time.

Na^S^Og.

Time.

NaoS.^O.,.

0-0

39 0

0-0

—

0-0

36-1

0-0

37-6

64-5

38-6

4-5

38-9

8-0

35-6

7-0

33 P

81-5

37-8

24-0

38-2

26 5

32-5

17-5.

28-75

94 5

36-75

44 0

37-2

.38-0

27-75

25-5

24-0

107-0

35-65

57-5

35-4

49-0

23-2

34-5

18-7

1190

33-25

68-5

31-6

128-5

28-65

REACTION BETWEEN IODINE AND ACETONE.

1867

thiosulphate solution required by 5 c.c. of the acetone -iodine solu-
tion after the time intervals indicated in minutes.

The differences caused by the variation of the solvent are best
seen from the figure, in which curves are drawn through the
points obtained by plotting iodine concentrations against the time
intervals. From the relative positions of the curves, it is evident
tliat the velocity of the reaction increases with the solvent in the
order — carbon tetrachloride, benzene, nitrobenzene, methyl alcohol.
In all cases, the slope of the curve towards the axis of abscissa?
increases as the reaction progresses, which seems to indicate that
there is an autocatalytic effect similar to that found in the case

46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16

liiiU^^

^ \

1

Crr

^■r^^t.^

^^

~— 4

?~-

■^

J^'

-«c

\,

"

JO^

^4-

-^

^

\

\

-7.

^

s

\

»*^

V

\

\

s

1

\.*

^,

\

\

L

%-

'

^

\

Y^

\

o

\1^

\

Y^

\

\^

\

Tl

TTIC

3

5

7

0

1

05

14{

minutes

B,atc of action of iodine on (Ketone in different solvents.

of aqueous solutions. On the same diagram the behaviour of an
aqueous solution containing the same amount of iodine would be
represented by a straight line parallel to the abscissae; in other
words, the initial velocity of the reaction in neutral aqueous
solution is so small that no measurable change in the iodine con-
centration takes place by the time the reaction in the other solvents
has come to an end. The position of the water curve on the
diagram is not what would have been anticipated on the basis
of the results obtained with the other four solvents. From the
order in which these arrange themselves, it might indeed be expected
that the velocity in water would be greater than in methyl alcohol.

1868 DAWSON AND LESLIE : DYNAMICS OF THE

That it is so very much smaller is probably due to differences in
the mechanism of the change in the different solvents.

The factors which influence the velocity of the reaction in the
case of non-aqueous solutions have not been ascertained, and it is
therefore not possible to discuss the mechanism of the reaction
under these conditions. On the other hand, the experiments on
aqueous solutions are sufficiently complete to show that the relation-
ships involved in this case are practically the same as those found
by Lapworth (Trans., 1904, 85, 30) for the action of bromine on
acetone in aqueous solution. Furthermore, Lapworth's view that
the reaction between halogen and acetone takes place in two stages
appears to afford a simple explanation of the observed facts.

Since the rate at which the iodine disappears is independent of
its concentration, the particular reaction which determines the
observed velocity of change is one in which iodine is not directly
involved. This reaction, according to Lapworth, is the trans-
formation of the ketonic form of acetone into the enolic form, and
this is accelerated by acids. In the second stage, the iodine reacts
with the enolic acetone, and the velocity with which this takes
place is relatively so large that this stage in the complete reaction
is practically without influence on the rate at which the iodine
disappears. This theory explains the observed fact that the
velocity is unaltered by the addition of potassium iodide, even
when the quantity added reduces the concentration of the free
iodine, as a consequence of polyiodide formation, to about one-
fiftieth of the concentration in the iodide free solution. It is also
consistent with the observed proportionality between the velocity
of the change and the acetone concentration, for the rate of
formation of the enolic acetone must be proportional to the con-
centration of the ketonic form, and this is practically identical with
the total acetone concentration.

If the isomeric change in question is the factor which determines
the rate at which acetone is acted on by all the halogens, then
the observed velocities should be the same for chlorine, bromine,
and iodine under comparable conditions. Lapworth has shown that
this is the case for bromine and chlorine, although chlorine was
found to act more rapidly at the commencement of the reaction
when the concentration of the halogen was greatest. To test the
theory further, we have compared the velocities in the case of
iodine and bromine. For this purpose, we determined the velocity
in a solution containing 15 '5 grams of acetone, O'l gram-equivalent
of sulphuric acid, 0"02 mol. of potassium bromide, and 0"008 mol.
of bromine per litre. This solution is strictly comparable with the

REACTION BETWEEN IODINE AND ACETONE. 1869

iodine solution of experiment 2, table A, for -whicli the constant 7c
is 0'0000228, whereas that found for the bromine solution is
0'0000260. Although perhaps a closer agreement between the two
constants might have been expected, the extent of the deviation —
about 6 per cent, from the mean value — cannot be considered large
enough to invalidate the theory. It is probable that the observed
difference is due to secondary factors, the nature of which might
be put in evidence by a detailed comparison of the velocities of
the two reactions.

Whilst the experimental data thus indicate that the mechanism
of the reaction is the same for the different halogens, the behaviour
of iodine is to some extent different, in that the reaction
in certain circumstances is reversible. Although no attempt has
been made in this pajDer to determine the exact nature of the
equilibrium relationships, certain observations connected with the
reversibility of the change may be recorded.

On passing hydrogen iodide into an acidified aqueous solution,
from which the iodine originally present had almost completely
disappeared, iodine was at once set free in considerable quantity.
The same result was obtained when iodoacetone, prepared by
the action of potassium iodide on chloroacetone (Scholl and
Matthaiopoulos, Ber., 1896, 29, 1550), was dissolved in acetone and
subjected to the action of hydrogen iodide.

Although these observations demonstrate the reversibility of the
change, it should be noted that the reaction proceeds practically
to completion under the conditions of the dynamic experiments in
tables A to D. If, however, the quantity of iodine which is added
to a given aqueous solution of acetone is increased, a gradually
increasing proportion remains unchanged at the end of the reaction.
In some qualitative experiments, it was found, for instance, that
when a gram-molecule of acetone dissolved in a litre of water
is brought in contact with O'Ol or 0*02 gram-molecule of iodine,
the resulting solution is nearly colourless, whereas with 0"04 gram-
molecule of iodine an appreciable proportion of the latter
remains unacted on when the end-point is reached. These facta
serve to emphasise the difference between aqueous and non-
aqueous solutions in regard to the extent to which the reaction
proceeds. In pure acetone the equilibrium relationships are similar
to those in non-aqueous solutions, as may be seen from the fact
that in a 0"02 molar solution the reaction comes to an end when
about 45 per cent, of the iodine has been transformed. Taken in
conjunction with the observation that the velocity of the reaction
in neutral aqueous solution appears to be very much smaller than

1870 BAUDISCH, HIBBERT, AND PERKIN :

the velocity in non-aqueous solutions, the differences in behaviour
siiggest that the mechanism of the change in the two cases is
different. It is hoped that further experiments may decide whether
this is the case or not.

The Univeusitt,
Leeds.

CCVII. — The Reduction of 4k-Hydroxy-o-toluic Acid.

By OscAU Baudiscii, Gilbert Stanley Hibbert, and
William Henry Perkin, jun.

The experiment.s on the synthesis of the terpenes which have been
carried out in these laboratories during the last few years are based
on the preparation, in the first instance, of an unsaturated acid, the
ester of which, when treated with magnesium methyl iodide, yields
the corresponding terpineol, from which, by the action of dehydrating
agents, the terpene is obtained in the usual manner. Thus, for
example, terpineol and dipentene were synthesised according to the
scheme :

CHMe<^^~^^2>CH-C02H -^ CHMe<^]^~^^2>CH-CMe2-OH

l-Methyl-A^-cycZohexene- Terpineol.

4-carboxylic acid.

CHMe<^Jj[~^^2>cH-CMe:CH2

Dipentene,

Several other unsaturated acids have already been synthesised and
converted successfully into the corresponding terpineols and terpenes
by a similar series of reactions. In continuing these researches, the
object which has more particularly been kept in view has been the
synthesis of unknown members of the ortho- and meta- series of the
terpene group, but the great difficulty throughout has been the
problem of discovering methods for the preparation of the requisite
unsaturated acids, especially in quantities sufficient for subsequent
investigation. The three communications now submitted contain an
account of the first portion of an investigation undertaken with the
object of preparing a new series of methylci/c^ohexenecarboxylic acids
(t^trahydrotoluic acids) for the purpose of subsequent use in the
synthesis of terpenes and their derivatives. The proces.ses employed
in all the cases are similar, and may therefore be well illustrated by a
single example.

In the present communication, the starting point is 4-hydroxy-o-

THE REDUCTION OF 4-HYDROXV-O-TOLUIC ACID. 1871

toluic acid (I), which is reduced by sodium and alcohol to \-methi/lcjclo-
hexan-i-ol-2-carhoxijlic acid (II). The next step is to convert this
into the corresponding iromo-acid (III), and from this, by elimination
of hydrogen bromide, to obtain two \-inethylcyc\ohexenecarboxylic acids
(IV and V) :

(I.) (11.)

(IV.)

^CHMe<g«^C^jj);^?H>CH

\

CHMe<gge^Q^jj^.gH^>CHBr ^

'^CHMe<^5,---CH,^^jj

(V.)

from each of which, by the action of magnesium methyl iodide and
then of dehydrating agents, the corresponding ortho-terpineols and
ortho-terpenes should result in the usual manner.

This method of synthesis has, however, its limitations, because not
all hydroxytoluic acids can be reduced to the corresponding hexahydro-
acids by sodium and alcohol. In a previous communication (Trans.,
1907, 91, 482), it is shown that m-hydroxybenzoic acid readily yields
the corresponding hexahydro-derivative when it is reduced by sodium
and alcohol (compare Einhorn, Anncden, 1896, 291, 298), but
repeated experiments which we have made under a variety of conditions
have convinced us that ^>hydroxybenzoic acid is not appreciably
changed when it is boiled either in ethyl- or amyl-alcoholic solution
with sodium, and we have found that 6-hydroxy-m-toluic acid,

Me

is also not reduced under these conditions (compare p. 1893).

It seems therefore probable that other hydroxy-acids which contain
the hydroxyl group in the para-position with respect to the carboxyl
group will, in genei-al, be found to exhibit similar resistance to this
reducing agent. Some years ago, Einhorn and Lumsden {Annalen,
1894, 280, 260) showed that, when salicylic acid is reduced by
sodium and alcohol, fission of the ring takes place with formation of
n-pimelic acid, a change which is probably represented thus :

and a similar behaviour is exhibited by other o- hydroxy-acids of the

1872 BA.UDISCH, HIBBERT, AND PERKIN :

aromatic series. There is thus reason to believe that the only
aromatic hydroxy-acids which can be reduced to the corresponding
hexahydro-derivatives by sodium and alcohol are those in which the
hydroxy-group and carboxy-group occupy the meta-position with
respect to one another.

If this be true, it is easily seen that in the toluic acid series only
four acids are available for reduction, namely :

I. From o-toluic acid, the two acids,

^le HO Me

/^ \cO2H and <^ ^C02H.
HO^ ~

II. From ??i-toluic acid, the acid of the formula

Me

HO

>C02H.

III. From p-toluic acid, the acid

Hq_

Me<^ ^COgH,

and the reduction of this acid by alcohol and sodium has already
been the subject of a careful investigation (Meldrum and Perkin,
Trans., 1908, 93, 1417).

The experiments described in this and the two following communi-
cations show that, as was to be expected, all the above m-hydroxy-
acids may be reduced with comparative ease by sodium and alcohol,
and a detailed description is given of the various hydroxy-acids
which are obtained in this way. Experiments on the conversion of
these hydroxy-acids into the corresponding uusaturated acids and into
the terpineols and terpenes have been commenced, and will form the
subject of future communications.

The present communication deals with the reduction of ^-hydroxy-
o-toluic acid,

/^\C02H.

HO
This acid seems to have been first prepared by Jacobsen (Ber., 1881,
14, 41), who obtained it from 4-sulphamino-o-toluic acid by fusion
with potassium hydroxide, and subsequently {Be7\, 1884, 17, 163) by
treating 4-amino-o-toluic acid with nitrous acid, and he states that it
melts at 172°. More recently a number of patents have been taken out
which show that this acid may be obtained from certain derivatives of

THE REDUCTION OF 4-HYDROXY-O-TOLUlC ACID. 1873

naphthalene by a remarkable decomposition due to the action of fused
alkali. Kalle & Co. (D.R.-P. 91201, Friedlander, Fortschrilte der
Teerfarhenfahrikation, IV, 148) show that it is formed from naphthalene-
1:3: 7-trisuIphonic acid, l-naphthylaniine-3 : 7-disulphonic acid, and
8-amino-2-naphthol-6-su]phonic acid by fusion with potassium
hydroxide at 260°. The Farbwerke vorm. Meister, Lucius k Briining
(D.R.-P. 81281 and 81333, Friedlander, ibid., IV, 149—150)
obtained the same acid from 2-naphthylamine 6 : 8-disulphonic acid
or 2-naphthol-6 : 8-disulphonic acid ((z-acid) by fusion with sodium
hydroxide at 260 — 320°. All these naphthalene derivatives contain
the substituent groups in the positions marked by asterisks in the
formula,

*

and the remarkable process of I'eduction and oxidation caused by the
fusion with alkali hydroxide at the high temperature employed may
be illustrated in the case of 6^-acid :

OH CO2H/ \0H

-^ CH3I i •

The yield obtained from 6^-acid is remarkably good, and most of the
4-hydroxy-o-toluic acid required for this investigation was prepared
from (z-acid by fusion with sodium hydroxide under the conditions
described on p. 1875. When quite pure it melts at 183°, and not at
172° as stated by Jacobsen (loc. cit.).

4-Hydroxy-o-toluic acid is reduced by sodium and alcohol with
some difficulty, and is converted into a mixture of hydroxy-acids,
from which all the four possible isomerides (two cis- and two trans-)
have been isolated in a pure condition.

The two cis-l-methylcyclohexan-4:-ol-2-carboxi/lic acids,
H. /Me Me. /H

\c/ \c/

CHoH'C-CO,H , CHoH-C-COoH

I 2 I 2 and I -^ I ^

CH, CHo CH, GIL

h/ "^oh h^ \oh

melt at 191° and 126 — 128° respectively, and, as it has not been
found possible to determine with which of the above formulae each of
these acids corresponds, they have been named cis-(A) (in. p. 191°) and
ciV(B) (m. p. 126 — 128°). The ci8-{A) acid decomposes at its melting

1874 BAUDISCH, HIBBERT, AND PERKIN :

point into steam and an oil, but, unfortunately, owing to the small
amount of material available, we have not been able to determine the
nature of the lactone or unsaturated acid which is produced as the
result of this decomposition. The c{s-{B) acid decomposes at about 160°
into steam and a lactone, which distils at 130 — 135°/20 mm., and is
converted into the cis-(B) acid on dissolution in alkali hydroxide.

Both the c/s-(A) and the cis-{B) acids yield the corresponding bromo-
acids when treated with fuming hydrobromic acid, but whereas
cis-{Aybromo-l-methylcyc\ohexane-2carboxi/lic acid is crystalline and
melts at 103 — 105°, the corresponding cis-(B)-5ro??to-acid is a syrup.

The two tra,iis-l-methylcjelohexan-i-ol-2-ca7-boxi/lic acids,

H. /Me Me, ,H

/ \

' ^ I ^ and I - ' - '

oh/ ^h oh/ ^H

melt at 163 — 165° and 122 — 123° respectively, and differ from the
cz's-acids in the fact that they do not decompose with elimination of
steam until about 220°. In this case, also, we have no evidence to show
with which of the above formulae each of these irans-acids corresponds,
and we have therefore named the acid of melting point 163 — 165°
<ra?is-(A), and the acid of melting point 122 — 123°, irans-{W).

These two acids are converted into the corresponding 6romo-acids
when they are heated with hydrobromic acid, and the esters of these
acids, as also the esters of the cis-bromo-acids, yield, on heating
with diethylaniline, unsaturated esters, which are at present under
investigation.

During the reduction of 4-hydroxy-o-toluic acid with sodium and
alcohol, there is always formed, sometimes in considei^able quantities,
an unsaturated acid, CgH^gOs, which readily yields a beautifully
crystalline lactone (m. p. 44°) at the ordinary temperature, and this
passes over when the product of reduction is distilled in a current of
steam.

There can be little doubt that this unsaturated acid is an inter-
mediate step in the reduction of 4-hydroxy-o-toluic acid, and is
converted, by the further action of the sodium and alcohol, into the
1 -methylc?/c^ohexan-4-ol-2-cai-boxylic acids.

The behaviour of the acid towards permanganate shows that it is
un.saturated, and this is confirmed by the fact that the lactone i-eacts
with fuming hydrobromic acid with formation of a tZiftrowio-acid,

THE REDUCTION OF 4-HYDROXY-O-rOLUIC ACID. 1875

CgHj.,0.,Br„, a crystalline substance (m. p. 158 — 160°), which is decora-
posed by cold sodium carbonate with elimination of carbon dioxide
and separation of a heavy neutral oil containing bromine.

The ease with which the hydroxy-acid, CgHj.^Og, is converted into
the lactone seems to indicate clearly that it is a y-hydroxy-acid
possessing one of the formulae :

1 -Methyl- A''-cv/';/ohe.xen-4-ol- l-Methyl-A^-cj/cWiexen-i-ol-

2-c'arboxylic Acid. 2-carboxylic Acid.

and, of these, the former is to be preferred.

^ The fact that the dibromo-derivative, CgHj202Br2, readily loses
carbon dioxide and yields a neutral brominated oil when it is treated
with sodium carbonate at the ordinary temperature, recalls the similar
behaviour observed in the case of the /3-halogen derivatives of phenyl-
propionic acid, CgH-'CHX'CH.^'CO.^H, which are decomposed by cold
sodium carbonate with elimination of carbon dioxide and formation of
styrene. It is therefore probable- that one of the bromine atoms
in the bromo-derivative, CgHjgOgBr.,, occupies the /^-position in rela-
tion to the carboxyl group, and, as the second bromine atom, owing to
the acid, (J^H-^^O.^, being derived from 4-hydroxy-o-toluic acid, must
occupy the 4-position, the constitution of the dibromo-derivative is, in
all probability,

We assume, therefore, that the hydroxy-acid, CgH^o^g, and its
lactone have the constitutions represented by the formulae :

C«^<cS(0i^.CH?C«-C0^H and CH,<gH:CMe>cH. CO

I O

respectively.

Preparation and Reduction of A^-Hydroxy-o-toluic Acid.

In preparing this acid, sodium 2-naphthol-6 : 8-disulphonate,* in
quantities of 1 "5 kilos., was fused with sodium hydroxide (3 kilos.)
and water (3 kilos.) in an autoclave of 6 litres capacity at 260 — 280°
for twelve hours. The product was diluted with half its volume of
water, acidified with hydrochloric acid, and the crude 4-hydroxy-o-
toluic acid collected and washed with a little water. The mass was
then dissolved in a slight excess of hot sodium carbonate, filtered, and
again acidified, when the acid separated in almost colourless crystals,

* We wish to express our thauks to Messrs. Cassella & Co. for kindly supplying
us with a large (quantity of this salt.

1876 BAUDISCH, HIBBERT, AND PERKIN :

and, after once crystallising from water, it was quite pure and melted
at 183°. The yield obtained was about 380 grams.

The reduction was carried out under the following conditions : The
pure acid (100 grams) was dissolved in pure ethyl alcohol* (2 litres)
in a 10-liti'e fla-^k connected with a very long and very efficient reflux
condenser, to the end of which a condenser sloping downwards was
attached. . The sodium (300 grams), in pieces as large as could con-
veniently be put into the flask, was introduced all at once, when the
alcohol soon began to boil and was carried over in quantities by the
vigorous evolution of hydrogen. Most of it condensed and ran back
into the flask, and the remainder was condensed by the downward
condenser and collected in a large flask kept cool by running water.
When the action had moderated, the distilled alcohol was poured
back, and, as soon as the sodium showed signs of solidifying, the flask
was shaken vigorously and the action allowed to proceed, if necessary
with the addition of small quantities of hot alcohol, until the sodium
had almost disappeared.

A mixture of alcohol and water was then cautiously added, and then
enough water to dissolve the sodium salt ; the solution was then
allowed to cool, nearly neutralised by the addition of hydrochloric
acid, and the alcohol distilled olf from a salt-solution bath. The
residue was acidified with excess of hydrochloric acid, when a syrup
separated, which was extracted three times with ether, the ethereal
solution washed with a little water, very thoroughly dried, the ether
distilled off, and the residue again reduced under the same conditions
as before. The acid from the second reduction was now distilled in
steam, in order to remove as much as possible of an unsaturated
lactone (A, p. 1881). The residue was again extracted, and the crude
mixture of hydroxy-acids esterified by digesting, in quantities of
100 grams, with absolute alcohol (300 c.c.) and sulphuric acid (20 c.c.)
on a reflux apparatus for six hours. The product was diluted with
water, extracted with ether, the ethereal solution well washed with
water and dilute sodium carbonate, evaporated, and the residue
fractionated under 15 mm. pressure, when a large quantity of a viscid
oil (60 — 70 grams) passed over below 180°, leaving a dark residue in
the flask, which was not further examined. After two further
fractionations, the bulk of the oil (55 grams) distilled at 150 — 160°/
15 mm., and this was mixed with a moderately concentrated solution
of potassium hydroxide (35 grams) in methyl alcohol and left at the

* Experience has shown that it is a matter of great importance, in reductions of
tills kind, that the alcohol shall be as anhydrous as possible, as even the presence of
half a per cent, of water retards reduction in a quite unexpected manner and some-
times entirely prevents it. The "absolute" alcohol employed in these experiments
was distilled over calcium before use.

THE REDUCTION OF 4-HYDK()XY-0-TOLUIC ACID. 187 7

ordinary temperature overnight. The product was diluted with
water, unhydrolysed ester [A, 8 grams) extracted with ether, the
aqueous solution saturated with carbon dioxide, evaporated until free
from methyl alcohol, acidified, and extracted four times with pure
ether (B) and then a further eight times on the machine (C).

The extract, B, was evaporated and the viscid oil placed over
sulphuric acid for some weeks ; the semi-solid mass was then left
in contact with porous porcelain until the oily impurity had been
completely removed. When the colourless mass was systematically
crystallised from water, it was separated with some considerable
difficulty into two acids, namely, trans{A)- and (;;s(A)-l-me tliylcyc/o-
hexan-4-ol-2-carboxylic acids, melting at 163 — 165° and I'JO — 191'^
respectively.

The ethereal extract (C) yielded, on evaporation, a syrup (5 grams),
which rapidly crystallised, and, after contact with porous porcelain,
the colourless mass separated from water in bunches of colourless
prisms, melting at 190 — 191°, and consisting of pure cis(A)-l-me^A?/^-
cyc\ohexan-4:-ol-2-carboxyliG acid. The oster (yl), which had escaped
hydrolysis in the cold, was hydrolysed by digesting with excess of
methyl-alcoholic potassium hydroxide on the water-bath, and yielded
a viscid syrup, which gradually crystallised. After remaining in
contact with porous porcelain, the residue was several times recrystal-
lised from ether, when a small quantity of an acid was obtained,
which melted at 190 — 191° and proved to be ci6(A)-acid.

The mother liquors were evaporated, and the semi-solid mass again
transferred to porous porcelain until quite dry and free from oil.

When the residue was systematically crystallised from ether, it
yielded, besides a little cis(A)-acid, a relatively large quantity of an
acid, which separated from ether in thin crusts, like paper, and from
water in hard, chalky crusts. This acid melts at 122 — -123°, and has
been named ira,n&{^)-\-methylcyc\ohexan-i-ol-2-carboxylic acid. This
partial hydrolysis experiment, which has been several times repeated,
indicates that of the three acids mentioned, the ester of the trans[\.)-
acid is the most readily hydrolysed in the cold, and that of the esters
of the cis(A)- and irrtns(B)-acids, the latter is hydrolysed with more
difficulty than the former.

iv?iXi&(^k)-\-Melhylcyc\oIiexan-4:-ol-'2-carboxylic acid melts at 163 — 165°
without decomposition, and its decomposing point appears to be
approximately 220 — 225°. It is sparingly soluble in ether, but
apparently more readily so than the cis(A)-acid, and separates from
this solvent in hard, glistening crusts :

0-1386 gave 0-3080 C0.2 and 0-1 140 HjO. C = 60-8; H = 9-l.

0-1518 „ 0-3388 CO.3 „ 0-1232 HgO. C = 60-8 ; H = 9-0.
CgHj^Og requires C = 60-8; H = 8-8 per cent.

VOL. XCV. 6 H

1878 BAUDISCH, HIBBERT, AND PERKIN :

The basicity, determined by titration with iV/10-sodium hydroxide,
gave the following result : 0*2062 neutralised 0'0521 NaOH, whereas
this amount of a monobasic acid, CgHj^Og, should neutralii^e
0 0522 NaOH.

This acid dissolves in hydrobromic acid (saturated at 0°), and the
solution remains clear for many hours, but, when heated on the water-
bath, it clouds, and in a short time an oily layer separates on the
surface of the hydrobromic acid. After the addition of water, the
heavy oil was extracted with ether, the ethereal solution washed, well
dried, and carefully evaporated, and, after remaining for two hours
over sulphuric acid in a vacuum desiccator, the syrup yielded, on
analysis, numbers which showed that it was nearly pure trans(A)-4-
bromoA-methylcycXohexane-l-carboxijlic acid :

0-1787 gave 0-1482 AgBr. Br = 35-2.

CgHjgOoBr requires Br = 36-2 per cent.

When the <7'ans(A)-hydroxy-acid (4-3 grams) was oxidised by
potassium dicbromate (2-8 grams), sulphuric acid (5 grams), and
water (50 c.c), a considerable quantity of unchanged acid was
recovered, but no trace of keto acid could be isolated.

trans(B) - 1 - Methylcyclohexan -4:- ol - 2 - carboxylic acid melts at
122—123°:

0-1216 gave 0-2712 COg and 00984 H^O. C = 60-8j H = 8-9.
CgHj^Og requires C = 60-8 ; H = S'S per cent.

It is rather sparingly soluble in ether, from which it separates in
curious, characteristic,, brittle crusts, like paper or egg shell.

From water, in which it is readily soluble, it separates in hard,
chalky crusts. When heated in a capillary tube, no decomposition is
observed until about 195°, when gas is very slowly disengaged, and
even at 215° the decomposition is not rapid. The melting point of
this acid (123°) is practically the same as that of the cjs-B-acid (p. 1880),
but when equal quantities of the two acids are mixed, the mixture
softens at 90° and is almost melted at 105°.

ciH{A-)-\-3Iethi/lcjc\o?texan-4:-ol-2-carboxyHc acid melts at 190 — 121°
with decomposition, and, if rather slowly heated, it decomposes below
this temperature :

0-1 140 gave 0-2530 COo and 0-0930 HgO. C = 60-5 ; H = 9-0.
CgHj^Og requires C = 60-8 ; H = 8-8 per cent.

On titration with iA710-sodium hydroxide, 0-2071 neutralised 0-0524
NaOH, whereas this amount of a monobasic acid, C^Hj^Og, should
neutralise 0*0524 NaOH. This acid is very sparingly soluble in cold
dry ether, but dissolves much more readily in the boiling solvent, and,
if the solution is concentrated, the acid separates after some time as a
crust of small, glistening prisms. It dissolves moderately readily

THE REDUCTION OF 4-HYDROXY-O-TOLUIC ACID. 1879

in hot water, and crystallises, on cooling, in beautiful, glistening
bunches of prisms. The finely powdered acid dissolves readily in
hydrobromic acid (saturated at 0°), and, after several hours, stellate
groups of crystals appear. These were collected, drained on porous
porcelain, and left over solid potassium hydroxide in a vacuum
desiccator until dry, but, owing to its being rather unstable, no
attempt was made to recrystallise the small amount of substance at
our disposal :

0-0890 gave 00765 AgBr. Br = 36-5.

CylljgOjBr requires Br = 362 per cent.

cis{A.)-4:-Bro77io-l-7nethi/lcyclohexane-2-carboxi/lic acid melts at about
103 — 105°, and dissolves readily in dilute sodium carbonate; when
warmed with silver nitrate and nitric acid, it gives an immediate
precipitate of silver bromide.

cis[B)-l-Me(h7/Icyc\ohexan-4:-ol-'2carboxi/lic Acid and its Lactone.

The porous plates which had beeen used in the purification of the
acids described in the last section were broken up, extracted with
ether in a Soxhlet apparatus, the ethereal solution evaporated, and
the residue distilled under 15 mm. pressure, when a considerable
quantity of oil passed over at 135 — 145° and most of the remainder at
185—195° (A).

On refractionating the lower boiling portion, most of it distilled at
126°/15 mm., and this was found on analysis and examination to
consist of the lactone of cis(B)-l-methi/lcyc\ohexan-4:-ol-2-carboxylic acid
mixed with a large proportion of the lactone of l-methyl-^'^-cyclohexen-
i-ol-2-ca7'boxylic acid (p. 1881).

In order to separate these two lactones, advantage was taken of
the fact that the latter acid is slowly converted into the Lictone
at the ordinary temperature, whereas the former acid is stable under
these conditions. The mixed lactones were dissolved in warm
dilute potassium hydroxide, cooled well, acidified, and left for seven
days, during which time the oily precipitate gradually became less
viscid and ultimately comparatively mobile. The whole was several
times extracted with ether, the ethereal solution well washed
with sodium carbonate, dried and evaporated, and the residue
distilled, when almost the entire quantity passed over at 128°/
10 mm , and soon crystallised. After draining on porous porcelain
and crystallising from light petroleum mixed with a little benzene,
the substance melted at 44^ and gave the following analytical
results :

0-1780 gave 0-4510 CO2 and 0-1200 HgO. C = 69-1 ; H = 75.
CgH^gOg requires C = 69-5 ; H = 7-2 per cent.

6 H 2

1880 BAUDISCH, HIBBERT, AND PERK IN :

This substance is the lactone of l-77iethi/l-A^-cyc\ohexen-4:-ol-2-carb-
oxylic acid, and identical with the lactone the properties of which
are described in detail on p. 1881. The sodium carbonate extract was
acidified, and extracted at least five times with ether, when a colourless
syrup was obtained which soon solidified. In contact with porous
porcelain, the trace of oily impurity was soon removed, and the
colourless residue was then crystallised from water, in which it is very
readily soluble and from which it separates in glistening crystals :

0-1065 gave 0-2370 COg and 0-088 H2O. C = 607; H = 90.
CgHj^Og requires C = 60-8; H = 8-8 per cent.

0"2150 required for neutralisation 0'0546 NaOH, whereas this

amount of a monobasic acid, Cj^Hj^O,,, should neutralise 0-0544

NaOH.

c\s,{J^)-\-Methylcyc\ohexanA-ol-2-carboxylic acid melts at about

126 — 128° without decomposition, but at 155° decomposition sets in

with elimination of steam and formation of the lactone, and at 160 — 162°

the disengagement of gas is very rapid. In order to prepare the

lactone, the pure acid was distilled under a pressure of 20 mm., when

a quantity of oil passed over at 130 — 135°, and, on again distilling,

almost the whole quantity passed over at 130°/20 mm. :

0-1772 gave 0-4475 COg and 0-1356 HgO. C = 68-8 ; H = 8-5.
CgHjgOa requires 0 = 68-6; H = 8-6 per cent.

This lactone is a rather mobile liquid possessing a faint odour of
coumarin ; it is insoluble in cold dilute sodium carbonate or potassium
hydroxide, but dissolves readily in the latter on warming, with
formation of the salt of the hydroxy-acid.

The oil A (p. 1879), distilling at 185— 195°/15 mm., and obtained in
considerable quantity during the preparation of the mixed lactones,
was refractionated, and, as it distilled remarkably constantly at
184 — 185°/13 mm., it was thought that it was possibly a pure
substance.

The analysis gave the following results :

0-1991 gave 0-4960 OO2 and 0-1419 HgO. 0 = 67-9; H = 8-0,

and, as this agrees approximately with the formula (OgHj20o)2, which
requires 0 = 686; H = 8-6 per cent., it seems probable that the
substance is a double lactone of this formula. When this oil was
dissolved in dilute potassium hydroxide, the solution acidified,
extracted with ether, and the ethereal solution, after thoroughly
drying, evaporated to a small bulk, a crystalline acid gradually
separated in quantity. This was collected and repeatedly recrystallised
from ether, in which it is very sparingly soluble, and from which it
separated in crusts melting at 163 — 165° :

THE REDUCTION OF 4-HYDUOXY-O-TOLUIC ACID. 1881

0-1254 gave 0-2788 CO,, and 0-1017 H.p. C = 60-6; H = 0 0.
Cg H j^Oo requires C = 60-8 ; H = 8-8 per cent.

Examination showed that this acid is trans(A)-l-7»ei/i?/^cyclo/texan-
i-ol-S-carboxylic acid (compare p. 1877), and it appears therefore that
this acid may be distilled under diminislied pressure without under-
going intramolecular change into one of the cis-modifications.

The Lactone of \-Methyl-^^-cyc\ohexenA-ol-2-carhoxijlio Acid,
' 0

This lactone was first obtained from the crude product of the
reduction of 4-hydroxy-o-toluic acid by distillation in a current of
steam as explained on p. 1876. The steam distillate (A) was extracted
with ether, the ethereal solution dried and evaporated, and the
residual viscid syrup left exposed to the air, when it gradu:illy
solidified.

Subsequently, a considerable quantity of the same lactone was
obtained, mixed with the lactone of cis(B)-l-methylcyc/ohexan-4-ol-
2-carboxylic acid, by the process explained on p. 1879.

The crystals were drained on porous porcelain, and crystallised from
a mixture of light petroleum and a little benzene, from which the
lactone separates in magnificent, glistening prisms, often more than
an inch in length :

0-1775 gave 0-4513 COo and 0-1189 H.O. C = 69-3; H = 7-5.

0-1953 „ 0-4961 CO2 „ 01291 H2O. 0 = 692 ; H = 7-5.
OgHjQ02 requires 0 = 69-5 ; H = 7-2 per cent.

The lactone of \-inethyl-^^-cjc\ohexen-\-ol-1-carhoxylic acid melts at
44°, and distils at I287IO mm. and at 178— I8O7IOO mm.

It is readily soluble in benzene, methyl and ethyl alcohols, acetone,
and most of the usual organic solvents, with the exception of light
petroleum, in which it is rather sparingly soluble.

It is insoluble in cold dilute sodium carbonate, but dissolves
gradually on warming, and the solution gives no precipitate on
acidifying, but, when boiled, an oil separates, which is doubtless the
lactone. It dissolves readily in warm dilute sodium hydroxide, and a
quantitative determination of the basicity of the acid produced gave
the following result : 1-1264 of the lactone, dissolved in a little methyl
alcohol, neutralised 0*356 NaOH on boiling, whereas this amount of a
lactone, OgH^^Og, should neutralise 0 352 NaOH on conversion into the
hydroxy-acid. In order, if possible, to obtain the hydroxy-acid, the
lactone was dissolved in excess of dilute potassium hydroxide, acidified,
and extracted with pure ether, when a very viscid syrup was obtained,

1882 THE REDUCTION OF 4-HYDROXY-O-TOLUIG ACID.

which, after remaining a short time over sulphuric acid, yielded
numbers agreeing as closely as could be expected with those required
for the hydroxy-acid :

0-2002 gave 0-4545 COg and 0-135 H^O. C = 61-9 ; H = 7-5.
CgHjjOg requires 0 = 61-5; H = 7-7 per cent.

When this hydroxy-acid is kept over sulphuric acid, or simply left
exposed to the air, it gradually becomes less viscid, and ultimately
comparatively mobile, and, after about a week, the oil is almost com-
pletely insoluble in cold dilute sodium carbonate, a change which
indicates that the hydroxy-acid has been converted into the lactone.
The unsaturated nature of the hydroxy-acid is shown by the fact that
its solution in dilute sodium carbonate instantly decolorises perman-
ganate, but, in spite of several attempts, a crystalline product of this
oxidation could not be isolated.

1 •.i:-Dihromo-\-methylcyc\ohexane-2-carhoxylic ^cic? (Formula, p. 1875).

When the lactone of 1 -methyl- A"-c?/c?ohexen-4-o]-2-carboxylic acid
(5 grams) is just melted and mixed with fuming hydrobromic acid
(saturated at 0°, 15 c.c.') it dissolves, and, if the solution is left in the
ice-chest, crystals gradually begin to separate.

After six days a considerable crust had formed, which was collected,
left in contact with porous porcelain over solid potassium hydroxide
until quite dry, and the nearly colourless residue crystallised from a
mixture of benzene and light petroleum, from which it separated in
colourless crusts :

0-2715 gave 0-3335 AgBr. Br = 52-3.

0-2173 „ 0-2691 AgBr. Br = 53-0 per cent.

This dibromo-acid softens at 148° and melts at about 158 — 160° with
evolution of gas. It is readily soluble in methyl alcohol, ether,
benzene, or chloroform, but sparingly so in cold light petroleum.
The finely-powdered dibromo-acid dissolves in cold dilute sodium
carbonate, but decomposition immediately sets in, with the gradual
separation of a heavy oil which has the odour of a bromo-hydrocarbon,
and this decomposition is much hastened by warming. Heating with
pyridine or diethylaniline appears to produce a similar change.

The authors wish to state that much of the heavy expense of this
investigation was defrayed by a grant from the Government Grant
Fund of the Royal Society.

Thb Univek.sity,

Manchestek.

THE REDUCTION OF 0-HVDROXV-()-T()LUlC ACID. 1883

CCVlir. — The RednctioR of i)-[fi/<lro.vi/-o-toluic Acid.

By Oscar Baudisch and William Henry Pehkin, jun.

OsCAii Jacobsen describes two methods for tlio preparation of 6-hydr-
oxy-o-toluic acid (" yy-oithohomoraetaox) benzoic acid"), namely, from
()-!~vdpho-o-toIiiic acid by fusion with potassium hydroxide (Ber., 18tt3,
16, 19<)3) and from G-amino-o-toluic acid (" ^-amino-o-toluic acid ") by
treatment witli nitrous acid {Ber., 1884, 17, lfi3), and states that it
crystalh'ses from water in long, glistening needles of melting point
183°. We have carefully repeated these experiments, and find that the
acid of melting point 183° is nut 6-hydroxy-o-toluic acid (I) as Jacobsen
supposed, but 4-hydroxy-o-toluic acid (II),

HO ^le Me

/ NcO.H <^ ^COgH

0H~

(I.) (II.)

that is to say, it is identical with the acid of this constitution described
in the preceding paper (p. 1875).

There can, therefore, be little doubt that the sulpho-o-toluic acid and
the amino-o-toluic acid employed by Jacobsen in the preparation of
this acid of melting point 183° are in both cases the 4- and not the
G-derivatives of o-toluic acid.

6-Hydroxy-o-toluic acid appears to have been first prepared by
Kalle & Co. (D.R.-P. 91201; Friedlander, Forlschritte der Teerfarben-
fahrikation, IV, 148) from naphthalene-1 : 3 : 5-trisulphonic acid, 2-
naphthylamine-4 : 8-disulphonic acid, l-naphthylamine-3 : 5-disulphonic
acid, or 5-amino-l-naphthol-3-sulphonic acid by heating with sodium
hydroxide at 250°.

All the.se derivatives of naphthalene contain the substituting groups
in the positions marked by asterisks in the formula

and the decomposition of the molecule by the fused alkali leads to the
disruption of the right-hand ring in all cases. Thus, in the case of
naphthalene-1 : 3 : 5-trisulphonic acid, the change may be represented
in the following manner :

. I |^^2^

^ I JCH3

OH

1884 BAUDISCH AND PERKIN :

Kalle «fe Co. state that 6-liydroxy-o-toluic acid melts at
141*5 — 142°, but according to Einliorn and Pfyl (Annaleii, 1900,
311, 52) this acid melts at 145 — 146°. The large quantities of
6-hydrox3'-o-toluic acid which were employed in the present investiga-
tion were prepared by heating the sodium salt of 2-naphthylamine-
4 : 8-disulphonic acid,

with sodium hydroxide, and we can confirm the statement of Kalle
ct Co. that the pure acid melts at 141 -5 — 142°.

When 6-hydroxy-o-toluic acid is reduced by sodium and alcohol, it
yields a mixture of hydroxyhexahydro-acids, from which we have
isolated one trans- and one cts-modification, and, although there was
evidence of the presence of a third acid (compare p. 1886), we were
unsuccessful in our attempts to obtain it in a pure condition.

tra,ns-l-AIethylGyc\ohexan-2-ol-6-carboxylic acid (I) melts at 170 — 172°,
and, when rapidly heated under diminished pressure, distils for the
most part unchanged at about 180°/ 15 mm. It is converted by
treatment with hydrobromic acid into the corresponding syrupy
bromoncid.

cis-l-Methylcjc\ohexan-2-ol-Q-carboxyliG acid (II) melts at 150°,

CHMe ^™'

/ \ / \

OH-C-H H-C-CO„H H-C'OH H-C-CO„H

I I 2 I I 2

\ / \ /

CH \/

(I.) (II.)

and, when heated, is converted into the syrupy lactone, which
distils at 128 — 130°/ 15 mm., and both the acid and the lactone
react with hydrobromic acid with formation of the syrupy c'ls-bromo-
acid.

The investigation of the unsaturated esters produced by the action
of diethylaniline on the esters of the trans- and cis-bromo-1-methyl-
cyc^ohexane-2-carboxylic acids will form the subject of a future
communication.

THE REDUCTION OF 6-HYDROX Y-O-TOLUIC ACID. 1885

The Reduction of ^-Ilydroxy-o-toluic Acid.

The 6-hydroxy-o-toluic acid required for these experiments was
obtained by heating sodium 2-naphthylamine-4 : 8-disulphonate *
(1 kilo.) with sodium hydroxide (4 kilo.«. of 50 per cent.) in an
autoclave for ten hours at 250 — 260°, when decomposition took place
slowly with the development of great pressure, due principally to the
formation of large quantities of ammonia. The product was mixed
with a little water, nearly neutralised with hydrochloric acid, filtered,
and then acidified with excess of hydrochloric acid. After remaining
overnight, the precipitate was collected, washed with water, and
crystallised from water with the aid of animal charcoal.

The acid obtained in this way melts at 141 '5 — 142°, and is pure
6-hydroxy-o-toluic acid, but the yield obtained is unfortunately not
more than 10 per cent, of that theoretically poi^sible, so that the
preparation of the large quantities of this acid which were required
for this investigation was very laborious, and, indeed, necessitated the
fusion of 14 kilos, of the sodium salt of 2-naphthylaminedisul phonic
acid with sodium hydroxide. A small quantity of the pure hydroxy-
acid was converted, by treatment with alcohol and sulphuric acid in
the usual manner, into ethyl 6-hydroxy-o-toluate, which melted at 69°,
as stated by Kalle &, Co. (loc. cit.), and yielded on analysis :

0-1614 gave 0-3935 CO.^ and 0-0980 H^O. C = 66-5; H = 6-7.
CjqH^.,03 requires 0 = 667; H = 6-7 per cent.

The reduction of 6-hydroxy-o-toluic acid by means of sodium and
alcohol was carried out under the conditions described in detail in the
case of the reduction of 4-hydroxy-o-toluic acid (p. 1876) and in the
same apparatus. The product of the reduction, after the removal of
the alcohol, was acidified with excess of hydrochloric acid, extracted
four times with ether, the ethereal solution carefully dried, evapoi-ated,
the residual syrupy mixture of hydroxy-acidsf esterified, and the esters
fractionated under diminished pressure, when a large quantity of a
pale yellow, viscid oil passed over at 140 — 180°/15 mm., leaving a
considerable amount of a brown resin in the distilling flask. On
refractionating, a small quantity of an unsaturated ester passed over
below 130°/15 mm., and then the mixed hydroxy-esters distilled at about
145 — 147°/15 mm. This ester (60 grams) was mixed with potassium

* We are greatly indebted to Messrs. Cassella k Co. for a large suj)ply of tliis
valuable salt.

t It is stated on p. 1876 that the crude product of the reduction of 4-hydroxy-
o-tohiic acid yields an unsaturated lactone in considerable quantity when it is
distilled in a current of steam, but only traces of an unsaturated lactone were
obtained when the crude product of the reduction of the 6-hydroxy-acid was
similarly treated.

1886 BAUDISCH AND PERKIX :

hydroxide (30 grams) in methyl alcohol, and, after remaining over-
night, the product was heated for one hour on the water-bath, water
was then added, the alkaline solution saturated with carbon dioxide,
evaporated until free from methyl alcohol, acidified, and extracted
eight times with ether. After drying over anhydrous sodium
sulphate, the ethereal solution was evaporated, and the amber syrup
left for several days exposed to the air and until crystallisation
appeared to be complete, a process which was much hastened by
stirring from time to time. The mass was left in contact with
porous porcelain until free from oily impurity, and the colourless
residue systematically crystallised from dry ether and then from
water, when it gradually separated into irans-l-methylc?/c^hexan-2-
ol-6-carboxylic acid, melting at 170 — 172°, and the corresponding cis-
acid, melting at 150 — 151°, the former being the less soluble, but
there was also present a considerable quantity of a more soluble
acid, which melted at about 128 — 133°, and gave the following
results on analysis :

0-1704 gave 0-3795 COo and 01396 H,0. 0 = 607 ; H = 9-2.
CgH^^Og requires C = 60'8 ; H = 8"8 per cent.

This acid appears to be a second c^s-modification, but we were
unable, in spite of many crystallisations from different solvents, to
obtain it quite free from the other modifications.

1 -Methylcyc\ohexan-1-one-^-carhoxylic Acid,

A quantity of the acid just described, melting at 128 — 133° (15
grams), dissolved in water (200 c.c.) was gradually oxidised on the
water-bath with potassium dichromate (11 grams) dissolved in water
(100 c.c.) and sulphuric acid (15 grams). The product was saturated
with ammonium sulphate, extracted, the viscid syrup mixed with
excess of semicarbazide hydrochloride and sodium acetate, and the
semicarbazone, which gradually separated, collected, washed well,
decomposed with dilute hydrochloric acid, and the keto-acid extracted
with ether.

The syrup, obtained on distilling off the ether, crystallised, and,
after washing with small quantities of dry ether on porous
porcelain, the colourless residue gave numbers agreeing approxi-
mately with those required for l-7nethylcyc\oIiexan-2-one Qcarboxylic
acid :

0-1425 gave 0-3172 CO.3 and 0-1081 H^O. C = 607; H = 8'4.
CgHj.^Og requires 0 = 61-5; H = 7-7 per cent.

This acid melted at about 97°, but, since it was not found possible

THE REDUCTION OF 6-HYDROXY-O-TOLUIC ACID. 1887

fco recrystallise it satisfactorily, this melting point can only be approxi-
mate. The keto-acid is very soluble in water, and its behaviour seemed
to indicate that it was a mixture of cis- and <ra?Z8-isomerides. The
solution of the acid gives no immediate precipitate with semicarb-
azide hydrochloride and sodium acetate, but the semicarbazone
soon begins to separate in flakes, and melts at about 200 — 205° with
decomposition :

0-1320 gave 22 c.c. ^^ at 18° and 762 mm. N = 19-5.
C,)Hj503N3 requires N= 19'7 per cent.

tva.ns-l-Methi/lcyc\ohexan-2 ol-Q-carboxi/lic Acid.

This acid melts at about 170 — 172° is sparingly .'<oluble in cold
ether, and sepai'ates, when the solution is concentrated and rapidly
cooled, in colourless, crystalline crusts. If, however, the solution is
allowed to cool very slowly or to evaporate spontaneously, the acid
separates in well defined, glistening prisms, like sugar crystals. It is
readily soluble in water, and separates from this solvent in characteristic
woolly balls. Two different specimens crystallised from ether and
water respectively gave the following results on analysis :

0-1420 gave 0-3160 C0._, and 0-1160 HgO. C = 60-7; H = 9-0.

0-1706 „ 0-3788 CO2 „ 0-1397 Hp. C = 60-5 ; 11 = 91.
CgH^^Og requires C = 60-8 ; H = 8'8 per cent.

On titration with iVyiO-sodium hydroxide, O'SOll neutralised 00761
NaOH, whereas this amount of a monobasic acid, CgHj^O^, should
neutralise 0-0762 NaOH. The <raws-hydroxy-aoid dissolves readily in
hydrobromic acid (saturated at 0°), and there is no apparent change at
the ordinary temperature even after several days, but, when heated on
the water-bath, the solution clouds, and a syrup separates which
analysis showed to consist of almost pure tvAiis Q-bromo-l-methylcyc\o-
hexane-2-carboxi/Hc acid. Several attempts were made to obtain the
corresponding keto-acid by oxidising the fran«-hydroxy-acid with
dichromate, but without success. When the theoretical amount of oxi-
dising agent was employed, a good deal of unchanged hydroxy-acid
was always recovered, and excess of oxidising agent apparently
caused profound decomposition, since only a trace of a keto-acid could
be isolated, and that in an impure state.

cis-\ -Methylcyc\ohexan-2-ol-Q-carboxylic Acid and its Lactone.

The porous plates which had been used in the purification of the
cis- and tra7is-a.cids (p. 1886) were broken up, extracted with ether in a
Soxhlet apparatus, the extract mixed with the residue obtained when
the various mother liquors from the purification of the cis- and trans-

1888 THE REDUCTION OF 6-HYDROXY-O-TOLUIC ACID.

acids was evaporated, and the whole (80 grams) distilled under 15 mm.
pressure. A considerable quantity passed over below 155° and most of the
remainder distilled at 180 — 195°, and when the oil of lower boiling
point was redistilled, a considerable quantity of a rather mobile oil
was obtained, which distilled constantly at 128— 130°/15 mm. :

0-1670 gave 0-4180 COo and 0-1330 H.3O. C = 68-2; H = 8-8.
01665 „ 0-4192 CO2 „ 0-1310 H^O. 0 = 686 ; H = 8-7.
CjjHjgOa requires C = 68-6 ; H = 8-6.

This substance is the lactone of cis-l-methylcjc\ohexan-2-ol-Q-carb-
oxylic acid, and is a colourless oil possessing the peculiar odour
characteristic of cyclic lactones. It is insoluble in sodium carbonate
and cold dilute potassium hydroxide, but dissolves readily in the latter
on warming, with foriiation of tlie salt of the cis-hydroxy-acid. In
order to obtain the fi-ee acid, the well cooled alkaline solution was
acidified, extracted sevei^al times with ether, the ethereal solution
dried, and evaporated at a low temperature, when a colourless syrup
was obtained which rapidly crystallised.

After remaining in contact with porous porcelain until quite dry,
the colourless residue sepai-ated from ether in glistening crusts,
melted at 149 — 150°, and was identical with the cis-acid obtained
directly from the product of the reduction of 6-hydroxy-o-toluic
acid (p. 1886), Of the following analyses, the first was made with
material obtained directly from the reduction, and the second with a
specimen of the acid which had been prepared from the lactone :

01 565 gave 0-3476 OOg and 0-1289 H,0. 0 = 606 ; H = 9-2.
0-2088 „ 0-4645 CO2 „ 0-1720 HgO. 0 = 60-7 ; H = 9-l.
OgHj^Og requires 0 = 60-8 ; H = 8-8 per cent.

03117 neutralised 0-0784 NaOH, whereas the theory for this
quantity of a monobasic acid, OgH^^Og, is 0-0788 NaOH.

cis-l-Melhylcjc]ohexan-2-ol-6-carboxylic acid melts at 150 — 151°, and
decomposes slowly at 165°, but much more rapidly at 180° into steam
and the lactone. It is readily soluble in water, but sparingly so
in cold dry ether. The powdered acid dissolves readily in fuming
hydrobromic acid (saturated at 0°), but, even after sevei'al days,
no separation of the Ijromo-acid takes place at the ordinary tempera-
ture. When, however, the solution is heated on the water-bath, the
cis-bromo-acid separates as a viscid layer on the surface of the hydro-
bromic acid. The lactone of the cis-hydroxy-acid dissolves at once in
fuming hydrobromic acid with slight evolution of heat, and, when left
overnight, the liquid clouds and a viscid syrup separates, a change
which takes place rapidly on warming.

The product was diluted with water, extracted with ether, the

THE REDUCTION OF 5-H VDUOXY-M-TOLUIC ACID. 1X80

ethereal solution well washed, ilried, evaporated, and the residue
left for a short time over sulphuric acid in an evacuated desiccator.

Analysis then yielded the following numbers, wliich agree well
with those required for cis G bfomol-inelhylcyc\o/iexane-2-carboxylic
acid :

0-1798 gave 0-1528 AgBr. Br = 36a.

CgHjgOgBr requires Br = 36'2 per cent.

The viscid oil, described at the beginning of tliis section, which
distilled at 180 — 195°/15 mm., was again fractionated, when it
distilled remarkably constantly at 185°/15 mm., and gave, on analysis,
C = 63'G and H = 8'5 per cent. When this syrup was stirred well
with dry ether (2 vols.) and left for several days, a crust separated,
which, after crystallising from ether, melted at 169 — 170°, and gave
on analysis the following result :

01173 gave 0-2065 CO2 and 0-0971 HgO. C = 60-7; H = 9-2.
CgH^^Og requires C = 60-8 ; H = 8*9 per cent.

That this acid was <rrt?is-l-methyk2/c^ohexan-2-ol-6-carboxylic acid
was proved by mixing it with a specimen of this acid which had been
obtained by the method described on p. 1886, when the mixtux^e melted
at 168 — 170°. The above experiment clearly demonstrates that the
acid of melting point 169 — 170° distils without the formation of a
lactone, and confirms the view adopted in this communication that
it is <ra«.s-l-methylcyc^c»hexan-2-ol-6-carboxylic acid.

The University,

Manchester.

CCIX. — The Reduction of b-Hydroxy-va-toluic Acid.

By Andrew Norman Meldrum (Carnegie Research Fellow) and
William Henry Perkin, jun.

The present investigation was undertaken with the object of preparing
unsaturated acids of the constitution

CH<g^^^g^>CH.CO,H and 0^,<l^^;S^^Qn'QO,ll,

in order, with their aid, to attempt the synthesis of the two terpenes :

CH<^™^'^^2>CH»CMe:CH, and

CH2<^™!1^^^2>cH-CMe:CH„.

1.S90 MELDRUM AND PERKTN :

These terpenes are of considerable interest, not only because they are
unknown members of the meta-series, but also because it is possible
that one of them may be the inactive modification of sylvestrene, the
constitution of which is still doubtful.

In order to synthesize the unsaturated acids figured above, it was
necessary to prepare large quantities of 5-hydroxy-»i-toluic acid,

HO

and this proved to be a task of considerable difficulty. This acid
appears to have been first prepared by Jacobsen (Ber., 1881, 14,
2357) from 7?i-toluic acid by sulphonation and subsequent fusion with
potassium hydroxide. Jacobsen showed that m-toluic acid is converted
by treatment with fuming sulphuric acid at 160° into a mixture of
sulphonic acids which, on fusion, yields, besides small quantities of
tsophthalic acid and a-hydroxyisophthalic acid, the following hydroxy-
??i-toluic acids :

Me Me

~UH ho"

4-Hydroxy-?>i-toluic Acid. M. p. 149°. 5-Hydroxy-7n-toluic Acid. M. p. 208°,

and these, he states, are produced in approximately equal quantities.

At a later date, Claisen and Stylos (Ber., 1887, 20, 2188 ; compare
Claisen, Ber., 1889, 22, 3271, and Tingle, " Ueber die Einwirking von
Oxalather auf aliphatische Ketone," Inaug. Diss., Munich, 1889)
showed that 5-hydroxy-??i-toluic acid may be synthesised from ethyl
acetoneoxalate by the following interesting series of reactions. The
sodium derivative of ethyl acetoneoxalate is decomposed by water and
dilute acids with formation of an acid, CjqH^gOg (m. p. 91°), a
decomposition which Claisen formulates thus :

CH^Ac-CO-CO^Et ^„n - CH2Ac-C(OH)-C02H
CH^Ac-CO-CO^Et +^2^ - CHAc-C0-C02Et +^^^^-

When this acid is digested with barium hydroxide, it is decomposed
with elimination of oxalic acid and formation of 5-hydroxytoluic acid,
diacetoneoxalic acid being evidently an intermediate stage :
CH,Ac-C(OH).CO,H CH.Ac. ^,^„. ^^ „ _^

CHAc-CO-CO^Et -^ CH,Ac>^(^H) C^^H -^

It seemed at first likely that this elegant synthesis might prove to
be the most convenient method for obtaining the 5-hydroxy-7?z-toluic
acid required for this research, but careful investigation, under a

THE REDUCTION OF 5-HYDROXY-M-TOLUIC ACID. 1891

variety of conditions, showed that, whilst it is an excellent method
for the rapid preparation of small quantities, it is unsuitable,
principally owing to the large volumes of liquid involved,
for the preparation of large quantities. We therefore returned to
Jacobsen's method and investigated, in considerable detail, the
sulphonation of 7n-toluic acid. We found that 7n-toluic acid is readily
sulphonated at 160° by pure sulphuric acid and, under these conditions,
the principal product is 5-sulpho-m-toluic acid,

]\Ie_

SOsH

but considerable quantities of the 4- and 6-sulphonic acids,
Me Me

/ \cO2H SOgH/^ NcOaH,

"SOgH ~

are always produced at the same time. When these sulphonic acids
are fused with potassium hydroxide, they yield the three hydroxy-m-
toluic acids,

Me Me Me

/ NCO2H ^ y^O^'B. 0H<^ ^C02H,

5-Hydroxy-7?i-toluic 4-Hydroxy-m-toluic 6-Hydroxy-?rt-toluic

Acid. M. p. 208° Acid. M. p. 150°. Acid. M. p. 172°.

and as the yield of the 5-hydroxy-acid is satisfactory, this method was
adopted for the preparation of almost the whole of the acid required for
the present investigation. 5-Hydroxy-?n-toluic acid is not so readily
reduced by sodium and alcohol as 7n-hydroxybenzoic acid (Trans., 1907,
91, 486), but reduction takes place quickly and almost completely in
boiling isoamyl-alcoholic solution.

It israther remarkable, in view of our experience in othersimilarcases
(compare Tran?., 1908, 93, 1417, and the two preceding communica-
tions), that, although four stereoisomeric l-methylc?/cZohexan-3-ol-5-
carboxylic acids might result from this reduction, we have only been
able to isolate one acid of melting point 138 — 139°, and, if any of the
other possible acids are produced at all, it must be in very small
quantities. The careful investigation of its properties has shown that
the acid of melting point 138 — 139° is tra.ns-l-inethylcyclokexan-3-ol-5-
carhoxylic acid (1).

When the crude <ra?is-acid is distilled, it is converted partly into the
lactone of the cis-acid (b. p. 130 — 132°/ 13 mm.), and this, on hydrolysis,

1892 MELDRUM AND PERKIN :

yields pure c\&-\-methylcyc\o]iexanZ-ol-b-carhoxylic acid (II), which,

like the frans-modification, melts at 138 — 139°, but the careful

investigation of their properties clearly proves that the two acids are

CHIMe CHMe

/ \ / \

CH2 CH., CJHg CJHo

OH-C-H H-C-CO^H H-C-OH H-C-COoH

\ / \ /

\y \ /

CH2 CHg

(I.) (II.)-

distinct. Both the cis- and ira?is-hydroxy-acids are converted by
fuming hydrobromic acid into the corresponding bromo-^c'id.^, and these,
on treatment with diethylaniline, yield unsaturated acids, the investiga-
tion of which is in progress.

When ethyl /rans-l-methylc^c^ohexan-3-ol-5-carboxyIate is oxidised
with chromic acid, it is converted into ethyl-l-methylcyclohexan-3-one-5-
carhoxylale, which distills at 138 — 140°/ 15 mm., and, on hydrolysis,
yields the corresponding acid,

This syrupy keto-acid distils at 192°/15 mm., and yields a crystalline
oxime (m. p. 142°), but does not appear to combine readily with semi-
carbazide.

It has already been stated that one of the acids resulting from the
sulphonation of m-toluic acid is 6-sulpho-?n-toluic acid, and that this,
on fusion with potassium hydroxide, yields 6-hydroxy-m-toluic acid.

Me

oh/ \cOoH.

This acid is of special interest in connexion with the experiments on
the synthesis of the terpenes, becau.se if it could be reduced by sodium
and alcohol, it would yield l-methylcyc/ohexan-2-ol-5-carboxylic acid,
fiom which, by elimination of water and subsequent treatment with
magnesium methyl iodide, isocarvestrene should result :

OH-CH<^g^^^^3>c;H-C02H -^ CH<^^^^^][j2>cH-C02H

isoCarvestrene.
The actual process employed in the .synthesis of wocarvestrene and
its derivatives (Fisher and Perkin, Trans., 1908, 93, 1877) is a com-
plicated and very laborious one, and, as the method indicated above
would be much more direct and considerable quantities of 6-hydroxy-

THE REDUCTION OF 5-HYDIlOXY-M-TOLUIC ACID. 1893

?n-toluic acid had accumulated, a series of experiments was made with
the object of reducing it to the corresponding hexahydrovdei ivative.

The acid was treated with ethyl aU-ohol and sodium and witli iso-
amyl alcohol and sodium under a variety of conditions, but in no case
could any indication of reduction be observed, a result in harmony
with a series of unsuccessful experiments which had previously been
made in the hope of reducing ;>hydroxy ben zoic acid under similar
circumstances.

Sulphonatioii of m-Toluic Acid.

After a series of comparative experiments, the following process
was adopted for the sulphonation of the large quantities of ?/i-toluic
acid which were required for this investigation. The puie acid
(250 grams) and pure sulphuric acid (750 c.c.) are heated in a bolt-
head at 180° for eight hours, the temperature being carefully
regulated by a gas regulator, and the whole being stirred or agitated
from time to time in order to ensure perfect mixture. The product
is allowed to cool, mixed with water (900 c.c), and left overnight,
when a mass of small crystals gradually forms, and when the
separation is complete, the whole is filt<^red through flannel by the aid
of the pump and drained on porous porcelain. The filtrate (A) was
kept for further examination (p. 1894). The crude 5-sulpho-m-toluic
acid thus obtained is crystallised either from water or by adding
hydrochloric acid to the concentrated aqueous solution,* and a specimen
which had been repeatedly recrystallised melted at 110° and gave the
following results on analysis :

0"2506 neutralised 00794 NaOH, whereas this amount of a dibasic
acid, CgHs0^8,2H20, should neutralise 00795 NaOH, and this
result was confirmed by the titration of several different
specimens.

5-Sulpho-m-toluic acid yields two very chai'acteristic salts.

The Sodium Hydrogen Salt, C3H^05SNa,2H.,0. — This beautifully
crystalline salt separates when hydrochloric acid is added to the
concentrated solution of the neutral sodium salt, and is readily
purified by crystallisation from water, from which it separates in
glistening plates :

0-2401 gave 0-0614 Na.^SO^. Na = 8-29.

0-2813, heated at 140° until constant, lost 0 0.372. H20= 1.3-22.
C8H-05SNa,2H20 requires Na = 8-4 j H20= 13 14 p"er cent.

The titration of this salt with A710-sodium hydroxide gave the
following results :

* The mother liquors (B) from these crystallisations were carefully investigated
(p. 1895).

VOL. XCV. 6 I

ISfU MELDRUM AND PERKIN :

04386 neutralised 0*064 NaOH, whereas this amount of tlie sodium
hydrogen salt should neutralise 0'064 NaOH.

llie Barium Hydrogen Salt, (C^H70,.^S)2Ba,7H20. — This salt was
prepared by taking a measured quantity of the aqueous solution of the
pure sulphonic acid, neutralising one half with b'lrium carbonate,
filtering, and adding the other half. It is readily soluble in hot water,
and separates, when the hot concentrated solution is cooled, in slender,
flexible needles :

0-1124 gave 0-0384 BaSO^. Ba = 20'lL

CjgH^^OjoS^BajTHgO requires Ba= 19-82 per cent.

The composition of this salt was controlled by titration with Nj\0-
sodium hydroxide, when 0-1678 neutralised 00194 NaOH, whereas
this amount of a salt of the above composition should neutralise
0-0193 NaOH.

The yield of S-sulpho-m-toluic acid varies considerably in different
experiments, but we have several times obtained as much as 400 grams
of the pare acid from 500 grams of 7/i-toluic acid.

The conversion of 5-sulpho-??i-toluic acid into 5 hydroxy-?n-toluic
acid by fusion with potassium hydroxide is described on p. 1895.

The original mother liquors (A, p. 1893), from which the crystals
of crude 5-sulpho-m-toluic acid had separated, were diluted with
water and neutralised with chalk. The filtrate and washings from
the calcium sulphate were converted into potassium salt by the
addition of potassium carbonate, and, after filtering, several crops of
potassium salt were obtained by repeatedly concentrating the aqueous
solution. The first crop of potassium salt yielded, on fusion with
potassium hydroxide, an acid which, after repeated crystallisation from
water, separated in long needles of melting point 149 — 150°, and gave,
with ferric chloride, a bluish-violet coloration.

This acid was easily recognised as 4-hydroxy-m-toiuic acid
(a-cresotinic acid),

<^_\C02H,
~0H

and its formation shows that one of the pi^oducts of the sulphonation
of 9n-toluic acid is 4-sulpho-m-toluic acid.

The second and third crops of potassium salt yielded, on fusion
with potassium hydroxide, some 4-hydroxy-m-toluic acid, but prin-
cipally an acid which, after repeated fractional crystallisation, separated
from water in slender needles melted at 172 — 173°, gave no colora-

THE REDUCTION OF O-HYDHOXV-M-TOLUIC ACID. 1.S95

tion with ferric chloride, and proved to be 6-hydroxy-?>t-toluic
acid,

Evidently, then, one of the products of the sulphonation of ?/i-tolaic
acid is 6-sulpho-?>i-toluic acid.

The motlier-liquors (B, p. 1893) from the crystallisation of the crude
sulphonic acid, and which had accumulated in considerable quantity,
were freed from sulphuric acid by treatment with the exact quantity
of barium hydroxide in the usual manner. The filtrate from the
barium sulphate was divided into halves, one of which was neutralised
with barium carbonate, the other was then added and the liquid con-
centrated. The first crop which separated consisted of the hydrogen
barium salt of 5-su]pho-«t-toluic acid, since, after conver.-ion into the
potassium salt and fusion with potassium hydroxide, it yielded
5-hydroxy-7?i-toluic acid m. p. 208°).

The more soluble salt consisted essentially of the hydrogen barium
salt of 6-sulpho-OT-toluic acid, and yielded, after conversion into the
potassium salt and fusion with potassium hydroxide, 6-hydroxy-m-
toluic acid (m. p. 173°). During this series of experiments, although
careful search was made, there was no indication of the presence of
2-sulpho-?«-toluic acid,

COoH,

and it seems probable that this isomeride is not formed during the
sulphonation of ?«-toluic acid.

6'Hydroxy-im.-toluic Acid

This acid was prepared in large quantities (about 1500 grams) for
the purposes of this research, and every effort was made to obtain it in
as pure a condition as possible. The sulphonic acid employed was
twice recrystallised from water, and then added, in quantities of 50
grams, to potassium hydroxide (150 grams), and the whole gradually
heated (during about half an hour), with constant stirring, until the
tempeiature reached 260°.

The product was dissolved in water, nearly neutralised with hydro-
chloric acid, mixed with a little animal charcoal, concentrated, and,
after remaining overnight, the filtrate from the animal charcoal and
potassium chloride was acidified and the crystalline acid collected and
well washed. In oider to purify the acid further, it was converted

6 I 2

1896 MELDRUM AND PERKIN :

into the characteristic calcium salt, (CgH703)2Ca,2HoO, described by
Jacobsen {Ber., 1881, 14, 2358), and for this purpose the acid was
ground to a paste with water, digested with precipitated calcium
carbonate, and the filtrate concentrated, when the salt separated in
magnificent, glistening prisms. This salt was recrystallised until quite
pure, and a specimen yielded, on analysis, numbers confirming the com-
position assigned to it by Jacobsen.

0-3058, heated at 100^ until constant, lost 0-0296 H^O, and gave on
ignition 0-0448 CaO. H20 = 9-68; Ca = 10-47/
Ci,H^p^Ca,2H20 requires H,0 = 9-52 ; Ca = 10-58 per cent.
Finally, the pure salt was dissolved in boiling water, acidified with
hydrochloric acid, the acid collected, and crystallised once from water ;
it then melted at 208°, and consisted of pure 5-hydroxy-?H-toluic acid.
The yield obtained from m-toluic acid varied considerably in different
preparations, but was usually about 40 per cent.

During the earlier stages of this research, we attempted to prepare
the 5-hydroxy-?H-toluic acid required from ethyl oxalate and acetone by
the method described by Claisen and Miller {Ber., 1899, 22, 3271),
but, at first, without success. Subsequently, Dr. J. B. Tingle was kind
enough to send us a copy of his dissertation which deals with this
series of reactions, but does not appear to have been published,
and, by modifying the process in some of its details, we ultimately
prepared considerable quantities of 5-hydroxy-m-toluic acid in this way,
but the method was found to be more laborious than that based on the
sulphonation of »i-toluic acid.

Sodium (23 grams) was dissolved in absolute alcohol (350 c.c), and
the solution added to a mixture of acetone (58 grams) and ethyl oxalate
(146 grams), when, after some time, the whole became semi-solid, owing
to the separation of the sodium derivative of ethyl acetoneoxalate,
CHAcNa*C0'C02Et. This was collected, transferred to a bottle, and
shaken mechanically with glacial acetic acid (300 c.c.) for two hours.
The crystalline precipitate which had separated, and contained about
6-7 per cent, of sodium, was collected, washed with ether, ground up
with water and excess of dilute sulphuric acid, and the colourless,
crystalline precipitate melting at 89°, and consisting of the substance
CH2Ac-C(OH)-C02H

CHAc-CO-COpEt
(see p. 1890), collected and digested in quantities of 100 grams with a
solution of barium hydroxide (155 grams) in water (1 litre) on the
water-batli. After about thirty minutes, the barium oxalate was
removed by filtration, the filtrate neutralised, concentrated, and
acidified, when crude 5-hydroxy-OT-toluic acid (28 grams) separated, and,
after one crystallisation from water, melted at 208°, anfl was quite pure.

THE REDUCTION OK 5-HYDROXY-M-TOLUlC ACID. 1897

Tlie Reduction of ^-Ilydroxy-iw-toluic Acid.

Since preliminary experiments showed that this acid is not I'eadily
reduced by sodium and alcohol, we decided, in the first phvce, to
investigate its behaviour on reduction with sodium and i«oamyl alcohol.
The pure acid (35 grams) was di.ssolved in ?.soamyl alcohol (1300 c.c),
the solution heated to boiling, and then sodium (130 grams) added as
rapidly as possible. When all the sodium had dissolved, the mass was
mixed with water, the isoamyl alcohol layer separated, washed several
times with water, and the combined aqueous layers neutralised and
evaporated to a small bulk.

The sotiium chloride which crystallised out was removed, and the
filtrate acidified, when a syrup separated which soon began to crystal-
lise. After remaining for several days in the ice-chest, the ci-ystalline
mass was collected, and left in contact with porous porcelain until
quite free from oil, when the almost colourless residue weighed 17
grams. This was ground with a little ether, washed with ether, and
repeatedly crystallised from water :

0-1347 gave 0 2996 CO2 and 0-1058 HjO. 0 = 607; H = 8-7,
CgHj^Og requires C = 60-8 ; H = 88 per cent.

0-3420, dissolved in water and titrated with i\710-sodium hydroxide,
required 0-0862 NaOH for neutralisation, whereas the theoretical
amount is 00.S65 NaOH.

tvsins-\-Methyk'yc\ohexan-'6-ol-^-ca7'hoxylic acid melts at 138 — ^139°,
and, unlike the ci»-acid, shows no signs of decomposing at 150°;
when, however, it is heated at 180°, slow decomposition sets in, and
becomes rapid at 200°. It is readily soluble in hot water, and
separates on cooling in crystalline crusts.

In ether it is very spaiingly t-oluble, and when the warm saturated
solution is concentrated, the acid separates after some time in
crystalline crusts, which are bright while under the ether, but, when
exposed to the air, rapidly become chalky. The salts of the acid do not
crystallise well. The ammonium, potassium, and sodium salts are very
soluble in water, and the solutions of the calcium and barium salts,
when concentrated, set to jellies.

The transsicidi dissolves readily in fuming hydrobromic acid
(saturated at 0°), and separation of crystals does not occur when the
solution is left for forty- eight hours (compare the behaviour of the
CIS-acid under the same conditious). If the solution is allowed to
evaporate over potassium hydroxide and sulphuric acid in a vacuum
desiccator, a gummy acid containing bromine remains. The clear
solution of the fraws-acid in hydrobromic acid gradually clouded on
the water-bath and, in a fe^v minutes, an oily layer separated on the

1898 MELDRUM AND PERKIN :

surface, and when separation was complete, the whole was diluted with
water, extracted with ether, the ethereal solution washed, dried,
evaporated and left exposed over sulphuric acid in a vacuum
desiccator for several hours. The nearly colourless syrup yielded the
the following results on analysis :

0-2857 gave 0-2346 AgBr. Br=35-1.

CgHjgO.jBr requires Br = 36-2 per cent.

This substance is evidently nearly pure trnQS-5 -bi-omo-l-iiiethyl
cyc\ohexane-3 -carboxylic acid.

cis-l -Methylcjc\ohexan-3-ol-5-carboxylic Acid.

The porous plates used in the purification of the trans-acid were
extracted with ether in a Soxhlet apparatus, and the crude syrup re-
maining after the removal of the ether slowly distilled under 12 mm.
pressure. At 6rst much water was given off, and then an oil distilled
at 120 — 160°, followed by a considerable quantity of a pale yellow oil
distilling at 210 — 220°. The oil of lower boiling point yielded, on
repeated fractionation, a lactone distilling at 130 — 132°/ 13 mm. :

0-2081 gave 0-5226 COg and 0-1655 H.fi. C = 68-5 ; H = 8-8.
CgHj.202 requires C = 68-6 ; 11 = 8-6 per cent.

This lactone of cis-l-methylcjc\ohexan-o-ol-5-carboxi/lic acid has the
odour characteristic of lactones of this nature ; it is insoluble in
sodium carbonate and dilute potassium hydroxide in the cold, but
dissolves readily in the latter on warming. In order to prepare the
corresponding hydroxy-acid, the lactone was dissolved in hot dilute
potasi-ium hydroxide, the solution cooled, acidified, and extracted
several times with pure ether. The ethereal solution was carefully
dried and concentrated, when it was noticed that, at a certain con-
centration, a crystalline acid commenced to separate from the boiling
ethereal solution, and the amount increased considerably on standing.
After recrystallising twice from ether, the acid was quite pure, aud
yielded the following results on analysis :

0-1212 gave 0-2700 CO.^ and 00959 K.p. C = 60-7 ; H = 8-8.
CgH^j^O.j requires C = 60-8; H = 8-8 per cent.

The basicity of the acid was determined by titration with N/IO-
sodium hydroxide, when 0-2221 neutralised 00556 NaOH, whereas
this amount of a monobasic acid, CgH^^Og, should neutralise
00562 NaOH.

cia-l-Methyloyclohexan-S-ol-b-carboxylic acid melts at 138 — 139*^ and
decomposes slowly at 140°, but much more rapidly at 150°.

It is very readily soluble in water, but sparingly so in ether, and
separates from its solution in the latter solvent, on concentrating, as

THE REDUCTION OF 5-HYDROXY-M-TOLUIC ACID. 1899

a soft, crystalline mass consisting of pearly plates, which do not lose
their lustre on exposure to air. In this respect it whows a marked
dili'eieuce from the behaviour of the <ra«s-acid in the same
circumstances. Both the trans- and the cis-acids melt at the same
temperature (139°), but an intimate mixture of equal amounts
of the two isomerides shrinks at 115 \ and is almost melted at
120°. Again, the two acids exhibit a striking diiference in their
behaviour towards hydrobromic acid, by the action of which the trans-
acid, as already explained, is converted into a syrupy bromo-acid.
The c'tVacid dissolves readily in fuminy hydrobromic acid (saturated at
0°), and the solution soon begins to deposit crystals. After remaining
overnight, the whole was transferred to porous porcelain, and left
until the hydrobromic acid had been completely absorbed ; the residue
was then dried over sulphuric acid and solid potassium hydroxide in
a vacuum desiccator.

The colourless bromo-acid was purified by crystallisation from light
petroleum (b. p. 50 — 60°), and two different specimens gave the
following results on analysis :

0-2878 gave 0-2199 AgBr. Br = 36-8.
0-2869 „ 0-2448 AgBr. Br = 36-4.

CgHjgOgBr requires Br = 36-2 per cent.

cia-S-Bromo-l-me/hT/lcycloIiexane-d-carboxi/Hc acid melts at 90 — 92°,
and decomposes, with effervescence but with little change in colour, at
about 170°. It is very readily soluble in alcohol, ether, or benzene,
but somewhat less so in light petroleum, from which it separates in
brilliant prisms or, if the hot concentrated solution is rapidly cooled,
in glistening, needle-shaped leaflets.

It is a comparatively stable substance, and is only gradually de-
composed on boiling with water.

l-Methylcyc\ohexan-3-one-5-carbox)/lic Acid,
CH,<nn5::?,5^>CH.CO,H.

-co CH

In preparing this acid, chromic acid (5 grams), dissolved in a little
water, was gradually added to ethyl l-methylc^c^ohexan-3-ol-5-
carboxylate (10 grams) dissolved in acetic acid (10 c.c), care being
taken that the temperature did not rise above 40°.

After about three hours, the product was mixed with very dilute
sulphuric acid, extracted with ether, the ethereal solution washed
well with water and then with sodium carbonate, dried, and
evaporated.

The residue yielded, on repeated fractionation, ethyl \-methylcyc\o-

1900 THE RKDUCTION OF 5-HYDROXY-M-TOLUIC ACID.

hexan-S-one-o-carboxi/laf^ as a colourless oil distilling at 138 — 140°/I5
mm. :

0-141 1 gave 0-3366 CO, and 01128 H,0. C = 64-9; H = 8-9.
CjoH^gOg requires C = 65"2 ; H = 8-7 per cent.

In order to obtain the free acid, this ester (15 grams) was digested
■with dilute hydrochloric acid (150 c.c. of 5 per cent.) in a reflux
apparatus, the condenser of which was removed from time to time to
allow the alcohol to escape. The clear solution was saturated with
ammonium sulphate, when an oil separated which was extracted several
times with ether, the ethereal solution was then dried, evaporated,
and the colourless syrup distilled :

0-1651 gave 0-3737 CO., and 0-1173 H.p. C = 61-7; H = 7-9.

0-1320 „ 0-2980 CO2 „ 0-0931 HgO. C = 61-6 ; H = 7-8.
C^Hj^Og requires C = 61-5; H = 7-7 per cent.

\-Mefh?/lc.yc\ohexan-3-one-5-cai-boxyliG acid is a viscid syrup, which
distils at 192°/15 mm., and a strong solution of which in water clouds
on cooling. The titration of the acid with iVyiO-sodium hydroxide
yielded the following results :

0-2064 neutralised 0*052 NaOH. whereas this amount of a monobasic
acid, CgHjgOg, should neutralise 0-(i53 NaOH.

The aqueous solution of the acid did not yield a crystalline semi-
carbazone on the addition of sodium acetate and semicarbazide hydro-
chloride even on standing for several hours, but, on the other hand, a
crystalline oxime was readily obtained.

In order to prepare this, the acid (2 grams), dissolved in a
little water, was mixed with a strong solution of hydroxylamine
hydrochloride (4 grams) and potassium hydroxide (6 grams) and
left for several hours. The alkaline solution was acidified, repeatedly
extracted with ether, the ethereal solution dried and evaporated, when
a colourless syrup remained which gradually crystallised.

The mass was left in contact with porous porcelain until quite free
from oil, and then recrystallised from ether :

0-1755 gave 11-8 c.c. N2 at 15° and 764 mm. N = 7-9.
CglljjOgN requires N = 8-2 per cent.

3-Oxiviino-l->neth/lcyc\ohexan-5-carboxi/lic acid is readily soluble
in warm, but much less so in cold, ether, and separates from this
solvent in minute prii^ms, melting at 142".

The authors are indebted to the Carnegie Trust and to the
Chemical Society for grants which have largely defrayed the cost of
this investigation.

The Schunck Laboratory,
The University,
Man<;hestek.

THE FORMATION AND REACTIONS OF IMINO-COMPOUNDS. 1901

C(JX. — TJie Formation and Reactions of Lnino-com-
pounds. Part XI. The Formation of l-Imi)io-2-
cyanoayoXopentane from Adiponitrile.

By JocELYN Field Thorpe.

It has been already shown that open-chain compounds containing
two nitrile groups separated by four carbon atoms tend readily to
pass into derivatives of the five-membered ring when they are treated
in alcoholic solution with a trace of sodium ethoxide or of a sodium
compound which dissociates in alcohol, the two instances illustrating
this generalisation being the transformation of ethyl a8-dicyanovalerate
into ethyl 2-imino-3-cyanocyc/opentane-l-carboxylate (this vol., 685),
CH/CH^-CN _^ CH. — CH(CN) ^

CHo-CH(CN)-CO,Et CH2-CH(C02EtK *

and the production of ^-imino-a-cyanohydrindene from o-phenylene-
diacetonitrile (Trans., 1908, 93, 176),

c.-k.<ch::cs -^ c.h,<-j:CH,->c:nh,

In order, therefore, to show that this reaction is of general applica-
tion when applied to the form ition of the cycZopentane ring, it remained
to prove that adiponitrile passed with equal readiness into 1-imino-
2-cyanocye/opentane,

I ^ - — >■ I - -/C NH.

CH.-CH./CN CH2-CH(CN)

Experiment showed that this reaction toqji place with great ease,
and that it was only necessary to heat an alcoholic solution of the
dinitrile containing a trace of sodium ethoxide for a short time on the
water-bath in order to transform it completely into the cyclic imino-
nitrile.

The adiponitrile used in these experiments was prepared according
to the directions of Henry (Btdl. Acad. roy. Belg., 1901, 7, 367) by
the action of alcoholic potaissium cyanide on aS-di-iodobutane,

CH^I-CH.-CHg-CH.I.
After several methods had been tried for the preparation of this iodo-
compound in a pure condition, the process recommended by von Braun
(Ber., 1906, 39, 4357) was ultimately found to give the best results.
This process starts with ay-dibromopropane, CHoBr'CH^'CH.jBr, which
is converted into a-bi'omo-y-phenoxypropane, CH.,Br*CH2'CH./0Ph,
by the action of sodium phenoxide. This compound is then converted
into y-phenoxybutyronitrile, CN'CHo'CHg'CH^-OPh, by the action of

1902 THORPE : THE FORMATION AND

potassium cyanide, and reduced by means of alcohol and sodium to
S-phenoxybutylamine, NH^-CHrCH^-CH.-CH.-OPh. The amine is
then converted by means of benzoyl chloride into its benzoyl deriv-
ative, which, on distillation with phosphorus pentachloride, is
transformed into a chloro-8-phenoxybutane,

CH.,Cl-CH./CH,>-CH./OPh.
Sodium iodide in alcohol then converts this chloro-ether into
a-iodo-S-phenoxybutane, CHgl'CH^'CHg'CHj'OPh, which is trans-
formed into aS-di-iodobutane on heating with hydriodic acid at 100°
for six hours.

ah-Dicyanohutane (Adiponitrile), CN-CHg'CHg'CHj'OHg'CN,

This substance was prepared by the action of alcoholic potassium
cyanide on a8-di-iodobutane, the process adopted being as follows.
Twenty-six grams of pure potassium cyanide were dissolved in as little
water as possible, and the solution, after being mixed with three times
its volume of alcohol, heated to boiling. Fifty grams of aS-di-iodo-
butane were then diluted with an equal volume of alcohol, heated to
boiling, and gradually added to the hot alcoholic potassium cyanide.
The reaction was fairly vigorous, and was completed by heating the
mixture on the water-bath for one hour^ when water was added to the
cool solution and the precipitated oil extracted by ether. The ethereal
extract was washed with water to remove alcohol, and then thoroughly
shaken with dilute hydrochloric acid, being finally dried and evaporated.
The residual oil was then carefully fractionated under 20 mm. pressure,
and the fi-action boiling at 180 — 182° collected :

0-1863 gave 0-4563 CO2 and 0-1258 H^O. 0 = 6678; H = 7-49.
CgHgNg reqtiires 0 = 66-7 ; H = 7--l per cent.

The washing with hydrochloric acid in the above pi'eparation was
found to be necessary, owing to the production of a certain proportion
of l-imino-2-cyanoc?/cZopentane by the alcoholic potassium cyanide.
The action of hydrochloric acid converts the imino-compound into the
corresponding ketone, which for the most part remains dissolved in
the dilute hydrochloric acid, and can be recovered by saturating the
solution with ammonium sulphate and extracting with ether. The
amount of imino-compound formed in the reaction depends on the
quantity of water used to dissolve the potassium cyanide. If no water
is used and the interaction of the di-iodide and potassium cyanide is
carried out in absolute alcohol, the formation of the imino-compound
cannot be detected. The process under these conditions takes, how-
ever, a considerable time for completion, and it is advisable to employ
the conditions given above and remove any imino-compound formed in
the manner stated. The observation is, however, of importance, since

REACTIONS OF IMINO-COMl'OUNDS. F \KT XI. 1908

it shows that when potassium cyanide is used in a solvent in whicli it
dues Dob dissociate, the production of the imino-nitrile does not take
place.

CH./CH(CNV ,,.^,^^
l-Imino-'2-ci/cmocyv\openiane, ' " '>L.r>Jll.

The conver.-^ion of aS-dicyanobutane into l-imino-2-cyanoc/y(;^opentane
isi readily effected by boiling an alcoholic solution of the dinitiile con-
taining a trace of sodium ethoxide. The conditions found to give the
best result were as follows. Five grams of the dinitrile were mixed
with 20 c.c. of absolute alcohol in a flask fitted with a reflux con-
denser, and a piece of clean sodium about the size of a grain of wheat
added. The sodium rapidly dissolved, and the solution, which became
pale yellow, was then heated on the water-bath for one hour. The
imino-nitrile, which separated from the solution on cooling, was collected
and purified by recrystallisation from benzene, when it was obtained
in long, flattened needles, melting at 147° (compare Best and Thorpe,
this vol., 709) :

0-1897 gave 0-4648 CO. and 0-1288 H^O. C = 6G-81 ; H = 7-54.
CgHgNg requires C = 66-7; H = 7-4 per cent.

The above method was found more convenient than using a solution
of sodium ethoxide in the manner desciibed in the conversion of
o-phenylenediacetonitrile into /8-imin>a-eyanohydrindene {loc. cit.),
although the change can be effected equally well by that means. The
small amount of reduction caused by the nascent hydrogen does not
apparently affect the yield of the imino-compound, which was found
to be practically the same by both methods. From the 5 grams of
aS-dicyanobutane used in the experiment, 42 grams of crude 1-imino-
2-cyanocyc/opi-ntane were obtained.

Ttie identity of the imino-compound was established by converting
it, by the action of dilute hydrochloric acid, into 2-cyanoc?/c^opeutanone,
and preparing the characteristic semicarbazone of this substance, which
melts and decomposes at 190° (compare this vol., 709).

Much of the expense entailed by this research has been met by
grants from the Government Grant Committee of the Royal Society,
and from the Research Fund of the Chemical Society, for which I
desire to express my indebtedness.

The IJniversitv,

Manchester.

H)04 JONES AND TASKER: THE ACTION OF

CCXl. — The Action of Mercaptans on Acid Chlorides.
Part I. Oxalyl Chloride ; the Mono- and Di-
thio-oxalates*

By Humphrey Owen Jones and Hubert Sanderson Tasker.

The alkyl mercaptans and their derivatives react in general with acid
acid chlorides to form esters of the corresponding thioacids ; thus, for
instance :

3RSH + PCI3 = P(SR)3 + 3HC1.

The final products of the reaction depend on the stability or in-
stability of the ester formed, and if it is unstable, on its manner of
decomposition. From the stable esters it is possible to obtain
potassium salts by the action on them of alcoholic potasisium hydro-
sulphide, and these potassium salts have in some cases properties of
special interest.

The .simplest method of decomposition of phenyl thio-estei\s is by
the elimination of phenyl disulphide, and this gives rise to the possi-
bility of obtaining new oxides of common elements. Those salts, how-
ever, which are of this nature appear to avoid decomposition in the
simple and normal manner.

Oxalyl chloride was prepared at first by a modification of the method
used by Fauconnier {Conipt. rend., 1892, 114, 122). Two gram-
molecules of phosphorus pentachloride and one gram-molecule of ethyl
oxalate were heated to 150 — 160° in sealed tubes and the product was
distilled. The fraction boiling at 70 — 75° contained the largest
percentage of ox tlyl chloride, but contained also phosphorus trichloride
and phosphoryl chloride, as well as as-dichloroethane. Further
purification, however, by distillation or precipitation of the oxalyl
chloride with dry pyridine was found to be impracticable.

The action of sodium phenylmercaptide on oxalyl chloride was
at first investigated in the hope of obtaining a new oxide of carbon,
C.^O.,. No definite gaseous product, however, was obtained from the
reaction, and the only solid products, apart from sodium chloride, were
phenyl disulphide , tripheuyl trithiophosphite, and triphenyl trithio-
phosphate.

Later, oxalyl chloride was obtained pure by Staudinger's method
(Ber., 1908, 41, 3558), and these experiments were repeated. A

* Preliminary notes on portions of this work have aheady appeared (Proc. Cnmb.
Phil. Soc, 1909, 15, 94 ; Proc, 1908, 24, 271).

MERCAPTANS ON ACID CHLORIDES. FAllT I. 1905

small quantity of carbon monoxide was produced togetlier wiLli .sodium
chloride, phenyl disulphide in small quantity, and a substance whicli
crystallised from alcohol in small, yellow needles.

If lead phenylmercaptide in ether suspension was used instead of
the sodium salt, the reaction was less vigorous, and there was no pro-
duction of gas or of phenyl disulphide, the only products being lead
chloride and the yellow compound ; this was presumed to be phenyl-
dithio-oxalate, the reaction taking place thus :

(COCl), + Pb(S-C6H5).3 - (C0-S-C,H,)2 + PbCl..

Phenyl dithio-oxalate is best prepared by the action of one gram-
molecule of oxalyl chloride on two of phenyl mercaptan. The reaction
starts in the cold, and a brisk evolution of hydrogen chloride takes
place. A yellow colour is produced on mixing the liquids, which
eventually solidify to a crystalline, yellow mass.

On ci-ystallisation from alcohol, sulphur-yellow, prismatic needles,
melting at 119 — 120°, are obtained, which are readily soluble in ether
or light petroleum :

0-2857 gave 0-6402 CO2 and 00951 H.p. C = 61-l ; H = 3-7.
C,4Hjq02S2 requires 0=61-31 ; H = 3-65 per cent.

Treatment with hot potassium hydroxide solution converts the ester
into potassium phenylmercaptide and potassium oxalate.

The ester distils unchanged under the atmospheric pressure, but is
decomposed by concentrated sulphuric acid, giving carbon monoxide
and a brownish-purple colour, which is a characteristic test for phenyl
disulphide.

On being heated with sodium to a temperature of 200 — 300°, the
substance chars and yields carbon monoxide.

The yellow colour of phenyl dithio-oxalate persists after repeated
recrystallisation and treatment in solution with animal charcoal.

Ethyl dithio-oxalate is prepared by mixing one gram-molecule of
oxalyl chloride with two of ethyl mercaptan in the cold. The liquid
becomes yellow, and hydrogen chloride is evolved. The mixture is
heated gently to expel any excess of either of the reacting substances,
and, on cooling, sets to a yellow, crystalline mass with a characteristic
and, to some, a nauseating odour. On crystallisation from ether,
yellow needles are obtained, which melt at 27^ — 27 5°, and distil
unchanged at 235° ; the spontaneous solidification of the crude mass
thus evidences the remarkable purity of the substance. Its colour,
although its existence is undeniable, is not so intense as that of the
phenyl ester :

0-1826 gave 0-2694 COg and 0-0883 H.p. C = 40-3; H = 5-3.
(CO'S'CoHr,).! requires C = 40-45 ; H = 5-6 per cent.

1906 .KIXES AND TASKKP. : TllK ACTION OF

Melhifl Dithio-iixalate. — Mwtliyl mercaptan was passed into oxalyl
cliloiide, when a yellow colovir was produced and hydrogen chloride
was evolved. On shaking the liquid with water, pale yellow crystals
of methyl dithio-oxalate, melting at 81 — 82°, t-eparated. In a later
preparation, crystals were actually deposited from the reaction liquid,
and, when crystallised from light petroleum, separated in small rhombs,
melting at 82"5 — 835°. The odour of this ester is very objection-
able.

Treatment with aqueous potassium hydroxide gave potassium
oxalate and methyl mercaptan :

0-3211 gave 0-3755 CO2 and O-llTQJIgO. C = 319; H = 4-08.
(CO-S-CH3)2 requires C = 32-0 ; H = 4-00 per cent.

Projiyl Dithio-oxalate. — This substance was prepared from oxalyl
chloride and propyl mercaptan precisely in the same manner as the
ethyl ester. At the ordinary temperature it is a yellow liquid
boiling at 158°/15 mm. :

0-2121 gave 0-4755 BaSO^. S = 30-8.

(CO'S'CgH-)^ requires S = 31-G per cent.

isoAmyl dithio-oxalate was prepared similarly from oxalyl chloride
and jsoamyl mercaptan. It is a yellow liquid, boiling at 206°/19 mm. :

0-2565 gave 0-4510 BaS04. S = 24-15.

(CO"S*C5H^j)2 requires S = 24-4 per cent.

Potassium Dithio-oxalate. — By the action of an equivalent quantity
of alcoholic potassium hydrosulphide on phenyl or ethyl dithio-oxalate,
also in alcoholic solution, the alkyl mercaptan is formed, and a white,
crystalline precipitate of potassium dithio-oxalate is obtained, which
may be collected and washed free of potassium hydrosulphide with
alcohol :

0-2195 gave 0-0950 CO2. C=ll-8.

0-1185 „ 0-2833 BaSO^. 8 = 327.

0-2063 „ 0-1795 K2SO4. K = 39-01.

C2O2S2K2 requires C= 12-1 ; S = 32-3; K = 39-4 per cent.

This salt i.s very soluble in water to a yellow solution, which on
evaporation on a water-bath deposits large, colourless prisms. After
recrystallisation, the salt appears to become less stable, and, on keep-
ing, turns bi'own with, however, no formation of sulphide.

If dilute sulphuric acid is added to a solution of potassium dithio-
oxalate, hydrogen sulphide is evolved, and a yellow, amorphous solid
is precipitated, which is not sulphur. The identity and properties of
this substance are now under investigation.

The solution also gives the following characteristic reactions with
various metallic salts :

MERCAPTANS ON ACID CFILOl'.IDES. PART I.

1907

Silver nitrate Oranj^e in-eciiiitate, (luickly turning black.

Lead acetate Oranj^o" jiroei'iitate, turning blaek on standing.

Mercunms nitrate I'lack precijjitate.

IVIerciiric chloride Pale yellow precipitate, stable on boiling.

]>isniuth nitrate Light y«-llo\v pieci])itate, turning dark brown on

boiling.

Cadmium chloride Pale yellow jirecipitate.

Copi)er sulphate ]Jark biown precipitate, soluble in excess of the

reagent to a dark green solution. This de-
posits a black prccijiitate on boiling.

Antimony chloride Yellow ]necipitate, turning brick-red on boiling.

Stannic ,, Light yellow colour in the cold. On boiling, a

precipitate, which turns from white to dark
brown.

Stannous ,, Reddish-brown colour, giving a d.nk brown

precijiitate on boiling.

Ferrous sulphate 'I A brownish-jiink coloration, giving on long

Ferric chloride J standing a brown precipitate.

Zinc suliihate Pale j'ellow coloration.

Nickel ,, Deep magenta coloration which is stable on

boiling. This most characteristic reaction is
dealt with more I'ully below.

Cobalt nitrate Deep reddish-brown coloration.

llangai'.ese sulphate Yellowi-^h-brown coloration.

Calcium chloride No precipitate in neutral solution. On addition

of ammonia there is precipitation of calcium
oxalate, sulphide rennuning in solution.

Palladium chloride Deep brown coloration. l>iown pj'ecii>itate on

standing.

Platinous ,, Keddish-brown coloration.

Platinic chloride and .sodium

carbonate Reddish-brown coloration, decjiening on

standing.

It is probable that the sulphide of the heavy metal is prodnced in
all cases where decompcsition occurs on boiling.

Potassium Nickelodithio-oxalate. — Equal weights of potassium
dithio-oxalate and nickel sulphate crystals were mixed in concentrated
solutions. There was a copious separation of small, almost black
needles, which exhibited an iridescence like that of potassium per-
manganate crystals. On recrystallisation from water, another form is
at times obtained in dark red octahedra, the composition of which has
been proved to be identical with that of the needles. The conditions
necessary to the formation of the octahedra have not, however, been
thoroughly determined.

A solution of these crystals does not give at once the usual tests for
nickel in solution. Sodium hydroxide solution changes the colour to a
greyish-brown, and nickel hydroxide precipitates only after some time.
Nickel sulphide also is precipitated very slowly on addition of potassium
hydrosulphide. Mercuric chloride gives a yellow precipitate, which
appears to be mercuric dithio-oxalate, leaving nickel in solution.

These facts suggest that the substance is potas-sium nickelodithio-
oxalate, and the structural formula KS-CO-CO-S-Ni-S-CO'CO-SK
is suggested :

1908 JOXES AND TASKER: THE ACTION OF

0-2097 gave 0-0979 CO.^. C = 12-78.

0-1974 „ 0-4960 BaSO^. S = 34-4.

C^O^SJvoNi requires C = 12-74; S = 34-0 per cent.

It is probable that those metals (iron and cobalt) which give similar
colorations with potassium dithio-oxalate form compounds of the
same type. These, however, are very soluble, and do not crystallise so
well as does the nickel compound.

The sensitiveness of these colours as tests for the presence in solution
of iron, nickel, cobalt, or dithio-oxalate was determined.

The colour effect can be used to detect nickel at a dilution of one
part of nickel in 40,000,000 of water if sufficient of the solution is
used to fill a large beaker, and one part in 8,000,000 can be
detected readily in a test-tube. The colour is about three times as
intense as that of potassium permanganate, and half as intense as that
of rosaniline, if the concentrations are calculated weight for weight.

The cobalt coloration is just as intense as that of nickel, and at a
dilution of one part of cobalt in 4,000,000 is about identical with the
colour produced by the addition of potassium thiocyanate to a solution
of ferric chloride containing one part of iron in 400,000. It will
therefore be seen that the formation of these colorations constitutes a
test remarkably delicate in consideration of the fact that they depend
on the formation of a complex ion in dilute solution.

The iron coloration was just perceptible at a strength of 1 in 100,000
of iron.

The nickel coloration could be detected in a solution of potassium
dithio-oxalate of the strength of 1 in 100,000.

The cobalt salt is much more stable than that of nickel. It decom-
poses on standing in solution much more slowly, and the coloration is
comparatively little destroyed by the addition of hydrochloric acid or
potassium cyanide. The nickel coloration, on the other hand, is
destroyed slowly by dilute hydrochloric acid, but at once by excess of
concentrated acid. Potassium cyanide also quickly discharges it.

This fact makes it possible to detect cobalt in a mixture
containing 10 per cent, of cobalt and 90 per cent, of nickel. On
adding potassium dithio-oxalate to the solution, a deep purple colora-
tion is obtained, but on addilion of excess of potassium cyanide the
purple coloration disappears and the solution remains brown.

It will be seen from statements made above that the presence of
iron does not interfere with the detection of nickel and cobalt in
dilute .solutions.

Ammonium dithio-oxalate is prepared by the action of alcoholic
ammonium hydrosulphide on phenyl dithio-oxalate. It is a crystalline
solid, which gives the characteristic tests for dithio-oxalates, but is
decomposed by heating its solution on the water-bath.

MERCAPTANS ON ACID CHLORIDES. PART I. 1909

It may be conveniently mentioned heie that, with tlie piopai-ation
of the compound CO^ as object, the action of nickel carbonyl on
oxalyl chloride was examined. When the substances react in the
liquid state, the evolution of gas is very rapid, and the reaction
mixture falls in temperature.

The gas evolved appears to be carbon monoxide, and nickel
chloride is deposited. This was confirmed by allowing the substances
to react in the gaseous state. Two bulbs of equal volume, each
surrounded by a bath and each connected with a mercury manometer,
were respectively filled with the vapours of nickel carbonyl and oxalyl
chloride. The bulbs were connected by a tube fitted with a tap,
which was closed before the bulbs wei'e filled. The pressure in each
bulb having been noted, the tap was opened, and the gases thus
allowed to mix. The pressure was read from time to time, until it
ceased to increase.*

If the reaction takes place in accordance with the equation
Ni(C0)4 + (C0C1)2 - NiClg + 6C0,
the final pressure will be three times as great as the initial pressure.

Two experiments, in which the following results were obtained, may
be quoted as typical :

Pressure of Pressure of

vapour of Ni(C0)4. vapour of (C0C1)„. Final pressure.
34 mm. 39 ram. 109 mm.

52 ,, 59 ,, 158 ,,

Thus it seems that the above equation represents the course of the
reaction, and hence it may be concluded that the CgO^ formed
momentarily is so unstable that it at once decomposes to give two
molecules of carbon monoxide in the cold.

The colour and other optical properties of the compounds here
described and of other sulphur compounds are being investigated.

The expenses of this investigation were partly defrayed by a grant
from the Government Grant Committee of the lloyal Society, for
which the authors ai-e glad to make this grateful acknowledgment.

University Chemical Laboratory,
Cambridge.

* This apparatus is convenient for the investigation of reactions between vapours,
and will be described more fully in another communication.

VOL. XCV. () i^

1910 TASKER AND JONES: THE ACTION OF

CCXIl. — The Action of Mcrcaptans on Acid Chlorides.
Part II. The Acid Chlorides of Phosphorus,
Sidphur, and Nitrogen.

By Hubert Sanderson Tasker and Humphrey Owen Jones.

The presence of pliospliorus trichloride and jDliosplioryl chloride in
crude oxalyl chloride resulted, as has been shown in the preceding
paper, in the formation of triphenyl trithiophosphite and triphenyl
trithiophosphate when the liquid was allowed to react with sodium
phenylmercaptide.

Schwarze {J. 2"'- CJiem., 1874, [ii], 10, 222) claimed that he
obtained triphenyl trithiophosphate by the action of phosphoryl
chloride on phenyl mercaptau, ascribing to it the melting point 72°.

Michaelis {Ber., 1907, 40, 3419) has investigated the properties
of triphenyl trithiophosphite and triphenyl trithiophosphate, and
finds that their melting points are 77° and 115° respectively. He
suggests that Schwarze's product was merely phenyl disulphide.
If this be so, as is improbable, for the melting point of phenyl
disu.lphide is 61°, it becomes likely that the reaction may give an
interesting redvxction product of phosphoryl chloride, thus :
POCI3 + 2CVH5-SH = POCl + (Cglir/ S)o + 2HC1.

This point has been investigated, and results seem to show that
Michaelis's surmise was incorrect, although his general results were
confirmed. Incidentally, it was found that triphenyl trithiophosphite
can be oxidised to triphenyl trithiophosphate by potassium di-
chromate and sulphuric acid, or by nitric acid. It forms no
additive product with methyl iodide or hydrogen chloride. The
interaction of phenyl mercaptan and phosphoryl chloride in mole-
cular proportions at 100° resulted in the production of a mixture
of triphenyl trithiophosphate and i^henyl disulphide. The two
products could be completely separated by crystallisation from
alcohol. All attempts to isolate the hypothetical compound POCl
failed, and it is iDrobable that phenyl disulphide is formed in the
reduction of phosphoryl chloride to phosphorus trichloride, thus:
POCI3 + 2C6H5-SH = H2O + PCI3 + (C(;H^'S)o.

The water would then form phosphoric acid with the excess of
phosphoryl chloride, and the phosphorus trichloride would probably
be carried off at the temperature of the reaction in the streams of
hydrogen chloride which are evolved.

It thus seems probable that Schwarze's comjDOund was triphenyl
trithiophosphate, as his analyses go to prove, the low melting point
being accounted for by the contamination with phenyl disulphide.

MERCAPIANS UN ACID CHLOIUDKS. I'AKl' 11. 1911

The Acid Chlorides of Sulphur.

Holmberg {Anncdcn, 1908, 359, 81) has stated that sulphuryl
chloride reacts with alkyl mercaptans to give the corresponding
alkyl disulphide, sulphur dioxide, and hydrogen chloride, thus :

2RSH + SOoClo = RoSg + SOo + 2HC1.

This result has been confirmed for phenyl mercaptan. By using
lead phenyhnercaptide, however, or phenyl mercaptan in ethereal
solution, evidence was obtained for the transitory existence of an
unstable phenyl dithiosulphate.

Sulphuryl chloride in ethereal solution was added to lead phenyl-
mercaptide at the ordinary temperature. Sulphur dioxide was
evolved at once, and the residue was found to consist of lead
chloride and phenyl disulphide.

When, however, the reaction was carried out in a freezing
mixture, the formation of lead chloride was detected by the change
in colour of the lead phenylmercaptide, but the solution became
reddish-yellow, and no gas was evolved. On warming the solution,
however, or allowing it to evaporate, the colour disappeared, sulphur
dioxide and phenyl disulphide being obtained.

There seems little doubt that phenyl dithiosulphate is formed
in solution, but it was found impossible to isolate it. The reaction
could then be represented thus :

SO..CI0 + Pb(S-C,,H5)., = PbClo + SOo(S-CoH3)..
SO,(S-C,H,), = SO2 + (S-CcHs).,.

The behaviour was similar when an ethereal solution of phenyl
mercaptan reacted with sulphuryl chloride at low temperatures.

These considerations made the study of the behaviour of thionyl
chloride with phenyl mercaptan and its derivatives one of especial
interest, for an analogous reaction might be expected to give rise
to a new oxide of sulphur, SO, thus :

SOCI2+ 2CcH5-SH = SO(S-C„H5)2 + 2HC1.

SO(S-C,H5),-SO + (S-CoH5)2.

The expectation, too, was strengthened by the fact that a similar
but paler transient colour was noticed when phenyl mercaptan or
lead phenylmercaptide was allowed to react with thionyl chloride
in ethereal solution at a low temperature.

The gaseous products of the reaction were therefore subjected
to examination.

One gram-molecule of thionyl chloride was allowed to react with
two of phenyl mercaptan at 0° or at other temperatures down to
— 70°, and the gases evolved were swept by means of a s-treim of

(J K 2

1012 TASKER AND JONES: TUE ACTION OF

dry hydrogen through U -tubes cooled to -70°, so that the gases
might be liquefied.

llydrogen chloride was obtained, and sulphur dioxide was
detected in large quantity, both by its odour and by its boiling
point. This indicated that the decomposition of thionyl chloride
involves the participation of more than one molecule, and the
simplest hypotheses for the reaction become :

(1) 4C6H5-SH + 2SOCI2 = 4HC1 + 2(C6H5-S)2 + SO.^ + S
and

(2) eCeHj-SH + SSOClo = 6HC1 + 3(CoH5-S)2 + SOo + SoO.
The latter hypothesis would involve the formation of another new

oxide of sulphur, SoO.

The reduction of thionyl chloride by nickel carbonyl was found
to throw light on the problem by analogy. These substances
interact vigorously in the cold; sulphur dioxide and carbon
monoxide are evolved, and a brown mass remains which consists
of nickel chloride and sulphur — it being possible to extract the
Latter by solution in carbon disuljDhide. The reaction, although
so vigorous, lowered the temperature of the reaction mixture.

It was found impossible, however, in the case of the reaction with
phenyl mercaptan to extract sulphur from the residue.

It was therefore decided to collect the gases evolved, and to
determine their total acidity, and also the extent to which they
could reduce iodine.

ri Grams of thionyl chloride were allowed to react with 7'o
grams of johenyl mercaptan in a distilling flask at a low tem-
perature. The gases evolved were swept by means of a stream
of dry hydrogen through an empty wash-bottle and two U-tubes
into 200 c.c. of T-sodium hydroxide solution.

It was possible, by surrounding the U-tubcs with freezing
mixtures, to estimate approximately the boiling points of the gases
evolved.

When violent reaction had ceased, the temperature of the reaction
llask was raised until the residue melted and ceased to evolve gas.
The residue at 60° was a clear, yellow liquid, which deposited
phenyl disulphide on cooling. This could be collected, and the
viscous liquid so obtained continued for some time to deposit small
quantities of phenyl disvilphide.

In addition to this yellow oil and phenyl disulphide, there
appeared drops of a less dense and more mobile liquid, which
was identified as water by the coloration of anhydrous copper
sulphate and by its action on sodium. It seemed to be a product
of the reaction, for it invariably appeared in spite of special
precautions which were taken to dry the hydrogen used. Its

MERCAl'IAXS ()\ AOID rULOIil DES. WWW 11. lf)13

.iniount. ronld not l)o est iinalcd, owing to llio small (|U;in(itv formed,
and the large excess of the otlier residual producfs.

By cooling the U -tubes, hydrogen chloride and sulphnr dioxide
were identified by their boiling points, but there was no evidence
of any other volatile product boiling above — 70°.

The sodium hydroxide solution was titrated first with i)'/10-sul-
phuric acid, and then with ^V/10-silver nitrate, to determine the
amount of hydrogen chloride evolved. Sulphur dioxide was
estimated by titration of the neutral solution with standard iodine
solution.

Two experiments were made, and the quantity of hydrogen
chloride estimated differed by only 2 per cent., showing that the
gases were thoroughly swept out of the apparatus. As a mean
of the two experiments, 2"55 grams of hydrogen chloride and 0"777
gram of sulphur dioxide were prodviced by the interaction of 4"1
grams of thionyl chloride and 7'3 grams of phenyl mercaptan.

The first hypothetical equation demands 2'45 grams of liydrogen
chloride and 1'06 grams of sulphiir dioxide, whilst the second
requires 2"45 grams of hydrogen chloride and 0"71 gram of sulphur
dioxide.

Low, rather than high, readings would be expected, and the fact
that the sulphur dioxide results are relatively high tends to dis-
countenance the validity of the second equation.

In these equations, too, the possible presence and volatility of
the compound SoO has been ignored. Its presence would be
expected at least to double the power of the products to reduce
iodine, so that the observed reading would fall very far short of
that required.

Nor did the solution on qualitative examination show any
evidence for the existence in it of a salt coi'rcsponding with a new
oxide of sulphur.

Examination of the residual mass gave further evidence in
support of the first equation.

The liquid obtained after collecting the phenyl disulphide which
separated was distilled under diminished pressure. Between 180°
and 220°/ 10 mm. phenyl disulphide distilled over, and an amor-
phous, sticky, brown mass remained behind. Phenyl disulphide,
when distilled alone, does not decompose, and leaves no residue.

Analyses of two specimens of the liquid gave the following
results :

0-2203 gave 0-4005 COo and 0-0710 HoO. C = 49-57; H = 3-3.

0-2112 „ 0-3890 COg „ 0-0650 HoO. C = 50-0; H = 3-42.
(CgHr,)oS4 requires C = 5ri; H = 3-55 per cent.
(CgH,);S3 „ C-57-6; H = 40

llll-l TASKER ANP JONES: THE ACTION OF

It seemed probable that (lie liquid is either phenyl tetra-
sulphide which still holds a little phenyl di sulphide in solution, or
else a diflicultly crystallisable solution of sulphur in phenyl di-
sulphide.

Phenyl tetrasulpuide is described as a viscid, yellow oil, which
decomposes on distillation into sulphur and phenyl disulphide.
The properties of the oil obtained closely correspond with these.

A solution of sulphur in phenyl disulphide in the pi'oportions
corresponding with (0(3115)284 was prepared. It solidified, on
cooling-, to a hard, cream-coloured mass, the appearance of which
had nothing- in common with that of the liquid obtained from the
reaction.

Thus an equation can be written to include the phenyl tetra-
sulphide which seems to be formed :

8C6H5'SH + 4SOClo = 8HC1 + 2SO2 + 3(CcH5-S)2 + (C6H5)2S4.

In support of this, it was found that 14-6 grams of phenyl
mercaptan and 8 grams of thionyl chloride produced 10-65 grams
of phenyl disulphide, whilst the above equation requires 11-27
grams.

Thus the equation represents the reaction fairly well, except for
the water, a small quantity of which is invariably formed.

At this jDoint our attention was drawn to a statement by
Holmberg (loc. cit.), to the effect that alkyl mercaptans react with
thionyl chloride in accordance with the general equation :
4RSH + socio = R2S2 + R2S3 + H.O + 2H01.

This hypothesis accounts for the formation of water, but takes
no account of the evolution of sulphur dioxide, and since phenyl
trisulphide is a solid, it would demand that the residual mass
should become completely solid at the ordinary temperature.
Reference to the experiments already quoted suggested that the
two reactions might proceed simultaneously, for sulphur dioxide
was always produced in quantity smaller than that required by
the equation proposed.

Further experiments were devised to ascertain whether either
of the two hypotheses correctly represents the reaction under any
special conditions.

It will be convenient if the two equations be henceforth referred
to as A and B, thus :

(A) SOgH^- SH + 4SOOI2 = 8H01 + 2S0, + 3(OeH,3-S)2 + {Cf;E.r;)Si-

(B) 40cH5-SH + SOCI2 = (06H5-S)2 + (C6H5)2S3 + H2O H- 2H01.

A weighed quantity of thionyl chloride was allowed to react
with an excess of lead phenylmercaptide in a IJ-tiibe. A continual
stream of dry air, freed from carbon dioxide, swept the gases

MERCAPTANS ON AC[D CHLORIDES. PART TT. 1015

evolved intx) a measured volurPie of standard sodmm. hydroxide
solution. After sweeping with air for eight hours, it was found that
no more gas was absorbed by the alkali. The sodium hydroxide
solution was neutralised and titrated with standard iodine to
estimate the sulphur dioxide, when it was found that 1'955 grams
of thionyl chloride gave 0'473 gram of sulphur dioxide. If thionyl
chloride is decomposed in accordance with cqxiation A, 0'526 gram
of sulpluir dioxide should be evolved. In this case, by the use
of a metallic derivative of phenyl mercaptan, the formation of
water as demanded by equation B was prevented. The satisfactory
agreement obtained (considering the nature of the experiment)
indicates that in this case a modification of equation A would
adequately represent the reaction.

Unfortunately, an experiment of similar nature with phenyl
mercaptan itself, in place of the lead derivative, was found to be
impracticable, for the stream of air carries over into the sodium
hydroxide considerable quantities of that one of the reactive
liquids which happens to be present in excess. Another method
was therefore devised.

The hydrogen chloride and sulphiir dioxide produced were
estimated by heating the total products of the reaction with a
measured excess of standard alkali and by titration of the solution
obtained. The two liquids were weighed, and the effect of an
excess of either on the titrations was allowed for.

The suitability of the method for discrimination between
equations A and B depends on the proportions of the reacting
substances used. The proportion of 8 gram-molecules of phenyl
mercaptan to 4 gram-molecules of thionyl chloride demands,
according to A, 12 equivalents of alkali and 4 equivalents of
iodine, and exactly the same quantities are required according
to B. Thus, if the substances are used in this proportion, no
discriminative result will be obtained. A more decisive result
can be obtained by using 16 gram-molecules of phenyl mercaptan
to 4 of thionyl chloride. Equation A will then require 20 equi-
valents of alkali and 12 of iodine (one gram-molecule of phenyl
mercaptan neutralises one gram-molecule of sodium hydroxide,
and reduces one gram-atom of iodine), whilst B will require 8
equivalents of alkali and no iodine.

This was the proportion used in the experiments. Standard
solutions of phenyl mercaptan and of thionyl chloride in dry ether
were made. The required volume of each was measured into a
stoppered bottle, and the bottle was shaken from time to time. A
measured excess of iV-sodium hydroxide solution was then a<l<le(l, and,
after further shaking, the whole was titrated, first with acid, and then

lfU()

TASKER AND JONES: THE ACTION OF

with iodine. Prelim in a vy experiments proved that tlie titrations
were sufficiently accurate under tliese conditions. Two experiments
may be quoted to illustrate the results obtained.

Thioiiyl

Phenyl

chloride,

nicrcaptaii,

Equation A

Equation />'

gram.

gram.

Jvo;ulings.

re(|iiu'es

requires

0-178

0-664

7-1 c.c. iV-alkali

7-5 c.c.

3-0 c.c.

0*477 gram iodine

0y73 gram

—

0-171

0-632

.5-8 c.c. iV-alkali

7-15 c.c.

2-85 c.c.

0-395 gram iodine

0-515 gram

—

These results seem to indicate that both reactions, represented
by equations A and B, take place simultaneously.

In order to carry out the same type of experiment, using the
pure substances instead of the ethereal sohitions, a special device
was adopted.

One of the substances was weighed into a large flask fitted with
two tap funnels, one small and the other large. The small funnel,
containing about the right amount of the other substance, was
weighed before the reaction, and weighed again when the reaction
was over and the liquid had been allowed to enter the flask. The
large funnel contained 100 c.c. of i\"-sodivim hydroxide solution.
The liquid in the small funnel was allowed to run by small
instalments into the flask, the evolved gases being allowed to
escape through the alkali in the large funnel so as to absorb all
the hydrogen chloride and sulphur dioxide.

The pressure in the flask was easily regulated by heating and
cooling. The reaction being quite finished, the sodium hydroxide
solution was allowed to run into the flask, and the contents were
shaken. The solution was then filtered through glass wool, made
up to 200 or 250 c.c, and titrated with acid and iodine.

The results obtained are expressed, as before, in grams of iodine
required to oxidise the sulphur dioxide and phenyl mercaptan
and in c.c. of i\'-acid required to neutralise the sulphur dioxide,
phenyl mercaptan, and hydrogen chloride produced. The
theoretical amounts are calculated by finding the amount of alkali

Thionyl

Phenyl

chloride,

mercaptan,

Equation A

Equation B

grams.

grams.

Readings.

lequires

requires

1-984

1-742

54-8 c.c. iV-alkali

59-0 c.c.

588 c.c.

2-51 grams iodine

3-652 grams

3-23 grams

0-878

3-408

22-4 c.c. iV^-alkali

38-4 c.c.

16-3 c.c.

1-13 grams iodine

2-99 grams

0-205 gram

•2-1 S6

5-477

59-5 c.c. A'-alkali

68-2 c.c.

48-6 c.c.

2-75 grams iodine

3-6 grams

1 -5 grams

1-010.',

3-03

25-0 c.c. i\^-a]kali

41-5 c.c.

17-1 c.c.

0-85 grain iodine

3-11 grams

0-04 gram

MKRCAPTANS (^X AT'ID r'Ur/miDKS. I'Al'.T M. 1917

or iodine required by tlie reaction products (tlic reaction is assumed
to use up the siibstance not present in excess), and by adding to
these values the amounts required by the excess of the other
reacting substance.

The first experiment serves to show the limited accuracy of the
method, the calculated results being about the same for each
equation.

In the other cases, the observed value is always intermediate
between the two calculated values, and if a rough correction be
made for the losses as observed in experiment 1, the experimental
values are found to give the balance of evidence in favour of
equation A.

In experiments 2 and 4, the proportions taken are about those
demanded for equation B, and in these cases the reaction seems
to follow this equation to a greater extent than in 3, where there
is a larger proportional amount of thionyl chloride.

It is unfortunate that the addition of a further amount of
thionyl chloride renders the method no longer discriminative.

It must be concluded that the two different reactions take place
simultaneously. The projDortions in which the reacting substances
are present may be one of the factors which determine the ratio
of the extents to which the two reactions proceed.

Nitrosyl Chloride.

The behaviour of nitrosyl chloride with mercaptans is apparently
analogous to that of sulphuryl chloride.

When nitrosyl chloride is passed into phenyl mercaptan, the
liquid turns port-wine red, and hydrogen chloride is evolved. The
nitrosyl chloride is completely absorbed by the mercaptan, but the
coloured liquid rapidly evolves nitric oxide. If the introduction
of nitrosyl chloride is stopped, the colour gradually disappears with
slower and slower evolution of nitric oxide, and phenyl disulphide
finally separates out.

It would thus appear that the coloured and unstable phenyl
thionitrite is formed in solution, and that this decomposes to give
the final products of the reaction, thus :

C6H--SH + NOCl = IICl -f CoHj-SNO (unstable).
2C(.,H5-SNO = (C6H5-S)2 + 2N0.

It is, however, possible that the colour may be due to a direct
additive product of phenyl mercaptan and nitrosyl chloride. To
test this, nitrosyl chloride was allowed to react wilh an ethereal
suspension of lead phenylmercaptide. The red colour was again

191S THE ACTION OF MERCAPTANS ON ACID CHLORIDES.

produced, and lead chloride was left in suspension. Thus, a
compound such as

H

CI
cannot be responsible for the colour of the solution.

The unstable, intermediate product may be preserved some time
if the solution is kejot at a low temperature, but all attempts to
isolate it failed.

The corresponding ethyl and methyl compounds were obtained
in solution.

On passing nitrosyl chloride into an ethereal suspension of
mercury methylmercaptide, Hg(S'CH3)2, the liquid became
brownish-pink, and mercuric chloride was formed. The colour
rapidly disappeared on standing and nitric oxide was evolved.

This behaviour is quite analogous to that observed in the case
of lead phenylmercaptide.

The action of ethyl mercaptan on nitrosyl chloride at a low
temperature resulted at first quite normally in the formation of a
magnificent cherry-red colour, and in the evolution of hydrogen
chloride. The red colour eventually disappeared with evolution of
nitric oxide. In a freezing mixture of solid carbon dioxide dis-
solved in ether, however, a white, crystalline solid was deposited in
small quantity. This was separated from the solution and re-
crystallised from alcohol. It was eventually identified as hydroxyl-
amine hydrochloi'ide, and must be the product of a side-reaction
involving the reduction of the nitrosyl chloride.

The unstable, coloured thionitrites show two absorption bands,
one sharply defined and broad in the yellowish-green, and the other
narrower and diffuse in the green portion of the spectrum. The
substitution of an alkyl group of high molecular weight for one of
low molecular weight shifts the bands towards the red end of the
spectrum.

The expenses of this investigation were partly defrayed by a
grant from the Government Grant Committee of the Royal Society,
for which the authors are glad to make this grateful acknowledg-
ment.

UxivKP.siTT Chemical Labouatort,
Cambridge.

OONTRIBUTIONS TO THK TFTEDRV OF SOLUTIONS. 1019

CCXIII. — Contributions to tJic Theory of Solutions.

By John Holmes and Philip John Sageman.

The nature of the forces operative in solution, and more particularly
in aqueous sohition, has, in recent years, been the subject of much
experimental investip^ation on the part of both chemists and
physicists. A ci'itical survey of the theories which have from
time to time been put forward to explain the property of solution
leaves, however, much to be desired, and leads to the conclusion
that they severally afford only plausible explanations for a narrow
circle of phenomena, and are incapable of general application.

Of these theories, the two which are by far the most important
are the " Hydrate theory," first promulgated by Mendeleeff, and
the " Dissociation theory " of Arrhenius.

Mendeleeff attempted to explain the phenomena peculiar to
aqueous solutions by the production and subsequent dissociation of
hydrates at different concentrations. With the advent of cryoscopic
methods of determining molecular weights, and the interpretation of
the results of electrical conductivity experiments by Arrhenius,
the '"' Hydrate theory " fell for a time into disrepute, but recently
it has in a modified form received such supjDort that Findlay
(A?})K Rejyorfs, 1907, 4, 21) states that "hydrate formation is now
accepted probably by the majority of physical chemists."

Solution in water, therefore, which almost invariably results in
a marked contraction in volume, is generally regarded as being of
the nature of combination, and hydration of the molecules of the
dissolved substance increases with the dilution (Jones and Uhler,
Amer. Chew. ./., 1907, 37, 126, 244).

The endeavours of the many investigators in this field are far
from conclusive, however, regarding the existence of such complexes,
and much contradictory evidence from widely different sources is
forthcoming in this connexion. For instance, Morse, Frazer, and
Lovelace (^Amer. Chem. J., 1907, 37, 360) conclude, from cryoscopic
work on aqueous dextrose solutions, that, even at the freezing point,
dextrose exists in the anhydrous condition, and does not combine
with the solvent. Kremann and Kerschbaum {Monotsh., 1907, 28,
911), from a consideration of the specific heat of the mixture
H2SO4 — HoO on cooling through a wide range of temperature,
conclude that the heat developed on mixing must be ascribed to
other causes than to the formation of a hydrate of sulphuric acid.
Similar conclusions are drawn in the case of sodium sulphate in
aqueous solution by Marie and Marquis (Com/pt. rend., 1903, 136,

lfV20 HOLMES AND SAOEMAN :

CtS4) from tlie continuous solubility curves given by sohitions of
sodium chloride in aqueous sodium sulphate at temperatures
including the transition temperatures of crystallised sodium sulphate
in water and in sodium chloride solutions. Perman also deduces
the non-existence of hydrated complexes in aqueous solutions of
sodium sulphate and potassium sulphate from the results of
experiments on the influence of these salts on the vapour pressure
of aqueous ammonia solutions (Trans., 1902, 81, 489).

Apart from such anomalies, however, a hydrate theory affords
but little assistance in explaining the varied properties of other
than aqueous mixtures, which represent only one branch of the
problem of solution, and in order to arrive at a better under-
standing of these forces, it is necessary to seek other explanations
of the same phenomena.

According to Arrhenius (Zeitsch. phi/sikal. Cheni., 1887, 1, 631),
the molecular condition of a dissolved salt must be regarded as
that of a more or less dissociated substance, and the properties of
salt solutions are considered to be consistent with the presence of
free ions. The molecular conductivity of such solutions increases
with the dilution, and, according to this theory, the degree of
dissociation can be calculated from the electrical conductivity or
the results of cryoscopic molecular weight determinations.
Arrhenius's theory has been subjected to much adverse criticism
in recent years, and many experimental results are deemed
irreconcilable with the theory of ionic dissociation (see Kahlenberg,
J. Physical Cheui., 1901, 5, 339, and Tra?is. Faraday Soc, 1905, 1,
42; Armstrong, Proc. Boy. Soc, 1907, A, 79, 586; 1908, A, 81, 80;
Lincoln, J. Physical Chem., 1899, 3, 457; and others). The most
important objection to the theory is its failure to interpret the
case of concentrated solutions, together with the fact that it is
iintenable in the case of non-aqueous mixtures.

It may not be permissible to apply the laws which are valid for
gases to non-gaseous substances, but there is no reason for assuming
that the forces which determine the coherence of the molecule in
the several states of aggregation differ otherwise than in degree.
Under constant conditions of temperature and pressure, and in
the absence of chemical change, the gaseous molecule retains its
individuality when mixed with other gaseous molecules, and the
breaking down of molecular complexes and ionic dissociation on
admixture in this the simplest state of aggregation are equally
unnecessary for the explanation of gaseous phenomena.

According to the electrical theory of the constitution of matter,
the atom is never electrically neutral, and the phenomena apper-
taining to electrically charged bodies may be expected to occur

CONTRIBUTIONS TO THE THEORY OF SOLUTIONS. 1921

between the nuclei of different atoms. In these circumstances, the
molecule, which is a congeries of such atoms, must also be elec-
trically active, and may be regarded as consisting of a nucleus of
great density, in which the atoms composing the molecule are
swayed and controlled with mathematical precision in their several
orbits according to the intensity of their respective electrical
charges; the resultant of these several interacting forces would, in
the case of similar molecules, create an atmosphere or sphere of
influence (the molecular co-volume of Traube, Ber., 1907, 40, 723,
736), the extent of which will depend on the magnitude of the
resultant, and the consequent repulsive force operative between
adjacent envelopes. It is reasonable to suppose that the equilibrium
thus determined would remain constant under similar conditions,
but at once be disturbed by admixture with molecules of different
electrical constitution, and possessing maybe a greater or less
sphere of influence. If the attractive force between different
molecules in a mixture is so great as to cause the rupture of the
intervening envelopes, a molecule with wholly different properties
will be formed, whose sphere of activity will be dependent on the
latent resultant force of the new atomic arrangement, but so long
as no chemical change occurs, the molecules in a mixtvire may be
expected to retain their respective individualities — the only change
consequent on mixing being an increase or decrease in the initial
volumes resulting from the new conditions of equilibrium neces-
sitated by the interaction of differently electrifled bodies, and a
readjustment of the dimensions of the interspaces.

In the gaseous state of aggregation, the individual molecules arc
so far removed from the sphere of action of their neighbours that
they are scarcely influenced by molecular forces, and obey the
general laws of mechanics. Gases alone, for instance, possess the
property of unlimited intermiscibility, and the johysical properties
of a gaseous mixture can be deduced within a near approach to
accuracy from the properties of the several ingredients. The
gaseous laws are, however, only approximate, and the pressure
exerted by a gaseous mixture does not always rigidly accord with
the sum of the initial pressures.

It is common knowledge, however, that in the case of liquids
and solutions there is associated with the intermingling a change in
the properties belonging to the constituents of the mixture, and
not only does the volume of the mixture invariably differ from the
sum of the initial volumes, but the specific rotation, specific heat,
refractive index, and other physical properties are not strictly
additive. The change in volume is perhaps capable of deter-
mination with greater precision than is the case with other physical

">

1922 HOLMES AND SAGEMAN :

properties, and it is from a study of these deviations from simple
additive relations that we hope to gain information concerning the
nature of the forces operative in solution, and the correlation of
physical properties with molecular structure.

The importance of change in volume in this connexion was noticed
as long ago as 1865 by Bussy and Buignet (^Anfi. Chim. Fhys., [iv],
4, 5), and they record the fact that the mixing of liquids results in
both volumetric and temperature changes, which may be positive
or negative according to the nature of the constituents of the
mixture. Various mixtures of liquids have been investigated by
Brown (Trans., 1881, 39, 202), Guthrie {Phil. Mag., 1884, [v], 18,
495), Linebarger {Amer. J. Set., 1896, [iv], 2, 226; see also Amer.
Chem. J., 1896, 18, 440), Thorpe and Rodger (Trans., 1897, 71,
367), and others, but apart from the fact that certain forces are
operative between heterogeneous molecules, no definite conclusions
have been drawn regarding the nature or magnitixde of these forces.
It is evident, however, from the experimental results that the
molecules which make up the mass of a substance in the liquid
state are capable of occupying a different volume, and as regards
their mean distances from each other are in a jDOsition of relative
equilibrium liable to change when the forces which influence them
change.

The behaviour of acetone and n-piopyl alcohol in aqueous
solution affords important evidence in this direction. There is
reason to believe that these liquids are similarly associated
(see Trans., 1906, 89, 1781), and have in consequence almost
identical molecular weights and molecular volumes. In these
circumstances, -f the volumetric changes were conditioned only by
an adjustment of spacing due to differences in the volumes of the
respective molecules, it would be expected that the change in
volume occurring in aqueous mixtures of these liquids would be
of the same magnitude. The fact that acetone yields with water
a contraction in volume in amount almost twice that obtained in
corresponding mixtures of /i-prop5'l alcohol proves, if we admit
similar association, that not only do intermolecular spaces exist,
but that each molecule contains a fixed amount of electrical energy,
or is subject to some combination of circumstances which assumes
all the appearances of electrical energy.

A theory regarding the condition of substances in solution as a
regular arrangement of molecules in a comparative state of rest,
each possessing within its sphere of activity latent positive and
negative electrical affinities, was first promulgated by Grotthiiss to
explain the phenomena of electrolysis. The complete abandon-
ment of this theory, and also of the electrochemical theory of

CONTRIBUTIONS TO THE THEORY OK SOLUTIONS. 1928

Berzelius, by chemists renders a reintroduction of similar hypotheses
difficult, and justifiable only in so far as they are capable of
affording explanations of common phenomena which are not forth-
coming in the case of existing theories.

Our present object is to develop, in the direction already
indicated, the electrical theory of matter as applied to the liquid
state of aggregation, and endeavour to establish the entity of
the liquid molecule under normal conditions.

Volume Changes Accompanying Chemical Change.

Before proceeding to a consideration of the forces operative in
mixtures of liquids, it seemed desirable further to investigate (see
Trans., 1907, 91, 1608) the nature of the volumetric changes
occux'ring in aqueous mixtures in which these changes can be
referred to the action of chemical forces.

According to the electrical theory of the nature of the molecule,
the volume change can no longer be attributed to forces inherent
in the molecules of the initial constituents of the mixture, but
will be dependent on the physical nature and behaviour of the
compounds formed. When an alkali is neutralised by an acid, for
instance, the resulting volume of the mixture is conditioned only
by the solution volume of the resulting salt, and this change may
be positive or negative according to the nature of the salt. It
is found that, although the admixture in aqueous solution of many
acids, such as sulphuric acid, phosphoric acid, and oxalic acid,
with their salts, results in a marked change in volume, the corre-
sponding change occurring when the same salts are mixed with
the basic hydrates is so small as to be negligible, in comparison
with the relatively large volumetric changes obtained on
neutralisation.

The following mixtures were made with the object of ascer-
taining the nature of the change in volume resulting from a
gradual neutralising of basic hydrates with various acids in dilute
aqueous solution. The densities of the different solutions and
mixtures were determined at 15°/ 15° in a pyknometer having a
capacity of about 70 c.c, and the change in volume is calculated
from the several weights and densities.

1924

HOLMES AND SAOEMAN

(i) Mi.iliires of Aqueous Sodium Hydroxide and, SaljiJiiiric Acid

(cijijvox. noi'mal).

Density ol' sodium hydroxide solution -rOJiiTC.
,," sulphuric acid ,, =1-03209.

Kquivalcnt volumes lOONaOH aq. : lOOH.SO^ aq.

Volume of sodium

^'^olume of snlphuiii:

Increase in

hydroxiiie solution.

acid solution.

volume after mixin

100

iG-r.o

+ 0-195

100

20-22

0-239

100

33-02

0-390

100

49-50

0-589

100

81-12

0-973

100

99-26

1-198

100

198-96

1-518

(ii) J/irdires of Aqueous Fotassiui// Hydroxide and II tjdrochloric
Acid {ciffrox. normal).

Density of potassium hydroxide .solution = 1 -0500]. •

,, hydrochloric acid ,, —1-01793.

Equivalent volumes lOOKOH aq. : lOOHCl aq.

Volume of

potassium

hydroxide solution.

100

100

100

100

100

Volume of

hydrochloric

acid solution.

16-75

33-16

66-90

100-46

150-40

Increase in
volume after mixitij
+ 0-311
0-632
1-309
2-001
2-027

(iii) Mixtures of Aqueous Ammonia and, H tjdrochloric Acid
(ajpfrox. normal).

Density of ammonia solution - 0-99270.

J, hydrochloric acid ,, =1-01794.

Equivalent volumes IOONH3 aip : lOOHCl aq.

Volume of Volume of hydrochloric Decrease in
ammonia solution. acid solution. volume after mixing'.

100 19-12 -0-123

100 33-44 0-215

100 66-68 0-431

100 100-09 0-644

100 . 150-40 0-644

I

CONTRIBUTIONS TO THE THKORV OF SOI.UTIONS. 1025

(iv) Mixtures of Aqueous Barium Hydroxide and Hydrochloric
Acid (cippj-ox. 3 1 10-71 or ma I).

Density of barium hydroxide solution = 1 •02840.
,, hydrochloric acid ,, =1'00555.

E(iuivalcnt volumes 100Ba(OH)o aq. : lOOliCl iuj.

Volume of Volume of hydrochloric Increase in
liaiium hydroxide solution, acid solution. volume after mi.xing.

100 16-72 +0-101

100 33-41 0-204

100 C6-30 0-404

100 99-97 0-613

100 150-24 0-616

(v) Mixtures of Aqiicuuis Sodium Hydroxide a7ul Acetic Acid
(appro X. normal).

Density of sodium hydroxide solution = 1 -04377.
,, acetic acid ,, =1-00908.

Equivalent volumes lOONaOH a(i. : 99-2C2H40o atj.

Volume of sod;

ium

Volume of acetic

Increase in

hydroxide solul

:ion.

acid solution.

voli

irme after mixing.

100

17-02

+ 0-157

100

33-87

0-329

100

67-01

0-659

100

100-9.^.

1-007

100

150-41

rooi

(vi) Mix/ tires of Aqveom Sodium Hydroxide and. Tartaric Acid
{(iqiprox. normal).

Density of sodium hydroxide solution = 1-04376.
,, tartaric acid ,, =1-03391.

Equivalent volumes lOONaOH aq. : IOO-4O4H6O,; aq.

Volume of sodium Volume of tartaric lncrea.se in

hydroxide solution. acid solution. volume after mixing.

100 17-30 +0-160

100 33-70 0-313

100 67-56 0-641

100 101-30 0 974

100 151-50 1-016

(vii) 3lixtures of Aqueous Sodium Hydroxide and Oxalic Acid.

Densitv of sodium hvdroxide solution = 1-04376.
(o.) ,," oxalic aciil „ =1-02621.

Equivaknt volumes lOONaOH aq. : 82-5H2Co04 aq.

Volume of sodium A'olumc of oxalic Increase in

hydroxide solution. acid solution. volume after mixing.

100 20-74 +0-251

100 41-08 0-502

100 81-93 1-014

100 101-25 1-150

VOL. XCV.

6

1926

HOLMES AND SAGEMAN

(vii) Mixtures of Aqueous Sodium Hydroxide and Oxalic Acid
(continued).

(8.) Densitj' of oxalic acid solutiou = l "01756.
Equivalent volumes lOONaOH aq. : I25H2C2O4 aq.

Volume of sodium

Volume of oxalic

Increase in

hydroxide solution.

acid solution.

voh

ime after mixing

100

21-34

+ 0-160

100

42-01

0-324

100

83-89

0-667

100

126-57

1014

100

189-69

1-307

2-0

5 1-0

Fig. 1.

/

*7

V

7 5/

c^^^^^^^
j^^^^^^

^

/

v

#

y^^

0 100 200

Volume of acid solution added (0 100 volumes of basic solution.

From the graphical representation of these results (Fig. 1) it is
evident that the change in volume produced on neutralising a base
with an acid is directly proportional to the quantity of salt formed.
The view that this increase or decrease in volume is conditioned

CONTRIBUTIONS TO THE THEORY OF SOLUTIONS, 1927

by the solution volume of the salt is supported by the fact that,
within wide limits, the volume change is independent of concen-
tration. For instance, in the case of mixtures of iV -sodium
hydroxide with oxalic acid solutions of dififerent strengths, prac-
tically the same increase in volume is obtained in corresponding
molecular mixtures in the two sets of experiments (see Fig. 1).
The same applies to other mixtures, and might be deduced from
the fact that the solution volume of salts in water changes but
little with the concentration.

Wlien excess of acid is present, the vohime change depends on
the nature of the acid. Secondary interactions occur, as we know,
in mixtures of sulphuric acid and oxalic acid with their salts
in aqueous solution, and these are represented by curves differing
in slope beyond the point of neutralisation according to the degree
of physical change. When no physical interaction takes place
between the acid and its salts, the change in volume beyond the
point of neutralisation must be represented by a line parallel to
the base line. This is exemplified in aqueous mixtures of bases
with hydrochloric acid, and we should expect that mixtures of
hydrochloric acid with its salts would, under these conditions, give
no volume change.

The following mixtures were made in order to verify this
conclusion :

Mixtures of Sodium Chloride and Hydrochloric Acid in Aqueous

Solution.

Density of hydrochloric acid solution = 1 •09372.
(a.) ,, sodium chloride ,, =1'13192.

Equiniolecular volumes (gaseous) lOONaCl aq. : 60-4HC1 aq.

Volume of

liydrochloric acid solution mixed with Change

100 vohimes of sodium chloride solution. in volume.

7-69 +0-02

14-93 +001

20 18 0-00

30-36 0-00

60-70 -0-01

121-43 -0-02

(j3. ) Density of sodium chloride solution = 1 06874.
E(juimolecular volumes (gaseous) lOONaCl aq. : 307HC1 aq.

5-26 0 00

10-12 0-00

15-43 000

30-72 -0-01

61-53 -0-02

It is difficult to see how these simple facts of solution are to be
explained on the assumption of hydrate formation or ionic dis-

fi L 2

1J>2S HOLMES AND SAGEMAN :

sociatioii, or, since the volume cliaiigc at any degree of dilution
is dependent on the solution vohime of the salt formed, hy any
theory not acknowledging the individuality of the liquid molecule
under normal conditions.

Molecular Comjilexity in the Liquid State.

In order to form a conception of the equilibrium existing
between two liquids mutually miscible without change in their
chemical nature, we may assume the molecules to be severally
represented by spheres of different degrees of electrification. If
volume changes were conditioned only by the resultant of the
quasi-electrical forces inherent in the molecules — acting at a dis-
tance— the maximum deviation in volume from the theoretical,
when the number of molecules in a mixture remains constant,
would occur when they are mixed together in equal proportions,
and it would be possible to calculate the magnitude of the change
for other mixtures from the expression :

| = a(100-a)A',*
where " ^ is the change in volume, and " a "' the percentage of
one set of molecules in the mixture. Attention has been drawn
in previous communications to the influence of the weights and
volumes of the interacting molecules on this normal change in
volume at different concentrations, but if we consider only the
cumulative effect of all physical forces when increasing quantities
of one set of molecules are added to a fixed number of other
molecules, it is evident that the resulting physical change, whatever
its nature, must be capable of representation by an unbroken
curve.

The curves shown in Fig. 2 I'epresent the volumetric changes
which occur on mixing water with sulphuric acid, methyl alcohol,
and pyi'idine respectively, and are typical of those obtained in the
case of aqueous mixtures of inorganic and organic liquids generally.

The base line represents gram-molecules of water mixed with
one gram-molecule of each liquid (referred to the gaseous state)
'under constant conditions of temperature and pressure.

In arranging the material dealing with this subject, compara-
tively few cases have been noticed in which the physical changes
interpreted as above fail to fall on smooth curves, and these have,
on further investigation, been found to be due to experimental
errors in the density determinations. Pyridine and water mixtures
afford a case in point. Dunstan, Thole, and Hunt (Trans., 1907,

For the apiilicatioii of this exjircssioii to ai|Ui;oii>i iiii.\tur.s, and to mixliucs of
sulphuric acid with its salts, see Trans., 1907, 91, 1606.

.?ONTlUnUTI()NS TO THE THEORY OF S()I,UTIOXS.

lf)2r)

I

91, 1728), ill the course of an investigation on the viscosity of
mixtures of these liquids, drew attention to apparent discontinuities
in the density curve, corresponding with similar discontinuities
in the viscosity curve, and deduced the existence of certain
hydrated complexes. More recently. Hartley, Thomas, and
Applebey (Trans., 1908, 93, 538), while engaged on the same
mixtures, point out discrepancies in the densities given by Dunstan,

Fl<:. 2.

^^ 3

^

,s^

^

J

t*^

f

.TT^

*/

\

-^

/ /

-rt»,RTl.EY,THOMA

; & AvpuEBey

/ /

/^

. DurfSr^N Tmole.

&HuNT

\ / /'

1 1 /'

¥

Gram-mokrahs of iratcr.

Thole, and Hunt, and fail to verify the discontinuities in question.
The pyridine-water curve in Fig. 2 represents the physical change
deduced from Hartley, Thomas, and Applebey 's figures, whilst the
experimental points of Dunstan, Thole, and Hunt are also given.

The existence of such discontinuities would at once di.^prove
the hypothesis on which we are attempting to explain these physical
changes, and it is satisfactory to note that a repetition of ihe work

1030 HOLMES AND SAGEMAN :

by Dunstaii and Tliole (Trans., 1908, 93, 561) affords a contraction
curve which is practically coincident with that of Hartley, Thomas,
and Applebey.

An inspection of the above curves indicates that the rate of
physical change rapidly diminishes when the proportion of water
molecules (referred to the gaseous state) present in the mixture
becomes greater than 50 per cent., and it was this circumstance
which first suggested similar complexity in the case of these
liquids, and by reason of the disturbing influences of mass and
volume on the magnitude of the change in volume consequent
on the existence of intermolecular spaces, subsequently led to the
method of determining liquid complexities adopted by one of us
in a previous communication (Holmes, Trans., 1906, 89, 1780), and
which depends on the apparent maximum change in the volume of
the constituent of a mixture possessing the greater molecular
volume.

If, however, we disregard for a moment the relative masses and
volumes of the molecules in a mixture, and consider only the effect
of physical forces acting at a distance, we obtain, by substituting
different values for "$'' in the expression:

a + p

the following curves of volume change (Fig. 3) when increasing
quantities ()8) of one set of molecules are added to a fixed number
(a) of the other molecules.

It is apparent that various means are at our disposal for the
identification of an experimental curve as one of this order, and
for fixing the point on the curve corresponding with a mixture of
equal numbers of molecules. Perhaps the simplest is a graphical
lepresentation of the volume change plotted on a scale double
that of the molecular concentration as indicated on the base line,
when a tangential projection to the curve at this point will make
an angle of 45° with the ordinate.

Many mixtures are known which afford curves approximating
closely to this description, and those relating to aqueous mixtures
of methyl alcohol, acetic acid, and pyridine are repi-esented in
Fig. 4.

The corresponding curves yielded by other aqueous mixtures are
very similar in character, and add weight to our previous deduc-
tions regarding the absence of hydrate formation in solution. The
deviations from the theoretical physical curve we ascribe solely

• A modification of the expression ^ = a{lOG -a)K, which represents the curve of
volume change when the number of molecules in a mixture is constant.

CONTRIBUTIONS TO THE THEORY OF SOLUTIONS. 1931

to close-packing consequent on gravitational influences of mass
on the intermolecular spaces, the extent of distortion being
dependent on the relative volumes and masses of the molecules, and
also on the magnitude of the change in volume.

In the absence of means of determining the values of these
various constants in mixtures of liquids differing widely in their
relative densities, and maybe in their molecular volumes, we have
no alternative but to return to a consideration of the behaviour

Fin. .1.

2

0 1 2

Gram-molecules ")3" mixed \vith 1 gram-molecule "a."

of a mixture of spheres of different radii as previously dealt with
(Trans., 1906, 89, 1774).

If it be granted that the resultant of the forces inherent in the
nature of the several molecules reaches a maximum at or near a
mixture representing equal molecular proportions, it is evident
that in this mixture the distance between the centres of mass
of adjacent molecules will be either a maximum or a minimum,
according to the nature of the volume change. Any method,
therefore, which determines the quantities of the ingredients of
a mixture necessary for this purpose will afford a means of ascer-

19^2

HOLMES AND SAGEMAN :

taining the relative complexities of liquid molecules. With a
knowledge of the radii of the several molecular spheres, and since
we are at liberty to assume that the volume change influences
more in proportion the volume of the spheres of greater radii, it
would appear that the necessary information will be given by the
maximum difference between the initial and final proportions by

Fio. 4.

3

^■•

- '' '

/^

/>

Z'

"PyRlDlNfi

^^tTMYL

^ceTlC A

\LCOMOL

///

1

1 /

III

i'

i'

i'

■ '/

ijl
f

0 12 3

Gram-'inolecules of icater.

volume in a mixture of the constituent possessing the greater
molecular volume.

Except, perhaps, in the case of homologous series, the question
of deciding which molecule possesses the greater volume is open
to doubt. A consideration of the data afforded by aqueous mix-
tures of the r<-primary alcohols and aliphatic acids favours the
view that the above method of interpretation is valid in the.se
ca.ses, and the application of the same principle to other than

CONTRIBUTIONS TO THE THEORY OF SOLTTTIONR.

inj^8

aqueous mixtures gives strong support to the hypothesis that tlie
intermiscibility of liquids is a function of tlie molecular volume
{loc. cit.). This deduction, if correct, would go far in serving as a
basis for a simple mechanical theory of solution, and the following
series of mixtures were made with the view of obtaining further
evidence in this direction.

Mixtures of Aniline with Methyl Alcohol.

In the generality of cases, miscibility in aqueous solution is
accompanied by contraction in volume. There are many non-
aqueous mixtures also known in which contraction occiirs, and the
following mixtures of aniline with methyl alcohol are representa-
tive of this class.

The form of pyknonieter used for the determination of relative
densities was a modification of that described by Linebarger
(^Amer. J. Sci., 1896 [iv], 2, 226), one limb consisting of a capillary
tube, whilst the terminals were fitted with capillary connexions
and glass caps. The process of filling was conducted by means of
a pressure pump, air being passed through a sulphuric acid washer
into the weighing flask containing the liquid or mixture the
density of which was required, thereby causing it to pass over and
fill the pyknometer by way of the capillary limb. The pyknometer
was then kept for one hour in a thermostat, the contents of which
were agitated by a continuous stream of air-bubbles, and kept at
25° by means of a mercury-toluene regulator. The capacities of
the pyknometers used in these experiments measured by their
content of water at 25° were as follows :

Grams of water.

A 25-0312

B 24-9861

C 25-0020

The boiling point of the sample of methyl alcohol (Kahlbaum's)

was 64-8— 65-0°, and its density at 25°/ 25° was 0-79042. The

aniline had a boiling point of 184-0°, and a density at 25°/25° of

1-02060:

When the volume of aniline
is constant at 100 volumes.

Weights in vacimni. Dt-nsity of Relative Contraction

-^ % ini.xtnre volume of in voJunie

Aniline. Methyl alcohol. at '25°/2b^. methj'l alcohol, on mixing.

1. 2. 3. 4. ;-..

(i) 26-2428 2-?,96\ 1-00247 ir7Si OeSO

(ii) 24-149S 4-14SS 0-98815 2'2-173 1-147

(iii) 22-0566 5-8567 0-97358 34-271 1-607

(iv) 20-32.^2 6-9309 096312 44 051 1-917

(v) 17-6773 8-9755 0-94391 65-533 2-509

(vi) 14-5323 11-8654 /3-9174n 105-377 3302

1034

HOLMES AND SAGEMAN

Equimolecular volumes of the two liquids as given by the
quotients of the molecular weights (referred to the gaseous state)
by the relative densities at 25° are as 100 volumes aniline to
44"42 volumes methyl alcohol.

The curve in Fig. 5 represents the change in volume (column 5)

Fic

The hose line represents molecular proportions [referred to tlie gaseous state) of methyl
alcohol, ethyl alcohol, n-propyl alcohol, acetone, and ethyl acetate, mixed with
100 volumes of aniline a.nd 'methyl iodide respectively.

when increasing quantities of methyl alcohol (column 4) are mixed
with 100 volumes of aniline. By interpolating, the values were
obtained for the volume change at different molecular mixtures,
and from them were calculated the differences between the pro-
portion of aniline (as the more insoluble and, according to the

»

CONTRIBUTIONS TO THE THEORY OF SOLUTIONS. 1035

above hypothesis, possessing therefore the greater molecular
volume) in the initial and final volumes :

Molecular mixtnre (gaseous). Contraction in volume Difference between

^ ' ^ wiien the volume of the projiortioii of

Methyl aniline is constant aniliiit- in the initial

Aniline. alcohol. at 100 volumes. and final volumes.

1 0-2.'; 0-65 0-530

1 0-50 115 0-778

1 0-75 1-57 0-894

1 1-00 1-93 0-938

1 1-25 2-25 0-944

1 1-50 2-53 0-925

1 1-75 2-77 0-891

1 2-00 2-99 0-852

It is evident that the greatest difference between the proportion
of aniline in the initial and final volumes occurs at a mixture
closely approximating to equal numbers of molecules referred to
the gaseous state, thereby indicating that aniline possesses the
same molecular complexity as methyl alcohol. Inferentially,
therefore, aniline is similarly associated to water and the primary
alcohols and aliphatic acids, and its molecular volume at 25°, as
compared with water, is

93-096 1 . ^^

X = 5'06.

18-016 1-0206

As was noticed in the case of aqueous mixtures of the primary
alcohols and aliphatic acids (loc. cit.), the point of maximum
difference falls slightly beyond the mixture of equimolecular pro-
portions, a circumstance already explained by close-packing due
to differences in the radii of the molecular spheres of influence.

Mixtures of Methyl Iodide with Ethyl Alcohol, n-Pro'pyl Alcohol,

and Acetone.

In the case of non-aqueous mixtures, it often happens that a
volume is obtained, after mixing, which is greater than the sum
of the initial volumes of the constituents, and the following series
of mixtures were made with the view of ascertaining how far
the method we have adopted is applicable in these circumstances.

As a result of much preliminary work, it was found that the
w-primary alcohols and acetone gave relatively large increases in
volume when mixed with methyl iodide, and the opportunity was
offered of comparing the results thus obtained with those furnished
by the corresponding aqueous mixtures of these liquids.

The sample of methyl iodide was prepared from wood-naphtha,
carefully purified, and fractionated. Its boiling point was
42'3 — 42-6°. The sample of ethyl alcohol was prepared by
repeatedly treating rectified spirits of wine with powdered lime.

1930

HOLMES AND SAGEMAN :

whilst the ;/-pio]nl aKoliol and acetone were obtained from
Kahlbaum.

The capacities of the three ])yknometer.s, measured by their
content of mctliyl iodide at 25°, were as follows :

Grams of
methyl iodide.

A 56r)109

/.' 56 4091

a r)6-4413

The mean density of methyl iodide afforded by these figures is
therefore 2-25760 at 25°/25°.

Mixtures of Methyl Iodide tvith Etliyl Alcohol.

Boiling point of cthj^l alcohol = 78 'SS".
Density at 25725" ,, ,, = 078892.

Equimolecular volumes (gaseous) lOOCH.jI : 92-80C.,H„O.

When the
volume of methyl iodide
is constant at 100 volumes.

n vacuum.

Density

Relative

E-thyl

Methyl

of mixture

volume of

Increase in

alcoliol.

iodide.

at 25725°.

ethyl alcohol.

volume.

(i)

1-1348

56-9203

2-17391

5-705

0-216

(ii)

2-3045

56-5247

2 09768

11-667

0-346

(iii)

4-2561

50-9563

1-96530

23-902

0-567

fiv)

7-2165

42 0453

1-76365

49-116

0-863

(V)

9-3124

35 1057

1-61374

75-910

1-100

(vi)

10-5956

3r094.'5

1-52302

97-512

1-232

(vii)

14-2311

21-3744

1-28708

190-528

1-662

Mixtures of Methyl Iodide with n-I'ropyl Alcohol.

Boiling point of n-propyl alcohol = 97 -2 — 97 -4°.
Density at 257-25" „ ,, = 0-80206.

Equimolecular volumes (ga.seous) IOOCH3I : 119-06C;jH<,O.

WheTi the

volume of methyl

iodidrt is

Weigli

constant at 100 volumes.

A

s in vacuum.

Density of
mixture

Relative
vo'ume of

Increase
in

w-Propyl

Methyl

alcohol.

iodide.

at 25725°.

?i-)(ropyl alcohol.

volume.

(i) 1-5417

58-4232

2-15183

7-428

0-257

(ii 2-6795

54-5779

2-07387

13 819

0-386

(iii) 2-8880

56-1928

2-06') 4 9

14-466

0-398

(iv) 5-1682

48-4309

1-91127

30 037

0-689

(V) 8-3949

38-9151

1-69709

60 721

1-005

(vi) 10-4975

32-0-286

1 -.04939

92-255

1 212

fvii) 12 0036

28-2780

1-45640

119-483

1 -331

(viii) 15-4573

18-7997

I -23496

231-434

1-684

CONTRllJU'J'KXVS TO THE TIIEOKY OF SOLUTIONS. 1 087

mixtures of Methyl Iodide with Acetone.

Boiling i)oint of acetone -56 '9 — 57 "2".
Density at 25725° ,, = 0787f4.

E(iuinioIccular volumes (gaseous) IOOCH3I : n7'28C:;lI,;0.

When tl

lie

volume of nielh)

1 iodide is

constant at 100

\o

lunics.

"Weights

in

vacuum.

Density of

mixture
at 25725".

f

Relative \olunie
of acetone.

I:

in

N

Acetone.

M

ethyl iodide.

11 (Tease
volume.

U)

1-5266

57-2413

2-15008

7-651

0-246

(ii)

2-7681

55-1:398

2-06642

14-402

0-437

(iii)

4-9605

47-9377

1-91063

-29-686

0-817

(iv)

SI 690

39 6197

1-69857

59-106

1 -332

(V)

10-1997

32-2721

1-54552

90-670

1 -74:'.

(vi)

11-8551

27 9170

1-43775

121-826

2 077

(vii)

15 •5123

18-4745

1-20943

210-884

2-8-24

The following values for the volume change at different molecular
mixtures of these liquids with methyl iodide were determined from
the graphical representation of the results (Fig. 5), and from
them were calculated the differences between the proportion of
methyl iodide in the initial and final volumes :

Jlolecular

uii.\tui-e (gaseous).

Expanf

iion in volume

Difference between

, >■ ,

when the

volume of

■ methyl

the pre

(portion of

methyl

Ethyl

iodide is

constant at 100

iodide in

the initial

and tinnl

nlcohol,
/i-propyl

volumes in

its mixtu

res with :

volumes

of its mi.xtures with :

r

^

r-

^

diethyl alcohol,

Ethyl n

-Proi)yl

Ethyl

?t- Propyl

iodide, acetone.

alcohol. ;

ilcohol.

Acetone.

alcohol.

alcohol.

Acetone.

1 0-2

0-47

0-59

0-67

0-33

0-38

0-41

1 0-4

0-73

0-88

1-14

0-39

0-40

0 .'".2

1 0-5

0-84

1-02

1-33

0-39

0-40

0-52

1 0-6

0-93

1-09

1-49

0-38

0-37

0-51

1 0-8

1-08

1-23

1-79

0-35

0-32

0-47

1 1-0

1-21

1-33

203

0-32

0-28

0-43

From a consideration of these results, it is evident that the
greatest difference between the proportion of methyl iodide by
vohime in the initial and final volumes occurs when the number of
molecules of methyl iodide in the mixture is practically double
that of each of the other liquids, indicating that acetone possesses
the same molecular complexity as the 7i-primary alcohols — a result
already deduced from the volume changes afforded by aqueous
mixtures of these liquids — and that methyl iodide has twice this
complexity.

The molecular volume of methyl iodide at 25°, compared with
that of water at the same temperature, is therefore
M1-994X2
2-2576 X 18 OK)

1938 HOLMES AND SAGEMAN :

It will be noticed tliat in these cases where expansion in volume
occurs, the close-packing of the molecules causes the point of
maximum difference in the proportion of the liquid of greater
molecular volume to be displaced slightly in the direction opposite
to that observed when contraction takes place — a result which
was to be expected.

Mixtures of Methyl Iodide with Ethyl Acetate.

Similar mixtures were made with methyl iodide and ethyl
acetate, the results of which are as follows :

Boilin.a point of ethyl acetate = 77'0 — 77'3°.
Density at 25725° „ ., = 0-89350.

Equimolecukr volumes (gaseous) IOOCH3I : 155"91C4Hjj0.2.

When the
volume of methyl iodide
Weights in vacuum. is constant at 100 volumes.

^

Density of

^

Ethyl

Methyl

mixture

Relative volume

Increase

acetate.

iodide.

at 25725°.

of ethyl acetate.

in volume

(i) 2-3536

60-1754

2-11898

9-832

0-310

(ii) 4-4215

54-8778

2-00817

20-253

0-603

(iii) 7-0356

47-4884

1-86516

37-242

1-018

(iv) 9-3554

50-8072

1-74115

56-733

1-377

(v) 11-5193

37-0678

1-63724

78-118

1-698

(vi) 15-7150

26-4510

1-4-2218

149-346

2-412

These results, interpreted as above, indicate that ethyl acetate
is similarly associated to water and the r^-primary alcohols, and
that its molecular volume in the liquid state at 25°, compared with
water, is

88-064 =5.4"

0-8935 X 18-016 '"

In a previous communication, the property of solubility has been
compared to the behaviour of a mixture of inelastic spheres of
different radii. Liquids, for instance, having molecular volumes
approximating closely to one another are miscible in all propor-
tions, but when the distance between the centres of mass of
molecules of either constituent becomes so great as to allow the
smaller to pass through the interstitial spaces of the larger spheres,
mutual miscibility ceases, and the greater this factor, propor-
tionately less miscible the liquids become.

We do not presume, however, that the solubility of liquids in
water is a direct function of the molecular volume as determined
by the quotient of the molecular weight by density. The volume
so obtained comprises the true molecular volume defined by the
sphere of activity of the atoms composing the molecule (and of
which we know little), together with the outer envelope or molecular

CONTRIBUTIONS TO THE THEORV OF SOLUTIONS. 1939

co-volume created by the resultant of the quasi-electrical forces
inherent in each atomic arrangement, and which allows of the
diverse volume changes observed in mixtures of liquids. If relative
solubility were directly pi'oportional to the molecular volume so
determined, it would presuppose that no change occurred in the
volume of the interacting spheres after mixing. All experiments
prove, however, that such changes do occur, even iu the case of
substances possessing only slight solubilities, so that the relation
of the molecular spheres to each other changes with the degree
of physical change. When such volume changes are comparable
in the case of partially miscible liquids possessing approximately
the same molecular volume, a similar comparison is to be noticed
in their solubility factors. Thus, ethyl acetate and ethyl ether
yield considerable contractions in aqueous solution, and, having
molecular volumes at 22° of 5"4 and 5'8 compared with that of
water, are soluble in 100 volumes of water at this temperature to
the extent of 9'26 volumes and 8' 11 volumes respectively. Aniline,
on the other hand, with a molecular volume of 5'1, gives little
volume change with water, and, instead of possessing greater
solubility by reason of its smaller initial volume, is soluble only
to the extent of 3-48 volumes (Herz, Ber., 1898, 31, 2671, and
Bancroft, Phys. Rev., 1895, 3, 131).

It is probable that this change in the relative radii of the
several molecular spheres on mixing can be calculated within a
near approximation, but as in most cases the volume change is
small, the disturbing factor due to this circumstance is greatly
minimised, and, inasmuch as the relative volumes occupied by
liquid molecules must be represented by the quotient of the
molecular weight in the gaseous state by density, or a simple
multiple of this quantity (since it is inconceivable that the molecular
weight should be less in the liquid than in the gaseoi;s state),
sufficient latitude is afforded for allowances of this nature.

There is great probability, therefore, that, just as vapour
density determinations are indirectly of importance in fixing the
molecular weights of gases, so a knowledge of density and solu-
bility will also suffice for ascertaining relative complexity in the
liquid state.

It has already been shown that this method is roughly applicable
to carbon disulphide and other liquids the molecular volumes of
which have previously been given (Trans., 1906, 89, 1785), and
although these volumes, through lack of available data, were
compiled from densities at varying temperatures, the change is
so slight within small ranges of temperature that they may be
assumed to be sufficiently accurate for the purpose.

1040 HOLMES AND SAGEMAN :

For example, if methyl iodide were similarly associated to ^Yatcr,
its molecular volume at 25° would be

_X41-994 =3-49,
2-2576 X 18016

and it would be placed in the molecular volume table among the
lower alcohols and fatty acids which are miscible with water in all
proportions. If, however, we double the aggregation, the molecular
volume becomes 6" 98, which falls between the ascertained molecular
volumes (at the same temperature) of «-amyl alcohol (6'04) and
chloroform (8'93) — a position which agrees w'ith the gradation in
the solubility factors of these liquids in water (Rex, Zeitsch.
2ihysikal. Chem., 190G, 55, 355, and Herz, loc. cit.), and also with
its molecular volume as ascertained above by volume change
methods.

Heat Changes in Liquid Mixtures.

Just as we have reason to believe from the data at present at
our disposal that the intermiscibility of liquids may be explained
by a theory requiring the individuality of the molecules under
normal conditions and a knowledge of their relative volumes, so
it should be possible to explain other physical properties apper-
taining to liquid mixtures on the same hypothesis.

Miscibility of pure liquids with water not only results in a
contraction in volume, but heat also is produced. It is customary
to regard this evolution of heat as being analogous to the heat
of neutralisation of acids and bases, and capable of explanation
on the theory of hydrate formation. It is difficult, however, to
reconcile the fact that, in most cases, the neutralisation of an
acid by a base in aqueous solution resitlts in a relatively large
expansion in volume, whilst contraction usually accompanies the
mixing of pure liquids with water. In the first instance, the heat
evolved is undoubtedly due to chemical action, as a result of
which the initial molecules of a mixture are wholly disintegrated
and a new set of molecules produced. In the second case, the
heat evolved must be ascribed to friction between the several
envelopes or spheres of influence of the molecules consequent on
forces of attraction, which result in the diminution in volume.
In cases where contraction occurs we are obviously unable to draw
deductions regarding the molecular condition of liquids from the
mixture which yields a maximum of heat production, since the
close-packing of molecules due to gravitational influences of mass
on the interspaces must also cause friction and evolution of heat.
For instance, when increasing quantities of water are added to a
fixed volume of ethyl alcohol, although the rate of change of

CONTRIBUTIONS TO THE THEORY OF SOLUTIONS. lO-ll

heat production may be a maxiiniuii near the mixture of equal
proportions of molecules, careful experiments show that the greatest
evolution of heat occurs at a mixture approximating to the pro-
portions C.HoO,8HoO.

Again, mixtures of liquids are known in which heat is absorbed,
and we find in the generality of these cases that expansion in
volume results.

In another class of mixtures, of which those of chloroform and
ethyl alcohol are a type, heat is evolved in some mixtures and
absorbed in others, and although few data are here available
except those afforded by the work of Bussy and Buignet (loc. cit.),
these are undoubtedly instances of the gravitational influences of
mass on the interspaces causing a frictional evolution of heat,
which is greater in magnitude at some concentrations than the
heat absorbed as a result of the normal forces of repulsion inherent
to the molecules, and which in many mixtures of these liquids
results in an expansion in volume. Such peculiarities can only
obtain in mixtures in which the normal change in volume is
relatively small.

Few mixtures of liquids have hitherto been examined with the
view of ascertaining the law of the change of temperature with
concentration. The mixtures of methyl iodide with n-primary
alcohols, yielding as they do relatively large expansions in volume,
promised to afford valuable information in this direction.

In the following series of mixtures, the initial temperature of
each constituent was adjusted to 15°, which temperature approxi-
mated closely to that of the room, and the change in temperature
after mixing ascertained by means of a Schmidt and Haentsch
thermometer graduated to 0*1°. The volume of the mixture in
each case was about 30 c.c.

Mixtures of Methyl Iodide with Methyl Alcohol.

Molecul:

ar

Molecular

mixture

(gaseous).

T(

smpeiature

mixture

(gaseous).

Te

Methyl

Methyl

Methyl

Methyl

imperature

iodide.

alcohol.

change. ,

, iodide.

alcohol.

change.

1

0076

-4-0°

1

0-761

-6-8°

1

0-120

5-3

]

1-071

6-4

1

0-253

6-0

1

2-002

5-6

1

0-5-24

6-9

VOL. XCV. 6 M

1942

CONTRIBUTIONS TO THE THEORY OF SOLUTIONS.

Mixtures of Methyl Iodide with Ethyl Alcohol.

Molecular
mixture (gaseous).

Tom[)erature

change.

-5-2°

6-0

7-0

7-3

Molecular
inixturt' (gaseous).

Methyl
iodide.

1
1

1
1

Ethyl
alcoliol.
0-061
0-126
0-258
0-529

Methyl
iodide.

1

1

1

Ethyl
alcohol.
0-818
1-051
2 053

Temperature

change.

-6-8°

6-4

5-6

Mixtures of Methyl Iodide with n-Proyyl Alcohol.

Molecular
mixture (gaseous).

Methyl
iodide.

1

1

1

]

«- Propyl
alcohol.
0 062
0-116
0-122
0-252

Temperature
change.
-5-4°

6-2

6-3

7-5

Molecular
mixture (gaseous)

Methyl
iodide.

1

1

1

1

/i-Projiyl
alcoliol.
0-510
0-775
1-004
1-944

Temperature

change.

-8-0°

7-8

6-9

5-1

Mixtures of Methyl Iodide tvith n-Amyl Alcohol.

Molecular
mixture (gaseous).

Temperature

change.

-6-5°

7-8

8-1

Molecular
mixture (gaseous).

Methyl
iodide.

1
1
1

w-Am\d

alcohol.

0-121

0-239

0-493

Methyl
iodide.

1

1

/i-Aniyl

alcohol.

0-943

1-975

Temperature
change.
-6-9°
4-5

In each series the maximum fall in temperature occurs at an
admixture corresponding to two molecules of methyl iodide with
one molecule of each alcohol (referred to the gaseous state), a
result which confirms the complexities of these alcohols compared
with methyl iodide as deduced above from volume change experi-
ments.

The results of this investigation lend support to our previous
deductions that physical forces only are operative in solution,
and that theories requiring electrolytic dissociation, or combination
of solvent with solute, are unnecessary for understanding many
of the phenomena common to aqueous and non-aqueous mixtures.
We adhere to the view that the properties of both mixtures of
liquids and solutions are consistent with the entity of the liquid
molecule, and we venture to think that we have made out a prima
facie case for an electrical theory requiring only a knowledge of
liquid complexities for the elucidation of the simple facts associated

STUDIES IN PHOTOTUOPY AND THERMOTROPY. PART 1. 19^3

with the property of solution. Much experimental work is neces-
sary before such a theory could be regarded as established, but
we would suggest it at least as a working hypothesis for further
investigations in this field of research.

In conclusion, we desire to express our indebtedness to Sir
Edward Thorpe, C.B., F.R.S., for facilities afforded us in carrying
on this investigation.

The Government Labou-^touy,
London.

CCXIV. — Studies m Phototropy and Thcrmotropy.
Part I. Arylidene- and Naphtliylidene-amiyies.

By Alfred Senier and Frederick George Shepheard.

In a recent paper we described a series of Schiff's bases, salicylidene-
amines, one of which, salicylidcne-m-toluidine, was found to be
highly phototropic (this vol., 441). Under the influence of light
waves of high refrangibility, this compound was found to change
from pale yellow to orange, and when removed from that influence
to return to its original colour. The phenomenon was ascribed to
reversible isomeric change. We have continued this inquiry, and
now submit an account of further work, in which we have studied
a number of other salicylicleneamines and related compounds.

Including salicylidene-/«-toluidinc, we have now found five
compounds which exhibit phototropy. Looking at the constitution
of these, there does not appear to be any necessary relation between
the nature or the position of the substituents and the phototropic
property. They are all salicylidene dei'ivatives, but many such
derivatives are not phototropic, as is the case also with the
analogous o-hydroxynaphthylidene compounds which we have
examined. It may be noted that the phototropic property is
destroyed by the substitution of methoxyl for hydroxyl; further,
in the case of salicylidene-m-toluidine, by the substitution of
hydroxyl or chlorine for the methyl group, and, in salicylidene-
y-aminobenzoic acid, either by the substitution of chlorine or
methyl for the carboxyl group or by the conversion of the acid
into a metallic salt.

Early in this investigation it was observed that many of the
coloured bases became deeper in colour on heating, and that this
change, like phototropy, was reversible. The whole of the com-

6 M 2

104ji SENIER AND SHEPHEARD : STUDIES IN

pounds in hand were then subjected to an examination to obtain
further evidence, if possible, of this property. Their colour changes
were noted (1) between the ordinary temperature and the tempera-
ture just below their melting points, called " the higher tempera-
ture," and (2) between the ordinary temperature and the lowest
temjierature we could conveniently command, that of solid carbon
dioxide, called " the lower temperature." This led to the interesting
fact that most of the compounds exhibit this phenomenon. Among
inorganic substances this property has long been known, we need
only mention that at the temperature of solid carbon dioxide,
sulphur becomes almost colourless, red mercuric oxide becomes
yellow, and vermilion becomes scarlet, or, on heating, zinc oxide
becomes yellow, and that all these return to the original colour at
the ordinary temperature. This reversible change of colour in
solids depending on the temperature we propose to call tliermo-
tropy.

In the case of the Schiflf's bases, the change of colour with rise
of temperature is from yellow to orange to red, and on lowering of
temperature from red to orange to yellow, but in some cases at
the low temperature the colour disappears altogether. The elucida-
tion of this question, however, must await spectroscopic measure-
ments.

The extreme instability of the Schiff's bases, particularly those
derived from hydroxyaldehydes, their characteristic tendency to
form isomerides, is further illustrated by the differently coloured
modifications which can be obtained at will by varying the method
of their preparation or the temperature of crystallisation. (For
other instances of the changeability of Schiff's bases, see Anselmino,
Ber., 1905, 38, 3989; 1907, 40, 3465; also Manchot and Furlong,
Ber., 1909, 42, 3030.) In this connexion, allusion may also be
made to the changes which these bases undergo under the influence
of different solvents indicated by the different shades of colour that
they exhibit in solution.

Evidence is accumulating of reversible isomeric reactions, like
those described in this paper, which are indicated by physical
differences, such as changes of colour. It is possible that these
may be explained by hypotheses, similar to that of Hantzsch and
Werner, assuming intramolecular rearrangement; but in the case
of phototropy and thermotropy it should not be forgotten that
the substances exhibiting these phenomena are solids. No one
will doubt, however, that these differences of colour depend on
isomeric change of some kind; but in the case of solids we know
practically nothing of their molecules, not even of their relative
molecular weights. The molecules of solids are probably far more

PHOTOTROPY AND THERMOTROPV. PART T. 1945

complex than 1 liose of liquids or gases ; indeed, they may be rather
complex groiips or aggregates of ordinary gaseous molecules, which
would give rise to far more numerous possibilities of isomerism.
It appears to us that phototropic and thermotropic reactions are
more probably due to isomeric changes affecting the aggregation
of molecules in solids than to intramolecular change of molecules
derived from a study of gases.

The following compounds were obtained by the condensation of
the respective aldehydes and amines, in the usual manner; generally
in alcoholic solution, and without the application of heat.

Salicylidene-ra-toluidine, O'H.'C^^j^'Q'ii'.Cf^'H.^Q. — This photo-
tropic compound, which was described in a previous paper (loc. cit.),
is thermotropic, and also exhibits differences of colour in solution
in different solvents. No thermotropy could be observed at " the
higher temperature," just below its melting point, the latter being
so near the ordinary temperature, but at " the lower temperature,"
that of solid carbon dioxide, the yellow phototrojoc became paler in
colour and returned to the original colour at the ordinary tem-
perature. The darker phototrope was not altered appreciably in
colour by cooling. Solutions in ether, benzene, or light petroleum
are rather lighter in colour than those in chloroform, alcohol, or
glacial acetic acid.

Sdlicylidene-va.-tohiidine hydrochloride, Ci4H|30N,HCl, was
obtained as a yellow, amorphous precipitate by passing a current
of dry hydrogen chloride into a solution of the base in dry ether.
In presence of water, the salt hydrolyses readily. It is not photo-
tropic, but in presence of light and moist air it decomposes.
Thermotropy was detected at " the higher temperature " (150°) by
a darkening in colour, the original colour returning at the ordinary
temperature. There was no change of colour at ' the lower tem-
perature." It melts at 182° (corr.) :

0-2214 gave 0-1274 AgCl. HCl = 14-63.

Ci^Hi^ONCl requires HC1 = 14-72 per cent.

SalicyUdene-ra-toluidine picrate, Cj4Hj30N,C6H307N3. — Equi-
molecular proportions of salicylidene-m-toluidine and picric acid
were dissolved in hot alcohol and mixed. Small, bright yellow
needles separated immediately. This compound does not appear
to be phototropic or thermotropic. It melts at 179° (corr.) :

0-2130 gave 22-3 c.c. Ng (moist) at 13° and 772 mm. N = 12-57.
CaoHjeOgN^ requires N = 12-74 per cent.

o-M ethoxyb enzylidene-jn-toluidine, prepared by the interaction o\
o-methoxybenzaldehyde and w-toluidine, is a liquid, and was not
further examined.

Salicylidene-o-4-xylidene, OH'CgH^-CHIN'CeHgMea, is photo-

UU6 SENTER AND SHEPHEARO : STUDIES IN

tropic. It consists of light yellow needles, wliicli change to an
orange colour when exposed to sunlight, and resume their original
colour in the dark. At " the higher temperature " (70°), the
yellow phototrope exhibits thermotropy by darkening in colour and
returning to the original colour at the ordinary temperature; at
" the lower temperature," it becomes temporarily paler. The
darker phototrope showed no thermotropy except that when kept
for a short time at 70° it became paler in colour, and at the
ordinary temperature appeared to be identical with the yellow
phototrope. The base is soluble in the usual organic solvents, the
solutions in alcohol, chloroform, or acetic acid being darker in
colour than those in ether, benzene, or light petroleum. It melts
at 76° (corr.) :

0-2185 gave 12-2 c.c. Ng (moist) at 14° and 746 mm. N = 6-45.
Ci^HjjON requires N = 6-22 per cent.

o-Methoxyhenzylidene-oA-xylidine, OMe'C6ll4''CH!N"C6H3Me2,
was prepared by the interaction of o-methoxybenzaldehyde and
o-4-xylidine. No indication of phototropy or thermotropy could
be detected. It crystallises from alcohol in pale yellow prisms, and
is very soluble in the usual organic solvents ; the solution in glacial
acetic acid is yellow : in other solvents it is colourless, or only
pale yellow. It melts, forming a yellow liquid, at 45° (corr.) :

0-2751 gave 14-0 c.c. Ng (moist) at 18° and 769 mm. N = 5-95.
CjcHjyON requires N = 5-86 per cent.

Salicylidene-va.-^-xylidine and salicylidenemesidine were prepared,
but, proving to be liquids, were not further examined.

Salicylidene-o-cliloroaniline, OH'CcH4'CHIN"C(-H4Cl, separated
from the alcoholic solution as an oil, which on keeping solidified
to a mass of pale yellow crystals. It is phototropic ; when exposed
to sunlight it becomes orange, and the original colour returns in
the dark. Both phototropes exhibit thermotropy; at "the higher
temperature " the yellow jDhototrope darkens in colour, the original
colour returning at the ordinary temperature ; the orange photo-
trope at this temperature loses colour, and at the ordinary tem-
perature appears to be identical with the yellow phototrope. At
" the lower temperature," both yellow and orange isomerides
become much paler in colour. Salicylidene-o-chloroaniline dissolves
easily in the usual organic solvents; the solutions in alcohol,
chloroform, or glacial acetic acid are deeper in colour than those
in ether, benzene, or light petroleum. The base melts at 82 — 83°
(corr.) :

0-2436 gave 12-3 c.c. No (moist) at 14° and 769 mm. N:-600.
CjgHjoONCl requires N = 605 per cent.

PHOTOTROPY AND THERMOTROPY. PART I. 1947

0-M etJboxyh enzi/Iid (' It c-o-clil oroa nUin e , 0Me'C,,H.,'CH!N'Cr,H4Cl,
was prepared from o-methoxybenzaldehyde and o-chloroaniline in
alcoliolic solution, separating as a yellow oil, which soon solidified.
After crystallisation from light petroleum, it was obtained as pale
yellow prisms. Neither phototropy nor thermotropy was detected.
It is very easily soluble in benzene, chloroform, ether, or glacial
acetic acid, more sparingly so in alcohol or light petroleum. The
solutions are colourless, with the exception of that in glacial acetic
acid, which is yellow. The base melts at 69° (corr.) :

0-2378 gave ll'S c.c. No (moist) at 15° and 767 mm. N = 5-87.
Cj^HjgONCl requires N = 5"71 per cent.

SaJici/lidetie-va-c/doroaniline, OTl'Cf.'Hi'Cli'.lS! 'CqH ^C\, crystallises
from alcohol or light petroleum in orange-yellow leaflets. This base
is not phototropic, but exhibits thermotropy. At " the higher
temperature " the solid darkens, and at " the lower temperature "
becomes much paler; in either case it returns to the original shade
at the ordinary temperature. It dissolves readily in the usual
organic solvents, with the exception of light petroleum, in which
it is less soluble; the solutions in alcohol, chloroform, or glacial
acetic acid are deeper yellow than those in benzene, ether, or light
petroleum. The yellow alcoholic solution becomes much paler, and
the slightly yellow solution in light petroleum becomes colourless
at the temperature of solid carbon dioxide. Salicylidene-??^chloro-
aniline melts at 95° (corr.) :

0-2455 gave 12-6 c.c. No (moist) at 14° and 773 mm. N = 6-14.
CjsHkiONCI requires N = 6-05 per cent.

Salici/lide7ie-'p-chloroaniline, OII'C(;H4'CH!N'CgH4Cl, crystallises
from alcohol or benzene in brilliant yellow needles. It is not
phototropic. Thermotropy is indicated at " the higher tempera-
ture " by a distinct darkening in colour, and at " the lower tem-
perature " by the colour becoming much paler, in both cases
returning to the original shade at the ordinary temperature. It
dissolves in the usual organic solvents ; the solutions in benzene,
light petroleum, or ether are colourless, whilst those in alcohol,
chloroform, or acetic acid are yellow. At the temperature of solid
carbon dioxide, the colour of an alcoholic solution becomes dis-
tinctly paler. Salicylidene-p-chloroaniline melts at 102 — 103°
(corr.) :

0-2395 gave 12-3 c.c. No (moist) at 14° and 769 mm. N = 6-ll.
CjsHjoONCl requires N = 6-05 per cent.

Salicyliden e--m-amino'phennl , OH-CcH4'CH!N'C(;H4'OH, separates
in orange crystals on the addition of salicylaldehyde to a solution
of 7?i-aminophenol in dilute acetic acid. On dissolving in hot

IIUS SENIER AND SHEPHEARD : STUDIES IX

benzene, and adding an equal volume of light petroleum, reddisli-
orange scales of the base are obtained. This compound is not
phototropic, but exhibits thermotropy, the colour of the crystals
becoming darker at " the higher temperature " and much paler at
" the lower temperature," returning to the original colour in both
cases at the ordinary temperature. It is easily soluble in alcohol,
chloroform, or glacial acetic acid, forming deep yellow solutions ;
in ether, forming a pale yellow solution ; in benzene or light
petroleum, in both of which it is less soluble, the solutions are
colourless. The deep yellow alcoholic solution becomes much paler
at the temperature of solid carbon dioxide. Salicylidene-?7i-amino-
phenol melts at 128—129° (corr.) :

0-2653 gave 14-9 c.c. Ng (moist) at 15° and 766 mm. N = 6-63.
CjsHjjOgN requires N = 6'57 per cent.

Salicylidene-'p-ajninobenzoic acid, OH'CgH^.CHIN'C^H^'COoH,
crystallises from alcohol in bright yellow, silky needles. This
compound is phototropic. When exposed to the action of sunlight,
it darkens in colour, and returns to the original colour in the
dark or in subdued daylight. Both the light and the dark coloured
phototropes exhibit thermotropy. At " the higher temperature "
both isomerides darken in colour; on cooling to the ordinary tem-
perature, the paler phototrope resumes its original colour, and the
same colour is exhibited by the deeper coloured phototrope, which
apparently changes to the paler isomeride ; at " the lower tem-
perature " both phototropes become paler in colour. This base is
easily soluble in alcohol, chloroform, or glacial acetic acid, less so
in ether, benzene, or light petroleum. The solutions show about the
same tint of yellow ; the addition of water to the solution in glacial
acetic acid, or of hydrogen chloride to the solution in alcohol,
removes the colour, doubtless by hydrolysis. Salicylidene-jj-amino-
benzoic acid melts at 265 — 266° (corr.) :

0-2134 gave 10-5 c.c. Ng (moist) at 18-5° and 770 mm. N = 5-78.
C14HJ1O3N requires N = 5-81 per cent.

Sodium salicj/Iidene-p-aminobenzoate,

OH-CgH^-CHIN-CeH^-COaNa,
was prepared by dissolving p-aminobenzoic acid in hot alcohol,
exactly neutralising with sodium hydroxide solution, and adding
the calculated quantity of salicylaldehyde. Yellow prisms were
obtained, very much paler in colour than the free acid. This salt
is thermotropic, but not phototropic. At " the higher temperature "
it changes to red, and at " the lower temperature " becomes almost
colourless ; in each case returning to its original tint at the ordinary
temperature. It dissolves in cold water or alcohol, forming a
deep yellow solution, which hydrolyses on warming:

PHOTOTROPy AND THERMOTROPV. PART T. 194-0

0-7399 gave 01998 NaoSO^. Na = 8-7G.

Ci4Hi(,03NNa requires Na = 8'68 per cent.

Calciuin salicyiidene-ip-aminoh c?i zoate,

(OH-C6H4-CH:N-CcH4-C02)2Ca,
was obtained in pale yellow leaflets by the interaction of salicyl-
aldeliyde and an alcoholic solution of 2><iminobenzoic acid, which
was previously neutralised by calcium hydroxide solution. No
phototropy could be detected, but thermotropy was observed by a
darkening of colour at " the higher temperature." The salt
dissolves in cold water, and the solution hydrolyses on warming :

0-6690 gave 01683 CaS04. C = 7-41.

CosHooOgNoCa requires C = 7'71 per cent.

Bariii m solicylidene-'p-aminohenzoate,

(OH-CfiH4-CH:N-C,H4-COo)oBa,
consists of small, yellow needles, and exhibits similar jDroperties to
the calcium salt. It is thermotropic, but not phototropic. At
" the higher temperature " it becomes darker, and at " the lower
temperature " paler in colour, the original colour returning, in each
case, at the ordinary temperature.

For anal5'sis, the salt was dried at 100° :

0-5o51 gave 0-2110 BaSO^. Ba = 22-38.

C28H2o^6^2^^ requires Ba = 22-25 per cent.

o-Methoxyh enzi/lidene--p-aminohenzoic acid,

OMe-CcH^-CHIN-CeH^-COoH,
was prepared in alcoholic solution, using p-aminobenzoic acid and
o-methoxybenzaldehyde. It immediately separates in pale yellow
needles, which, recrystallised from benzene, become much paler in
colour. It is slightly thermotropic, but gives no indication of
phototropy. It dissolves in alcohol, ether, or glacial acetic acid,
and is sparingly soluble in benzene, chloroform, or light petroleum.
The solutions are colourless, with the exception of that in acetic
acid, which is yellow. The ether melts at 225-5° (corr.) :

0-2469 gave 12-2 c.c. Ng (moist) at 21° and 759 mm. N = 5-62.
C15II13O3N requires N = 5-49 per cent.

S alicyUd en e-a.-na'phthyl amine, OH'CgH^'CHtN'CjoHy. — In a pre-
vious paper {loc. cit.) we described this compound as consisting of
dark orange prisms which melt at 45-5°. We had overlooked an
earlier description by Pope and Fleming (Trans., 1908, 93, 1916),
who, however, obtained it in pale yellow needles melting at 53°.
This shows the influence of slight alterations of the experimental
conditions in determining the form of the product in the case of
compounds containing the group 'CHIN', which in so many

1950 SENIER AND SHEPHEARD : STUDIES IN

instances exhibit, different properties in the hands of different
observers (compare Hantzsch and Schwab, Bcr., 1901, 34, 828).
This compound is not acted on by light, but is thermotropic ; at
" the lower temperature " its dark orange colour changes to canary-
yellow, the former colour returning at the ordinary temperature.
Solutions of this base in ether, benzene, or light petroleum are
paler in colour than those in other solvents. The colour of the
alcoholic solution becomes temporarily paler at " the lower tem-
perature."

Salicylidene-^-na'phthylamine, ■OH'CcH4'CH!N'CioH7. — This
compound, previously prepared by Emmerich (Annalen, 1887, 241,
351), exhibits marked phototropic and thermotropic properties, its
colour showing reversible variations between yellow and orange or
red. We are at present submitting this compound to a more
detailed investigation. Emmerich gives the melting point of this
compound as 121°; the specimens we have prepared melt at 126°
(corr.).

Disalici/Iidene-p-phenT/lenediamine, (OH'C6H4*CHIN)2C6H4, may
be obtained either in pale yellow or orange-red plates. When the
aldehyde and the diamine are brought together in alcoholic solution
at a temperature below 50°, the mixture remains clear for a few
minutes, and then the compound quickly separates in' pale yellow
plates. If, however, the temperature of the experiment be above
50°, a mixture of both isomerides is formed, the proportion of the
red form increasing the higher the temperature employed, but
contact of solvents, in such a proportion that only a small part
dissolved with the yellow plates or the mixtures obtained, changes
the yellow into the more stable red isomeride. The change of the
yellow into the red form by this contact with solvents, accompanied,
of course, with partial solution, takes place in a few minutes when
the 'solvent is ethyl acetate, chloroform, benzene, or acetone; in
half an hour to an hour when alcohol or ether is used; whilst
with light petroleum several hours are requisite. It is noteworthy
that the order of solvents just given corresponds with that of the
solubility of the red isomeride; it is most soluble in the first group,
and least soluble in light petroleum.

No phototropy could be detected in either isomeride, but both
exhibit thermotropy, and, further, at 115° the yellow isomeride
changes to the red. When the yellow isomeride is heated, it
gradually deepens in colour, until, at about 110°, it becomes
orange. If the temperature is then lowered, the reverse changes
of colour take place; if, however, the temperature is allowed to
rise above 110°, the orange colour changes gradually into red and
deep red until the melting point is reached. On lowering the

PHOTOTROPY AND THERMOTROPY, PART I, 1951

temperature, the reverse changes of colour are observed until a
temperature of about 115° is reached; below this temperature, the
orange and yellow colour does not reappear, but the red merely
becomes slightly paler. This isomeric change at 115°, not being
reversible, is not phototropic, although it takes place under the
thermotropic conditions pertaining to that temperature. At the
temperature of solid carbon dioxide, the yellow isomeride gave no
indication of thermotropy, but the red isomeride became yellow,
returning to red at the ordinary temperature. The red isomeride
melts at 212—213° (corr.) :

0-2192 gave 16-7 c.c. Ng (moist) at 17° and 769 mm. N = 8-94.
CooHjgOoNo requires N = 8'86 per cent.

2 : 2' -DimethoxT/dih enzi/lidene-Yi-'phenylenediamine,
(OMe-CcH,-CH:N)2CcH4,
was prepared by the interaction of the diamine and o-methoxy-
benzaldehyde in alcoholic solution. After rocrystallisation from
alcohol, pale yellow needles of the ether were obtained. It is not
phototropic, and but slightly thermotropic. It dissolves readily
in most organic solvents, sparingly in ether. In glacial acetic acid,
the solution is dark red. The hydrochloride, which was prepared
by passing hydrogen chloride into an ethereal or chloroformic solu-
tion of the base, is red, in the first instance, but soon changes to
orange-yellow. The base melts at 152° (corr.) :

0-2492 gave 17-7 c.c. No (moist) at 17° and 766 mm. N = 8-31.
C22H20O0N2 requires N = 8-14 per cent.

m-Hydroxyhenzylidene-in.-toluidine, OH'CgH4*CH!N*CgH4Me, was
obtained in colourless crystals on the addition of the amine to the
aldehyde solution. The crystals were dissolved in warm benzene,
and light petroleum added, when long, colourless prisms of the base
slowly separated. This compound is neither phototropic nor thermo-
tropic. It dissolves readily in the usual oiganic solvents, but is
sparingly soluble in light petroleum. With the exception of the
solution in glacial acetic acid, which is yellow, the solutions are
coloixrless. The hydrochloride is yellow. 7?i-Hydroxybenzylidene-
m-toluidine melts at 106 — 107° (corr.) :

0-2592 gave 14-6 c.c. N2 (moist) at 16-5° and 765 mm. N = 6-60.
Cj^HjoON requires N = 6-64 per cent.

•p-Hydroxyhenzylidene-m.-toliiidine, OH'CgH^'CHiN'CcH^Me. —
m-Toluidine was added to a solution of j^-hydroxybenzaldehyde in
hot benzene. Small, colourless crystals separated on cooling, which,
dried in the air, became slightly yellow. When recrystallised from
alcohol, pale yellow plates were obtained, whilst from benzene almost
colourless crystals were obtained, the latter not very well defined.

19o2 SENTER AND SHEPHEARD : STUDIES IN

Both the pale yellow crystals from alcohol and the almost colourless
crystals from benzene, when rubbed in a mortar, became distinctly
yellow. Whether these different colours represent or not distinct
isomerides or isomeric mixtures was not determined.

This compound is not phototropic, but exhibits thermotropy. At
" the higher temperature " the pale yellow crystals from alcohol deepen
in colour, the original colour returning at the ordinary temperature ;
the colourless crystals from benzena do not change. At " the lower
temperature " the yellow crystals become colourless, their colour
returning at the ordinary temperature.

Both sets of crystals behave similarly towards solvents. The
compound dissolves readily in alcohol, ether, glacial acetic acid, or
ethyl acetate ; less readily in chloroform or benzene ; sparingly in
light petroleum. The solutions are yellow except those in ether
or benzene, which are almost colourless.

23-Hydroxybenzylidene-??2-toiuidine melts at 181° (corr.) :

0-2663 gave 15-0 c.c. No (moist) at 18° and 763 mm. N = 6-53.
Ci4H]30N requires N = 6'64 per cent.

Anisjjlidene-m.-tohiidine, OMe'CgH^'CHIN-CgH^Me, was prepared
from anisaldehyde and ??i-toluidine. It crystallises from alcohol in
small, colourless plates soluble in the usual organic solvents ; in
glacial acetic acid the solution is yellow ; the other solvents give
colourless solutions. It melts at 59° (corr.) :

0-2922 gave 15-95 c.c. No (moist) at 14-5° and 750 mm. N = 6-32.
CijHjjON requires N = 6-22 per cent.

AnisyUdene-m-toluidine hydrochloride, CjgH^jONjHCl. — A solu-
tion of the base in dry ether was saturated with dry hydrogen
chloride, when the salt was precipitated as a pale yellow powder.
It melts at 174° (corr.). When dissolved in alcohol and neutralised
with a standard solution of sodium hydroxide, using phenol-
phthalein as indicator :

0-7553 required 27-4 c.c. (1 c.c. = 0-003854 HCl). HC1 = 14-04.
CisHigONCl requires HCl = 13-93 per cent.

2-Hydroxy-b-methylbenzylidene-xa'toluidine,

OH-CeHgMe-CHIN-CcH^Me,

crystallises from alcohol in pale orange leaflets, very soluble in the
usual organic solvents. It is not phototropic, but exhibits thermo-
tropy; at "the higher temperature" it darkens in colour, and at
" the lower temperature " it becomes paler, and returns to the
original colour, in both cases, at the ordinary temperature.

In benzene, light petroleum, or ether, the solutions of this base

PHOTOTROPY AND THERMOTROPY. PART I. 1953

are faintly yellow, while those in acetic acid, alcohol, or chloroform
are deep yellow; at " the lower temperature " the alcoholic solution
exhibits thermotropy similar to the solid.

2-Hydroxy-5-methylbenzylidene-m-toluidine melts at 70° (corr.) :
0-2672 gave 140 c.c. N^ (moist) at 14° and 767 mm. N = 6-23.
Cj-jHijON requires N = 6-22 per cent.

2 : 2'-Dihydroxy-b : b'-dimethylclihenzylide7ie--g-'phenyltnediamine,
(OH-C6H3Me'CH:N)2C6H4,
occurs apparently iu two isomeric modifications; the one, crystal-
lised from benzene, in bright yellow leaflets, which melt at 256°
(corr.) ; the other, in yellowish-brown crystals, crystallised from
glacial acetic acid, which melt about half a degree lower than the
preceding isomeridc. No indication of phototropy was observed,
but both isomerides exhibit thermotropy at the " higher " and
" lower temperatures." Both behave in the same manner towards
solvents; in benzene, chloroform, or glacial acetic acid, they are
sparingl}' soluble, and less soluble in alcohol or light petroleum :

0-2822 gave 20-1 c.c. No (moist) at 18° and 760 mm. N = 8-23.
C22H00O0N2 requires N = 8-14 per cent.

5-Bro77iosalicylidene-m.-toluidi7ie, OH'CgHgBr'CHIN'CyH^Me,

crystallises from alcohol in yellow plates mixed with slightly darker
coloured prisms of a possible isomeride. No phototropy was
detected, but thermotropy was observed at both " the higher " and
" the lower temperatures." It dissolves easily in the usual organic
solvents, the solutions in ether, benzene, or light petroleum being
paler in colour than those in chloroform, alcohol, or glacial acetic
acid. The base melts at 102—103° (corr.) :

0-3262 gave 13-5 c.c. N. (moist) at 15° and 757 mm. N = 4-83.
Ci^HjoONBr requires N = 4-83 per cent.

5 : d'-Dibromodisalicylidene-'p-phenylenediamine,
(OH-C6H3Br-CH:N)2C6H4.
■ — ^This compound, after recrystallisation fi'om nitrobenzene, was
obtained in dark yellow leaflets almost insoluble in solvents of low
boiling point. It is not phototropic, but exhibits thermotropy. At
"the higher temjoerature '' it is distinctly red, and at "the lower
temperature " loses much of its yellow, in both cases returning to
its original colour at the ordinary temperature. It melts at 306°
(corr.) :

0-2408 gave 12*2 c.c. No (moist) at 18° and 767 mm. N=:5-91.
C2oHi402N.2Br2 requires N — 5-91 per cent.

3-yitrosalicylidene-m.-toluidine, OH'C6H3(N09)*CHIN*C(;H4Me,
was obtained from solution in alcohol in light red needles. It is

1054 PHOTOTROPY AND THERMOTROPY. PART I.

not phototropic, but exhibits thermotropy at both " the higher "
and especially " the lower temperature." Tt dissolves readily in
benzene, chloroform, or acetic acid, and is not so soluble in alcohol,
ether, or light petroleum. The colour of the solutions is the same,
but the solution in chloroform shows green fluorescence. Low
temperature thermotropy was observed in the case of the alcoholic
solution. It melts at 144 — 145° (corr.) :

0-2309 gave 21-5 c.c. No (moist) at 14° and 759 mm. N=^ 10-95.
C14H10O3N2 requires N = 10-94 per cent.

5-yitrosaIici/lidene-m-toluidine, 011'CQR2(N02)'C'Bi'.'N-CQR^Me,
crystallises from alcohol in bright yellow needles. It is not affected
by light, but exhibits thermotropy at both " the higher " and " the
lower temperature." The behaviour towards solvents, including the
fluorescence of the chloroformic solution, and the thermotropy ot
the alcoholic solution, is similar to that of the isomeride just
described. It melts at 139° (corr.) :

0-2113 gave 19-7 c.c. No (moist) at 15° and 759 mm. N = 10-91.
C14H12O3N2 requires N = 10-94 jDer cent.

Vanillidene-m.-toluidine, OH'CgH3(OMe)'CH!N'CgH4Me, crystal-
lises from light petroleum in colourless, silky needles. It is not
affected by light nor by temperatures below its melting point. It
dissolves in the usual organic solvents ; the solution in alcohol or
acetic acid is deep yellow, in chloroform it is pale yellow, and in
ether, benzene, or light petroleum, colourless. If the crystals arc
rubbed in a mortar, they become temjoorarily yellow. It melts at
96° (corr.), forming a yellow liquid :

0-2574 gave 13-2 c.c. No (moist) at 16-5° and 751 mm. N- 5-90.
CjjHjyOoN requires N — 5-81 per cent.

Piperoni/lidene-m.-toluidme, CHoI02*CcH3'CH!N*C6H4Me, crystal-
lises from alcohol in small, colourless prisms. It is easily soluble
in the usual organic solvents, giving colourless solutions, except the
solution in glacial acetic acid, which is yellow. It melts at 71°
(corr.) :

0-2964 gave 14-9 c.c. Ng (moist) at 16° and 768 mm. N = 5-91.
CJ5HJ3O2N requires N = 5-86 per cent.

2-Uydroxy-a-na'phthylident-m.-toluidine, OH*C](,Hc*CH!N'C6H4Me,
crystallises from alcoholic solution in orange-yellow needles. It is
not affected by light, but shows thermo'ropy at both the " higher "
and the "lower temperatures;" it dissolves in the usual organic
solvents, exhibiting no differences of colour. It melts at 91-5°
(corr.) :

0-2376 gave 10-6 c.c. N2 (moist) at 14° and 748 mm. N-5-17.
CjgHjjON requires N = 5-37 per cent.

CONDENSATION OF KETONES AND ALDEHYDES, ETC, 1955

2-lIydroxij-a-na'pJithylidtne-fi-na'phthylamine,
OH-CmH,;CH:N-C,oH7,
which has beeu previously described (Bartsch, Ber., 1903, 36, 1975),
crystallises from alcohol in dark orange needles. It is not photo-
tropic, but exhibits thermotropy at both " the higher " and " the
lower temperatures." Its solutions show no difference of colour.
Its hydrochloride is orange. We find, in agreement with Bartsch,
that the base melts at 143° (corr.) :

0-2242 gave 9-2 c.c. Ng (moist) at 17-5° and 755 mm. N = 4-74.
CgiHjjON requires N = 4'72 per cent.

2 : 'I'-Dihydroay-di-a-najjhthylidene-'^-'phenylen ediamine,

(oh-CioH6-ch:n)2C6H4.

— This compound consists of small, glistening, crimson-red crystals.
It is sparingly soluble in organic solvents. It is not affected by
light, but exhibits thermotropy both at " the higher " and " the
lower temperatures." It melts at 307° (corr.) :

0-2226 gave 13-1 c.c. Ng (moist) at 18° and 760 mm. N = 6-80.
C28H20O2N2 requires N = 6-73 per cent.

Cinnamylidene-m-toluidine, CeHg'CHlCH'CHiN'CcH^Me, crystal-
lises from alcohol in dark yellow prisms. It is neither phototropic
nor thermotropic. It dissolves in the usual organic solvents, the
solutions being yellow, except that in glacial acetic acid, which is
red. It forms a deep yellow hydrochloride. The base melts at
124° (corr.):

0-2630 gave 14-4 c.c. No (moist) at 17-5° and 759 mm. N = 6-33.
CigHjjN requires N = 6'33 per cent.

University College,
Galwat.

CCXV. — The Condensation of Ketones and Aldehydes
■with the Sodium Derivative of Ethyl Cyanoacetate.
Part 11.

By Henry Dent Gardnee, jun., and Walter Norman Haworth.

In a previous communicition by one of us (Haworth, this vol., 480),
the condensation of cyclic ketones with ethyl sodiocyanoacetate, first
studied by Harding, Haworth, and Perkin (Trans., 1908, 93, 1944),
was extended to the more general cases of aldehydes and ketones, such
as phenylacetaldehyde and acetophenone, in order to discover in

1956 GARDNER AND HA WORTH : THE CONDENSATION OF

what direction this condensation might be useful for further synthetic
work. The results which were obtained at that time seemed to make
it desirable that simpler cases should be investigated, and the present
communication is the outcome of experiments in this direction.

Komppa [Ber., 1900, 33, 3530) has studied the condensation of
acetone with ethyl cyanoacetate, using a trace of piperidine as the
condensing agent, and by a process which extended over many weeks
he succeeded in isolating two definite products.

The reaction proceeded in two stages :

COMe. + CN-CHa'COgEt = CMe2:C(CN)-C0.,Et + H2O.
CMe,,:C(CN)-C02Et + CN-CHVcOgEt =

" c6lEfCH(CN)-CMe2-CH(CN)-C02Et.

We have discovered that the condensation proceeds in quite
an unexpected direction if sodium ethoxide is employed in the place of
piperidine. When acetone is condensed with ethyl sodiocyanoacetate,
the reaction is of a complicated character, the final product being ethyl
2 : ^-dicyano-\ : 1 : D-triinethyl-A' *-cyc\ohexadie>i-3'ol - Q-carboxylate,

.ue<=^^jj C(OH)^^ ^^^•

This substance, which melts at 135°, gives a green coloration in
alcoholic solution with ferric chloride, and dissolves readily in sodium
carbonate, the increased acidity being probably due to the close
proximity of the cyano- to the hydroxy-group.

The course of the reaction may be expressed by assuming that the
first product is ethyl aa'-dicyano-/3^-dimethylglutarate, which was
obtained as stated above by Komppa. The presence of sodium
ethoxide in our experiments had the effect of inducing a secondary
condensation with an extra molecule of acetone to take place :

OMe.<gi(gN);CO.CH,COMe ^,,,^.

The latter substance contains four reactive hydrogen atoms, and in
contact with hydrochloi-ic acid undergoes tautomeric change, with the
elimination of water and the formation of a six-membered ring :

CMe <C(CN)===C(OHK .

CMe <C(CN)=:=C(OHK

Striking confirmation of this view of the mechanism of the reaction
was obtained from the condensation of ethyl cyanoacetate with methyl
ethyl ketone. In this case the substitution of an ethyl group for one
of the methyl groups in acetone, modified the result to some extent by

KETONES AND ALDEHYDES, ETC. 1957

introducing the factor of steric hindrance, which was responsible for
the loss of a carbethoxy-group in the form of ethyl carbonate. As
before, the initial stage is evidently the formation of ethyl aa'-dicyano-
;3-methyl-^-ethylglutarate, which then reacts with another molecule
of the ketone, hydrolysis taking place under the influence of sodium
ethoxide :

CMeEt<CgN)(CO,H).CMe:CHMo_

This open-chain compound subsequently condenses to a six-membered
ring with formation of an imino-group :

CMeEt<C(CN)(C03H)-ClIe>Cjj^ _^

CMeEt<C<C^K£2i'c\>:S'^;>CMe

It is important to observe that this is another instance of the
production of an alicyclic compound by the formation of the imino-
grouping, which in the case of a five-membered ring has been so
elegantly worked out by Dr. J. F. Thorpe (this vol., 685). We are
indebted to his researches on the imino-compounds for the elucidation
of the constitution of this and other compounds met with in this
investigation.

The above imino-compound, Q-imino-3-cyano-l : 2 : i:-trimethylA-ethyl-
^^-cycloheocene-o-carboxylic acid, is yellow and melts at 108°. It
dissolves readily in cold concentrated hydrochloric acid, and on
digestion is converted into o-ci/ano-l :2:4:-tri7nethi/l-i-ethi/l-A^'-^-cyclo-
hexadien-6-ol-2-carbox7/lic acid,

CMeEt<gg£)i£M).;^M;>OMe,

which is a liquid boiling at 193°/18 mm.

By a slight variation of the conditions, a simpler condensation
product was subsequently obtained, namely, a-ci/ano-/3-methyl-(3-ethyl-
acrylic acid, which on distillation is decomposed with elimination of
carbon dioxide and formation of fi -methyl- ji-ethylacrylonitrile :
CMeEt:C(CN)-COoH -^ CMeEt:CH-CN.

When this nitrile is hydrolysed under the conditions described in
the experimental part of this paper (p. 1962), it yields /3-methyl-^-
ethylacrylic acid.

The constitution of the acid was controlled by oxidation with
permanganate, when methyl ethyl ketone was recovered from the
products and identified by its boiling point and the behaviour of its
semicarbazone.

VOL. XCV. 6 N

1958 GARDNER AND HAWORTH : THE CONDENSATION OF

From a similar condensation of diethyl ketone with ethyl cyano-
acetate, a-cyano-^-dietki/lacrylic acid was isolated, and this readily
passes with loss of carbon dioxide into the corresponding ^-diethyl-
acrylonitrile :

CEt,:C(CN)-CO.,H — > CEtglCH-CN.

The condensation has also been carried out with other homologues
of acetone, namely, methyl propyl ketone and methyl hexyl ketone,
with results which are exactly analogous to those described above ;
these are given in detail in the experimental part of this paper.

Experimental.
Ethyl 2 : 6-Dicyano-l: 1 : 5-trimethyl-^^'^-cyc\ohexadien-3-ol-Q-

A good yield of this acid was obtained under the following
conditions : Sodium (4 '6 grams), dissolved in ethyl alcohol, was
mixed with ethyl cyanoacetate (22-6 grams), and, after the separation
of the white sodium derivative, acetone (11 grams) was added to the
mixtui-e. The white sodium derivative immediately dissolved,
forming a clear yellow solution, which, on heating for an hour on the
water-bath, deposited a yellow sodium salt. The product was cooled,
dissolved in water, acidified with hydrochloric acid, and extracted
with ether. The extract was washed several times with water,
and afterwards with [sodium carbonate, which dissolved the chief
product of the reaction. This alkaline solution was acidified with
excess of mineral acid, when an oil was deposited which, on keeping
overnight, crystallised to a hard cake.

In another experiment, this oil was extracted with ether, and, after
evaporation, was left to solidify in an open basin, but crystallisation
did not take place even after the introduction of a crystal of
the solid substance ; it could only be induced to solidify by leaving
it in contact with hydrochloric acid for several hours. The agency
of hydrochloric acid is therefore necessary to complete the last stage
of the synthesis. The substance was recrystallised from a mixture
of benzene and light petroleum, or, better, from dilute methyl alcohol,
from which it separates in colourless needles melting at 135°.

Owiog probably to the strongly negative chax-acter of the hydroxy-
group due to the proximity of a cyano-group, the compound dissolves
readily in cold sodium carbonate, forming a deep yellow solution,
which also decolorises permanganate instantly. It is readily soluble
in benzene or alcohol, and in solution of the latter solvent it gives
a deep green coloration with ferric chloride. It is sparingly soluble
in water or light petroleum :

KETONES AND ALDEHYDES, ETC. 1959

0-1220 gave 0-2880 CO., and 0-0680 H^O. 0 = 64-4 ; H-6-2.

0-1333 „ 13-6 c.c. N2 at 18° and 755 ram. N=ll-6.

Ci^H^fiOsNg requires C = 64-6 ; H = 6-1 ; N = 10-8 per cent.

The benzoyl derivative crystallises from methyl alcohol in colourless
needles, melting at 116°, and containing one molecule of water
of crystallisation. This derivative dissolves in the ordinary organic
solvents, but is insoluble in cold alkali, and gives no coloration with
ferric chloride :

01123 gave 0-2700 CO2 and 0-0600 HgO. 0 = 656; H = 5-9.

0-1080 „ 7-0 c.c. No at 18° and 752 mm. N = 7-4.
a,iH„oO^N2,H20 requires C = 660 ; H = 5-8 ; N - 7-3 per cent.

6-/7mwo-3-cyano-l : 2 : 4- trimethyl-ii-ethyl-^^-cyc\ohexene- 3-carboxylic
Add, CMeEt<C™WCM»>CMe.

In preparing the above acid, sodium (11-5 grams), dissolved in
absolute ethyl alcohol, was mixed with ethyl cyanoacetate
(56-5 grams), and as soon as the white sodium compound had
separated, methyl ethyl ketone (36 grams) was introduced into
the very hot mixture, which was then heated for two hours on
the water-bath. The white sodium compound first dissolved, forming
a clear yellow solution, from which a bulky, yellow pi-ecipitate
gradually separated. After cooling, the product was dissolved in
water, acidified with very dilute hydrochloric acid, and extracted
with ether. The ethereal solution was washed until free from
alcohol and shaken with dilute sodium carbouate solution ; the
slight residue remaining in the ether consisted of unchanged ketone
and ethyl carbonate along with some neutral oils, the investigation
of which is not yet complete. The .sodium carbonate extract was
acidified with dilute hydrochloric acid, the solution during the process
being kept in violent agitation, until the oil suddenly became solid.
This was immediitely collected, well washed, and spread on porous
porcelain, and, when quite dry, recrystallised from benzene, from
which solvent it separated in light yellow needles, melting and
decomposing at 108° :

0-1411 gave 0-3444 CO2 and 0-0991 H2O. C = 66-5; H = 7-8.

0-1516 „ 16-6 c.c. ^2 at 12° and 762 mm. N = 130.

C13H1SO2N2 requires C = 66-6 ; H = 7-7 ; N = 12-0 per cent.

A titration with iA710-sodium hydroxide gave the following
results :

0-2698 required 0-0454 NaOH, whereas the same weight of a
monobasic acid, Cj3Hjs02N2, requires 0-0461 NaOH.

1960 GARDNER AND HAWORTH : THE CONDENSATION OF

6-I>ni)io-3-cyano-l : 2 : Ai-trimethyl-^-ethyl-£i}-cyc\ohexene-Z-carhoxylic
acid is soluble in benzene or alcohol, but sparingly so in light
petroleum ; it decomposes slowly in contact with the air. Its
solution in alcohol becomes deep brown on the addition of ferric
chloride. It also dissolves at once in concentrated hydrochloric acid,
which effects the hydrolysis of the imino-group.

3-Ci/ano-l : 2 : i-trimefJif/l-i-ethyl-A^'^-cyclohexadieoi-Q-ol,

The imino-compound just described was dissolved in cold con-
centrated hydrochloric acid, and, after twelve hours, the solution was
diluted by adding twice its volume of water and digested for two
hours in a reflux apparatus ; carbon dioxide was evolved and an oily
layer appeared on the top of the liquid. This was extracted with
ether, evaporated, and distilled under diminished pressure, when
almost the whole passed over at 193 — 194°/18 mm. as a colourless
oil. The product was now insoluble in cold sodium carbonate,
although it dissolved slightly on boiling ; the oil dissolved at once in
potassium hydroxide when sufficiently dilute, forming a yellow
solution, but the potassium salt is only sparingly soluble in
concentrated alkali :

0-1002 gave 0-2780 COo and 0-0782 H2O. C = 75-6 ; H = 8-7.

0-1136 „ 7-5 c.c. N2"at 18° and 758" mm. N = 7-6.

CiaHjyON requires 0 = 75-4: ; H = 8-9 ; N = 7-3 per cent.

The substance is an oil with an odour resembling that of a nitrile ;
its solution in alcohol gives a dark red coloration with ferric chloride.
It readily forms a benzoyl derivative, but as this showed no signs of
crystallising it was distilled under diminished pressure, when it boiled
constantly at about 250°/40 mm., and gave the following numbers on
analysis :

0-1177 gave 0-3307 COg and 0-0749 H2O. 0 = 767; H = 7-l.
Cj.^HaiOgN requires C = 77-3 ; H = 7-l per cent.

The benzoyl derivative is insoluble in alkalis, and does not give a
coloration with ferric chloride.

The carbonate of the hydroxy-acid was also prepared by leading a
stream of carbonyl chloride into an aqueous solution of the potassium
salt. An oil was precipitated, which was extracted with ether, and, as
it did not solidify, was distilled under 25 mm. pressure, when it
passed over at 260'' as a viscid, colourless liquid :

0-1203 gave 0-3228 COg and 0-0866 HjO. C = 73-2 ; H = 8-0.
C 5H32O3N2 requires C = 735 ; H = 7*8 per cent.

KETONES AND ALDEHYDES, ETC. 11)61

(i- Methyl- P-ethylacrylonitrile, CMeEtlCH'CN.

By a modification of the method employed in the condensation of
equimolecular quantities of methyl ethyl ketone and ethyl sodiocyano-
acetate described above (p. 1959), an oily mixture was obtained which
could not be crystallised ; it is explained below that this was due to
the course of the initial reaction having proceeded in a rather different
direction. In the former preparation care was taken to bring
together the reacting substances in such a way as to produce as
vigorous a reaction as possible at the beginning ; but if on the other
hand the reagents are allowed to cool before mixing, and the initial
stage of the condensation is thus rendered less violent, the oil which
is precipitated from the sodium carbonate solution by mineral acid does
not crystallise.

Subsequent investigation showed that the course which the
reaction follows under these conditions is :

COMeEt + CN-CHNa-COgEt -^ CxMeEt:C(CN)-C02H,
whilst at the same time a small quantity of 6-imino-3-cyano-l : 2 : 4-
trimethyl-4-ethyl-A^-c?/c^ohexene-3-carboxylic acid (p. 1959) is also
formed. This was demonstrated by submitting the oily mixture of
acids to fractional distillation under diminished pressure ; the process
is accompanied by the elimination of carbon dioxide and the formation
of an oil possessing the disagreeable odour of a nitrile, which passed
over at 95 — 105°/ 100 mm. in the first instance. A further small
fraction was collected at 180°/ 150 mm. The lower boiling fraction
consisted of ^-methyl-y3-ethylacrylouitrile, which was further purified
by repeated distillation, and then analysed :

0-1308 gave 17-1 c.c. Ng at 16° and 743 mm. N= 14-9.
CfiHgN requires N= 14*7 per cent.

fi- Methyl- ^-ethylacrrjlonitrile is a colourless, mobile liquid, which
distils at lOr/100 mm.

The higher boiling fraction gradually solidified, and, after draining
on porous porcelain, was recrystallised from benzene, from which
solvent it separates in long needles melting at 184°. The investigation
of this substance is not yet complete ; it seems to possess a high
molecular weight and a rather complex constitution :

0-1789 gave 0-4647 CO2 and 00929 HgO. C = 70-8; H = 5-8.

0-1211 „ 16-6 c.c. K, at 16° and 756 mm. N-15-9.

After the fractionation a considerable residue remained behind in
the flask, which was found to have crystallised ; this on purification
melted at 108°, and was identified as the iminocarboxylic acid of this
melting point.

1962 GARDNER AND HAWORTH : THE CONDENSATION OF

P-MeiJi7jl-P-ethylacrylic Acid, CMeEtlCH-COaH.

The hydrolysis of ;8-methyl-/3-ethylacrylonitrile is best carried out
by digesting it for twenty-four hours with 20 per cent, alcoholic
sxilphuric acid, when, on cooling, crystals of ammonium sulphate
separate out. The product was poured into water, extracted with
ether, the ethereal solution well washed with water, and then
evaporated. The residual oil was digested for a few minutes with
methyl-alcoholic potash, then poured into water, and the neutral
portion extracted with ether. The aqueous solution was acidified,
when an oil separated, which was dissolved in ether, and the ethereal
solution was dried and evaporated ; the residue distilled at 208° under
the ordinary pressure :

0-1143 gave 0-2640 COg and 0-0900 HgO. C = 63-0; H = 8-8.
C^^H^fjOg requires C = 63-2 ; H = 8-8 per cent.

A titration with iV/10-sodium hydroxide gave the following result :
02042 required 0-0720 NaOH, whereas the same weight of a monobasic
acid, C<,H^o02, requires 0-0717 NaOH,

(i-Methyl-^-ethylacrylic acid is a colourless, mobile liquid, possessing
an odour characteristic of olefinic acids ; it is sparingly soluble in
water, and a solution of its sodium salt instantly decolorise
permanganate.

The anilide is a colourless substance melting at 93 — 94° :

0-0800 gave 5-4 c.c. Ng at 20° and 752 mm. N = 76.
CjgHjsON requires N = 7-4 per cent.

Oxidation. — About 5 grams of the acid were dissolved in excess
of dilute sodium carbonate in presence of powdered ice, and a 1 per
cent, solution of potassium permanganate was slowly added. As soon
as the oxidation was complete, the product was subjected to steam
distillation, when an oil having the odour of a ketone passed over
and was salted out from the distillate and extracted with ether.
After removal of the ether, an oil, boiling at about 80°, remained,
which was easily identified as methyl ethyl ketone by its general
properties and by the melting point of its semicarbazone.

5-Imino-2-cyano-\ : 3-dimethyl-C)-ethyl-3-propy/-A'''-cyc\ohexene-
2-carboxylic Acid, CMePr<^^^^li^^l'^l^^>CEt.

A hot solution of sodium (5-7 grams) in alcohol was treated with
ethyl cyanoacetate (28 grams), and, after the separation of ethyl sodio-
cyanoacetate, methyl propyl ketone (21*5 grams) was quickly added to
the hot mixture. The reaction proceeded as before, and the product
was worked up as described in the previous cases. The amount of

KETONES AND ALDEHYDES, ETC.. 1963

neutral oil formed was too small to investigate; the acid separated
from the sodium carbonate extract as an oil, which, on stirring, soon
solidified. It was collected^ washed, drained on a porous tile, and then
recrystallised from benzene, in which solvent it is almost insoluble in
the cold ; it separates in glistening leaQets, melting and decomposing
at 113—114°:

0-1672 gave 0-4226 CO2 and 0-1290 HjO. C = 68-9; H = 8-6.

0-1504 „ 13-7 c.c. N2 at 13° and 746 mm. N = 10-6.

^15^.2202^:2 requires 0 = 68-7 ; H = 8-4; N=10 7 percent.

A titration with ^/10-sodium hydroxide gave the foUovsring results :
0-3160 required 00479 NaOH, whereas the same weight of a mono-
basic acid, Cj-,H.3202^2> requires 0-0482 NaOH.

The imino-acid decompo.ses slowly on expo.sure to the air ; it is readily
soluble in alcohol or hot benzene, but only sparingly so in light
petroleum. Concentrated hydrochloric acid dissolves it at once, effect-
ing the hydrolysis of the imino-group and the production of the
corresponding liydroxy-acid. The addition of ferric chloi-ide to a little
of the acid dissolved in alcohol causes the precipitation of a lirown
substance.

fi- Methyl- (i-2^'opylacrylonitrile, CMePrI CH* CN.

By moderating the conditions of the experiment described above, so
as to produce a less energetic reaction, an oily mixture of acids, similar
in constitution to that obtained under parallel conditions in the case
of methyl ethyl ketone (p. 1961), was precipitated from the sodium
carbonate solution. The oil was dissolved in ether as before, and the
oily residue, after evaporation, was slowly distilled under diminished
pressure, when almost the whole passed over between 90° and 100°/
30 mm. The initial product of the condensation is doubtless a-cyano-
/3-methyl-/8-propylacrylic acid, which readily passes on distillation into
li-methyl-fi-propylacrylonitrile. This is a light, colourless oil, possessing
the pungent odour characteristic of nitriles, and boiling at 95 — 96°/
30 mm. :

0-1530 gave 17-4 c.c. Xg at 12° and 748 mm. N = 13-2.
C7H11N requires N = 12-8 per cent.

P- Methyl- (i-propylacrylic Acid, CMePrlCH'COgH.

The nitrile just described was readily hydrolysed by digesting it for
eighteen hours with 20 per cent, alcoholic sulphuric acid, and subse-
quently treating the ester thus formed with methyl-alcoholic potash
(see p. 1962). On acidifying the solution of the potassium salt, an
oil was obtained which distilled at 222 — 225° under ordinary pressure.
This acid is a mobile, colourless liquid, having the odour of fatty acid

1964 GARDNER AND HAWORTH : THE CONDENSATION OF

a solution of its sodium salt decolorised permanganate instantly ; it
also combines freely with bromine in a chloroform solution :
0-1265 gave 0-3019 CO., and 01058 HgO. 0 = 65-1 ; H = 9-3.
0711^2^2 re<l"ii"es C = 65-6 ; H = 9-4 per cent.

ji- Methyl- (S-liexylacrylonitrile and fi-M ethyl- ^-hexylacrylic Acid,
CfiHig-CMelCH-COoH.

Sodium (4-6 grams), dissolved in alcohol, was mixed with ethyl
cyanoacetate (22-6 grams), and to the hot solution methyl hexyl ketone
(26 grams) was added, and the product worked up as described in
previous cases (p. 1959). In this example, no solid acid was isolated in
the first instance, so that the oil was subjected to fractional distillation
under 100 mm. pressure, when carbon dioxide was eliminated, and a
large fraction of oil was collected at about 130°. A considerable residue
remained behind in the flask, and a portion of this afterwards solidified
(see below). The distillate was further purified, and, on analysis,
gave numbers agreeing with the formula of ^-methyl- fi-hexylcicrylo-
nitrile :

0-1220 gave 9-8 c.c. N2 at 15° and 762 mm. N = 9-4.
CjqH^5,N requires N = 9-3 per cent.

This nitrile was digested for eighteen hours with 20 per cent,
alcoholic sulphuric acid, and the resulting ester treated with methyl-
alcoholic potash. On acidifying the alkaline solution after adding
water, an oily acid was obtained which distilled constantly at
158°/20 mm. fi- Methyl -/S-hexylacrylic acid is a colourless oil, possessing
an olefinic odour, and when dissolved in sodium carbonate it
decolorises permanganate at once :

0-1560 gave 0-4030 COg and 0-1502 H2O. C = 70-4 ; H = 10-7.
CjoH^gOg requires C = 70*6 ; H = 10-6 per cent.

To determine its basicity, the acid was titrated with iV/lO-sodium
hydroxide : 0-1860 required 0-0431 NaOH, whereas the same weight
of a monobasic acid, C^oH^gOj, requires 0-0435 NaOH.

5-Imino-2-cyano-l : 3-di7nethyl-6-amyl-3-hexyl-^^-cyc\ohexene-2-

carboxylic Acid, C^Hj^'CMe^pVr "rA>JTT\^^'^5^Q-

It is mentioned above that the residue remaining in the flask
after the distillation of the product obtained from the condensa-
tion of methyl hexyl ketone partly solidified, and this solid was found
to be an acid. It was further purified by dissolving in sodium
carbonate and reprecipitating with mineral acid, when a solid
separated. This was collected ^^and drained on porous porcelain, and
then recrystallised from methyl alcohol, from which solvent it

KETONES AND ALDEHYDES, ETC. 19G5

separates in almost colourless leaflets, melting and decomposing at
136 — 137°. The analytical results indicate that it is an imiuocijclo-
hexenecarboxylic acid, analogous to those previously described on
p. 1959, and, like these, it is unstable towards permanganate

0-1181 gave 03165 CO^ and 0-1009 U.fi. C = 73-l ; H = 9-5.

0-1172 „ 8-5 c.c. N, at 15° and 760 mm. N = 8-4.

CoiHg^OoNo requires C = 72-8 ; H = 9-8 ; N-8-1 per cent.

Hydrochloric acid effects the hydrolysis of the imino-group, forming
the corresponding hydroxycarboxylic acid.

a-Cya7io p(3-cliethylacrylic Acid, CEt2*C(CN)-C02H.

Ethyl sodiocyanoacetate was prepared by treating ethyl cyano-
acetate (28 grams) with sodium (5-7 grams) dissolved in alcohol, add-
ing diethyl ketone (21-5 grams) to the hot mixture, and boiling
the whole for two hours on the water-bath. The reaction proceeded
rather more slowly than in experiments with other ketones, and the
yield of oil obtained from the sodium carbonate solution was much
smaller. The product was worked up exactly as in other cases, and,
after some days, the oily acid deposited large crystals, which were
pressed on a porous tile and, when free from oil, recrystallised from
light petroleum, from which the substance separated in colourless,
elongated prisms melting at 55°. a-Cyano-fi^-diethylacrylic acid is
sparingly soluble in light petroleum, very soluble in benzene, ethyl
acetate, or alcohol.

A titration showed it to be monobasic : 0*1374 required 0 0360
NaOH, whereas the same weight of a monobasic acid, CgH^jOgN,
requires 0-0359 NaOH.

0-1474 gave 0-3431 COg and 0-0964 H2O. C = 63-4 ; H = 7'2.

0-1448 „ 11-2 c.c. N2 at 13° and 758 mm. N = 9-l.

CgHiiOoN requires C = 62-7 ; H = 7-2 ; N = 9-1 per cent.

The above cyano-acid is decomposed on distillation with elimination
of carbon dioxide and formation of P(i-diethylacrylonitrile, which is a
colourless oil distilling at 90°/25 mm. We were unable through lack of
material to prepare the corresponding /3/3-diethylacrylic acid by
hydrolysis of the nitrile :

0-1644 gave 190 c.c. N. at 16° and 745 mm. N= 13-1.
C^HjjN requires N= 12-8 per cent.

We desire to express our indebtedness to Prof. W. H. Perkin for
the interest he has taken in this investigation.

The University,

Manchester.

VOL. XCV. 6 O

196(j BARROWCLIFF AND TUTIN : CONFIGURATION OF TROPINE

CCX^ i. — The Configuration of Tropine and -^-Tropine,
arid the Resolution of Atrojnne.

By Marmaduke Barrowcliff and Frank Tutin.

The base tropine, obtained by the hydrolysis of the alkaloids
atropine and hyoscyamine, has been shown by Willstatter (Ber.,
189S, 31, 1534) to possess the following constitutional formula:

CHg-CH CH2

KMe . CH-OH .
CH./CH CH2

Liebermann (Ber., 1891, 24, 2332) obtained from Java coca leaves
an alkaloid, designated tropacocaine, which he proved to be the
benzoyl derivative of a base isomeric with tropine. This base has
been designated j/'-tropine, and Willstatter has shown (Ber., 1896,
29, 936) that it may readily be obtained from tropine by heating
the latter with sodium amyloxide.

Tropine and i/'-tropine both possess the same structural formula,
for, on oxidation, they each yield tropinone, whilst the latter, when
reduced, gives a mixture of the two hydroxy-bases (Willstatter and
Iglauer, Ber., 1900, 33, 1170). Willstatter concluded, therefore,
that a cis-trans-isonievism, dependent on the relative positions in
space of the hydroxyl and methyl groups, existed between tropine
and i/z-tropine. Objection to this explanation might be made on the
ground that no quite parallel case of isomerism seems to have been
observed, and it therefore appeared to the present authors that it
should not be accepted unreservedly so long as another explanation
is possible.

The tropine molecule contains two similar asymmetric carbon
atoms, and the base should therefore be cajDable of existing in a
racemic and an internally compensated form. The possibility of
these two optically inactive modifications being represented by
tropine and i/z-tropine had been considered by Willstatter, but he
rejected this explanation, as both bases, on oxidation, yielded the
same ketone. It seemed to the present authors, however, that the
possibility of the difference between tropine and i/z-tropine being
dependent on the configuration of the two asymmetric carbon atoms
was not entirely excluded, for each of these bases might undergo
racemisation during the process of oxidation, thus yielding identical
ketonic products. Tropinone would then be a mixture of the
racemic and meso-ketonic bases, and this would account for its
yielding both tropine and i/'-tropine on reduction. On the other

AND i/r-TROPINE, AND THE RESOLUTION OF Al'KOPINE. 1067

licind, if racemisation does not ot-cur during tlie oxidation of tropine
or i//-tropine, it was thought possible that two compounds so nearly
related as racemic and nieso-tropiuones might be so similar in
properties that their individuality had been overlooked.

In view of the above considerations, therefore, it would appear
that the formation of i/z-tropinc by the action of sodium amyloxide
on tropine might be a process of racemisation, and this seemed to
be in harmony with the experimental facts, since the change in
question is never complete. Thus, in our experiments on the pre-
paration of i/'-tropine, about 35 per cent, of the basic product
resulting from the treatment with sodivim amyloxide was found to
consist of an uncrystallisable mixture of tropine and j/'-tropine, and
Willstiitter mentions that the yield of pure i/'-base obtained by
him did not exceed 50 to 55 per cent, of that theoretically possible.
It appeared, therefore, that the action of sodium amyloxide on
tropine resulted in the formation of an equilibrium mixture of this
base and i/'-tropine, just as the action of alkali on pilocarpine or
/i'opilocarpine results in the j^roduction of an equilibrium mixture
of these two stereoisomeric bases (Jowett, Trans., 1905, 87, 794).
This, however, is not the case, since the change is irreversible, no
tropine being formed by the action of sodium amyloxide on
^-tropine.

Apart from the question of the relation of tropine to i/'-tropine,
the individual configuration of each of these bases requires to be
established. This point was considered by Ga'damer (^Arch. Pharni.,
1901, 239, 294), who drew the conclusion that tropine was internally
compensated, since hyoscyamine yielded inactive tropine, even when
hydrolysed only with water, and he did not consider it likely that
a naturally occurring compound would be partially racemic. Much
value should not, however, be attached to the grounds on which
Gadamer based his conclusions, for partially racemic compounds do
occur in nature, as an example of which prulaurasin may be quoted
(Herissey, Compt. rend., 1905, 141, 959). Moreover, as proved in
the present investigation, hyoscyamine always suffers some racemisa-
tion when liberated from its salts, and this change might occur in
the tropine part of the molecule. That is to say, that if free
hyoscyamine were partially racemic, the base, when in the form of
its naturally occurring salts, might, nevertheless, be a derivative of
optically active tropine.

With the object, therefore, of definitely establishing the con-
figuration of tropine and of i/'-tropine, we have conducted experi-
ments on the resolution of these bases, and some of their derivatives,
by fractionally crystallising their salts with certain optically active
acids. It may at once be stated that the results of these experi-

6 O 2

lf»68 BARROWCLIFF AND TUTIN : CONFIGURATION OF TROPINE

meats point to the conclusion that both the bases in question are
iuterually compensated compounds. The relation between them
must, therefore, be of the nature of a cis-trans-isoixievism, as con-
cluded by Willstatter {loc. cit.). Attempts were made to racemise
tropine by heating the latter at high temperatures with hydrochloric
acid, but these were unsuccessful.

ip-Tropine d-camphorsulphonate (m. p. 224 — 226°) and d-bromo-
ca»i2)horsuIphonate (m. p. 180°) were prepared and fractionally
crystallised, but no evidence of resolution could be obtained. The
normal and hydrogen d-tari rates were also prepared, but these salts
could not be crystallised. The d-camphorsulphonate (m. p.
176 — 177°) and d-hro7nocamphorsidphonate (m. p. 190°) of benzoyl-
i/'-tropeine were then prepared; these salts crystallised well, and
Avere submitted to a prolonged fractionation, but no separation could
be effected in either case.

Tropine d-camphorsulphonate (m. p. 236°) and hcnzoyltropcine
d-camphorsiilphojiate (m. p. 240°) were next investigated, and were
fovind, like the preceding salts, to be incapable of resolution.
Finally, tropinone was prepared, both from tropine and from
i/'-tropine, and the base obtained from each source was converted into
its (^-camphorsulphonate. The two preparations of tropinone
d-camjihorsulphonate (m. p. 216°) thus obtained were found to be
incapable of resolution, and were in all respects identical.

Further and conclusive proof that tropine is an internally com-
pensated compound was obtained by a study of the resolution of
atropine. This base is, of course, the tropine ester of cJ^tropic
acid, the latter containing one asymmetric carbon atom. Now,
if atropine is a derivative of internally compensated tropine,
it would, on resolution, yield only two bases, but if it is derived
from racemic tropine, it should be capable of resolution into four
stereoisomeric bases, or, at all events, in the latter case, it would
be possible to obtain proof of the existence of more than two
isomerides. Atropine d-camphorsulphonate was therefore jjrepared,
and submitted to fractional crystallisation. It was then found that
resolution was readily effected, but the operation yielded only two
salts, namely, d- and \-hyoscyamine d-camphorsulphonates. Atropine
must therefore contain only one racemic asymmetric carbon atom,
namely, that contained in the tropic acid molecule.

Z-Hyoscyamine <Z-camphorsulphonate melts at 159°, and the
specific rotation of the base contained in it, calculated from that
of the salt, is [o]d-32-1°. This figure is considerably higher than
any value previously obtained for the rotation of hyoscyamine, the
pure base being usually stated to have about [a]o-21-0°. It was,
however, found impossible directly to obtain from the camphor-

AN'D i/r-TROPIXE, AND THE RKSOLUTIOX OF ATROPINE. 1009

siilphonato a base of higher rotatory power than aboi;t [a]j, — 20'0°.
Tliat tliis decrease in optical activity was due to tlie fact that
racemisation liad occurred was proved })y reconverting tlie base
into the campliorsulplionate, when a rather impure product was
obtained, from wliich, by fractional crystallisation, it was possible
to separate the salt of a dextrorotatory base. A preparation of
Z-hyoscyamine having [aj^ — 25"8° was, however, obtained by frac-
tionally crystallising, from an anhydrous solvent, a quantity of the
base having [a]j, — 20"0°. The ease with which hyoscyamine under-
goes racemisation in presence of water is shown by the fact that
the rotation diminishes on allowing the base to remain dissolved
in moist chloroform. These observations render it evident that no
optically pure hyoscyamine has yet been obtained, and that, in all
probability, the only salts of this base which have been prepared
in a state of purity are those described in the present com-
munication.

^/-Hyoscyamine c/-camphorsulphonate was obtained pure only with
considerable difficulty. It melts at 135°, and yields a base possess-
ing properties similar to those of its optical antipode. r/-Hyos-
cyamine has not been observed to occur in nature, but it has been
obtained synthetically, although only in an impure state. Laden-
burg and Hundt {Ber., 1889, 22, 2590) prepared a base by com-
bining c?-tropic acid with tropine. This product they called
" ^/-atropine," btit more recent w-ork has rendered it evident that,
in reality, it was impure rZ-hyoscyamine. Amenomiya {Arch,
riiarm., 1902, 240, 498), employing a method similar to that used
by Ladenburg and Hundt, prepared a (^-hyoscyamine of greater
purity. This preparation had [a]p-i-23'0° when in the form of
its hydrochloride, the latter having been obtained from the auri-
chloride without liberation of the base. Amenomiya, however, did
not determine the rotation of the free base obtained from the salt
which he had thus prepared.

Particular interest is attached to the resolution of atropine,
inasmuch as it is known that the two stereoisomeric hyoscyamines
differ greatly in their respective physiological activities. Thus,
Cushny (.7. Phi/sinl., 1904, 30, 176) has shown that /-hyoscyamine
([a]p — 2r0°) has about fourteen times the activity of the ^/-hyos-
cyamine prepared by Amenomiya. The material employed by
Cushny was, however, not only partially racemised, but was also, in
the case of the (i-base, extremely limited in amount. A more
complete comparison of the physiological actions of the two
isomerides has therefore been made by Dr. P. P. Laidlaw,
at the Wellcome Physiological Research Laboratories, with the
employment of the optically pure r/-camphorsulphonates obtained

1070 r.ART^()\VCUFF AND TUTTN' : CONFTOTTRATIOy OF THOPINE

by tlie resolution of atropine. It has thus been rendered evident
that the two optical antipodes have, qualitatively, essentially the
same physiological action, and differ only in the intensity of their
effects. The ratio of activity of the /- to the c?-isonieridc has been
found, however, when employing the pure salts, to be much greater
than was indicated by Cvishny. Thus, the mydriatic action of
the former base was found to be about one hundred times that of
the latter, whilst the paralysis of the vagus induced by them was
in the ratio of 25 : 1, or possibly rather greater.

Experimental.
Tro'pine.

Tropine d-camj)hnrsul2Jhonate- — This salt is very readily soluble
in water or alcohol. It crystallises well, however, from a mixture
of alcohol and ethyl acetate, or from chloroform, giving large,
tabular crystals, melting at 236° :

01138 gave 0-2408 COo and 0-0871 H^O. C = 57-7; H = 8-5.
CsHi50N,Ci,jHic04S requires C = 57-9; H = 8-3 per cent.

The salt was fractionally crystallised under various conditions,
but no ai^preciable difference could be detected between any of the
resulting fractions :

0-3761, made up to 25 c.c. with chloroform, gave Op + 0° 58' in a
2-dcm. tube, whence [a]p+321°.

0-4123, made up to 25 c.c. with water, gave 0^ + 0° 27' in a
2-dcm. tube, whence [a]j,+ 13-6° and Mjj+50-6°.

Beyizoyltrofeine d.-cani'phorsul'phonate. — Benzoyltropeine was pre-
pared by Ladenburg (Annalen, 1883, 217, 82) by the interaction
of tropine and benzoic acid. An improved method of preparation
has recently been described by Jowett and Pyman (this vol., p. 1028),
who heated tropine hydrochloride with benzoyl chloride, thereby
obtaining 77 per cent, of the theoretical yield of benzoyltroj^eine
hydrochloride. The present authors, however, found that a prac-
tically theoretical jTield of the latter salt could be obtained in a
few minutes by employing free tropine instead of its hydrochloride.
The base was added to an excess of benzoyl chloride, and the
mixture heated to the boiling point of the latter. An additive
compound of the base and the acid chloride, analogous to the
corresponding compound obtained from pyridine, appeared first to
be formed, but, when the temperature was raised, this soon re-
dissolved, whereupon the hydrochloride of the benzoylated base
rapidly separated. The cooled mixture was then diluted with
ether, and the hydrochloride collected. After being once crystal-
lised from alcohol, it melted and decomposed at 267° (uncorr.).

AND i/r-TROPINE, AND THE RESOLUTION OF ATROPINE. 1 !»7 1

Benzoyltrn2)c'ine d-cam^ihorsuJ^^honate crystallises readily from a
mixture of ethyl acetate and alcohol, forming small, flattened
needles, which melt at 240° :

0-1131 gave 0-2600 CO. and 00773 lIoO. C = G2-7; H = 7-6.
Ci.-,Hj90oN,C,oHicO.^S requires C = 62-9; H = 7-3 per cent.

0-4012, made up to 20 c.c. with water, gave a^ + Q° 2G' in a
2-dcm. tube, whence [a]p+ 10-8° and Mp + 5r5°.

The salt was submitted to a very thorough fractionation, but no
resolution could be effected.

xp-Trofine.

xp-Tvo-^mc was prepared according to the method described by
Willstatter {Ber., 1896, 29, 936). The base was purified by dis-
tillation, followed by crystallisation from a mixture of benzene and
light petrole^^m. The mother liquors from the first crystallisation
contained a quantity of oily material, amounting to about 35 per
cent, of the total product. As this could not be crystallised, it
was benzoylated by heating with benzoyl chloride, and the resulting
hydrochloride of the benzoylated product crystallised from alcohol.
The material thus obtained formed colourless needles, melting at
241°, and appeared to be quite homogeneous; it yielded a picrate
melting at 216 — 217°. The product, however, was found to be a
mixture of the hydrochlorides of benzoyltropeine and benzoyl-
j/'-tropeine, apparently in equal proportions, since, by the addition
of siiccessive portions of picric acid solution, it first yielded
benzoyltropeine picrate (m. p. 249 — 250°), and finally benzoyl-
j/'-tropeine picrate (m. p. 238—239°).

ip-Tropine d-camjjhorauljihonate. — This salt crystallised readily
from a mixture of alcohol and ethyl acetate, forming flat prisms,
which were anhydrous, and melted at 224 — 226°:

0-1101 gave 0-2337 CO., and 0-0842 HoO. C = 57-8; H = 8-5.
CgHijON.CioHjcP^S requires C = 75-9; H = 8-3 per cent.

j/'-Tropine r/-camphorsulphonate is very readily soluble in water,
ethyl, methyl, and aniyl alcohols, and in chloroform, but only very
sparingly soluble in ethyl acetate, acetone, benzene, or toluene.
It was fractionally crystallised from both cold and boiling solvents,
but no evidence of resolution could be obtained :

0-4682, made iip to 25 c.c. with alcohol (98 per cent.), gave
au + 0° 59' in a 2-dcm. tube, whence [a\^+2%-2>°.

0'4119, made up to 25 c.c. with water, gave Oj)-hO° 27' in a
2-dcm. tube, whence [a]p+13-7° and Mp-f51-2°.

x(/-Tropine d-hrninocamj)horsidj)honate. — The ?olubilitifs of this
salt are similar to those of the corresponding cZ-camphorsulphonate.

1972 riARROWCLIFF AND TUTIN : CONFIGURATLON OF TROPINE

It is deposited from cool, saturated solutions in large prisms, but
separates from a boiling mixture of ethyl acetate and alcohol in
line needles. When anhydrous it melts at 180°, but it separates
from moist solvents in needles, which contain one molecule of water
of crystallisation, and melt at 112°:

0-9388 of hydrated salt, on heating at 100°, lost 0-0344 HgO.

H.O = 3-7.
0-1269" of anhydrous salt gave 0-2229 COo and 0-0788 HgO.
C = 47-9; H = 6-9.
C8Hi50N,CioHjABrS,H.O requires H20 = 3-8 per cent.
C8Hi50N,CioHi504BrS requires C = 47-8; H = 6-6 per cent.
0"4457 of anhydrous salt, made up to 25 c.c. with chloroform,
gave a^+1° 28' in a 2-dcm. tube, whence [o]i3+69-l°.

0-5030 of anhydrous salt, made up to 25 c.c. with water, gave
Oi, + 2° 26' in a 2-dcm. tube, whence [a]D+60-5° and Md + 273-3°.

Prolonged fractional crystallisation of this salt gave no evidence
of resolution.

Benzoyl-rp-tropeine d-ca7iiphorsulphonate. — Benzoyl-i/'-tropeine
(tropacocaine) was prepared in a manner similar to that employed
for the preparation of benzoyltropeine ; the yield was practically
quantitative. The hydrochloride of the base was found to melt at
283° (uncorr.), a temperature 12° higher than that recorded by
Liebermann (loc. cit.) and by Willstatter (loc. cit.) for the melting
point of benzoyl-i/'-tropeine (tropacocaine) hydrochloride. The
aurichloride melted at 208°, and was analysed :

0-1391 gave 0-0468 Au. Au = 33-6.

Cj5Hj902N,HAuCl4 requires Au = 33-7 per cent.

Benzoyl-\p-tropeine d-camyhorsul'pJionate crystallises very readily
fx-om a mixture of ethyl acetate and alcohol, forming large prisms,
melting at 176 — 177°:

0-1236 gave 0-2846 COo and 0-0823 HoO. C = 62-8 ; H = 7-4.
Ci5Hj902N,CioHjg04S requires C = 62-9; H = 7-3 per cent.

0-5412, made up to 20 c.c. with water, gave aD + 0° 36' in a
2-dcm. tube, whence [a]p+ll-l° and Md + 51-8°.

The salt was separated into a large number of fractions, but no
evidence of resolution could be obtained.

Benzoyl-\p-tro'peine d-hromocam'phorsul'phonate. — This salt differs
from the sulphonates above described, inasmuch as it forms a
hydrate which is only sparingly soluble in cold water. This
compound forms slender needles, which melt at 73° :

0-5420, on drying at 123°, lost 00464 HgO. H20 = 8-6.
C,r,H,902N,CioHi504BrS,3H20 requires H20 = 8-8 per cent.

AXD -v/r-TROPlXE, AXD THE RESOLUTIOX OF A'lTtOPIXE. IftT.S

The anhydrous salt crystallises readily from a mixture of ethyl
acetate and alcohol, and forms thin prisms, which melt at 190°:

0-1401 gave 0-2779 CO., and 00794 ILO. C = o4-l ; H = 6-3.
C,,r,H,oOoN,C,oH,.^O.iBrS requires C = 54-0; 11 = 6-1 per cent.

0-4827, made up to 20 c.c. with water, gave a^ + 2° 17' in a
2-dcm. tube, whence [o]d + 47-3° and M^ 4- 262-9°.

This result for the molecular rotatory power is rather lower than
would have been expected for the bromocamphorsulphonate of an
inactive base. Nevertheless, the base was devoid of optical activity,
and the discrepancy can only be ascribed to the fact that the
solutions examined were highly supersaturated. The salt was
separated by crystallisation into a number of fractions, but all of
these had the same rotatory power and melting point.

Trojnnone.

Tropine and j/'-tropine were each separately oxidised to tropinone,
according to the method described by Willstatter (Be?-., 1896. 29,
393), and the resulting base purified by means of the picrate.
Willstatter states that this salt melts at 220°, but the present
authors find that the temperature of fusion is dependent on the rate
of heating, and may lie at any point from 210—250°. Each pre-
paration of the base was converted into the d-camphorsiilphonafe,
when the resulting salts were found to be in all respects identical.

Tropinone <^-camphorsulphonate is fairly readily soluble in dry
ethyl acetate, from which it crystallises in moss-like growths,
apparently composed of needles; it melts and decomposes at 216°:

0-1130 gave 0*2421 COo and 0-0830 H.O. C = 58-4; H = 8-l.
CsHjgON.CioHjcO^S requires C = o8-2; n = 7-9 per cent.

The salt is much less soluble in ethyl acetate which has not been
specially dried, and crystallises from this solvent in tufts of leaflets,
which, when rapidly heated, suddenly lose water of crystallisation at
140°, but without completely melting:

2-0429, on heating at 123°, lost 0-0939 HoO. HoO = 4-6.
C8Hj30N,CjoHj604S,HoO requires Hob = 4-6"per cent.

The hydrated salt appears to be dimorphous, since, at low tem-
peratures, it crystallises from a mixture of ethyl acetate and dilute
alcohol in long, slender prisms.

No resolution of tropinone c/-camphorsulphonate could be effected
by fractional crystallisation.

107+ BARROWCLIFF AND TUTTN : CONFIGURA.TIOX OF TROPINE

The Resolution of Atropine.

Foi'ty grams of atropine were neutralised with rZ-camplior-
sulphonic acid, and the resulting salt was fractionally crystallised
from ethyl acetate containing some alcohol. The first crop of
crystals consisted of prismatic needles, and melted at 136 — 140°.
This was recrystallised several times until no further change
occurred ; it then melted at 159°.

0'5072, made up to 25 c.c. with water, gave a^ — 0° 19*5' in a
2-dcm. tube, whence [a]p-S-0° and Mj5-4r7°.

Since the molecular rotation of c/-camphorsulphonic acid is + 51°,
it is evident that the basic ion of the above salt has Mp — 92"7°,
which corresponds with a specific rotatory power of — 32'1°. It is
seen, therefore, that resolution had been effected, and that the salt
melting at 159° was \-hyoscy amine d-camphorsvlj^/ionate :

0-1302 gave 0-2974 COo and 0-0902 HoO. C-62-3; H = 7-7.
C];Hoo03N,CioHic04S" requires C = 62-4; H-7-5 per cent.

For the purpose of comparison a quantity of natu.ral ?-hyos-
cyamine was converted into the rZ-camphorsuliohonate. The salt so
obtained melted at 149 — 150°, and was somewhat impure; after
recrystallisation, however, it melted at 159°, and was identical with
the salt obtained from atropine. /-Hyoscyamine rZ-camphor-
sulphonate is extremely readily soluble in water, alcohol, or chloro-
form, and very sparingly soluble in ethyl acetate, benzene, or
xylene. The material contained in the mother liquors obtained
during the separation of the Z-hyoscyamine rZ-camphorsulphonate
from the original atropine salt, which would contain the salt of
(Z-hyoscyamine, was submitted to a very elaborate process of frac-
tional crystallisation, whereby it was shown conclusively that the
salts of only two bases were present. The product did not crystal-
lise readily, and exhibited a considerable tendency to separate as
an oil. After a large number of crystallisations, however, the salt
of the d-hase was obtained in a state of purity.

d-TIyoscyamine d-camjiJiorsulphonate forms small needles, which
melt at 135°. Its solubilities are similar to, but rather greater
than, those of the corresponding Isevo-salt:

0-1212 gave 0-2793 COg and 0-0840 HoO. C-62-1; H = 7-7.
Cj7H2303N,CioHir,04S requires C = 62-4; H = 7-5 per cent.

0-5229, made up to 20 c.c. with water, gave ap+l° 25-5' in a
2-dcm. tube, whence [ajj^-f- 27*25° and Mi,+ 143-7°.

From this result it is calculated that the basic ion has Md-1-92-7°
and [a]p+321°, figures which are in exact agreement with the
corresponding values obtained for the /-base.

AND -v/r-TROPTNF, WH TTTE HESOLTTTIOX OF ATROPINE. 1075

It would appear, therefore, that the respective bases containerl
in the above-described pure <^/-camphorsulphonates have a specific
rotation of [a]p + 32"l°, a value coiisidcrably higher than that
usually given for hyoscyamiiio (about — 21'0°). It was, however,
found impossible to obtain directly from either of the camphor-
sulphonates in question a base of higher specific rotatory power
than about [ a]„ + 20'0°, even when the greatest care was taken to
avoid raccmisation. That this change, nevertheless, had occurred
to some extent was shown by reconverting a quantity of the base
having [aj^ — 20"0° into the rZ-camphorsulphonate, when a somewhat
impure salt was obtained, from which the derivative of a dextro-
base was separated. A considerable quantity of the loevo-base,
having [o]j) — 20'2°, was fractionally crystallised from petroleum
(b. p. 90 — 120°), when a fraction was eventually obtained which
melted at 107 — 108°, and had the following rotatory power:

0"4331, made up to 20 c.c. with 50 per cent, alcohol, gave
Op — 1° 1' in a 2-dcm. tube, whence [aj^ — 25'8°.

This is a higher value than has heretofore been observed for
the rotation of hyoscyaminc.

rZ-IIyoscyamine, obtained from its r/-camphorsulphonatc, was in
all respects analogous to its optical antipode.

As it appears probable from the above results that optically pure
hyoscyamines have never been obtained in a free state, several salts
of these bases were prepared by double decomposition from the
pure <:/-camphorsulphonates. Corresponding salts of atropine have
also been made for the purpose of comparison.

The Avrichlorides. — ?-Hyoscyamine aurichloride has previously
been described as forming leaflets, melting at 162° (Will, Ber.,
1888, 21, 1717). The pure salt forms golden-yellow, hexagonal
plates, which melt at 165°, and are anhydrous:

0-1244 gave 0-0391 Au. Au- 31-35.

Cj7ll2303N,HAuCl4 requires Au = 3r35 per cent.

Z-Hyoscyamine aurichloride is miich more soluble in alcohol than
in water, but can readily be crystallised from the former solvent.

Somewhat impure .'/-hyoscyamine aurichloride was prepared by
Amenomiya {loc. cit.). The pure salt crystallises similarly to its
optical antipode, melts at 165°, and is anhydrous:

0-1198 gave 0-0374 Au. Au = 31-22.

Cj7H2303N,HAuCl4 requires Au = 31'35 per cent.

Atropine aurichloi'ide showed some tendency to separate as an
oil, but crystallised fairly readily. It formed tufts of very small,
anhydrous leaflets, which melted at 134 — 139°:

0-0926 gave 0-0292 Au. Au = 31-5.

Cj7H2303N,HAuCl4 requires Au = 3r35 per cent.

1<)76 CONFIGURATION OF TROriXE AND -v/r-TnOPINE.

The Anribro7}iides. — /-Hyoscyamine auribromide was first pre-
pared by Jowett (Trans., 1897, 71, 679), who stated that it melts
at 115 — 120°, and regarded it as being anhydrous. The present
authors find that the pure salt separates from water with one
molecule of water of crystallisation, and, when dried in the air,
melts at about 123 — 130°. The anhydrous salt, on heating, sinters
slightly at 155°, after which it fuses sharply at 160°, without
decomposition. The salt is even more sparingly soluble in water
than the corresponding aurichloride, and crystallises in very long,
highly lustrous, flattened needles, possessing a deep red colour. It
dissolves much more readily in absolute alcohol than in water, and
crystallises from the former solvent with one molecule of alcohol :
2'0350, crystallised from water, on heating at 110°, lost 0"0418

HoO. H20 = 21.
0-3029, crystallised from alcohol, on heating at 110°, lost 0-0158

Eton. EtOH = 5-2.
0-1210 of anhydrous salt gave 0-0294 Au. Au = 24-3.

Ci.H2303N,HAitBr^,HoO requires HoO = 2-2 per cent.
Cj;H2303N,HAuBr4,EtOH „ EtOH = 5-4
Ci7H2303N,HAuBr4 „ Au = 24-3

d-Hyoscyamine auribromide has not joreviously been obtained.
It agrees in all respects with the description of the corresponding
Isevo-salt given above :

0-2197 of hydrated salt, on heating at 110°, lost 0-0044 HoO.

H2O = 2-0.
0-0966 of anhydrous salt gave 0-0235 Au. Au = 24-3.

Ci7H2303N,HAuBr4,H20 requires H20 = 2-2 per cent.
CjjH.^aOsN.HAuBr/ „ Au = 24-3

Atropine auribromide was described by Jowett (loc. cit.), who
considered it to be anhydrous, and stated that it crystallised in
chocolate-colovired prisms melting at 120°. The salt, as prepared
by the present authors, does not crystallise nearly so readily as
the corresponding derivatives of the hyoscyamines. It forms very
small tufts of dark red needles, which contain one molecule of
w-ater of crystallisation, and, when air dried, forms a crystalline
powder, melting at 110°. The anhydrous salt fuses at 120°:

0-1225, on heating at 100°, lost 0-0027 H2O. HoO = 2-2.

0-1082 of anhydrous salt gave 0-0263 Au. Au = 24-3.
Ci7H2303N,HAuBr4,H20 requires HoO = 2*2 per cent.
Ci7H2303N,HAuBr4 „ Au = 24-3 „

T7ie, Pierates. — The picrates of ^hyoscyamine and atropine are
mentioned in the literature, but their melting points have not been
recorded. d-TIyoscyamine picrate has not previously been prepared.

SYNTHESIS OF COTARNIC ACID. 1077

Both d- and /-hyoscyamine picrates crystallise fairly readily,
formiug ueedles, which melt at 163°, without decomposition.
Atropine j^icrate crystallises much more readily than the correspond-
ing salts of either of the active bases, and forms rectangular plates,
which melt at 173—174°.

TiiF. "Wellcome Chemical Reseakch Lauuuatories,
London, E.G.

CCXA'II. — Synthesis oj Cotarnic Acid.

Dy William Henry Perkin, jun., Houert Kobinson, and Frederick

Thomas.

During the course of an investigation on narcotin and its degradation
products, on which we have been engaged for a considerable time, we
have carried out a series of experiments which have resulted in a
synthesis of cotarnic acid, and have thus definitely established the
constitution of this important acid.

Wuhler {Annalen, 1844, 50, 19) lirst obtained cotarnine, CjoHj^O^N,
from narcotin, C.,2H230-N, by oxidation with manganese dioxide and
dilute sulphuric acid, and tlie careful investigation of this important
substance has shown that it is probably an aldehyde of the
constitution :

CH2:02:C^H(OMe)(CHO)-CHo-CH2-NHMe.

Furthermore, the experiments of Freund and Becker {Ber., 1903,
36, 1521) have made it probable that the methoxy -group in cotarnine
is adjacent to the aldehyde group, and the above formula may there-
fore be expanded to (A) :

OMe OMe

or ^cHo ^,TT ^or >cOoH

OH <^^\ r^^ f'H <'

^01 ;CH,-CH.-NHMe ^^2^0' JCO.H

(A) (B)

When cotarnine is oxidised with permanganate, it yields cotarnic
acid, Cj^HgO-, and if the constitution for cotarnine just given is
accepted as correct, the constitution of cotarnic acid will be
represented by the formula (B), and this acid is therefore methoxy-
hydrastic acid.

The highly ingenious method which Freund and Becker have
employed to show that cotarnine is a derivative both of piperonal and

1978 PERKIN, ROBINSON, AND THOMAS

of salicylaldehyde methyl ether, as indicated in the formula just
mentioned, does not appear to us to be quite conclusive, and we have
therefore confirmed this formula by synthesising cotarnic acid by a
method which leaves uo room for doubt as to its constitution.

The synthesis proved to be a difficult one, but after many un-
successful attempts in other directions, we ultimately succeeded in
solving the problem by a process which is briefly as follows :

The starting point was 5 : G-methylenedioxy-1-hydrindone, which
we prepared in quantity from 3 : 4-methylenedioxyphenylpropionic
acid by the action of phosphoric oxide :

CH2<q| Ich„-CH,-CO.,H ""^ ^^2<ol JcH^^^

2 -^-^o^ v^\ /^-"2

(compare Perkin and Hobinson, Trans., 1907, 91, 1084),

When this substance is treated with concentrated nitric acid, it
is readily converted into l-nilro-6 : 'o-melhylenedioxy-l-hydrindoit.e
(m. p. 164—165"),

NO2

CH,<^

and this is reduced by tin and hydrochloric acid with formation of
the corresponding amino-derivative, m. p. 175° (I). The next step
was to convert the amino-derivative into l-hydroxy-b : 6-methylenedioxy-
l-hydrindone (II) by diazotisation, and although, owing to the forma-
tion of brown by-products, the yield of the hydroxy-derivative was
very small, we succeeded in obtaining sufficient for our purpose.

This hydroxy-derivative yields an intense violet coloration on the
addition of ferric chloride to the alcoholic solution, and the hydroxy-
group is therefore most probably adjacent to the carbonyl group. It
was for this reason that we assign the position 7 to the nitio-group
in 7-nitro-5 : 6-methylenedioxy-l-hydrindone.

By treatment in alkaline solution with methyl sulphate, the
hydroxy-derivative was next converted into the corresponding
met/wxy-deriva.tive (111), and this, when condensed with piperonal
and dilute aqueous potassium hydroxide, yielded 7 - methoxy-
5 :6-melhylenedioxy-2-pi/jeronylidene-l-hydrmdone (m. p. 225 — 230°,
IV).

This piperonylidene derivative was oxidised by permanganate, and
the acid produced was recognised as cotarnic acid (V) by conversion
into the characteristic methylimide, which melted at 205°, and had the
!-ame properties as a specimen of the methylimide of cotarnic acid
which we prepared from cotarnic acid obtained by the oxidation of

SYNTHESIS OF COTAllXIC ACID. 1979

cotarnine. The steps in this synthesis of cotarnic acid are therefore
the following :

NH, OH

(I.) (II.)

OMe OMe 0-CH

(III.) (IV.)

OMe

^^2^0' 'co;h

(V.)

The yield of cotarnic acid obtained in this way is, unfortunately,
very small, and we are engaged in an attempt to discover a more
satisfactory method of synthesis.

Nitration of the Methylene Ether of Catechol.

The methylene ether of catechol has been prepared by Moureu
{Bull. Soc. chini., 1896, [iii], 15, 654) by the action of methylene
iodide on the sodium derivative of catechol. Since we wished to
investigate the constitution of its mononitro-derivative, we have
endeavoured to use the cheaper methylene chlox'ide in its preparation,
and we find that the methylene ether can be so produced, but the yield
is very unsatisfactory. Catechol (66 grams) was dissolved in absolute
alcohol and mixed with a solution of sodium (27"6 grams) in alcohol
and methylene chloride (50 grams). After boiling for sixteen hours in
a reflux apparatus, the bulk of the alcohol was distilled off, water was
then added, the oil extracted with ether, and the ethereal solution
dried and evaporated. The residue consisted almost entirely of an oil
which distilled at 170 — 175*^ under the ordinary pressure, whereas the
boiling point of the methylene ether of catechol is stated by Moureu
{loc. cit.) to be 172 — 173°. A small quantity of this substance
was dissolved in glacial acetic acid and treated with a little nitric acid,
when the nitro-derivative separated and, after crystallisation from
alcohol, had the correct melting pointy 147". Its constitution was
proved as follows : The nitro-compound was readily reduced by tin
and hydrochloric acid, and the resulting base was obtained by rendering
the solution alkaline with potassium hydroxide and extracting with
ether. The base was converted, by warming with acetic anhydride,

inSO PEUKIN, ROBINSON, AND THOMAS:

into the acetylamino-compound, which crystallised from water in
colourless needles and melted at 135°.

Since the melting point was unaltered by admixture with the acetyl-
amino-derivative of the methylene ether of catechol, which is obtained
by the successive action of potassium hypobromite and acetic anhydride
on the amide of piperonylic acid, it is clear that the nitro-compound
produced by the nitration of the methylene ether of catechol is
4:-nit7'o-l : 2-methylenedioxybenzene,

Salway (this vol., 1155) has already shown that one of the products of
the nitration of piperonal has the same constitution.

7-Nitro-5 :Q'dwiethoxy-l'hydrindone, ^r r\\ IpH -^

In order to pi'epare this substance, 5 : G-dimethoxyhydrindone
(Perkin and Robinson, Trans., 1907, 92, 1092, 2 grams) was stirred
vigorously with nitric acid (D r42, 10 c.c), when the whole dissolved,
and, if the hydrindone was quite pure, no oxidation occurred.

After adding water, the sticky mass which separated gradually
became hard, and was collected and washed with water.

This nitro-compound crystallises fi'om a mixture of ethyl acetate
and light petroleum in pale yellow prisms, or from methyl alcohol,
in which it is very sparingly soluble in the cold, in almost colourless,
prismatic needles. If the hot saturated solution in methyl alcohol is
I'apidly cooled, needles separate, and after some time these change into
prisms :

01681 gave 8-4 c.c. Ng at 15° and 771 mm. N = 6-0.
CjjHj^OgN requires N = 5-9 per cent.

7-Nitro-5 : Q-dimethoxy-l -hydrindone melts at 149 — 150°, and, as the
following experiments show, exhibits the characteristic properties of a
derivative of hydrindone. (I) The solution in hot methyl alcohol was
treated with piperonal and a little potassium hydroxide, when a yellow
colour was immediately produced and a canary-yellow, crystalline
precipitate of the piperonylidene derivative quickly separated. This
substance may be recrystallised by adding methyl alcohol to its
solution in hot pyridine, and the pale yellow prisms thus obtained melt
at '260° with slight previous darkening. The colour of its solution in
concentrated sulphuric acid is intense reddish-purple, and becomes
yellow on dilution with water.

i

SYNTHESIS OF COTARNIC ACID. 1981

(II) Approximately equal weights of the nitro-hydrindone and of
salicyhildehyde were dissolved in methyl alcohol, and a rapid stream of
hydrogen chloride passed through the solution for a minute.

On cooling, brick-red crystals of the oxonium anhydro-hydrochloride
separated from the solution. This salt dissolves in water or con-
centrated sulphuric acid Jbo yellow solutions which do not fluoresce.

Tlie double salt with platinic chloride crystallises in orange,
microscopic needles. The anhydro-ferrichloride melts at 188°, and is a
brick-red precipitate, which crystallises from glacial acetic acid in
orauge-brown needles with chaiacteristic prismatic edges.

This ferrichloride has analogous properties to the similarly con-
stituted substances already described by Perkin, liobinson and Turner
(Trans., 1908, 93, 1085), and there can be little doubt that it has the
constitution

FeCl,
NO, O

MeO
MeO

l-Nitro-^ : Q-methjlenedioxjj-l-hi/drindone,

CH.<:^: jg&:>cir.

I

This substance may be prepared by adding nitric acid (D 1*42, 15 c.c),
previously boiled to remove nitrous acid, to 5 : 6-methylenedioxy-l-
hydrindone (Trans., 1907, 91, 1084). The hydrindone dissolves and,
after two minutes, water is added, and the precipitated nitro-compound,
-which rapidly hardens, is collected, washed, dried, and then purified by
repeated extraction with boiling light petroleum (b. p. 60 — 70°) :

0-1507 gave 8-5 c.c. Ng at 10° and 749 mm. N = 6-G.
C^oH705N requires N = 63 per cent.

7-Nitro-5 -.Q-methylenedioxij-l-hi/drindone melts at 164 — 165°, and,
if pure hydrindone was employed in its preparation, it may be readily
crystallised from methyl alcohol, from which it separates in very pale
elongated prisms. The colour of the solution in sulphuric acid is only
pale yellow, which is rather remarkable in view of the fact that 5 : 6-
methylenedioxyhydrindone itself dissolves in sulphuric acid with an
intense red coloration.

The piperonylidene derivative, prepared in the usual way, separates
in lemon-yellow, microscopic needles, which are very sparingly soluble
in alcohol and melt at 290° with decomposition. It is soluble in boil-

VOL. XCV. 6 P

i;»,s2 I'KitKiN, Koinxsox, and thomas :

ing glacial acetic aciil, and, on the addition of hydrochloric acid, a red
colour is produced, which disappears as the substance cryotallises from
the solution. The colour of the solution of the piperonylidene
derivative in sulphuric acid is purple.

7-A}nino-5 : Q-meihylenedioxi/-\-hi/ IrinJoiie,
KH,

The reduction of 7-nitro-5 : 6-methylenedioxy-l-hydrindone to the
corresponding amino-derivative may be carried out by gently boiling
its alcoholic solution for two hours with alcohol (200 c.c.) and hydro-
chloric acid (22 5 c.c.) with excess of tin. The product is then poured
into dilute hydrochloric acid, filtered hot from insoluble matter, and
the tin eliminated by treatment with hydrogen sulphide. As soon as
the liquid smells strongly, it is filtered, and the clear solution rendered
alkaline with sodium hydroxide, when a finely divided precipitate
separates, which is collected, dried on porous porcelain, and crystal-
lised from methyl alcohol. O.ving to the various by-products, the
yield was, unfortunately, only about 10 per cent, of that theoretically
possible :

01612 gave 10-4 c.c. N.^ at 13° and 746 mm. N = 7-5.
CjoH^jOgN requires N = 7'3 per cent.

7-Amino 5 : ^-mtthylenedioxy-\-hydrindone separates from methyl
alcohol in colourless needles, and melts at 175°. It yields, with
piperonal and alcoholic potassium hydroxide, a bright yellow, crystal-
line piperonylidene derivative, which doubtless has the constitution

"^2 O-CH,

since, on treatment with sodium nitrite and hydrochloric acid in
excess of alcohol, a solution is obtained which gives a red colora-
tion with alkaline ^-naphthol. Aminomethylenedioxyhydrindone
dissolves slowly in dilute hydrochloric acid, and the colourless
solution becomes yellow on the addition of sodium nitrite.

On adding this to an alkaline solution of /3 naphthol, a crimson
solution is obtained, from whicii a scarlet azo-compound separates.

This azo-compound dissolves in concentrated sulphuric acid with an
intense indigo-blue colour.

SYNTHESIS OF COTAKNIC ACID. 1083

OMe
oi/ntnesis oj Lotarnxc AciU, y^ii .1*^(^1 'po'H'

I

The conversion of 7-amino-5 : 6-methyIenedioxy-l-hydriudone into
cotarnic acid proved to be a much more difficult opei-ation than was
expected, owing principally to the formation, even under the best
condition?, of large quantities of other substances and consequent
small yield of the acid. After several comparative experiments, the
synthesis was ultimately accomplished in the following way.

Aminomethylenedioxyhydrindone (10 grams) was dissolved in the
least possible quantity of warm dilute hydrochloric acid and cooled
with ice, when some of the hydrochloride of the base separated.

Sodium nitrite (3'5 grams), dissolved in a little water, was then
added, the solution vigorously boiled for ten minutes, filtered,
saturated with ammonium sulphate, and repeatedly extracted with
ether.

The solution, mixed with alcohol, gave an intense violet coloration *
on the addition of ferric chloride, indicating that the hydroxy-
methylenedioxyhydrindone produced probably contains a hydroxy-
group in the ortho-position with respect to the carbonyl group (com-
pare p. 1978). Unfortunately, the conversion of the amino- into the
hydroxy-group is always accompanied by the formation of an in-
soluble, brown substance, which could not be crystallised, and greatly
affects the yield of the hydroxy-derivative. The ethereal solution
of the hydroxy-derivative was extracted with small quantities of dilute
potassium hydroxide, and the alkaline solutions agitated in the cold
with methyl sulphate in excess. When all the methyl sulphate had
been decomposed, the solution was extracted with ether and the
ethereal solution evaporated. The residue showed a tendency to
crystallise, but, as the whole of the material was required for the
synthesis, the product was not directly investigated, but, at once,
dissolved in alcohol and treated with piperonal and some dilute
potassium hydroxide. The yellow precipitate so obtained undoubtedly
consists of l-methoxy-6 : %-methylenedioxy-2-piperonylidene-\-hydrindone
(IV, p. 1979).

It maybe crystallised from a mixture of pyridine and alcohol, melts
at 225 — 230°, and dissolves in sulphuric acid, yielding an intense
carmine solution. The substance obtained from five of the above
operations was oxidised, at as low a temperature as possible, with

* On one occasion, the reaction, for some unknown reason, proceeded in another
direction, and the ether extract contained a substance which yielded a green colora-
tion with ferric chloride.

6 P 2

1984 SYNTHESIS OF COTAUNIC ACID.

potassium permauganate containing a small quantity of potassium
carbonate, but oxidation proceeded, especially at first, with difficulty,
owing largely to the insolubility of the substance. After a considerable
amount of permanganate had been reduced, the solution was boiled,
filtered, the manganese precipitate treated with hob water and sulphur
dioxide, and the unchanged piperonylidene derivative collected and
again oxidised with permanganate, the operation being repeated until
only a negligible amount remained unoxidised.

The alkaline filtrates from the manganese precipitates were combined,
evaporated to a small bulk, the solution was then rendered acid to
Congo-paper, and the small quantity of piperonylic acid which
separated removed by filtration. The filtrate was evaporated to
dryness, extracted with pure dry ether in a Soxhlet apparatus, and,
after distilling off the ether, a small quantity of a syrupy acid
remained, which quickly crystallised, apparently in plates. The
quantit}' was so small that an analysis was not attempted, and as
the melting point of cotarnic acid is nob sufficiently decisive, the whole
was converted into the methylimide which we had previously prepared
from a specimen of cotarnic acid from cotarnine and found to be highly
characteristic. In this experiment, the crude acid was dissolved in a
little hot water, when it was noticed that the solution, on cooling,
deposited crystals exactly resembling those of cotarnic acid. Excess
of methylamine was now added, the solution evaporated to dryness on
the water-bath, and the methylamine salt heated in a test-tube, when
a sublimate of needles was obtained and an oil distilled which soon
solidified. The distillate and sublimate were dissolved in a little
boiling methyl alcohol, when the filtered solution deposited a crop
of almost colourless needles, which melted at 205°, and had all the
properties of the methylimide of cotarnic acid, the identity with which
was further confirmed by the fact that an intimate mixture of the
two preparations melted sharply at 205'^. There can thus be no doubt
that the substance synthesised in the experiments described above was
cotarnic acid.

The University,

Manchester.

I

CONSTITURNTS OF TTIE FKriT OF KOMArj.TUM F.LATERirM. 1985

CCXVIII. — The Constituents of the Fruit oj FchaUiam

Elater'ium.

By Frederick Belding Power and Charles Watson Moore.

In a recent communication by the authors, entitled "Chemical
Examiuation of Elaterium and the Characters of Ehxterin " [Pharm.
J., 1909, [iv], 29, 501), it was shown that the product known and
officially recognised as '•' elaterin " is not homogeneous, but that it con-
sists, to the extent of 60 — 80 per cent., of a crystalline substance which
is completely devoid of the specific physiological action attributed
to elaterin, and may be separated by a process of fractional
crystallisation. This crystalline substance, which is much more
highly Igevorotatory and has a higher melting point than the crude
elaterin, is accompanied in the latter by a compound of apparently
the same percentage composition, but which possesses a vei'y high
degree of physiological activity and is dextrorotatoi'y.

In view of the fact that the elaterium from which the above-
mentioned " elaterin " is obtained represents only the material which
is deposited from the juice of the fruit of Ecballium Elaterium, it
appeared desii'able that the entire fresh fruit should be subjected to
a chemical examination in order to ascertain the nature of all its
constituents. In conducting this investigation, special consideration
has been given to the statement of Berg {Bull. Soc. chim., 1897, [iii],
1 7, 85) that elaterin does not pre-exist in the fruits of Ecballium, but
that it is formed, after the expression of the juice, by the action of a
ferment on an amorphous glucoside. The results which have now
been obtained, with the deductions from them, are summarised at the
end of this paper.

Experimental.

The material employed in this investigation consisted of the fresh,
nearly ripe fruits of Ecballium, Elaterium, A. Richard, which were very
kindly supplied to us by Messrs. W. Ransom & Hon, of Ilitchin.
They were collected during the latter part of August.

Separation of an Enzyme.

It has been indicated by Berg (Joe. cit.) that the juice of the fruit of
Ecballium contains an enzyme, or possibly a mixture of enzymes,
which -is capable of hydrolysing amygdalin, saccharose, and starch,
and was designated by him as elaterase. In order to obtain this
substance, the expressed juice from 3 kilograms of the fruit, amount-

lOSG PdWFR AND MOORE: THE CONSTITUENTS OF

ing to about 900 cc, w.as filtered, and mixed with 1500 c.c. of strong
alcohol. A voluminous, liglit-coloureil, amorphous precipitate was
tluis produced, which was collected, washed with a little alcohol, and
dried, when it amounted to 1*5 grams. The product was readily
soluble in cold water, and, although containing a large proportion of
inorganic material, rapidly hydrolysed yS-glucosides.

Extraction of the Fruit with Alcohol.

For the purpose of a complete examination, 27 kilograms of the
fruit were employed.

With consideration of the statement by Berg {loc. cit.) that the
elaterin contained in the fruit of Echallium exists in the form of a
glucoside which is readily hydrolysed by the enzyme present, the
material was treated in such a manner at to preclude the possibility of
any hydrolysis of its constituents taking place. E ich fruit, therefore^
was separately cut into several pieces, which were allowed to fall
directly into strong alcohol, the total volume of the latter having
been about 80 litres. After a short time, the mixture was heated to
the boiling point, and kept at this temperature for about fifteen minutes.
The whole was subsequently kept overnight, after which the marc was
removed by filtration, the liquid thus obtained being then found to
contain slightly over 75 per cent, by volume of alcohol.

The marc, separated by filtration as above described, was pressed,
and the liquid thus obtained was added to the main portion of alcoholic
extract. The seeds were then separated so far as possible from the
pressed marc, and the latter completely extracted in a Soxhlet apparatus
with hot alcohol, this extract being likewise added to that first
obtained. The united liquids were then concentrated by distillation
from a water-bath until alcohol ceased to pass over.

During the concentration of the alcoholic extract, as above described,
there separated a quantity of green resin (A), which was collected on
a filter and repeatedly treated with water until nothing further was
removed. The filtrate and washings from this resin were united, and
concentrated under diminished pressure to a volume of about 3 litres.
During this operation a quantity of light brown, resinous material (B)
separated, which was collected and thoroughly washed with cold water
the washings being added to the aqueous liquid (C).

Examination of the Green Resin (A).
This product was a dark green, soft mass, and amounted to 45 5
grams. It was dissolved in alcohol, and mixed with purified sawdust,
the thoroughly-dried mixture being then successively extracted in a
Soxhlet apparatus with light petroleum (b. p. 35 — 50''), ether,
chloroform, and alcohol.

THE FRUIT OF EOBArj.irM ELATKRIUM. 1 HST

Petroleum Extract of the Green Resin.

This extract was a dark green, viscid liquid, and amounted to 38
grams. It was dissolved in ether, the ethereal liquid being shaken
successively with solutions of sodium carbonate and sodivam hydroxide,
but nothing was thus removed. The ether was then evaporated, and
the residue hydrolysed by heating with an alcoholic solution of
potassium hydroxide, after which the alcohol was removed, water
added, and the alkaline solution of potassium saUs extracted with
ether. The ethereal liquid was washed, dried, and the solvent removed,
when a small quantity of a light browo, crystalline product was
obtained. This was dissolved in about 150 c.c. of hot absolute alcohfd,
and the solution kept for some time, when a nearly colourless sub-
stance separated. The latter was collected, washed with cold alcohol,
and then distilled under 15 mm. pressure. The distillate, which rapidly
solidified, was crystallised from ethyl acetate, when small, colourless,
glistening leaflets, melting at 68'^, were obtained. This substance was
a hydrocarbon, and appeared to be heatriacontane, C.^jH^p but the
amount was too small for analysis.

Isolation of a Phytosterol, C27Hj,,p.

The alcoholic solution from which the hydrocarbon had been
removed by filtration, as above described, was concentrated to a small
volume and diluted with water, when a quantity of crystalline sub-
stance separated. This was collected on a filter, and washed with a
little ethyl acetate, after which it was distilled under diminished
pressure. The distillate, which solidified on cooling, was crystallised
from a mixture of ethyl acetate and dilute alcohol, when it formed
colourless, glistening leaflets melting at 148'\ The amount of sub.stance
so obtained was 0 7 gram :

0-2806, heated at 115", lost 0-0134 H2O. H20 = 4-8.
0-1342 of anhydrous substance gave 0-4125 COg and 01430 H.A
0 = 83-8; H = ll-8.

CgyH^flOjH^O requires H20 = 4-5 per cent.

C.27H^gO requires 0 = 83-9; H = 1 1 -9 per cent.

The substance thus agrees in composition with a phytosterol, and it
yielded the colour reactions of this class of compounds. A determina-
tion of its specific rotatory power gave the following result:

0-205-), made up to 20 c.c. with chloroform, gave a^ -f- 0°4' in a 2-dcm.
tube, whence [a]D-f3-2°.

The acetyl derivative, when crystallised from acetic anhydride,
separated in flat, glistening needles, melting at 155 — 157°.

1!)S8 FOWEK ANJ) MOORE: 'I'llE CONSTITUENTS OF

The above-described phytosterol differs appreciably in some of its
characters from the commonly-occurring substances of this class, as
indicated, for example, by its higher melting point, its dextrorotation,
and the fact that the acetyl derivative melts higher than the substance
from which it was prepared.

The aqueous alkaline solution of potassium salts from which the
hydrocarbon and phytosterol had been removed by extraction with
ether, as above described, was acidified, and again extracted with ether.
The ethereal liquid obtained in this way contained a small amount of
a nearly colourless, very sparingly soluble substance in suspension.
This was collected on a filter, washed with ether, and crystallised from
pyridine, when it formed small, glistening plates, melting at
258 — 260°. It appears to be related to ipuranol, 023^330.2(0 FI)2, as
it gives the characteristic colour reactions of this substance, but the
amount obtained was insufficient for analysis (compare Amer. J.
rhann., 1908, 80, 264, 57G ; Trans., 1908, 93, 907 ; this vol., p. 249).

Examination of the Fatty Acids.

The ethereal liquid, from which the above-described substance had
been separated, was washed, dried, and the solvent removed. A
quantity (12 grams) of fatty acids was thus obtained, which, when
distilled under diminit>hed pressure, passed over between 230 — 235°/
10 mm. Eight grams of the mixed acids were converted into their lead
salts, and the latter digested with ether, when the larger portion was
dissolved. Both the soluble and insoluble portions were decomposed
by hydrochloric acid, and the regenerated fatty acids purified by
distillation under diminished pressure. The soluble portion of the
lead salts yielded 6 grams of liquid acids, whilst the insoluble portion
gave 15 grams of solid acids.

The Liquid Acids. — These acids when distilled under diminished
pressure passed over between 232° and 235°/15 mm.

An analysis and a determination of the iodine and neutralisation
values gave the following results :

0 13G6 gave 0-3860 OO2 and 0-1370 H2O. 0 = 77-1; H = 1M.

0-4095 ab.sorbed 0-8473 iodine. Iodine value = 206-9.

M120 neutralised 0-2211 KOH. Neutralisation value = 197-4.
CigHggOg requires 0 = 77*1 ; H = ll-4 per cent. Iodine value =181-4;

Neutralisation value = 200-4.

CigHgoOg requires 0 = 77-7 ; H = 10*8 per cent. Iodine value = 274-1 ;

Neutralisation value = 201-4.

These results indicated that the liquid acids consisted chiefly of a
mixture of linolic and linolenic acids, the former predominating.

THE FRUIT OF ECBALLIUM ELATERIUM. 1989

77/e Solid Acids. — These acids were crystallised from glacial acetic
acid, but no pure substance could be isolated by this means, the
product melting indefinitely between 54*^ and 58°.

An analysis and a determination of the neutralisation value gave
the following results :

01432 gave 0-3940 CO, and 0-1G31 H,0. C = 75-l ; H-12-6.
0-7500 neutralised 0-1559 KOH. Neutralisation value = 207-9.
CiijHg.^Oo requires 0 = 750; H = 12-5 per cent. Neutralisation

value = 219-l.
CjjHgijOo requires C = 76-l; H=12'7 per cent. Neutralisation

value =197-7.

The jiliove results indicated that the solid acids consisted of a
mixture of palmitic and stearic acids in about equal proportions.

Ethereal Extract of the Green Resin. Isolation of " Elaterin."

This extract amounted to about 6 grams. A portion of it (about
2 grams) was readily soluble in ether, and consisted of a dark-coloured
resin, whilst the remainder (4 grams) was a sparingly soluble,
crystalline powder. From the resinous product nothing definite
could be isolated, and as it yielded no sugar on boiling with a dilute
solution of sulphuric acid in aqueous alcohol, it was not glucosidic.

The above-mentioned, crystalline powder was collected on a filter,
washed with ether, and recrystallised from a small volume of absolute
alcohol, when it was obtained in small, colourless, hexagonal prisms,
melting and decomposing at 210 — 215°. On subjecting this product
to fractional crystallisation from absolute alcohol, three pHncipal
fractions were obtained. Although a complete separation could not
be effected by this means, owing to the limited quantity of material
at disposal, the three fractions, nevertheless, exhibited very marked
differences, as indicated especially by their solubilities, melting points,
and optical rotatoi'y power.

Fraction I. — This fraction formed small, colourless, hexagonal
prisms, melting and decomposing at 230°. It was very sparingly
soluble in alcohol, and amounted to 0-7 gram :

0*2554, made up to 20 c.c. with chloroform, gave a^ - 1°21' in a
2-dcm. tube, whence [a]o -52-4°.

Fraction II. — This fraction closely resembled fraction I in appear-
ance. It was, however, more soluble in alcohol, and melted, with
decomposition, at about 210°. It amounted to 15 grams.

02245, made up to 20 c.c. with chloroform, gave a^ - 0°48' in a
2-dcm. tube, whence [ajo -35-6°.

Fraction III. — This fraction cry.<itallised in small, colourless plates,

liMlO rowKR Axn mooue : the constituents of

melting and decomposing at 189 — 190°. It was very soluble in alcohol,
and amounted to only 025 gram :

0-2346, made up to 20 c.c. with chloroform, gave a„ + ^24' in a
2-dcm. tube, whence [a]u +17'0°.

The three fractions gave on analysis the following remits :
I. 0 1607 gave 0-4056 COg and 01180 HS>- C = 68-9; H = 8-l.
TI. 0-1468 „ 0-3710 CO., „ 0-1114 H^O. C = 68-9 ; H = 8-4.
III. 01355 „ 0-3406 CO2 „ 0-1005 H2O. C = 686 ; H = 8-2.
<^2o"H'oA requires C = 68-9 ; H = 80 per cent.
C^.H^'^O, „ C = 68-9 ;H = 8-0
CggH^sOy „ 0 = 69-1 ; H = 7-8

From these results it is evident that the above-described, sparingly
soluble, crystalline powder correfponds to the product known as
" elaterin," and which is recognised under this title by the British and
United States Pharmacopoeias. The formulje which have been
assigned to elaterin by various investigators are as follows : CopH^gOr,,
Zwenger (Annalen, 1842, 43, 460) ; Oo4H3^0,,. Hemmelmayr (Ber.,
1906, 39, 3380); OosHggO-, Berg (Bull. "Soc. chim., 1897, [iii], 17,85;
1906, [iii], 35, 435). It has, however, quite recently been shown by
the present authors (Pharm. J., 1909, [iv], 29, 501) that the product
known as elaterin is not homogeneous, as has hitherto been assumed,
but that it consists of a mixture of substances which, although
possessing apparently the same percentage composition, differ
essentially in their physical properties, especially in their optical
rotatory power, as also in their physiological action. The above-noted
results of the present investigation therefore afford further confirmation
of the previous conclusions.

The final alcoholic mother liquors obtained during the separation
of the above-described elaterin fractions yielded, on dilution with
water, a small amount of a colourless substance, which crystallised in
small needles and melted and decomposed at 168 — 170°:

0-2098, heated at 115°, lost 0-0070 H.O. H.O^S.S.
0-1318 of anhydrous substance gave 0-3264' OOg and 0-0980 H2O.
0 = 67-5; H = 8-2.

A. determination of its specific rotatory power gave the following
result :

02942 of anhydrous substance, made up to 20 c.c, with chloroform,
gave oo -f-0°38' in a 2-dcm. tube, whence [ajn -t-21-5°.

These results would indicate that the above-described substance
consisted to a considerable extent of the dextrorotatory constituent
of elaterin, but the amount of material available was fo small that it
was impossible to obtain any evidence of its purity.

TTTE FRUIT OF EORALLTTTM ELATFTtlTTM. 1001

Inasmuch as wo have shown that the pi'oduct known as elateiin
consists of two substances of apparently the same percentage com-
position, one of which is laevorotatory and devoid of physiological
activity, whilst the othei* is dextrorotatoiy and possesses an intensely
purgative action, it seems desirable that the respective substances
should be designated by distinctive names. It is therefore proposed
to designate the chief constituent of crude elaterin, which is lajvo-
rotatory, as a-elaterin, and the dextrorotatory, physiologically active
constituent, as (S-elixterin. •

Chloroform and Alcohol Eo'tracts of the Green Resin.

Both of these extracts consisted of brown, resinous material, and
they amounted toO'3 and 0*5 gram respectively. As nothing definite
could be isolated from them, they were united, and boiled for some
hours with a dilute solution of sulphuric acid in aqueous alcohol. No
sugar was formed by this treatment, and the extracts, therefore, were
evidently not glucosidic.

Examination of the Brown Resin (B).

This was a light bi-own powder, and amounted to 6 "5 grams. It was
dissolved in alcohol, and mixed with purified sawdust, the thoroughly
dried mixture being then successively extracted in a Soxhiet apparatus
with ether, chloroform, and alcohol. The ether removed about 5*5
grams of material, from which, with the exception of small amounts of
elaterin, nothing definite could be isolated. The chloroform and alcohol
extracts amounted to only 0"2 and 0'5 gram respectively, and consisted
of brown resins. Nothing of a glucosidic nature was contained in any
of these extracts.

Examination oftJie Aqueous Liquid (C).

This liquid, as already indicated, represented that portion of the
original alcoholic extract of the Echallium fruits which was soluble in
cold water, and from which the previously-described resins (A) and
(B) had been separated. It was extracted many times with ether, the
combined ethereal liquids being washed, dried, and the solvent
removed, but only a small amount of an indefinite, amorphous product
was thus obtained.

The aqueous liquid, after extraction with ether, was shaken with
successive portions of amyl alcohol, the combined extracts being
washed, and the solvent removed by distillation under diminished
pressure. A quantity (about 15 grams) of resinous material was thus
obtained, which was only sparingly soluble in water. As nothing

1992 (^OXSTITUF.XTS OF TTIE FRUIT OF FCB.VLLIUM ELATERIUM.

definite could be isolated from it, it was boiled for some hours with
dilute alcohol containing 3 per cent, of its weight of sulphuric acid.
The chief product of this operation was, however, entirely resinous,
and, as no sugar was formed, it was evident that the material contained
nothing glucosidic.

After extraction with amyl alcohol, as above described, the aqueous
liquid was concentrated, and treated with a large volume of strong
alcohol. This precipitated a quantity of inorganic material, consisting
chiefly of potassium chloride and sulpbate, together with a sugar
which yielded rf-phenylglucosazone, melting at 216". The clear liquid
was then decanted and the alcohol removed, when a small quantity of
a syrup was obtained. This was dissolved in a small quantity of
water and kept for several days, but nothing separated. The solution
was then diluted with water, and, after adding 5 per cent, of its
weight of sulphuric acid, the whole was boiled for several hours. The
only products resulting from this treatment that could be identified
were a little formic acid and furfuraldehyde.

Summary.

The results of the pi'esent investigation of the fruit of Echrdlium
Elaieriitm may be summarised as follows :

In accordance with the previous observation of Berg {Bull. Soc.
cimn., 1897, [iii], 17, 85), the fruit was found to contain a small
amount of an enzyme which is capable of hydrolysing /S-glucosides.

The liquid obtained by the extraction of 27 kilograms of the fresh
fruit with alcohol yielded, on concentration, a quantity (45-5 grams) of
a green resin, and, by the further evaporation of the liquid, 6'5 grams
of brown, resinous material were separated. The green resin, when
extracted with various solvents, yielded a very small amount of
a hydrocarbon (m. p. 68°), which was probably hentriacontane, Cg^H^^^;
a phytosterol, Cg^H^gO (m. p. 148°; [a]f, +3*2°) ; a substance melting
at 258 — 260°, which appears to be related toipuranol, C23Hgg02(OH)2 ;
a mixture of fatty acids ; and a product corresponding to the
so-called " elaterin," the characters of which have previously been
elucidated by the authors (Pharm. J., 1909, [iv], 29, 501). It is now
proposed to designate the Isevorotatory constituent of crude elaterin as
a-elaterin, and the dextrorotatory, physiologically active constituent
as /S-elaterin. From the brown, resinous material, with the exception
of small amounts of elaterin, nothing definite could be isolated. The
portion of the alcoholic extract of the fruit which was soluble in water
contained a considerable amount of inorganic salts, consisting chiefly of
potassium chloride and sulphate, and a sugar which yielded (Z-phenyl-
glucosazone (m. p. 216°).

RESOLUTION OF PHOSPHORIC ACID DERIVATIVES. 1993

No evidence could be obtained of the presence of a glucoside of
elaterin, which has been stated by Berg {loc. cit.) to be contained in
the juice of the fresh fruit, nor could any other glucosidic sub>tance
be detected. It was, on the other hand, quite definitely ascertained
that the so-called "elaterin" exists in the fruit aa such and not in a
combined state. The various amorphous products which were described
many years ago by Walz (y. Jahrb. Pkarm., 1859, 11, 21, 178) under
the names of prophetin, ecbalin or elateric acid, hydroelaterin, and
elateride were evidently indefinite mixtures, and are therefore entitled
to no further consideration in chemical literature.

The Wellcome Chemical Reseauch Labouatoiues,
London, E.G.

CCXIX. — The Resolution, of Asymmetrical Derivatives
of Phos2^horic Acid.

By Beknaiid Dunstan Wilkinson Luff (1851 Exhibition Scliolar)
and Fi^EDEKic Stanley Kipping.

In the case of all tlie optically active compounds wliicli are known
at the jDresent time, with the exception of methyk-yf/ohexylidene-
acetic acid (Perkin, Pope, and Wallach, this vol., p. 1789), and
jDossibly with the further exception referred to below, the optical
activity is due to the presence of one or more fully saturated
asymmetric groups. To the best of our knowledge there is no
recorded instance in Avhich optical activity is conditioned by the
presence in the molecule of an unsaturated asymmetric complex,
such as one of those represented by the following symbols :

ttv yh ftv yb

X X •

The 2>ossible exception is that afforded by the work of Meisen-
heimer, who has shown (Ber., 1908, 41, 3966) that methylethyl-
aniline oxide may be resolved into enantiomorphously related com-
ponents, which are optically active in solution. Bvit, as Meisen-
heimer himself points out, the base in solution may be either the
oxide or the hydroxide, represented resjDectively by the formulae :

C^H.v C,H,\ /OH

CfiHg^NIO and C,5H.-^N<
CHg/ CH3/ ^OH

1994 LUFF AND KIPPING : THE RESOLUTION OF

Consequently, as it is not yet known which of these forms is
actually present, the possible existence of optically active compounds
of the unsaturated type indicated above is left an open question.
Long before the publication of Meisenheimer's results, attempts
were made in these laboratories to prepare an unsaturated asym-
metric phosphoi'us compound of the type PORjRoRs, and then to
resolve it into its optically active components. The first 6i these
tasks was, in fact, successfully accomplished several years ago by
Caven (Trans., 1902, 81, 1362), who obtained aniliuo-^j-toluidino-
phosphoric acid, PO(NHPh)(NH-CoH^Me)-OH, methoxy-2>
toluidiuophosphoric acid, PO(Nri-C«H^Me)(OMe)-OH, and other
asymmetric compounds from phosphoryl chloride; on the other
hand, the few experiments on the resolution of these acids which
were made at that time on a very small scale by one of us gave
only negative results.

As the further investigation of this matter seemed to be of some
importance, anilino-^J-toluidinophosphoric acid was prepared by the
method described by Caven (Joe. c'lt.), and its cinchonidine,
strychnine, and quinine salts were submitted to fractional crystall-
isation ; in all three cases negative results only were obtained. The
experiments with salts of this acid, however, were not continued
beyond this stage, firstly because of the relative instability of the
acid, and secondly because, as already pointed out by Caven {loc.
cit.), there is, theoretically, a possibility of the occurrence of
tautomeric or isodynamic change in the molecule of an acid of
this type, whether it is in the free state or in combination with a
base.

In the case of the acid, the hydroxylic hydrogen atom might
simply wander from one oxygen atom to the other, or a similar
end result might be reached by the more complex changes indicated
in the following scheme :

NHR\^ yNHR' NHRv ^NR' NHRx /NHR'

P ^-^ P ^-^ P

If either of these processes occurred, the existence of an optically
active acid of this type in the free state would, of course, be
impossible.

In the case of the salts of the acid, even assuming that hydrolysis
did not occur, intramolecular change in the grouping

/NHR
might still take place. xVs a result of such a molecular rearrange-

ASVMMErKICAL DEIUVATIVLS OF PHOSPHORIC ACID. 1995

merit, it is not inconceivable that on crystallising a salt of anilino-
/(-toluidinophosphoric acid which contained an active base, all the
acid molecules might be transformed into o7ie of the optically active
forms, namely, that which gave the more sparingly soluble salt.
A resolution or transformation of this character, provided that it
occurred sufficiently rapidly, would not be detected unless the
specific rotation of the salt in aqueous solution could be determined,
and the observed behaviour of the salt would simulate that of a
non-resolvable partially racemic substance. In view of these possi-
bilities, it seemed better to prepare some asymmetric substituted
phosphoric acid in which the possibility of tautomeric or isodynamic
change was excluded, or, at any rate, was very remote. Conse-
quently, attempts were made to obtain methoxymethylanilino-
phosphoric acid and cthoxymethylanilinophosphoric acid, but with-
out success.

The preparation of phcnyl-j^-tolylphosphoric acid,
PO(OPh)(0-CoH4Me)-OH,
was then undertaken, and was accomplished without difficulty by
treating phenylphosphoryl chloride with sodium ^^tolyloxide and
decomposing the phenyl-^^-tolylphosj^horyl chloride with water.
This acid, in the form of its salts, is fairly stable towards water,
and in the hope of resolving it into its optically active components
many of its salts containing an active base were submitted to
fractional crystallisatiom from various solvents; after systematic
treatment, the extreme fractions were collected, and their melting
points were determined as well as their specific rotations in methyl-
alcoholic solution.*

The following table contains a summary of the results thus
obtained :

Salts of r/ienyl-p-toli/lphosphoric Acid, PO(OPh)(0-C6H4Me)-OH.

" Most sparingly "Least sparingly

soluble" fraction. soluble" fraction.

A A

Salt. M. p. [ajo. M. p. [a]y.

Ciuchouidine 195—196° -77-3" 191—195'^ -750°

Quinine 170 -120-6 168—169 -121-1

Z-Menthylamine 198—200 -16-0 198—200 -15-4

Strychnine 149-150 -lO'l 149—150 -11-2

Brucine 168—169 -6-1 167—168 -64

Cinchonine 194—195 -I-120-9 194—195 4-121-3

(Z-Methylhydrindamine 135—137 4-16-9 132—134 4-16-5

fZ-Hydrindamine 12S— 129 — 128—129 —

It will be seen from these data that in no case was there any
evidence whatever of a resolution having occurred ; all the fractions

* All the specific rotations given in this paper were determined in 98 per cent,
methyl-alcoholic solution.

19!)6 LUFF AND KIPPINO : THE RESOLUTION OF

of a given compoiind ;i])pearcd to be homogeneous, and were
identical in melting point and specific rotation within the limits
of experimental error.

Now there seem to be no reasonable grounds for attributing
these negative results to the occurrence of tautomeric or isodynamic
change. It is not impossible, of course, that in aqueous and
related solvents the salts may be partially hydrolysed, and that the
free acid may then undergo isomeric change; if this were so the
consequences might be similar to those discussed in the case of the
amino-acids, that is to say, the whole of the deposited salt might
be derived from one of the active acids without there being any
evidence that such was the fact. But fractional crystallisation of
some of the above salts from ethyl acetate, ether, and other non-
hydrolysing liquids gives the same negative result as that obtained
with the use of aqueous alcohol; hydrolysis, followed by intra-
molecular change in the acid, seems therefore to be excluded as
a possible explanation of the observations.

It has been shown by Kipping and Hall (Trans., 1901, 79, 444)
that, in accordance with theoretical considerations, an externally
compensated acid chloride, such as f7^phenylchloroacetyl chloride,
gives, with an externally comi^ensated base, such as (7/-hydrindamine,
two isomeric amides; these isomerides are themselves externally
compensated, and if A represents the acid, and B the basic nucleus,
the one is a mixture or racemic compound* of dBdA and IBIA, the
other a mixture or racemic compound of dBlA and IBdA.

As the result of the examination of many salts of phenyl-2?-tolyl-
phosphoric acid failed to give any indication of the asymmetry of
the acid molecule, it seemed advisable, before going further, to
obtain, if possible, some evidence of this asymmetry by the appli-
cation of the method just described.

For this purpose, phen3'l-p-tolylphosphoryl chloride was treated
with r/Z-hydrindamine in ethereal solution, and the product was
examined. Its whole behaviour showed at once that it was a
mixture; it could hardly be recrystallised without this fact
becoming noticeable, and from it, in the first place, a crystalline
compound melting at 98 — 100° was isolated without very much
difficulty. After jDrotracted crystallisation, there was obtained a
second compound, melting at 85 — 87°, but which was doubtless
not quite free from the substance of higher melting point.
Analyses and a careful examination of these two products
showed that they were isomeric hydrindamides of the formula
PO(OPh)(0-C6H4Me)-NII-C9H9; and that the compound cf lower
melting point was, in fact, a distinct substance, and not merely

ASYMMETRICAL DERIVATIVES OF PFIOSPHORIC ACID, 1997

an impure form of the amide of higher melting point, was con-
clusively established.

The result of the experiment made with f//-hydrindaniine rendered
it probable that the acid was a mixture of enantiomorphously
related isomerides, and that, by employing one of the active bases,
these isomerides, in the form of their hydrindamides, might be
separated from one another. Such a resolution would be strictly
comparable to that which may be brought about by fractionally
crystallising the amide formed from a dl-hase and an optically
active acid (Kipping and Salway, Trans., 1904, 85, 438).

The (^-hydrindamide of phenyl-2J-tolylphosphoric acid, therefore,
was prepared ; in this case, also, the product was obviously a mixture,
and when fractionally crystallised it yielded two isomeric sub-
stances.

The more sparingly soluble or a-compound melted at 127°, and
had [a]j) — 17'4°; the )8-isomeride, which no doubt contained some
of the a-compound, melted at 82 — 86°, and had [a]j^ — 21'2°.
Although the difference in value between the specific rotations of
the two isomerides is not large, the fact that the more readily
soluble )8-compound has the higher rotation is important evidence
that the latter is not simply the impure a-derivative, the absence
of rZ-hydrindamine salt in the samples having, of course, been
proved very carefully.

As a confirmatory experiment, the ^menthylamide of the acid
was prepared, and the product was submitted to fractional crystall-
isation. Here again the more sparingly soluble or a-isomeride
was separated in a pure state without any great difficulty ; it
melted at 110°, and had [o]p — 32"3°. The /3-isomeride, obtained
from the mother liquors, and probably not quite free from the
o-compound, melted at 85 — 86°, and had [a]p — 37"9°.

The fact that the acid is so easily resolved into two compounds
by the fractional crystallisation of the amides which it forms with
active bases is in strange contrast to the behaviour which it shows
when it is combined as the salt of an active base. On comparing
the structures of the two classes of compounds, it would seem that
isomeric change of a recognised common type might occur much

.NHR
more easily in the case of the amides, ^Pvx > than in that of

^0

the salts, >p/
^O

But, since the amides are quite stable and may be repeatedly
crystallised without their undergoing any alteration in properties,

VOL. XCV. 0 Q

199S LUFF AND KIPPING : THE RESOLUTION OF

it seems reasonable to couelude that the occurrence of intra-
molecular rearrangement has nothing to do with the failure to
resolve the acid by crystallising its salts with active bases.

From the results of this investigation, it also seems clear that
phenyl-7;-tolylphosphoric acid is a mixture of enantiomorphously
related isomerides, and that the unsaturated grouping (I) is com-
parable with the saturated complex (II) :

% / "\ /'

P C

(I.) (II.)

tJnfortunately, although the optically active components of the
acid have in all probably been separated from one another, their
preparation in the free state was not practicable, owing to the
stability of the amides in which they were contained.

Experimental.

Anilino-p-toluidinophosphoric acid,

PO(NHPh)(NH-CoH4Me)'OH,
was prepared by the method described by Caven (Trans., 1902, 81,
1369), and was purified by dissolving it in 50 per cent, alcohol
containing ammonia, and then acidifying the solution with hydro-
chloric acid. The compound is thus obtained in pearly leaflets,
and there is less decomposition than when aqueous alcohol or
acetone alone is employed as solvent.

Strychnint A nilino-'p-toluidino'pJiosphate.

This salt was precipitated in crystals on adding a solution of
strychnine hydrochloride to a solution of the ammonium salt of the
acid. It was washed with water and fractionally crystallised from
cold aqueous methyl alcohol, from which solvent it was deposited
in glistening needles. After about twelve crystallisations, extreme
fractions were examined ; the specific rotations were determined
in methyl-alcoholic solution.*

"Most Hijarinfjly soluble" fractio7i.~M. p. 137—138°. 1349
(dried at 100°), made up to 25 c.c, gave, in a 2-dcm. tube, a-071°,
whence [a]n-7-3°.

"Least spur'uKjly soluble" fraction. — M. p. 137 — 138°. 0-69
Cdried at 100°), made up to 20 c.c, gave, in a 2-dcm. tube, o-0-49°,
whence [a\^-'^'l°.

The salt crystallises from aqueous solvents in prismatic needles,
* See footuote on p. 1995.

I

ASYMMETRICAL DERIVATIVES OF PHOSPIIO|{lC ACID. 1999

and is readily soluble in acetone, chloroform, and the common
alcohols, but is only sparingly soluble in benzene and almost
insoluble in light petroleum. On repeatedly crystallising the salt
from aqueous alcohol, slight decomposition occurred, so that the
final mother liquors, -which were brown and had an odour of
2;-toluidine, were discarded in the above operations.

Cinchunidine Aiiilino-ii-toluufinaj'^iosphalc.

This compound was obtained as a crystalline precipitate on the
addition of cinchonidine hydrochloride to a solution of the
ammonium salt; after one crystallisation from aqueous methyl
alcohol, it melted at 203°, but after one Or two more recrystal-
lisations the melting point fell to 199°. This was due to hydrolysis
brought about by the prolonged heating with the solvent which
was necessary to redissolve the salt.

As the compound was insoluble in non-hydrolysing solvents such
as benzene, its investigation was not continued.

Q u inin e A n illn o-p-tolu Id'ui oj)h ospha te.

This salt was precipitated as a solid on adding a Solution of
quinine hydrochloride to a solution of the ammonium salt of the
acid. It was washed and dried, and dissolved in a mixture of hot
benzene and light petroleum containing a little methyl alcohol;
from this mixture it was deposited in crystals melting at 155 — 156°,
but after it had been separated into several fractions as the result
of three or four similar recrystallisations, the melting point ranged
from 160° to 175°; this result seemed to be due to the employment
of a larger proportion of methyl alcohol in the solvent, for, when
these fractions were recrystallised from benzene and petroleum
containing only a trace of methyl alcohol, the melting point fell
again to 155 — 156°. It was also found that when the solid melting
at 155 — 156° was warmed on the water-bath with benzene, the
melting point gradually rose to 180 — 181°; the same result was
obtained by crystallising a portion of the salt melting at 155 — 156°
from aqueous methyl alcohol, the lustrous prisms thus obtained
melting at 180 — 181°. A mixture of the samples melting at
155 — 156° and 180—181° respectively liquefied at about 175°.
Further, on dissolving some of the salt melting at 180 — 181° in
cold chloroform, and then adding light petroleum, there was pre-
cipitated an oil which set to a glassy solid ; the latter, when heated
slowly, swelled up to a frothy mass at 80 — 100°, and seemed to
melt at about 130°, properties which it retained even when kept
during some days.

6 Q 2

2000 LUFF AND KIPPING: THE RESOLUTION OF

It seems from these observations that the quinine salt exists in
three modifications, which are easily converted one into the other
by recrystallisation, but the matter was not further investigated.

Determinations of the specific rotations of the samples melting
at ISO — 181° and 155 — 156° respectively confirmed the conclusion
that the different melting points observed were not due to a
resolution of the acid having occurred:

Salt melting at 180 — 181°. — 0-7398, made up to 25 c.c, gave, in
a 2-dcm. tube, a -7-76°, whence [aj^- 131-0°.

Salt melting at 155 — 156°. — 0-7114, under the same conditions,
gaveo-7-39°, whence [a]^-Vl'^-d>°.

E xperinients on the Prejiaration of an Alkyloxyrmthylanilino-
jphosjihoryl Chloride.

An attempt was made to prepare methoxymethylanilinophosphoryl
chloride, PO(OMe)(NMePh)Cl, by treating methoxyphosphoryl
chloride (1 mol.) with methylaniline (2 mols.) in benzene solution;
no immediate jjrecipitation of methylaniline hydrochloride occurred,
but in the course of half an hour crystals began to separate. After
the mixture had remained overnight, the solution was filtered and
evaporated, when a viscid, oily liquid remained. Similar experi-
ments, using ether or light petroleum as solvent, gave similar
results, but it was found to be impossible to isolate any crystalline
substance from the crude oily product; attempts to prepare the
corresponding ethoxy-derivative were also unsuccessful.

Phenyl-^-tolylfhos'phoryl Chloride, P0(0Ph)(0-C6HiMe)Cl.

A thin paste of sodium 2>tolyloxide (1 mol.) and ether, prepared
by treating an ethereal solution of 2>cresol with sodium wire, was
slowly run into an ethereal solution of phenylphosphoryl chloride
(1 mol.), the whole being well stirred during the operation. The
reaction took place immediately, sodium chloride being deposited
in a microcrystalline form. After some time the solution was
filtered in absence of moisture ; the ether was then evaporated, and
the residue submitted to fractional distillation under 35 mm.
pressure. Fractions were first collected boiling at (I.) below 235°,
(II) 235—255°, and (III) 255—275°, and during this first distil-
lation sodium chloride separated in moderate amount. After
further systematic operations, a large proportion of liquid boiling
at 244 — 248°/35 mm. was obtained.

An analysis of this fraction gave the following result :

0-643 gave 0317 AgCl. €1=121.

CijHigOvClP requires CI = 12-5 per cent.

ASYMMETRICAL DERIVATIVES OF PHOSPHORIC ACID. 2001

Phenyl-Tp-tolyl'phos'pJioryl cJiloride is a colourless, highly refractive
liquid, which does not fume in moist air until it has been exposed
for some time ; it is only slowly acted on by cold water, giving
the corresponding acid, but it is readily converted into the sodium
salt of the acid when it is warmed with dilute sodium hydroxide
solution.

Phenyl-^-toly!phosp7ioric Acid, P0(0Ph)(0-CcH4Me)'0H.

The chloride was placed in a stoppered bottle with an excess of
10 per cent, sodium hydroxide solution, and the contents were then
warmed to about 60° and shaken vigorously. In a short time the
chloride passed into solution, and, on acidifying, an oil was
deposited ; the supernatant liquid was then decanted, and the oil,
after having been washed with water, was dried over sulphuric
acid. In the course of a few days it solidified, and was then
purified by crystallisation from a mixture of benzene and light
petroleum; the acid was thus obtained in tufts of radiated, wax-
like needles, melting at 54°. On analysis :

0-1706 gave 0-3692 CO., and 00772 H^O. C = 59-0; H = 5-0.
CjsHjsO^P requires C = 59-l ; H = 4-9 per cent.

The equivalent of the acid was determined by means of standard
barium hydroxide sokition ; this gave a value of 262, the calculated
equivalent of phenyl-^^-tolylphosphoric acid being 264.

The acid is nearly insoluble in water and in light petroleum,
but is soluble in chloroform, benzene, and the common alcohols ;
it is not readily hydrolysed by alkalis, prolonged boiling being
necessary. In subsequent preparations of the acid, the pure
chloride was not isolated, but tlie crude product obtained by the
interaction of the phenylphosphoryl chloride and sodium 2?-tolyl-
oxide, after evaporating the ether, was treated as follows.

The residue was washed into a stoppered bottle with 10 per
cent, sodium hydroxide solution, and the mixture warmed to about
60°; the whole was then violently shaken, and after a few minutes
the oil had almost completely passed into solution, only a small
proportion remaining undissolved. As the liquid cooled, this
insoluble oil solidified, and was then separated ; it is described later.

The clear alkaline solution was treated with excess of hydro-
chloric acid, whereupon the phenyl-p-tolylphosphoric acid was pre-
cipitated as an oil ; after having been washed and dried in a vacuum
desiccator, it solidified to a crystalline mass, melting at 53°.

2002 LUFF AND KIPPINC. : JHE RESOLUTION OF

I'hcnyl ni-xUoli/l Pho^ihatc, PO(0-C«H4Me)2-OPh.

This compound was formed in small quantities in the preparation
of phenvl-^j-tolylpliosplior}-! chloride, and remained as a solid when
samples of the impure chloride wore treated in the manner just
described; after crystallisation from light petroleum, it melted at
54°. An estimation of phosphorus was carried out by igniting a
mixture of the solid and sodium peroxide, and subsequently titrating
with standard uranium nitrate :

0"584 required 236 c.c. uranium nitrate (1 c.c. = 0'00209 gram P).
P = 8-4.

CooHjfiOjP requires P = 8'7 j)er cent.

The ester is soluble in the common alcohols, benzene, and light
petroleum, and crystallises in rectangular plates.

Cinchonidlne Phenyl ^-Tolyl Phosfhaie,

On the addition of cinchonidine hydrochloride to a solution of
the ammonium salt of the acid, a white, crystalline precipitate was
immediately obtained. The salt was separated by filtration, washed,
and fractionally crystallised from hot aqueous alcohol, from which
solvent it was deposited in long, silky needles. After about eight
recrystallisations, the extreme fractions were examined :

"Most sfaringly soluble" fraction.— U. p. 195—196°. 0-291
(dried at 100°), made up to 25 c.c, gave, in a 2-dcm. tube, a — r80°,
whence [a]jj — 77-3°.

" Least sparingly soluble " fraction. — M. p. 194 — 195°. 0*237,
under the same conditions, gave a — 1'42°, whence [a]p — 75"0°.

The salt is soluble in cold ethyl acetate, chloroform, acetone, and
the common alcohols, but is insoluble in light petroleum. A sample
of the salt was also fractionally crystallised from a hot mixture
of benzene and light petroleum, but the extreme fractions had the
same properties as when aqueous alcohol was used.

Quinine Phenyl i^-Tolyl Phosphate.

This salt was precipitated as an oil on adding a solution of
quinine hydrochloride to a solution of the ammonium salt, but it
soon solidified. A sample was fractionally crystallised from aqueous
alcohol, from which it separated in a somewhat flocculent form ;
extreme fractions obtained after about eight recrystallisations had
the same melting points and the same specific rotations.

" MoHt sparingly soluble " fraction. — M. p. 170°. 02446, made
up to 25 c.c, gave, in a 2-dcm. tube, a -2-36°, whence [0]^- 120-6°.

ASYMMETRICAL DKKI VATI VKS OK IMIoSPlloHIO ACID. 2003

" Least sparifif/Ii/ soltihlt " fraction. — M. p. 168 — 1G9°. 0'383,
under the same conditions, gave o — 3"77°, whence [ajp — 121'1°.

The quinine salt is deposited from both aqueous and dry solvents
in felted masses of microscopic needles; it is soluhle in cold ethyl
acetate, chloroform, and the common solvents, but is insoluble in
light petroleum. A sample of salt fractionally crystallised from
a mixture of chloroform and light petroleum gave the sam.c results
as those obtained by employing aqueous alcohol as solvent.

\-MentJiylamine PJienyl ^-Tnhjl FJiosjihate.

The oily salt, prepared by precipitation, did not solidify for some
time. It was washed with water and fractionally crystallised from
aqueous alcohol at the ordinary temperature, the process being
continviod until the "most sparingly soluble" portion had been
crystallised eight times. The two extreme fractions were then
examined, but the results showed that a resolution had not
occurred :

"Most sfaringly soluhle" fraction.— M. p. 198—200°. 0-1064,
made up to 20 c.c, gave, in a 2-dcm. tube, a-0'17°, whence
[ajp-16-0°.

" Least sparingly soluhle " fraction.— M.. p. 198—200°. 0-1426,
under the same conditions, gave a — 0'22°, whence [a]p — 15"4°.

The salt crystallises from aqueous alcohol in long, silky needles;
it is soluble in nearly all organic solvents, such as benzene, light
petroleum, and ethyl acetate, even in the cold.

Strychnine Phenyl ^t-Tolyl Phosphate.

This salt was systematically crystallised from aqueous alcohol at
the ordinary temperature, and extreme fractions were then
examined :

"Most sparingly soluhle" fraction. — M. p. 150 — 151°. 0-335,
made up to 20 c.c, gave, in a 2-dcm. tube, o — 0-34°, whence

iMd-io-i°.

" Least sparingly soluhle " fraction. — M. p. 150 — 151°. 0-338,
under the same conditions, gave o — 0-34°, whence [a]i5-ll'2°.

The salt crystallises from aqueous solvents in rosettes of needles,
and is soluble in acetone, chloroform, or alcohol, but is insoluble in
light petroleum.

Brucine Phenyl p-Tolyl Phosphate.

On adding brucine hydrochloride solution to a solution of the
ammonium salt, an oil was first precipitated, which redissolved on

2004 LUFF AXn KIPPIXC: THE RESOLUTION OF

stirring; ou further addition of the hydrochloride, however, a
permanent, oily precipitate was obtained. The salt did not solidify,
even in the course of some days, but when washed with water and
evaporated with methyl alcohol it was obtained as a glassy mass.
The compound could not be obtained in crystals from aqueous
solvents, but from hot ethyl acetate, containing a little methyl
alcohol, it separated in prisms ; it was fractionally crystallised from
this mixture about eight times, and extreme fractions were then
examined :

"Most sparingly soluble" fraction.— M. p. 168—169°. 0-821,
made up to 20 c.c, gave, in a 2-dcm, tube, a-0'50°, whence
[a]„-6-l°.

" Least sparingly soluhle " fraction. — M. p. 167 — 168°. 0-894,
under the same conditions, gave a — 0'58°, whence [a]^ — 6-4°.

The brucine salt was obtained in another crystalline form by
keeping the oily precipitate for some weeks ; at the end of this time
it began to solidify, giving well-defined prisms. These contained
water of crystallisation, and, when anhydrous, melted at 116 — 118°;
on recrystallisation from ethyl acetate and methyl alcohol, however,
the compound melting at 168—169° w-as deposited.

The salt is soluble in chloroform, acetone, and the common
alcohols, but is insoluble in light petroleum, ethyl acetate, or
benzene.

Cinchonine Phenyl p-Tolyl Phosphate.

This salt remained oily during several hours, but after having
once solidified it crystallised readily from weak aqueous alcohol.
It was fractionally crystallised from this solvent, and after t-en
operations extreme fractions were collected and examined :

"Most sparingly soluble" fraction. — M. p. 194 — 195°. 0214,
made up to 25 c.c, gave, in a 2-dcm. tube, o-h2-07°, whence
[a]ij+ 120-9°.

"Least sparingly soluble" fraction. — M. p. 193 — 194°. 0*164,
under the same conditions, gave a +1-99°, whence [aj^-f- 121*3°.

The cinchonine salt crystallises in prismatic needles, and is soluble
in cold chloroform, acetone, benzene, and the common alcohols, but
is insoluble in light petroleum.

d-M ethylhydrindamine Phenyl Y>-Tolyl Phosphate.

The «Z-methylhydrindamine salt of phenyl-j;-tolylphosphoric acid
was prepared by fractionally precipitating a solution of the sodium
salt with the hydrochloride of the ri-base. The first separation did
not solidify for some time, but all later fractions, which were only

ASYMMETRICAL DERIVATIVES OF PHOSPHORIC ACID. 2005

precipitated after the first one had crystallised, solidified imme-
diately. Three main fractions were thus obtained ; they all melted
at 123 — 125° after having been recrystallised once from aqueous
methyl alcohol.

As fractional precipitation from aqueous solvents had given
negative results, the whole of the salt was washed and dried and
systematically crystallised from a mixture of ethyl acetate and ether.
The most sparingly soluble portion thus obtained, after about six
operations, melted at 135 — 137°, the most readily soluble one at
132 — 134°, but the two preparations gave the same specific
rotations :

"Most sparitigly solitble" fractio?i. — M. p. 135 — 137°. 0"467,
made up to 20 c.c, gave, in a 2-dcm. tube, a + 0'79°, whence
[a]^+16-9°.

" Least sparing!?/ soluble " fraction.— M. p. 132—134°. 0836,
under the same conditions, gave o + l'34°, whence [a]p+16'5°.

The whole of the salt was then fractionally crystallised from
anhydrous acetone about six times ; the most sparingly soluble
fraction melted at 135 — 137°, and when examined polarimetrically
gave the following result:

0'887, made up to 20 c.c, gave, in a 2-dcm. tube, o+ 149°, whence
Wd+16-8°.

The further examination of this salt showed that the different
melting points of preparations from aqueous methyl alcohol and
from ethyl acetate or acetone were not due to a resolution of the
acid having occurred ; although many experiments were made, the
conditions leading to the production of the different crystalline
forms were not very satisfactorily established. Sometimes the
crystals obtained from a mixture of ethyl acetate and ether melted
at 124 — 125°; sometimes they only sintered at this temperature
very slightly and then melted at 134 — 136°; occasionally they only
showed faint signs of sintering at 125°, and partially and suddenly
melted at 130—131°, the rest liquefying at 135—136°.

The salt is very readily soluble in methyl alcohol, and dissolves
freely in hot ethyl acetate or hot acetone, but it is only sparingly
soluble in ether, and practically insoluble in cold water.

d-Hydrind amine Phenyl -p-Tolyl Phosphate.

This salt was prepared from the sodium salt by precipitation, but
not in large quantities; it remained oily during several hours, but
after having solidified it crystallised well from aqueous methyl
alcohol in colourless prisms, melting at 128 — 129°. Fractional
crystallisation from the solvent just named, and also from a mixture

2006 LUFF AND KIPPING: THE RESOLUTION OF

of ethyl acetate and ether, failed to give any sign of resolution;
the melting jjoint of the salt obtained from ethereal solutions seemed
to be 3° lower than that of prejiarations from aqueous solvents — an
indication of dimorphism, which was not further examined.

The salt is soluble in methyl alcohol and hot ethyl acetate, but
only sparingly soluble in cold ether and in cold water.

Isomeric dX-IIydrindamides of Pheni/l-]i-toli/lphosphoric Acid.

These compounds were prepared by the interaction in ethereal
solution of phenyl-2?-tolyl2)hosphoryl chloride (1 mol.) and a slight
excess of the theoretical quantity (2 mols.) of fZZ-hydrindamine :
P0(0Ph)(0-CcH4Me)Cl + 2C9H9-NH2 =

PO(OPh)(0-CoH4Me)(NH-C9H9) + C9H9-NH2,HC1.

An immediate precipitate of <?^hydrindamine hydrochloride was
formed, and the reaction seemed to be at an end almost immediately,
but to ensure its completion the solution was left for twelve hours
at the ordinary temperature. The hydrochloride of the base was
then separated by filtration, and the ethereal solution was
evaj^orated at the ordinary temperature; the residue, a crj^stalline
solid mixed with oil, was washed with very dilute acetic acid, and
then fractionally crystallised from aqueous methyl alcohol.

a-Isomeride. — After a great many operations the substance mopt
sparingly soluble in methyl alcohol was obtained in fairly well-
defined, transparent prisms; it was dried over sulphuric acid until
constant, and analysed, with the following result :

01675 gave 0-4291 COo and 0-0902 HoO. C- 69-86; H = 5-9.
CooHgoOgNP requires 0 = 6965; H = 5-8 per cent.

This tZ^hydrindamide melts at 98 — 100°, and solidifies, on cooling,
to a crystalline mass, which does not melt until 104 — 105°, although
it sinters at lower temperatures. These observations seem to show
that this a-isomeride is dimorphous, and on at least two occasions
during its purification it separated from aqueous methyl alcohol
in crystals which melted at 105°, but the exact conditions required
for the production of this modification were not determined.

The compound is very readily soluble in methyl alcohol, chloro-
form, or ethyl acetate, and slightly soluble in boiling ether, but
only very sparingly soluble in boiling light petroleum, and prac-
tically insoluble in cold water.

^■Isomeride. — After having separated all the more sparingly
soluble portions (which consisted mainly of the o-isomeride), there
remained eight or ten fractions, which had been obtained by
systematically crystallising the mixture of hydrindamides from
methyl alcohol ; the most sparingly soluble portion melted at about

ASYMMETRICAL DERIVATIVES OF PHOSPHORIC ACID. 2007

94°, the most readily soluble one at 74°, the intermediate ones at
temperatures between these extremes in regular gradation. The
several portions were next systematically extracted with cold ether,
and all the more soluble material was then collected and fractionally
crystallised from a mixture of ether and light petroleum ; in this
way there was obtained, as the most sparingly soluble portion, a
preparation, obviously not quite pure, which sintered at about 72°,
melting completely at 74 — 76°. This sample was dried and
analysed :

0-1758 gave 0-4485 COo and 0-0951 IIoO. C = 69-57; H = 6-0.

CooHooO;jNP reqtiires 0 = 6965 ;"h = 5-8 per cent. _

As this result seemed to prove the existence of a hydrindamide
isomeric with the compound described above, the impure pre-
paration melting at 74 — 76° was fractionally crystallised from
aqueous methyl alcohol, and at last a small proportion of it was
obtained in long, colourless needles, melting at 85 — 87°. On
analysis :

0-1741 gave 0-4466 COo and 0-0930 HoO. 0 = 6996; H = 5-9.

That the substance melting at 85 — 87° is not merely an impure
form of the o-isomeride was proved by mixing it with an approxi-
mately equal proportion of the latter; the mixture sintered at 75°,
and was completely melted at 83°.

These two hydrindamines are so very similar in appearance and
in properties that their separation is only accomplished with very
great difficulty, a fact which is perhaps strong confirmatory evidence
of their isomerism. That the two substances are amides, and not
salts, is proved, not only by the analytical results, but also by the
fact that they are not apiorcciably changed by sodium carbonate in
aqueous alcoholic solution; in fact, they can be warmed in contact
with aqueous sodium hydroxide for some time without any base
being liberated.

Isomeric d'Hydrindamidcs of Fhenyl-'p-foli/lpkosp7io7'ic Acid.

The acid chloride was next treated with rZ-hydrindamine, as
described in the case of the c//-basc. The product, after preliminary
purification, was fractionally crystallised from aqueous methyl
alcohol, and after several operations the most sparingly soluble
deposit underwent no further change in properties.

a-Iso7?ier/de. — The more sparingly soluble compound, distinguished
as the a-isomeride, melted at 127°, and was analysed :

0-1652 gave 0-4216 COo and 0-0888 HoO. C = 69-6 ; H = 59.
C20H00O3NP requires C = 69-65; H = 5-8 per cent.

2008 LUFF Ax\D KH'PING : THE RESOLUTION OF

03744, made up to 20 c.c, gave, in a 2-dcm. tube, o-0-65°,
whence [o]p-17-4°.

$-Isnweride. — The more readily soluble fractions, which separated
from aqueous methyl alcohol in an oily condition, wei-e dried and
systematically crystallised from light petroleum (b. p. 65 — 75°);
tiic most readily soluble portion was then again treated with aqueous
methyl alcohol, and, after two crystallisations, the most sparingly
soluble deposit was collected. This sample melted at 82 — 86°, and
on analysis gave the following result:

0-1510 gave 0-3838 COo and 0-0818 H,0. C = 693 ; H - 6-0.

0-423, made up to 20 c.c, gave, in a 2-dcm. tube, o-0-90°, whence
Md-21-2°.

Although the specimen of the /3-isomeride was certainly not a
perfectly pure compound, these results prove beyond doubt that two
isomeric amides are formed by the interaction of c?-hydrindamine
and phenyl-^j-tolylphosphoryl chloride. The whole behaviour of the
original product is that of a mixture of equal quantities of nearly
related isomerides, and the isolation of the more readily soluble
one was, of course, hardly to be expected ; it was proved, however,
that the )3-isomeride was qiiite free from any hydrindamine salt,
and in these circumstances the fact that it has a higher specific
rotation than the a-isomeride is important proof of its real existence.
Except for the difference in melting point and the slight difference
in solubility, the two isomerides are very similar to one another
and to the isomerides obtained with c??-hydrindamine ; they both
crystallise in prisms, and dissolve freely in alcohol and most other
organic solvents, but are only sparingly soluble in cold light
petroleum and practically insoluble in water. Their chemical
behaviour is, of course, the same as that of the inactive isomerides,
and both may be boiled with sodium carbonate in aqueous-alcoholic
solution for some moments without any evolution of base taking
place.

Attempts to reconvert the amides into the acids were not
successful.

Isomeric l-Menthylamides of Phenr/l-'p-tolylphospJtoric Acid.

These compounds were prepared and purified in a manner similar
to that employed in the case of the hydrindamides. The crude,
oily product which slowly solidified was fractionally crystallised
from aqueous methyl alcohol, and after about three crystallisations
the most sparingly soluble fraction began to crystallise in well-
defined, prismatic needles.

ASYMMETRICAL DERIVATIVES OF PHOSPHORIC ACID. 2000

a-Isomeride. — After about three more crystallisations, the most
sparingly soluble fraction was a pure compound. On analysis :

01596 gave 0-4014 CO., and 0-1156 HoO. C = 68-6; H = 8-06.
C03H32O3NP requires C = 68-8; H = 7-98 per cent.

0-26, made up to 20 c.c, gave, in a 2-dcm. tube, a -0-84°, whence
[a]^-32-3°.

This Z-menthylamide melts at 109 — 110°; it is soluble in alcohol,
ethyl acetate, or chloroform, but is less readily soluble in ether or
light petroleum.

^-Isomeride. — After removing the most sparingly soluble portions
of the Z-menthylamide, the remaining fractions all melted at tem-
peratures ranging from 70 — 80° ; as further fractional crystallisation
from aqueous methyl alcohol proved to be useless, all these fractions
were collected, dried, and dissolved in light petroleum. From this
solvent, crystals could only be obtained with difficulty, owing to the
great solubility of the substance, so after separating some more
sparingly soluble material aqueous ethyl alcohol was employed ;
after protracted purification a sample, melting at 85 — 86°, was then
obtained. This specimen gave the following result on analysis :

0-1548 gave 0-3916 COo and 0-1134 HoO. 0 = 690; H = 8-14.
C.33H.5.P3NP requires C = 68-8 ;"'h = 7-98 per cent.

0-2214, made up to 20 c.c, gave, in a 2-dcm. tube, a — 0-84°,
whence [a\^-2,l-^°.

As in the case of the hydrindamides, this ^-isomeride cannot be
regarded as a perfectly jDure substance. Nevertheless, the observa-
tions made during the examination of the menthylamides can only
be explained on the assumption that the original product is a
mixture of isomerides, apparently in equal quantities. The absence
of any /-menthylamine salt from the )3-isomeride was, of course,
proved before analysis.

The isomeric /-menthylamides are very similar in properties, and
are readily soluble in all common organic solvents, but are prac-
tically insoluble in water.

University College,
nottinguam.

2010 DOBSON, FERNS; AXD PERKIN :

CCXX. — St/nthcsis of aycloIIcxanone-S-carhoxylic Acid.

Bv Mary Elizabeth Dobson, John Ferns, and
William Henry Perkin, jun.

The syutlaesis of carvestrene (Perkin and Tattersall, Trans., 1907,
91, 480) had for its starting point 7/^-hydroxybenzoic acid, which
was reduced by sodium and alcohol to c?/<:'/ohexanol-3-carboxylic
acid, and the latter then converted into r/zf/ohexancnc-S-carboxylic
acid by oxidation witli cluomic acid mixture :

The yield of this ketonic acid was very unsatisfactory, and the
preparation of the amount required for the synthesis of carvestrene
proved to be so laborious that it was found impossible to investigate
that important terpene and its derivatives in so thorough a manner
as we had hoped to have done. In order, if possible, to overcome
this difficulty, new experiments are being actively carried on,
and the present communication deals with a series of reactions
which have been undertaken with the object of synthesising eydo-
hexanone-3-carboxylic acid, and, although we have been successful
in this, the process is, unfortunately, still not suitable for the
preparation of large quantities of this acid. The various steps in
the synthesis are the following.

In the first jDlace, ethyl oxaladipate is prepared by condensing
ethyl oxalate with ethyl adipate in the presence of sodium
ethoxide (compare Wislicenus and Schwanhauser, Annaltn, 1897,
297, 110), and, on distilling this, it decomposes with elimination of
carbon monoxide and formation of ethyl butane-aSS-tricarboxylate :
COoEt-CO-CH(CO.Et)-CHo-CH„-CH.-CO.Et -^

' CH(CO.Et),-CH2-CH2-CH2-C02Et.

The sodium derivative of the latter ester reacts readily with
ethyl bromoacetate, with the formation of ethyl pentane-aBie-tetra'
carboxylate, C02Et-CHo-C(C02Et)2-CH2-CH2-GH2-C02Et, and, when
the product of the hydrolysis of this ester is heated, it yields
penta/ie-aSe-tricarhoxylic acid,

C02H-CH2-CH(C02H)-CH2-CH2-CH2-C02H.

The next step was to investigate the action of sodium on the
ester of this acid. When the formula of ethyl j)entane-d5e-tri-
carhoxylate,

da he

C02Et-CH2-CH(C02Et)-CH2-CH2-CH2-C02Et,
is examined, it is readily seen that condensation with elimination

SYNTHESIS OF cYcu)hp:xanone-3-carboxVL1c acid. 2011

of alcohol can take place cither between the CO^EL (d) and .tho
CH^ (h) to yield ethyl 5-carboxy<'yr/()pentanonc-2-acetatc (I), or

(I.) (II.)

between the CO.^Et (c) and the CHo (d), in which case ethyl cyclo-
hexanone-3 : G-dicarboxylatc (II) would be produced. On hydro-
lysis and elimination of carbon dioxide, the former would yield
fj/cZopentanone-2-acetic acid, and the latter ryc/ohexatione-
3-carboxylic acid :

CO,H.CH.,.CH<^^£?|^^ and CH,<^^^i^^>CH.CO,H.

Now, in condensations of this nature, where the two possibilities
exist, the usual experience is that the five-carbon ring is almost
invariably formed in preference to the six-carbon ring, and we
were therefore greatly surprised when we found that the product
of the action of sodium on ethyl pentaue-o5e-tricarboxylate is
evidently ethi/l cyc\ohexano77e-3 : Q-dicarhoxi/late. This is proved
by the fact that the ester actually obtained yielded, on hydrolysis
and elimination of carbon dioxide, an acid melting at 73 — 75°,
which was proved, by direct comparison with a specimen of the
acid prepared from y/t-hydroxybenzoic acid by Perkin and Tattersall
(loc. cit.), to be c//r/oliexanone-3-carboxylic acid. These experi-
ments therefore constitute a synthesis of this important acid, but
the process is very costly and the yield too small to make the
synthesis, in the meantime, of j^ractical importance.

This communication also contains an account of an attempt to
convert ethyl c2/c^opentanone-2-carboxylate into ethyl 1-methyl-
cyc^opentan-2-one-l-carboxylate, and then into ethyl 1-methyl-
c?/c/opentan-2-ol-l-carboxylate and ethyl l-methyl-A--cycZopentene-

-^CO-CH-CO.Et ^ -^CO-CiMe-CO.,Et '

-^CH(0H)-CMe-C02Et ^CH-CMe-COoEt-

1-carboxylate, in order that the latter ester might be ixsed in
the further synthesis of terpenes containing a five-carbon ring
(compare Haworth and Perkin, Trans., 1908, 93. 573).

Experimental,

Ethyl Pcntaiic-aZh^-tetracarhoxylate,
CO.,Et-CHo-C(COoEt)2-CHo-CH2-CH2-C02Et.

As explained on p. 2010, this ester is obtained when ethyl
bromoacetate reacts with the sodium derivative of ethyl butane-

2012 DOBSON, FERNS, AND PERKIN :

aSS-tricarboxylate, CH(C02Et)2-CH2-CH2-CH2-COoEt, an ester
wliioh we prepared in quantity by the method described by
Wislicenus and Schwanhauser (loc. cit.). Sodium (2"3 grams) was
dissolved in absolute alcohol (40 grams), mixed with ethyl butane-
a55-tricarboxylate (27'4 gi'ams) and ethyl bromoacetate (16'7
grams), and the whole heated in a reflux apparatus on the water-
bath for two hours. The product was mixed with water, extracted
with ether, the ethereal solution washed, dried, and evaporated,
and the residual oil several times fractionated under diminished
pressure, when a considerable quantity of a colourless oil distilled
at 210 — 212°/ 10 mm., and consisted of j)ure ethyl jjcntane-aSde-
tetracarhoxylate :
0-2112 gave 0-4371 COo and 0-1519 HgO. C = 56-4; H = 8-0.
C17H2SO8 requires C = 56-7j H = 7-8 per cent.

Ethyl Pentane-a8&-tricarhoxylate,
C0.2Et-CH2-CH(C02Et)-CH2-CH2'CH2-C02Et.

In order, in the first place, to obtain pentane-aSe-tricarboxylic
acid, ethyl pentane-a55e-tetracarboxylate was boiled with a mixture
of three times its volume of concentrated hydrochloric acid, diluted
with an equal volume of water, for seventeen hoixrs in a reflux
apparatus, the condenser of which was removed from time to time
to allow alcohol to escape. The hydrochloric acid was then distilled
off under diminished pressure, and the syrupy residue heated in an
oil-bath until the evolution of carbon dioxide ceased. The crude
pentane-a5e-tricarboxylic acid thus obtained was esterified by
digesting with alcohol and sulphuric acid for several hours, the
ester was then precipitated with water, extracted with ether, the
ethereal solution washed with sodium carbonate, dried, and frac-
tioned, when almost the whole quantity distilled at 195 — 197°/
15 mm., and consisted of pure ethyl 'pentane-aSe-tricarboxylate:

0-1502 gave 0-3212 COo and 01134 H.O. C = 58-3; H = 8-4.
Ci^HojOg requires C = 58-3; H = 8-3 per cent.

When this ester was digested with dilute hydrochloric acid, it
was readily hydrolysed, and, after distilling off the hydrochloric
acid under diminished pressure, a syrup remained which gradually
crystallised.

The mass was left in contact with porous jDorcelain until quite
dry, and then crystallised from a very little hydrochloric acid, in
which the acid is very readily soluble. The following analyses
were made with different preparations; the first was carried out
with a specimen of the acid which had remained for some days
simply exposed to the air, and the second with a specimen of the

RVNTHESIS OF CYOLOHEXANONE-S-CARBOXYLIC ACtD. 201^

acid which had been dried for twenty-four hours over sulphuric
acid :

0-1135 gave 0-1890 CO2 and 00640 HoO. C = 45-4; H = 6-3.
0-1260 „ 0-2100 CO2 „ 0-0710 HoO. C = 45-4; H = 6'3.
CgHioOcpIoO requires C-45-lf H = 6-l per cent.

It appears, therefore, from these analyses, that 'pentane-aSe-tri-
cnrhoxylic acid crystallises from hydrochloric acid with ^HgO.

It crystallises in crusts, melts at about 96°, and, on cooling, sets
to a resin which remains in that condition for months.

Ethyl pentane-aSe-tricarboxyate has been obtained by Kbtz and
Schiller {Aiinalenf 1906, 350, ,241) by treating the sodium
derivative of ethyl c?/(7opentauone-2-carboxylate with ethyl bromo-
acetate and then hydrolysing the ethyl <'//(7opentanone-2-carboxylate-
2-acetate thus jiroduccd with sodium ethoxide, when fission of the
ring takes place according to the scheme :

-^CO-C(CO.,Et)-CH2-C02Et ^

2^C0.Et CH(COoEt)-CH2*C02l2t.

These investigators give the boiling point of ethyl pcntane-
aSe-tricarboxylate as 188 — 189°/ 18 mm., which is rather lower
than the boiling jDoint (195 — 197°/ 15 mm.) recorded by us. They
also hydrolysed the ester with hydrochloric acid, but were unable
to obtain the acid in a crystalline condition ; they, however, describe
a crystalline anhydride, CgHjoO-,, which melted at 95°.

Tjtlujl cycloH exanone-^ : Q-dicarhocnjIatei
C02EfCH<^'J|^^^^2>CH-C02Et.

This ester is produced when sodium reacts with ethyl pentand-
a5e-tricarboxylate under the following conditions.

In a flask fitted with a ground-in condenser tube, sodium (4-7
grams) is melted under boiling toluene, vigorously shaken, and,
when cold, the toluene is decanted from the " molecular sodium,"
the latter washed with benzene, mixed with 150 c.c. of dry benzene,
and then ethyl pentane aSe-tricarboxylate (30 grams) added, and
the whole heated on the water-bath for three hours. The brown
product is mixed with ether (400 c.c.) and excess of dilute hydro-
chloric acid, the ether-benzene solution well washed, dried, and
the ether and benzene distilled off. The brown oil which remained
was twice fractionated, when a good yield of a colourless oil was

VOL. XCV. 6 U

2014 DOBSON, FERNS, AND PERKIN :

obtained which distilled at 175 — 180°/20 mm., but apparently with
slight decomposition, since the analytical results agreed only
approximately with the thcoi"etical :

01655 gave 0-3524 CO.. and 0-1201 HoO. C = 58-l ; H = 8-l.
0-1096 „ 0-2335 COo „ 0-0782 HoO. C = 58-l ; H = 7-9.
CjoHigOj requires C = 59-5; H = 7-5 per cent.

Ethyl cyclohexanone-S : 6-dicafboxi/Iafe has an odour somewhat
resembling that of ethyl acetoacetate, and gives in alcoholic solu-
tion a purple coloration on the addition of ferric chloride.

Synthesis of cy c\oHexanone-Z-carhoxylic Acid,

As explained on p. 2011, this acid is produced when ethyl cyclo-
hexanone-3 : 6-dicarboxylate is hydrolysed with hydrochloric acid.

The crude ester is boiled in a reflux apparatus with a considerable
quantity of 2 per cent, hydrochloric acid for about three days, and
until a small quantity, after extraction with ether, gives no colora-
tion with ferric chloride. The clear solution is saturated with
ammonium sulphate, extracted many times with ether, the ethereal
solution dried, evaporated, and the crude dark brown ketonic acid
(20 grams) converted into the ester by leaving it in contact with
alcoholic hydrogen chloride (75 c.c. of a 2 per cent, solution) at
the ordinary temperature. After three or four days, the bulk of
the alcohol is removed by distillation under diminished pressure,
the residue mixed with water, extracted with ether, the ethereal
solution well washed, dried, and evaporated, and the ester purified
by distillation, when almost the whole quantity passes over at
13.5 — 137°/20 mm. (compare Perkin and Tattersall, Trans., 1907,
91, 491):

0-1086 gave 0-2565 CO2 and 0-0842 HoO. C = 64-l; H = 8-6.
0-1019 „ 0-2372 CO2 „ 0-0795 HoO. C = 63-0 ; H = 8-5.
C9HJ4O3 requires C = 63-5; H = 8-2 per cent.

This ethyl cycZohexanone-3-carboxylate was digested with 50 c.c.
of a 2-5 per cent, solution of hydrochloric acid until a clear solution
resulted, ammonium sulphate was then added, and the whole very
thoroughly extracted with ether. The ethereal extract, after
drying and evaporating, yielded a viscid syrup, which distilled
at 195 — 197^/20 mm., and the distillate gradually crystallised.

In contact with porous porcelain, traces of oily impurity were
rapidly removed, and the residue separated from benzene in small,
glistening prisms, which melted at 73 — 75°, whereas the melting

SYNTHESIS OF CYCLOHEXANONE-3-CAKBOXYLIC ACID. 2015

point of r//67c»hcxanoue-3-carboxylic acid is stated by Pcikin and
Tattcrsall {loc. cif., p. 492) to be 75—76°:

0-1392 gave 0-3001 COo and 0-0864 ILO. 0 = 588; 11-6-9.
C7HJ0O3 requires C = 59-l; H = 70 per cent.

The semicarhazone. — When an aqueous solution of the acid was
mixed with semicarbazide hydrochloride and sodium acetate there
was no immediate precipitation of the semicarhazone, but, on long
standing, this derivative separated as a sandy jiowder, which, after
crystallisation from methyl alcohol, melted and decomposed at
183—184°:

0-0699 gave 12-7 c.c. No at 14° and 767 mm. N = 21-6.
CgHjgOgNa requires N = 2r2 per cent.

The properties of the ketonic acid are therefore exactly those
of cyc/ohexanone-3-carboxylic acid described by Perkin and
Tattersall (loc. cit.), and the identity of the specimens, prepared in
such different ways, was confirmed by the fact that, when intimately
mixed, there -was no alteration in melting point.

Ethijl cycloPentanone-2-carboxylate,

PR ^^^2*9^2

2^CO-CH-C02Ef

This ester was first prepared by Dicckmann (Ber., 1894, 27,
103) by the action of sodium on ethyl adipate and a little alcohol
at 120°, but, as the result of several experiments, Ave have found
that the reaction is best carried out under the following conditions.

Sodium (11-5 grams) is melted under boiling toluene and
vigorously shaken, the whole is then allowed to cool, the toluene
decanted from the '' molecular " sodium, and then a solution of
ethyl adipate (50 grams) in dry benzene (100 c.c.) is added, and
the whole heated on the water-bath in a reflux apparatus for two
hours. The product is mixed with ether, decomposed with ice
and dilute hydrochloric acid, the ether-benzene solution washed,
dried, and evaporated, and the residual oil fractionated under
diminished pressure, when almost the whole quantity distils con-
stantly at 132°/ 30 mm. The distillate, which was obtained in a
yield of 27 grams, gave a blue coloration when ferric chloride was
added to its alcoholic solution :

0-1302 gave 0-2924 CO.. and 0-0913 HoO. C = 61-3; H = 7-8.
CgHjoOs requires C = 6r5; H = 7-7 per cent.

Wislicenus and Schwanhauser (Annalen, 1897, 297, 112) state
that ethyl cyc?opentanone-2-carboxylate distils at 120°/22 mm.
When this ester (25 grams) was added to a solution of magnesium
methyl iodide (containing 7-7 grams of magnesium) a vigorous

6 R 2

2016 SYNTHESIS OF CVCLOHEXANONE-S-CAftBOXYLIC ACID.

action took place, and the yellow magnesium derivative, which first
separated, soon became colourless. The product, isolated in the
usual manner, and hydrolysed with alcoholic potassium hydroxide,
j-ielded adipic acid, and there was no evidence that any hydroxy-
niethyl acid had been produced. It is obvious, therefore, that ethyl
r//f/opentanonc-2-carboxylate reacts with magnesium methyl iodide
as an enolic modification.

Ethyl \-Mct]iylcyc\oi}t7itan-2-one-\-carhoxyIate,

-^C0-CMe-C02Ef

This ester has already been described by Boiiveault {Bull. Snr.
chim., 1899, [iii], 21, 1019), who. obtained it from the sodium
derivative of ethyl r^(7ojDentanone-2-carboxylate by the action of
methyl iodide, and he states that it distils at 108°/ 22 mm. We
have prepared it in considerable quantities by the same process, and
observed the somewhat higher boiling point, 120 — 122°/ 30 mm. :

0-126 gr.ve 0-2932 CO. and 0-0918 HoO. C = 63-5; H = 8-l.
C9HJ4O3 requires C = 63-5; H = 8-2 per cent.

Ethyl l-methylryf/opentan-2-one-l-carboxylate is a colourless oil
with a j^leasant odour ; it gives no coloration with ferric chloride.

Reduction with Sodium Amcdgam. — The results obtained in our
experiments on the reduction of the above ketonic ester with sodium
amalgam varied very much; in some cases the reduction appeared
to proceed normally, with the formation of l-niethyk'//f?opentan-2-ol-
1-carboxylic acid, whilst, in other cases, the ketonic ester suffered
hydrolysis with formation of methyladipic acid. On one occa-
sion, an experiment, carried out under the following conditions,
appeared to proceed normally. The pure ketonic ester (20 grams),
dissolved in dilute alcohol, was treated in the cold with 1 kilo, of
freshly prepared sodium amalgam (3 per cent.), hydrochloric acid
being added from time to time in such a way that the solution
was always nearly neutral. The product was acidified, saturated
with ammonium sulphate, extracted twelve times on the machine,
the extracts were combined, dried, evaporated, and the residue
esterified by warming on the water-bath with alcoholic sulphuric
acid (10 per cent.) for six hours. The ester, isolated in the usual
manner, distilled at 158 — 160°/ 100 mm., and gave the following
results, which agree fairly well with those required for ethyl
lmethylcycZopentan-2-ol-l-carboxylate:

0-1721 gave 0-3926 COo and 01411 H.O. C = 62-3; H-91.

CgHjgOg requires 0 = 628; H = 9-3 per cent.
When this ester was boiled for three hours with three times

THE ACYL-BOllNYLAMINES. TAUT I. 2017

its volume of acetic anhydride, an oil was obtained which distilled
at 147 — 151°/40 mm., and yielded numbers agreeing closely with
those reqixired for ethyl 2-acetoxy-l-methylcy67opentane-l-carboxyl-
»te:

0-1731 gave 0-3907 CO. and 0-1318 HgO. C = 61-5; H = 8-5.
CjiHigO^ requires 0 = 61-7; 11 = 8-4 per cent.

Some of the ethyl l-methylcyc/opentan-2-ol-l-carboxylate was
heated with two molecular proportions of j^hosphorus pentachloride
for one and a-half hours on the sand-bath, and the product poured
into alcohol. The ester thus obtained distilled at 160 — 170°/40 mm.,
and, on analysis :

0-1696 gave 0-1504 AgOl. 01 = 21-9,
whereas ethyl 2-chloro-l-methylc//fZopentane-l-carboxylate contains
18-3 per cent, of chlorine. This chloro-estcr proved to be remark-
ably stable, since it was scarcely attacked by boiling with diethyl-
aniline, and, as all our other attempts to eliminate hydrogen
chloride and to obtain the corresponding unsaturated ester were
unavailing, the subject was not further investigated.

The University,

Manchester.

CCXXI. — The Acyl-horuylamines. Part I. Fatty
Bornylamides.

By Percy Faraday Frankland and Fred Barrow.

In order to determine the effect of substitution on the rotatory
power of optically active compounds, attention has already been
directed by one of us to an examination of active amides and their
substitution products (Frankland, Wharton, and Aston, Trans.,
1901, 79, 266; Frankland and Slator, ibid., 1903, 83, 1349; Frank-
land and Ormerod, ibid., 1903, 83, 1342; Frankland and Done,
ibid., 1906, 89, 1859; and Frankland and Twiss, ibid., 1906, 89,
1852). All these investigations have had as their starting point
the amide of an active acid (glyceric, malic, or tartaric), and the
effect of substitution of the hydrogen of the amido-group by various
radicles on the rotatory power has been examined.

Amides derived from optically active amines have, however,
received comparatively little attention. Numerous acyl derivatives
— chiefly acetyl and benzoyl — have, indeed, been described, but very
little systematic work has been* done on the substitution of the

2018 FRANKLAND AND BARROW:

hydrogen of the amino-group of active amines by negative groups.
The onlv amines -which have been studied from this point of view
are d- and 7-mcuthylamines and Z-fenchylamine. Of these, the
formyl, acetyl, propionyl, and but3rryl derivatives were prepared
bv Binz, and their rotations in solution examined (Zeitsch. fhysikal.
Chem., 1893, 12, 723).

With the object of studying the effect of substitution on the
rotatory power of an active amine, we have examined the optical
properties of some derivatives of bornylamine, formed by replacing
the amino-hydrogen by various aliphatic and aromatic acyl groups.

Bornylamine was first obtained by Leuckhart and Bach (Ber.,
1887, 20, 104) by heating camphor with ammonium formate, and
subsequent hydrolysis of the resulting formobornylamide. The
formyl, acetyl, and benzoyl derivatives were described, but no
account of their optical behaviour was given.

Forster (Trans., 1898, 73, 386) obtained bornylamine by the
reduction of camphoroxime with sodium in amyl-alcoholic solution.
He showed that the base, obtained either by heating camphor with
ammonium formate, or by reduction of the oxime, was not a single
chemical individual, but consisted of a mixtvire of two stereoisomeric
amines having rotations of opposite sign, which can be readily
separated by taking advantage of the difference in the solubility of
their hydrochlorides.

Dextrorotatory bornylamine, the hydrochloride of which is the
less soluble, is the more easily obtained, and Forster (Trans., 1899,
75, 934, 1149) prepared a large number of its derivatives, more
particularly investigating the alkyl-bornylamines as well as the
condensation products which it forms with aromatic aldehydes.
The acyl-bornylamines examined by him are given below, together
with their rotations in ethyl-alcoholic solution.

Eolation in Ethyl-Alcoholic Solution (Forster).

c. t. [aX, [M];;.

FonTioboiiiylaniide 3-.o672 20" -42-1° -76-2°

Acetobornylamide 2-9260 20 42-9 83-6

Benzobornylamide 4-00.52 20 21-8 .55-9

Bcnzomelhylbornjdaiiiide. 1-7716 24 6.5-5 177-.5

Heiizoethyrhornylamide ... 2-7612 21 65-2 18.5-7

Benzoproi'ylbornylamide 1-9608 14 60-4 180-5

The present communication deals with the preparation and
properties of the formo-, aceto-, propiono-, and ??-butyro-bornyl-
amides.

The formo- and accto-compounds, which have previously been
described by Forster, were prepared by heating bornylamine with
the corresponding acid, whilst the propiono- and butyro-derivative?

THE ACYL-BORNYLAMINES. PART I. 2010

■were obtained by the interaction of bornylamine and the acid
chloride in ethereal solution.

The rotatory powers were, in all cases, determined in methyl and
ethyl alcohol, as well as in pyridine and glacial acetic acid solution.
The observations were all made at 20°, and on solutions of approxi-
mately 5 and 10 per cent, strength.

The results of the polarimetric determinations are summarised
in the followius: table :

?'

Forino- Aceto- Propiono- n-liutyro-

boinylamide. bornylamide. bornylamide. bornylaiiiide.

(approx.) [«]f. [U]f. [a]f. [M]f. [a]f. [M]'f. [a]f. [U]f.

Ethyl- A. IcoJiolic Solution.
5 -43-17° -78-14° -43-48° -84-79° -40-79° -85-25° -37-73° -84-14°

Methyl- A Icoholic Solution.

5
10

-40-88°
41-01

-73-99°
74-23

-41-93° -81-76° -38-68° -80-84°
4210 82-10 39-48 82-51

-35-73°
35-86

-79-65'
79-97

Glacial Acetic Acid Solution.

5
10

-13 80°
15-30

-24-99°
27-69

-34-80° -67-85° -37-19° -77-72°
36-14 70-47 37-54 78-46

Pyridine Solution.

-34-89°
35-29

-77-80'
78-70

5
10

-16-96°
18-60

-30-70°
33-67

-11-97° --23-32° -14-64° -30-60°
15-14 29-52 16-38 34-23

-12-57°
15 06

- 28-03'
33-58

The relationship existing between the molecular rotations of the
various members of the series is more readily seen from the accom-
panying diagram. It will be observed that the rotatory powers of
the aliphatic acyl-bornylamides, which we have investigated, depend
to a very great extent on the natui-e of the solvent in which they
are examined. These substances show the greatest rotatory power
in ethyl-alcoholic solution, and, with the excejDtion of the formo-
derivative, the smallest in pyridine. The alteration, however, in the
rotatory power of these acyl-bornylamines, caused by the change in
the nature of the solvent, varies considerably with each member of
the series. In methyl alcohol, ethyl alcohol, and glacial acetic acid
solution, the activity of the formo-derivative shows by far the
greatest variation, the value of the molecular rotation falling from
— 78-14° in ethyl-alcoholic solution to —24-99° in glacial acetic acid
- — a difference of 5315°; in the case of the butyro-compound, on
the other hand, the alteration in the rotatory power in the same
solvents is smaller than that observed with the other members of
the series, the molecular rotation falling from -84-14° in ethyl

2020

FllANKLAND AND BAKEOW :

alcohol to -77'SO'^ in glacial acetic acid solution — a difference of
only 6-34°.

Tims tlie variation in tlie rotatory power brought about by change
in the nature of the solvent becomes less and less marked as the
series is ascended. This gradual diminution in the effect of the
solvent is very clearly shown in the diagram by the convergence of
the curves marked ethyl alcohol, methyl alcohol, and acetic acid, as
we pass from the lowest to the higher members of the series.

It may also be pointed out that all these aliphatic acyl-bornyl-
amines have a greater rotation in ethyl alcohol than in methyl

Molecular rotation of the aliphatic hornylaminex in pyridine, ethyl and methyl alcohol,
and acetic acid solution.

[M]i?- -G0°

Formyl.

Acetyl.

Fropionyl.

80°

10°

-20°

Buiyryl.

alcohol, and again a greater rotation in methyl alcohol than in
glacial acetic acid solution, whilst the rotation in pyridine is,
excepting in the case of formobornylamide, less than in any of the
other solvents. The rotatory power of these substances in the
different solvents is also influenced by the concentration, but the
variation thus produced is very small, excepting in the case of
pyridine. In all cases, however, increase in concentration is
attended by increased rotatory power.

It is particularly noteworthy that in this series of the aliphatic
acyl-bornylamines the maximum molecular rotation does not

THE ACYL-BORNYLAMINES. PART I. 2021

uniformly fall on the same term of the series, but its position varies
according,' to the solvent cmployecl. Thus in both methyl- and
ethjl-alcoliolic solutions the maximum occurs on the second term ;
in glacial acetic acid solution, on the other hand, the rapid increase
in the rotatory power sliown between formo- and aceto-bornylamide
is maintained up to the propiono-derivative, which does not
materially differ in rotatory power from the butyro-compound, and
thus represents the maximum.

Turning now to the rotatory powers in pyridine solution, it will
be observed that these show much less regularity than those in the
other solvents. Instead of rising continuously to a maximum and
then gradually diminishing or remaining constant, as in the case of
the alcoholic and glacial acetic acid solutions, the molecular
rotations in pyridine solution show an alternation pf high and low
values. This irregular behaviour of .the aliphatic acyl-bornylamines
in pyridine is undoubtedly to be referred to an irregularity in the
influence of the solvent on the first member of the series. It has
already been pointed out that the aceto-, propiono-, and w-butyro-
bornylamides have a greater rotatory power in methyl-alcoholic
than in glacial acetic acid solution, and, again, a greater rotatory
power in acetic acid than in pyridine. Moreover, the same
regularity has been observed in the rotatory powers of the seven
aromatic acyl-bornylamines described in the following communi-
cation. With the formyl derivative, however, this is no longer the
case, the molecular rotation in pyridine solution being greater than
that in glacial acetic acid solution. Owing to some disturbing
influence of the solvent, the rotatory power of the first member in
pyridine solution is thus much higher than was to be anticipated
from a consideration of the behaviour of the other members. It
may, however, be pointed out that if the first term of the series
be neglected, then the molecular rotatory powers of the succeeding
aliphatic acyl-bornylamines in pyridine solution show the same
beliaviou.r as in the other solvents, in that they attain a limiting
value at the acetyl or propionyl term.

As regards the influence of substitution on the rotatory power
of bornylamine, it is observed that the acyl group exerts a marked
lasvorotatory effect. The dependence of the rotatory power on the
qualitative nature of the substituting group is shown in the follow-
ing table, in which the rotatory powers of the corresponding alkyl-
and acyl-bornylamines in ethyl-alcoholic solution are contrasted :

2022

FKANKLAND AND BARROW :

notations in EtJiyl-Alcoholic Solution.
Bornylamim : p = 5-006, [M]i;° + 72-51°.

Acyl-

boniylamiiics. p.

Formo- 4-9984

Aceto- 4-9380

Propiouo- ... 5-0013

?i-ButATO- ... 5 0021

Bcnzo-* 4-9940

o-Nitrobenzv*
7«-Nitrobenzo-
/)-Nitrobenzo-''
o-Toluo-* ...
»«-Toluo-* ...

4-9799
2-6399
4-2770
5-0002
5-0073

t°.

tM]„.

20°

-78-14°

20

84-79

20

85-25

20

84-14

20

58-93

20

67-62

20

84-29

20

50-58

20

51-60

20

60 70

20

39-43

j3-Toluo-* 5-0187

* See foUowinff communication.

Alkyl-

bornylamines.t c. f. [M]d.

Methyl 2 0256 23° +135-3"

Ethyl 2-6728 15 136-4

m-Propyl 2-0840 16 140-4

isoPropyl 20140 16 123-4

?(-Butyl 1-9932 16 1354

Benzyl 2-2284 20 184-0

o-Nitrobex)zyl 2-0272 22 176-2

2J-Xitrobenzyl 2-0148 22 191-8

+ Forster, Traus., 1899, 75, 934.

Introduction of a positive radicle increases the dextrorotation of
bornylamine, -whereas the corresponding acyl group exerts such a
marked laevorotatory effect that its introduction is in all cases
attended by a comjolete change in the sign of the rotation.

Experimental.

The bornylamine used in these experiments -was prepared by
reducing camphoroxime with sodium in amyl-alcoholic solution ; the
hydrochlorides of the mixed amines so jjroduced were recrystallised
from water until of constant rotatory power.

The following polarimetric values were obtained for the hydro-
chloride and free amine in two different preparations :

Rotatory Poicer of Bornylamine Hydrochloride.

p. d 2074°. I in mm. af. [a]'f' .

Prep. I

„ n

Prep. I
., II

Ethyl- Alcoholic Solution.

4-868
5-213

0-8032
0-8034

299-3
299-3

+ 2-66°
2-84

+ 22-73°
22-66

Rotatory Power of Bornylamine.
Ethyl- A Icoholic Solution.

5-0557
5-0060

0-7949
0-7972

299-3
299-3

+ 5-68°
5-66

+ 47-22°
47-39

[M]^

+ 42-85°
42-73

+ 72-22°
72-51

The value given above for the rotatory power of tlie amine is
rather higher than that found by Forster, namely, [ajff + 45-5°,
c = 4-0496.

THE ACYL-BORNYLAMINES. PART I. 2023

Formohornylamide.

This compound w.as prepared in the manner given by Forster, by
heating bornylamine with several times its weight of anhydrous
formic acid for some hours, and purified by crystallising from dilute
alcohol ixntil it possessed a constant rotatory power.

It forms lustrous, flat plates, which possess no definite melting
point, but begin to soften at 83°, and arc not completely melted
until 91°. It is readily soluble in alcohol, pyridine, glacial acetic
acid, or benzene :

0-1592 gave 10-7 c.c. No (moist) at 13-5° and 750 mm. N = 7-80.
CjiHjgON requires N = 7"73 per cent.

Hotatorrj Power of Formohornylamide.
p. d 2074°. I in mm. df. [o]^\ [M]'f .

Ethyl- Alcoholic Solution.

5-3155

0-8003

199-84 -3-67°

-43-17°

-78-14°

4-9984

0-8001

•

199-84 3-45
Methyl-A Icoholic Solution.

43-17

78-14

4-9747

0-8046

389-9 -6-38°

-40-88°

-73-99°

9-9845

0-8127

199-84 6-65

41-01

74-23

Glacial Acetic Acid Sohition.

5-5607

1-0496

199-84 -1-61°

-13-80°

-24-99°

9-6903

1-0-199

199-84 311
Pyridine Solution.

15-30

27-69

5-0156

0-0800

389-9 -3-2.5°

-16-96°

-30-70°

10-0200

0-9829

199-84 3-66

18-60

33-67

The value found by us for the rotation in ethyl-alcoholic solu-
tion is slightly greater than that found by Forster, namely,
[a]r-42-r, c = 3-5672.

The formobornylamide employed in the above polarimetric deter-
minations melted indefinitely at 83 — 91°; Forster gives the melting
point of this compound as 93°. It was therefore considered
advisable to repeat the pi-^eparation, but we have only been able to
confirm our earlier result. The details of the experiment are given
below. Eight grams of bornylamine were dissolved in 50 grams
of anhydrous formic acid, and the mixture heated to boiling
for nine hours. The formobornylamide (7-5 grams) was precipitated
by pouring into water and crystallised from dilute alcohol, melting
point 82- — 92°. On crystallising a second time from the same
solvent, the com^Dound melted at 81 — 91°, and gave the following
polarimetric values in methyl-alcoholic solution :
p = 10-066, c? 2074° = 0-8191, Z= 199-84 mm., ail' -6-72°, [aji;' - 4079°.

2024 FRANKLAND AND BARROW :

Tlic product was again rccrystalliscd from dilute alcohol. It again
melted at 81 — 91°, and gave the following polarimetric results in
methyl-alcoholic solution :
;, = 10-001, (£ 2074° = 0-8176,/= 199-84 mm., ai?- 6-66°, [a]^'- 40-76°.

The above rotatory powers are identical and agree very closely
with those already given for the first preparation. Further crystal-
lisation from alcohol or light petroleum produced no change in the
melting point. The bornylamine used in these preparations had a
specific rotation of +47"37° in ethyl-alcoholic solution — a value
rather higher than that given by Forster, The indefinite melting
point observed by us for the formo-derivative cannot, therefore, be
referred to admixture of formoneobornylamide, for the presence of
the neo-base in the original amine would have diminished the dextro-
rotation.

A cetohornylamide.

This was also prepared in the same manner as that described by
Forster, namely, by boiling bornylamine with several times its
weight of glacial acetic acid, to which a few drops of acetic
anhydride had been added. The mixture was poured into water,
and the acetobornylamide, separating out, recrystallised from a
mixture of benzene and light petroleum. It is thus obtained in
small, flat jilates, melting at 145"5°, readily soluble in alcohol,
ethyl acetate, benzene, or acetone, but only sparingly so in light
petroleum :

01997 gave 15-2 c.c. N. (moist) at 11° and 762-5 mm. N-7-26.
C12H21ON requires N = 7'18 per cent.

Ttotatory Power of Acctohoinylamide.
p. rf2074°. Hiimm. o^''. [ojf. [M]f.

E thyl-Alcoholic Solution.
4-938 0-7998 199-84 -3-43° -43-48° -8479°

Methyl- Alcoholic Solution.

5 005
10088

0-8055 199-84
0-8150 199-84

-3-38°
6-92

-41-93"
42-10

-81-76°
82-10

Glacial Acetic

Acid Sola

tion.

4-958

5-014

10-021

1-049 199-84
1-049 199-84
1-048 99-9

Pyridine

-3-63°
3-64
3-79

Solution.

-34-93°
34-65
36 14

-68-11°
67-58
70-47

4-904
10-015

0-9790 389-9
0-9800 199-84

-2-24°
2-97

-11-97"
15-14

-23-32°
29 02

TTTE ACYL-PORNYLAMINES. PART I, 2025

The value obtained by ixs for the rotation of acctobornylamide
in ethyl-alcoholic solution agrees very closely with that given by
Forster, namely, [aji;^- 42-9°, c = 2-1)260.

Propio n u h ornyla m ide.

Twelve grams of bornylamine were dissolved in 100 c.c. of ether,
and an ethereal solution of propionyl chloride slowly run in. A
dilute solution of sodium hydroxide in water was then added, and
the mixture well shaken in order to decompose the bornylamine
hydrochloride, which separated out. Addition of propionyl chloride
■was then continued until about one and a-half times the calculated
amount had been added. On evaporating the ethereal solution, a
colourless oil was left behind, and this quickly solidified to a white,
crystalline mass. The projDionobornylamide was purified by dis-
solving in acetone, adding water until a permanent turbidity was
almost produced, and then allowing the acetone partly to evaporate
at the ordinary temperature. It is thus obtained in small, flat,
colourless needles, which begin to soften at 110° and melt at 117°.
It is readily soluble in benzene, light petroleum, chloroform, acetone,
or alcohol, and separates from hot solvents in the form of an oil:

0-2104 gave 12-4 c.c. No (moist) at 13° and 745-6 mm. N = 6-82.
C13II23ON requires N = G"70 per cent.

liotatory Power of P rojiionohornylainide.
p. d20°li°. Hninm. df. [ojf. [M]f.

Ethyl-A Icoholic Solution.

r.-0047

0-7983 389-9 -6-30'

-40-44°

-84-52°

.'■.•0013

0-7982 389-9 6-35

40-79

85-25

(reeryst. )

Methyl- Alcoholic Solution

5-0055

0-8028 389-9 -6-06°

-38-68°

-80-84°

9-9974

0-8113 199-84 6-40

39-48

82-51

Glacial Acetic Acid Solution.

5-0249

1-047 389-9 -7-63°

-37-19°

-77-72°

10-0087

1-045 199-84 7-85

Pyridine Solution.

37-54

78-46

4-9970

0-9780 389-9 -2-79°

-14-64°

-30-60"

9-9805

0-9797 199-84 3-20

16-38

34-23

n-Butyroh ornylamide.

This was prepared by the interaction of ?7-butyryl chloride and
bornylamine in ethereal solution in a similar manner to that

•2026

FRANKLAND AND BARROW :

described for the propiouo-compound. On evaporation of the ether,
butyrobornylamide was obtained as a viscid, colourless oil, -which
quickly solidified on cooling. It -was finely powdered and shaken
with dilute sodium carbonate for about three hours in order
to remove butyric acid and chloride. On crystallisation from
acetone, butyrobornylamide was obtained in small plates, melting
at 97°. It is readily soluble in alcohol, chloroform, ethyl acetate,
or pyi'idine, and less so in benzene :

0-2587 gave 13-75 c.c. No (moist) at 12° and 766-9 mm. N = 6-36.
C14H05ON requires N = 6-28 per cent.

Rotator;/ Poiver of n-Biityrohornylamide.

d 2074°. I ill mm. a'f , [o]'f ',

Ethyl- A Icoholic Solution.

[M]f

4-7930
5-0021

0-7980
0-7980

199-84
199-84

-2-89°
3-01

-37-81°
37-73

-84-31'
84-14

Methyl- A Icoholic Solution

4-9780
10-009

0-8047
0-8131

199-84
199-84

-2-86°
5-83

-35-73°
35-86

-79-65=
79-97

Glacial Acetic

Acid Solution.

5-0337
10-016

1-048
1-044

199-84
199-84

Pyridine

-3-68°
7-38

Solution.

-34-89°
35-29

-77-80
78-70

4-921
10-005

0-9783
0-9796

389-9
199-84

-2-36°
2-95

-12-57°
15-06

-28-03°
33 -.^j8

University,

Birmingham.

CCXXI I . — Tlte A cyl-hornylamines.

Bornylamides.

Part II. Aromatic

By Percs Faraday Frankland and Fred Barrow.

In the foregoing communication the optical activity of some
derivatives of bornylamine formed by the substitution of the aminic
hydrogen atom by aliphatic acyl groups has been described. In
the present communication we have confined our attention to the
aromatic acyl derivatives, having prepared and examined the
rotations of the benzo-, the three toluo-, and the three nitrobenzo-
bornylamides, firstly as a contribution to the study of the relation-

THE ACYL-BORNYLAMINES. PART 11. 2027

ship between position-isomerism and optical activity, and secondly
with the object of coniparin<j; the rotatory elTcct of the methyl and
nitro-groups when substituted in the ortho-, meta-, and para^
positions of the benzene ring.

Of these derivatives, only benzobornylamide has been previously
prepared (Forster, Trans., 1898, 73, 393). The aromatic bornyl-
amides described in the present paper were all prepared by the
interaction of ethereal solutions of the acid chloride and bornyl-
amine in the presence of an aqueous solution of potassium
hydroxide.

The rotatory powers were determined in the same solvents as
those employed in the case of the aliphatic bornylamides, namely,
ethyl alcohol, methyl alcohol, pyridine, and glacial acetic acid.
The rotatory power of the isomeric nitrobenzobornylamides in the
last three solvents was investigated at various temperatures, ranging
from 20° to about 45°, but in the case of the benzo- and toluo-
bornylamides the rotations at only one temperature, namely, 20°,
were observed. Determinations of the molecular solution vokimes
of the nitrobenzobornylamides in the same solvents have also been
made.

The more important values obtained for these compounds are
given below :

o-N iProh enzoh 07-nylamide .

Solvent. p. [a]'f . [MJf . Mol. sol. vol.

Ethyl alcohol 4-9799 -22-39° -67-62° —

Methyl alcohol 5-0654 30-^2 91-57 246-1 c.c.

Glacial acetic acid 3-9454 13-54 40-89 250-9 ,,

Pyridine 5-0011 5-8S 17-76 250-4 ,,

, 10-0»70 7-67 23-16 2550 ,,

vci-Nitrohenzohornylamide.

Solvent. p. [ajf.

Ethyl alcoliol 2-6399 -27-91°

Methyl alcohol 1-9190 -24-62

Glacial acetic acid 3-8987 -12-16

Pyridine 5-0079 +27-22

9-9862 +22-16

■^-Nitrohenzohornylainide.

Solvent. p. [o]^'.

Ethyl alcohol 4-2770 -16-75°

Methyl alcohol 5-0035 -13-44

Glacial acetic acid 3-8347 -7-28

Pyridine 4'7106 +26-41

,, 9-9493 +22-80

[M]'f.

Mol. .sol. vol,

-84-29°

_

-74-35

241-0 c.c.

-36-72

251-0 „

+ 82-20

250-5 ,,

+ 66 -92

252-5 ,,

[M]'f'.

Mol. .sol. vol.

-50-58°

—

-40-59

247-5 c.c.

-21-98

251-2 ,,

+ 79-76

250-1 „

+ 68-86

252-1 ,,

2028

FRANKLAND AND BARROW

Hcnzoboi

nylainidc.

Toluobornylamides.

P

[MJrr-

^

P

r

^

Solvent.

(approx.

). [M]f.

(approx. ).

Ortho-. Meta-.

Para-.

Ethyl alcohol

5

-58-93°

2-5

-50-24° -57-75°

-36-23

? ) ) ) ......

10

-62-63

5-0

-51-60 -60-70

-39-43

Methyl alcohol ...

5

-57-44

2 0

-46-12 -55-20

-3301

J* )? • • •

10

-59-88

4-0

-46-10 -58-54

-33-90

Glacial acetic acid

5

-26-14

5-0

-2813 -22-09

- 1 -33

M if ! '

10

-29-94

10-0

-30-73 -24-34

-4-09

Pyridine

5

+ 66-67

5 0

+ 30-38 +72-90

+ 82-93

10

+ 59 -OS

10-0

+ 27-75 +62-45

+ 74-23

It will be observed that the rotatory power of the bornylamides
of these aromatic acids is influenced by the nature of the solvent
and the concentration in a similar manner to that of the aliphatic
bornylamides already described in the previous communication.
It was pointed out, in dealing with the latter compovmds, that they
were of very much lower negative rotation in pyridine than in
methyl-alcoholic solution. This is again found to be true for the
aromatic bornylamides; but, owing to the greater effect of the
solvent, the change from methyl alcohol to pyridine is accompanied
in all these compounds, -with the exception of o-nitrobenzobornyl-
amide, by a complete reversal in the sign of the rotation — the
rotatory power in the former solvent being negative, and in the
latter positive. It will also be observed that the rotatory powers
preserve the same order in the different solvents as in the case of
the aliphatic bornylamides, the values in acetic acid solution lying
between those in pyridine and methyl-alcoholic solution.

The rotatory power of the aromatic bornylamides is affected by
the concentration in a similar manner to the other acyl-bornyl-
amides, the rotations becoming greater, in a negative sense, as
the concentration increases. Bearing on this variation in the
rotatory power with the concentration, it is worthy of note that in
glacial acetic acid solution of concentration 2^ = 10, jj-toluobornyl-
amide has a molecular rotation of — 4'09, whilst in one per cent,
glacial acetic acid solution it is completely inactive.

Turning to the influence of temperature on the rotation of the
uitrobenzobornylamides, it is found that as a general rule increase
in this factor results in a diminution of rotatoi-y power, as may
readily be seen from the accompanying diagram.

It -nail only be necessary here to indicate the following points.
Firstly, in pyridine solution, the rotatory powers of the three uitro-
benzobornylamides diminish in a positive sense at about the same
rate. This, of course, necessitates that the laevorotation of the
ortho-compound increases with rise of temperature. Secondly, the
negative rotations in methyl-alcoholic solution also diminish as the

THE ACYL-BORNYLAMINES. PART II.

2029

temperature increases. Thirdly, whilst the laivorotation of the
meia- and para-nitrobenzobornyhiinides in glacial acetic acid solu-
tion decreases uniformly as the temperature rises, that of the
ortho-isomcride is scarcely affected, the rotation at 16"5° being
practically identical with the value found at 44°.

Molecular rotation of the nitrohenzohornylamidcs in pyridine, methyl alcohol, and
acetic acid solution.

30° 35°

Temperature.

N.B.— In order to shorten the diagram the ordinates from 0° to +40° have been

omitted.

In several respects the o-nitrobenzo-compound is abnormal in its
behaviour. In the first place, the rotatory powers in pyridine are
negative, whilst those of the corresponding meta- and para-
compounds are positive. Further, it is strongly marked off from
the isomeric nitrobenzobornylamides in possessing a lower laevo-

VOL. xcv. 6 s

2030 FRANKLAND AND BARROW:

rotation in ethyl alcohol than in methyl-alcoholic solution. It also
differs from the isomeric compounds by showing, as we have just
seen, practically no variation of rotatory power with increase of
temperature in glacial acetic acid solution.

In connexion with this abnormality in the optical behaviour of
o-nitrobenzobornylamide, it is worthy of note that, of the three
isomerides. this has the highest melting point, and thus exhibits
the exceptional phenomenon of an ortho-compound melting at a
higher temperature than the corresponding para-derivative.

The only active compounds containing the three isomeric nitro-
beuzo-groujjs which have up to the present been investigated are
the uitrobenzoyl-^-carvoximes, the methyl and ethyl esters of the
dinitrobenzoyltartaric acids, and the menthyl nitrobenzoates ; and
in these cases also, the ortho-compounds show an abnormal
behaviour as compared with the meta- and para-isomerides. The
rotations obtained for these compounds have been collected in the
tables given on pp. 2033, 2034.

From the values there given, it will be observed that, with the
nitrobenzoyl-rf-carvoximes, this abnormality of the ortho-compound
manifests itself in the complete absence of rotatory power, although,
from analogy to other position-isomeric active compounds, it would
be anticipated that, in this case, the ortho-derivative should have
the highest dextrorotation of the three. The inactivity cannot be
explained by racemisation, since, on hydrolysis, a dextrorotatory
and not an inactive carvoxime was obtained. The rotation of the
o-nitrobenzoyl compound appears, however, to have been investigated
at two concentrations, which did not differ materially from one
another; and, just as ;p-toluobornylamide in glacial acetic acid
solution at a particular concentration and temperature was found
by us to be inactive, so the exceptional value found by Goldschmidt
and Freund for the rotation of o-nitrobenzoyl-f/-carvoxime may be
due to its having been examined in such a solvent, and under such
conditions of temperature and concentration that the activity of
the compound was completely suppressed. It is, moreover, worthy
of note that the authors mention that at the temperature of solid
carbon dioxide the chloroform solution did exhibit a very feeble
rotation.

In the case of the ethyl dinitrobenzoyltartrates (P. F. Frankland
and Harger, Trans., 1904, 85, 1571), the rotation of the ortho-
compound has such a very large temperature-coefficient that, at high
temperatures, it is less, and at low temperatures greater, than the
rotation of its isomerides, and the same appears to be also the case
for the methyl ester (P. F. Frankland and Harger, loc. cit.),
concerning which, however, the data are not so complete.

THE ACYL-BORNYLAMINES. PART II. 2031

The isomeric mentliyl nitrobenzoates of Cohen and Armes (Trans.,
1905, 87, 1190) also show the ortho-compound to possess certain
exceptional features with regard to its rotation, more especially in
the magnitude of its temperature-coefficient.

It was thought that this difference in the behaviour of the ortho-
compound might be due to its possessing a different constitution
from the meta- and para-compounds, and, with the view of testing
this supposition, we made a large number of observations on
the refractive power of the nitrobenzobornylamides in solution,
which, however, failed to throw any light on this point. The
molecular refraction of these compounds varies with the solvent
in very much the same manner for each, ortho-uitrobenzobornyl-
amide showing no marked difference from the meta- and
para-isomerides.

It has been pointed out from theoretical considerations
(Frankland and Wharton, Trans., 1896, 69, 1309, 1583) that, in
the case of isomeric di-substituted benzene rings, the para-isomeride
should exert the greatest influence on the rotation, and the ortho-
the least, whilst the influence of the meta-isomeride shovild be inter-
mediate between that exerted by the ortho- and para-compounds
respectively; it has, however, also been shown that the methyl and
ethyl dinitrobenzoyltartrates (P. F. Frankland and Harger, loc. cit.)
give exceptional values for the ortho-compound, and similar excep-
tional results have been obtained in the case of the nitrobenzoyl-
c?-carvoximes (Goldschmidt and Freund, loc. cit.), the /3-methyl-
adipotoluidides (Rawitzer, Thesis, Zurich, 1896, 25 ; Guye, Bull.
Soc. cliim., 1896, [iii], 15, 1158), and more recently in that of the
hydroxy- and methoxy-benzylidenecamphors (Haller, Comvt. rend.,
1891, 113, 22; Haller and UixWev, ibid., 1899, 128, 1370; Haller
and Bauer, ihid., 1909, 148, 1490).

The observations which we have made on the rotatory powers of
the nitrobenzo- and toluo-bornylamides do not, however, support
the general rule. It will be seen, on reference to the tables given
on pp. 2036 and 2042, that the relationship between the rotatory
effects of position-isomeric groups depends to a very great extent
on the solvent in which the compounds are examined.

Of the isomeric nitrobenzobornylamides, the ortho-compound has
in all solvents a greater Icevorotation than the para-isomeride, but
T/t-nitrobenzobornylamide occupies every possible position with
respect to the isomeric compounds. Thus, in methyl and glacial
acetic acid solutions, as well as in pyridine solution of concentration
-p — lQ, the rotations of the nitrobenzobornylamides exhibit the usual
order, namely, ortho, meta, para; in ethyl-alcoholic solution, the
order of the rotatory effects is meta, ortho, para ; whilst in pyridine

6 S 2

2032 FRANKLAND AND BARROW:

solution of concentration p — 5, the rotations show the order, ortho,
para, meta.

The rotatory effects of the toluoyl groups are, on the whole, not
so erratic as those of the nitrobenzoyl groups. In both glacial
acetic acid and pyridine solutions, the rotations of the toluobornyl-
amides stand in the order predicted from theoretical considerations,
but in methyl- and ethyl-alcoholic solutions the rotatory power
of the ortho-isomeride is intermediate between those of the meta-
and para-compounds respectively.

The molecular rotations of the nitrobenzo- and toluo-bornyl-
amides enable us to compare the rotatory effect of the methyl and
nitro-groups when substituted in the ortho-, meta-, and para-
positions of the benzene ring respectively. The comparison is,
however, rendered difficult owing to the large variations in the
rotations induced by solvents.

Introduction of the nitro-group in the jDara-position of the
benzene ring exerts, in all solvents, a dextrorotatory influence on the
rotation of benzobornylamide ; a similar but more pronounced effect
is also produced by the para-methyl group. Substitution with the
nitro-group in the ortho-position exerts a Isevorotatory influence in
all solvents employed, and the same is also true in the case of the
methyl group in acetic acid and pyridine solutions; in methyl- and
ethyl-alcoholic solutions, on the other hand, the introduction of the
methyl group in the ortho-position is accompanied by a dextro-
rotatory influence.

In the meta-position, introduction of the methyl gi'oup produces
comjDaratively little influence on the rotation of benzobornylamide,
whereas the nitro-group in the same position exerts, in all solvents
with the excejjtion of pyridine, a marked Igevorotatory influence.

The influence of the methyl and nitro-groups on the rotation
of benzobornylamide may be readily compared by means of the
following table, in which their rotatory effects in the various
positions of the benzene ring are contrasted :

Influence of Methyl and Nitro-grou'ps on the Molecular' Rotation,
[M]d°, of Benzohornylamide.

Ortho-. Meta-. Para-.

Solvent.

CH3.

NO.,.

CH3.

NO2.

CH3.

NO2.

Ethyl alcohol

+ 7-3°

-8-7°

-l-S"

-25-4°

+ 19-5°

-f8-3'

Methyl alcohol ...

+ 11-3

-34-1

-1-1

-16-9

-f23-5

+ 16-8

Glacial acetic acid

-20

-14-7

-t-4-0

-10 5

+ 24-8

+ 4-2

Pyridine, jo = 5 ...

-36-3

-84-4

+ 6-2

-fl5-6

-M6-3

+ 13-1

;>=10... -31-3 -82-2 -t-2-9 +7-9 -H5-2 +9-8

In connexion with the rotatory effect of the methyl and nitro-
groups, the above results may be compared with those obtained in

THE ACYL-BORNYLAMINES. PART II.

2033

other series by means of the tables given belo-w, in which the data
so far available for effecting a comparison of the rotatory inflvxences
of the two groups in all three positions of the benzene ring have
been collected :

A cyl-d-carvoxivies*
Rotation in Chloroform, Solution.

p. f- [M]^. p. e. imt

o-Nitrobenzoyl 4-7044 20-0° O-QO" benzoyl 9-1058 18-5 +71-66°

4-5575 ,, 0-00 o-Tohioyl 9-1942 15*5 +76-64

7n.-Nitrobenzoyl 4-5845 23-5 +64-94 m-Toluoyl 10-0169 15-5 +76-01

p-Nitrobenzoyl 4-5648 22-5 +54-42 ;3-Toluoyl 9-2950 15-5 +66-34

* Goldschraidt and Freund (Zcitsch. physikal. Chem., 1894, 14, 394).

Diethyldiact/llartrates.
Ethyl diiiiti-ol)enzoyltartrates.-|- Ethyl ditcluoyltartrates.:

f.

20°
100
135
180

Ethyl

dibeuzoyl-

tartrate.*

-247-0°

251-6

235-5

215-0

Ortho.

- 651 -2°
315-8
214-9
117-3

Meta.
-357-3°
324-3
298-4
248-5

Para.
-638-9°
490-0
430-8
340-1

Ortho.

-266-8°
241-9
222-6

Meta.

-306-0°

381-7

281-7

Para.

397-7*
362-0
311-0

* Frankland and Wharton, Trans., 1896, 69, 1583.
t Frankland and Harger, Trans., 1904, 85, 1571.
% Frankland and Wharton, Trans., 1896, 69, 1309.

180

Dimethyldiacyltartrates.

Methyl
dibenzoyl-
tartrate. *

diethyl dinitrobenzoyltartrates. f

, '• ,

Ortho. Meta. Para.

Methyl ditcluoyltartrates. J

f.

Ortho. Meta. Para.

20°

—

— -379-1° —

-324-3° — —

100

-280-1°

[- 466-3°] § 329-5 -512-0°

282-3 -327-1° -425-7°

135

259-2

- 429-9 "]§ 296-4 444-3
_ «=109°_

255-0 293-1 378-9

225-5

253-5

363-4

220-8

254-9 322-2

t Frankland and Harger, loc. eit.

* Frankland and Wharton, loc. cit.

X Frankland and Wharton, loc. cit.

§ The values enclosed in brackets are only approximate, for no density deter-
minations of dimethyl di-o-nitrobenzoyltartrate were made, the corresponding
densities of the meta-compound having been used for the approximate calculation of
the molecular rotation.

2034

FRANKLAND AND BARROW

Menthyl Esters.

Jlenthj'l nitrobenzoates, [M]J^".

e.

Ortho.

Meta.

I'ara.

100*

-370-0°

-250-3°

-230-0'

80

380-6

253-4

232-2

70

379-3

252-2

233-5

65

380-1

251-1

234-7

20

—

252-2

—

Menthyl- f. [M]„.

Benzoate-f 20°t -263-3°§

0-Toluat.et 20 231-3

OT-Toluatet 20 241-0

;)-Toluatet 20 252-5 §

* Cohen and Amies, Trans., 1905, 87, 1190.
t Tsehugaeff, Ber., 1898, 31, 1775.

J The temperature of observation was presnmahly 20° in each case, as the density
is given for that temperature for the o- and 9H.-compounds.

§ l!i)tation in benzene solution, all the other values being for the liquid state.

The comparison of the rotatory effects of the methyl and nitro-
groups may also be instituted by means of the three tartarodi-
tohiidides and the three nitroanilides respectively. The tartaro-
dinitroanilides have been prepared and polarimetrically examined
by one of ixs in conjunction with Miss M. B. Thomas, and the
results, a summary of which is given below, will form the subject
of a future communication.

Rotation in Pyridine Solution.

Tartarodianilide *

P-
1-820
5-421

+ 737
+ 740

Tartarodi-

o-Nitroanilide 2

2

m-Nitroanilide 2

3
1
2

P-

p-Nitroanilide

676
894
197
261
688
158

[M]f.

+ 375°

375

768

764

1072

1069

Tartarodi-

P-

o-Toluidide* 3-012

4-994

?n-Toluidide* 2-153

6-65

^5-Toluidide* 3-885

4-502

Frankland and Slator, Trans,, 1903, 83, 1349.

[M]7.

+ 653°
667
710
713
790
790

Experimental

Benzohornylamide.

Twelve grams of bornylamine hydrochloride were dissolved in
water, and the free bornylamine precipitated by the addition of an
excess of a dilute aqueous solution of potassium hydroxide. The
amine was dissolved by the addition of ether, and a little more than
the calculated amount of benzoyl chloride in ethereal solution
slowly run in, the mixture being well agitated in order to decompose
the bornylamine hydrochloride formed in the reaction. On

THE ACYL-BORNYLAMINES. PART II. 2035

evaporation of the ethereal solution, benzobornylamide is left
behind in small, colourless needles, which, on rccry^stallisation from
dilute alcohol, melt at 138-5°. It is readily soluble in pyridine,
acetic acid, or alcohol :

0-3020 gave 14-3 c.c. No (moist) at 14° and 759 mm. ISr = 5-56.
C1-H23ON requires N = 5-45 per cent.

Rotatory Power of Benzohornylamide.

p. ^2074°. Immm. a-^'. [o]^. [M]'f.

Ethyl-Alcoholic Solution.

4-9940
9-9747

0-8017
0-8128

389-9 -3-58°
199-84 3-95

-22-93°
24-37

-58-93°
62-63

Methyl- Alcoholic Solution.

5-0013
10-0079

0-8054
0-8177

389-9 -3-51*'
199-84 3-81

-22-35'
23-30

-57-44°
59-88

Glacial Acetic Acid Solnt

ion.

5-0055
10-0524

1-0535
1-0550

389-9 -2-09°
199-84 2-47

Pyridine Solution.

-10-17°
11-65

-26-14°
29-94

5-0151
9-9567

0-9817
0-9864

389-9 +4-98°
199-84 4-51

+ 25-94°
22-98

+ 66-67°
59-06

The value given above for the rotatoi'y power in ethyl-alcoholic
solution is slightly greater than that found by Forster, namely,
[a]f -21-8°, 0 = 4-0052.

o-Nitrohenzohornylamide.

This was prepared from 12 grams of bornylamine and the
theoretical amount of o-nitrobenzoyl chloride in ethereal solution
(150 — 200 c.c), in a similar manner to that employed in the case
of the benzo-derivative. After some time, the greater part of the
amide crystallises out, whilst from the ethereal solution the remain-
der is obtained on evaporation. It was recrystallised from dilute
alcohol until of constant rotatory power :

0-1459 gave 12-0 c.c. No (moist) at 13-0° and 737-5 mm. N = 9-41.
CjyHooOsNo requires N = 9-27 per cent.

o-Nitrohenzohormjlamide crystallises in colourless, prismatic
needles, melting at 173°. It is readily soluble in pyridine or
chloroform, moderately so in alcohol, and less soluble in ether.

2036 FRANKLAND AND BARROW :

Rotatory Power of o-Nitroh enzohornylainide.
Ethyl-A Icoholic Solution.

Density

°f

p-

20°/4°.

Z = 389-9 mm.

[«]f.

[M]f.

4-9799

0-8049

-3-50°

-22-39°

-67-62°

Methyl- Alcoholic Solution, 2>~ 5-0654.

Density

"u

Temperature. «°/4°.

^■-=389-9 iiini.

["]::•

[M]^

20-0° 0-8067

-4-83°

-30-32°

-91-57°

26-0 0-801-2

4-70

29-70

89-69

31-0 0-7965

4-59

29-18

8812

37-5 0-7903

4-47

28-64

86-49

45-0 0-7831

4-31

27-87

84 16

De7isities determined :

Temperature

20°

25°

35°

45°

Density i'/r

0-8067

08020

0-7928

0-7831

Glacial Acetic Acid Solution, p = 3'9454.

Densitj' a'°

Temperature. tyi". Z = 389 -9 mm. [a]'^. [MJJ^.

16-5° 10598 -2-24° -13-74° -41-49°

20 0 10565 2-20 13-54 4089

29-0 1-0466 2-18 13 54 40-89

44-0 1-0300 2-14 13 51 40-80

Densities determined :

Temperature 20° 25° 35°

Density r/4° 1-0565 1-0511 1-0400

Pyridine Solution, 2^ = 5-0011.

Density
Temperature. r/4°.

^ = 389-9 mm.

^<-

mt

20-0°
25-0
30-0
38-5
45-5

Densitiei

0-9860
0-9810
0-9760
0-9678
0-9608

f determined :

-1-13°
1-24
1-35
1-60
1-78

-5-88°
6-48
7 09
8-48
9-50

-17-76'
19-57
21-41
25-61
28-69

Temperature

Density r/4°

20°
0-9860

25°
0-9810

35°

0-9713

45°
0-9613

THE ACYL-BORNYLAMINES. PAUT II.

2037

Fyridme Solution, 2? = 10-087.

Teinpi'iature.

20-0°
25-5
32-0
39 0

45-0

Density

r/4°.

0-9949
0-9896
0-9836
0-9766
0-9707

Densities determined :

Temperature

Density <°/4°

Z = 389

-3
3
3
3
3

20°
0-9949

9 mm.

00°
22
45
62

78

0-9901

[<■

mt

-7-67°

-2316°

8-27

24-97

8-92

26-94

9-43

28-48

9-90

29-90

35°

45°

0-9806

0-9707

VdrN itrob enzoh ornylamide.

The preparation of this compound was accomplished by the
interaction of bornylamine (12 grams) and the theoretical amount
of m-nitrobenzoyl chloride in ethereal solution (150 c.c), in exactly
the same way as that described for the benzo-compound. The
greater portion of the amide crystallised out from the ethereal
solution after some time. Purification was effected by recrystal-
lisation from dilute alcohol :

0-1423 gave 11-6 c.c. N2 (moist) at 15° and 746-5 mm. N = 9-36.
C17H22O3N2 requires N = 9-27 per cent.

ria.-Nitrohenzohornylamide crystallises in almost colourless needles,
melting at 161° without decomposition. Its solubility in the
ordinary solvents is less than that of the corresponding ortho- and
para-compounds.

Eotatory Voxver of xn-Nitrohenzohornylamide.
Ethyl- Alcoholic Solution.

Density

a'^'

p-

20°/4°.

Z = 389-9 mm.

[a]f.

[M]f.

2-6399

0-7972

-2-29°

-27-91°

-84-29

Methyl-Alcoholic Solution, 2^ = 1'9190.

Density
Temperature. f°/4°.

<
Z = 389-9 mm.

\.<-

[M]^.

20-0° 0-7979
250 0-7930
30-5 0-7880

-1-47°
1-44
1-34

-24-62°
24-27
22-73

-74-35'
73-29
68-64

Densities determined :

Temperature

20=
0-7979

25°
0-7930

35°

Density fji°

0-7838

2038

FRANKLAND AND BARROW:

Glacial Acetic Acid Solution, 2? = 3-8987.

Temperatme.

20-0°
25-5
34-0
40-5
47-5

Density
tyi".

1-0548.
1-0505
1-0408
10335
1-0256

Z=389-9 mm.

-1-95°
1-78
1-58
1-38
1-20

-12-16°

11-15

9-99

8-78

7-70

-36-72°
33-67
30-17
26-52
23-25

Densities determined:

Temperature
Density r/4°

20°
1 -0548

25°
1-0509

35°
1-0398

45°

1-0286

Pyi'idine Solution

p = 5-0079.

Temperature.

Density
r/4°.

<
Z = 389-9 mm.

[«]'„•

[M]'„.

20-0°
25-0

31-0
40-5

0-9860
0-9811
0-9751
0-9658

+ 5-24°
5-16
4-94
4-66

+ 27-22°
26-94
25-95
24-71

+ 82-20°
81-36
78-47
74-62

Densities det

tr mined :

Temperature
Density <°/4°

20°
0-9860

25°
0-9811

35°
0-9713

45°
0-9613

Pyridi

ne Solution

, 2? = 9-9862.

Temperature.

Density

r/4°.

<
Z=199-84 mm.

[»]L-

[M]^:.

17-0°

20-0

25-5

30-5

38-5

45-5

0-9978
0-9948
0-9897
0-9848
0-9771
0-9702

+ 4-50°
4-40
4-27
4-17
4-00
3-88

+ 22-60°
22-16
21-62
21-22
20-51
20-04

+ 68-25°
66-92
65-29
64-08
61-94
60-52

Densities determined :

Temperature
Density <°/4°

20°
0-9948

25°
0-9901

35"
0-9805

45°

0-9707

p-Nitrobenzobornylamide.

The method of preparation was the same as that employed in the
case of the preceding compounds, enough ether being used to keep
the whole of the amide in solution. The product obtained by
evaporating the ethereal solution was purified by recrystallising
from dilute alcohol :

0-1452 gave 11-6 c.c. Ng (moist) at 14° and 756 mm. N = 9-35.
C17H22O3N2 requires N = 9'27 per cent.

p-Nitrob enzobornylam/ide crystallises in long, slender needles of

THE ACYL-BORNYLAMINES. PART II.

2039

a pale yellow colour, melting at 167°. It is readily soluble in
pyridine, and moderately so in alcohol or acetic acid.

'Rotatory rower of p-Nitrohenzohornylamide.
Ethyl-Alcoholic Solution.

Density

"■T

p-

20°/4°.

Z = 389-9 mm.

[«]r

[MJf.

•1933

0-8017

-2-17°

-16-56°

-50-01

•2770

0-8020

2-24

16-75

50-58

Mfthyl-Alcoliolic Solution, 77 = 5'0035.

Density
Temperature. t°li°.

Z = 389-9 mm.

["]'J-

[M]^.

20-0° 0-8085
25-0 0-8040
35-0 0-7951

-2-12°
1-96
1-70

-13-44°
12-49
10-96

-40-59
37-72
33-10

Densities determined :

Temperature...

Density ^74°

20°
0-8085

25°
0-8040

35°
0-7951

Glacial Acetic Acid Solution, p = 3"8347.

Density

«n

Temperature. t'l^^".

Z = 389-9 mm.

[«];■•

[M];.

20° 1 -0565

-1-15°

-7-28°

-21-98'

25 1-0512

1-03

6-55

19-78

29 1 -0465

0-90

5-76

17-39

34 1-0410

0-78

5-01

15-13

40 1-0343

0-58

3-75

11-32

46 1 -0274

0-42

2-74

8-28

Densities determined :

Temperature

20°

3.5°

45°

Density ^74°

1-0565

1-0397

1-0286

Pyridine Solution, p = 4"7106.

Density

"',

Temperature.

t^li\

Z = 389-9 mm.

[<■

[M];;.

16-5°

0-9888

+ 4-85°

+ 26-71°

+ 80-66°

20-0

0-9855

4-78

26-41

79-76

25-5

0-9801

4-63

25-71

77-64

34-0

0-9717

4-36

24-45

73-84

42-0

0-9638

4-18

23-61

71-30

Densities determined :

Temperature

20°

25°

35°

45°

Density <°/4°

0-9855

0-9806

0-9708

0-9609

2040 FRANKLAND AND BARROW:

Pyridine Solution, p = 9-9493.

Density

Temperature. <°/4°.

20° 0-9949
27 0-9881
35 0-9804

Z = 199-84 mm.

+ 4-51°
4-42
4-23

+ 22-80°
22-50
21-70

+ 68-86
67-95
65-53

Densities determined:

Temperature

Density f/4°

20°
0-9949

25°
0-9902

35°
0-9804

0-Toluohornylamide.

The mode of preparation was similar to that adopted in the case
of the nitrobenzo-compounds. The product left after distilling off
the ether -was crystallised from a mixture of benzene and light
petroleum until of constant rotatory power :

0-2963 gave 13-1 c.c. Ng (moist) at 9° and 756 mm. N = 5-28.
CjgHosON requires N = 5-17 per cent.

o-T ol u oh ornyl amide crystallises in colourless needles, melting at
97 — -98°. It is readily soluble in benzene, acetone, or pyridine, and
only slightly soluble in light petroleum.

Rotatory Power of o-Toliu)hornylamide,

p. d. 20°/4°. Zinmm. af. [a]^\ [M]^'.

Ethyl-Alcoholic Solution.

2-5037
5-0002

0-7956 389-9 -1-44°
0-7999 389-9 -2-97

Methyl- Alcoholic Solution.

-18-54°
-19-04

-50-24°
-51-60

1-9986
4-0052

0-7991 389-9 -1-06
0-8016 389-9 -2-13

-17-02
-17-01

-46-12
-46-10

Glacial Acetic Acid Solution.

5-0307
9-9783

1-0508 389-9 -2-14
1-0521 199-84 -2-38

Pyridine Solution.

-10-38
-11-34

-28-13
-30-73

4-9955
9-9977

0-9804 389-9 +2-14
0-9845 389-9 +3-93

+ 11-21
+ 10-24

+ 30-38
+ 27-75

m.-Toluobornylamide.

This was prepared in the usual manner by the interaction of the
acid chloride and bornylamine in ethereal solution, and purified
by crystallisation from dilute alcohol :

THE ACYL-BORNYLAMINES. PART II. 2041

0-2954 gave 13-2 c.c. No (moist) at 14-5° and 756 mm. N = 5-20.
CjgHgaON requires N = 5-17 per cent.

vd-Toluohornylamide crystallises in fine, silky needles, melting at
140 — 141°. It is easily soluble in pyridine or glacial acetic acid,
and moderately so in alcohol.

Rotatory Voxvtr of m.-T()luohornylamide.

p. rf. 2074°. Zinnim. af. [ajf- [M]f,

Ethyl-Alcoholic Solution.

2 -.^032
5-0073

0-7932
0-8003

389-9 -1-65°
389-9 -3-50

M ethyl- Alcoholic Solution.

-21-31°
-22-40

-57-75"
-60-70

2 0004
4-0056

0-7994
0-8033

389-9 -1-27
389-9 -2-71

-20-37
-21-60

-55-20
-58-54

Glacial Acetic Acid Solution.

5-0038
10-0215

1-0506
1-0513

389-9 -1-67
199-84 -1-89

Pyridine Solution.

-8-15
-8-98

- 22-09
-24-34

4-9922
10-0080

0-9816
0-9850

389-9 +5-14
199-84 +4-54

+ 26-90
+ 28-05

+ 72-90
+ 62-45

^-Toluohoi'nylamide.

This was prepared from j^-toluoyl chloride and bornylamine in
the same manner as that employed in the case of the preceding
compounds. On evaporating the ether, a theoretical yield of the
amide was obtained. It was purified by recrystallising from dilute
alcohol until of constant rotatory power :

0-3043 gave 14-0 c.c. Ng (moist) at 13° and 741 mm. N = 5-29.
CjgHosON requires N = 5-17 per cent.

Tp-Toluobo?'nylamide crystallises in colourless, prismatic needles,
melting at 169° without decomposition. Like the isomeric amides
described above, it is readily soluble in pyridine or glacial acetic
acid. At the ordinary temj^erature it gives only about a 4 per
cent, solution in methyl alcohol.

■lO-i'l HOPE AND PERKIN : ETHYL BENZOYLACETATE.

Rotatory Power of p-Toluohornylamide.
p. (^.2074°. Ziumm. af. [a]f. [M]f.

Ethyl- Alcoholic Solution.

2-4839 0-7956 389-9 -1-03° -13-37° -36-23°

5-0187 0-8010 389-9 -2-28 -14-55 -39-43

Methyl-Alcoholic Solution.

2-0026 0-7989 389-9 -0-76 -12-18 -33-01

4-0036 0-8038 389-9 -1-57 -12-51 -33-90

Glacial Acetic Acid Solution.

1-0010 1-0501 389 9 ±00 ±0-0 ±0-0

5-00-22 1-0508 389-9 -0-10 -0-49 -I'SS

10-0130 1-0519 389-9 -0-62 -1-51 -4-09

Pyridine Solution.

5-0064 0-9810 389-9 +5-86 +30-60 +82-93

7-9320 0-9835 389-9 +8-83 +29-03 +78-67

10-0225 0-9842 199-84 +5-40 +27-39 +74-23

University,

Birmingham.

CCXXIII. — Ethyl Benzoylacetate.

By Edward Hope and William Henry Perkin, jun.

Ethyl benzoylacetate was discovered by Baeyer in 1882 {Ber.,
15, 2705), and the first investigations of this important substance
and of many of its derivatives are described in several papers
published between this date and 1886.* The ester had, at that
time, to be prepared by the action of concentrated sulphuric acid
on ethyl phenylpropiolate, a process which not only yielded an
impure product, but was at the same time so laborious that
experimental investigation could only be carried out with very
small quantities of material. Ethyl benzoylacetate is now a
commercial substance, and, during the covirse of some recent
experiments with the pure ester, we were led to the conclusion
that some of the statements in the original papers, made more
especially in connexion with the substitution derivatives, were
incorrect, and that others required modification. Ethyl benzoyl-

* Baeyer and Perkin (Ber., 1883, 16, 2128) ; Perkin (Trans., 1884, 45, 170 ; 1885,
47, 240, 262) ; Perkin and Caiman (Trans., 1886, 49, 154) ; Perkin and Bellenot
(Trans., 1886, 49, 440).

HOPE AND PERKIN : ETHYL BENZOYLACETATE. 2043

acetate is readily converted into such mono-substitution products
as ethyl a-benzoylpropionate, CcHj'CO'CHMe'CO^Et, and ethyl
a-benzoylbutyrate, C^Hj-CO'CHEt'COoEt, by treatment, in alco-
holic solution, with sodivim ethoxide and the alkyl iodide, the
process being exactly similar to that commonly employed in pre-
paring substitution derivatives of ethyl acetoacetate.

Disubstitution derivatives of ethyl benzoylacetate, such as ethyl
a-benzoyl/.?obutyrate, CcHr,*CO'CMe2*C02Et, and ethyl a-benzoyl-
a-ethylbutyrate, CgHs-CO'CEto-COoEt, unlike those of ethyl
acetoacetate, can either not be prepared at all, or only in very
small yields, by treating the mono-substituted ester with sodium
ethoxide and the alkyl iodide in alcoholic solution. On the other
hand, such disubstitution derivatives may be obtained in the
absence of alcohol, namely, by acting, for example, on the toluene
solution of the mono-substitution derivative, first with sodium, and
then with the alkyl iodide. Under these conditions, ethyl a-benzoyl-
isobutyrate is obtained in a yield of at least 60 per cent, of that
theoretically possible (p. 2046), but, on the other hand, it is remark-
able that the introduction of the second ethyl group into ethyl
a-benzoylbutyrate takes place with much more difficulty, and the
yield of disubstitution derivative does not, as far as can be judged,
exceed 20 per cent, of that theoretically possible.

There can be no doubt that the explanation of this discrepancy
is to be sought in the greater reactivity of methyl iodide, and,
in support of this view, we find that the yield of ethyl a-benzoyl-
a-methylbutyrate, C6H5'CO*CMeEt'C02Et, is gi'eater when methyl
iodide reacts in toluene solution with the sodium derivative of
ethyl a-benzoylbutyrate than when ethyl iodide reacts with the
sodium derivative of ethyl a-benzoylpropionate. Again, it is well
known that benzyl chloride is very reactive, and, in accordance with
the above explanation, we find that the sodium derivative of ethyl
o-benzoylbutyrate reacts readily with benzyl chloride, and the yield
of ethyl o-benzoyl-;8-phenyl-a-ethylpropionate,

CeHs'CHo-CEtBz-COoEt,

obtained is at least 60 per cent, of that theoretically possible.

These results are at variance with the earlier work' of Perkin
(Trans., 1884, 45, 182), in which it is stated that ethyl benzoyl-
diethylacetate (ethyl a-benzoyl-a-ethylbutyrate) is produced when
ethyl benzoylethylacetate (ethyl a-benzoylbutyrate) is treated with
sodium ethoxide and ethyl iodide in alcoholic solution. The
product was not purified by fractional distillation, but the di-
substitution derivative must have been formed, because the ester
yielded diethylacetophenone on hydrolysis; unfortunately, there is
no record of the amount of this latter substance which was

204-i HOPE AND PERKIN : ETHYL BENZOYLACETATE.

obtained. Discrepancies sucli as this, which one of the authors
(P) and others have repeatedly noticed, especially in cases of this
kind, must be due to slight differences in the conditions of experi-
ment, and very probably to the presence or absence of varying
quantities of moist vire in the alcohol and other materials employed.
The second point, which we have carefully investigated and deal
with in detail in the present communication, is the behaviour of
the substitution derivatives of ethyl benzoylacetate on hydrolysis.
It was early recognised (Trans., 1885, 47, 242) that ethyl benzoyl-
acetate itself is readily hydrolysed by concentrated sulphuric acid
in the cold, with formation of benzoylacetic acid, but this simple
method did not apply to the mono- or di-substitution derivatives,
which, under these conditions, either remained unchanged or were
hydrolysed with elimination of carbon dioxide and formation of
substitution derivatives of acetophenone, and these results we can
confirm. Experiments on the action of alcoholic potassium
hydroxide under different conditions 'on the mono- or di-sub-
stitution derivatives of ethyl benzoylacetate yielded unsatisfactory
results, since the products, which we were able to isolate, were
usually only benzoic acid and substituted acetophenones.

On the other hand, dilute potassium hydroxide (3 per cent.)
gradually dissolves the mono-substitution derivatives of ethyl
benzoylacetate, and, after remaining for two days and then acidify-
ing and extracting with ether, the mono-substituted benzoylacetic
acid is obtained. We have thus prepared a-benzoylpropionic acid
(m. p. 82 — 83°) and a-benzoylbutyric acid (m. p. 85 — 87°) in a
pure state.

The disubstitution derivatives of ethyl benzoylacetate are
insoluble in dilute alkalis, and we have been unable to find any
conditions which yield the corresponding acids. In all experiments
where hydrolysis took place, it was accompanied by the simultaneous
elimination of carbon dioxide and formation of substituted aceto-
phenones and benzoic acid. The melting points of benzoyl-, ethyl-,
allyl-, and diethyl-acetic acids (a-benzoyl-butyric, -allylacetic, and
-a-ethylbutyric acids) given in the earlier paper (Trans., 1884, 45,
180) as 115°, 122°, and 128—130°* respectively are incorrect.
There can be no doubt that the acids were produced in the way
described, but, unfortunately, the final melting points were not
taken until several months after the analyses had been made, and
while the results were being written for publication ; during this
time decomposition had evidently taken place, in each case with

formation of benzoic acid.

•

* This should have been 118—120°.

HOPE AND PERKIN : ETHYL BENZOYLACETATE. 2045

Experimental.

Ethyl a-Benzoyljvnpionate, CcHj-CO-CHMe-COoEt, Ethrjl a-Benzoyl-

isohutyrafe, CeHy-CO'CMco'COoEt, and Efliyl a-Benzoxjl-^-fhenyl-

isoftw^ym^e/CeHVcHg-CMeBz-COoEt.

Ethyl a-benzoylpropionate has already been described Ijy Perkin
and Caiman (ethyl benzoylmethylacetate : Trans., 1886, 49, 156)
as a colourless oil boiling at 235°/ 300 mm. We have prepared
considerable quantities of this ester by mixing ethyl benzoylacetate
(30 grams) with sodium ethoxide (containing 3'6 grams of sodium),
adding methyl iodide, and heating on the water-bath for one hour.
It distilled at 162 — 163°/ 18 mm., and yielded correct results on
analysis :

01165 gave 0-2976 COo and 0-0731 HoO. C = 69-6; H = 6-9.
C12H14O3 requires C = 69-9; H = 6-8 per cent.

a-Benzoylprupionic acid, C5H5*CO*CHMe*C02H. — Perkin and
Caiman (loc. cit., p. 157) attempted to prepare this acid by using
the conditions which so readily convert ethyl benzoylacetate into
benzoylacetic acid, namely, hydrolysis with concentrated sulphviric
acid at the ordinary temperature, but without success. We have
also made a number of experiments in the same direction, and find
that, under these conditions, the ester either remains unchanged
or is decomposed, with formation of a neutral oil, which is doubtless
propiophenone. Ultimately, we were successful in preparing con-
siderable quantities of the acid in the following way. Ethyl
a-benzoylpropionate (1 mol.) was mixed with a 3 per cent, aqueous
solution of potassium hydroxide (2 mols.), and well shaken from
time to time, and until almost the whole quantity had dissolved.
After about two days, the remaining neutral oil was extracted with
ether, the aqueous solution mixed with ice, and acidified, when
an oily acid separated, which soon crystallised. This was collected,
left in contact with porous porcelain until quite dry, and then
crystallised from a mixture of benzene and light petroleum :

0-1850 gave 0-4565 CO., and 0-0899 HoO. C = 67-3; H = 5-4.
CioHiQOg requires C = 67-4; H = 5-6 per cent.

When titrated with i\'/10-barium hydroxide, 0'3885 neutralised
0-1990 Ba(OH)o, whereas this amount of a monobasic acid,
C10H10O3, should" neutralise 0-1881 Ba(0H)2.

a-Benzoylpropionic acid separates from a mixture of benzene
and light petroleum in colourless, glistening crystals, melts at
82 — 83° with evolution of gas, and gives only a brown coloration
when ferric chloride is added to its alcoholic solution. The ester
from which the acid had been prepared gave a faint violet

VOL. XCV. 6 T

2046 HOPE AND PERKIN : ETHYL BENZOYLACETATK.

coloration with ferric chloride, which was doubtless due to the
presence of traces of ethyl benzoylacetate, and the statement of
Perkin and Caiman (Joe. cit.) that ethyl benzoylmethylacetate
(a-beuzoylpropionate) gives no coloration with ferric chloride is
probably correct. If this be so, there is a striking difference in
this particular between the mono-substitution derivatives of ethyl
benzoylacetate and those of ethyl acetoacetate, since the latter
give intense violet colorations with ferric chloride.

Ethyl a-benzoi/lisobuti/rate, CeHj'CO-CMeg-COgEt. — This di-
substitution derivative may be obtained in a yield of 60 to 70 per
cent, of that theoretically possible by the following method of
preparation.

Ethyl a-benzoylpropionate (15 grams) is added to finely divided
sodium* (rS grams) suspended in tolviene, and, after remaining
for three hours, the toluene solution is decanted from traces of
undissolved sodium, mixed with methyl iodide (11 grams), and
heated to boiling for three hours. The product is mixed with ether,
washed with water and dilute hydrochloric acid, dried, and, after
removing the toluene and ether by evaporation, an oil is obtained
which distils at 153 — 156°/ 19 mm., and gives no coloration when
ferric chloride is added to its alcoholic solution :

0-1441 gave 03748 COg and 0-0967 HgO. C = 70-9 ; H = 7-4.
Ci3Hie03 requires C = 70-9; H = 7-3 per cent.

There can be no doubt that this oil is practically pure ethyl
a-benzoyh'sobutyrate, but subsequent experience (p. 2049) shows
that it would be desirable, on future occasions, to treat this oil
with aqueous potassium hydroxide, in order to remove traces of
etlivl a-benzoylpropionate which it may possibly contain. Many
experiments were made with the object of obtaining a-benzoyl-
isobutjrric acid by the hydrolysis of this ester, but they were all
unsuccessful. When left in contact with concentrated sulphuric
acid for two days, it remained mostly unchanged, but was partly
decomposed, with the formation of neutral oils. The action both
of aqueous and alcoholic potassium hydroxide led to the formation
of much benzoic acid.

Ethyl a-benzoyl-fi-phenylisobutyrate, C6H5*CH2*CMeBz"C02Et. —
This substance is readily obtained when ethyl a-benzoylpropionate
(I2-3 grams) is added to finely-divided sodium' (1'7 grams) suspended
in toluene, &nd, after remaining for three hours, the toluene solution
is decanted, mixed with benzyl chloride (7-6 grams), and heated to
boiling for three hours. The product, isolated in the usual manner,
distilled at 223 — 228°/ 19 mm., and gave no coloration on the
addition of ferric chloride to its alcoholic solution. Analysis

* Prepared by melting sodium under toluene and shaking vigorously.

HOPE AND PERKIN: ETHYL BENZOYLA.CETATE. 2047

showed that this substance was pure ethyl a-benzoi/l-fi-phenyl-
isobutyrate :

0-1228 gave 0-3450 CO2 and 007S1 ILO. C = 76-6; H = 70.
C19H00O3 requires 0 = 770; H = 6-7 per cent.

In the case of this disubstitution derivative, also, many attempts
were made to obtain the free acid by hydrolysis either with alkalis
or acids, but without success.

Etliyl a-Benzoylhuiyralc, CeHs-CO-CHEt-COoEt, Ethyl a-Benzoyl-

a-ethylbutyrate, CgHj'CO'CEts'COoEt, Ethyl a-Benzoyl-a-methyl-

butyrate, CcHs'CO-CMeEt-COoEt, and Ethyl a-Benzoyl-fi-phenyl-

a-ethylpropionate, CeHj-CHa-CEtBz-COoEt.

The ethyl a-benzoylbutyrate employed in the following experi-
ments was prepared exactly as described by Perkin (Trans., 1884,
45, 179; 1885, 47, 241), namely, by adding ethyl benzoylacetate
(5 grams), and then ethyl iodide (10 grams), to a solution of
O'G gram of sodium in 15 c.c. of absolute alcohol. After heating
on the water-bath for about an hour and a^half, the product was
isolated in the usual manner, and purified by fractionation under
diminished pressure.

It distilled at 168 — 171°/ 19 mm., and gave a faint violet
coloration when ferric chloride was added to its alcoholic solution :

0-1307 gave 0-3396 CO2 and 0-0860 HgO. C = 70-8; H=:7-3.
CjgHjgOg requires C = 70-9; 11 = 73 per cent.

Perkin (loc. cit.) gives 210 — 211°/ 90 mm. as the boiling point
of this ester,

a-Benzoylbutyric acid, CeHs-CO-CHEt-COgH. — Although ethyl
benzoylacetate is so readily converted into benzoylacetic acid by
concentrated sulphuric acid in the cold, ethyl a-benzoylbutyrate is
only very slowly attacked under the same conditions, and much
ester remains undecomposed even after solution in a large excess
of sulphuric acid for fourteen days. "When the ester is allowed
to remain for two days with methyl-alcoholic potassium hydroxide
(15 per cent.) at the ordinary temperature, a considerable quantity
of potassium carbonate separates, and a neutral oil is formed,
which distils principally at about 210 — 220°, and evidently consists
mainly of phenyl propyl ketone. The alkaline solution yields, on
acidifying, a copious precipitate of benzoic acid. Similar results
were obtained with dilute methyl-alcoholic potassium hydroxide
(3 per cent.), but ultimately it was found that a-benzoylbutyric
acid may be obtained in a pxire condition by employing aqueous
alkali under the following conditions. Ethyl a-benzoylbutyrate
(1 mol.) is shaken mechanically with 3 per cent, aqueous potassium

6 T 2

204.8 HOPE AND PERKIN : ETHYL BENZOYLACETATE,

hydroxide (2 mols.) for two days, and the neutral oil removed by
extraction with ether. The alkaline solution is mixed with ice,
acidified, extraction with pvxre ether, the ethereal solution dried and
evaporated at as low a temperature as possible, when a colourless
oil is obtained which soon crystallises. After remaining in contact
with jDorous porcelain until quite free from oily impurity, the acid
was cautiously crystallised from a mixture of benzene and light
petroleum :

0-1595 gave 0-4002 COo and 00952 HoO. C = 68-4; H = 6-6.
0-1620 „ 0-4107 CO2 „ 0-0916 HoO. C = 69-l ; H = 6-2.
CijHjgOs requires C = 68-8; H = 6-2 per cent.

On titration with i\'/10-barium hydroxide, 0-5533 neutralised
0-2413 Ba(0H)2, whereas this amount of a monobasic acid,
CuHjoOg, should neutralise 0-2484 gram.

a-Benzoylbutyric acid sejDarates from a mixture of benzene and
light petroleum in colourless, glistening plates, and melts at
85 — 87° with evolution of gas.

It appears to be more unstable than the corresponding methyl
acid (a-benzoylpropionic acid), since on keeping, even in a stoppered
tube, it gradually becomes sticky, whereas the latter remains crisp
under the same conditions.

Ethyl a-henzoyl-a-ethylhutyrate, CeHg-CO'CEto'COoEt. — In the
earlier research (Perkin, Trans., 1884, 45, 182), an attempt was
made to introduce a second ethyl group into ethyl a-benzoyl-
butyrate by treating it with sodium ethoxide and ethyl iodide
in the usual manner, and, although the product was not purified
by distillation,* its examination was thought to indicate that it
consisted in the main of ethyl a-benzoyl-a-ethylbutyrate. We now
find that it is very difficult to introduce a second ethyl group
into ethyl a-benzoylbutyrate, and the yield of ethyl a-benzoyl-
a-ethylbutyrate obtained, even under the best conditions, is only
small.

In the first experiments, ethyl a-benzoylbutyrate was digested,
in alcoholic solution, with the theoretical amount of sodium
ethoxide and excess of ethyl iodide. The product, isolated in the
usual manner, was found to distil almost entirely below 160°/
20 mm., and the distillate evidently consisted mainly of ethyl
derivatives of acetophenone, hydrolysis having taken place under
the conditions employed. Since it was possible that the large
amount of sodium ethoxide present at the beginning might have
produced the hydrolysis, the experiment was repeated, with this

* At the time tliis research was carried out, the method of fractionating under
diminished pressures, now so common, had not been developed.

HOPE AND PERKIN : ETHYL BENZOYLACETATE. 2049

difference, that the alcoholic sodium ethoxide was added drop by
drop to the mixture of ethyl a-beuzoylbutyrate and ethyl iodide,
but, in this case also, the product consisted principally of neutral
oils, together with some ethyl benzoate. Negative results were also
obtained when ethyl a-bonzoylbutyrate was treated, in dry ethereal
solution, with sodium, and then with ethyl iodide. Ultimately it
was found that ethyl a-benzoyl-a-ethylbutyrate may be prepared,
although in small yield, by the following process. Ethyl a-benzoyl-
butyrate (22 grams) is added to finely-divided sodium (23 grams)
suspended in toluene,* and left until almost the whole of the
sodium has dissolved ; the red toluene solution is then decanted
from any unchanged sodium, and heated on the sand-bath with
excess of ethyl iodide. The product, isolated as usual, yielded a
considerable fraction, distilling at 176 — 179°/20 mm., which, on
analysis, gave numbers intermediate between those required for
ethyl a-benzoylbutyrate and ethyl a-benzoyl-a-ethylbutyrate. In
order to remove the former, the mixture was shaken mechanically
with a considerable excess of 3 per cent, aqueous potassium
hydi'oxide for two days, and the unhydrolysed oil extracted with
ether. It now distilled at 179 — 183°/ 20 mm., gave no coloration
with ferric chloride, and evidently consisted of pure ethyl a-benzoyl-
o-ethylbutyrate :

0-1311 gave 0-3488 COo and 0-0921 HgO. C = 72-5 ; H = 7-8.
C15H20O3 requires C = 72-5; H = 8-0 per cent.

The yield obtained was approximately 20 per cent, of that
theoretically possible. In order to determine the reason for the
small yield of ethyl a-benzoyl-a-ethylbutyrate, even under the most
favourable circumstances, an experiment was made with the object
of ascertaining whether this might be due to the sodium derivative
of ethyl a-benzoylbutyrate undergoing decomposition before it
reacted with the ethyl iodide.

The sodium derivative was prepared in toluene solution, and
digested on the sand-bath, care being taken to exclude moisture,
but, even after boiling for five hours, no appreciable decomposition
could be detected, and almost all the ester was recovered unchanged.
That the smallness of the yield of ethyl a-benzoyl-o-ethylbutyrate
obtained in the experiments described above is, in some way, partly
due to the comparatively slow action of the ethyl iodide is clearly
indicated in the following experiments.

I. The sodium derivative of ethyl a-benzoylbutyrate was pre-
pared in toluene solution, digested with excess of methyl iodide in
the usual manner, and the product, after distillation, shaken
mechanically with an excess of 3 per cent, aqueous potassium

* See footnote, p. 2046.

2050 HOPE AND PERKIN : ETHYL BENZOYL ACETATE.

hydroxide for two days. The unhydrolysed ester distilled at
163 — 165°/ 18 mm., gave no coloration with ferric chloride, and
consisted of pure ethyl a-henzoyl-a-methylbutyrate,
CeHj-CO-CMeEt-CO.Et :

01120 gave 0-2932 COo and 0-0787 HgO. C-71-4; H = 7-8.
Cj4Hjg03 requires C = 71'8; PI = 7*7 per cent.

The yield of ester obtained in this experiment was roughly 60
per cent, of that theoretically possible, and, when the alkaline
extract was acidified, there was only a slight turbidity, and no
a-benzoylbutyric acid separated on standing.

II. The sodium derivative of ethyl a-benzoylpropionate was
digested, under the same conditions as in (I), with excess of ethyl
iodide, and the product, after treatment with potassivim hydroxide,
yielded an oil w-hich distilled at 165 — 167°/20 mm., and consisted
of ethyl a-benzoyl-a-methylbutyrate :

0-1528 gave 0-4033 OO2 and 0-1066 HoO. C = 71-9 ; H = 7-7.
Cj4Hjg03 requires C = 7r8; H = 7-7 per cent.

In this experiment, the yield obtained was considerably less than
in (I), and, when the alkaline extract was acidified, a precipitate
of a-benzoylpropionic acid separated after some time, showing that
the decomposition of the sodium derivative of the ethyl a-benzoyl-
propionate by the ethyl iodide had not been complete.

III. In order to obtain further evidence that the rapidity of
action of the halogen derivative employed for substitution has some-
thing to do with the yield of disubstitution product, the action of
benzyl chloride on the sodium derivative of ethyl a-benzoylbutyrate
was investigated. Ethyl a-benzoylbutyrate (15 grams) was con-
verted into the sodium derivative by the action of sodium (1-6
grams) on its toluene solution, as in the previous cases, pure
benzyl chloride (12 grams) was then added, and the whole boiled
for one hour.

The product, isolated in the usual manner, distilled almost

completely at 225 — 229°/ 17 mm., gave no coloration with ferric

chloride, and consisted of pure ethyl a-henzoyl-fi-phenyl-a-ethyl-
propionate, CeHg-CHg-CEtBz-OOaEt :

0-1296 gave 03683 COo and 0-0842 HgO. C = 77-5; H = 7-2.
C20II22O3 requires C = 77-4; H = 7-l per cent.

The jneld of this disubstitution derivative was more than 75 per
cent, of that theoretically possible.

These experiments do not sufficiently account for the smallness
of the yield obtained when the sodium derivative of ethyl a-benzoyl-
butyrate is digested with ethyl iodide, and it is just possible that
this may be due to the decomposition of the ethyl iodide into

STUDIES IN THE CAMPHANE SERIES. PART XXVII. 2051

ethylene and hydrogen iodide during the prolonged boiling in
toluene solution. Experiments will be instituted in order to deter-
mine whether such decomposition actually takes place under these
conditions, because, if this were so, the liberated hydrogen iodide
might well decompose some of the ester, and thus account for the
small yield of the diethyl substitution derivative.

The authors wish to state that much of the expense of this
investigation was met by a grant from the Research Fund of the
Chemical Society.

The Schunck Laboratory,

TlIK UNIVEHSriY,

Manuhesstek.

CCXXIV. — Studies in the Campkane Series. Fart
XXVII. Camphorylplienyltriazen (Camp)}iordiazo-
aminohenzene) and its Bearing on the Coyistitution
of Diazoaniino-compoun ds.

By Martin Onslow Forster and Charles Samuel Garland.

Since the discovery of the first diazoamino-compound by Griess,
the jDroblems connected with the constitution of triazen derivatives
have maintained their interest for chemists to the present day;
whilst, however, the investigation of aromatic diazoamines has
been continuous, the progress of the branch dealing with aliphatic-
aromatic triazens has been intermittent. That such derivatives
are obtainable fromdiazonium salts and aliphatic secondary amines
was shown by Baeyer and Jaeger {Ber., 1875, 8, 148 and 893), and
by Wallach (Annalen, 1886, 235, 233); it was found also that
bisdiazoamino-derivatives arise from aliphatic primary amines
(H. Goldschmidt and Holm, Ber., 1888, 21, 1016; H. Goldschmidt
and Badl, Ber., 1889, 22, 933),

CHg-NH, + 2C6H5-N2C1 = CH3-N(N2-C6H5)2 + 2HC1,
a normal diazoamine being produced only from benzylamine
(Goldschmidt and Holm, loc. cit.). Here the subject remained
apparently untouched until 1903, when Dimroth discovered that
aliphatic-aromatic triazens may be synthesised by an application
of the Grignard reaction to organic azoimides (Ber., 1903, 36,
909), and this observation has been so fruitful in the hands of its
author that a new series of diazoamino-compounds containing

2052 FORSTER AND GARLAND :

alkyl groups has been brought to light, of which the most remark-
able member is diazoaminomethane, or dimethyltriazen, produced
by the action of magnesium methyl iodide on methylazoimide
(Dimroth, Ber., 1906, 39, 3905; compare also Dimroth, Ber.,
1905. 38, 670; Dimroth, Eble, and Gruhl, Ber., 1907, 40, 2390).

The jDrincipal point of interest in connexion with aliphatic-
aromatic triazens, as with those of purely benzenoid origin, lies in
their dynamic isomerism, and it appeared to us probable that an
investigation of the diazoamines theoretically obtainable from
aminocamphor and raethylaminocamphor would help to free this
part of the subject from the obscurity which still prevails. Keeping
in mind the readiness with which diazo-i/z-semicarbazines are pro-
duced from camphoryl-i/'-semicarbazide (Trans., 1906, 89, 222),
we have subjected aminocamphor and its methyl derivative to the
action of diazonium salts, and find that in absence of mineral
acid coupling proceeds smoothly but slowly; by observing certain
precautions specified below, the products may be isolated and
crystallised. According to this method of formation, the simplest
members of the two classes would be represented respectively by
the formulse :

p TT /Ch.nh.n:n.c,h, ch-n(ch3).n:n.c,h,

and as regards the derivatives of methylaminocamphor there is
no doubt that the latter expression is faithful to the facts;
camphorylphenylmethyltriazen and its substitution products are
svifficiently stable towards mineral acids to form definite, crystalline
salts which, when warmed with dilute acids, are resolved into
methylaminocamphor and the corresponding diazonium salt.

Camphorylphenyltriazen, on the other hand, is highly sensitive
towards mineral acids, and even acetic or picric acid is able to
liberate nitrogen from it ; no member of the series which includes
its derivatives, with one exception to be mentioned later, gives
the slightest indication of a diazonium chloride when treated with
hydrochloric acid. Taken alone, therefore, the behaviour of
camphorylphenyltriazen towards acids would suggest the character
of camphordiazoaminobenzene rather than that of benzenediazo-
aminocamphor :

C8H,,<^^ « 5 mste.d of C8H,,<^^ " \

This indication is confirmed by the behaviour of the substance
towards phenylcarbimide, which transforms it into camphordiazo-
diphenylcarbamide, the structure of which is established by its

STUDIES IN THE CAMPHANE SERIES, PART XXVII. 2053

resolution into diphenylcarbamide, nitrogen, and a camphor residue,
without a trace of diazonium salt:

OH /'VH-N:N.NH-CeH,e,H,.N:C:0 r. rr .CH'NIN.N.C.H,
CsH,,<^^ ^^s^u<^0 CO-NH-C«H,

This is the first time that agreement between the course of the
attack by phenylcarbimide and that of the acid resolution has
been observed in connexion with aliphatic-aromatic diazoamino-
compounds. Dimroth, in a communication already quoted {Ber.,
1905, 38, 670), has made it plain that phenylmethjdtriazen, phenyl-
ethyltriazen, and phenylbenzyltriazen are resolved by hydrogen
chloride into aniline, nitrogen, and the corresponding alkyl
chloride, whilst phenylcarbimide converts them into carbamide
derivatives, from which, in each case, benzenediazonium salt is
removed by acids, whence it follows that Dimroth "s triazens would
appear to behave towards acids and phenylcarbimide according to
the formulae :

X-NIN-NH-CeHr, and X-NH-NIN-CcHs
respectively, where X represents the alkyl or substituted alkyl
group.

For a reason which will now appear, we believe that this incon-
sistency in the attitude of Dimroth's triazens towards hydrogen
chloride, on the one hand, and phenylcarbimide, on the other, is
illusory, and is due to the non-appearance of an intermediate
carbamide arising from X-NIN-NH-CrHj. We base this view on
the observation that the camphordiazodiphenylcarbamide
obtained from camphorylphenyltriazen and phenylcarbimide is
transformed quantitatively and with great facility into an isomeric
substance,

PTT ^9h-n:n-n-cvh, . ^j. ch-n-n:n-c,h,

^8^1*^00 C0-NH-C,H5 "^ ^8^i4<.cO CO-NH-C.h;

which, in distinction from its generator, yields benzenediazonium
salt on resolution by acids. Although this rearrangement involves
the migration of the phenylcarbamic radicle, Cj-^Hj'NH'CO, it seems
to us the only possible interpretation of the facts, and if accepted
must lead, in our opinion, to the recognition of Dimroth's triazens
and of camphorylphenyltriazen itself as diazoamino-compounds of
the type X'NIN-NH'QHj, where X represents the alkyl and
camphoryl groups. In other words, the conflicting evidence
brought to light by Dimroth is probably due, not to a tautomeric
change induced by hvdrogen chloride in the direction :

x-NH-N:N-aH. -^ x-n:n-nh-c«h.

2054 FOHSTER AND GARLAND:

followed by resolution of the triazen into alkyl chloride, nitrogen,
and aniline, but rather to a molecular transformation of the diazo-
carbamide :

X-N:N-N-C,H5 _ X-N-NIN-CgH,

CO-NH-CfiHs "^ CO-NH-CeHg'

proceeding so rapidly that only in the case of the heavily-weighted
camphor derivative has it as yet been possible to arrest the change
at it5 initial stage,* Even the diazocarbamide from camphoryl-
phenyltriazen, although stable in the solid state, changes very
rapidly when dissolved, and, being optically active, affords an oppor-
tunity to follow the alteration in the polarimeter.

The foregoing conclusion as to the constitution of the aliphatic-
aromatic triazens being opposed to that of Dimroth and of
H. Goldschniidt (loc. cit., and Ber., 1905, 38, 1096), it is necessary
to refer to those experiments of the former investigator with Eble
and Gruhl {Ber., 1907, 40, 2390) which led him to the opinion
indicated. These consisted in preparing bisdiazoamino-compounds
from the aliphatic-aromatic triazens by the action of diazonium
salts, and in examining the products of resolving them with alcoholic
acid. The quoted authors premise that the bisdiazoamino-
compound from phenylmethyltriazen and benzenediazonium chloride
should be:

C.H -NIN-N-CH, aH.-N-NIN-CH,

DO I 6 _., 0 O I 6

according to the constitution of the original triazen being :

CeHg-NIN-NH-CHs or CgHs-NH-NIN-CHg
respectively, but although they found that the bisdiazoamino-
compound, instead of yielding methylamine and two molecules of
benzenediazonium salt, breaks up into one molecule of elemental
nitrogen and one molecule of diazonium salt, they nevertheless
reject the unsymmetrical formula, and prefer the symmetrical one.
Their reason for doing so is the observation that the product of
coupling toluenediazonium chloride with phenylmethyltriazen is
identical with that obtained from tolylmethyltriazen and benzene-
diazonium chloride, whence they conclude that it has the con-
stitution :

* It is proposed, however, to re-examine the behaviour of some among the better
known diazoamino-corapounds towards phenylcarbimide from the new standpoint in
the hope of establishing other cases in which the initial diazocarbamide may be
isolated. Our experiments suggest that by working in darkness and by selecting
appropriate solvents, isomerism of the type which occurs in the camphor series may
be revealed elsewhere. — M. 0. F.

STUDIES IN THE CAMPHANE SERIES. PART XXVII. 2055

rather than :

aH.-N-NIN-CH, C-H/N-NIN-OH,

0 5, "'or ' ^ I 3,

CyH^-NiN c,H5-n:n

and explain the production of nitrogen (1 mol.) and diazonium
salt (1 mol.) by assuming the regeneration of the triazen.

For the following reasons the evidence from the bisdiazoamino-
compounds is not, in our opinion, of a character to overthrow the
formula, X'NIN'NH'C^IIj, for the aliphatic-aromatic triazens.

1. Dimroth and his colleagues have shown that the bisdiazoamino-
derivative from phenylmethyltriazen and benzenediazonium salt is
identical with the product from methylamine and two molecules of
benzenediazonium salt, and that it is resolved by acids into one
molecule of diazonium salt and one molecule of nitrogen along
with aniline and methyl chloride. At first they were disposed to
interpret this as proving that the bisdiazoamino-compound arises
from methylamine in the following way :

CeHs'NgCl + CHs'NHo = CeHs-NIN-NH-CHg + HCl,
C,H5-N:N-NH-CH3 — > CgHj-NH-NIN-CHg,
CgH.-NoCl + CeH5-NH-N:N-CH3 = C6H5-N(N2-C6H5)-N:N'CH3 + HCl,
and this appears to us a more reasonable explanation than to
assume that the symmetrical bisdiazoamino-compound would yield
only one molecule of diazonium salt.

2. The unsymmetrical structure, C6H5*N(N.2'C7H7)'NIN*CH3, for
the bisdiazoamino-derivativc prepared from

CcH.-N.Cl + C^H-'NsH-CHa,
and from

C^H^-NoCl + CeH^-NgH-CHg,
and rejected by the quoted authors as involving migration of the
R'No-complex, in spite of its apparent sequence from the production
■ of toluenediazonium chloride, aniline, nitrogen, and methyl chloride
by the action of hydrochloric acid, is not so improbable as to be
dismissed in face of this strong evidence supporting it, now that
Dimroth's own most interesting observations in the tribenzoyl-
methane series (Dimroth and Hartmann, Ber., 1908, 41, 4012) have
shown that a benzene-0-azo-compound may change into the isomeric
benzene-C'-azo-derivative on fusion. Moreover, the transformation
of diazoaminobenzene into aminoazobenzene probably depends on
a similar migration, which, if still repugnant, may be evaded or
explained in the following manner :

aH,-N— N=N-CH3 rC"H/N-N-N-CHon

iN-N-CgHs [_ N-N-CgH, J

C-H/N N=N-CH„

' 7,1, 3

X-X-C'H. '

2 056 FORSTER AND GARLAND:

representing the existence of an intermediate condition of the
molecule, not materialised experimentally, where some play of force
occurs between the two pairs of doubly linked nitrogen atoms.

3. It is hardly consistent to base conclusions regarding the con-
stitution of the bisdiazoamino-compounds upon the products of
resolution by acids, when the products of resolving the triazens
themselves, pointing as they emphatically do to the expression
X-NIN-NH-CgHs, are ignored.

A general survey of the evidence, then, appears to us firmly to
establish the formula X'NIN'NH'CqHs for the aliphatic-aromatic
triazens, and it is to be supposed that in the process of formation
by coupling the diazonium salt and the primary amine, sufficient
attraction for the hydrogen atom is exerted by the more negative
phenyl group to effect the transformation :

X-NH-NrN-CgHg — ^ X-NIN-NH-CeH,.

It is noteworthy that more than twenty years ago H. Goldschmidt
and Molinari (Ber., 1888, 21, 2578) laid down this principle for
aromatic diazoamino-compounds containing different radicles, while
rejecting it for benzylphenyltriazen, because of the structure
of the diazocarbamide obtained by the action of phenylcarbimide.
We are inclined to the view that a closer examination of
the aromatic triazens, X'NgH'Y, will show them also to be
embraced by the generalisation in question, as claimed by
Goldschmidt and Molinari, and, although aware that much experi-
mental work has been recorded in opposition, we attach consider-
able importance to the following considerations in support of it.

1. The competition between two aryl groups for the hydrogen
atom of the triazen chain being so much more evenly balanced
than that occurring between an aromatic and an aliphatic residue,
it is reasonable to suppose that environment is the dominant factor
in phenomena which fail to distinguish between X*N!N*NH'Y and

x-nh-n:n-y

2. The numerous cases of resolution by acids upon which current
views regarding the constitution of aromatic diazoamino-compounds
are based would appear, most frequently, to have been studied at
temperatures ranging from that of the laboratory to 100°, instead
of at zero, or below. It is highly significant that phenyl-a-naphthyl-
triazen, whether prepared from o-naphthylazoimide and magnesium
phenyl bromide, or from magnesium a-naphthyl bromide and
phenylazoimide, should yield aniline and a-naphthalenediazonium
chloride without naphthylamine when resolved by alcoholic hydro-
chloric acid in a freezing mixture (Dimroth, Eble, and Gruhl, loc.
cit., 2401).

3. There does not appear to have been recorded a case in which

STUDIES IN THE CAMPHANE SERIES. PART XXVII, 2057

two isomeric diazocarbamides have arisen by direct action of phenyl-
carbimide on a diaryltriazen.

In conclusion, it may perhaps be wortli while to point out that
the isomeric transformation of the diazocarbamide obtained by the
direct action of phenylcarbimide on camphorylphenyltriazen con-
stitutes fresh evidence as to the untrustworthy character of this
agent in problems concerning the elucidation of structure (compare
Michael, Ber., 1905, 38, 22).

Experimental.

Camphorylphenyltriazen {Camphordiazoaminohenzene),
,CH-N:N-NH-a.H.

CsHn<r^''^^^'"^"""

An alkaline solution of aniinocamphor was prepared by dissolving
30 grams of the carbonate in dilute acetic acid, and adding 20 per
cent, sodium carbonate; 10 grams of aniline were diazotised, and
the liquid having been rendered alkaline with sodium carbonate,
the ice-cold solutions were mixed. The api^earance did not change
at first, but a pale brown, flocculent precipitate followed the addition
of 20 per cent, sodium carbonate, 250 c.c. of which were used; the
solid product was augmented by dissolving 100 grams of crystal-
lised sodium acetate in the liquid, which was filtered after half an
hour.

Throughout the coupling process the materials were protected
from light, towards which the triazens are sensitive, and it was
found more conducive to rapid filtration not to use the pump ; the
washed product was roughly dried on porous earthenware and
dissolved in a small quantity of chloroform, from which the
suspended water was removed by sodium sulphate, and on adding
about five times its bulk of petroleum (b. p. 80 — 100°) to the dark
brown, filtered solution, the triazen separated during spontaneous
evaporation. Recrystallisation from a mixture of chloroform and
petroleum gave well-defined, pale brown, centimetre-long prisms,
the substance being obtained almost colourless by dissolution in
boiling petroleum (60 — 80°), which deposits lustrous needles on
cooling :

0-1879 gave 25-6 c.c. No at 18° and 760 mm. N = 15-74.
CjjjH.ijONg requires N = 15-50 per cent.

CamphorylphenyUnazen decomposes at about 150°, the tempera-
ture varying according to the rate at which it is raised. It is
slightly soluble in boiling water, which does not decompose it, but
dissolves freely in cold methyl and ethyl alcohols, ethyl acetate,
acetone, chloroform, ether, or "benzene, m.ore sparingly in hot

2058 FORSTER AND GARLAND:

petroleum; a solution containing 0"3907 gram, made up to 25 c.c.
with chloroform, gave a^ 0°35' in the 2-dcm. tube, whence [a]p 18'6°.

When covered with cold glacial acetic acid, the substance dis-
solved, and slow liberation of gas began soon afterwards; with an
alcoholic solution of picric acid, gas was evolved very slowly, the
pale yellow soliition rapidly becoming orange. On passing dry
hydrogen chloride into an ethereal solution of camphorylphenyl-
triazen, bubbles of gas quickly appeared, along with a white pre-
cipitate, which dissolved on adding water; the aqueous solution
gave a negative result when poured into alkaline i8-naphthol, con-
taining only aniline hydrochloride, which was identified by con-
version into acetanilide. Moreover, when rubbed with ice-cold
hydrochloric acid, the crystals became viscous and intumesced, but
the acid liquor did not develop a coloration with alkaline i8-naphthol,
and the addition of concentrated hydrochloric acid to a freshly
prepared solution in glacial acetic acid was equally fruitless in this
respect, although giving rise to vigorous effervescence. Further
evidence as to the position of the mobile hydrogen atom was
adduced by the indifference of an alcoholic solution towards
M-phenylenediamine hydrochloride, which immediately reddens
diazoaminobenzene, and also by the observation that a solution of
camphorylphenyltriazen in phenol may be heated gradually until
the decomposing point is reached without change of colour ; finally,
a solution of the substance in pyridine containing )8-naphthol was
heated to the boiling point without any indication of benzeneazo-
)3-naphthol being j^roduced.

The silver derivative arose from an attempt to methylate the
triazen by leaving a solution in chloroform with silver oxide and
methyl iodide in the dark room during three days; the filtered
liquid was diluted with petroleum and allowed to evaporate spon-
taneously, when a transparent, pale brown varnish remained. Cold
acetone converted this into a crystalline paste, and, after recrystal-
lisation from boiling acetone, greenish-yellow needles were obtained :

0-1416 gave 0-0540 AgCl. Ag- 28-72.

CigHgoONgAg requires Ag = 28-57 per cent.

The svibstance became dark brown at about 150°, afterwards
blackening, and undergoing complete decomposition at 180°.

We failed to transform the silver derivative into camphoryl-
phenylmethyltriazen by the action of methyl iodide, and a similar
want of success in connexion with phenylmethyltriazen is recorded
by Dimroth (Ber., 1905, 38, 679); action appears to occur, but
not in the direction anticipated.

STUDIES IN THE CAMPHANE SERIES. PART XXVII. 2059

Camphordiazodiphenylcarbamide, ^^^n'Ckr\ (\r\\jTi n, o

CO CO'N H'C^gHjj

Nine grams of freshly prepared, recrystallised camphorylphenyl-
triazen, dissolved in 100 c.c. of benzene (dried with sodium), were
left with 4 grams of phenylcarbimide in a stoppered vessel pro-
tected from light; after forty-eight hours the odour of ?socyanate
was not longer perceptible, and 11 grams of crystals had separated,
the remainder of the product (1 gram) being precipitated by
petroleum. Recrystallisation from hot petroleum (b. p. 60 — 80°)
gave lustrous, colourless needles, melting with complete decom-
position at 147° :

0-1980 gave 25-4 c.c. No at 24° and 758 mm. N = 14-35.
^23-^20^2-^4 requires N = 14-36 per cent.

The substance is freely soluble in cold chloroform, less readily
in methyl and ethyl alcohols, benzene, ethyl acetate, or acetone,
whilst boiling petroleum dissolves it very sparingly, nearly 1000 c.e.
being required by 1 gram. Owing to the readiness with which it
is transformed into the isomeride by acetone, pyridine, and the
alcohols, the safest means of recrystallising it is extraction with
hot petroleum, or precipitation from the benzene solution by cold
petroleum. A solution containing 0-1002 gram, made up to 20 c.c.
with dry pyridine, gave Oj, 1°33' in the 2-dcm. tube when examined
immediately, rising to 2°7' in twenty-four hours ; this corresponds
with [a]j5 154'7° for the substance itself, and indicates almost
complete transformation into the isomeric carbamide within the
period stated, [0]^ 2ir4° instead of 220-6°. The carbamide
becomes deep yellow when covered with cold concentrated hydro-
chloric acid, but gas is not liberated until the temperature is raised,
and the diluted liquid does not develop colour with alkaline
)8-naphthol; furthermore, coupling does not occur in cither acetic
acid or pyridine.

Resolution by Glacial Acetic Acid. — When the substance is
covered with cold glacial acetic acid, there is no . change in
appearance, and ga« is not set free, but, on warming the liquid,
dissolution occurs, brisk effervescence takes place, and crystals of
diphenylcarbamide separate from the liquid ; attempts to identify
the form of the camphor residue have failed, the neutralised
filtrate from diphenylcarbamide yielding on steam distillation a
pale yellow oil having a pleasant odour. On carrying out the
above experiment in a flask communicating with a nitrometer, and
sweeping out air by means of carbon dioxide, the amount of gas
could be measured :

20G0 FORSTER AND GARLAND :

0-2383 gave 156 c.c. No at 23° and 764 mm. N = 7-4.

CogHofiOoN^ requires ^N = 7-2 per cent.
The diphenylcarbamide melted at 235° after recrystallisation,
and gave N = 131 per cent. (CjaH^.^ONo requires N = 13-2 per cent.).

_ .CH-NIN-N-CeHg
Transformation of the Carbamide, C8Hj4<^ i PO'NH-r H '

^ „ .CH-N-NIN-CgH,,
tnto the Isomeride, G^i±^^<^^^ CO-JSTH-C H

Although the carbamide (m. p. 147°) which arises by direct
action of pheuylcarbimide on camphorylphenyltriazen readily loses
nitrogen when warmed with glacial acetic acid, the element is not
liberated when a sohition in pyridine is raised to the boiling point.
The change which takes j^lace is the rearrangement indicated in the
headline, and in order to accomplish this it is not even necessary
to heat the solution, exposure to light during one to two days being
sufficient. On diluting the pyridine largely with water, minute,
felted needles are precipitated, having the same weight as the
original material; recrystallisation from hot absolute alcohol,
followed by glacial acetic acid, raises the melting point to 209°,
when complete decomposition takes place :

0-2134 gave 27-3 c.c. No at 24° and 763 mm. N = 14-40.
C03H26O2N4 requires N = 14-36 per cent.

The substance is freely soluble in cold pyridine, moderately in
cold ether or benzene, and in boiling acetone, chloroform, ethyl
acetate, methyl alcohol, and ethyl alcohol, crystallising in minute,
snow-white needles. A solution containing 0-1020 gram, in 20 c.c.
of dry pyridine, gave Op 2°15' in the 2-dcm. tube, whence
[ajn 220-6°.

Resolution hy Acids. — The transformed diazocarbamide is much
more resistant towards acids than the original material, being able
to withstand the action of boiling acetic acid; moreover, dry
hydrogen chloride has no effect on the substance suspended in
ether at 20°. Hydrolysis was brought about, however, by warm
mixtures of hydrochloric or nitric with glacial acetic acid, and by
50 per cent, sulphuric acid with a few drops of alcohol, benzene-
diazonium salt being produced in each case. Owing to an
unexpected difficulty, the resulting camphorylphenylcarbamide
could not be obtained in crystalline form, the result of neutralising
the acid liquid being, in each case, a viscous oil, which was trans-
formed into a hard resin by continued action of aqvieous potassium
hydroxide. The reason for this was not discovered until an
attempt was made to prepare camphorylphenylcarbamide from

STUDIES IN THE CAMPHANE SERIES. PART XXVII. 2()Gl

aminocamplior and phenylcarbimide (see below), but there was no
difficulty in establishing the production of bcnzencdiazonium salt,
the diluted solution of hydrolysed diazocarbamide, when filtered
from camphorylphcnylcarbamide, giving a bulky precipitate of
benzeneazo-)8-naphthol, which was recrystalliscd and identified.

Action of I'heni/lcai'hiinide on Aminocamphor.

On adding phenylcarbimide to a moderately concentrated
ethereal solution of aminocamphor, the resulting action was suffi-
ciently vigorous to boil the solvent; when the odour of wocyanate
was no longer perceptible, the honey-like mass deposited on
evaporating the ether was dissolved in glacial acetic acid and
precipitated with water in order to remove excess of aminocamphor.
All attempts to crystallise the substance having failed, we suspected
the i^resence of two isomeric carbamides, similar to those produced
by the action of potassium cyanate on aminocamphor hydro-
chloride (Trans., 1905, 87, 110), and the oily mixture in the latter
case having been transformed into the crystalline i/'-carbamide by
the action of hot aqueous potassium hydroxide, the gummy mass
from aminocamphor and phenylcarbimide was digested on the
water-bath during eight hours with 10 per cent, aqueous potassium
hydroxide, treatment which had the desired effect. The hard,
friable cake was finely powdered, washed with water, dried in air,
and covered with a small quantity of cold methyl alcohol, in which
it dissolved freely, but immediately separated in crystals containing
one molecule of the solvent. Finally, the substance was recrystal-
liscd twice from methyl alcohol, and heated in the steam-oven
during twelve hours :

0-2871 gave 25-0 c.c. No at 20° and 763 mm. N = 1000.
C17H22O2N2 requires ^=978 per cent.

Camphorylpheni/l-\p-carba7nide melts at 152°, It is freely soluble
in cold methyl and ethyl alcohols, benzene, chloroform, ethyl
acetate, and acetone, but dissolves very sparingly in boiling
petroleum, which deposits minute, white needles on cooling; the
crystals from methyl alcohol are lustrous, transparent, clear-cut
prisms, which become sticky in the desiccator, and retain the
solvent after seven days :

0-3859 gave 30-7 c.c. No at 20° and 767 mm. N = 9-18.
Ci7H..o02N2,CH40 requires N = 8-80 per cent.

In this form the substance sinters at about 60°, remaining pasty
until 90° is reached, when it becomes opaque, and finally melts
at 152°.

A solution containing 0-2008 gram (m. p. 152°), made up to

VOL. xcv. ■ 6 u

20G2 FOllSTEll AND GARLAND :

110 c.c. with chloroform, gave a^, 0°15' in the 2-dcm. tube, -whence
[ajn 124°, this low figure recalling that of caniphoryl-i/'-carbamide
(loc. cit.). The action of nitrous acid appears to indicate the
jisetido-iorm in preference to the normal, giving rise to an unstable
nitroso-derivative ; this compound will be investigated further, as
the product of reduction should be interesting.

Cainphoryl o-nitrophenyllriazen {Cainphordiazoaiaino-o-nilrohenzene),

Fifteen grams of amiuocamphor carbonate were dissolved in
dilute acetic acid at zero, treated with 7 grams of o-nitroaniline
which had been diazotised in a mixtvire of acetic and hydrochloric
acids, and then with excess of crystallised sodium acetate; no
precipitation took place until sodium carbonate was added, when
the diazoamino-compound separated as a yellow powder. On adding
water to a solution of the substance in acetone, golden-yellow
leaflets crystallised ; the melting point was somewhat indefinite, gas
being evolved at about 120° :

0-1115 gave 17-2 c.c. Ng at 17° and 767-5 mm. N = 17-84.
^16-^20^3-^4 requires N = 17-72 per cent.

The diazoamino-compound is moderately soluble in cold methyl
and ethyl alcohols, dissolving freely in acetone, chloroform, benzene,
or ethyl acetate; it is only slightly soluble in cold petroleum, and
crystallises from the hot solvent in clusters of yellow, lustrous
needles. A solution containing 0-1064 gram, made up to 25 c.c.
with chloroform, gave a^ — 2°4' in the 2-dcm. tube, whence
[a]o- 242-8°.

Glacial acetic acid dissolves the triazen readily without liberating
gas, but on adding one drop of dilute hydrochloric acid to the
solution, brisk effervescence sets in; neither with dilute nor con-
centrated hydrochloric acid was there the slightest indication of
a diazouium salt being produced.

Cam2)horyl-va.-nitrophenyltriazen {Camphor diazoamino-m.-nitrobenzene),
CH-N:N-NH-C,H,-NO,(m)

The coupling was effected as in the previous case, and the product

separated very slowly in the form of a pale yellow precipitate; the

drained substance was dissolved in cold acetone, from which a

felted mass of fawn-coloured needles crystallised on dilution with

'•A-ater. After recrystallisation from a mixture of benzene and

STUDIES IN THE CAMPHANE SERIES. PART XXVII. 2063

petroleum, the melting point was somewhat indefinite, decom-
position occurring in the neij);libourhood of 122°:

0-1175 gave 18-0 c.c. Nj at 17° and 764 mm. N^ 17-87.
C16H20O3N4 requires N = 17*72 per cent.

The substance is freely soluble in methyl and ethyl alcohols,
acetone, chloroform, or ethyl acetate, less readily in benzene ;
petroleum dissolves it on warming, but not freely, the diazoamino-
compound separating in lustrous needles. Cold glacial acetic acid
dissolves it very readily without liberating gas, but a minute
quantity of mineral acid added to this liquid sets up immediate
effervescence. On treating the substance with cold concentrated
hydrochloric acid, gas is rapidly liberated, but neither the liquid
nor the original substance gives the slightest indication of a con-
densation product when mixed with an alkaline solution of
)8-naphthol.

Although the colour of the purified solid is very pale, a solution
containing O'S gram in 100 c.c. of chloroform was too dark to
transmit yellow light in the 2-dcm. tube, and on diluting to
400 c.c, when readings in the polarimeter could be made, no
rotation was discernible.

Caiiiphoryl-]}-nitrophenijltriazen {Camphor cliazoamino-'^-nitrohenzenfi),
^CH-NIN-NH-CeH^-NO. (p)

Fifty c.c. of aminocamphor hydrochloride solution, containing
about 15 grams of the base, were treated with crystallised sodium
acetate in excess, and mixed with an acetic acid solution of diazo-
tised jj-nitroaniline prepared from 6 grams of the base. Precipita-
tion did not take place in the ice-cold liquid until 20 per cent,
sodium carbonate had been added in considerable excess, the pale
yellow solid being filtered and washed after about one hour in the
dark room. The roughly-dried substance was made into a paste
with a small quantity of cold acetone, which developed an intense
magenta-coloured solution, and freed the compound from associated
water; on dissolving the drained material in a further quantity
of acetone and diluting with water until crystals appeared, pale
yellow, felted needles were obtained, melting at 167° with vigorous
intumescence :

0-2058 gave 32-2 c.c. N. at 24° and 771 mm. N- 17-81.
CicHooOgNjf requires N = 17-72 per cent.

The substance is moderately soluble in cold methyl and ethyl
alcohols and in cold acetone, dissolving more freely in ethyl acetate ;
it is insoluble in petroleum, and only moderately soluble in boiling

6 U 2

2064 FOKSTER AND GARLAND

benzene, forming a solution wliicli is almost colourless and deposits
very pale yellow, lustrous prisms on cooling. When covered with
a small pi'oportion of cold pyridine, the substance dissolves, but
the liquid sets immediately to a hard mass, no doubt containing
pyridine of crystallisation. A solution prepared from 0'1089
gram, made up to 25 c.c. with chloroform, gave a^ 1°0' in the
2-dcm. tube, whence [a]^ 114-8°.

The triazen does not effervesce with cold glacial acetic acid, but
it is decomposed immediately by hydrochloric acid; the liquid,
however, does not develop a coloration with alkaline i8-naphthol.
On adding 2 c.c. of concentrated hydrochloric acid to 0'5 gram
of the substance suspended in 4 c.c. of glacial acetic acid, steady
liberation of gas took place, and a brown solution was formed,
yielding an oil on dilution with water; we have failed to identify
this product, which always accompanies nitrogen and the
appropriate aromatic derivative when the unmethylated triazen
derivatives are decomposed by acid, but 2>nitroaniline was isolated
from the acid liquid after removing the camphor residue with
ether.

When rubbed with concentrated aqueous potassium hydroxide,
the substance becomes pale brown, the colour being destroyed on
dilution, but if the triazen is heated with aqueous alkali a faint
odour of camphor becomes perceptible, and an intense violet
coloration is developed on dilution. These changes are probably
due to the formation of an insoluble j^otassium derivative, which
is readily dissociated by w^ater and is decomposed on heating ;
potassium hydroxide develops a deep red coloration in an alcoholic
solution of the triazen, whilst on w-arming the liquid for a few
moments, and then adding water, a very intense but transient
violet colour appears.

Unsuccessful attempts have been made to methylate this com-
pound by the action of methyl sulphate in presence of alkali, and
by heating with methyl iodide and alcoholic jiotassium hydroxide
or silver oxide. Similar resistance was displayed towards benzoyl
chloride.

Camphwyl-i^-methoxyphenyltriazen {Camphor diazoamino-'p-methoxy-
6e«.»e), c,H,<9«-^-«-N'i-°eH.-0-CH3(;,)

Ten grams of aminocamphor carbonate were dissolved in dilute
acetic acid, and treated with an acid solution of 2?-methoxybenzene-
diazonium chloride (from 5 grams of jj-anisidine), to which con-
siderable excess of crystallised sodium acetate had been added;
the liquid remained clear, and even on treatment with suflBcient

STUniFS IN TIIF OAMPHAXK SEHIES. PAHT XXVFI. 2005

sodium carbonate to give strong alkalinity there appeared only a
turbidity. During twenty-four hours in the ice-chest, however,
there separated a pale brown, crystalline precipitate, which was
dissolved in cold acetone and reprecipitated with water; on adding
light petroleum to the solution in cold benzene, lustrous, colourless,
six-sided leaflets crystallised, melting and decomposing at 142°:

0-2895 gave 0-7217 COo and 0-2020 HoO. C = 67-99; H = 7-75.

0-1928 „ 24-2 c.c. No at 22° and 765 mm. N = 14-31.
CJ7IT23O2N3 requires C = 67-77; 11 = 7-64; N = 13-95 per cent.

The triazen dissolves freely in acetone or chloroform, less readily
in methyl and ethyl alcohols and in benzene; it is moderately
soluble in boiling petroleum, from which it crystallises on cooling
in colourless, transparent, six-sided plates, A sokition containing
0-2100 gram, made up to 25 c.c. with chloroform, gave a^ 0°50' in
the 2-dcm. tube, whence [o]u 49-0°.

The behaviour of the substance towards hydrochloric acid is
noteworthy. When this agent is added to a solution in glacial
acetic acid, gas is liberated immediately, and the product does not
give any marked indication of coupling with alkaline jS-naphthol,
but if the solid material is covered with concentrated hydrochloric
acid, there is no perceptible evolution of gas, and after a few
minutes' contact, mixing with alkaline /8-naphthol develops a bright
red coloration ; when heated with the acid, gas is set free, and the
product also develops colour with alkaline iS-naphthol. This
experiment suggests that the triazen undergoes limited transforma-
tion in the direction :

ch.n:n-nh.c,h,.o.ch3

CsHu<

CH-NH-N:N-aH,-0-CH

o'-^i ^ ^^^a

under the influence of mineral acid at the elevated temi^erature
necessary to effect the noi'mal decomposition ; if this explanation
is correct, it is not surprising to find the products of decomposing
both aryldiazo-groups when diaryltriazens are resolved by hot
mineral acids.

Camphoryl-'^-hromophenyltriazen (Camphordiazoamino-p-bromobenzene),

On adding ^^bromobenzenediazonium chloride (from 8 grams of
p-bromoaniline) in dilute acetic acid to aminocamphor carbonate
(15 grams), which had been converted into a dilute solution of the
acetate, the liquid remained clear until free acid was removed by

20()fi FOnSTER AND OARLAXD:

soduim carbonate, whou a faint, turbidity appeared, gradually
increasing during twenty-four hoiirs at zero in the dark room;
even then the separation of the diazoamino-compound was not
complete. The siibstance was prc'cipitatcd from cold acetone by
adding water, and then recrystallised by diluting the solution in
benzene with petroleum, when colourless needles separated, melting
and decomposing at 152° :

0-3002 gave 3r25 c.c. N, at 20° and 760 mm. N = 11-90.
CjcHooONgBr requires N = 12-00 per cent.

The compound is freely soluble in methyl and ethyl alcohols,
acetone, ethyl acetate, or chloroform, less readily in benzene, and
only sparingly in boiling petroleum; a solution containing 0-2290
gram, made up to 25 c.c. with chloroform, gave Cjj 1°9' in the
2-dcm. tube, whence [aj^ 62-7°.

It is not decomposed by concentrated hydrochloric acid until
the liquid is warmed, when gas is liberated, but the test for a
diazonium salt gave a negative result.

Camphor ylphenylmethyliriazen (Benzenediazomethylaminocamphor),

ch.n(CH3)-n:n-c,h,

Nine grams of methylaminocamphor were suspended in water
by adding sodium carbonate to a dilute solution of the hydro-
chloride, and in presence of much ice, treated with a dilute solution
of benzenediazonium chloride prepared from 4 grams of aniline,
to which, after diazotisation, considerable excess of a 20 per cent,
solution of sodium carbonate had been added. On stirring with
crystallised sodium acetate, a pale brown, sticky mass adhered
to the glass, so that the liquid from which it separated could be
poured away; rubbing with cold alcohol caused the product to
become crystalline, and, after drainage, and double repetition of
this treatment, the substance was dissolved in cold acetone, from
which, on adding water, it crystallised in brilliant, pale brown
prisms, melting at 98° without evolving gas :

01573 gave 20-4 c.c. Ng at 17° and 763 mm. ISr = 15-11.
C17H23ON3 requires N = 14*74 per cent.

The triazen is freely soluble in acetone, and dissolves readily in
cold alcohol and in petroleum; a solution containing 0-2161 gram,
made up to 20 c.c. with chloroform, gave a^ 5°5' in the 2-dcm.
tube, whence [ojj, 235*2°. In behaviour towards mineral acid it
distinguishes itself sharply from the class of triazens just described,
being soluble in cold concentrated hydrochloric acid without losing
nitrogen, and, on pouring the liquid into an alkaline solution of
)S-naphthol, the deep red azo-compound is precipitated :

STUDIES IN THE OAMPIIANE SERIES. PART XXVII. 2007

0-1 8.11 gave 0-1 Gl 2 Ccn^-No-CioH^O. CcH5-No = 37-2.

0-2464 „ 0-2148 C^H.-No-CioH^O. CcH5-No = 36-9.

C^Hs'No-CVHjsON requires CJl3-No = 36-8 per cent.

The scission by acid is thus practically quantitative, the azo-
componnd molting at 129° and 133° before and after recrystal-
lisation respectively. The diazonium complex is not eliminated,
however, when a solution of camphorylphenylmethyltriazen in dry
pyridine containing /3-naphthcl is heated to the boiling point.

Camphoryl-o-nitrophenylmethi/Uriazen {o-Nitrohenzenediazovietlt.ylataino-

7 ^ r. TT /CH-N(CH3)-N:N-C "H -NO,, (o)
camphor), C3Hj,<^,^ ^ '' ' ' - ^ ^

The coupling proceeded in the expected fashion, the product
becoming somewhat sticky during filtration, but returning to the
solid state on treatment with a small quantity of cold alcohol;
recrystallisation from warm petroleum (b. p. 60 — 80°) gave lustrous,
yellow needles, melting at 116° without evolving gas:

0-1246 gave 18-8 c.c. No at 18° and 753 mm. N = 17-26.
Cj-HooOsN^ requires N = 16-96 per cent.

The triazen crystallises readily from methyl and ethyl alcohols,
being only moderately soluble in the cold media; acetone, benzene,
ethyl acetate, and chloroform dissolve it freely, but it is only
slightly soluble in cold petroleum. A solution containing 0-2353
gram, made up to 25 c.c. with chloroform, gave a^ 5°40' in the
2-dcm. tube, whence [a]p 301 0°.

On adding concentrated hydrochloric acid to the pale yellow
solution in glacial acetic acid, the colour is immediately destroyed,
owing to the formation of the colourless hydrochloride, the st&bility
of which is indicated by the fact that on mixing the liquid with
alkaline )8-naphthol the colour is very faint; when the dry sub-
stance is covered with concentrated hydrochloric acid, it forms a
colourless sohition, which does not effervesce, but deposits the
hydrochloride in crystals, and only after gently warming the liquid
is the intense red azo-compound developed with alkaline )8-naphthol.

Camphoryl-va-nitrophenylmethyltriazen {m-Nitrohenzenediazoviethyl~
aminocamphor), C^lI^^<!l^ \ j/ b 4 - ^ \

The initial prodvict of coupling 7/i-nitrobenzenediazonium chloride
and methylaminocamphor was almost colourless, but became red
and sticky during filtration, and after dissolution in cold alcohol
crystallised only very slowly; it was necessary to recrystallise the
substance several times from alcohol and petroleum, employed

•JOfiS FORSTER AND GARLAND:

alternately, before the melting point was constant, when lustrous,
silky, yellow needles were deposited from the latter solvent, melting
at 8f — 82° without evolving gas :

0-1292 gave 19-3 c.c. No at 16° and 751 mm. N = 17-19.
C,7Hoo03N4 requires N = 16'96 per cent.

The substance is freely soluble in cold acetone, ethyl acetate,
chloroform, or benzene, dissolving readily in hot alcohol and in
petroleum ; although pale yellow in the solid state, the hydrocarbon
solutions are colourless. A solution containing 0'1239 gram, made
up to 25 c.c. with chloroform, gave a^ 1°48' in the 2-dcm. tube,
whence [a]p 181-6°.

When rubbed with concentrated hydrochloric acid, the compound
is transformed into a colourless, gelatinovis hydrochloride, which
dissolves on being gently warmed ; the liquid then develops a deep
orange precipitate -with alkaline /3-naphthol.

Camjihoryl-'^-nitropheiiylmethyUriazen {^-XitrohenzenecUazomethylamino-
camphor, Kj^W.^^<^^^

This compound separated as a yellow, flocculent precipitate on
adding sodium carbonate to the mixture of methylaminocamphor
and diazonium salt in dilute acetic acid; after crystallisation from
dilute acetone, which deposited the svibstance in pale yellow, silky
needles, it melted at 150° without evolving gas:

0-1761 gave 25-7 c.c. No at 20° and 767 mm. N = 16-85.
CJ7H22O3N4 requires N = 16-96 per cent.

The triazen is freely soluble in cold acetone, chloroform, benzene,
or ethyl acetate, less readily in methyl and ethyl alcohols and in
hot petroleum, the solution in the last-named being colourless. A
solution containing 0-2359 gram, made up to 20 c.c. with chloro-
form, gave Ojj 7°20' in the 2-dcm. tube, whence [ajj, 310-8°.

The yellow solution in glacial acetic acid becomes colourless on
adding concentrated hydrochloric acid, but there is no liberation
of gas, and, after warming gently, the liquid develops an intense
red colour with alkaline )8-naphthol :

0-1952 gave 0-1804 NOo-CoH^-No-CjoH^O. NOo-C6H4-No = 47-3.

0-1971 „ 0-1796 NOo-CoH^-No-CjoH^O. N02-CoH4-N2 = 46-6.

NOo-CcH4-N2-C„HigON requires NOo-CcH4-N2 = 45-4 per cent.

The azo-compound decomposed at 247° and 249° before and after
recrystallisation respectively.

Two grams of the ja-nitro-compound were dissolved in a mixture
of glacial acetic and concentrated hydrochloric acids, and heated
on the steam-bath until nitrogen ceased to appear; on diluting
with water, there separated a crystalline precipitate of 2>chloro-

STUDIES IN TTTE OAMPTIANE SERIES. PART XXVIl. 20G9

nitrobenzene, more of which was obtained by extracting the filtrate
with ether. After distillation in steam, the substance melted at
82 — 83°, whilst the residue in the flask contained a very small
quantity of y)-nitrophenol ; methylaminocaniphor was recovered
from the acid liqiiid, and identified as the picrate, m. p. 188°.

The pronounced tendency towards salt-formation, which charac-
terises the series of triazen derivatives from methylaminocamphor,
and which helps to distinguish them from the class referred to
aminocamphor itself, has been studied in the case of the p-nitro-
compound by adding to an ethereal solution of the triazen sufficient
acid dissolved in ether to precipitate the colourless salt, which was
then filtered, washed with dry ether, and preserved in the desiccator,
where no change in appearance has been observed during the lapse
of six months.

The hydrochloride melts and decomposes at 146°:

0-2462 gave 0-0959 AgCl. Cl-9-61.

Ci7Hoo03N4,HCl requires CI = 9-66 per cent.

The sulfhate melts and decomposes at 151°:

0-4185 gave 0-1298 BaSO^. S = 4-25.

(C^;IIoo03N4)o,HoSO^ requires S = 4-22 per cent.

The nitrate melts and decomposes at 124°:

0-0978 gave 15-2 c.c. N., at 18° and 760 mm. N- 17-95.
Ci7Ho203N4,HN63 requires N = 17-81 per cent.

On decomposing these salts with dilute ammonia, unaltered
camphoryl-^J-nitrophenylmethyltriazen was recovered.

Camphoryl-p-rnethoxi/pheni/lmethyltriazen (p-Melhoxi/betizenediazometliyl-

, X ^ XT ^ch-n(ch,)-n:n-gvh,-o-ch„ (»)

C/O

The diazoaniino-compoiind separated on adding sodium carbonate
to the mixture of diazonium salt and methylaminocamphor, and
was crystallised twice from warm dilute alcohol, which deposited
flat, lustrous, colourless needles, melting at 74° without evolving
gas:

0-1654 gave 19-2 c.c. No at 18° and 763 mm. N = 13-46.
CjsHojOoNg requires N = 13-33 per cent.

The substance is freely soluble in all the ordinary organic media,
including petroleum; a solution containing 0-1862 gram, made up
to 25 c.c. with chloroform, gave a^ 3°28' in the 2-dcm. tvibe,
whence [a]^ 232-7°.

When covered with cold concentrated hydrochloric acid, the
compound is immediately dissolved without losing nitrogen, and,
on gently warming the liquid and pouring it into alkaline
j8-naphthol, the intense red azo-compound is produced.

2070 FORSTEK AND r.'ARLAND

Camphwyl-^-hromojyhenylmelhyltriazen (p- Bromohenzenediazomethyl-

_ ^CH-N(CH3)-N:N-C^H,Br (p)
aminocamphor), CgHj^*^ '^

Precipitation of tlie diazoamino-com pound from p-l^romobenzene-
diazoninm chloride and metliylaminocamplior in presence of sodium
carbonate appeared to be complete after two hours in the dark
room; the granular material became somewhat sticky during
washing, but was restored to condition by rubbing with cold
alcohol. After recrystallisation from this medium, the substance
was dissolved in petroleum, which deposited tough, pale pink
needles, melting at 112°, along with clear-cut, transparent, colour-
less prisms, melting at 121°, a mixture of the two modifications
melting at 90°. The two forms were sorted by hand, and recrystal-
lised sej^arately without alteration in the temperature of fusion ;
they gave approximately the same results on analysis :

0-4830 (needles) gave 0-2540 AgBr. Br = 22-37.

0-G843 (prisms) gave 0-3556 AgBr. Br = 22-11.

Cj7Ho20N^Br requires Br = 21-98 per cent.

Both substances dissolve readily in ordinary solvents, and the
difference between them was first attributed to dimorphism until it
was found that their effects on polarised light are almost antipodal ;
a solution containing 0-2246 gram (needles, m. p. 112°), made up
to 25 c.c. with chloroform, gave Oj, 3°55' in the 2-dcm. tube, whence
[o]j, 218-0°, whilst 0-2253 gram (prisms, m. p. 121°), under similar
conditions, gave o^ — 4°17', corresponding to [ojj, — 232-1°. In spite
of this remarkable difference, the two substances behave alike
towards hydrochloric acid, undergoing the resolution characterising
this class of triazens, and consequently developing an intense red
colour when the diluted liquid is poured into alkaline iS-naphthol.

It is noteworthy tha.t the investigation of bromodiazoamino-
benzene in the hands of Hantzsch and F. M. Perkin (Ber., 1897,
30, 1394) brought to light a pair of modifications behaving alike
in every chemical respect, but differing from one another in melting
point ; a similar phenomenon was noticed in connexion with the
/j-chloro-derivative, but not among the nitro-compounds. The
explanation to which Hantzsch and Perkin were impelled repre-
sented the normal and abnormal (lower melting) forms by the
expressions :

CcH.-NIN-NH-CeH^X and CeH^-NH-NIN-CeH^X,
and although phenylcarbimide furnished in each case the same
diazocarbamide,

C,H, N.N ^^cO-NH'CeH,'

STTTDTES TX TITK DAMPIIAVE SERIES. PART XXVTT. 2071

it wns supposed that ihr n.jront, provimislv in coTnliination, trans-
formed the labile, more fusible modification into the " normal "
isoracride (/oc. cif., 1406). It will be noticed, however, that in the
case of camphoryl-2j-bromophenylmethyltriazen, this explanation
would not apply, there being no available hydrogen in the triazen
chain ; moreover, both forms give diazonium salt on treatment with
acid, behaviour which eliminates the possibility of the methyl group
having wandered. We hope to return to this subject later, because
there are two remaining contingencies to be considered. It might
be that in these halogen derivatives of the triazen nucleus, cases
have been brought to light in which isomerism of the type
encountered among the oximcs has been realised, represented by
the formulas :

X-NH-N , X-NH-N

and . . .

Y-N N-Y

The alternative exjjlanation would apply to the camphoryl-
triazens, but not to the benzenoid ones, and depends on the fact
that aminocamphor and methylaminocamphor, arising by reduction
of j'.sonitrosocamphor and its i\^-methyl ether respectively, should
occur in two forms, a's and trans, corresj)onding with bornylamine
and neobornylamine from camphoroxime. Only one form has yet
been noticed, and there seems to be no particular reason why,
among the numerous changes to which these bases and their
derivatives have been submitted, coupling with pbromobenzene-
diazonium chloride should exert such marked selective action.

As in the case of the p-nitro-compound, salts were prepared from
the modification of camphoryl-^^-bromophenylmethyltriazen which
melts at 112°.

The hydrochloride melts and decomposes at 130°:

0-2859 gave 0-0995 AgCl. CI = 8-59.

Ci7HooON'3Br,HCl requires Cl = 8-84 per cent.

The sulphate melts and decomposes at 153° :

0-5878 gave 0-1638 BaS04. S = 3-83.

(Ci7ll220N3Br)2,H2S04 requires S = 3-87 per cent.

The nitrate melts and decomposes at 137°:

0-1448 gave 16-8 c.c. No at 17° and 763 mm. N = 13-52.
Ci7H220N3Br,HN03 requires N = 13*11 per cent.

On decomposing these salts with aqueous sodium carbonate, the
original triazen (m. p. 112°) was recovered.

Royal College of Sciekce, Loxdon.
South Kensington, S.W.

•2072 FdRSTER AND MULLER : TTIE TRTAZO-OROUP. PART X.

CCXX^^ — The Triazo-fjroup. Fart X. Triazoantijyyrii e.

By Martin Onslow Forsteu and Robert Muller.

Recognising that 4-triazo-l-phenyl-2 : 3-dimethylpyrazolone (tri-
azoantipyrine),

^"^s^<CO C-N, '

would present a type of triazoketonc distinct from those wliich have
been already investigated (Trans., 1905, 87, 826; 1908, 93, 72 and
669), we prepared the substance by the action of hydrazoic acid on
antipyryldiazonium sulphate. The structural features which give
it interest are, in the first place, absence of hydrogen from the
neighbourhood of the triazo-group, with the consequent uncertainty
as to the behaviour of this complex under the influence of carbonyl
in the ortho-position, and, secondly, the unsaturated linking by
which the triazotised carbon atom is associated with the next
member of the ring.

The former of these peculiarities no doubt underlies the
indifference of triazoantipyrine towards alkali, which does not
liberate two-thirds of the azidic nitrogen, and thus distinguishes
the substance from those ketonic azoimides which possess the group
Ng'CH'CO in common. The most conspicuous property of triazo-
antipyrine, however, is the spontaneous loss of nitrogen which
occurs in the crystalline material with lapse of time, an alteration
which takes place very rapidly in the dissolved state, the straw-
coloured liquid quickly becoming deep red. It has not been
possible to characterise the resulting azoantipyrine very sharply,
but as the change in question is an unusual point in the chemistry
of the triazo-group, we think it deserves to be recorded. The
choice between the formulas :

t^eHs-N/ ■' j>N and

C,H5-N<

,N(CH3)-C-CH3 C(CH3)-N(CH3).

V-CoH,

^co c-N :n-c CO/

for azoantipyrine cannot be made decisively, because all attempts
to crystallise the substance have failed, and therefore we do not
feel justified in attaching importance to the determinations of
molecular weight. Although the second expression would be in
conventional accordance with the structure of benzenoid azo-
compounds, the production of l-hydroxy-5-phenyltetrazole from

FORSTER AND MULLER : THE TRIAZO-GHOUP. PART X. 207;^

the hypothetical bcnzhydroximic azide (this vol., 184; compare also
Wicland, Ber., 1909, 42, 4199):

so far resembles the learrangement involved in the change:

as to bring the simpler constitution within the range of probability.
On the other hand, it is reasonable to suppose that the bicyclic
structure just rejaresented, in which an osotriazole ring is associated
with a pyrazolone, would not be so unstable as to suffer immediate
loss of nitrogen, and this circumstance, in conjunction with the
colour of the substance and its amorphism, incline us to prefer
the constitutional formula which is analogous to that of azobenzene.
Somewhat indirectly, pcrhap.s, the present subject bears on the
mechanism of diazotisation, inasmuch as it adds one more to the
small, but significant, group of facts which go to show that the
change in question is not confined to benzenoid substances. The
observation that aminoantipyrine may be diazotiscd under con-
ditions similar to those attending the production of benzene-
diazonium salts was made several years ago (Knorr and Stolz,
Annalcn, 1896, 293, 68), but does not appear to have received
the attention it deserves in connexion with the constitution of
diazonium salts. Among other non-benzenoid cyclic systems known
to furnish diazonium salts may be mentioned the triazole and
tetronic acid rings, Thiele and Manchot {Annalen, 1898, 303, 33)
having shown that aminotriazole and aminomethyltriazole :

NH-N NH-N

NH,-C<^,__njj and NH,-C<^__n .^^^^

behave like aniline towards nitrous acid, whilst Wolff and
Lvittringhaus {Annalen, 1900, 312, 133) transformed aminotetronic
acid into a diazo-oxide :

which develojos a colouring matter with alkaline a-naphthol.
Moreover, other diazoanhydrides, described by Wolff and his
collaborators {Annalen, 1902, 325, 129), have been represented as
arising from aliphatic amines, but although the author quoted
regards these compounds as analogous to the diazo-oxide from
tetronic acid, the latter of the two f ormube :

.,. ^O-C-CHg , ^^ OC-CH,

2074 FORSTER AND MULLER : THE TRIAZO-GROUP. PART X.

must, in the opiuiou of mauy chemists, be regarded as agreeing
more completely with the properties of the substances, and has the
advantage of bringing them into line with ethyl diazoacetate.

Excluding these somewhat doubtful substances, therefore, three
■well-established cases remain in which a non-benzenoid cyclic system
has been transformed into a diazonivim salt, and an attempt must
be made to bring the fact into harmony with the more familiar
occurrences of diazotisation, particularly since Cain's theory (Trans.,
1907, 91, 1049) has lifted into greater prominence the seeming
dependence of the diazonium structure on a benzenoid host. From
this standpoint it is noteworthy that in the amino-compounds
derived from the pyrazolone, triazole, and tetronic acid rings, the
immediate environment of the diazotisable nitrogen is to this
extent similar, that the carbon atom which carries the amino-group
is doubly linked with a neighbouring member of the ring system :

NH2-C=C NH2-C=N

(Pyrazolone aud tetronic acid.) (Triazole.)

The underlying principle of Cain's theory is recognition of the
possibility that diazonium salt formation involves participation of
the carbon atom in the para-position with respect to the amino-
group, and the consequent production of a hemi-quinone. The
exclusion of this possibility in the case of the fi.ve-membered ring-
systems under discussion leads apparently to one of two alternatives,
either the abandonment of Cain's theory, or the adoption of the
extension thereto proposed by Morgan and Micklethwait (Trans.,
190S, 93, 617). Of these conclusions, we prefer the latter. There
is so much to be said in favour of regarding diazotisation as
depending on the residual aflanity of the complex to which the
amino-group it attached that a return to Blomstrand's formula
seems retrograde. The adroit inclusion of the ortho-position by
Morgan and Micklethwait would render diazotisable those amino-
derivatives of rings in which a double linking associates the ortho-
member. In the benzenoid series, the participation of the ortho-
position is doubtless one phase only; in the diazonium salts of
pyrazolone, tetrazole, and tetronic acid derivatives, it is probably
static, the formulae:

/N(CH3)-C(CH3) , /NH-C=NC1

C^H.-N/ 1 ! > N/ I I , and

^00 C=NC1=:N ^CH-N— N

.CH2-C(0H)

0< I 1

\C0— C=NC1==N

representing the diazonium chlorides, respectively.

FORSTER AND MULLEU : THE TRIAZO-GROUP. PART X. 2075

EXPEIUMENTAL.

4:-Triazo-l-pheni/l-2 : ^-dimethylpyrazolone [Triazoantipyrine),

Aminoantipyrine sulphate was prcpai'ed by hydi'olysing the
bcnzylidcne compound (8'8 grams), suspended in ether, with aqueous
sulphuric acid (6 grams diluted to 50 c.c.), and freed from benz-
aldehyde by two subsequent extractions ; ether having been removed
from the acid liquid, this was transferred to the dark room,
diazotised, and treated with excess of sodium azide (2'5 grams
instead of 1'95). Vigorous effervescence ensued, and in presence of
a large proportion of crushed ice the triazo-compound separated
in pale yellow leaflets, insufficient cooling leading to an oil which
rapidly solidified. The roughly-dried substance was dissolved
without delay in cold benzene, with which it appears to combine,
the solution being diluted with petroleum, when lustrous, flat,
straw-coloured crystals were deposited, sometimes attaining an inch
in length ; on transferring the substance to porous earthenware,
it rapidly lost its lustre, and melted at 74° to a deep red, effervescent
liquid :

0-0985 gave 0-2079 COo and 00448 H.O. C = 57-56; H = 5-05.
0-0915 „ 24-6 c.c. No'at 20° and 768 mm. N = 31-09.
C11H11ON5 requires 0 = 5764; H = 4-80; N = 30-56 per cent.

Triazoantipyrine dissolves readily in methyl and ethyl alcohols,
benzene, and acetone, but is insoluble in cold petroleum. Inter-
action with sulphuric acid is very violent, being almost explosive
when the concentrated agent is used; yellow fumes are liberated,
and a black tar produced. Even 50 per cent, acid brings about
vigorous decomposition, but by reducing the strength to 25 per
cent., it is possible to measure the gas set free, two-thirds the
azidic nitrogen being evolved :

0-1293 gave 13-2 c.c. No at 17° and 776 mm. N = 12-10.
CijHiiONs requires fN = 12-22 per cent.

The triazo-compound loses nitrogen also when treated with
stannous chloride in hydrochloric acid, but in this case variable
results are obtained, and it is not possible to follow the reaction
quantitatively. Ammoniacal silver oxide is reduced very readily
by the substance, a mirror being deposited on raising the tem-
perature. On adding aqueous potassium hydroxide to an alcohoHc
solution of triazoantipyrine, the behaviour of the substance is found
to be quite different from that of triazoketones in which hydrogen

207() FOKSTEU AM) MULLEU : THE TRIAZO-GROUP. PART X.

is attached to the carbon atom carrying the azoimide complex,
and the usual stormy liberation of nitrogen does not occur.

Azoantipyrine,

X:o C— N: N— C CO'

If the crystallised triazoantipyrine is allowed to remain suspended
in the mother liquor, a remarkable alteration sets in, even when
light is excluded. The crystals lose their brilliancy, changing to
a red powder, whilst the liquid, originally clear and pale yellow,
becomes red and turbid, evolving gas.

This decomposition was accelerated and completed by maintain-
ing the liquid at 40 — 50° during eight to ten hours, when the
red powder was filtered, dissolved in benzene, precipitated by
petroleum, redissolved in chloroform, and reprecipitated by ethyl
acetate. The dull red powder became dark red and slimy when
spread on earthenware, but if left on the filter-paper and allowed
to dry by exposure to air, the paler colour and powdery condition
persisted, and the substance intumesced a few degrees above 165°,
at which temperature it suddenly became dark red :

0-1019 gave 18-2 c.c. No at 17° and 770 mm. N = 2rOO.
C22H22Q2Ne requires N = 20'90 per cent.

The behaviour of t/he substance towards concentrated sulphuric
acid, stannous chloride, and ammoniacal silver oxide was negative.
Picric acid, when added to an alcoholic solution, gave a dark red
precipitate, but this immediately became sticky, and could not be
crystallised. The azo-compound is readily soluble in chloroform,
pyridine, and the alcohols, being sparingly dissolved by ethyl acetate
and by hot petroleum; the behaviovir towards benzene is curious,
for when the substance is covered with a small proportion of the
cold hydrocarbon a deep red solution is formed, but becomes turbid
on further addition of the solvent. It has not been possible to
crystallise the compound, but a specimen obtained by allowing
crystallised triazoantipyrine to undergo spontaneous decomposition
in a stoppered vessel was found to have retained the crystalline
form of the original material, although quite red and containing
only 21 per cent, of nitrogen. On account of the difiiculties
indicated, we do not place much reliance on the determinations of
molecular weight; these varied considerably between 300 and 400,
the latter figure being required Ijy the molecular formula for
azoantipyrine.

Royal College of Science, London.
SoT'TH Kensington, S.W,

I

f

f^ ^{^z^iSiu.^

TILDEN: MENDELEEFF MEMORIAL LECTURE. 2077

MENDELBEFF MEMORIAL LECTURE.

Delivkukd on OcroBEU 21sT, 1909.

By W. A. TiLDEN, D.Sc, LL.D., F.R.S., Past-President of the
Chemical Society.

To many of the present generation of English cliemists, the com-
manding, patriarchal figure of Mendeleeff was quite familiar.
Though his several visits to London were often connected with
official business of the Russian Government Department of Weights
and Measures, of which he was the chief official during the later
years of his life, he came several times with more purely scientific
objects. In 1889 the occasion of his presence in London was the
Faraday Lecture which he had been invited to give to the Chemical
Society, but which, owing to a sudden and urgent recall to his
home, he was unable to deliver in person. His last appearance in
this country was in November, 1905, when the Copley Medal was
awarded to him by the Royal Society.

The Chemical Society can see his face no more, and all that
it can now do is to inscribe high on its roll of honour the name
which, more than any other, will be for ever associated with the
development of the great generalisation known as the periodic
system of the elements.

Dmitri Ivanovitsch Mendeleeff * was the fourteenth and youngest
child of his parents, Ivan Pavlovitsch and Maria Dmitrievna, nee
Kornileff. His father, a former student of the Chief Pedagogic
Institute of St. Petersburg, obtained the appointment of Director
of the Gymnasium at Tobolsk, in Siberia, where he met Maria
Dmitrievna, who became his wife. After a few years at Tobolsk,
he was transferred to school directorships in Russia, first at
Tambov, and afterwards at Saratov. But in order to satisfy the
ardent wish of his wife, he took advantage of an opportunity of
exchange, by which he became once more Director of the College
at Tobolsk, and the family returned to Siberia. Here on January
27th, 1834 (O.S.) was born Dmitri Ivanovitsch, the youngest son.

* For many of the details of Meudeliiefrs career and of his home life the writer
is iudebted to the family chronicle compiled, soon after his death, by his niece,
N. J. Gubkina [ncc Kapustina), and published in St. Petersburg, aKo to pamphlets
by A. Archaugelsky and P. J. Robinowitscli. He also desires to express liis thanks
to Mr. D. V. Jequier, of St. Petersburg, as well as to several Russian friends, for
valuable assistance in translation.

VOL. XCV. 6 X

2078 TILDEN": MENDELt^:EFF MEMORIAL LECTURE.

Soon after his birtli the father became gradually blind from
cataract iu both ej^es, and was obliged to resign, the whole family,
including eight children, having to subsist on a small pension of
1000 roubles (about '£100 per annum). The mother, Maria
Dmitrievna, belonged to the old Russian family, Kornileff, settled
at Tobolsk. They were the first to establish in Siberia the manu-
facture of paper and glass. In 1787 the grandfather of Dmitri
opened at Tobolsk the first printing press, and from 1789 produced
the first newspaper in Siberia, the Irtysch. The glass works were
situated in the village of Aremziansk, a short distance from
Tobolsk.

According to the family tradition, one of the Kornileffs in a
previous generation had married a Khirgis Tartar beauty, whom
he loved so passionately that when she died he also died of grief.
The pure Russian blood thus received a strain of the Mongolian
race, and some of their descendants preserved traces of the
Oriental type. This, however, was not very noticeable in the
features of the chemist.

From her childhood, Maria Dmitrievna was distinguished by
her intelligent wish for instruction, and having no other resource
when her brother Basile went to school she repeated by herself
all his lessons, and thus, unaided, obtained some part of the
knowledge so eagerly desired. There can be no doubt she was a
woman possessed of remarkable vigour of mind, who exercised great
influence over her children. Her activity and capacity are further
illustrated by the fact that when her husband became blind she
revived the business of the glass works, and carried it on till after
his death from consumption in 1847.

Tobolsk was at that time a j^lace of banishment for many
political exiles, the so-called Decembrists, one of whom, Bassargin,
married Olga, an elder sister of Dmitri. To these Decembrists the
boy owed his first interest in natural science. His mother had
always cherished the hope that at least one of her children would
devote himself to science, and accordingl}^ after her husband "s
death and the destruction of the glass works by fire, and sjoite of
failing health and scanty means, she undertook the long and
tedious journey from Tobolsk to Moscow, accompanied by her
remaining children, Elizabeth and Dmitri Ivanovitsch, with the
object of entering the latter, then nearly fifteen years of age, at
the University. Disappointed in this object, owing to official
difficulties, she removed in the spring of 1850 to St. Petersburg,
where ultimately, with the assistance of the Director, PletnofF, of
the Central Pedagogic Institute, a friend of her late husband,
she succeeded in securing for her son admission to the Physico-

TILDEN: MENDELKEFF MEMORIAL LECTURE. 2079

Matliematical Faculty of the Institute, together witli nnuh-needed
pecuniary assistance from the Government.

The debt which Dmitri Ivanovitsch owed to hia, mother he
acknowledged later in the introduction to his work on " Solutions,"
which he dedicated to her memory in the following interesting
lines :

■' This investigation is dedicated to the memory of a mother
by her youngest offspring. Conducting a factory, she could
educate him only by her own work. She instructed by example,
corrected with love, and in order to devote him to science she
left Siberia with him, spending thus her last resources and
strength. iWhen dying, she said, ' Refrain from illusions, insist
on work, and not on words. Patiently search divine and scientific
truth.' She understood how often dialectical methods deceive,
how much there is still to be learned, and how, with tlie aid of
science without violence, with love but firmness, all superstition,
itntruth, and error are removed, bringing in their stead the safety
of discovered truth, freedom for further development, general
welfare, and inward happiness. Dmitri Mendeleeff regards as sacred
a mother's dying words. October, 1887."

In the Pedagogic Institute Dmitri Ivanovitsch was thus able to
devote himself to the mathematical and physical sciences under
the guidance of Professors Leng and Kuj^fer in physics, Woskresen-
sky in chemistry, and Ostragradsky in mathematics. Unfortunately,
at the end of his course, his health failed, and about this time
his mother died. Having been ordered to the South, he fortunately
obtained an ajopointment as chief science master at Simferopol, in
the Crimea. The southern climate soon alleviated the serious
symptoms of lung disorder, and removal being necessary in con-
sequence of the Crimean War, he was able soon afterwards to
undertake a post as teacher of mathematics and physics at the
Gymnasium at Odessa. In 1856 he returned to St. Petersburg,
and at the early age of twenty-two he was appointed privat docent
in the University, having secured his certificate as master in
chemistry.

At this time he ajipears to have passed rapidly from one subject
to another, but he soon found matter for serious and protracted
study in the physical properties of liquids, especially in their
expansion by heat. And when, in 1859, by permission of the
Minister of Public Instruction Mendeleeff proceeded to study under
Regnarilt in Paris and afterwards in Heidelberg, he devoted him-
self to this work, communicating his results to Liebig's Annalen
and the French Academy of Sciences. Returning two years later
to St. Petersburg, he secured his Doctorate, and was soon after-

0x2

2080 TILDEN : MENDEL^EFF MEMORIAL LECTURE.

wards appointed Professor of Chemistry in the Technological
Institute. In 1866 he became Professor of General Chemistry in
the University, Butlerow at the same time occupying the Chair
of Organic Chemistry.

As a teacher, Mendeleeff seems to have possessed a special talent
for rousing a desire for knowledge, and his lecture room was often
filled with students from all faculties of the University. Many
of his former students remember gratefully the influence he
exercised over them.* One of these writes: "I was a stvident in
the Technological Institute from 1867 to 1869. Mendeleeff was
our professor, and in 1868 taught organic chemistry. The previous
course by the professor of inorganic chemistry consisted of a
collection of recipes, very hard to remember, but, thanks to
Mendeleeff, I began to perceive that chemistry was really a science.
The most remarkable thing at his lectures was that the mind of
his audience worked with his, foreseeing the conclusions he might
arrive at, and feeling happy when he did reach these conclusions.
More than once he said, ' I do not wish to cram you with facts,
but I want you to be able to read chemical treatises and other
literature, to be able to analyse them, and, in fact, to understand
chemistry. And you should remember that hypotheses are not
theories. By a theory I mean a conclusion drawn from the
accumulated facts we now possess which enables us to foresee new
facts which we do not yet know.' He was considered among the
students a most liberal man, and they thought of him as a comrade.
More than once during a disturbance between the students and
the administration Mendeleeff supported the students, and under
his influence many matters were put right." (L. G.) Another
former student in the University writes as follows : " I am sorry
to say I did not know Mendeleeff personally. I only had the good
fortune to follow, in the years 1867-69, his lectures on both
Organic and Inorganic Chemistry. The former was an abridged
course, which he had the admirable idea to deliver for us students
of the mathematical branch of the physico-mathematical faculty.
He reduced this course of one lecture a week during one year to
a general review of organic compounds and the general laws of
their structure. You can imagine what it must have been in
the hands of Mendeleeff, thirty-three or thirty-four years old at
that time, in the full enjoyment of his mental powers, and jvist
then plunged into the study of his great generalisations. For me
it was a revelation, being occupied with the great questions con-
nected with the development of the new system of atomic weights,

* For the follf^wing reminiscences, the writer is iudebted to Mr. L. Goldcubcrg
and Prinee P. Kropotkin ict^peciively.

TILDEN: MENDEL^EFF MEMORIAL LECTURE. 2081

the mechanical theory of heat, etc. Grove's, Thomson's, Joule's,
Seguin's works were then just out, and in these years a sudden
blossoming of the natural sciences in all directions seemed to bring
us near to the solution of the great problems of the nature of
matter and of gravitation. Then I followed Mcndclecff's lectures
on Inorganic Chemistry. Tlic ' Principles of Chemistry ' was not
yet out, but he Avas evidently writing it at that time. You know
how much is said in the footnotes to his ' Principles ' ; well, imagine
each of these notes developed into a beautiful improvisation, with
all the freshness of thought of a man who, while he speaks,
evolves all the arguments for and against, there on the spot. The
hall was always crowded with something like two hundred students,
many of whom, I am afraid, could not follow MendcleefT, l)ut for
the few of us who could it was a stimixlant to the intellect and a
lesson in scientific thinking which mvist have left deep traces in
their development, as it did in mine." (P. K.)

One of MendeleefT's most remarkable personal features was his
flowing abundance of hair. The story goes that, before he "was
presented to the late Emperor, Alexander III., his Majesty was
curious to know whether the professor Avould have his hair cut.
This, however, was not done, and he appeared at Court without
passing under the hands of the barber. His habit was to cut
his hair once a year in spring, before the warm weather set in.
His eyes, though rather deep set, were bright blue, and to the
end of his life retained their penetrating glance. Tall in stature,
though with slightly stooping shoulders, his hands noticeable for
their fine form and expressive gestures, the whole figure proclaimed
the grand Russian of the province of Tver.

At home, Mendelceff always wore an easy garment of his own
design, something like a Norfolk jacket without a belt, of dark
grey cloth. He rarely wore uniform or evening coat, and attached
no importance to ribbons and decorations, of which he had many.

As to his views on social and political questions, many people
thought him a rigid monarchist, but he said of himself that he
was an evolutionist of peaceable type, desiring a new religion, of
which the characteristic should be subordination of the individual
to the general good. He always viewed with much sympathy what
is called the feminine question. At the Office of Weights and
Measures, he employed several ladies, and about 1870 he gave
lectures on chemistry to classes of ladies. Nevertheless he con-
sidered women inferior to men both in business and in intellectual
pursuits, and he thought the chief promoters cf the feminine
movement aimed, not so much at equality of political position, as
at opportunities for work and to escape inactivity. But he thought

20S2 TIl.DEN: AlENDELl^EFF MEMORIAL LECTURE.

the feminine temperament specially suited to all branches of art
in the broadest sense of the word, including education.

Mcndeleeff held decided views on the subject of education, which
he set forth in several publications, especially " Remarks on Public
Instruction in Russia" (1901). Here he says, "The fundamental
direction of Russian education should be living and real, not based
on dead languages, grammatical rules, and dialectical discussions,
which, without experimental control, bring self-deceit, illusion,
presumption, and selfishness." Believing in the soothing effect of
a vital realism in schools, he considered that tmiversal peace and
the brotherhood of nations could only be brought about by the
operation of this principle. Speaking of the reforms desirable,
he says that "for such reforms are required many strong realists;
classicists are only fit to be landowners, cajDitalists, civil servants,
men of letters critics, describing and discussing, but helping only
indirectly the cause of pojDular needs. We could live at the present
day without a Plato, but a double number of Newtons is required
to discover the secrets of nature, and to bi'ing life into harmony
with the laws of nature." Mendeleeff was evidently a philosopher
of the same type as our own Francis Bacon.

" I am not afraid," he says later, " of the admission of foreign,
even of socialistic, ideas into Russia, because I have faith in the
Russian people, who have already got rid of the Tartar domination
and the feudal system."

Mendeleeff always dined at six o'clock, and liked to entertain
his friends and relations, but in his own diet he was extremely
moderate. After dinner he enjoyed reading light literature,
especially books of adventure, such as those of Fenimore Cooper or
Jules Verne. But his literary tastes were joeculiar. Though
interested in serious literature and ajipreciating Shakesjoeare,
Schiller, Goethe, Victor Hugo, and Byron as well as the Russian
classics, beginning with Zhoucovsky and Pouschkin, his favourites
among Russian poets were Maicoff and Tuttcheff, and among the
rest Byron. Of the last-named he preferred to all his other works
the gloomy poem called " Darkness," and amc«ig the rest the
"Silentium" of Tuttcheff.

He rarely went to the theatre, and did not approve of frequent
visits to the theatre by his children, as he considered such distrac-
tions tend to destroy concentration and fill the mind with " trifles
and foolishness." On the other hand, he was very fond of pictures,
and he visited all the exhibitions. That he was interested in
questions relating to art, and had given much thought to aesthetic
problems, is indicated by a letter * which he addressed in Novem-
be*", 1880, to the well-known Russian daily paper of that time,
* Considerably condensed in the following abstract.

I

TILDENT: MENDELHEFF MEMORIAL LECTURE. 20<S3

Goloss (The Voice), on the subject of a picture by Koiiindji,
" Night in the Ukraine." Writing of the inflxience of landscape
on different minds, he says, " At first it seemed to me a matter of
personal taste, of individual sensitiveness of different persons to
the beauty of nature." But, rejecting this simple view, he was
led to a conception which he regarded as really satisfactory, and
which he wished to share with others. lie says, " Landscape was
depicted in antiquity, but was not in favour in those times. Even
the great masters of the sixteenth century made use of it merely
as a frame to their pictures. It was the human form which prin-
cipally inspired artists of that epoch; even the gods and the
Almighty Himself appeared to their minds in human shape. In
this alone they found the infinite, the inspiring, the divine. And
this was because they worshipped human mind and human spirit.
This found expression in science in an exceptional development of
mathematics, logic, metaphysics, and politics. Later, however,
men lost faith in the absolute and original power of human reason,
and they discovered that the study of external nature assists even
in the correct appreciation of the nature of the human inner self.
Thus nature became an object of study; a natural science arose
unknown either to antiquity or to the period of the Renaissance.
Observation and experience, inductive reasoning, submission to
the inevitable, soon gave rise to a new and more powerful, more
productive method of seeking truth. It thus became evident that
human nature, including its consciousness and reason, is merely a
part of the whole, which is easier to comprehend as such from
the study of external nature than of the inner man. External
nature thus ceased to be merely subservient to man, and became
his equal, his friend. Dead and senseless as it had been, it now
became alive. Everywhere it presented motion, stores of energy,
natural reason, simplicity, and plan. Inductive and experimental
science became a crown of knowledge, royal metaphysics and
mathematics had now to be content with modest questioning of
nature. Landscape painting was born simultaneously with this
change, or perhaps a little earlier. Thus it will probably come to
pass that our age will hereafter be known as the epoch of natural
science in philosophy, and of landscape in art. Both derive their
materials from sources external to man. . . . Man has, however, not
been lost sight of as an object of study and of artistic creation, but
he now appears, not as a potentate or as a microcosm, but merely as
part of a complex whole."

In 1863, when twenty-nine years of age, Mendeleef? married his
first wife, nee Lestshoff, by whom he had one son, Vladimir,* and
a daughter, Olga; but the marriage proved unhappy, and after
* Died in 1899, aged U.

20S4 TILDEX: MEXDELl^EFF MEMORIAL LECTURE.

living apart for some time there was a divorce. In 1877 he fell
in love with a young lady artist, Anna Ivanovna Popova, of
Cossack origin, and in 1881 they were married. This lady exercised
considerable influence over his views about art, and the walls of
his studv were furnished with many products of her pencil, notably
portraits of Lavoisier, Descartes, Newton, Galileo, Copernicus,
Graham, Mitscherlich, Rose, Chevreul, Faraday, Berthelot, and
Dumas, and others of relatives. After his second marriage,
Mendeleeff lived first at the University, and afterwards in the
apartznents built for the Director at the Bureau of "Weights and
Measures, and here his younger children were born, Lioubov
(Aimee), Ivan (Jean), and the twins, Maria and Vassili (Basile).

In 1890, in consequence of a difference with the administration,
Mendeleeff retired from the Professorship in the University.
During the disturbances among the students in that year, he
succeeded in pacifying them by promising to present their petition
to the Minister of Education. Instead of thanks for this service,
however, the Professor received a sharp reprimand from the
authorities for not minding his own business. The consequence
was that Mendeleeff resigned. Indejoendently of the petition,
however, there were probably deeper reasons for his being out of
favour with the Ministry, connected with his irreconcilable enmity
to the classical system of education already referred to (p. 2082).
Of this he had made no secret, and it had already brought him
into conflict with the authorities. In 1893, however, he was
appointed by M. Witte to the office of Director of the Bureau of
Weights and Measures, which he retained till his death.

In the earlier part of his life, Mendeleeff was interested in
carrying on a series of agricultural experiments on his Tver estate,
Boblovo. The peasants, much struck by his success and the
abundance of his crops, inquired of him whether this was due to
his luck or to his " talent." With a smile and the patois which
he always affected in speaking to the country people, he informed
them that he certainly had " talent," and, as he said afterwards
at home, there is no merit in having luck.

Once during the solar eclipse in 1887 he ascended alone in a
balloon wih the object of making scientific observations. His
assistant, Kovanko, who sat with him in the basket, alighted at
the last moment, probably ordered to do so by his chief because
the balloon would not rise. When the balloon shot up quickly
and disappeared in the clouds, his family was naturally very much
alarmed. Fortunately the hero of the adventure was able to
descend safely, and a few hours later returned to his family from
Moscow. The peasant women thereafter used to tell that Dmitri

TILDEN : MENDELEEFF ME:\I()1{IAL LECTURE. 2085

Ivanovitscli flew on a bubble and pierced the sky, and for this the
authorities made him, a chemist !

Mendeleeff was very democratic in his habits, and when travelling
from the Capital to his estate, six or seven hours by rail, he always
made use of the third class, and on the way talked freely to his
fellow-passengers on all sorts of subjects, so that at the end of
the journey he was surrounded by all sorts of people. At the
railway station, about twelve miles from Boblovo, he was always
met by the same driver, Zassorin, who with his troika of greys
transported the whole family at full gallop, according to Russian
custom.

Such, then, are the chief features of a great jDersonality. If it
be admitted that stories are told of his occasional irritability of
temper, we can well place on the other side of the account the
cordial relations always subsisting between the Professor and his
assistants, the confidence and respect between the Master and his
servants, the deep affection between the Father and his children,
which are known to have persisted throughout his life, and which
could be illustrated by many anecdotes. These stories merely serve
" to give the world assurance of a man."

For us who live on the other side of Europe, separated as we
are by race, by language, by national and social customs, and by
form of government, it is not easy to understand completely the
texture of such a mind, the quality of such genius, and the
conditions, social or political, which may have served to encourage
or to repress its activity. The Russian language may be eloquent,
expressive, versatile, and harmonious, or it may possess any other
good quality that may be claimed for it by those to whom it is
a mother tongue, but the fact remains that it is a barrier to free
intercourse between the Russian people and the -world outside the
Russian Empire. This alone creates a condition which must
influence the development of thought, and must give to Russian
science and philosophy a colour of its own. Mendeleeff was, like
many educated Russians, a man of very liberal views on such
subjects as education, the position of women, on art and science,
and probably on national government. We can hardly guess what
would be the influence on such a nature of a rigid administrative
regime which forbids even the discussion of such questions. We
in England are almost unable to imagine such a state of things
as would be represented by the closing of, say, University College
for a year or more, because the question whether the House of
Lords ought to be abolished had been debated in the Students'
Union. Imagine the Professor of Chemistry, along with his
colleagues, for such a reason deprived of the use of his laboratory

2086 TILDEN: MENDEL^EFF MEMORIAL LECTURE.

bv the police, and only allowed to resume his studies when someone
down at Scotland Yard thought proper. Such being the experience
of most of the Russian Universities and Technical High Schools,
it is not surprising that the output of Russian science, notwith-
standing the acknowledged genius of the Russian people, appears
sometimes comparatively small. The amount of work done by
Mendelceff, both experimental and theoretical, was prodigious, and
all the more remarkable considering the cloudy atmosphere under
which so much of it was accomplished.*

In 1882 the Royal Society conferred on Mendcleeff, jointly with
Lothar Meyer, the Davy Medal. In 1883 the Chemical Society
elected him an Honorary Member, and in 1889 it conferred upon
him the highest distinction in its power to award, namely, the
Faraday Lectureship, with which is associated the Faraday Medal.
In 1890 he was elected a Foreign Member of the Royal Society,
and in 1905 he received the Copley Medal. So far as England is
concerned, his services to science received full acknowledgment. It
is all the more remarkable, therefore, that ' he never became a
member of the Imperial Academy of Sciences of St. Petersburg.

Towards the end of 1906 Mendeleeff's health began to fail.
Nevertheless he was able to attend the Minister on the occasion
of an oflticial visit in January to the office of Weights and
Measures, but he caught cold and, enfeebled as he had been by
influenza in the preceding autumn, inflammation of the lungs set
in. Retaining consciousness almost to the last, he requested even
on the day of his death to be read to from the " Journey to the
North Pole," by his favourite author, Jules Verne. He died in
the early morning of the 20th January (O.S.), 1907, within a few
days of his seventy-third birthday. He was buried in the Wolkowo
Cemetery beside the graves of his mother and son.

Turning now to a survey of Mendeleeff's work as a man of
science, it will be sufficient if we pass lightly over his first essays.
Like so many other chemists, he began by handling simple questions
of fact, his first paper, dated 1854, when he was twenty years of
age, being on the comjDosition of certain specimens of orthite. It
was not till 1859 that he settled down to serious examination of
the physical properties of liquids, which led him to a long series
of experiments on the thermal dilatation of liquids, of which the

* Professor Walden, at the end of a biographical notice recently published in the
Berichie d. Deut. Chcrn. Ges., April, 1909, gives a list of 262 printed publications by
ilendelc'eff. These include, not only memoirs on physical and chemical subjects,
but books, pamphlets, reports, and newspaper articles relating to exhibitions, to
the industries of Russia, to weights and measures, to education, to art, and even to
spiritualism.

TILDEN: MENJ)KLKEFF AlEMOUIAL LECTURE. 2087

chief ultimate outcome was the establishment of a simple expres-
sion for the expansion of liquids between 0° and the boiling point
(Trans., 1883, 45, 126). This formula is liable to the same kind
of modification which has been found necessary in the case of gases.
It is, of course, applicable only to an ideal liquid from which all
known liquids differ by reason of differences of chemical constitu-
tion and consequent differences of density, viscosity, and other
properties. Thorpe and Riicker, by applying van der Waals'
theory of the general relation between the pressure, volume, and
temperature of bodies to Mendeleeff's expression for the thermal
expansion, developed a simple method of calculating the critical
temperature of liquids from observations of their expansion (Trans.,
1884, 45, 135).

Mendeleeff devoted a large amount of time and of experimental
skill to the estimation of the densities of various solutions,
especially mixtures of alcohol and water and of sulphuric acid and
water, and of aqueous solutions of a large number of salts. In
1889 he embodied the whole in the monograph already referred to.
In a paper communicated to the Transactions in 1887 (51, 779),
he stated his views in the following words : " Solutions may be
regarded as strictly definite atomic chemical combinations at tem-
peratures higher than their dissociation temperatures. Definite
chemical substances may be either formed or decomposed at tem-
peratures which are higher than those at which dissociation
commences ; the same phenomenon occurs in solutions ; at ordinary
temperatures they can be either formed or decomposed." This
view was retained by Mendeleeff, and appears in a footnote (p. 64)
in the 7th Russian Edition (3rd English Edition) of the Principles,
1902, where the following passage occurs: "The conception of
solutions as dissociated definite liquid chemical compounds is based
on the following considerations : (1) That there exist certain
undoubtedly definite crystallised chemical compounds (such as
HoS04,H20, or NaCl,2HoO, or CaClo,6HoO, etc.), which melt on a
certain rise of temperature and then form true solutions; (2) that
metallic alloys in a molten condition are real solutions, but on
cooling they often give entirely distinct and definite crystallised
compounds; (3) that between the solvent and the substance dis-
solved there are formed in a number of cases many undoubtedly
definite compounds, such as compounds with water of crystallisa-
tion; (4) that the physical properties of solutions, and especially
their specific gravities (a property which can be very accurately
determined), vary with a change in composition, and in such a
manner as would be required by the formation of one or more
definite but dissociating compounds. . . . The increase in specific

2088 Tii.nEX: mendeleeff memorial lecture.

gravity (il<) varies iti all well-known solutions with tlie proportion
of substance dissolved (^/^j), and this dependence can be expressed
bv a formula (/.s7<^i^ = A + Bp between the limits of definite com-
pounds, whose existence in solutions must be admitted." Applying
this method, he concludes that mixtures of alcohol and water may
contain several definite compounds, such as CoIigO + SHoO. These
views, however, did not prevent his recognising van't Hoff's gas
theory as applicable to dilute solutions.

In conjunction with some of his students, Mendeleeff also studied
minutely the question of the elasticity of gases, and published
several papers on the subject (see Royal Soc. Catalogue), extending
over a period of some ten years from 1872. From the earlier
researches of Regnault and others, it was known that the law of
Bo5de and Marriotte is not strictly applicable either to all gases
or at all jDressures. Mendeleeff and his assistants devoted special
attention to the departures from the theoretical requirements of
the law exhibited by gases under very greatly reduced pressures.
He found that for hydrogen the value of jw diminishes with the
pressure down to 20 mm., while for air, carbon dioxide, and some
others, jiv increases slightly to a maximum.

Another subject to which Mendeleeff' gave a good deal of attention
was the nature and origin of petroleum. Having already reported
in 1866 on the naphtha springs in the Caucasus, in the summer of
1876 he crossed the Atlantic and surveyed the oil fields of Penn-
sylvania. In the course of these investigations, he was led to
form a new theory of the mode of production of these natural
deposits. The assumption that the oil is a product of the decom-
position of organic remains he rejects on a variety of grounds,
which are set forth in a communication to the Russian Chemical
Society (Abstract, see Ber., 1877, 10, 229). Mendeleeff assumes,
as others have done, that the interior of the earth consists largely
of carbides of metals, especially iron, and that hydrocarbons result
from the penetration of water into contact with these compoixnds,
metallic oxide being formed simultaneously. The hydrocarbons
are supposed to be driven in vapour from the lower strata, where
temperature is high, to more superficial strata, where they condense
and are retained under pressure. In 1886, in consequence of
rumours as to the possible exhaustion of the Russian oil fields, he
was sent by the Government to Baku to collect information, and
in 1889 he made a communication on this subject to Dr. Ludwig
Mond, which is printed in the Journal of the Society of Chemical
Industry (1889, 8, 753.)

The influence of the great generalisation known as the periodic
law can best be estimated by reviewing the state of knowledge

TILDEN: MENDELHEFF MEMORIAL LECTURE. 2089

and opinion before tlie announcement and acceptance of the prin-
ciple by the chemical world, and subsequently glancing at the
influence which, directly or indirectly, it has produced on scientific
thought, not only in regard to the great problems to which it
immediately relates, bub to the whole range of chemical theory.

The use of the expression, " atomic weight," implies the adoption
of some form of atomic theory. But forty or more years ago
Dalton's atomic theory was by many of the most philosophical
chemists and physicists regarded as only a convenient hypothesis,
which might bo temporarily useful, but could not be accepted as
representing physical reality. Since that time, however, a variety
of circumstances have contributed to consolidate the Daltonian
doctrine. The estimation of the ratios called atomic weights has
been the subject of research, attended by more and more elaborate
precautions to secure accuracy, from the time of Dalton himself
onward through successive generations down to the present day.
Though the atomic weights of the majority of the common elements
are now known to a high degree of accuracy, the acknowledged
errors have been sufficiently great to render abortive various
attempts to reduce them to any common scheme of mathematical
relationship. As is well known, the most important step toward
the systematisation of atomic weights was taken about 1860,
mainly on the grounds eloquently and convincingly set forth by
Cannizzaro,''' in consequence of which the arbitrary selection of
numbers for atomic weights was superseded by the practical
recognition of the law of Avogadro and the application of the law
of Dulong and Petit, so that a common standard was established.
No general scheme of atomic weights was previously possible,
partial and imperfect efforts in this direction being represented b^
Dcebereiner's triads and the principle of homology made use of by
Dumas. Only so soon as numbers representing the atomic weights
of calcium, barium, lead, and other metals were corrected and
brought into the same category as those of oxygen, sulphur, and
carbon was there some chance of determining whether these
numbers possessed a comm.on factor or were capable of exhibiting
mathematical interrelations which might be regarded as symbolic
of physical relations or even directly dependent upon them. The
first step in this direction was taken by J. A. R. Newlands, who,
after some preliminary attempts in 1864-1865, discovered that when
the elements are placed in the order of the numerical value of
their atomic weights, corrected as advised by Cannizzaro, the
eighth element starting from any point on the list exhibits a
revival of the characteristics of the first. This undoubtedly repre-
* 1858, and later, Faraday Lecture, 1872.

2090 TILDEN: MENDELI?:EFF memorial LECTttRE.

sents the first recognition of the principle of periodicity in the
scries of atomic weights, but whether discouraged by the cool
reception of his '' law of octaves " by the chemical world or from
imperfect apprehension of the importance of this discovery,
Newlands failed to follow up the inquiry. It was not long,
however, before the matter was taken up by others, and doubtless
the improvements in the estimation of atomic weights, following
on the work of Stas, then only recently published, inspired greater
confidence in the approximate accuracy of the numbers adopted
as atomic weights, and thus encouraged inquiry into their relations.
The subject is, indeed, an attractive one, for it involves con-
siderations which lie at the foundations of all our notions respecting
the ph3^sical constitution of matter, and accordingly we find papers
by many chemists dealing with the question of these numerical
relations. Odling especially seems to have given much thought
to the subject, and, ignoring Newlands' previous attempts, he drew
up towards the end of 1864 "■ a table containing a list of all the
then well-known elements, arranged horizontally in the order of
their generally accepted groups, and perpendicularly in the order
of their sevei'al atomic weights. He concludes an article in Watts's
Dictionary a few months later with these words : " Doubtless some
of the arithmetical relations exemplified in the foregoing table
are merely accidental, but, taken altogether, they are too numerous
and decided not to depend on some hitherto unrecognised law."
It is imjaortant to note the words I have italicised.

Such, then, was the state of knowledge about this time. Evidently
the way was being prepared, but the prophet had not made his
appearance, the seer who could look with the eyes of confidence
beyond the clouds of imcertainty which obscured all ordinary
vision.

In March, 1869, Mendeleeff communicated to the Russian
Chemical Society an enunciation of the principle of periodicity
and a statement of some of the consequences of this recognition
of the relation of jDroperties to atomic weight throughout the whole
range of the known elements, and this statement was accompanied
by a table which, while it bears a close resemblance to Odling's
table of 1864, was apparently connected in his mind with an idea
which became clearer and more decisive in the modifications which
he immediately afterwards introduced into the arrangement, f

* Quart. J. Sci., 1S64, 1, 643 ; and Watts' Diet., Vol. Ill, 975.
t .Subjoiued is a translation, as literal as possible., of the German Abstract {Zcitsch.
/. Clwiii., 6, 405). Several obvious misprints have been corrected.

TILDEN: MENDEIJ:EFF MEMORIAL LECTURE. 2091

On the E elation of the Frojjerties to the Atomic Weights of the

Elements.

By D. Mendeleeff.

When tlie elements are aiTanged in vertical columns, according
to increasing atomic weight, so that the horizontal lines contain
analogous elements, again according to increasing atomic weight,
the following arrangement results, from which several general
conclusions may be derived :

Ti = 50 Zr = 90 ? =180

V = 51 Nb= 94 Ta =182
Cr= 52 Mo=: 96 W =186
Mn= 55 Rh = 104-4 Ft =197-4
re= 56 Ru =104-4 Iv =198
Ni = Co= 59 Pd =106-6 Os =199
H =1 Cu= 63-4 Ag=108 Kg =200

Re =9-4 Mg = 24 Zn=65-2 Cd =112

R =11 Al =27-4 ? = 68 U =116 Au =197?

C =12 Si =28 ? = 70 Sn =118

N =14 P =31 As= 75 Sb =122 Ri =210?

0 =16 S =32 Se = 79-4 Te=128?

F =19 CI =35-5 Rr= 80 I =127

Li =7 ISra = 23 K =39 Eb= 85-4 Cs =133 Tl =204

Ca =40 Sr=87-6 Ra =137 Pb =207

? =45 Ce= 92

?Ei- =56 La= 94

nt =60 Di= 95

?Iu =75-6 Tli = 118

1. The elements arranged according to the magnitude of atomic
weight show a periodic * change of properties.

2. Chemically analogous elements have atomic weights either in
agreement (Pt, Ir, Os), or increasing by equal amounts (K, Rb, Cs).

3. The arrangement, according to atomic weights, corresponds
with the valtncy of the elements, and to a certain extent the
difference in chemical behaviour, for example, Li, Be, B, C, N, O, F.

4. The elements most widely distributed in nature have small
atomic weights, and all such elements are distinguished by their
characteristic behaviour. They are thus tyjncal elements, and the
lightest element, hydrogen, is therefore rightly chosen as the typical
unit of mass.

5. The magnitude of the atomic weight determines the pro-
perties of the element, whence in the study of compounds regard
is to be jDaid not only to the number and properties of the
elements and their mutual action, but to the atomic weights of the
elements. Hence the comjDounds of S and Te, CI and I, show,
beside many analogies, yet striking differences.

* Here an error in tlie German translation does an injustice to the original
inasmuch as the Russian word for periodical is rendered " stufcnweise " (gradual).

2002 TiLOEN: mendeli^:eff memorial lecture,

6. It allows the discovery of many neuy elements to be foreseen,
for example, analogues of Si and Al with atomic weights between
^b and 75.

7. Some atomic weights will presumably experience a correction ;
for example, Te cannot have the atomic weight 128, but 123 to 126.

8. From the foregoing table, new analogies between elements
become apparent. Thus U appears as an analogue of B and Al,
which, as is well known, has long ago been established experi-
mentally.

Previous students of the subject had been, for the most part,
struck with the relations obviously subsisting between the members
of the several natural families of elements, but had, with few
exceptions, failed to perceive that there must be a general law
binding the whole together. However, MendeleefF, with that noble
sentiment of justice which always animates the trvily scientific
mind, admits that the idea of a general law had already been
foreshadowed by others, and he says (Faraday Lecture, 1889),
" I now see clearly that Strecker, de Chancourtois, and Newlands
stood foremost in the way towards the discovery of the periodic
law, and that they merely wanted the boldness necessary to place
the whole question at such a height that its reflection on the facts
could be clearly seen."

It may be remarked that Strecker did little more than call
attention to the sequence in the values of the atomic weights of
certain elements, and states that "we must leave to the future
the discovery of the latv of the relations which appear in these
figures " (Theorien u. Experiraente zur Bestimmung der Atom
Gewichte der Elemente, 1859). De Chancourtois, in his work
entitled " Le Vis Tellurique " (1863), devised a geometric method
of representing the atomic weights by coiling rovmd a cylinder a
helix with an angle of 45°, the cylinder being divided vertically
into sixteen equal parts by lines drawn from the circular base.
The points of intersection of the helix with these lines were
supposed to represent the atomic weights of elements which differed
from one another by 16 or by multiples of 16.

Mendeleeff's table of 1869 was subsequently in 1871 modified
so as to assume the form with which we have all been so long
familiar, and which is to be found in every modern text-book.
Thus it may be claimed for Mendeleeff that he was actually the
first, not only to formulate a general law connecting atomic weights
with properties, but was the first to indicate its character, and,
as himself (rrincijdes, 1905, II, p. 28) has pointed out, he was
the first "to foretell the j^^'oycrties of undiscovered elements, or

TILDEN : MENDELKEFF MEMORIAL LECTURE. 201)3

ter the accepted atomic weights " in confidence of its validity.

time was, in fact, ripe for the enunciation of this general
nple, and, the suggestion once given, the relations embodied
le law could not fail to attract other chemists. Accordingly,
)ecember, 1869, Lothar Meyer, with such knowledge of
deleeff's scheme as could be derived from the imperfect German
on of his paper of the previous March, proved himself a
inced exponent of the idea by contributing to Liebig's
alen a paper containing a table, substantially identical with

of Mendeleeff, and his famous diagram of atomic volumes,
h, more clearly even than the tabular scheme, illustrates the
ciple of periodicity.

16 history of science shows many instances of the same kind.
it generalisations have often resulted from the gradual
mulation of facts which, after remaining for a time isolated
;onfused, have been found to admit of co-ordination into a
Drehensive scheme, and, this once clearly formulated, many
cers are found ready to assist in its development. The case
early parallel to the recognition of the operation of natural
;tion by Darwin and Wallace, or it might be compared to the
Dvery of oxygen by Priestley and Scheele and the utilisation
his knowledge by Lavoisier. In each case much preparatory
c had been done, and a body of knowledge had been gradually
mulated which, when duly marshalled and surveyed by the
of a master, could scarcely fail to reveal to him the underlying
ciple. The full consequences, however, would appear only to
w.

be law of periodicity was expressed by Mendeleeff in the
iwing words : *

The properties of the elements, as well as the forms and pro-
ies of their compounds, are in periodic dependence on, or
■ressing ourselves algebraically) form a periodic function of,
atomic weights of the elements." After a brief historical
unt of the discovery of the law by himself, Mendeleeff
dudes by saying (^Principles, p. 18) : " I consider it well
observe that no law of nature, however general, has
I established all at once; its recognition has always been
eded by many presentiments; the establishment of a law,
ever, does not take place when the first thought of it takes
1, or even when its significance is recognised, but only when
as been confirmed by the results of experiment which the man
icience must consider as the only proof of the correctness of
conjectures and opinions."

* Frinciplcs, 1905, Vol. II, p. 17.
OL. XCV. 6 Y

209-4 riLDEN : mendeli<;eff memorial lecj ure.

I regard it as unnecessary, in the presence of the Fellows of the
Chemical Society, to review with any detail the multitudinous
applications of the scheme of the elements constructed on the basis
of the periodic law. These arc the commonplaces of modern
theoretical chemistry. They are embodied in every text-book of
any importance, and are related by every lecturer and teacher as
familiar and indisputably recognised consequences of the system.
AVe may therefore pass lightly over the story of the prediction by
Meudeleeff of the properties of undiscovered elements, confirmed
so remarkably by the discovery of scandium, gallium, and ger-
manium, and related in dramatic language by Mendeleeff himself
(Faraday Lecture). ,We may also pass over the applications of
the system to the correction of atomic weights, illustrated by the
case of beryllium, the recognition of previously unnoticed relations,
and the discovery of new elements, notably the companions of
argon (Ramsay, Presidential Address to Section B, British Associa-
tion, 1897, and Froc. Itoy. Hoc, 1898, 63, 437).

It will be more profitable to consider a few of the difficulties
which still encumber the application of the law, and which, while
limiting our acceptance of it in an unqualified form as applicable
to the whole of the elements, tempt the speculative mind to wander
in wide fields of conjecture.

Can it be truly said that the elements arranged in the order of
their atomic weights show without exception periodic changes of
properties ? This question has been propounded already, but has
never been fully discussed, even by Mendeleeff. An examination
of the facts seems, how'ever, to indicate the possibility of some
other principle, which, while it does not supersede the periodic
scheme, would, if it could be recognisedj^ supplement it. This
involves other considerations which we may turn to fii'st.

If the whole of the known elements are drawn up in the order
of their atomic weights (using the values given by the International
Committee for 1908), we find'a progression in value from H = 1'008
to U = 238'5, with differences between the successive elements
which vary from O'S (Co — Ni)'^' to 4-3 (Co — Cu) among the

* Mendeleeff held the view that "in general, cobalt is more nearly allied to iron
than nickel, and the latter more nearly to copper" {Principles, Eng. Ed., 1905,
p. Zl^). Accordingly, in the first edition of his book, he assigned to cobalt the
atomic weight 58'5, and to nickel, the atomic weiglit 59. In the later edition of
1905, he makes them both 59, and expresses the belief that eventually the atomic
weight of cobalt will be found less than that now accepted and less than nickel
(Eng. Ed., 1905, II, footnote 25, p. 45j. "Whatever may be the exact values of the
atomic weights of these two elements, there can be no doubt that the atomic weight
of cobalt is yrcaler than that of nickel. This is proved by the estimations of the
specific heats of both these metals pui-ified by methods which preclude the possibility

TILDEN: MENDELEEFF MEMOHIAL LKCTtJRE. 2095

common elements of which the atomic "weights have been most
accurately estimated. The large difference, 7"4, between Sb and Te
is manifestly due to some error in the atomic weight of tellurium
of which no sufficient explanation is yet forthcoming, and it is
only when we get to the element Bi that there seems reason for
thinking that it must be followed by some hitherto unrecognised
elements, since the gap between Bi and the next known element,
Ra, is 18' 7 units. The atomic weights of the long series of elements
beginning with La are confessedly uncertain, but that they all lie
between La and Ta seems probable, because although the individual
numbers are doubtless inexact, the average difference between any
two consecutive terms is roughly the same as the average difference
between successive atomic weights among the better known
elements preceding thein. Ta — La = 181 — 138"9 = 42"1 for sixteen
intervals.

It must also be noted that the differences, approximately three
units each, among the three elements with smallest known atomic
weights, namely,

H 1-008, He 4, Li 7-03,
are greater than the differences observed among the elements which
immediately succeed them, namely,

Li 703, Be 9-1, B 11, C 12, N 14-01, O 16, F 19.

It will be seen later that, as regards this part of the scheme,
Mendeleeff had put forth a special hypothesis.

If these considerations are to be regarded as having weight, it
seems probable that few additional elements are to be expected,
except possibly one following Mo and another following W, save
in the region already indicated from Bi to Ra. This suggests the
remark that, after all, it is not necessary to assume that the
materials of which the earth consists should necessarily include a
samjile of every possible element indicated by such a scheme.
Some which are missing from terrestrial matters may perhaps be
responsible for phenomena recognisable by the spectroscope in stars
or nebulas far distant in cosmical space. The unexpected, however,
often happens, and, remembering the discovery of terrestrial

of appreciable error or of mutual contamination. The following results were
obtained by difforent observers using different methods :

Temperature. Cobalt. Nickel.

From 100° to 15° 0-10303 0-10842

15° to -78-4° 0-0939 0-0975

,, 78-4° to -182-5° 0-0712 0-0719

Tilden, Phil. Trans., 1900, 194 ^i, 249.

From 100" to -20° 0-104 0-108

Copaux, Compt. rend., 1905, 140, 657.

6 Y 2

2090 TiLDEN: mendel]i;eff memorial lecture.

helium, it is permissible to liope that some of the vacant spaces
may hereafter be filled by earthly occupants.

There is one important point to be noted here, namely, that if
the so-called rare earth metals, praseodymium, neodymium,
samarium, gadolinium, terbium, dysprosium, erbium, ytterbium,
and others of which the existence is doubtful, do lie in the position
indicated, the original statement of the periodic law breaks down
at this point. Enough is already known of their properties to show
that they are very closely allied together, and cannot fall into
separate periods. Mendeleeff says {Princijdcs, 1905, Vol. II, p. 45),
'' This appears to me to be one of the most difficult problems
offered to the periodic law." He prefers, however, to leave open
the question as to the position of these elements. The discordance
of argon and of tellurium with the places assigned to them are
also matters which must be left for the consideration of future
workers.

One result of the recognition of the periodic law is that theories
concerning the genesis of the elements have received a stimulus
previously unknown. It is, however, interesting to note the
attitude of Mendeleeff toward this question, and the small extent
to which this attitude ajDpears to have become modified with the
lapse of time. When, in 1889, twenty years after the discovery of
the law, he composed the Faraday lecture, he seems to have
regarded speculation in this direction as a kind of abuse of the
periodic system. He was, of course, fully justified in stating
(Faraday Lecture) that " the periodic law, based as it is on the
solid and wholesome ground of experimental research, has been
evolved independently of any conception as to the nature of the
elements; it does not in the least originate in the idea of a unique
matter; and it has no historical connexion with that relic of the
torments of classical thought." But it is at least questionable
how far he was justified in continuing that " therefore it affords
no more indication of the unity of matter, or of the compound
character of our elements, than the law of Avogadro or the law
of specific heats, or even the conclusions of spectrum analysis.
None of the advocates of a unique matter have ever tried to
explain the law from the standpoint of ideas taken from a remote
antiquity, when it was found convenient to admit the existence of
many gods and a unique matter." And again, later, " From the
foregoing, as well as from the failures of so many attempts at
finding in experiment and speculation a proof of the compound
character of the elements and of the existence of primordial matter,
it is evident, in my opinion, that this theory must be classed
among mere Utopias."

TILDEN: MEXDEM'iEFF MKMORIAT, LECTURE. 2097

Fifteen years later, after the discovery of the argon group of
elements, of the phenomena of radioactivity, and of radium, it
became necessary to consider the relations of these substances to
the periodic scheme. In a remarkable article contributed to the
new Russian Encyclopaedia, and subsequently printed as Appendix
III to the Prijicijdes (English Edition, 1905), Mcndeleeff gives
a new table of the elements, in which places are found, not only
for the argon group and radium, but for two hypothetical elements
which are placed before helium and designated x and y.

As this table may be assumed to represent his latest views
concerning the relations of the elements, it is here reproduced.*

The y in the table is supposed to be an analogue of helium, and
may be identified hereafter with " coronium," which has been
recognised in the sun's . coronal atmosphere. This gas would
have, according to Mendeleeff, a density about 0"2, and therefore
a molecular weight about 0'4, or about one-tenth that of
helium.

X is the " ether " of the physicist, for which Mendeleeff, dis-
regarding conventional views, supposes a molecular structure. He
also assumes that, like the argon group, this element is chemically
inert and possesses a very low density and atomic weight, estimated
at 0-000,009,000,053.

His views in connexion with this matter are put forward merely
as speculations and without dogmatism, but it is clear that he
retained his repugnance to the conception of a unique matter to
the last. In his essay entitled " A Chemical Conception of the
Ether " (translated by Kamensky, 1904), the following passage
occurs, p. 32 : " Being unable to conceive the formation of the
known elements from hydrogen, I can neither regard them as
being formed from the element x, although it is the lightest of all
the elements. I cannot admit this, not only because no fact points
to the possibility of the transformation of one element into another,
but chiefly because I do not see that such an admission would in
any way facilitate or simplify our understanding of the substances
and phenomena of nature."

Chemists and physicists have, however, found it impossible to
resist the fascination of this problem, and accordingly there have
been many hypotheses as to the origin of the elements and the
nature of their connexion with one another. These seem to be
inseparable from the periodic scheme itself, which at once provokes
the inquiry. Why do these numerical relations occur, and what

* The spaces left vacant in Series I, after hydrogen, are the positions of hypo-
thetical elements having approximately the atomic weights, 1'4, 1'8, 2'2, 2'6, 2'8,
3'0, and 3'4, and standing at the head of groups II to VIII respectively.

?oos

TII.DEX: MENDEI.l^EFF MEMORIAL LECTURE.

'A'A

rS II

o

oo

S

Pi

i I

^ 3

oo

p-

Pu

o

.So

-in ^ o

■ - lO

^S !^tt)

o

g-S =(N rS

OO

3 H -w M

.2S

r?^^

'Xi

5p S-,

^^

Jpll

►i^t3

O

c o

j^^ I

20h

.^vo

Sco

rt .-I
S II

I I U II l^

o o 3c -33 r; H

E CO

So

O

5 ^
.2 o

CM

hh

■M

CO s~

3 (M ^ "»< .2

-? -"O „^^

Oo

2 ■*

5 II -^ II

_2 -^ 2 II

HH

I ==

1. a>

o CQ

fee fco

J; «o ^ CO •- ^
•^11 § li I II

M =?

>>o

i: o

—I to

P5«

Ep
5 i^-

'? II "5.;:

^p c

0|

•2 II

P3

rt

<5

8i II
O J»

I ;22

O II

-'P

V 03

KM

^ Oi S CO

■<<

^00

T-l C-i

TILDEN: MENDEL1^:KFF MFMORIAL LECTURE. 2090

is the meaning of them if they do not point to a common genesis
or the operation of some process of evolution ?

Hypotheses concerning the evolution of tlie elements have hithcilo
been usually based on tlie assumption that the successive stages of
condensation of elemental matter proceeded from a single primary
stuff, which by a process analogous to polymerisation among carbon
compounds gave rise to atoms of greater and greater mass, which
were stable at the prevailing and any lower temperature. The
physical cause of the successive condensations is supposed to be a
falling temperature. It is, of course, possible to imagine that if
to the stuff of which hydrogen atoms consist are added successive
portions of matter of the same kind, stable structures may at
intervals result which we know as the atoms of the elements helium,
lithium, beryllium, boron, carbon, nitrogen, oxygen, and fluorine,
provided the idea of internal structure in these atoms is allowed.
Otherwise, from the mere accretion of matter upon a central
nucleus, there seems no sufficient reason why there should not
have been formed an indefinite number of intermediate masses
corresponding to an indefinite number of what would be called
elements. Further, it is difficult to understand why simple increase
of mass should change, say, oxygen into fluorine, while a further
addition of the same kind should change negative fluorine into
inert neon or positive sodium. The possibility of the condensation
of a single " protyl "so as to produce, at successive though unequal
stages of cooling, the elements known to the chemist has been most
ably discussed long ago by Sir William Crookes.

This hypothesis, however, was put forward long before the work
of Sir J. J. Thomson and his school was given to the world and
the electron was accepted as a physical reality. The hypothesis
that one elemental stuff may give rise to the whole array of
known elements by a process of condensation accompanied by a
loss or gain of electrons, the mass of which is approximately one-
thousandth of the mass of an atom of hydrogen, forms the subject
of a paper by Mr. A. C. G. Egerton in a recent number of our
Transactions (1909, 95, 239). The atomic weights calculated by
his formula agree closely with the experimental atomic weights
of the first fifteen elements, but the hypothesis gives no explanation
of the facts observed in the physical properties of the elements
arranged according to the Mendeleeff scheme, their alternation
of odd and even valency, the transition from positive on one side of
the table to negative on the other, the periodicity of properties
shown by the sudden change of character in passing from fluorine
to the next element, whether it be neon or sodium.

Another paper by Messrs. A. C. and A. E. Jessup {Phil. May.,

•2100 TIM>r\ : MENDELEEFF MEMORIAL LECTURE.

1908, [vi], 15. 21) luas recently provided a hypothesis of an entirely
different character. From a study of the spectra of the nebulae,
these authors have been led to assume the existence of two hitherto
unrecognised elements, to which the names protoghicinum and
protoboron are assigned. These with hydrogen and helium are
supposed to represent four initial substances, or protons, which, by
condensation directly or indirectly, give rise to all the rest of the
elements. The arguments of these authors are ingenious, but
rather artificial in view of the fact that the number of groups
in the periodic scheme to be provided for is greater than four.

In the Mendeleeff chart of the elements, there is nothins: more
striking than the gathering of the negative elements toward what
may be called the N.E., and the segregation of the positive elements
toward the S.W., the centre of the intermediate territory being
occupied by elements which play a more or less undecided part.
I have elsewhere (Presidential Address, 1905, Trans., 87, 564)
drawn attention to the fact that carbon, at any rate, is not directly
deposited by electrolysis from any of its compounds, with positive
hydrogen on the one hand, or negative chlorine on the other. I
believe the same is true of silicon, these two elements standing in
a middle position between the extremes occupied by lithium and
fluorine respectively.

If we assume that atoms are made up of two parts (protyls),
positive and negative, in proportions which determine by the
preponderance of one or the other whether the element shall exhibit
the positive character of a metal like lithium or the negative
character of a halogen, we arrive at a hypothesis which recalls
the ideas put forward nearly a century ago by Berzelius. His
views are familiar to every student of the history of chemistry,
but have long been relegated to the lumber room of worn-out
doctrine. The last few years have, hov/ever, given us the remark-
able experimental investigations of J. J. Thomson already referred
to, and the new conceptions concerning the nature of atoms, which
revive the fundamental idea that they are made up of two com-
ponents.*

* Camelley, in 1885 {Brit. Assoc. Reports), brought forward the idea "that the
elements are not elements in the strict sense of the term, but are, in fact, compound
radicals made up of at least two simple elements, A and B." The element A was
supposed to be identical with carbon, while to B was assigned a negative weight, - 2,
and it was suggested that it might be the ether of space. C. S. Palmer (Proc.
Colorado Scient. Son.) assumed the existence of two sub-elements, to which he gave
the names "kalidium" and "oxidium," and his views appear to have a general
resemblance to the hypothesis suggested in the text. The original article is abstracted
in Venables' Periodic Law and is referred to in footnotes in Palmer's translation of
Nemst's Theoretical Chemistry.

TILDES: MENDELT^:EFF MEMORIAL LECTURE. 2101

Setting out the known elements in the order of the numerical
value of their atomic weights, we find that between the first three
elements, H = l, He = 4, and Li = 7, the difference, 3, is greater
than would be expected by comparison with the difTerences noticed
between the elements of greater atomic weight which immediately
follow them. In order to satisfy the hypothesis just put forward,
there appears to be wanting an element which should stand in the
same relation to fluorine as hydrogen to lithium. This would
have an atomic weight 2' 7 approximately. Whether this exists,
and whether its existence is indicated by the unappropriated
spectral lines of nebuloe or corona, can only be a matter of con-
jecture. Mendeleeff, in his (1905) latest speculations concerning
the possibility of still undiscovered elements, has suggested the
existence of a new element of the halogen group with an atomic
weight about 3.* But, as already sufficiently shown, he accepted
no hypothesis which involved any idea of the composite nature
of the elements. It would therefore have been foreign to his
system to employ this element in any such manner. Bvit the idea
seems to me to assist materially conceptions as to the process of
condensation hypothetically occurring in the evolution of the
known chemical elements. Fcr to suppose that the typical
elements, so different as they are in character, forming the first
line of Mendeleeff's scheme, have all resulted from the condensation
of a single protyl has always seemed to me a difficult proposition.
There is comparatively little difficulty in the view that the succes-
sive terms of a family of what, by analogy, may be called a
homologous series, may have originated in this way. A con-
sideration of all the properties of the alkali metals, for example,
coupled with the character of their spectra, suggests quite naturally
the passage from lithium to sodium, and so forth, step by step,
by the addition of successive accretions of the same matter to the
primal element, the character of which, including valency, is not
only sustained through the whole family, but becomes more
strongly marked in proportion to the gradual increase of atomic
weight. At the opposite end of the table, on the other hand, a
reduction of the negative character of the element, in passing from
fluorine to iodine, seems to suggest that the negative protyl which
preponderates in the smaller atom is modified in the larger atom
by the addition of a certain proportion of the positive protyl.

The conceptions presented to iis in J. J. Thomson's work permit
of several supplementary hypotheses, especially the idea that if

* It may also, perhaps, be worthy of note that ]Mr. Egerton's calculations {loc.
cit.) lead him to postulate an element of nearly this atomic weight, namely, 2 "9844,
although his paper gives no indication as to its character.

21()2 TILDEN: MEXnELl^EFF MEMORIAL LECTURE.

atoms arc really made up of smaller corpuscles these are not thrown
together in confusion but, as he has shown, must be distributed
within the mass in a definite order, which is determined by the
attraction of the electropositive shell and the self-repulsion of
the negative corpuscles included in it. Once the idea of structure
within the atom is admitted, the possibility presents itself of there
being for the same mass more than one arrangement corresponding
to what is called isomerism in compounds. In this way the case
of elements with similar properties and identical or nearly identical
atomic weights, for example, cobalt and nickel, and even such a
case as tellurium, might perhaps be explained. Further, now that
the materials which have so long received the unsatisfactory
designation of the " rare earths " are found in unexpected
abundance, it may be hoped that the study of their chemical
characters may be completed. It may turn out that this group
may include elements of identical atomic weight, though exhibiting
different properties. It does not seem very long ago in the memory
of many now living that the nature of the isomerism of the
derivatives of benzene was a deep mystery, from which nearly all
obscurity cleared away in the light of the then new theory of the
constitution of benzene.

I have dwelt at some length on these various hypotheses, because
the discussion of the subject to which they relate indicates, in my
opinion, one of the consequences of the promulgation and general
acceptance of the periodic scheme of the elements. This is, how-
ever, not the only result of the recognition of its validity and
usefulness by chemists generally. That the elements stand in a
definite relation to one another implies that their compounds also
fall into their places in an orderly system, and consequently a basis
is provided for the complete systematisation of the whole science
of chemistry. There is scarcely a treatise on chemistry which does
not bear evident witness to this influence. And this is perhaps
not the least among the services rendered by this generalisation,
for not only is the learner enabled to remember a much larger
number of facts than previously, but he is led to perceive a
connexion between phenomena and processes which was almost
entirely wanting so long as practical chemistry consisted mainly
of a bundle of recipes. And here it is fitting that we should glance
at the famous treatise by Mendeleeff himself, " The Principles of
Chemistry," of which we possess three editions in English, the last
of which, issued in 1905, is a rendering of the seventh edition
(1903) of the original. An eighth Russian edition began to be
issued in 1905, bu€ is incomplete. To this remarkable book it is
impossible to do justice in a brief notice or to communicate to

TILDEN : MEXDELTsEFF MEMORIAL LECTURE. 2108

those who have not read it an adequate impression. Clearly it is
a work of genius, but such works are not always the most suitable
for beginners, though for the advanced student nothing can be
more inspiring. The " Principles " embody in reality two distinct
treatises, for the text, which is written in an easy style, open to
quite straightforward reading, is accompanied by notes which are
often more voluminous and usurp entire pages. Even the preface
is attended by these commentaries, which are all interesting as
showing the spirit of the writer and the restless activity of his
mind. A few extracts from the preface will serve to illustrate
the truism too often neglected by writers of biographies, that it is
impossible to separate a man's work from his life, and that the
character and quality of the former are dependent upon the
personal characteristics of the man, independently of the oppor-
tunities or influences which may have served to assist or to repress
his activities.

" If statements of fact," he says, " themselves depend upon the
persons who observe them, how much more distinct is the reflection
of the personality of him who gives an account of methods and
philosophical speculations forming the essence of a science ! For
this reason there will inevitably be much that is subjective —
bearing the stamp of time and locality — in every objective
exposition of science. And as an individual production is only
significant in virtue of that which has j^receded it and that which
is contemporary with it, it resembles a mirror, which in reflecting
exaggerates the size and clearness of neighbouring objects, and
causes a person near it to see reflected most plainly those objects
which are on the side to which it is directed, and sometimes even
the person holding the mirror. Although I have endeavoured to
make my book a true mirror directed toward the whole domain
of chemical changes and of the elements taking part in them, yet
involuntarily those influences near to me being most clearly
reflected and the most brightly illuminated have tinted the entire
work with their colouring. In this way the chief peculiarity of the
book has been determined. Experimental and practical data and
their application in life and industry occupy their place, but the
philosophical principles of our science form the chief theme of the
work."

Later on he says, " The thought that this book might fall not
only into the hands of the beginner for whom it is intended, but
also of authorities who might wish to know the views held by an
old disciple of science on the current problems of chemistry, greatly
complicated the preparation of a new edition, for it necessitated
making a selection of the most essential of the vast number of

2104 TiLDEX: mendeli':eff memorial lecture.

new researches published year by year and explaining my views on
them without greath^ enlarging the bulk of the work. After
having closely followed all the chief conquests of chemical science
siilce the days of Berzelius, Liebig, Dumas, and Gerhardt, and
having seen the triumph of much that lay neglected, and the fall
of much that was exalted, I involuntarily acquired a tendency to
analyse new facts, and a desire to transmit to my readers the
results of such analysis, if it could, in my opinion, help towards
a proper explanation and generalisation of the chemical elements.
In carefully prejDaring this edition, I have not lost sight of the
fact that I am hardly likely to publish another, and I have
therefore in many cases spoken more definitely than formerly.
After having been an insignificant but zealous worker in chemistry
for almost half a century, I wished my book should retain some
traces of how a confirmed disciple of Gerhardt regards the funda-
mental problems of the theory of the chemical elements at the
beginning of the twentieth century. As an example, I may
mention that the more I have thought on the nature of the
chemical elements, the more decidedly have I turned away .from
the classical notion of a primary matter, and from the hope of
attaining the desired end by a study of electrical and optical
phenomena, and the more clearly have I recognised that first and
foremost are needed truer conceptions of ' mass ' and ' ether ' than
those in vogue at the present time. The return to electro-
chemism which is so evident in the supporters of the hypothesis
of ' electrolytic dissociation,' and the notion of a splitting up of
atoms into ' electrons,' in my opinion only complicate, and in no
way explain, so real a matter (since the days of Lavoisier) as the
chemical changes of substances, which led to the recognition of
the invariable and ponderable atoms of simple bodies. The
definition of mass gave a means for analysing and grasping
chemical transformation of substances, and for arriving at the
atom, while the mass of the atom was shown by the periodic law
to influence all its chief chemical properties. Thus chemistry in
its principles stood on the firm foundations laid by Galileo, Newton,
and Lavoisier, and in order to gain further insight and knowledge
of the atoms themselves, the fundamental conceptions of mass,
gravity, and ether will have to be explained by a method of
experiment alone, otherwise the realism of science will again open
its doors to such metaphysical and ' metachemical ' conceptions as
phlogiston and other mystical dreams. For my part I endeavour
to remain true to the testament of realism left by Newton and
Lavoisier, and it is my wish to instil this sentiment into my young
readers."

TILDEN : MEXUEL^EFF MEMORIAL LECTURE. 2105

This is very clear, and little more remains to be said. In the
seventeenth century Robert Boyle taught us how to distinguish
elements from compounds, and how to give to the word " element "
a definite connotation clearly distinguishing it from the elusive
and fantastic language of the alchemists. In the eighteenth
century Lavoisier showed the true nature of the most familiar of
chemical compounds, namely, acids, bases, and salts, and helped
to lay the foundation of quantitative chemistry. At the beginning
of the nineteenth century Dalton gave to chemistry the Atomic
Theory, of which it is not too much to say that it provided the
scaffold by the aid of which the entire fabric of modern theoretical
chemistry has been built up. Sixty years later this conception,
developed and adorned by the labours of an army of earnest
workers, has been shown to us in a brilliant new light thrown
over the whole theory by jNIendeleetf.

The views of Boyle, of Lavoisier, and of Dalton have been
corrected by experience and broadened by extended knowledge, but
the fundamental and essential parts of their ideas remain, and
their names are immortal. In like manner the expression of the
periodic law of the elements as known to the present generation is
destined, we may believe, to be absorbed into a more comprehensive
scheme by which obscurities and anomalies will be cleared away,
the true relations of all the elements to one another revealed, and
doubts as to the doctrine of evolution resolved in one sense or the
other. But as with the Atomic Theory itself, there is no reason
to doubt that the essential features of the periodic scheme will
be clearly distinguished through all time, and in association with
it the name of Mendeleell will be for ever preserved among the
Fathers or Founders of Chemistry.

lM()(J SIMOXSKX AND STOllEY : SYNTHESES WITH THE

CCXW 1. — Syidlicses ivith the Aid of Monochloromcthyl
Ether. Part II. The Action of Monochloromethyl
Ether on the Sodiwn Derivative of Ethyl Aceto-
acetate.

By John Lionel Simonsen and Robert Storey.

Ix <a recent communication (Trans., 1908, 93, 1777) it was shown
that monoclilorometliyl ether readily condenses with ethyl sodio-
nialonate, with the formation of ethyl j8-methoxymethylraalonate,
and. since this substance exhibited rather striking properties, it
seemed a matter of some interest to investigate also the con-
densation of monochloromethyl ether and ethyl sodioacetoacetate.
It seemed probable that this reaction would lead to ethyl )8-methoxy-
mcthylacetoacetate, which it was hoped might, on hydrolysis with
acids, undergo internal condensation with formation of 1 : 3-di-
acetylryc/obutane, and thus throw further light on the stability
of the cyc^obutane ring :

OMe-CHgCl + CHgAcNa-COgEt — > OMe-CHo-CHAc-COaEt.
20Me-CH2-CHAc-C02Et —>

C02Et-CAc(CH2-OMe)-CH2-CHAc-C02Et —^ CHAc<p!?2>CHAc.

CH

On carrpng out the condensation in a manner similar to that
described in the previous communication, besides a substance of
high boiling point, an ester was isolated which was apparently
the expected substance, ethyl )3-methoxymethylacetoacetate. Con-
siderable difficulties were, however, at first encoixntered in attempt-
ing to examine the properties of this ester, owing to the ease with
which it is decomposed into acetone and formaldehyde. Satisfac-
tory results were, however, ultimately obtained on hydrolysis with
aqueous potassium hydroxide, when a beautifvilly crystalline acid,
C(;Hjq04, which melted at 105°, was obtained. Owing to the great
stability exhibited by this acid, it was, however, at once obvious
that it could not be a monosubstituted derivative of acetoacetic
acid. »

Now Claisen (Ber., 1892, 25, 1768) has shown that eth}'! chloro-
carbonate and ethyl sodioacetoacetate condense with the formation
of ethyl carboxyethylacetoacetate, and it therefore seemed probable
that a similar reaction had taken place in this case with the
formation of ethi/l methoxy-fi-methoxijcrotonate :
OMe-CH.Cl + NaO-CMelCH-COaEt — > OMe-CHg-O-CMelCH-COaEt.

Further investigation confirmed this view, and it was found that

AID OF MONOCIILOUOMETIIYL ETlIEli. PART II. 2107

the acid CcHjo04 showed in every way the properties of a substituted
crotouic acid. Mcthoay-fi-inclliojycrotonic acid is an acid of con-
siderable stability; it is readily distilled under diminished pressure,
and its potassium salt may be heated to 100° without any decom-
position taking place. When, however, it is treated with dilute
acids or heated with water in a sealed tube, it undergoes complete
disintegration, with formation of formaldehyde, acetone, and carbon
dioxide.

In order to obtain a still more definite proof of its constitution,
an attempt was made to oxidise it with ozone in a manner analogous
to that which Harries {Annalen, 1905, 343, 352) employed so
successfully in the case of crotonic acid. Unfortunately, however,
although a solid ozonide was obtained, no satisfactory product
could be isolated on decomjjosition with water, and only the
presence of acetic acid and an aldehyde, probably formaldehyde,
could be definitely proved.

Methoxy-;8-methoxycrotonic acid undergoes an interesting decom-
position when distilled under the ordinary pressure, two molecules
reacting with the formation of a substance which is probably
methoxymcthyl victlbo.cy-^-viethoxycrulonate, the reaction taking
place in accordance with the following scheme :

20Me-CH2-0-CMe:CH-COoH -^

OMe-CH2-b-CMe:CH-CO,-CH2-OMe + CHgAc-CO.^H.

In continuation of these experiments, many attempts were made
to produce a substance in which the monochloromethyl ether radicle
is attached to the carbon atom. It has been shown by Nef
(Ainialcn, 1893, 276, 200) that ethyl chlorocarbonate readily con-
denses with the copper derivative of ethyl acetoacetate with the
formation of ethyl acetylmalonate, and an attempt was therefore
made to obtain ethyl )3-niethoxymethylacetoacetate in a similar
manner. In this, however, we were unsuccessful, the sole product
of the condensation being ethyl ay-diacetylglutarate. It is not
difficult to account for the formation of this substance if it be
assumed that the process proceeds on the following lines. Ethyl
/3-methoxymethylacetoacetate is first formed, and this removes the
copper from a portion of the copper derivative of ethyl acetoacetate,
and the ethyl acetoacetate thus liberated combines with the ethyl
i8-methoxymethylacetoacetate with loss of methyl alcohol and
formation of ethyl oy-diacetylglutarate :

OMe-CHgCl-f-Cu-CHAc-COaEt -^ OMe-CHg'CHAc-COgEt.

OMe-CHg-CHAc-COoEt + CH2Ac-C02Et — >

COaEfCHAc-CHa-CHAc-COgEt.

From this experiment it seems improbable that ethyl )8-methoxy-

210S SIMONSEN AND STOREY: SYNTHESES WITH THE

luethylacetoat'etate is capable of existence in tlie presence of ethyl
acetoacetate, immediate condensation taking place.

Etlivl ay-diacetylglutarate has already been investigated by
Knoevenagcl (A7i7ialcn, 1894, 281, 94), who obtained it by the
condensation of ethyl acetoacetate and formaldehyde in the
presence of piperidine and other secondary bases. He does not,
however, seem to have been able to prepare.it in a pure state,
since he says that it decomposes when distilled even under
diminished pressure. We have found that this is not the case.
It has been mentioned above (p. 2106) that an oil of high boiling
point was obtained in the condensation of ethyl sodioacetoacetate
and monochloromcthyl ether, and this consists entirely of
Knoevenagel's ethyl ay-diacetylglutarate, which we have succeeded
in obtaining quite pure by repeated distillation. Its identity was
confirmed by the fact that on hydrolysis with dilute sulphuric acid
it was converted into l-methyl-Ai-c_;/f/ohexen-3-one, and when treated
with alcoholic ammonia it gave ethyl dihydrolutidinedicarboxylate.

It is a matter of some interest that ethyl dihydrolutidine-
dicarboxylate is also formed when pure ethyl methoxy-j3-methoxy-
crotonate is treated with alcoholic ammonia. In this case, the
ammonia must first hydrolyse the ethyl methoxy-j8-methoxy-
crotonate with the formation of formaldehyde and ethyl aceto-
acetate, which then recombine in the presence of the base with
separation of ethyl ay-diacetylglutarate, and this reacts in the
ordinary manner with the ammonia.

Experimental.

Condensation of Monochloromethyl Ether and Ethyl Sodioaceto-
acetate.

Finely-divided sodium (14 grams) was suspended in dry ether
(350 c.c), and eth}^ acetoacetate (81 grams) was gradually added.
When the vigorous reaction which takes place had completely
subsided (about two hours), nionochloromethyl ether (50 grams),
dissolved in an equal volume of dry ether, was slowly added, and
the reaction mixture well shaken and cooled. The sodium com-
pound rapidly dissolved, and in about five minutes a gelatinous
precipitate of salt separated. The next day water was added and
the ether separated, dried, and evaporated. The residual oil,
which, as is usually the case in condensations with monochloro-
methyl ether, had a strong odour of formaldehyde, was rapidly
fractionated under 14 mm. pressure.

After a small quantity of unchanged ethyl acetoacetate had
passed over (5 grams), the thermometer rapidly rose, and a large

AID OF MONOCHLOROMETHVL ETHER. PART II. 2101)

fraction distilled fairly constantly at 115 — 125°. As soon as the
temperature again began to rise, the distillation was stopped, and
the residue in the flask (36 grams) was reserved for later investi-
gation (see p. 2111).

The main fraction, boiling at 115 — 125°, was refractionated
several times, when it was found to distil at 109 — 110°/ 18 mm.
Yield, 40 grams :

0-1316 gave 0-2674 CO. and 0-0951 II.O. C = 55-4; H = 8-0.
C8HJ4O4 requires C = 55'l; H = 8-0 per cent.

Ethyl VKthn.ry-^-mcthorycrotonate is a colourless oil possessing
a slightly pungent odour. A solution of the ester in chloroform
rapidly absorbs bromine, with slow evolution of hydrogen bromide.

MetJioxy-^-wethoxycrotonic A c'nl, OMe-CHo-O-CMelCH-COoH.

Ethyl methoxy-;8-methoxycrotonate (5 grams) was mixed with
potassium hydroxide (5 grams) dissolved in water (25 c.c), and
heated on the boiling-water bath for four hours, when all the oil
had passed into solution. After cooling, the aqueous solution was
made faintly acid with hydrochloric acid, when a pale yellow solid
separated.* This was collected, drained on porous pcy'celain, and
purified by crystallisation from either ether or light petroleum :

0-1282 gave 0-2319 CO., and 0-0815 H.^O. C = 49-3; H = 7-l.
C^jHjqO^ requires C — 493; H = 6-9 per cent.

Methoxy-13-niethoxycrofonic acid separates from ether or light
petroleum in large, glistening, prismatic needles, which melt at
105°. It is readily soluble in ether, ethyl acetate, chloroform, or
boiling light petroleum, but only sparingly so in benzene. Its
sodium carbonate solution immediately decolorises a solution of
potassium permanganate.

When a solution of the acid in chloroform is treated with a
chloroform solution of bromine, the bromine is rapidly absorbed,
but in a short time hydrogen bromide is evolved, so that it was
found impossible to isolate the bromo-acid.

The silver salt separates from a faintly alkaline solution of
the ammonium salt in glistening needles, which are readily soluble
in hot water. A recrystallised specimen, dried at 100°, gave the
following results on analysis :

0-1776 gave 0-1887 COo, 00579 H^O, and 0-0757 Ag. 0 = 289;
H = 3-6 ; Ag = 42-6."

0-1213 gave 00515 Ag. Ag = 42-5.

CcHgO^Ag requires 0 = 284; H = 3-6; Ag = 42-7 per cent.

* A further quantity of tliis acid may be obtained by extracting the filtrate with
ether.

VOL. xcv. G z

2110 RIMONSEN AND STOREY: SYNTHESES WITH THE

Since methoxj'-jS-metlioxycrotonic acid should exist in cis- and
trans-iorms, careful search was made with the view of isolating
the other form of this acid. The porous tiles on which the crude
acid had beeu drained were extracted in a Soxhlet apparatus
with ether, when an oily acid was obtained which could not be
obtained crystalline. It seems possible that this oil contained a
mixture of the stereoisomerides, since on distillation it gave a
good yield of methoxymethyl methoxy-)8-methoxycrotonate (see
below).

Esterification of Meilioxy-^-mellioxycrniomc Acid. — When
methoxy-)8-methoxycrotonic acid is treated in the usual manner
with alcohol and sulphuric acid or with an alcoholic solution of
hydrogen chloride, decomposition takes place, and only a very
small amount of the ethyl ester is obtained, the main product being
ethyl acctoacetate.

It was, however, readily obtained in a pure state by the action
of ethyl iodide on the silver salt of the acid. The silver salt (12
grams) was suspended in dry ether (100 c.c), and ethyl iodide
(12 grams) was added, and the solution heated on the steam-bath
for three hours. After filtering from the silver iodide, the ether
was removed, and the pure ester was found to boil at 109°/ 18 mm. :

0-1909 gave 0-3836 COo and 0-1577 H2O. C = 54-8; H = 8-0.
C8H;[404 requires C = 55-l; H = 8-0 per cent.

The instability of this ester was clearly shown by the following
experiment. The pure ester (5-26 grams) was dissolved in alcohol,
and the solution saturated with dry ammonia. After twelve hours
the alcohol was evaporated, when a semi-solid mass was obtained.
This was drained on jDorous porcelain, and the solid (0-45 gram)
was found to consist of ethyl dihydrolutidinedicarboxylate,

Methoxymethyl Methoxy-fi-methoxycrotonate,
OMe-CHg-O-CMelCH-COs-CHs-OMe.

It has already been mentioned in the introduction that methoxy-
/3-methoxycrotonic acid may be distilled quite readily under
diminished pressure (34 mm.), when it passes over with very slight
decomposition at 158 — 160°. When, however, it is distilled under
the ordinary pressure it is decomposed, some carbon dioxide being
evolved, and an oil slowly passes over, the thermometer gradually
rising to 220°. The oil was carefully purified by repeated distil-
lation under 20 mm. pressure, when it was found to boil at
131—132°:

0-1215 gave 0-2252 COg and 00805 HoO. C = 50-6; H = 7-4.

0-0949 „ 0-1770 CO2 „ 0-0664 HgO. C = 50-9; H = 7-8.
CgHi405 requires C — 505; H = 7-4 per cent.

All) OF MONOCHLOROMETtlYL ETHER. PART II. 2111

From the above analytical data, it seems probable that this oil
consists of met hoxy methyl metJioxy-^-mctlioxycrotonatc. It is a
colourless, mobile oil possessing a jileasant ethereal odour. Its
solution in chloroform readily absorbs bromine, and in a quan-
titative experiment it was found that 03738 gram absorbed 0"9
gram of bromine, whereas an unsaturated substance, CgHj^O^,
should absorb 093 gram.

The correctness of the above constitution is supported by the
fact that when the ester was hydrolysed by aqueous potassium
hydroxide, a quantitative yield of metlioxy-jS-methoxycrotonic acid
was obtained.

Decomjiosition of MetJwx^y-^-methoxycrotonic Acid into Acetone
and Formaldehyde. — Methoxy-j8-methoxycrotonic acid (3 grams)
was mixed with water (10 c.c), and heated in a sealed tube for five
hours at 140 — 150°. On opening the tube, much carbon dioxide
was evolved, but only a small amount of tar had separated. The
aqueous solution was distilled in steam, when a strong odour of
formaldehyde was noticed, and an immediate reaction was obtained
with Schifl's reagent. The steam distillate was treated with an
acetic acid solution of 2^-hromophenylhydrazine, when a yellow
precipitate separated. This was collected and purified by crystal-
lisation from light petroleum, from which it separated in yellow
needles, melting at 91 — 93°. No alteration in the melting point
was noticed when it was mixed with a specimen of acctone-2>bromo-
phenylhydrazone obtained from a different source.

Oxidation of Mcthoxy-^-methoxycrotonic Acid. — The acid (2
grams) was dissolved in chloroform, and the solution treated for
some hours with ozone. On removing the solvent in vacuum, a
solid ozonide sejDarated. This was decomposed by warming with
water and the aqueous solution extracted with ether, the ether
dried and evaporated, when a colourless oil remained. The oil
gave an immediate precipitate with phenylhydrazine and ^J-bromo-
phenylhydrazine, but all efforts to isolate a pure substance were
unsuccessful; only the presence of acetic acid and formaldehyde
could be definitely proved.

Ethyl ay-DiacetyUjlutarate, CO.Et-CHAc-CHs-CHAc-COgEt.

I. It has already been mentioned (p. 2109) that when the con-
densation product of monochloromethyl and ethyl sodioacetoacetate
is fractionated, a heavy oil remained in the distilling flask, which
apparently decomposed on distillation even under a very low
pressure. It was, however, found that when it was rapidly distilled
in small quantities it could readily be obtained in a pure state,
and boiled quite constantly at 178°/ 10 mm.:

G z 2

'211 '2 SYNTHESES WITH THE AID OF MONOCHLOROMETHYL ETHER.

0-1154 gave 0-243 COo and 00758 HoO. C-57-5; H = 7-3.

CjgHooOg requii-es C = 57-3; H = 7-3 per cent.
Ethyl ay-diacetylglutarate, whicli has not previously been
obtained in a pure state, is a viscous oil possessing a slight odour
reminiscent of ethyl acetoacetate. Its alcoholic solution gives an
intense purple-violet coloration with ferric chloride.

That this substance consisted of ethyl ay-diacetylglutarate was
shown by the fact that on ti-eatment with alcoholic ammonia it was
converted quantitatively into ethyl dihydrolutidinedicarboxylate,
which melted at 174 — 176° (compare Knoevenagel, loc. cit.).

The identity was further confirmed by hydrolysis with 10 per
cent, sulphuric acid, when l-methyl-A''-cy(?/ohexen-3-one was obtained,
which boiled, as stated by Knoevenagel, at 200 — 201° :
0-1419 gave 03952 CO. and 0-1175 HgO. C = 76-0; H = 9-2.

CjHjqO requires C = 76-4; H = 9-l per cent.
The semicarhazone of l-methyl-A^-cj^c/ohexen-S-one, which does
not appear to have been jjreviously obtained, separates from water
in irregular plates, melting at 201° :

01285 gave 0-2731 CO., and 00901 H.p. C = 57-9; H = 7-8.

C3HJ3ON3 requires C = 57-5; H = 7-8 per cent.
II. For reasons which have already been given in the intro-
duction, the condensation of monochloromethyl ether and the
copper derivative of ethyl acetoacetate was investigated, and was
found to give an excellent yield of ethyl oy-diacetylglutarate.

The copper derivative of ethyl acetoacetate (32 grams) was
suspended in dry ether (200 c.c), and monochloromethyl ether
(16 grams) was added all at once. No reaction took place for
some time, but later the green colour of the ethereal solution
gradually disappeared, and the mixture became slightly warm.
After remaining overnight, the cupric chloride was separated, and,
after removing the ether, the residual oil was fractionated under
20 mm. pressure, when it distilled at 193 — 195°. That this sub-
stance consisted of ethyl ay-diacetylglutarato was proved by its
conversion into ethyl dihydrolutidinedicarboxylate, melting at
174—176°.

Much of the expense of this research has been met by a grant
from the Research Fund Committee of the Chemical Society, for
which the authors are much indebted.

The UNivEftsMY,

Manchester.

SYNTHESES IX THE EPINEPHRINE SERIES. 2113

CCXXVII. — Si/nfhcses in the Epinephrine Seriei^.

By Frank Tutin, Frederic William Caton, and
Archie Cecil Osborn Hann.

Inasmuch as the ])asc epinephrine, which possesses a constitution
represented by formuL^ I (Jowett, Trans., 1904, 85, 192), has so
valuable a physiological action, it appeared to be of considerable
interest to prepare certain substances related to it, in order that
their properties might be physiologically investigated:

Hq_

HO^ ^•CH(OH)-CH2-NH-CH3

~~ (I.)

It is already known that the ketone corresponding with
epinephrine is physiologically active, as are also the primary amines
(II and III) corresponding with both these compounds :
H0_ H0_

H0<^ ^•CH(OH)-CH2-NH2 H0<^ ^-CO-CHg-NHa

~ (11.) ~(III.)

We therefore endeavoured to prepare bases analogous to the
above-mentioned primary amines, but which would contain only
one hydroxyl group in the benzene nucleus. This attempt has been
successful, in so far as the para-derivatives are concerned, for
^-^-dihydroncy-^-jjJienylethylamine (IV) and the corresponding
ketone (V) have been obtained :

ho/ ^•CH(OH)-CH2'NH2 H0<^ "^-CO-CHj-NHg

^' (IV.) ~ (V.)

The physiological action of these substances has been investigated
by Dr. H. H. Dale, Director of the Wellcome Physiological Research
Laboratories, to whom we now express our thanks. It has thus
been ascertained that both the bases (IV and V), when injected
intravenously, have a pronounced influence on the blood-pressure.
The intensity of the action of the keto-base is of the same order
as that of the ketone corresponding with epinephrine, and it causes
about one-tenth of the rise in blood-pressure produced by an equal
weight of jS-p-hydroxyphenylethylamine, HO-CoH^-CHo-CHg-NHg
(Barger, this vol., p. 1123). The reduction of the ketonic group in
the monohydroxy-base (V) is, however, not attended with that
enormous increase in activity which is observed when the ketone
.corresponding with epinephrine is reduced, as jS-^J-dihydroxy-

2114 TUTIN, CATON, AND HANN :

/S-pbenylethj'lamine (IV) possesses only aboitt twice the activity of
its corresponding ketone. The action of the reduced base is, how-
ever, qualitatively far more like that of epinephrine than is that
of the ketonic compound.

The first synthesis of epinephrine to be described was conducted
according to the following scheme (D.R.-P. 152814, 155632, and
157300):
OH OH OH OH

OH _^ ,/ ^0H _^ - ^OH _^ f ^0H

CO CO CH-OH

CHgCI CH/NHMe CH^-NHMe

We therefore endeavoured, in the first place, to prepare P-jJ-di-
hydroxy-)8-i3henylethylamiiie (IV) by a similar series of reactions,
but with the employment of phenol, instead of catechol, as the
initial material.

Ivunckell and Johannssen {Ber., 1898, 31, 169) prepared
w-chloro-p-hydroxyacetophenone by the action of chloroacetyl
chloride on anisole in the presence of an excess of aluminium
chloride, but they failed to obtain the desired compound directly
from phenol. The present authors, however, find that the chloro-
ketone can be formed from phenol by means of the Friedel-Crafts
reaction if nitrobenzene be employed as the solvent. The yield
obtained by this method is, however, but small. The above-
mentioned authors (loc. cit.) have shown that w-chloro-p-hydroxy-
acetophenone chloroacetate is formed by the action of aluminium
chloride and chloroacetyl chloride on phenyl chloroacetate. The
present authors therefore sought to obtain the corresponding acetate
in an analogous manner from phenyl acetate, as the former com-
pound would serve equally as well as the hydroxy-ketone, from which
it is derived, for the preparation of the desired amine, and the
use of the relatively costly anisole would thus be avoided. It was
found, however, that when a mixture of phenyl acetate and chloro-
acetyl chloride is treated with aluminium chloride, the acetyl group
wanders into the para-position, and its place is taken by the chloro-
acetyl radicle, the resulting compound being '^-Ihydroxyaceto'phenone
chloroacetate (m. p. 73 — 74°). We therefore prepared w-chloro-
23-hydroxyacetophenone according to the method of Kunckell and
Johannssen.

It was found impossible to obtain w-amino-p-hydroxyaceto-
phenone from the chloro-ketone by condensation with ammonia,
although tlie experiment was conducted under a great variety of
conditions. Attempts to prepare the corresponding methyl

SYNTHESES I\ THE EPINEPHRINE SERIES. 2115

derivative from methylamine were also unsuccessful. This result
was somowliab surprising, as the corresponding dihydroxyplienyl-
methylamino-ketonc is formed in an analogous manner without
much difficulty (D.R.-P. 155632). The only definite product that
could be obtained by the action of ammonia on (D-chloro-p-hydroxy-
acetophenone was an additive compound, IlO'Calli'CO'CHoCljNHg.
The desired base, (ji-amino-^-hydroxyaceto'phenone (m. p.
190 — 193°), was, however, eventually obtained in the following
manner. o)-Chloro-]i-acetoxi/acetophetio?ie (m. p. 89 — 90°) was
heated with potassium phthalimide, when the phthcdijl derivative,

OAc-CaH,-CO'Cir,-N<^^>CVH,

(m. p. 174°), was obtained. This condensation product was then
heated with concentrated hydrochloric acid, when (a-amino-
T^-hydroxyacetophenone hydrochloride was generated. The free base
obtained from this salt crystallises well, and is quite stable in the
absence of oxygen, a behaviour which is not at all in agreement
with the statement of Gabriel {Ber., 1908, 41, 1128) that a-amino-
ketones of this type cannot exist in the free state.

The next step was to reduce the ketonic group contained in the
above-described base, in order to obtain the final prodvict. It was
found, however, that this could not be accomplished in a manner
analogous to that by which epinephrine was obtained from, its
corresponding ketone, namely, by the action of aluminium amalgam.
The behaviour of other reducing agents was therefore investigated,
when it was found that the desired result was attained by the
use of sodium and alcohol. The jS-^J-dihydroxy-jS-phenylethylamine
(IV) so obtained darkened and absorbed oxygen rapidly on exposure
to the air, and could not be crystallised, and this was also the
case with its hydrochloride. It readily yielded, however, a crystal-
line trihenzoyl derivative (m. p. 182°), by means of which the
identity of the substance was verified.

At the stage in this work when it was found that the desired
ketonic base could not be obtained by the action of ammonia on
the corresponding chloro-compound, it was thought that the object
might be attained by the method first employed by Jowett (Trans.,
1905, 87, 967) for syntheses in the epinephrine series, which has
since been used with some success by others (Bottcher, Ber., 1909,
42, 253; Pauly and Neukam, Ber., 1908, 41, 4151; Mannich and
Jacobson, Chem. Zeitsch., 1909, 33, 923). For this purpose we
endeavoured to prepare a-hydroxy-j^methoxy-a-pheuylethane, in
order that, by the elimination of water from this compound,
2;-vinylphenol might be obtained. jj-Hydroxyacetophenone was
therefore reduced, but this only resulted in the formation of a

2116 TUTIN, CATOX. AND HANN :

pinaconc (m. p. 207 — 208°). "We then prepared a-^-lnjdroxrrphenyl-
ethylamine by the reduction of j^-hydroxyacetopheuoneoxime. The
base was subsequently heated with nitrous acid, biit the resulting
product, which presumably contained a-p-dihydroxy-o-plienylethane,
was very unstable when exposed to the air, rapidly yielding
acetaldehyde and a brown resin.

o-j;-Hvdroxvphenylethylamine possesses special interest, inasmiich
as it was found to have a physiological action similar to that
exerted by its )8-isomeride, which has been shown by Barger {Joe.
cit.) to be one of the active principles of ergot. The naturally
occurring compound is, however, very considerably more active.
An attempt was furthermore made to prepare j^-vinylphenol by
the di-y distillation of jj-coumaric acid, under the same conditions
as lead to the formation of the corresponding ortho-compound (Ber.,
1908, 41, 367), but only polymerised jDroducts could be obtained.

As we were unsuccessful in preparing p-vinylphenol, p-vinyl-
anisole (Klages, Ber., 1903, 36, 3590) was employed. From the
latter, the dihromide (m. p. 80 — 81°) was obtained, and this, by
means of aqueous acetone, was converted into the hromohydrin,
MeO-C,,H4-CH(OH)-CH.^Br, which is a liqiiid. No satisfactory
method, however, could be devised of converting the latter com-
pound into the corresponding amine, the yields of basic product
being extremely small. It is interesting to note that on treatment
with acetyl chloride, the ' hydroxyl group in the bromohydrin is
replaced by chlorine, the resiilting a-cJdoro-fi-hro)uo-Yi-metJioxy-
a-phenylethane, MeO*C^Hj'CHCl'CH.2Br, being a solid, melting at
39 — 40°. It has been stated by Muset {Bull. Acad. my. Belg.,
1906, 775) that the replacement of hydroxyl by chlorine through
the agency of acetyl chloride is characteristic of tertiary alcohols,
but the above change shows that this is not always the case.

Some experiments were also made with the object of obtaining
ortho- and meta-compounds corresponding with the above-described
)8-j;-dihydi-oxy-i8-pheuylethylamiue. o-Yinylphcnol was prepared by
the dry distillation of o-coumaric acid, but no dibromide could be
obtained from it. ??i-Vinylphenol was prepared from m-n\txo-
cinnamic acid, according to the method of Komppa {Ber. lief.,
1893, 26, 677), but the yield of the final product was so small that
we did not proceed further in this direction. The derivatives of
7«-aminostyrene thus obtained did not, however, agree in their
properties with the corresponding substances described by Komppa
{loc. cit.). The last-mentioned author appears to have regarded the
hydrochloride and benzoyl derivative as being anhvdrous, and
stated that the latter substance fused at 90—91°. These com-
pounds, as prepared by the present authors, do not crystallise

SYNTHESES IN THE EPINEPHllINE SERIES, 2117

except with one molecule of water, and melt respectively at 181°
and 126—127°.

Experimental.
vi-Chloro-T^-hydroxyacetojjhenone.

Kunckell and Johannssen (Ber., 1898, 31, 167) prepared w-chloro-
2^hydroxyacctopllenone by the action of chloroacetyl chloride and
excess of aluminium chloride on anisole, but, when they attempted
to obtain it directly from phenol, the experiment resvilted in the
formation of phenyl chloroacetate, and subsequently of w-chloro-
p-hydroxyacetophenone chloroacetate. With the object of obtain-
ing from phenol the acetate corresponding with the last-mentioned
compound, the present authors treated phenyl acetate with chloro-
acetyl chloride and aluminium chloride.

Thirteen grams of phenyl acetate and an equal weight of chloro-
acetyl chloride were dissolved in carbon disulphide, and treated
with 17 grams of powdered aluminium chloride. After heating
the mixture for six hours, the solvent was removed, and ice and
dilute hydrochloric acid were added. The jDroduct was then
extracted with ether, when, on removing the solvent, a light green
oil was obtained, which became partly solid when stirred with light
petroleum. The solid was drained on a tile, after which it
was recrystallised from benzene, when colourless needles, melting
at 73—74°, were obtained :

0-1869 gave 0-3850 COo and 00729 HoO. C = 56-2; H = 4-3.

C10H9O3CI requires C = 56"5; H = 4'2 per cent.
That this compound was p-hi/droxyacetophenone chloroacetate
was evident from the fact that, on treatment with ammonia, it
yielded ^^hydroxyacetophenone and the base,

NHo-CO-CHo-NH-CHo-CO-NHo,
which was obtained by Heintz by the action of ammonia on ethyl
chloroacetate (^Annalen, 1868, 148, 177). It is evident, therefore,
that the acetyl group had wandered into the para-iDosition, its
place being taken by the chloroacetyl radicle.

In view of the statements of Behn (D.R.-P. 95901), we attempted
to obtain w-chloro-^j-hydroxyacetophenone directly from phenol by
means of aluminium chloride, but with the use of nitrobenzene as
a solvent. Although this operation was successful, the yield was
so small that we returned to the original method of Kunckell and
Johannssen (loc. cit.), using, however, an improved means of
isolating the product.

Twenty grams of anisole and 24 grams of chloroacetyl chloride
were dissolved in carbon disulphide, and 60 grams of aluminium
chloride gradually introduced. After heating for about four hours,

2118 TUTiy, CATON, AND HANN :

the solvent was removed, the residue treated with ice and hydro-
chloric acid, and the product extracted with ether. The ethereal
liquid thus obtained was shaken with a solution of ammonium
carbonate, which removed a small amount of brown product, after
which it was treated with aqueous sodium carbonate. This
removed the w-chloro-^^-hydroxyacetophenone in a state of relative
pitrity. During these operations a most severe irritation of the
eyes and face was experienced. This was found to be due to the
formation of a small amount of (a-chloro-o-methoxyacetopJienone, a
substance which will be described in a subsequent communication.
The sodium carbonate extracts were acidified, and the precipitated
product crystallised from methyl alcohol, when co-chloro-jj-hydroxy-
acetophcnone was obtained in the form of light yellow laminae,
melting at 148°.

Action of Ammonia and Methylamine on (d-C hloro-p-hydroxi/acetO'

'phenone.

A quantity of a)-chloro-2J-hydroxyacetophenone was dissolved in
alcohol, and a solution of ammonia in absolute alcohol added. The
mixture became red, some heat being developed, and a crystalline
substance soon separated. The latter was collected, and recrystal-
lised from an alcoholic solution of ammonia. It was then found
to be an additive compound of the chloro-ketone and one molecule
of ammonia, the latter being held only rather loosely:

03010, dissolved in alcohol, neutralised 16-0 c.c. iV/10-H2SO4. .
NH3 = 90.

C8H703C1,NH3 requires NH3 = 91 per cent.

On keeping this substance for any considerable length of time in
contact with acj^ueous or alcoholic ammonia, or on heating it with
either of these reagents, only red, tarry products resulted. This
was also the case when only the theoretical amount of ammonia
was employed. Analogous experiments, conducted with the use of
methylamine, likewise resulted only in the formation of red,
amorphous products.

Condensation of ta-Gliloro-'^-acetoxyaceto'phenone with Potassium

Phthalimide.

Since it was found impossible to obtain an amine from the
chloro-ketone by condensation with ammonia, recourse was had to
the use of potassium phthalimide. It was found necessary, how-
ever, to employ the acetyl derivative of the chloro-ketone, since the
original substance was so acidic that it decomposed the pota.ssium
phthalimide.

I

SYNTHESES IN THE EPINEPHRINE SERIES. 2119

cj-Chloro-;;-liydroxyacetophenonc was boiled for one hour with
acetic anhydride, and the resulting:; acetylatod product purified by
distillation. la-CJiloro-T^-acntoxyacetoyhcrione crystallises from
alcohol in large prisms, which melt at 89 — 90° :

0-1553 gave 0-3218 CO. and 00592 lip. C = 56-5; n = 4-2.
CjoHfjOjCl requires C = 56-5; H = 4-2 per cent.

After numerous experiments, the following method of condensing
the acetyl derivative of the chloro-ketone with potassium
phthalimide was found to be the best, a yield of phthalide
dei'ivativc amounting to about 42 per cent, of that theoretically
possible being obtained. (j-Cliloro-jj-acctoxyacctophcnono was
heated in a nickel crucible to 120 — 125°, when a molecular pro-
portion of finely-powdered potassium phthalimide was gradually
introduced, with constant stirring. The mixture, which was at
first quite fluid, gradually became viscid, and, after being main-
tained at the above temperature for about half an hour, was
completely converted into a brown solid. The latter, after being jdow-
dered, was extracted in a Soxhlet apparatus with boiling benzene.
On concentrating the benzene extract, the condensation product,
together with phthalimide, separated in crystals. The solid was
collected, washed with benzene, and freed from phthalimide by
repeated extraction with boiling water, after which the phthalide
derivative was crystallised from alcohol. It then formed slender,
colourless needles, melting at 174°:

0-1476 gave 0-3627 CO^ and 0-0574 HgO. C = 67-0 ; H =4-3.

0-3785 „ 14-8 c.c. N, (moist) at 20-8° and 766 mm. N = 4-5.
CigHisO.^N requires C = 66-9; H = 4-0; N=:4-3 per cent.

2)-Acetoxt/-(o-phfhaliimnoacetophenone,

AcO-C6H,-CO'CH2-N<^^>C6H„

is rather sparingly soluble in alcohol, but more readily soluble in
benzene, ethyl acetate, or glacial acetic acid. It is insoluble in
water or light petroleum.

(ji-A?n4no-'p-hi/droxi/acetophenone.

The above-described phthalide derivative (2 parts), together with
glacial acetic acid (15 parts) and concentrated hydrochloric acid
(50 parts), was heated in sealed tubes t-o 130° for three hours.
The contents of the tubes, which had become brown, were united,
concentrated under diminished pressure, and freed from phthalic
acid by extraction with ether. The liquid was then treated with
animal charcoal, filtered, and evaporated to dryness under
diminished pressure, as it is necessary to avoid the access of air

2120 TUTIN, CATON, AND HANN :

so far a-s possible. The dry residue was dissolved in alcohol, and
after some time isi-amiTU)--^-hyrlroxyaceto'phe7io7ie hydrochloride
separated in pink prisms, which were obtained colourless by further
recrvstallisation from alcohol. This hydrochloride dissolves very
readily in water, but only moderately so in alcohol, and not at
all in ethyl acetate. It has no definite melting point, but decom-
poses at 245—252° :

0-2644 gave 0-1982 AgCl. Cl=18-6.

CgHgOaNjHCl requires CI = 18-9 per cent.
w-A7}iino-p-hydroxyacefopheno7ie was obtained from the aqueous
solution of its hydrochloride by precipitation with sodium carbonate.
It forms colourless plates, which melt and decompose at 190 — 193° :
0-0982 gave 0-2278 CO2 and 0-0546 HoO. C = 63-4; H = 6-2.
0-1137 „ 0-2660 CO2 „ 0-0644 H2O. C = 63-8; H = 6-3.

CgHgOoN requires 0 = 636; H = 6-0 per cent.
It is only with difficulty that this base can be obtained colourless,
as in contact wdth air and moisture, especially in alkaline solutions,
it rapidly acquires a brilliant pink colour. It is readily soluble
in both acids and alkali hydroxides, very sparingly so in water,
alcohol, or ethyl acetate, and insoluble in chloroform or ether. It
yields a 'picrate, which crystallises in needles, melting at 192°, but
its gold and platinum salts were too soluble to admit of their
isolation.

(ji-BenzoT/lamino-])-henzo7jloxyaceto'phenone,
BzO-C^H4-CO-CH2-NHBz,
was prepared by the Schotten-Baumann method. It forms colour-
less needles, melting at 173 — 174°:

0-0992 gave 0-2685 CO2 and 0-0439 H2O. C = 738 ; H = 4-9.
C22H17O4N requires C = 73-6; H = 4-7 per cent.

^-'^-Dihydroxy-fi-'phenyl ethyl amine.

Attempts were first made to reduce w-amino-^^-hydroxyaceto-
phenone by means of aluminium amalgam, in a manner similar to
that by which epinephrine has been obtained from its correspond-
ing ketone (D.R.-P. 157300), but, although some change was
effected by this means, the desired result was not attained. It
was found, however, that sodium and boiling alcohol is a satisfactory
reducing agent for this purpose.

Five grams of w-amino-jj-hydroxyacetophenone hydrochloride
were dissolved in 250 c.c. of absolute alcohol in a flask attached
to a reflux condenser, and 30 grams of metallic sodium gradually
introduced in small pieces, under such conditions that the liquid
was kept in a state of rapid ebullition. When the metal had

SYNTHESES IN THE EPINEPHRINE SERIES. 2121

dissolved, the mixture was quickly cooled, after wliicli concentrated
hydrochloric acid was added until the liquid ceased to be alkaline
to litmus. The precipitated sodium chloride was then removed, the
filtrate evaporated to dryness under diminished pressure, and the
residue extracted with al)solute alcohol. In this way, the remaining
small amount of sodium chloride was removed. The alcoholic
extracts were concentrated, ethyl acetate added, and the resulting
mixture again evaporated. A relatively small amount of the
unchanged hydrochloride then separated in a crystalline condition,
and was removed. The filtrate contained a hydrochloride, wliicli
was nearly insoluble in ethyl acetate, but could not be induced to
crystallise. When dissolved in water, this salt absorbed oxygen,
even at the ordinary temperature, and this change occurred rapidly
on eva23orating the aqueous solution with the aid of heat. On
rendering ^he solution of the salt alkaline with sodium carbonate,
a base was precipitated, but this substance, like its hydrochloride,
could not be crystallised, and it rapidly absorbed oxygen. The
identity of this base as ^-"^-dihydroxy-^-iihenyltthylamine was,
however, proved by means of its benzoyl derivatives.

A qviantity of the aqueous solution of the reduced hydrochloride
was bcnzoylated by means of the Schotten-Baumann reaction. The
product so obtained was crystallised from alcohol, when it melted
at 145 — 175°, and obviously consisted of a mixture. By crystallisa-
tion from benzene, it was ultimately separated into two substances,
the more readily soluble of which formed slender needles, melting
at 182°:

0-0999 gave 0-2737 COo and 0-0461 H.O. C = 74-7; H = 5-l.
C09H03O5N requires C = 74-8; H = 4-9 per cent.

0-3110 in 30-6 of nitrobenzene gave A^- 0-170°. M.\V. = 419.
0-3572 „ 35-0 „ „ „ A<- 0-170°. M.W.=420.

C29H.3O5N requires M.W.=465.

It is evident from the above results that this substance was
the trihenzoyl derivative of fi-p-dihydroxy-P-pJienylethylamine,
BzO-Cr,H4-CH(OBz)-CHo-NHBz, the molecular weight deter-
minations clearly showing that it could not be a derivative of a
pinacone.

The more sparingly soluble constituent of the above-described
mixture melted at 210°, and, when pure, formed glistening leaflets,
which were nearly insoluble in benzene. It proved to be a
dihenzoyl derivative corres^Donding with the above-mentioned tri-
benzoyl compound, since it readily yielded the latter on further
treatment with benzoyl chloride. Moreover, since the tribenzoyl
derivative, when boiled with 80 per cent, alcohol, yielded this

21l!2 TUTIN, CATON, ANt) HANN :

dibenzoyl coinpoiind, melting at 210°, it would appear that the
latter possesses the structure BzO-C(;H4-CII(OH)-CH2-NHBz:

01017 gave 0-2736 COo and 00486 HoO. C-73-4; H = 5-3.
0-1070 „ 0-2860 COo „ 0-0500 H^O. C = 72-9; H = 5-2.
CooHigOiN requires C = 73-l; H = 5-3 per cent.

The results of the physiological experiments, recorded in the
introductory portion of this paper, also afford confirmation of the
fact that )8-/(-dihydroxy-i8-phenylethylaminc had been formed by the
reduction of the w-amino-^^-hydroxyacetojohenone, although the
former couiiDOund could not be isolated in a state of purity.

As previously stated, attempts were made to jDrcpare some of
the above-described compounds by other means. Although the
desired results were not thus attained, these experiments led to
the production of a variety of new compounds, which are described
below.

^j-HydroxyacetojDhenone was reduced by means of sodium
amalgam, both in alkaline and acid sohitions, and also by aluminium
amalgam. The greater part of the product was, in each case, a
viscid oil, but a crystalline solid was also formed, the amount of
the latter being greatest when the neutral reducing agent was
emjDloyed.

Twenty grams of jj-hydroxyacetojDhenone were dissolved in a
large volume of aqueous methyl alcohol, and a quantity of
aluminium amalgam added. The mixture was kept, with occasional
stirring, until the aluminium had disappeared, when the product
was extracted with ether. The material obtained after removing
the solvent was dissolved in ethyl acetate, when 7-5 grams of a
solid, in the form of a crystalline powder, gradually separated.
This product was crystallised from alcohol, when it formed small,
colourless prisms, which melted at 207 — 208°. It was sparingly
soluble in alcohol and in water, and nearly insoluble in ethyl
acetate :

0-1523 gave 0-3908 CO^ and 00914 HoO. 0 = 696; H = 6-7.
CgHj(jOo requires 0 = 69-6; H = 7-2 per cent.
CVHjA „ 0 = 70-1; H = 6-6 „
This substance proved to be the pitiacune, C^^Tli^O^, and not the
desired secondary alcohol, as shown by the molecular weight of its
tetra-acetyl derivative. The latter compound, formed in the usual
way, crystallised from alcohol in colourless leaflets, which melted
at 188— 189°:

01293 gave 03086 COo and 00710 II^O. 0 = 65-1; H = 6-l.
^24^20^8 requires 0 = 652; H=5-9 per cent.

SYNTHESES IN THE EPINEPHRINE SERIES. 2123

0-17G0 in 19-5 of benzene gave \t-0-\2o°. M.W. = 410.
0-1098 „ 22-2 „ naphthalene gave A<-OOSO°. M.W. = 426.
C2.iHooOg requires M.W. = 442.

a-'^-TIydroxyphenylethylamine.

Eight grams of y-hydroxyacetophenoneoxime (m. p. 144 — 145°)
were dissolved in 100 c.c. of aqueous methyl alcohol, and twice the
theoretical amount of 2 per cent, sodium amalgam gradually intro-
duced in small pieces, the mixture being constantly maintained
acid by the frequent addition of acetic acid. When all reaction
had ceased, the liquid was extracted with ether to remove un-
changed oxime, after which it was rendered alkaline by means of
potassium carbonate, and repeatedly extracted with amyl alcohol.
The resulting amyl-alcoholic liquids wei^e extracted with successive
quantities of dilute hydrochloric acid, and the combined acid
liquids concentrated under diminished jDressure. a--^-IIydroxy-
'phenyltiliylamint hydrochloride then separated in stout prisms,
which were purified by recrystallisation from water. This salt is
soluble in alcohol, and insoluble in ethyl acetate; it possesses no
definite melting point, but gradually softens, and darkens at
200 — 280°. Above the latter temperature it yields a sublimate of
ammonium chloride, together with phenol, but it was ascertained
that no 2-'-vinylphenol was formed :

0-1527 gave 0-3086 CO2 and 009G4 HoO. C = 55*1 ; 11 = 7-0.
CgHigONCl requires C = 55-4; Ii = C-9 per cent.

a-'^-If.ydroxyjjhenylethylamine, as obtained from its hydrochloride,
was sparingly soluble in water or alcohol, and insoluble in ether
or chloroform. It formed an amorphous, gum-like mass, which
could not be crystallised.

The dihenzoyl derivative, prepared by the Schotten-Baumann
method, crystallises from dilute alcohol in fine needles, and melts
at 187—188°:

0-1528 gave 0-4280 CO2 and 0-0758 H2O. C = 76-4 ; H = 5-5.
C22Hjg03N requires 0 = 765; 11=5-5 per cent.

a-^-Hydroxy-'ii^-henzoyl'phenylethylamine, HO*C(-H.j'CHMe*NHBz,
was formed on heating the dibenzoyl derivative with 5 per cent,
alcoholic potash. It ci-ystallises from alcohol in large, hexagonal
prisms, melting at 156°:

0-1125 gave 0-3096 COo and 0-0631 HoO. 0 = 75-0; H = 6-2.
C15H15O2N requires 0 = 748; 'h = 6-2 per cent.

Several attempts were made to prepare a-y-dihydroxy-a-phenyl-
ethane by the action of heat on the nitrite of a-p-hydroxyplienyl-
ethylamiue, but the products so obtained were very unstable in the

21-24 TUTIN, CATON, AND HANN :

presence of air, rapidly yielding acetaldehyde and a brown resin.
An experiment was therefore conducted in an atmosphere of carbon
dioxide, and the product immediately acetylated by means of
acetic anhydride. An oil was thus obtained, which distilled at
about 200°/20 mm., and, on analysis, yielded the following result:

0-1522 gave 0-3723 COo and 0-0916 HoO. C = 66-7; H = 6-7.
CJ0HJ2O3 requires C = 66-7; H=G-6 per cent.

It would thus appear that this liquid was a monoacetyl derivative
of a-]i-dih7jdroxy-a-'phenyl ethane.

•p-Vinylanisole Derivatives.

a-Hydroxy-2?-methoxy-o-phenylethane was prepared from anis-
aldehyde by means of the Grignard reaction, and, with the use of
hydrochloric acid, was converted into the chloride. The latter, on
treatment with pp-idine, forms ^j-vinylanisole (Klages, Ber., 1903,
36, 3595).

afi-Dihromo-]i-methoxy-a-'phenyl ethane , MeO'CeH^'CHBr'CHgBr,
was formed by the gradual addition of a cold ethereal solution
of bromine to a solution of ^'-vinylanisole in the same solvent,
cooled in ice. The new compound, which separates from the ether,
was purified by recrystallisation from light petroleum, when it
formed long, prismatic needles, melting at 80 — 81° :

01351 gave 0-1710 AgBr. Br = 53-9.

CgHjoOBro requires Br = 54-4 per cent.

In order to convert the above dibromo-derivative into the bromo-
hydrin, MeO*C6H4'CH(OH)'CH2Br, it was dissolved in acetone
containing 10 per cent, of its weight of water, and the solution kept
at the ordinary temperature (Auwers and Miller, Ber., 1902, 35,
114). It was ascertained, by titrating at intervals aliquot portions
of the mixture, that the reaction proceeded regularly, and was
completed quantitatively at the end of about seven and a-half
hours. On isolating the bromohydrin, however, this compound was
found to be a liquid. Nevertheless, the exact quantitative character
of the change left no doubt regarding the nature of the product.
With the endeavour to prepare an acetyl derivative from the
liquid bromohydrin, the latter was heated with acetyl chloride.
This resulted in the formation of a solid, which crystallised from
light petroleum in needles, melting at 39 — 40°, and proved to be
a-chloro-fi-hromo-T^-methoxy-a-'phenylethane,

MeO-CcHi-CHCl-CHoBr :

0-2223 gave 02939 AgBr + AgCl. Br + Cl = 46-0.

CgHjoOClBr requires Br + Cl = 46-3 per cent.

The bromohydrin was treated with ammonia under a great
variety of conditions, but only small amounts of basic products

SYNTHESES IN THE EPINEPHRINE SERIES. 2125

could be obtained, even wlieu anhydrous, liquid ammonia was
employed. The chief products were, in every case, resinous
materials and volatile, unsaturated oils. Experiments with the
use of potassium phthalimide wei'e equally unsuccessful. The small
yields of basic products which were obtained from the bromohydrin
by means of ammonia were fractionally precijiitated as picrate. In
this manner it was found that at least two compounds were present,
one of which yielded a 'picrate, forming flattened needles, melting
at 215°. The base from the latter crystallised from benzene in
cubes, which melted at 165 — 166°:

0-0520 gave 0-1394 CO. and 0-0348 H.O. C = 73-1 ; H = 7-4.
CgHjiON requires C = 72-5; H = 7-3 per cent.

It would thus ajapear probable that this compound was the base,
MeO-CcH^-CHICH'NHo.

The other 'picrate obtained foi'med stout prisms, melting at 188°,
and the cori'esponding base yielded a benzoyl derivative crystallising
in needles, which fused at 108°, but the amounts were too small
for analysis.

Xd-Aminostyrene.

w-Aminostyrene was prepared from w-nitrobenzaldehyde by
Komppa's method (loc. cit.). It was converted into its hydro-
chloride by passing dry hydrogen chloride into the dry ethereal
solution of the base. The salt thus obtained could not be crystallised
until water was introduced. The latter was then absorbed, with
the evolution of heat, when crystallisation rapidly ensued. The
prodvict so obtained was crystallised from alcohol, and then formed
well-defined jorisms, which melted at 181°:

0-1342, dried at 100°, gave 0-2705 COo and 0-0581 HgO. C = 55-0;

H = 70.
0-3506 gave 0-2870 AgCl. CI = 20-3.
C8H9N,HC1,H20 requires C = 55-3; H = 6-9; CI = 20-3 per cent.

Although the water present in this hydrochloride was not expelled
at 150°, it was, nevertheless, retained as water of crystallisation.
This was shown by the fact that the amorphous, anhydrous hydro-
chloride was again obtained from the regenerated base by treatment
with dry hydrogen chloride.

Benzoylaminostyrene, prepared by the Schotten-Baumann
method, crystallises from alcohol in hexagonal plates, melting at
126 — 127°, and, like the foregoing compound, tenaciously retains
one molecule of water of crystallisation :

0-1377, dried at 130°, gave 0-3755 CO. and 0-0796 H.O. C = 74-4;

H = 6-4.
VOL. xcv. 7 A

2126 BALL: A NEW METHOD FOR THE DETECTION OF

0-099S, dried at 130°, gave 02747 COo and 00586 HoO. C = 75-l;
H = 6-5.
CHjICH-CgH^-NH-CO-CgHs.HjO requires C = 74-7; H = 62 percent.

Komppa {loc. cit.) apparently regarded this compound as being
anhydrous, and stated that it melted at 90 — 91°.

The Wellcome Chemical Kesearch Lahoratories,
London, E.G.

CCXXVIIL— zl New Method for the Detection of
Sodium, Caesium, and Rubidium^.

By Walter Ckaven Ball.

In a former paper (Trans., 1905, 87, 761), the author described
several complex nitrites of bismuth, prepared from the yellow
liquid obtained by the interaction of sodium nitrite and bismuth
nitrate. Among the comjDOunds described were bismuth sodium
ammonium nitrite, Bi(N02)3,2iSrH4NOo,XaN0.2, and bismuth
potassium nitrite, Bi(N02)3,3KN02,H20, both very soluble com-
pounds. On endeavouring to j)repare similar rubidium and caesium
derivatives, it was found that dilute solutions of the nitrates of
these metals produced yellow, crystalline precipitates with the
reagent obtained from sodium nitrite and bismuth nitrate. These
are triple nitrites of bismuth, sodium, and rubidium or caesium, and
their formation serves as a very useful method for detecting these
metals in presence of excess of potassium. The reaction for caesium
is especially delicate.

When, however, rubidium and caesium nitrates were added t<3
the reagent obtained from potassium nitrite and bismuth nitrate,
instead of from sodium nitrite and bismuth nitrate, the result-s
were very different. Rubidium nitrate produced no precipitate,
even when a concentrated solution was used, whilst caesium produced
a precipitate, even when added in dilute solution, yet this pre-
cipitate was very much smaller in amount than that obtained by
adding the same quantity of caesium salt to the bismuth-sodium
nitrite reagent. The precipitate from caesium nitrate and the
bismuth-potassium nitrite reagent was then examined, and was
found to be the triple nitrite of bismuth, sodium, and caesium,
mentioned above, and was quite free from potassium.

It was evident that the potassium nitrite used (Kahlbaum's
purest) contained sodium nitrite, and that the bismuth-potassium

SODIUM, CiESlUM, AND RUBIDIUM. 2127

nitrite reagent, to which caesium nitrate had been added, would
be a delicate reagent for sodium in the presence of much potassium.
It is necessary to use potassium nitrite as free as possible from
sodium, as otherwise much aesium is wasted in precipitating this
when making up the reagent as a test for sodium. Kahlbaum's
purest potassium nitrite was unsuitable for this purpose, as,
although it was free from hydrate and nitrate, yet it contained
about 1 per cent, of sodium nitrite, much more than is contained
in the sticks of nitrite obtained from several other sources.

The exact methods of testing for rubidium, caesium, and sodium
are described below, together with the limits of the tests.

The bismuth-sodium nitrite reagent is best prepared by dissolving
50 grams of pure sodium nitrite in 100 c.c. of water, neutralising
with nitric acid if necessary, and then adding 10 to 20 grams of
powdered bismuth nitrate. The orange-coloured solution of
bismuth-sodium nitrite must then be filtered, and kept in a well-
stopi^ered bottle, as it absorbs oxygen, and becomes turbid when
exposed to the air.

The reagent is hydrolysed by the addition of an excess of water,
with production of a white precipitate; and although this may be
prevented by adding dilute nitric acid at the same time, the delicacy
of the reagent is slightly diminished. It is therefore necessary to
add the solution to be tested to a large excess of the reagent,
acidified with one or two drops of dilute nitric acid. If the solution
to be tested is dilute, the precipitate may take some time to form ;
in this case, the mixture should be kept from contact with the
air in a well-stoppered vessel, in order to avoid any turbidity
caused by oxidation. Should the liquid have become at all turbid,
it may be cleared by the addition of one or two drops cf dilute
nitric acid.

In testing for sodium, as described below, the same precautions
must be observed.

If the salt to be tested is a chloride, its concentration should be
less than 1 per cent., as otherwise bismuth oxy chloride may pre-
cipitate and interfere with the test. In the case of rubidium, it is
best to convert the chloride into the nitrate, which can be done by
evaporating once with strong nitric acid.

Nitrates and sulphates may be used in any concentration.

Detection of Ituhidium.

On addition of 1 c.c. of a 2 per cent, solution of rubidium
nitrate to 4 or 5 c.c. of the bismuth-sodium nitrite reagent, acidified
with a few drops of dilute nitric acid, a bright yellow, crystalline
precipitate forms at once.

7 A 2

2128 BALL: A NEW METHOD FOR THE DETECTION OF

With a 05 per cent, solution, precipitation also occurs quickly,
but a concentration half as great as this only gives a slight
precipitate.

Only the heavy metals and caesium interfere. The test thus
affords an easy method for distinguishing rubidium from potassium,
ammonium, lithium, thallium, etc., which give no similar pre-
cipitates with' the reagent.

The precipitate formed is bright yellow and crystalline. It is
not altered on heating at 100°, but, like all the bismuth nitrite
derivatives, it is decomposed by water and dilute acids. It is a
triple nitrite of bismuth, rubidium, and sodium, and gave, on
analysis, NO2 = 40"40 per cent. As mentioned above, no similar
precipitate is obtained on adding a rvibidium salt to the bismuth-
potassium nitrite reagent, but if to this mixture a solution of
sodium nitrate be added, the same triple nitrite is thrown down.
Prepared in this way, it gave, on analysis, NO2 = 40'74.

Bi(NOo)3,2RbNOo,NaN02 requires NOo = 4"'o-71 per cent.

The substance is thus probably similar in formula to the bismuth
sodium ammonium nitrite described in the former paper, and
mentioned above.

Detection of Caesium.

The same bismuth-sodium nitrite reagent serves also as a much
more delicate test for caesium.

One CO. of a 0"2 per cent, solution of caesium nitrate gives an
immediate yellow, crystalline jDrecipitate with 4 or 5 c.c. of the
reagent.

One c.c. of a 0"02 per cent, solution does not produce an imme-
diate precipitate, but one forms after several hours. A fifth of a
milligram of caesium in 1 c.c. is thus capable of being detected.

The limitations of the test are similar to those in the case of
rubidium. The precipitate is a bright yellow, crystalline powder,
very similar to, but lighter in colour than, the rubidium compound.
It is identical with the compound formed on adding a sodium salt
to a mixture of the bismuth-potassium nitrite reagent and caesium
nitrate, and its composition, apparently rather complex, is con-
sidered in the next section.

Detection of Sodium.

A very delicate reagent for the detection of sodium is obtained
by dissolving 50 grams of potassium nitrite (as free as possible
from sodium) in 100 c.c. of water, neutralising with nitric acid,
and adding 10 grams of powdered bismuth nitrate. To this liquid,
aft«r filtration, a 10 per cent, solution of caesium nitrate is added
until the powdery, yellow precipitate invariably produced (due to
traces of sodium in the potassium nitrite) ceases to be formed

SODIUM, C/ESIUM, AND RUHIDIUM. 2129

on keeping tbo liquid for several hours. Tlie liquid is then
filtei'ed, and the addition of the ccesium continued until the total
amount of coesium salt used is about 2"5 grams. If the potassium
nitrite used should contain much sodium salt, a correspondingly
larger amount of tbo caesium salt must be added. The reagent is
most sensitive when a precipitate of yellow, hexagonal plates (due
to a nitrite of bis)nutli and caesium) forms on furtlier addition of
the caesium salt. The total volume of the reagent prepared in this
way should be about 150 c.c. The proportions may be varied, but
those given seem to give the most satisfactory results. The reagent
must be exposed to the air as little as possible and, if turbid, it must
be filtered before use.

One per cent, solutions of sodium nitrate or sulphate give an
iminediate yellow, crystalline precipitate with the reagent acidified
with a few di'ops of dilute nitric acid. Solutions of half this
strength also produce an almost immediate precipitate.

0"1 c.c. of a O'o per cent, solution of sodium (as nitrate) gave a
considerable precipitate within five minutes with 2 c.c. of the
reagent.

0"! c.c. of a O'l per cent, solution of sodium (as nitrate) gave
with 2 c.c. of the reagent a satisfactory precipitate within thirty
minutes.

0'5 c.c. of a 001 per cent, solution of sodium (as nitrate)
( = 0"00005 gram of sodium) gave with 2 c.c. of the reagent a
precipitate within twelve hours.

O'l c.c. of a O'Ol per cent, solution of sodium (as nitrate)
( = 0'00001 gram of sodium) gave with 2 c.c. of the reagent a
precipitate within twelve hours; this was easily visible to the
naked eye, and, under the microscojDO, was seen to consist of a large
number of characteristic, minute, yellow crystals (octahedra ?).

Thus, about O'Ol milligram of sodium can be easily detected by
this test in the presence of much potassium salt. With the
potassium antimonate test for sodium, it is difficult to obtain a
satisfactory precipitate of acid sodium pyroantimonate when the
concentration of sodium salt is much less than 1 per cent., and
almost all the other metals, including calcium, barium, lithium, and
ammonium interfere with the test.

Most of the heavy metals interfere when testing for sodium with
the bismuth-caesium reagent, as they produce precipitates of double
bismuth nitrites, which are often highly crystalline. Some of
these, particularly the silver compound, have been obtained in a
pure state. Cobalt interferes owing to the production of insoluble
caesium cobaltinitrite. Nickel salts produce a brown, micro-
crystalline precipitate. Zinc, cadmium, magnesium, barium,
ealcium, strontium, lithium, thallium, and potassium do not inter-

2130 DETECTIOX OF SODIUM, CESIUM, AND HURIDIUM.

fere. Ammonium salts do so only in so much as they react with
the nitrous acid of the reagent, giving rise to an evolution of
nitrogen, but it is easy to detect a milligram of sodium salt in
presence of a gram of ammonium nitrate.

The composition of the yellovir precipitate obtained in testing
for sodium was not easily ascertained. The analytical results did
not agree well with the formula Bi(NOo)3,2CsNOo,NaNOo, which
might have been expected from analogy, and the fact that the
ratio between the caesium and sodium was 3 atoms of caesium to
2 of sodium, made the following formula the only possible one :
5Bi(NO.)3,9CsNOo,6NaNOo.

The analytical results given below, which are the means of
several results, are in very good agreement, except as regards the
bismuth, which is too high. It will be noticed that the number of
KOo groups combined with the bismuth and with the sodium and
caesium is the same.

Equivalent of

Bi, KO.j, Cs + Na, tlie mixture

percent. percent, percent. of Cs + Na.

Found 28-4 37-3 36-05 88-9

28-3 36-1

28 4 36-6

— 36-4

Mean = 28 -38 Mean = 36 -6

5Bi(N02):,,9CsNO.,,6XaNOo\ ^-.^ 0R.7 or. a 9C.s + 6Na_„„
requires j- -/ / obi 60b ^ sy

Quantitative Determination of Sodium hy Means of the Reagent.

Preliminary experiments have been made, which indicate that
small quantities of sodium, whether present as nitrate, sulphate, or
chloride, may be accurately estimated by the above method.

(1) Sodium nitrate used = 2 c.c. of a solution containing 0004944
gram of sodium per c.c. = 0"00989 gram Na. Precipitate = 02675
gram. 5Bi(N02)3,9CsN02,6NaN02 contains Na = 3-675 per cent.
Hence Na found = 0'00983 gram.

(2) Sodium chloride used = 2 c.c. of a solution containing 0'003143
gram of sodium per c.c. = 00063 gram Na. Precipitate = 0-1658
gram. Hence Na found = 00061 gram.

(3) Determination of sodium in Kahlbaum's special potassium
nitrite. 0893 gram gave 0'0630 gram precipitate. Hence Na
found = 0-00232 gram, or NaN02 = 0-00695 gram = 0-78 per cent.

The author is at present making a more complete study of the

quantitative estimation of sodium by this method, and hopes to

pi esent a further communication with regard to it.

Chemical LABORAroRT,
Guy's Hospital, S, E.

DERIVATIVES OF ANIIVDROACETOXEBENZIL. 2131

CCXXIX. — Direct Proofs of the Presence of tlie Tlijdroxyl
Groiq) in Derivatives of AnIii/dro(tcetouchc)Lzil.

By Francis William Gray.

Japp and his pupils, by acting on benzil with various ketones in the
presence of alkali hydroxides, have obtained a number of condensation
products, of which the following, together with their derivatives,
have now been further investigated.

Anhydroacetonebenzil (m. p. 148" ; I), its a-methyl (m. p. 118" and
133-5°; II), y8-methyl (m. p. 180°; III), a/3-dimethyl (m. p. 150"; IV),
/?^-dimethyl (m. p. 181°; V), benzylidene (m. p. 213-5° and 232°;
VI), benzylidene-a-methyl (m. p. 225°; VII), and /3-i«opropylidene
(m. p. 205-5° ; VIII) derivatives.

CPh(OH)-CPh CPh(OH).CPh CPh(OH).CPh

CHKco (Jh ^^2<C0 CMe ^^^<C0 CK

(I.) (II.) (III.)

^00 CMe 2^C0 CH

(IV.) (V.)

^UU (JH ^CO CMe

(VI.) (VII.)

r^.r .^ ^CPh(OH)-CPh

(VIII.)

As all these substances contain a hydroxyl group, an acetyl deriv-
ative should be obtainable in every case. I find it possible to acetylate
Nos. V and VI with acetic anhydride containing a few drops of
concentrated sulphuric acid,* and Japp and Knox (Trans., 1905, 87,
675) by the same method acetylated No. VIII. All experiments
made previously by other investigators with the view of acetylating
anhydroacetonebenzil and its derivatives have either left the original
substance unchanged or have led to dehydration products, and I have
had a similar experience except in the cases mentioned above.

For the formation of an acetyl derivative it seems essential that
both hydrogen atoms of the methylene group in anhydroacetone-
benzil should be displaced, but in one case, namely, in benzylidene-
a-methylanhydroacetonebenzil (A^II), where this condition is satisfied,
dehydration occurs ; the] product, however, differs in its nature from
that obtained in the study of the first four substances.

When anhydroacetonebenzil is treated with hot dilute sulphuric

* In the remainder of the introduction this reagent will be referred to as "aceti c
anhydride and sulphuric acid."

2\:ll C.KAV : rKESENCE OF THE IIYDKOXYL GUOUP IN

.acid (Japp and l^mrton, Trans., 1887, 51, 425), or with acetic
anhydride and sodium acetate (Japp and Lander, Trang., 1897, 71,
130), it yields the dehydration product, but with acetic anhydride
it remains unchanged (Japp and Miller, Trans., 1885, 47, 33). The
behaviour of the dehydration product on heating led Japp and Burton
to represent the dehydration thus :

The behaviour of the dehydration derivative on heating a little
above its melting point agrees almost exactly with the equation :

Japp and Meldrum (Trans., 1901, 79, 1031), by boiling a-methyl-
anhydroacetonebenzil with dilute sulphuric acid, or with glacial acetic
acid, obtained a dehydration jiroduct, CggUggO^j melting and decom-
posing at 230°. The reaction is represented by the equation :

2^18^16^2 ~ 21120 = C3eH2s02,
and is analogous to the dehydration of anhydroacetonebenzil. Japp
and Meldrum obtained the same dehydration pi'oduct from /8-methyl-
anhydroacetonebenzil by the action of anhydrous formic acid,
whereas desylenemethyl ethyl ketone, COPh-OPhlCH'COEt, was
formed by the action of glacial acetic acid.

I have prepared these dehydration products by other methods, and
have obtained also the dehydration products of a^-dimethylanhydro-
acetonebenzil and benzylidene-a-methylanhydroacetonebenzil, the
ethyl ethex's of a-methylanhydroacetonebenzil and benzylidene-a-
methylanhydroacetonebenzil, and the acetyl derivatives of (Sft-di-
methylanhydroacetonebenzil and benzylideneanhydroacetonebenzil.

By boiling anhydroacetonebenzil with absolute alcohol and sulphuric
acid, or by treating it with cold acetic anhydride and sulphuric acid,
the dehydration product is obtained ; cold glacial acetic acid, con-
taining a few drops of concentrated sulphuric acid, leaves the substance
unchanged. Acetic anhydride and sulphuric acid effect dehydration
of a- and ^-methylanhydroacetonebenzil. On boiling a-methyl-
anhydroacetonebenzil with efchyl alcohol and sulphuric acid, the ethyl
ether is obtained, and when methyl alcohol is used^in this reaction,
the methyl ether is formed. ^-Methylanhydroacetonebenzil is not
attacked when boiled with ethyl alcohol and sulphuric acid, or when
treated with cold glacial acetic acid containing a few drops of
concentrated sulphuric acid.

Cold acetic anhydride and sulphuric acid, and also cold glacial
acetic acid containing a few drops of concentrated sulphuric acid,
effect dehydi-ation in a^-dimethylanhydroacetonebenzil. The reaqtion
may be represented by the equation :

2Ci,H,802-2H20 = C38ll3202.

DERIVATIVES OF ANnVDROACETONEHENZIL. 2133

Tbo product melts at 181 — 182°, and evolves carbon monoxide.
The action of beat may, on the analogy of the behaviour of the
dehydration product of anhydroacetonebenzil, be represented as

C3sn320„ = C37H.,,,0 + CO.
Whilst there are indications tiiat this analogy holds good, yet neither
for the dehydration product of a-methylanhydroacetonebenzil nor for
that of a/?-diinethylanhydroacetonobenzil have I obtained exact
quantitative results, such as were found in the case of the anhydro-
acetonebenzil dehydration product.

The dehydi-ation product of -benzylidene-a-niethylanhydroacetone-
benzil is prepared by the action of cold acetic anhydride and sulphuric
acid ; it melts at 245°, no evolution of gas being observed.

In this case possibly one molecule of the original substance yields
one molecule of the dehydration product, thus :

CHP.:c<-Mo.n;CPH _„^, ^ chp.c^-V-^.

the double linking in the five-carbon ring changing its position,
whereas in the case of the four other dehydration products two
molecules of the original substance give one molecule of the dehydra-
tion product.

By boiling benzylidene-a-methylanhydroacetonebenzil with absolute
ethyl alcohol and concentrated sulphuric acid, the ethyl ether is
produced.

Thus, whilst the direct evidence of acetylation has not been forth-
coming as a proof of the presence of the hydroxyl group in Nos. I, II,
III, IV, and VII of the above list, yet in the case of a-methyl- and
benzylidene-a-methyl-anhydroacetonebenzil I have succeeded in pre-
paring ethyl ethers by the action of boiling absolute alcohol and
sulphuric acid.

It is to be noted that, when the ethyl ether is obtained by this
method, the original substance contains a methyl group in the
a-position. The same treatment gives in the case of anhydroacetone-
benzil the dehydration derivative, and leaves the benzylidene-^-
methyl and ^^-dimethyl derivatives unchanged. The action on
a^-dimethyl- and /3-isopropylidene-anhydroacetonebenzil has not been
tried.

In this connexion it may be remarked that the same treatment
yields an ethyl derivative in the case of a-methylanhydroacetone-
dibenzil (Japp and Meldrum, loc. cit., p. 1035). This agrees with the
above rule, to which there is no exception.

The ethyl ether of a-methylanhydroacetonebenzil (m. p. 110°) yields
on i-eduction with concentrated hydriodic acid, 3 : 4-diphenyl-
2-methyl-A^-c?/ c^opentenone, already obtained by Japp and Meldrum

SL'U GRAY: PHESE?:CE OF THE HYDROXYL GROUP IN

(he. cit.) by the reduction of a-methylanhydroacetonebenzil ; again
the ethyl ether of a-niethylanhydroacetonebenzil yields a-methyl-
anhydroacetonebenzil on oxidation with hydrogen peroxide, and a
benzylidene derivative when treated with benzaldehyde and alcoholic
potash. This derivative is also produced by the action of boiling abso-
lute alcohol, containing a few drops of concentrated sulphuric acid, on
benzylidene-a-methylanhydroacetonebenzil, as was to be expected.

Its formation from the ethyl ether of a methylanhydroacetonebenzil
is to be taken as a proof of the presence of the group CH^'CO in the
latter. Wallach and others have shown that the condensation of
aldehydes with cyclic ketones takes place only when the latter contain
a methylene group directly attached to carbonyl.

Experimental.
Dehydration Product of a^Dimethylanhydroacetonehenzil, CggHgjOg.

Five grams of ayS-dimethylanhydroacetonebenzil, 20 c.c. of acetic
anhydride, and 10 drops of concentrated sulphuric acid were mixed
at the ordinary temperature. The liquid became green, and crystals
quickly separated out (3'8 grams). On recrystallisation from hot
alcohol, long, rectangular pi'isms were obtained, melting and decom-
posing at 181—182° :

0-1495 gave 0-4807 CO., and 00832 H^O. 0 = 87-66 ; H = 6-18.*
CggHgjO, requires 0 = 87-69 ; H = 6-15 per cent.

Analogous dehydration products have already been prepared by
other experimenters, and new methods of preparing these substances
have been discovered in the present research, as explained above.

Of these, the simplest is that in which acetic anhydride and
sulphuric acid are employed, the preparation being analogous to that
just described, except that in the other cases the product is not
obtained in so short a time. A very minute proportion of concentrated
sulphuric acid is effective.

4:-Ethoxy-3 : 4.-diphenyl -2 -methyl- /ii^-cyclopentenone,
,CPh(OEt)-CPh
^00 CMe"

2\r<n r

A mixture of 3 grams of a-methylanhydroacetonebenzil, 60 c.c. of
absolute ethyl alcohol, and 3 drops of concentrated sulphuric acid was
boiled for three hours. Water precipitated a solid, which crystal-

At least two nnalyses were made in the great majority of cases in this and the
following paper, but only oue analysis is given here as elsewhere in order to save
space.

DERIVATIVES OF ANTIVDROACETONEBEXZIL. 2135

Hsed from its hot alcoholic solution in lustrous lauiiiiii' melting
at 110°:

. 0-1504 gave 0-4537 CO, and 0 0953 H^O. C = 82-27 ; H = 7-05.
CoolI.oO, requiVes C = 82-19 ; H = 685 per cent.

Action of Ut/drogen Peroxide. — When a mixture of 3 grams of
this substance, with sufficient glacial acid to dissolve it, and 200 c.c.
of hydrogen peroxide (6 per cent.) was heated on the water-bath for
four hours, a-methylanhydroacetonebenzil was obtained in good yield.

Action of Ilydriodic Acid. — A mixture of 2 grams of 4-ethoxy-3 : 4-
diphenyl-2-methyl-A--fv/c^opentenone and 20 grams of concentrated
hydriodic acid (1) TOG) w;is boiled for four minutes. After adding
water, the precipitate was extracted with ether, the ethereal solution
shaken with sulphurous acid and then with sodium carbonate solu-
tion, and dried. Ou spontaneous evaporation, pale yellow, six-sided,
oblique, flat prisms or plates separated, which, when recrystallised
from light petroleum, melted at 77 — 78°, and were proved to consist of
3 : 4-diphenyl-2-methyl-A^-c?/c/opentenone.

4:-Methox7/-3 : 4 -diphen7/l-2-methyI-dk'^-cyc\opentenone,
CPh(OMe)-CPh
^^2<co IJMe-

The preparation of this substance is similar to that of the corre-
sponding ethyl ether. It crystallised from alcohol in small, rectangular
plates melting at 69° •

0-1650 gave 0-4959 CO^ and 0-0983 B.fi. C = 81-96; H = e-62.
CjgH^^Oo requires C = 8201 ; H = 6-47 per cent.

i-Ethoxy-Z : 4:-dij)henyl-5-benzylidene-2-methyl-A^-cyc\opentenone,

,CPh(OEt)-CPh
-CO CMe"

CHPh:c<':; J ' u

This svibstance was piepared by two methods :

( 1 ) Two grams of 4-ethoxy-3 : 4-diphenyl-2-methyl-A2-cyc/opentenoTie
were dissolved in alcoholic potash (3 grams of potas.sium hydroxide in
50 grams of absolute alcohol), and 1 gram of benzaldehyde was added,
the mixture being kept at the ordinary temperature for twenty-four
hours. The crystals which separated, after recrystallisation from hot
alcohol, contained alcohol of crystallisation, and melted at 149-5°.
When crystallised from light petroleum, they separated in long, six-
or eight-sided plates, melting at 150°. The total yield was about
2 grams. After being kept overnight in a vacuum over sulphuric
acid, the subs tance crystallised from alcohol was analysed :

2136 GRAY : PRESENCE OF THE HYDROXYL GROUP IN

0-1 652 gave 0-5025 COo and 0-1004 H2O. C = 82-94 ; H = 6-75.

0-2439, heated at 120°, "lost 0-01 10. EtOH = 4-59.
2Co;H2402,EtOH requires 0 = 83-37; H = 6-70; EtOH = 4-57 per cent.

After being kept in a vacuum over sulphuric acid for several
days :

0-1560 gave 0-4831 CO^ and 0-0928 H2O. 0 = 84-45 ; H = 6-61.
CoyHo^Og requires C = 85-20 ; H = 6-31 per cent.

The substance had therefore not completely parted with its alcohol.
A specimen freed from its alcohol by heating has not yet been
analysed. It seems likely, however, that the above formula would
be confirmed.

(2) A mixture of benzylidene-a-methylanhydroacetonebenzil, ethyl
alcohol, and concentrated sulphuric acid was boiled for several hours,
and the product recrystallised from alcohol. The first crop^of crystals
consisted of unchanged substance. The crystals from the mother
liquor were treated with three successive portions of boiling light
petroleum, when the second and third portions gave unchanged sub-
stance, but from the first extract there were deposited pale yellow, six-
or eight-sided plates and a small amount of minute, white crystals.
These, being ■ specifically lighter, were separated from the heavier,
yellow crystals by means of hot light petroleum. The latter crystals,
of which the yield was poor, were identified by the mixed melting-
point test as 4-ethoxy-3 : 4-diphenyl-5-benzylidene-2-methyl-A2-c?/c^o-
pentenone.

3 : 4:-Diphenyl-5-benzylide')ie-2-7neth2/lene-A^-cjc\opentenone,

This substance was prepared as follows :

Ten grams of benzylidene-a-methylanhydroacetonebenzil, 60 gramss
of acetic anhydride, and 6 drops of concentrated sulphuric acid were
kept at the ordinary temperature for four days, and the red solid
which had precipitated was washed with alcohol. After crystallisa-
tion from benzene and light petroleum, and then from benzene and
alcohol, 2 grams of a yellow substance, melting at 245°, were
obtained. This was insoluble in alcohol, and very soluble in
benzene :

0-1454 gave 0-4746 COg and 0-0710 HgO. C = 89-00 ; H = 5-42.
CgsHjgO requires C = 89-8 ; H = 5-4 per cent.

DERIVATIVES OF ANHYDROACETONEBENZTL. 2L'37

4:-Aceioxi/-3 : 4:-dipheni/l-5-benzi/l{dene-j\'^-cyc\opentenone,
CHPh.C<^^ Kjj .

Sixteen grams of benzylideneanhydroacetonebenzil (m. p. 232°),
128 c.c. of acetic anhydride, and IG drops of concentrated sulphuric
acid were mixed, and kept at the ordinary temperature for twenty-
four hours. More than this amount of sulphuric acid was found to
blacken the mixture. The solid which precipitated was separated by
filtration, washed with cold alcohol, and extracted with successive
portions of boiling alcohol, from which it crystallised in very slender,
yellow needles, melting at 175°. The yield was 8 grams. The same
substance was obtained in a similar experiment performed with the
modification of benzylideneanhydroacetonebenzil • melting at 213'5°
(see following paper) :

0-1354 gave 0-4078 COg and 0-0659 H,0. C - 82-14 ; H = 5-40.
^20^20^3 requires 0 = 82-10; H = 5-26 per cent.

4:'Aceioxy-3 : 4:-diphenyl-5 : S-dlmeihyl- A" -cy clopentenone,
^,^ .CPh(OAc)-CPh

As a large amount of this product was required for experiments
on its hydrolysis (see following paper), the method of employing a
mixture of acetic anhydride and sulphuric acid at the ordinary
temperature was varied by reducing the quantity of anhydride and
acid, whereby the yield of acetyl derivative was improved : 72 grams
of jS^-dimethylanhydroacetonebenzil, 120 grams of acetic anhydride,
and 15 drops of sulphuric acid were heated on a sand-bath until all
the solid had dissolved ; on cooling, large, stout, oblique, four-sided
plates separated, which, when recrystallised from alcohol, melted at
137°. The yield was 77 grams :

0-1448 gave 0-4157 CO^ and 0-0843 H.O. C = 78-30 ; H - 6-47.
C2XH20O3 requires C = 78-75 ; H = 6-25 per cent.

A negative result was obtained with glacial acetic acid and
concentrated sulphiaric acid.

Chemical Department.

University of Acerdeen.

2138 GRAY : ISOMEKIDES OF ANHYDROACETONEBENZIL

CCXXX. — I.soinc rides of Anhydroacetonehenzil and its

Derivatives.

By Fbancis William Gkay.

By treating the acetyl derivatives of benzylideneanhydroacetonebenzil
and ^yS-dimethylanhydroacetonebenzil (see preceding paper) with
alcoholic potash, substances were obtained isomeric with the parent
compounds, but differing from these in physical and chemical behaviour.
The products of deacetylation are soluble in aqueous potassium
hydroxide, and are precipitated from the solution with carbon dioxide,
thus behaving like monohydric pheuols ; they also give the ferric
chloride colour test characteristic of these compounds.

Japp and Knox treated the acetyl derivative of /3-isopropylidene-
anhydroacetonebenzil in the same way with alcoholic potash. The
resulting substance was not isolated in the pure state, but it showed no
sign of dissolving in aqueous potassium hydroxide, and I found that it
did not give a coloration with ferric chloride, so that the deacetylation
in this case does not seem to proceed in the same way as do the
deacetylations already mentioned.

In the two cases mentioned above, where deacetylation leads to
new phenolic compounds, the constitution of the latter has been
investigated, and it ha^ been found that benzylideneanhydroacetone-
benzil (3 : •l-diphenyl-5-benzylideue-A'--c^c/openten-l-oue-'i-ol) yields
3 : 4:-d{phenyl-5-benzi/lidene-A^-cjc\op3nten-l-07ie-'2-ol,

and ^yS-dimethylanhydroacetonebenzil (3 : 4-diphenyl-5 : S-dimethyl-A^-
c?/cZopenten-l-one-4-ol) gives 3 : A-dipheni/l-5 : 5- dimethyl- A.^-cyclopenten.
l-one-'2-ol,

^,^ CPh(OH)-CPh ^,,, .CPh(OAc)-CPh

CMeo<^ II — > CMeo<^ ^ 1 1 — >

,CHPh-CPh

'CO C-OH'

On deacetylation of their acetyl derivatives (prepared by means of
acetic anhydride and sulphuric acid), the 2-hydroxy-compounds are
regenerated.

When the results obtained with boiling acetic anhydride alone as an
acetylating agent are considered, there are introduced in the case of
the first substance, possibilitie.s which make the changes more
complicated than the above. This will be ex^jlained later.

^Me,<,,^__ii

AND ITS DERIVATIVES. 2139

Thus, in tho present research, 2-hydroxy-compounds have been
obtained isomeric with two of the eight 4-hydroxy-compounds men-
tioned in the list given at the beginning of the preceding paper. In
the case of one of the three 4-hydroxy-compounds which give acetyl
derivatives, hydrolysis does not yield a 2 hydroxy-isomeride, so that in
the case of the five substances from which acetyl derivatives have not
been prepared, the method of the present research might not lead to
2-hydroxy-isomerides even if acetyl derivatives or other esters should
be prepared, and even if tlie 2-position in the five-carbon ring is
occupied by the hydrogen atom. But other methods may be available.
In fact, the 2-hydroxy-isomeride of anhydi-oacetonebenzil itself has
been prepared by Vorliinder and Schroedter [Ber., 1903, 36, 1490;
compare also Vorliinder and von Liebig, Ber., 1904, 37, 1133; von
Liebig, Diss., Halle, 1904 ; and Metge, Diss., Halle, 1904).

Vorliinder and Schroedter, by acting with acetic anhydride and a
large quantity of concentrated sulphuric acid on dibenzylideneacetone,
obtained a substance, Cj-Hj302Ac(H*S03H), from which, on hydrolysis,
was obtained a compound, C^-H^^Oo, to which they assigned the
constitution :

The constitution of the intermediate compound, Cj-Hj^02Ac(H 'SO.^H)

has not been ascertained, but the fact that the final reduction product

of the 2-hydroxy-compound (namely, the hydrocarbon, Cj-H^g or

CHPh'CH.,^ /~,TT \'i-ir

' ^ '^\Ji±.^) is obtained from the sulphurous acid compound,

C-tLi:n'C'H2

from the 2-hydroxy-compound, and from the intermediate reduction

product of the 2-hydroxy-compound (namely, from the ketone, U]-HjgO,

CHPh-CH,. ^,^ CHPh-CH.,^ ^^, ^ , ^. .,,',.

('.fjpij__QQ>C'H2, or ^i^pij.qjj'^ ^ ^ reduction with hydriodic

acid, is given as evidence in support of the theory that the five-
carbon ring is present in the intermediate compound,

Ci-Hi,02A.c(H-S0yFI),
and against the theory that the closing of the five-carbon ring
takes place on hydrolysis. It cannot be maintained, however, that
the position in the ring occupied by the acetoxy-group is the same
as that occupied by the hydroxyl group of the 2-hydroxy-compound
obtained on hydrolysis. Further, in the light of the results here
described, it seems possible that the first hydroxyl group may occupy
the 4-position. Thus, the method of preparing the acetyl derivative
of the 2-hydroxy-compouiid, and then treating it with sodium
hydrogen sulphite, the method adopted by Metge in attempting
unsuccessfully to synthesise the compound, Cjj.Hj302Ac(H*S03H), even

2140 GRAY : ISOMERIDES OF ANHYDROACETONEBENZIL

if it gave a substance of the desired percentage composition, might
lead to one of different constitution.

In defence of the constitution given above for the substance
Cn^Hj.Og, VorUinder quotes the following experimental results :

Boiling with concentrated aqueous potassium hydroxide gave
deosybenzoin and monomethylstilbene, CgH^'CMelCH-CgHg, showing
that the following change had occurred :

CHPhlCH^^ CF^^^^^no

CHPhlCH^^^ -^ CPh-C^^'

I /\

the two ^-carbon atoms of dibenzylideneacetone uniting, and the five-
carbon ring being formed.

Oxidation with chromic acid or with permanganate gave benzil and
desylacetic acid, CHPhBz-CH./CO.^H.

This, -and the fact that a benzylidene derivative was formed by
condensation with benzaldehyde, agree with the structure :

cph - a,

CHPh-CH^-^^'^*

As far as these results are concerned, the constitution might be
CHPh-CO CPh:C(OH)

CHPh-CH>^^ ^"^ CHPh-CH>^^-

No sign of a quinoxaline derivative has been observed on treatment
with o-phenylenediamine, so that the former formula is improbable.
The latter is therefore chosen ; and this is confirmed by the acid
properties of the substance, and the formation of acetyl and benzoyl
derivatives.

The benzylidene derivative of Vorliinder's 2-hydroxy-compound,
referred to above, is of considerable importance in connexion with the
present research. Before knowing that von Liebig had prepared this
derivative, it occurred to the author that it might be of interest to
prepare this substance from Vorliinder's 2-hydroxy-compound and to
compare it with the 2-hydroxy-isomeride of benzylideneanhydroacetone-
benzil, obtained by the method described in the present paper. It was
to be expected that these two benzylidene compounds would be identical.

The benzylidene-2-hydroxy-compound prepared, for comparison, by
Vorlander's method had the correct percentage composition, C^^HigO^,
and agreed with the description given by von Liebig, crystallising in
fine, yellow needles (m. p. 223°).

The benzylidene-2-hydroxy-compound obtained from benzylidene-
anhydroacetonebenzil had the same appearance, but melted at 216°.

These two compounds are chemical isomerides. This is not a case
of dimorphism, but, perhaps, of malooid and fumaroid isomerism.

AND ITS DERIVATIVES. 2141

The two substances give the same dark brown coloration with ferric
chloride, and they yield, on acetylation in the cold with acetic
anhydride and sulphuric acid, the same acetyl derivative (yellow
needles, m. p, 175 — 176°), from which, on deacetylation, the 2-hydroxy-
compound, melting at 216°, is obtained. It should bo noted, however,
that in this acetylation of the 2-hydroxy compound melting at 216°, a
very small quantity of another substance (acetyl derivative) is
obtained, crystallising in almost colourless plates, melting at 148 — 152°
(softening at 148°).

Again, these 2-hydroxy-compound3, when boiled with acetic
anhydride alone, both give the same acetyl derivative, crystallising in
almost colourless plates, melting at 148 — 152° (according to von
Liebig, almost colourless, oblique prisms, m. p. 148 — 149°), which was
shown by the mixed melting-point test to be the same as the substance
obtained in small quantity by acetylation with acetic anhydride and
sulphuric acid. The acetyl derivative melting at =148 — 152° yields,
on deacetylation, the 2-hydroxy-compound melting at 223°.

The direct transformation of the more soluble and less stable
2-hydroxy-compound, melting at 216°, into the less soluble and more
stable 2-hydroxy-compound, melting at 223°, can be effected by means
of a concentrated solution of hydrogen chloride in absolute alcohol.
The 2-hydroxy-c mpounds may have the configurations :

H Ph

-.^^CHPh-CPh , -.^.^CHPh-CPh

OlC<' II and C.C< N

., XO C-OH ,v CO C-OH

Ph 11

No experimental results, however, are available for settling which
of these configurations is to be assigned to the more stable substance,
nor are there even, so far as the author is aware, any analogies which
might serve as a guide in arriving at a conclusion.

Experiments carried out with the 2-hydroxy-isomeride of ^/3-di-
methylanhydroacetonebenzil, CjgHjgO^ (m. p. 155 — 156°), lead to a
constitution similar to that given by Vorliinder to the 2-hydroxy-
isomeride of anhydroacetonebenzil :

(1) Oximation experiments were successful in the case of
)8/3-dimethylanhydroacetonebenzil and its acetyl derivative, but failed
in the case of the 2-hydroxy-compound, with which hydroxylamine
seems to react, giving two substances, of which the amounts obtained
were too small for analysis. A phenylhydrazone, however, is obtained
with the 2-hydroxy-compound. These results show the presence
of one carbonyl group in each of the substances examined.

(2) A methyl ether, Ci,,Hi70(0Me) (m. p. 88-5°), and an acetyl
derivative, C\cjH^70(0Ac) (m. p. 92"5°), were obtained.

(3) Reduction of the 2-hydroxy-compound with bydriodic acid
VOL. XCV. 7 B

2142 okay: isomerides of anhydroacetoneijexzil

yields a neutral substance, CjciHgoO (m. p, 153°), which reacts
with hydroxylamine ; to this substance the formula
^_ X'HPh-CHPh

may be assigned.

^;8-Diniethylanhydroacetonebenzil should, on reduction, yield the
same product, but no definite substance could be itiolated from this
reaction.

(4) Oxidation with permanganate or with hydrogen peroxide gives
a-desylisobutyric acid, COPh-CHPh-OMea-COgH.

(5) Oxidation with potassium hypobromite gives an acid, Cj^Ho^Oj
(m. p. 197°), to which the following constitution ha's been assigned :

^,, ,CHPh-CPh'COoII „ ^
CMe,<^^ ^ - ,H20.

Tliis structure agrees with the following properties of this acid :
(a) it loses a molecule of water at 113°. (b) It is inert towards
acetylating agents, (c) It is inert towards bydiiodic acid unless the
mixture is heated with red phosphorus in a sealed tube at 150°, when it
yields /3y-diphenyl-aa-dimethylbutyricacid,CH2Ph-CHPh-CMe2-COoH,
and the lactone of y-hydroxy-ySy-diphenyl-aa-dimethylbutyric acid,
^.,^ /CHPh-CHPh

(d) It is a monobasic acid, as shown by the analysis of its silver
salt and by titration with standard alkali.

(e) It is a lactone of the acid CO,H-CPh(OH)-CHPh-CMe2-C02H,
the disodium salt of which has been prepared fi'om the acid Cj^HgoO^,
the lactone ring being broken in the process.

(6) The experiments with potassium hydroxide were of considerable
importance in the case of Vorliinder's 2-hydroxy-compound, showing,
as they did, that the two /8-carbon atoms of dibenzylideneacetone had
united, the five-carbonsring being formed. Now, although the same
experiment does not throw the same light on the constitution of the
2-hydroxy-isomeride of /3^-dimethylanhydioacetonebenzil (the benzil
refcidue being already present in /?/3-dimethylanhydroacetonebenzil),
it seemed likely that the product obtained would be isopropylstilbene
on the analogy of Vorliinder's experiment which gives monomethyl-
stilbene, thus :

Ch4^!!:§!o''h -- CMeP.:CHPU

GMo,<^^^^'m^^^ -^ CHMe.,-CPh:CHPh.
The pioduct, however, was stilbene itself. This result is not to be

AVD ITS DERIVATIVES. 2143

regarded as inconsistent with the constitution indicated by tlie other
experiments described in this paper.

The oxidation experiments and the empirical formula show that
the structure of the 2-hydroxy-compound mu>t be

,„^ .CHPh-CPh-
CMe,<c 6< •

Acetylation and methylation experiments show that the substance
contains a hydroxy! group, and the action of phenyl hydrazine pioves
the presence of a carbonyl group ; consequently, the only way of
accounting for the&e is by the expression

^^^ .CHPh-CPh ^

^^CO C-OH

This formula is consistent, not only with the chemical properties of
the substance itself, but also with the results obtained by Vorliinder
in his experiments on the 2-hydroxy-isomeride of anhydroacetone-
benzil.

Experimental.

Benzylideneanhydroacetonehenzil.

On repeating Japp and Findlay's method of preparation of this
substance (Trans., 1899, 75, 1023), there was found in the first hot
alcoholic extract of the crude product (which Japp and Findlay
assumed to give unchanged anhydroacetonebenzil) a substance crystal-
lising in prisms, melting at 213'5°, Subsequent extracts yielded six-
sided plates (m. p. 232"^).

The substance melting at 213'5° was found to be i&omeric with
benzylideneanhydroacetonebenzil :

01472 gave 0-4582 CO.^ and 0-0740 H.p. C = 84-9G ; H = 5-59.
^'24^18^2 I'equires C = 8520 ; H = 5-32 per cent.

The substance melting at 232° had the appearance and melting
point hitlierto assigned to benzylideneanhydroacetonebenzil.

When treated with acetic anhjdride and concentrated sulphuric
acid, these two substances give the ;^ame acetyl derivative, melting
at 175° (see preceding paper). They are different forms of benzyl-
ideneanhydroacetonebenzil, perhaps maleoid and fumaroid isomerides.

Japp and Findlay found (Trans., 1899, 75, 1018) that acetic
anhydride alone did not act on benzylideneanhydroacetonebei\zil
(m. p. 232°) even when the temperature was raised to 150°; this is of

* The substance is not only an enol, but also a ketone at the same time, and
"Vorliinder uses the term "keto-enol" in referring to a compound of this kind.
This name has, however, been rrjected by the present author, because in wliat is
usually called "keto-euolic isonierihni" the substance is an enol and a ketone
alternately.

7 B 2

2144 GRAY: ISOMERIDES OF ANIIYDROACETONEBENZIL

interest in connexion with the behaviour of the two 2-hydroxy-
isomerides.

The yield of the substance melting at 213'5° was small, whilst about
24 grams of the substance melting at 232° were obtained from
20 grams of anhydroacetonebenzil.

An attempt to transform from the one substance to the other was
not successful. There are indications, however, that the substance
melting at 213'5° can be converted into the substance melting at 232°
by means of an alcoholic solution of hydrogen chloride.

3 :4:-Diphenyl-5-benzylidene-A'^-cyc\openten-\-one-2-ol (m. p. 21G°),

CHPh:c<^«P^-fi^^

^CO C'OH •

Eight grams of the acetyl derivative (m. p. 175°) of benzylidene-
anhydroacetonebeuzil were mixed with an excess of a 5 per cent,
alcoholic solution of potassium hydroxide. The acetyl derivative
dissolved, giving a red solution, and much heat was developed. This
solution was kept at the ordinary temperature for a few days. If
water is added to the red liquid, a brilliant red solid is obtained, but
if the red liquid is acidified with hydrochloric acid, the red colour
disappears and a yellow precipitate is formed. This dissolves in
aqueous potassium hydroxide, from which it is reprecipitated by
carbon dioxide. Its alcoholic solution gives with a drop of ferric
chloride solution a dark brown coloration.

The substance crystallises from alcohol in small cluster's of fine
needles melting at 216° :

0-1646 gave 0-5157 CO., and 0-0794 HgO. 0 = 85-45; H = 5-3G.
Cg^HjgOg requires C = 85'20; H = 5-32 per cent.

3 '.^:-Diphenyl-5'henzylidene-^^-(fyc\openien-\-one-2-ol (m. p. 223°).

3 :4Diphenyl-A2-c?/c?openten-l-one-2-ol was prepared by the method
described by Yorlander {loc. cit.) ; the following points require special
attention.

During the gradual addition of sulphuric acid, the temperature
should not be allowed to fall lower than 25 — 30°, the temperature
recommended by Yorltinder.

After the addition of all the acid, too long a time should not elapse
before the mixture is worked up. The whole preparation should
be carried out in one day. Further, in heating with alkali to effect
hydrolysis of the intermediate sulphurous acid compound, sufiicient
time should be given for the reaction to be completed, otherwise,
on acidifying, there will be obtained a product difficult to purify.

AND ITS DERIVATIVES. 2145

One gram of 3 : 4-diphenyl-A--c?yc^openten-l-one-2-ol was dissolved in
30 c.c. of absolute alcohol containing 1 gram of potassium hydroxide,
and 0*5 gram of benzaldehyde was added. This mixture was kept at
the ordinary temperature for four days. On adding it to a large bulk
of water, a clear solution was obtained, and, on passing carbon dioxide
through it, an orange-coloured precipitate was obtained, which crystal-
lised from hot alcohol in clustei's of light yellow needles melting at
220°. Von Liebig gives the melting point 223 — 224°, and by
employing another method of preparing this substance, the present
author obtained it with the melting point 223°. The product is
therefore probably identical with von Liebig's compound, although
the melting points differ slightly. The yield of pui'e substance
I'ecrystallised from alcohol was 0'55 gram :

0-1464 gave 0-4560 CO2 and 0-07 H2O. 0 = 84-94; H = 5-31.
C24H18O2 requires 0 = 85-20; H = 5-32 per cent.

This substance is also obtained when the 2-hydroxy-compound
melting at 216° is added to enough of a concentrated solution of
hydrogen chloride in absolute alcohol to give a clear solution ; it
crystallises from this solution in a very pure state, and in large
amount.

2-Acetoxi/-3 : 4:diphenyl-5-benzylidene-^^-cyclopentenone
(n>.p.l75-176»),CHPh:c4^5.':§:;\^.

When the 2-hydroxy-compound melting at 216° was treated with
acetic anhydride and a few di-ops of sulphuric acid at the ordinary
temperature, two products were obtained, the chief of which crystallised
from alcohol in very fine needles melting at 175 — 176°, and retaining
their form on recrystallisation. From the alcoholic mother liquor
there separated a very small quantity of almost colourless, rhombic
plates, the melting point of which was rather indefinite. The substance
softened at about 148 — 149°, and melted to a clear liquid a few degrees
higher.

Analysis of the compound melting at 175 — 176° :

0-0936 gave 0-2795 CO2 and 0-0468 H^O. 0 = 81 -43 ; H = 5-55.
O26H20O. requires 0 = 82-10 ; H = 5-26 per cent.

A mixture of the acetyl derivative (m. p. 175°) of benzylidene-
anhydroacetonebenzil and the acetyl derivative (m. p. 175 — 176°)
of the 2-hydroxy-compound melted at 155°, showing that these sub-
stances, although they have the same composition and melting point,
are not identical.

This substance (m. p. 175 — 176°) may also be prepared by the action

'2146 GRAY: ISOMERIDES OF ANHYDROACETONEBENZIL

of acetic anhydride and sulphuric acid at the ordinary temperature on
the 2-hydroxy-compound melting at 223°.

The hydrolysis of this ester may be effected by means of 5 per cent,
alcoholic potash, the method being similar to that employed in the
preparation of 3 : 4-diphenyl-5-benzylidene-A"-ci/c/openten-l-one-2-ol
(p. 2144); the 2-hydroxy-compound melting at 216° is obtained.

2-Acetoxy-3 : i-dip7ieni/l-6-benzylidene-A^-cyv\oj)ente7ione
(m. p. 148—152°).

A mixture of 12 grams of acetic anhydride and 0-6 gram of the
2-hydroxy-componnd melting at 216° was boiled for one and a-half
hours. The product obtained on adding water crystallised from
benzene in almost colourless, rhombic plates, which soften at 148 — 149°
and melt to a clear liquid at about 152°. Liebig, by the action of
boiling acetic anhydride on the 2-hydroxy-compound melting at 223°,
obtained an acetyl derivative which he describes as consisting of
almost colourless, oblique prisms melting at 148—149°. These acetyl
derivatives are doubtless the same.

On hydrolysis by means of 5 per cent, alcoholic potash, the
2-bydroxy-compound melting at 223° is obtained.

From the hydrolysis experiments, therefore, the acetyl derivative
melting at 148 — 152° corresponds with the 2-hydroxy-compound melt-
ing at 223°, and the acetyl derivative melting at 175 — 176° corre-
sponds with the 2-hydroxy-compound melting at 216°.

3 : i-DipIienyl-b : 5-dimethi/l-^^-cyc\openten-\-one-2-olj
^„ ^CHPh-CPh
CMe,<co— y.OH-

Five grams of the acetyl derivative (m. p. 137°) of y8^-dimethyl-
anhydroacetonebenzil were added to 50 c.c. of a 5 per cent, alcoholic
solution of potassium hydroxide. Where the alkali came in contact
with the solid acetyl compound, a bright green colour was observed,
which disappeared on shaking. A yellow solution was obtained,
which was kept at the ordinary temperature for several days. On
acidification, the 2-hydroxy-compound was precipitated, which crys-
tallised from alcohol, in which it is very soluble, in pink needles
melting at 155 — 156°. The yield was 4*2 grams:

01481 gave 0-4436 00^ and 0-0868 H2O. 0 = 81-68; H = 6-51.

CjgHjgOj requires 0 = 82-01 ; H = 6-47 per cent.
This substance dissolves in aqueous potassium hydroxide, from
which it is reprecipitated by carbon dioxide. Its alcoholic solution
gives with ferric chloride solution a dark brown coloration.

AND ITS DEIIIVATIVES. 2147

The phenylhydrazone crystallises from benzene in very sm\ll, yellow
plates, melting and decomposing at 244° :

0-1820 gave 0-5466 CO2 and 0-1152 HoO. C = 81-91 ; H = 7-03.
C25H24ON2 requires C = 81-52 ; H = 6-52 per cent.

The oxime of the isomeric 4-hydroxy-compound (/3/3-dimethyl-
anhydroacetonebenzil) crystallises from alcohol in large, prismatic
plates, melting and decomposing at 190° :

0-2554 gave 10-5 c.c. Ng (moist) at 17° and 761-5 mm. N = 4-77.
CjgHjgO.,N requires N = 4-77 per cent.

The oxime oi 4-acetoxy-3 : 4-diphenyl-5 : 5-dimethyl-A2-cyc^opentenone
crystallises from alcohol in fine, satiny, white needles, melting and
decomposing at 164° :

0-2746 gave 10 c.c. Ng (moi.st) at 19° and 772-7 mm. N = 4-26.
C.ijHo^OgN requires N = 4-17 per cent.

On methylation of the 2-hydroxy compound melting at 155 — 156°
with methyl iodide in the presence of sodium methoxide by Japp and
Klingemann's modification of the method (Trans., 1888, 53, 526),
2-viethoxi/-3 : i-diphenyl-b : 5-'iiineth//l-i:^"-cyc\o2)e7itenone was obtained ;
this crystalliees from alcohol in short needles, melting at 88-5°:

0-1430 gave 0-4308 CO.^ and 0-0890 H^O. 0 = 82-17; H = 6-92.
CgoH^gOg requires C = 82-19 ; H = 6-85 per cent.

Boiling with ethyl alcohol and sulphuric acid did not effect etheri-
fication.

On acetylation of the 2-hydroxy-com pound melting at 155 — 156°
with acetic anhydride and sulphuric acid at the ordinary temperature
in the usual way, there was obtained 2-acetoxy-3 : 4-diphenyl-
5 : 5-dimethyl-A--c7/c^opentenone, which crystallises from alcohol in
very slender needles, and from light petroleum in large, six-sided
plates melting at 92-5" :

0-1486 gave 0-4290 00^ and 0-0866 HgO. 0 = 78-72 ; H = 6-47.
OgjH.jfiOg requires 0 = 78*75 ; H = 6-25 per cent.

Hydrolysis of this ester by means of 5 per cent, alcoholic potash
regenerates the 2-hydroxy-compound melting at 155 — 156".

3 : ^-Diphenyl-^ : 5-diniethi/lcyc\opentanone,
CHPh-CH
CHPh-CMe^-^

A mixture of 10 grams of diphenyldimethyl-A--cyc^opontenon-2-ol
(ra. p, 155 — 156^), 15 grams of hydriodic acid (D 1-7), and 20 grams of
red phosphorus was heated to boiling for two hours. The product
crystallised from alcohol in large, prismatic plates, melting at 153°,
The yield wa$ about 5 grams.

2148 GRAY: ISOMERIDES OF ANHYDROACETONEBENZIL

Boiling for five minutes with concentrated hydriodic acid (D 1'96)
gives a small quantity of the same product, but most of the 2-hydroxy-
compound remains unchanged :

0-1462 gave 0-4626 CO,, and 0-1014 HgO. C = 86-28 ; H = 7-70.

CiqHooO requires C = 86-36 ; H = 7-57 per cent.
The oxime crystallises from alcohol as 4Ci9H2^0N,EtOH. The
alcohol of crystallisation is removed at 110°:

0-3620 gave 16-2 c.c. N., (moist) at 13° and 769 mm. N = 5-35.
CigHojON requires N — 5-0 per cent.

a-Desyli&ohulyric acid, COPh-CHPh-CMea'COgH.

Nine grams of the 2-hydroxy-compound melting at 155 — 156° were
mixed with 18 grams of potassium permanganate and aqueous
potassium hydroxide, and kept at the ordinary temperature. The
clear filtrate, on being acidified with hydrochloric acid, gave a
precipitate, which was dissolved in ether, and the ethereal solution was
shaken with sodium carbonate solution. The sodium carbonate
extract gave an acid, which was recrystallised from alcohol, and
melted, when rapidly heated, at 218°(!with evolution of gas :

0-1521 gave 0-4268 CO^ and 0-0880 H2O. C = 76-52 ; H = 6-43.
CjgHjgOg requires C= 76'59 ; H — 6-38 per cent.

Japp and Michie (Trans., 1903, 83, 309) synthesised a-desyl-
isobutyric acid (m. p. 218°), and a mixed melting-point test showed
the two acids to be identical.

On treating this acid with acetic anhydride and sulphuric acid at
the ordinary temperature, /3y-diphenyl-aa-dimethyl-A--crotonolactone
(m. p. 105 — 106°) was obtained, this being further proof of the
identity of the substance (Japp and Michie, loc. cit.).

a-Desyh'sobutyric acid was also obtained by oxidising an alkaline
solution of the 2-hydroxy-compound melting at 155 — 156° with
hydi-ogen peroxide. The product of this oxidation on meltihg yielded
a substance melting at 106°, and the author also found that a-desyl-
tsobutyric acid decomposed in the same way.

Py-Diphenyl-aa-dimethylbutyrolactone-ycarhoxylic Acid,
,CHPh-CPh-COoH
^CO 6

CMe,<"_.V- --■

Ten grams of the 2-hydroxy-compound melting at 155 — 156° were
dissolved in a solution of 60 grams of potassium hydroxide in 600 c.c.
of water. To this solution was added an alkaline solution of potassium
hypobromite, prepared by adding 30 grams of bromine to a solution of
60 grams of potassium hydroxide in 600 c.c. of water. The cold

AND ITS DERIVATIVES. 2149

mixture was kept for two days. A slight precipitate wliicli had
formed was then removed, and sulphur dioxide was passed into the
cold filtrate. A precipitate was obtained, and the precipitation was
completed by acidifying with dilute sulphuric acid. The solid was
dissolved in ether, and the ethereal solution was treated with succes-
sive portions of an aqueous solution of sodium carbonate and then of
an aqueous solution of sodium hydroxide. Practically nothing was
obtained in the sodium hydroxide extract. The sodium carbonate
yielded an acid which was difficult to purify by recrystallisation from
the usual solvents. The method finally adopted was to prepare the
pure potassium salt and to acidify its aqueous solution. The acid,
further purified by recrystallisation from dilute alcohol, separated in
needles melting at 197°.

It is very soluble in alcohol, acetic acid, or benzene, and insoluble
in light petroleum. The yield was about 5 grams.

When sodium hypochlorite was used instead of potassium hypo-
bromite, the yield was not improved. Other experiments, in which the
proportion of bromine was increased and the temperature raised to
that of the water-bath, led to similar results :

0-2014 gave 0-5118 CO2 and 0-1093 H,0. C = 69-3; H = 6-0.
CjgHgoOj i-equires C = 69-5 ; H = 6-0 per cent.

The acid crystallises with one molecule of water of crystallisation :

0-3510 lost 0-0190 at 113°. HoO = 5-4.

Cj(,Hjg04,HoO requires H20 = 5-5 per cent.

The crystals eflloresce appreciably even under ordinary conditions
of temperature and pressure, so that, unless the specimen analysed
has been quite recently prepared, the content of water is found
too low.

The silver salt was prepared :

0-2326 gave 00566 Ag. Ag = 24-33.

CjgHjgOjAg i-equires Ag = 24-82 per cent.

0-4534 of the acid required 7-22 c.c. of alcoholic sodium ethoxide
(1 c.c. = 000446 gram Na). M.W. (for a monobasic acid) = 324-5.
C19H20O5 requires M.W. = 328.

The acid is shown below to be a lactone of a-hydroxy-a/3-diphenyl-
yy-dimethylglutaric acid, C02H-CPh(OH)-CHPh-CMe2-CO,H. The
formation of a little of the sodium salt of this dibasic acid before
the neutral point is reached may explain the excess of alkali required
in the above titration.

The acid is inert towards acetic anhydride containing a few drops
of concentrated sulphuric acid, and towards boiling acetic anhydride.

On reduction with hydriodic acid and red phosphorus by heating for

2150 ISOMERIDES OK ANHYDROACETONEBENZIL.

tliree hours at 150° in a sealed tube, the acid gave /3y-diphenyl-aa-
dimethylbutyric acid, which was obtained by Japp and Michie
(Trans., 1903, 83, 311, 312), and also /3y-diphenyl-aa-dimethyl-
bntyrolactone. ' Both these products were identified by the mixed
melting-point test.

Sodium a- Uydroxy-aP-diphenyl-yy -dimethyl glutar ate,
COoNa-CPh{OH)-CHPlrCMe2-C02Na.

/?y-Diphenyl-aa-dimethylbut3'rolactone-y-carboxylic acid was dis-
solved in absolute alcohol, and a solution of sodium ethoxide in
absolute alcohol was added in excess of that required for the form-
ation of a dibasic salt. Phenolphtbalein indicated the point at which
enough podiam ethoxide was added to form the monobasic salt. When
excess of twice this quantity of sodium ethoxide solution had been
run in, and the solution had been gently heated, a bulky precipitate of
the dibasic salt was obtained. The pure white sodium salt was
collected and washed with absolute alcohol.

The salt crystallises with two molecules of alcohol of crystal-
lisation, which are partly lost in a vacuum over sulphuric acid, and
completely at 110° :

0-5820 gave 0-2218 NagSO^. Na = 12-36.

CjgHjgOgNag requires Na= 12-39 per cent:.

Enough water must have been present in the " absolute " alcohol
for the reaction to take place, as the dibasic salt is formed even if the
acid melting at 197° is free from water of crystallisation before use in
this experiment.

Action of Potassium Hydroxide on 3 : 4:-Diphenyl-5 : 5-dimethyl-
A^ cyc\openten-l-one-2-oL

Stilbene, identified by analysis, by the mixed melting-point test, and
by the preparation and analysis of the dibromo-derivative, was
obtained by boiling the 2-hydroxy-compound melting at 155 — 156°
with 50 per cent, aqueous potassium hydroxide. A small quantity
of a substance melting at 157" was also obtained.

The experiment was repeated with various percentages of the
alkali; with all the concentrations used (from 15 per cent, upwards), a
little of the substance melting at 157° was isolated ; with the lower
concentration*, the main bulk of the 2-hydroxy-compound was un-
changed, and no stilbene was formed ; with the higher concentrations,
stilbene was obtained, and the yield improve^ 9^5 the alkali concentf<\-
tion increased.

ELECTROMOTIVE HEHAVIOUR OF CUPROUS OXIDE, ETC. 2151

The research of this and the preceding; paper was suggested
by Prof. Japp, and the author wishes to thank him for the interest he
has always taken in the work.

The author also acknowledges the assistance rendered by the
Executive Committee of the Carnegie Trust for Scotland, who gave a
grant towards expenses.

ClIKMICAL Df.pahtmknt,

Univkksity of Abeudken.

CCXXXI. — The Electromotive Behavioui- of Cuprous

Oxide and Cupric Hydroxide in Alkcdine Electrolytes.

By Arthur John Allmand.

The object of starting this work was the determination of the solu-
bility product of crystalline cupric hydroxide, a constant of importance
in working out the chemistry of the basic salts of copper. The E.M.F.

I I Pt

of the combination Cu Cu(H0)2 alkali -p, was to be measured, and

hence the Cu" ion concentration deduced, and the solubility product
calculated in the ordinary way. On making measurements, however,
it was found that this combina^^ion gave values which varied very
considerably from liour to hour — which could, in fact, at no time be
reproduced with certainty. On consideration, this was recognised to
be due to the essential instability of the positive electrode owing to
the occurrence of the reaction Cu"+Cu — >- 2Cu*. The following
equilibria are involved :

(rt) Cu" + Cu :i:2Cir,

civing the relation L i. = K,

h to \^^ \

and

{h) Cu" + 20H'^Cu(HO)2.

with the relation [Cu"]*[OH']- = ^-,-, where ki is the solubility product
of cupric hydroxide.

If we multiply together the above two equations, we ^^et
[Cu'p-[0H']2 = ^v/r, and hence [Cu*]-[OH'j= Jk^

Let [Cu*]-[OH.'] =A-„ in a .saturated solution of cuprous oxide,
where k„ is the solubility product of cuprous hydi'oxide (cuprous
oxide).

Then in the present system if ^kiK is greater than k„, the cupric
hydroxide (solid phase) will disappear and form cuprous oxide at the

152 ALLMAND : ELECTROMOTIVE BEHAVIOUR OF CUPROUS OXIDE

expense of the electrode copper. That this actually is the case can
easily be shown experimentally. If a mixture of cupric hydroxide
and excess of finely divided copper is shaken up vigorously in a closed
vessel with sodium hydroxide solution, the cupric hydroxide will in a
few days be completely reduced to cuprous oxide. Now, when cuprous
oxide is once precipitated, we have a system with four components
(say, copper, oxygen, water, alkali), and with five phases (copper,
cuprous oxide, cupric hydroxide, solution, vapour), a system, that is,
with one degree of freedom. At a definite alkali concentration, this
can only exist in equilibrium at one definite temperature. At any
other temperature the potential difference Cu | Cu(II0)2 alkali will
depend on the relative velocities of the reaction Cu" + Cu — >- 2Cu*
and the deposition of cuprous oxide, on the one hand, and of solution
of cupric hydroxide, on the other.

Although an electromotive combination involving the reaction
Cu" — >■ Cu + 20 is, in general, unstable in alkaline solution,
combinations depending on the reaction Cu' — >- Cu+0, or the
reaction Cu" — >■ Cu' + ®, are stable.

Two such elements are the following :

Current in cell.

A. Cu I CugO alkali Hg | Pt

and

Current in cell.

B. Pt ! !^"(J?^^2 alkali H, ! Pt.

In combination A, the cathodic reaction for the passage of 96540
coulombs is briefly :

(a) Cu'-^Cu + ©

(6) KCuaO + HgO) -^ Cu' + OH' ;

the anodic reaction is :

(a) J-H, + ®— >H'

(6) H'+OH'-^HgO,

or, summing up, for the passage of two faradays the total result is
CU2O + Hg — > 2Cu + HgO.

The E.M.F. may be expressed as follows.

At the cathode :

Ecu. -> Cu = (E.P.)c„. _cu + 0-0.58 log [Cu']

= 0-454 + 0-058 log h - 0058 log [OH'j,
where kn, as before, is the solubility product of cuprous hydroxide.
At the anode :

E H- — II = (E.P.)h. — H + 0-058 log [H'j

= 0 + 0-058 log A«, - 0-058 log [OH'],

AND CUPRIC HYDROXIDE IN ALKALINE ELECTROLYTES. '2 153

where /■;,„ is the dissociation constant of water at the temperature in
question.

The total E.M.F. is hence :

Ecu- — cu-Eii- _ II = 0-454 + 0-0581og^" " (1).

From this, ^„ can be calcuhxtod.

In combination 7>, the following are the electrode reactions for the
passing through of one faraday.

At cathode :

(a) Cxi" — > Cu*+©

(6) Cu*+OH' — > ^(Ca.OfHjO).

Soliil.

Cu(HO)<,

-> Cu" + 20H'.

Solid.

A t anode :

(a) ^H,+ © — > H*

(6) H- + OH' — > HgO,

or, iiv the cell, for the passage of two faradays the total I'esult is :
2Cu(HO)2 + H.3 — > Cu„0 + 3H^0.
The corresponding E.M.F.'s are :

Ecu- -> cu- = (E.P.)cu" -> cu- + 0-058 logE^\*]

At liode. L*^^ J

= 0-204 + 0-0581og J"' -0-058 log [OH'].
Eh- _ II = (E.P.)h. -^ II + 0-058 log [H'].

At anode.

= 0 + 0-058 log /.-,„ - 0-058 log [Oil'].
That is,

jE'J/.i^' of cell = Ecu-— »Cu- - Eii-— >ii

= 0-204 + 0-058 log , ^*-^ (2);

hi is here, as before, the solubility product of cupric hydroxide, and
can be calculated, using the value of ko obtained from equation (1),

Two remarks apply to the above elements. Firstly, it should be
noted that the E.M.F. is independent of the alkali concentration, always
supposing it does not become sufllciently great appreciably to alter the
value of A;,,,, the dissociation constant of water.

Secondly, the first cell may be regarded as an Hg-Og cell,
in which hydrogen combines at atmospheric pressure with oxygen
supplied at the dissociation pressure at 17° of the reaction :
2CuoO ZZl 4CU + O2.

Before proceeding to the experimental part of the paper, a few
additional remarks are necessary. Firstly, it will be noticed that

21 .^4 AI.LMAND : ELECTROMOTIVE BEHAVIOUR OF CUPROUS OXIDE

potential differences (as in the above considerations) are referred to
the scale H., | X-H* =0. Also, that the potential of any hingle
electrode is taken as the potential of electrode minus potential of
solution. Secondly, the above calcal itious presuppose our knowledge
of the values (E.P.)ca" — -Cu- and (E.P.)cu' — ^ cu. The latter value
was obtained by Bodliinder and Storbeck iZaitsch. anory. Chem., 1902,
31, 1, 458) in the course of their work on the cuprous salts, as the
result of a long series of complex measurements and deductions. The
first value ia easily calculable by Luther's Law. A redetermination
of (E.P.)cu- — ' Cu from fresh and independent data would be of
importance. It might perhaps be thought that if the unstable cell
Cu I Cu(H0)2 alkali H.^ ] Pt were stable, and its E.M.F. could be
determined, then wo should have a third separate equation by means
of which this third unknown could be calculated. But even if the
combination were stable and measurable, we should not have a third
independent equation, for the E.M.F. in question (7r = 0'329 +
0029 log ki ~ 0058 log ku) can readily be calculated from the E.M.F.'s
of the cells already dealt with. Such a determination, even if
practicable, would thus merely confirm or otherwise the E.M.F. values
for the other two elements.

Experimental.

Two different alkalis, namely, sodium h) droxide and potassium
hydroxide, were used. Both were free from carbonate and were
prepared from metal. It was afterwards shown that small quantities
of carbonate made no final appreciable difference to the potential
values. The cupric hydroxide used was crystalline. Colloidal material
might be expected to give indefinite results (compare Dawson, this
vol., p. 370), apart from the gradual dehydration which would occur
in presence of alkali. Preparations were made according to the
methods of Becquerel {Compt. rend., 1852, 34, 573) and Btittger
{Jahresb., 1858, 198), which are stated by van Bemmelen {Ztitsch.
anorg. CJitvi., 1894, 5, 466) to^give undoubtedly crystalline products.
Two separate samples of each were prepared. The Becquerel prepara-
tion was seen to consist in the one case, when microscopically
examined, of pale blue, fine crystalline needles. For the second
sample, a higher power instrument was used, and the preparation
was seen to be composed of well formed prisms, with marked
birefringence and certainly not pseudomorphs. Ko trace of colloidal
matter could be detected. The crystals were slowly blackened by
.A'-potassium hydroxide at 25°, ^V/2-Pota6sium hydroxide was
practically without action, as also the iVyiO-alkali generally employed.
At room temperature, iV'/l -alkali was without effect. When shaken

AND CUPRIC IIYDUOXIDE IX AI.KAI.IN'K EI.ECTROLYTPLS. 21.55

for some weeks at 25^ with X/T-aiunionium hydroxide they bhickened.
They were uualtered by beiug left ovei- the week-end in a vacuutn
desiccator, and not affected by heating to 100° for ten minutes in an
air-bath or in boiling water. On analysis, after being heated to 100°,
they gave Cu = 6394: (determined as copper), H.,0 = l'J"67 (loss on
ignition), NO3 = 0'04 per cent, (colorinietrically as Nllg).

Katio, ' ' = 1-08.

[CuJ

The Bultger pi eparation was composed in both cases of particles of
rather doubtful crystalline nature, and of very irregular shape and
size. Some of them " stained " with methyl-violet solution, ami
many, when examined microscopically in polarised light, did not
react. On heating, or on treatment w-ith alkali, they behaved like
the Eecquerel prepai-ation.

Analysis of material dried at 100° gave : Cu = 64-1 6 ; HoO = 19-58 ;
SO^ absent.

Katio, [^jOj^j.Q^^
[CuJ

Cu(H0)2 requires Cu = 65-15 ; 11^0= 1846 per cent.

The above figures agree closely with analyses quoted by van
Bemmelen, who gives 19 4 per cent, of water in the Becquerel
and 19-6 per cent, in the Bottger preparations. As he further states,
the preparations aio slightly hydroscopic. The fact that the^e
substances contain some 8 per cent, more water than corresponds with
the ratio ICuO : IH.^0, is of interest, van Bemmelen is inclined to
attiibute the discrepancy to the presence of amorphous material. This
explanation might very well suffice for the case of the Bottger
pi eparations, but certainly does not hold in the case of the definitely
crystalline Becquerel products. The crystals are perhaps an
admixture of cupric hydroxide and some higher hydrate. In that
case one of the co-existing forms should disappear with time. Some
of the preparation was accordingly shaken at 25° for some weeks in a
dilute {^jl) solution of ammonia. The ammonia, by increasing the
solubility, should increase the rate of disappearance of the unstable
phase. The whole mass, however, dehydrated (see above), and no more
material was at that time available. This observation rather points
to the crystalline cupric hydroxide being unstable with respect to
cupric oxide and water at room temperature, and the influence of
electrolytes, such as ammonium hydroxide, potassium hydroxide, etc.,
in increasing the rate of loss of water might be possibly due to their
solvent action depending on complex ion formation or the slightly
amphoteric character of cupric hydroxide. Further investigation is
being devoted to this question.

^156 ALLMAND : ELECTROMOTIVE BEHAVIOUR OF CUPROUS OXIDE

The cuprous oxide was prepared by reducing an alkaline copper
sulphate solution with sucrose. The product, if rapidly and thoroughly
washed, is very pure.

Metallic copper was prepared by reducing finely-powdered cupric
oxide in a stream of hydrogen at a low tempei'ature.

Hydrogen (for the hydrogen electrode) was prepared from pure zinc
and dilute sulphuric acid ; it was washed with silver nitrate solution
and by concentrated alkaline potassium permanganate solution, passed
through a tube packed with cotton wool, and finally bubbled through
a wash-bottle containing the solution to be experimented on before
entering the electrode vessel.

It was found that constant values for the electrodes were not
obtained at once, but required in many cases considerable time.
Further, it is necessary to protect both systems from access of oxygen,
which materially alters their potentials. Electrode vessels of a simple
type were used. They consisted merely of a tube about 20 cm. in length
and 2 cm. in internal diameter, closed at the bottom and provided at the
other end with a well-fitting rubber stopper. A side-tube, one-third way
up, bent down at right angles and fitted with a tap, makes connexion
with the other half element, whilst the electrode is sealed into a glass
tube which enters through the rubber stopper. The electrodes used
were of blank platinum (occasionally platinised) or freshly coppered
platinum, the total area being 2 to 5 sq. cm. Connexions were made
by means of mercury.

The auxiliary electrodes used were hydrogen electrodes (alkaline
solution) and calomel electrodes of the ordinary type. Liquid
potentials when existing were always calculated by means of the
ordinary Planck formula. In the connecting vessel was used alkali of
the concentration experimented on at the time, and this was frequently
renewed.

The B.M.F.'s were measured by the Poggendorf method, and the
apparatus used — metre bridge, Weston cadmium cell, and galvanometer
— needs no particular description. All readings were taken at 17°,
the prevailing room temperature.

In setting up an electrode the depolariser used (a mixture of either
cupric hydroxide and cuprous oxide, or of cuprous oxide and copper)
wasfiUed into the electrode vessel to a depth of 1 or 2 cm., the
electrolyte poured in, the tap (greased) closed when the side-tube had
been filled, and then the electrode tube and rubber stopper inserted.
These were finally pushed down with the tap open, and the latter
closed only when all else was in position. One or two c.c. of air
remained in the vessel. After thoroughly coating the rubber stopper
with wax, the whole vessel was shaken overnight on an efficient
shaker and connected up for measurement in the ordinary way. When

AND CUPRIC HYDROXIDE IN ALKALINE ELECTROLV FES. 2157

about to take a reading, the tap was opened— otherwise kept closed.
On the first time of opening, a little alkali from the connecting vessel
entered to replace the oxygen in the electrode vessel absorbed during
shaking. This only happened once. Afterwards, all oxygen having
disappeared, there was no further contraction. This simple apparatus
acted very well, and the measurements were never disturbed by
entrance of oxygen from outside. As already stated, the single
potential differences did not become constant at once. They were read
several times daily, the vessels shaken overnight, and values not
taken as final until constant over three days.

It will be noticed that in the cells described above, there are no
liquid potential differences. This advantage was, however, negatived
when it was found that h}drogen electrodes in the alkali solutions do
not behave well, but give inconstant values which indicate insufficient
saturation of platinum by hydrogen, caused by slowness of absorption
or by the presence of some depolarising agent. Nothing very certain
appears to be known on this point. In the literature one finds con-
tiicting statements. Thus, Swale [Zeitsch. jjhysikal. Chein., 1894, 14,
577) obtained at 17° in ^/10-potassium hydroxide the value —0*749
volt; in A'/lO-sodium hydroxide the value -0*738; the theoretical
value, assuming 90 per cent, dissociation, is — 0758. With ^-potassium
hydroxide he found — 0*785 ; with iY-sodium hydroxide — 0'789 ; whilst
the theoretical value with sodium hydroxide, if the degree of dis-
sociation is taken as 0*72, is — 0*810 volt, and for potassium
hydroxide -0*812 volt, assuming 76 per cent, dissociation.
He attributed the discrepancies to impurities in the electro-
lytes. Wilsmore {Zeitsch. jjhysikal. Chein., 1900, 35, 291), who
demonstrated the reliable behaviour of hydrogen electrodes in acid
solutions, states that they are also constant in alkaline solutions.
Johnson {Trans. Amer, Eleclrochem. Soc, 1902, 1, 187) states tliat the
hydrogen electrode in alkaline solution is exceedingly sluggish in
reaching its final value. Lorenz and Hauser {Zeitsch. anorg. Cheni.,
1906, 51, 81), on the other hand, seem to have had a rather different
experience. Their values would appear to indicate supersaturaticn
with hydrogen. Lorenz and Mohn (Zeitsch. physikal. Chein., 1907, 60,
422), working with hydrogen electrodes in sodium and potassium
hydroxide, of different concentrations, after eliminating by calculation

Pt I
the liquid potentials, obtained for the „- ', alkali single potential

difference values which showed considerable di.^crepancies. With
potassium hydx'oxide were always obtained more negative figures than
with sodium hydroxide. Thus with iY-alkali, 0*006 volt ; with
iV/10-alkali, 0*007 volt; with AVlOO-alkali, 0*029 volt; with iV/lOOO-
alkali, 0*011 volt; whereas in A'^-alkali the difference should be only
VOL. XCV. 7 C

2158 AI.LMAND : ELECTROMOTIVE BEHAVIOUR OF CUPROUS OXIDE

two luilli-volts, and for the higher dilutions should nob exist. The
latest workers using the electrode are Luther and Pokoniy (Zeitsch.
anorg. Chem., 1908, 57, 290) and Bronsted {Zeilsch. physikal. Ghem.,
1909, 65, 84). They give no single potential difference measurements
but their experience was evidently a satisfactory one.

The author's results point to the electrode being an untrustworthy
one. ^Vorking with iV/10-alkali, ho has generally obtained — 0'748
to — 0'754 volt (theoretical - 0'758). Sometimes values far less
negative were obtained, such as —0735. Sometimes values a few milli-
volts more negative than the theoretical value were obtained, as - 0"762,
although figures were never reached as much on the negative side of the
theoretical as Lorenz and Hauser obtained with the -A^-alkali electrode.
The readings were often attained slowly, and varied irregularly with
time and the speed of the gas through the electrode vessel. Sometimes
abnormal readings were obtained, such as - 0"710 volt. These could
be avoided by boiling the electrode in water immediately before use.
And, generally speaking, this treatment tended to rapid setting up,
more negative values, and more constant results. But the effect was
by no means a certain one. Possible action of oxidising impurities in
the alkali was eliminated. The influence of the presence of an oxide
of platinum in the platinum-black of the electrode was at one time
suspected, but this could not be proved, nor could the hypothesis be
quite reconciled with the behaviour of the electrode on heating, boiling,
etc. A few experiments were carried out using iV^-alkali. The
results deviated considerably from the theoretical value, but it was
noticed that during each separate experiment they showed better
constancy.

Calomel electrodes were consequently used for the measurements
described in this paper.

Results.

The experiments first described were carried ont with iV/10-alkali
as electrolyte. Both sodium hydroxide and potassium hydroxide
were used, and the half-elements were, as a rule, set up in duplicate.
In stating the results, the conventions as to sign and zero already
mentioned are used. The potential of the decinormal calomel elec-
trode is taken as -f 0"335 volt at 17°, the liquid potential differences,
iVyiO-potassium hydroxide and iV/10 sodium hydroxide minus iV/10-
potassium chloride, as 0015 volt and 0*020 volt respectively.

The following tables contain the results obtained :

AND CUPRIC HYDROXIDE IN ALKALINE ELECTROLYTES. 2159

Table I.

-Teviperaiure = J 7°.

Current in celL

Ht

Alkali
Alkali

N:iOH
KOH .

Hg.,Cl..iV/10-lvCl I iV/lO-
alkali Cn.,0 | Cu.
/0-r.t»6 V(.lt\

lo-i;oi ,, i
/o-()Ori ,, )
lo-Gor. ,, J

Mean

Cu I Cu,O.V/10-
alkali.
-0-283 volt
-0-2S6 ,,
-0-285 ,,
-0-285 ,,

0-285 volt.

In the above table, the one column contains the E.M.F. of the
actual working combination ; the other contains the single potential
difference which constitutes the cathodic portion of the cell A (^ee
p. 2152).

Table II. — TmipercUure = 17°.

-Current in cell.

Cu(HO)., (BUttger) :

InNaOH

In KOH

Cu(HO)., (Becquerel) :
InNaOH

In KOH

Hg„C!.,A710-KCl j AyiO-alkali

Cu(HO)., I p p

Cu,,0 I ^ ^- ^ ^

ro"-327 volt

\ 0-328 ,,

^0-338 ,,

\ 0-333 „

g;;<™)-W/10-a]kali.

-0-012 volt
-0013 ,,
-0-018 ,,
-0-013 .,

Mean .

f 0-329 volt
10-334 „
fO-343 ,,
\ 0-335 ,,

-0-OM volt

-0-014 volt
-0-019 „
-0-023 ,,
-0-015 ,,

Mean .

-0-018 volt

In table II, the first column, as before contains the obsei'ved
E.AI.F.'s against calomel electrodes, whilst the second column con-
tains the single potential difference which forms the cathodic com-
ponent of the combination B (see p. 2152).

With the aid of the above values, and assuming that the leversible

Pt I
P.D. t^ iV/10-alkali is - 0-758 volt at 17°, we calculate the following

figures for the EM.F.'s of the cells mentioned at the beginning of
this paper.

Cell A.

Cell B.

(Bottger Cu(HO).,)

Cell B.

(Becquerel Cu{HO).,)

Pt
Pt

CuoO.V/lO-alkali
C»(»O)w/10-alkali
'W/10-alkali

CUnO

Cu(HO),
CuoO

Pt
H,

Pt

H2
Pt
H,

0-473 volt
0-744 „
0-740 ,,

The effect of altering the concentration of the alkali was next
studied., Experiments were carried out with iV-sodium hydroxide

7 C 2

2160 ALLMAND: ELECTROMOTIVE BEHAVIOUR OF CUPROUS OXIDE

and iV-potassiuui liydroxide, and the following tables contain the
results. The potential of the iV^calomel electrode at 17° is taken as
+ 0'282 volt, and the liquid potential differences, iV-potassium
hydroxide minus iV^-potassium chloride and iV^-sodium hydroxide minus
^'-potassium chloride, as 0*015 volt and 0*020 volt respectively.

Alkali
XaOH

Alkali
KOH

Table III. — Ternperature=\T

-< Current in cell.

Hg I Hg.ClaA^-KCl | i\^-alkali CuoO | Cu.
C0'604 volt
|o-C06 ,,
'l 0-605 ,,
l0-607 „

Mean.

Cu I CuoO.V-alkali.
-0-342 volt
-0-344 ,,
-0-343 „
-0-345 ,,

0 613

- 0 344 volt
-0-346 „

Alkali
NaOH

Alkali
KOH

Table IV. — Temperature = 17°.

-< Current in cell.

Hg I Hg2Cl.,i\^-KCI I lY-alkali Cu^o ^^' I P*-

(-0-337 volt (Bottger)
1 0-835 ,, (Bottger)

'j 0-336 ,, (Becquerel)\ Platinised platinum
i 0-337 ,, (Bottger) J electrodes

Pt|C»(HO).^.,lkali,

-0"'-075 volt
-0-073 „
-0-074 „
-0-075 „

Mean.

0-343

-0-074 volt
-0-076 ,,

A few points arising out of tables III and IV should be noticed.
Firstly, the single potential difference values obtained with potassium
hydroxide as an electrolyte are in both cases more negative than those
given with sodium hydroxide. This can be directly ascribed to the
greater OH' ion concentration in the potassium hydroxide solution,
with its coi-respondingly smaller metal ion concentration. The
difference, 2 milli-volts, is equal to the calculated* one. Secondly, in
table IV, no difference can be detected between the behaviour of the
Becquerel and Bottger preparations. Thirdly, two of the measure-
ments in table IV were carried out with platinised instead of blank
platinum electrodes. The results were the same.

If we now take, as before, the P.D.'s tt
Pt

iV^-NaOH as -0-810 volt

and

H„

.V-KOH as -0-812 volt, we deduce the E.M.F. of cell

A to be (0-810— 0-344) or (0-812—0-346) volt— that is, 0-466 volt.
Similarly, that of cell B is (0-810—0-074) or (0-812— 0-07G) volt,
equal to 0736 volt.

In both cases these values are six or seven milli-volts or so lower
* See also calculated values lor hydrogen electrodes on page 2157.

AND CUPRIC HYDROXIDE IN ALKALINE ELECTROLYTES. 2161

than those given by the iV/10-electi'odes. As the P.l). of the H,-
electrode half-element in both cases is calculated, the discrepancies
must lie in the experimentally determined electrode values. This is
the case. Assuming the value Cu | CugOiV/lO-alkali = — 0*285 volt to
be correct, one would expect for Cu | CugOA^-alkali the value
— 0-285 — 0-052 volt =- 0-337 volt, whereas —0-344 was the figure
experimentally determined. Now, the electrodes of both typos experi-
mented on, in both alkalis and in both strengths of alkali, invariably
commenced by giving a higher positive value than the final value
quoted in the tables. This corresponds, in electrodes of the type

Pt p .-.^'^ alkali, with an initial Cu" ion concentration greater

than the equilibi'ium value, and in electrodes of the type Cu | CugO
alkali to a corresponding lax-ge Cu* ion concentration.* The change
with iV-alkali was far more rapid, and, as we see, lower final values
were obtained than those calculated, assuming the iV/10 values to be
correct. A possible explanation of the fall of potential may be that
the initial values correspond with particles of very fine grain and
therefore of greater solubility, and that those are gradually removed
and re-deposited in lai-ger size. This view derives support from the
fact that both cuprous oxide and cupric hydroxide are slightly
amphoteric and can function as weak acids. Their solubility as anion
in the alkali will thus increase with the concentration of the alkali,
and hence the rate of change to the stable form should increase with
the increase of alkali concentration, which is exactly what happens.
With iV/10-alkali the last stages of the change may proceed so very
slowly that the values observed during the experiments may never
quite have reached equilibrium values. To test further this
hypothesis, one sample each of Bottger and Becquerel hydroxides were
re-examined microscopically. The Bottger hydroxide contained a
large mass of material of ayerage size 0-5 — O-8/a. The Becquerel
hydroxide contained many particles 1 — 2fx. in length. A sample of
cuprous oxide (beautifully crystalline) showed a few crystals only
<^2fi. The great majority were of the order of 5/jl. We know from
the work of Hulett [Zeitsch. physikal. Chem., 1901, 37, 385) that
in those cases which have been examined, the solubility of a
powder containing particles of size <^2yu, is dependent on variations
in that size. The most striking case is that of mercuric oxide, the
solubility of which can actually be increased threefold by suitable
mechanical treatment. In the case of both samples of cupric
hydroxide, we can fairly suppose these influences to come into

* This fall in P.D. is still more marked with electrodes containing cupric oxide
instead of cupric hydroxide as depolariser, experiments with which are now being
carried out.

•21 ()2 ALLMAND: ELECTROMOTIVE BEHAVIOUR OF CUPROUS OXIDE

play. Whether cuprous oxide is also effected is less certain. Now let
us finally consider the effect a reasonable increase in solubility would
produce on the potential difference measured, and take as an example

the Pt J; p.'- alkali electrode. The process occurring here is

Cu" —^ Cu' + ©. The single P.D. is const. +0-058 log ^— volt.

Cu

We see that an increase in the Cu' concentration would actually
diminish the P.D. But we know that such an increase, if any, must
be small. We will here neglect it. Consequently the single potential
difference will be increased by 58 log C milli-volts, where C is
the ratio of the Cu" concentration to the normal equilibrium
concentration. To take an extreme case, suppose C = 3, as with the
mercuric oxide mentioned above. Then increase of P.D. = 58 x 0*477 =
27 milli-volts. Giving C various smaller values, we obtain the
following table :

Table V.

C. Increase of P. D.

3 0-027 volt

2-5 0-023

2 0-017

1-5 0-010

1-2 0-005

1-1 0-002

If we assume that the values finally obtained with the iV-alkali
electrodes are 'correct, the final values of the iV/IO-alkali electrodes
are about seven milli-volts too high. Their average fall before being taken
as constant was perhaps another 5 — 7 milli-volts. The depolarisers,
therefore, in their initial states gave values 14 milli-volts too high.
This would correspond with a value of C of about 1-7, which is quite
conceivable. Only a small fraction of the original depolariser is
supposed to have been in this finely-divided state.

For purposes of calculation, although the lower values for the
E.M.F.'s of the elements A and B are probably the more trustworthy,
we will take the mean of the two sets of figures, and obtain,
therefore,

E.M.F. oi A = 0-469 volt.
E.M.F. of ^ = 0-738 volt.

If the above values be now substituted in equations (1) and (2), the
solubility products mentioned at the beginning can be calculated.
Taking ky, (the dissociation constant of water) as 0-56 x 10~^* at room
temperature, we obtain :

ko (for cuprous oxide) 1-0 x 10"^*.
ki (for cupric hydroxide) TO x 10"^^.

AND CUPRIC HVDROXIDE IN ALKALINE ELECTROLYTES. 2 103

The solubilities (^ ^ 1 in pure water at 17° work out at

V litre J ^

0*5 X lO"" for cuprous oxide and 3x10""' for cupric hydroxide,

assuming both to be in solution as completely dissociated bases only.

We are now in a position to see clearly the essential instability of

the system Cu | Cu(H0)2 alkali. For if K (see p. 2151) be taken as

0-5 X lO""* (Bodliinder and Storbeck) and ki as 10 x lO^^'', then

JK/ci = VO-5 X 1-0 X 10-23 = 2-2 x lO"!-.

This considerably exceeds the value for k,, givei^ above. Cuprous
oxide will consequently be precipitated at ^the expense of the cupric
hydroxide and the electrode copper.

It has already been pointed out that the element A is in reality an
Hg-Og cell working with a low but definite oxygen pressure.
And from its E.M.F. can be calculated the dissociation pressure at
17° C. of the reaction :

2Cu20^4Cu + 02.

Taking 1-232 volts as the E.M.F. of the ^2-02 cell with both
gases at atmospheric pressure, we have

0058
0-469=: 1-232+ ^ log Par

, 0-763x4

= 53-4.

.-. po2 at 17° = 3 X 10-53 atmospheres for 2CU2O ^I^ 4Cu + O2.

From this value, using equations developed in Haber's " Thermo-
dynamics of Technical Gas-Reactions," the author has calculated the
temperature at which the dissociation pressure of this reaction would
become equal to 0-21 atmosphere, the temperature, that is, at which
cuprous oxide would commence to lose oxygen when heated in air.
The simplified * equation 26 (page 69. English edition) gives as this
temperature 1929° abs., that is, 1656°. If use is made of equation 15
(page 61), in which variations in the reaction heat with temperature
are taken into account, a slightly higher temperature will be obtained, t
Thus at 1900° abs. the system according to equation 26 will have
a pressure of 150 mm. ; according to equation 15, one of 45 mm. only.
With these figures we will now compare values calculated by using
the formula dei'ived by Nernst. For dissociations in which oxygen is
involved it runs :

log;'02 = ^-;^,+ l-75 1og2^+(7,

where C = 2-8.

* Constant involved = -39-2. t Constant involved = -46-1.

2164. AIJ.MA.VD: ELECTROMOTIVE BF.IIAVIOUR OF CUPROUS OXIDE

Putting in (? = 81600 and T= 290,

we get log;?„2= -54-5 = 55'5.

Hence ;?02 = 3 x lO-^s atmospheres at 17° for 2CU2O :=: iCu + Oa-
The agreement (comparing the logarithms) is remarkably good. But
at higher temperatures it is still more striking. Stahl {Metallurgie, 1907,
4, 682), using the same formula, has calculated, as the author has done
above, the temperature at which the pressure of the system becomes
equal to 0*21 atmosphere. He gets the value 1662^, whilst using
Haber's simplified formula and the results of the electromotive measure
ments, the almosi? identical value of 1656° has been obtained. We
are unfortunately not in possession of any experimentally determined
values. Foote and Smibh [J. Amer. Chem. Soc, 1908, 30, 1344) have
recently shown that the dissociation pressure does not exceed 1 mm.
at 1020°.

It should be pointed out, however, that any dissociation pressures
which may be observed in the future will probably be greater than
those calculated by the Nernst or Haber formulfe. The reason is that
the calculated values refer to the equilibrium between cuprous oxide,
superheated solid copper, and oxygen, whereas the experimentally deter-
mined figures would hold for cuprous oxide, fused copper saturated
with cupi'ous oxide, and oxygen. Both because of its being fused and
because of the dissolved oxide, the vapour pressure of the copper
entering into the equation :

{pCu^of

will be less than in the calculated value, and hence the oxygen
pressure correspondingly greater.

Apart from the dissociation pressure of the system 2CU2O Z^

4C'u + 0.,, there is another magnitude expei-imentally determined in

this paper which can be calculated on the lines indicated by Nernst.

That is the E.M.F. of the cell A, which corresponds with the reaction :

Cu^O + H2 -^ H2O + 2Cu.

The first calculations of E.M.F.'s, from thermochemical data, working
with the Nernst thermodynamical theorem were made by Halla
{Zeiisch. Elektrochem., 1908, 14, 411). They only referred, however, to
conden.sed sy.stems of the type Pb + 2 AgCl — > PbClg + 2 Ag. Nernst
{Sitzungsber. K. Akad. Wiss. Berlin, 1909, 247) himself in a later
paper has extended the calculations to electromotive systems in which
gases can take part, such as correspond with the reactions :

Hg + HgO -^ HaO + Hg and Ho + CU -^ 2HC1.
To the first of these the element at present under discussion is strictly
analogous. To avoid using in his calculation the specific heat of
supercooled water, a quantity not accurately known, Nernst has

combination Cu CugO alkali

AND CUPRIC HVOROXIDE IX ALIvAIJNE ELECTROLYTES. 2165

calculated the E.M.F. of the combination Hg HgO alkali ^ at 0*^,

thus obtaining ice as one of the resultants of the reaction. He has

compared the value obtained — 0'880 volt — with a figure which is

obtained by extrapolating Brijnsted's i^oc. cit.) results to 0°, namely,

0*934 volt. The discrepancy is thus rather considerable. In the

present case, there are no available data from which the E.M.F. of the

Pt

jr at 0° can be obtained. It was not

thought worth while to measure the half-element Cu | CugO alkali at
0°, because there are no existing figures on the temperature-coefficient
of the hydrogen electrode or its value at 0°. This could, indeed, be
calculated, but not with any great degree of certainty, from other
exi.sting data. That as a matter of fact it makes but little difference
if the calculation does involve the specific heat of supercooled water
can be readily shown. Thus for

HgO-f-H2— >Hg + H20
we have

Q = 63200 - 21500 = 46700 at 290° abs.
Also

^, = 3-5 -h 2y8.290 = 6-8 + 1 1 -2 - 18-0 - 6-8 = - 6 -8.

Hence

Therefore

580 (i = -10-3. |8 = -0-018.

46700 = ^,-f 3-5.290 -0-018.(290)2
Qo = 46700- 1015 -f- 1514 = 47200.

^ 0-0001983.290/ 47200 0-018.290

^= 2 (wT:^-1-'^1<>»- 290+^^:^^-1-6

0-0001983.290
= 2 (35-61-4-31 + 1-14-1-6*)

^0^198^0.^3^.3^^^ ^.33^ ^^^,^_

This must be compared with the figure given by Bronsted for room
temperature, namely, 0929 volt.t We see that the discrepancy
although still considerable, is no worse, but rather less. The

calculation of the E.M.F. of the cell Cu CuoO alkali

fore carried out for room temperature.

The reaction is Cu.^O + Hg — > 2CU + H2O.

TT is there-

J^2

* Ncrnst, Zeitsch. Elcktrochcm., 1909, 15, 687.

t Measiu-ements of the author (about to be published) give 0-925 volt for room
temperature.

2166 ELECTROMOTIVE BEHAVIOUR OF CUPROUS OXIDE, ETC.

We have (H^.O) = 68200 + (H.O)

(2Cu,0) = 40800 + (CiigO).

Hence (3290 = 27400.

The molecular specific heats involved are (Ho) = 6"8; (H20) = 18;
(Cu.p) = 15-9; (2Cu) = 121.
Therefore

^, = 3-5 + 2/?r= 6-8 + 15-9 -18-0- 12 •!= -74.

2ySr=-10-9. /?= -0-019.
Therefore

27400 = $„ + 3-5.290 -0-019 (290)2

Qo = 27400-1015 + 1600 = 27980.
Hence

0-0001983.290/ 27980 0-019.290

E =

(4^571:295 - 1-^5 log. 290 + ^^jl— 1-6)

2

0-0001983.290
= ^ (21-11 - 4-31 + 1-20 - 1-6)

0-0001983.290 ,_ _, ^ ,„^ ,
= 2 (16-40) = 0-472 volt.

The agreement is all that could be wished.

It should finally be mentioned that several workers have measured
electrodes of the types described in this paper. For example,
Immerwahr (Zeitich. anorg. Chem., 1900, 24, 269), in her investigation
of the copper ion concentrations in saturated solutions of sparingly
soluble copper salts, used the combination Cu | Cu(HO)o (colloidal)
alkali. She found it impossible to calculate a solubility product for
the cupric hydroxide, owing to the rapid change of potential. This
was attributed to dehydration to cupric oxide, but it is obviously
to be partly ascribed (in light of present results) to the change
Cu'* + Cu — >- 2Cu'. Lorenz and Hauser {loc. cit.) and Johnson {loc.
cit.) have both worked with the electrode Cu | CugO alkali. For the

Pt

combination Cu

CuoO alkali

„ , the former workers found values

of 0905 to 0-932 volt, whilst Johnson found 0-438 volt; both
figures are considerably different from the 0-469 volt given in this
paper.

Summary of Results.

(a) The system copper-cupric hydroxide-alkali is shown to be
unstaVjle.

(6) Cells containing the stable systems copper, cuprous oxide, alkali
and platinum, cupric hydroxide, cuprous oxide, alkali have been
measured.

ROBINSONT: A NEW SYNTHESIS OF OXAZOLE DKIJI VA 11 VIvS. 21G7

(c) Pjxisting data as to the untrustworthiness of the hydrogen
electrode in alkaline solution are confirmed.

(d) The solubility products of cuprous oxide and cupric hydroxide
are calculated.

(e) The influence of size of grain of depolariser on electrode
potentials is emphasised.

(/) The dissociation pressure at room temperature of the reaction
2CU2O :^i 4Cu + 0^, is calculated, and shown to be in fair agreement
with the value obtained by calculating with Nernst's formula.

(g) The temperature is calculated at which cuprous oxide will
dissociate in air according to the above equation, and is shown to give
the best of agreement with the same value obtained using Nernst's
formula.

Pt

(h) The E.M.F. of the element Cu CugO alkali tt has been

calculated in the way shown by Nernst, and the result is again in
excellent agreement with that experimentally determined.

The author wishes to offer his best thanks to Prof. Donnan for the
continued interest shown, and the valuable advice given, daring the
course of this work,

MuspRATT Laboratory ov Physical Chejiistry,
University of Liverpool.

CCXXXII. — A New Synthesis of Oxazole Derivatives.
By Robert Robinson.

During the course of a synthetical investigation, the author had
occasion to prepare w-phenylacetylaminoacetophenone,

COPh-CHj-NH-CO-CHoPh,
and noticed that this substance, under the influence of concentrated
sulphuric acid, readily loses the elements of water with the production
of a feeble base of the formula Cj^^HjgON. The probable explanation
of this interesting change is that this compound, reacting in its enolic
form,

0H-CPh:CH-N:C(0H)-CH2Ph,

loses water from the two hydroxy-groups, and the base obtained
would then be 5-phenyl-2-benzyloxazole,

^CPh=:CH^

21 (iS ROHINSON : A NEW SYNTHESIS OF OXAZOLE DERIVATIVES.

That the reaction really does take this course was proved by
examiniug wbenzoylaminoacetophenone, a substance which was easily
obtained by benzoylating w-aminoacetophenone. On treatment with
concentrated sulphuric acid, this compound was found to yield 2 : 5-
diphenyloxazole, identical with the base prepared by Emil Fischer
(Ber., 1896, 29, 205) by the condensation of benzaldehyde with its
cyanohydrin under the influence of hydrochloric acid. The same base
is also obtained by heating bromophenylacetaldehyde with beuzamide
(E. Fischer, Ber., 1896, 29, 213).

The production of 2 : 5-diphenyloxazole from w-benzoylamino-
acetophenone is a clear proof that in the synthesis of oxazoles from
bromo-ketones or aldehydes and acid amides, the hydrogen of the
amino-group condenses with oxygen of the carbonyl group rather than
with the bromine. Thus, for instance, the reaction between bromo-
acetophenone and benzamide does not involve the intermediate forma-
tion of benzoylaminoacetophenone, since it is the 3 : 5- and not the
2 : 5-diphenyloxazole which is produced (Bliimlein, Bei\, 1884, 17,
2580 ; Lewy, Be^-., 1887, 20, 2579).

The synthesis may be represented as follows if both the bromo-

acetophenone and the benzamide are assumed to react in the enolic

form :

CPh-OH HO-CPh ,^^ CPh-0'CPh
II + II = H„0 -H 1 1 II

CHBr HN ^ CH NHBr

2 : 5-Diphenyloxazole and, to a much greater extent, its dimethoxy-
derivative (see p. 2172), exhibit blue fluorescence in alcoholic
solution.

The introduction of the methylene group between the oxazole ring
and the phenyl radicle gives rise to oxazoles which are not
fluorescent. Evidently the occurrence of this property is dependent
on an uninterrupted chain of conjugate double linkings connecting
the aromatic nuclei through the oxazole ring.

The method of synthesising oxazole derivatives described above in
the case of 2 : 5-diphenyloxazole has been tested in various cases,
and is probably of very general application, but at least one case in
which ring formation does not take place has been observed.

2-Benzoylamino-5 : 6-dimethoxyhydrindone,

is unchanged by solution in sulphuric acid for half an hour, and this
is remarkable in view of the ease with which the closely allied
w-benzoylaminoacetoveratrone undergoes the transformation. It is the
author's intention to apply this method of oxazole formation to the

ROBINSON: A NEW SYNTHESIS OF OXAZOLE DERIVATIVES. -iUiO

synthesis, uot ouly of the unknown parent of the group itself, but
also of some of its more important derivatives.

In the meantime a number of new substances are described, which
it was necessary to prepare in order to test the applicability of the
above synthesis.

Experimental.
(ji- Benzoyl aviinoacetopheno.iie, COPh'CHg'NH'COPh.

This co.'apound is very readily obtained under the following con-
ditions : w-Aminoacetophenone hydrochloride (5 grams) is dissolved in
water (50 c.c), the solution vigorously stirred, and treated with
benzoyl chloride (7 grams) and sufficient aqueous potassium hydroxide
(40 per cent, solution) to keep the liquid alkaline.

When all the benzoyl chloride has been decomposed, the oil solidifies,
Tbe almost colourless,-, crystalline mass is collected, washed with
water, and a small quantity of oily impurity removed by contact with
porous porcelain.

The colourless substance may be recrystallised from alcohol, and
separates in beautiful needles, melting at 123" :

0-1202 gave 0-3322 COg and 0-0608 HoO. C = 75-4; H = 5-6.
CjjHjgOoN requires C = 75-3 ; H = 5-4 per cent.

« . x^. , , r ^ .CPhlCH

2 :5-Dtphenyloxazole, 0<C^^, . ' .
'^ "^ ^CPh.N

Benzoyl-co-aminoacetophenone (1 gram) was dissolved in concen-
trated sulphuric acid (5 c.c), and the solution warmed on the water-
bath for two minutes and then poured into water.

The colourless, crystalline precipitate, after collection and crystall-
isation from light petroleum (b. p. 50 — 70°), melted at 73°, whilst
the melting point of 2 : 5-diphenyloxazole, prepared from benz-
aldehyde and benzaldehydecyanohydrin, is 74° (E. Fischer, £er.,
1896, 29, 207). The identity of the two substances was further
proved by a careful comparison of the products, as well as by the
fact that a mixture of them melted at 73°.

Since 2-phenyl-5-veratryloxazole exhibits marked blue fluor-
escence in benzene solution, it was of interest to examine 2 : 5-
diphenyloxazole in this respect.

It was found that, although this property is difficult to observe in
ordinary light, yet by the light of burning magnesium the alcoholic
or benzene solution of this substance shows strong violet-blue
fluorescence.

•2170 ROBINSON: A NEW SYNTHESIS OF OXAZOLE DERIVATIVES

(n-Fhenylacetijlaminoacetophenone, COPh'CHg'NH-CO'CHoPh.

This substance was prepared in considerable quantities for some
synthetical experiments, and the following process was found to be
expeditious.

co-Aminoacetophenone stannichloride (50 grams) is dissolved in hot
water (250 c.c.) and the solution cooled, and treated with phenyl-
acetyl chloride (30 grams) and then with aqueous potassium hydroxide
(175 c.c. of a 40 per cent, solution). The rise in temperature is
checked by the addition of small pieces of ice, and the liquid must
be thoroughly stirred by mechanical means. The end of the reaction
is indicated by the crystallisation of the product, and, after dilution
with water, the pale yellow crystals are collected and crystallised from
benzene, ether, or alcohol.

The purest product is obtained from ether; colourless needles or
prisms, melting at 104° :

0-1235 gave 0-3424 COg and 0-0680 H^O. C = 75-6; H = 6-l.
C^gH^.OgN requires C = 75-9; H = 5-9 per cent.

The oxime crystallises from benzene or dilute alcohol in prisms, or
from ethyl acetate and light p etroleum as a highly characteristic
mass of balls of minute threads. It melts at 154°, and was found to be
unaltered by solution in concentrated sulphuric acid for a short
time. Longer action induces so me change, but it was not found
possible to isolate the expected six-membered, heterocyclic substance.

On analysis, after drying in a vacuum :

0-1217 gave 10-9 c.c. N2 at 12° and 765 mm. N = 10-7.
C^gHjgOqNo requires N= 10-4 per cent.

The pJienylhydrazone, when recrystallised from alcohol, forms a
beautiful, satiny powder, which under the microscope is seen to
consist of curious crystals, shaped like a flower with four large
petals. This derivative melts at 184 — 185°, and shows a great
tendency to change into a yellow oil, especially under the influence of
heat :

0-1222 gave 12-8 c.c. ^^ at 150° and 754 mm. N= 12-2.
CggHgjONg requires N = 12-2 per cent.

5-Phenyl-2-henzyloxazole, CxCp/p^pi ^^N.

w-Phenylacetylaminoacetophenone (2 grams) was dissolved in cold
concentrated sulphuric acid (10 c.c), and the solution kept for two
hours. On adding water in excess, a crystalline precipitate is ob-
tained, but time must be allowed for the milky fluid to deposit the

ROBINSON: A NEW SYNTHESIS OF OXAZOI.E DERIVATIVES. 2171

whole of the substance in a solid condition. On crystallisation from
light petroleum, magnificent long, flat needles, melting at 89°,
separate.

In common with the other oxazole derivatives described in this
paper, this substance is readily soluble in most organic solvents,
but sparingly so in boiling water or cold light petroleum :

0-1300 gave 0-3891 CO., and 0-0639 HgO. C = 81-G ; H = 5-5.
Cn,H,30N requires C = 81-7 ; H = 5-5 per cent.

Under no conditions was fluorescence observed in the solutions of
this substance.

The picrate forms pale yellow prisms, readily soluble in alcohol,
melting at 103°:

0-1173 gave 11-G c.c. Ngat 10°and 7G8 mm. N = 12-0.
CggH^jjOgN^ requires N = 12-1 per cent.

a-Hydroxy-P-phenylacetylamino-a-phenylethane,
OH-CHPh-CH.3-NH-CO-CH2Ph.

w-Phenylacetylaminoacetophenone (10 grams) was dissolved in
methyl alcohol (150 c.c.) and water (50 c.c). The solution was
vigorously stirred and treated with sodium amalgam (300 grams of
3 per cent.), added gradually during three hours. A neutral reaction
was maintained by a stream of carbon dioxide, and the reduction was
completed in four to five hours. The liquid was filtered to remove
sodium carbonate, and then diluted with twice its volume of water.
A crystalline precipitate slowly separated, which, when recrystallised,
first from benzene and finally from dry ether, formed hard, colour-
less prisms, melting at 99° :

01198 gave 0-3291 CO2 and 0-0747 H2C. 0 = 74-9; H = 6-9.
CjgHiH.02N requires C = 75-3 ; H = 6-6 per cent.

Unsuccessful attempts were made to cause this sub.«tance to give
up the elements of water so as to produce a dihydro-oxazole deriv-
ative. Thus the action of concentrated sulphuric acid is either so
mild that the compound may be recovered unchanged, or so vigorous
at higher temperatures that there is complete decomposition. If a
solution in concentrated sulphuric acid is warmed for two minutes on
the water-bath, then diluted with water and boiled, a very strong and
characteristic odour of phenylacetaldehyde is observed. The form-
ation of this substance is clearly due to the elimination of water so as
to form the compound

CHPh:CH-NH-C0-CH2Ph,

which, in turn, is further hydrolysed, yielding phenylacetaldehyde,
ammonia, and phenylacetic acid.

•2l~'2 1U)H1NS0N: A NEW SYNTHESIS OF OXAZOLE DEKIVATIVES

This alcohol is also surprisingly stable towards phosphoric oxide in
boiling benzene solution. In one experiment a 10 per cent, solution
in benzene was boiled for one and a-half hours with a large excess of
phosphoric oxide. On decomposing the product with ice, a consider-
able quantity of the unchanged substance was found in the aqueous
phosphoric acid solution, from which it was recovered by extraction
with ether after the addition of sufficient alkali to neutralise the acid.
Under, however, more vigorous conditions, a very small quantity of a
base can be isolated. a-Hydroxy-;8-phenylacetylaniino-a-phenylethane
(5 grams) was dissolved in benzene (50 c.c), and boiled with phosphoric
oxide (30 grams) for five hours. The benzene was then decanted, and
the residue heated for three hours on the water-bath. The product
was dissolved in water, filtered, and, after rendering alkaline with
potassium hydi'oxide, extracted with ether. The ethereal solution
was washed with dilute hydrochloric acid, and this aqueous solution
treated with picric acid.

The picrate so formed crystallises from alcohol in canary-yellow
micro-prisms, melting at 176 — 177°. There is a possibility that this
substance is the picrate of benzyh'soquinoline, which melts at 184°
(corr.) (Decker and Pschorr, Ber., 1904, 37, 3396). The quantity
obtained was, however, very small, and the substance was not further
investigated.

2-Phenyl-5-veratryloxazole, 0<^tpjjH«i?-^!?|]>CH.

w-Benzoylaminoacetylveratrone (1 gram) (Pictet and Gams, Ber.,
1909, 42, 2948) is warmed with concentrated sulphuric acid (5 c.c.)
for five minutes on the water-bath. The solution is cooled, and decom-
posed by the addition of water. The oxazole derivative separates in
colourless crystals, and on recrystallisation from light petroleum,
forms groups of very slender needles, melting at 97°. The substance
is readily soluble in alcohol or benzene, and the solutions show an
intense blue fluorescence. It forms a rather sparingly soluble hydro-
chloride, which dissolves in warm water, and is apparently undissociated
in presence of an excess of water. Thus the introduction of methoxy-
groups has the effect of increasing the strength of oxazole bases :

0-1194 gave 0-3168 CO2 and 0-0577 HgO. C = 72-4; H = 5-4.
CiyHijjOaN requires C = 72-6 ;' H = 5-3 per cent.

wPhenylacetylaminoaceioveratrone,
C6H3(OMe)2-CO-CH2-NH-CO-CH2Ph.

A solution of w-aminoacetoveratrone stannichloride (25 grams) in
hot water (150 c.c.) was cooled and treated with phenylacetyl chloride

ROBINSON: A NEW SYNTHESIS OF OXAZOLE DERIVATIVES. 2173

(25 grams) and an excess of potassium hydroxide. The mixture was
mechanically stirred, and cooled with small pieces of ice. The pale
yellow, crystalline product was collected, and recrystallisedlfrom methyl
alcohol, in which solvent it is sparingly soluble in the cold. Flocculent
masses of needles are first obtained, and these change in course of
time into a powder consisting of stout needles or prisms, melting at
135^:

0-1249 gave 0-3171 CO2 and 0-0687 HoO. C = 69-2; H = 6-l.
^18^19^4^ requires C = 690 ; H = 6-1 per cent.

2-Benzyl-^-veratryloxazole, 0<^[^'^3^J^.^i!^|J>CH.

(o-Phenylacetylaminoacetoveratrone (1 gram) was dissolved in cold
concentrated sulphuric acid (5 c.c). The solution becomes warm, and
at the end of five minutes was diluted with water. The precipitated
oxazole derivative, after collection and crystallisation from light
petroleum, formed colourless needles, melting at 86°. It is fairly
soluble in hot light petroleum, readily so in alcohol or benzene, but
the solutions show no trace of fluorescence :

0-1272 gave 0-3410 CO^ and 0-0703 HgO. C = 73-1 ; H = 6-1.
CjgHj-OgN requires 0 = 73-2 ; H = 5-8 per cent.

2-Benzoyla7nino-5 : ^-dimethoxy-X-hydrindone,

2-Oximino-5 : 6-dimethoxy-l-hydrindone (10 grams) (Perkin and
Robinson, Trans., 1907, 91, 1074) is treated with a solution of
stannous chloride (40 grams) in concentrated hydrochloric acid
(50 c.c). In a short time the temperature rises, and the stanni-
chloride of the base separates out. After three hours, the precipitate
is collected, dissolved in hot water, and the tin removed by means of
hydrogen sulphide. The filtered solution, on evaporation, yields a
crystalline mass of 2-aviino-^ : ^-dimethoxy-l-hydrindone hydrochloride.
On adding platinic chloride to a hot solution of the hydrochloride,
the platinichloride is obtained in beautiful, golden needles :

0-1305 gave 0-0310 Ft. Pt = 23-7.

(CiiHi,03N)2,H2PtClfi requires Pt = 23-8 per cent.

2-Amino-5 : 6-dimethoxy-l-hydrindone hydrochloride (3 grams) was
dissolved in water (50 c.c.) and shaken with benzoyl chloride (10 grams),
the solution being rendered alkaline by the addition of small quantities
of aqueous potassium hydroxide. A colourless, chalky solid separated,

VOL. XCV. 7 D

2174. WADE AND MERRIMAN : THE CORRECTION OF THE

and was collected and washed with alcohol. To effect this it is
necessary to grind the substance with the solvent in a mortar.

The product, when dried on porous porcelain, cements together to a
very hard and brittle cake. It is sparingly soluble in most organic
solvents, and crystallises from benzene, ethyl acetate, or alcohol in
needles melting at 224°:

01251 gave 03175 CO2 and 0-0646 HgO. C = 69-2; H-6-1.
C13H17O4N requires 0 = 69-4; H = 5-5 per cent.

This benzoyl derivative was found to be unchanged by concentrated
sulphuric acid or alcoholic hydrochloric acid, unless the temperature
employed is so great that the substance undergoes profound
decomposition.

The University,
Manchester.

CCXXXIII. — The Correction of the Specific Gravity
I V of Liquids for the Buoyancy of Air.

By John Wade, D.Sc, and Richard William Merriman, B.A.

In the course of an extensive series of specific gravity determinations,
considerable difficulty was experienced in obtaining concordant
results. The error was eventually traced to the correction for
buoyancy of air, for which the customary formula (I) was employed.
In this formula, w, W are the apparent weights of liquid and water
respectively, ^S*, ,, the corrected specific gravity of the liquid at t°jt°,
and p its true density at i° ( = specific gravity at «°/4°).

Correction Formula I.
S,,, = -^ (1 + ^:M2 _ 0-0012).

Investigation of the relative importance of the various sources of
error led to the formulation of some very simple expressions, which
will be found materially to reduce the labour involved in these
troublesome corrections. It is assumed throughout that the pykno-
meter is filled with liquid and water at identical temperatures, either
by means of a thermostat, or by reading the water-content of the
pyknometer, for any temperature at which it may be filled with
liquid, from a curve plotted from water- values at various other
temperatures. The correction for the expansion of glass, which would
otherwise be necessary, is not only troublesome to determine with

SPECIFIC GRAVITY OF LIQUIDS FOR TnE RUOYAXCV OF AIR. 2175

accuracy, but also renders it diilicult to roduco tlio l)Uoyancy correction
to a reasonably simple form.

The expression (I) assumes a mean value for tlie density of air
(0'0012), and is only valid when the pyknometer (or plummet), water,
and liquid are weighed on a day on which the density happens to
have this value. This condition is rarely complied with, and in a
long series of determinations, during which the atmospheric conditions
are constantly changing, enors may be introduced which full within
the limits of experiment.

The density (o-) of air half saturated with moisture is given in the
following table, in which the temperature of the balance room is
assumed to be between 10° and 25°, and the barometric pressure
between 740 and 780 mm. (corr.). For dry air the values are a trifle
greater, for saturated air a trifle less ; the extreme difference in either
direction is less than 0-00001.

Table I.
Wei'jht of 1 c.c. of Air, a, at ordinary Temperatures and Pressures.

Pressure iu niilliuietres.

Temperature.

740.

750.

760.

770.

780.

2.5°

O-OOllK)

0-001 1(52

0-001177

0-001193

0001208

20

0-00I16S

0-001181

0-001199

0 001 21.5

0-001230

l.^i

o-oon90

oooi-20t;

0-0012-22

0-001-238

0-001254

10

0-001 211

0-001z28

0-001211

0 001 -201

0-001278

It will be seen that, \uider ordinary conditions, the value of <j may
vary by nearly 12 per cent. ; the minimum occurs in hot weather
with a low b.arometer, the maximum in cold weather with a high
barometer. The correction obtained by substituting these values for
that in formula (I) may vary from +000032 to +0-00036 for a light
liquid, such as ether {p = 0-72), and from - 000096 to - 0-00105 for a
heavy liquid, such as sulphuric acid (p = 1 "84). Hence, if the fifth
figure of the specific gravity is to have significance, it is necessary to
introduce the true value of o- into the correction.

For this purpose, the following expression, in which the apparent

specific gravity \^D) at t°jt° {^wjW) is substituted for the corrected

density (p) at t° ( = -5'^ 4), will be found more convenient than the first

formula ; the error introduced by the substitution is negligible (p. 2 1 76).

Correction Formula II.

S^,,^ = D (l + ajD - a) = n + a {I - D).

The above formulae are based on the implicit assumption that the
pyknometer, liquid, and water are weighed under identical atmospheric
conditions (footnote, p. 2179), and with this limitation, formula (11^
gives correct results for any value of a-. When, however, as must

7 D 2

2176 WADE AND MERRIMAN : THE CORRECTION OF THE

necessarily happen in a long series of determinations, the liquid and
water are weighed under different conditions, a more comprehensive
formula is required, or a further, and more serious, error may be
inti'oduced.

The full expression for the corrected specific gravity (S,.,) of a
liquid at t°/t°, whether determined by pyknometer or by areometer, is
given by the following formula, in which tv, W are the apparent
weights of the liquid and water at f, J) is the apparent specific
gravity of the liquid at t°lt° { = w/W), B the density of the weights,
and o", cr' the density of the air at the time of weighing the liquid and
water respectively.*

Co7'rectio7i Formula III.
_ w{l+a- {IIP - l/B)} _ l+a- (\/D- l/B)^
'^'°"° - If |i + 0-' (1 - l/B)} ~ ^ 1 + 0-' (1 - l/B)

This formula involves the following assumptions :

(1) That variations in the apparent weight of the empty pykno-
meter are eliminated, or allowed for (see p. 2178).

(2) That in calculating the weight of air displaced by the various
masses, the following differences are negligible :

(a) the difference between the apparent and true weights of

the various masses ;
{b) the difference between the apparent specific gravity of the

liquid (D) at t°/t° and its true density (p) at t°/4:° ;
(c) the temperature variations in the density of the water.
For (a) the error is at most 0"12 per cent, on the correction ; this is
at most ± 0'05 per cent, on the specific gravity, making a maximum
resultant error of ±006 per 100,000. For (b) the error is at most
±0'05 percent, on the specific gravity correction of 0*05 per cent.,
* Let fV^, IF2, W^, be the ai^parent weights of the pyknometer (1) empty, (2)
filled with water, at t°, (3) filled with liquid at t", when the density of the atmosphere
is respectively <r", a', and a. Let Cl^, flo. ^3 ^^ the corresponding true weights ; v,
V the true volume of the pyknometer, empty and full ; p, S, 11 the true densities of
the liquid, water, and weiglit respectively ; and w, W, D as above.
Then a.,= lV^ + <j {V- TF^/B) ;

^2= JF^ + it' (F- JFJB);
ni=lF+(r"{v- JfJb);

^''^ y ^ { JF, + a{V- W^IB) }-{W^ + <t"(v - W,IB)] .

' ''" { W^ + ff'( V- WJB)} - { n\ + a"{v - JFJB)}

Putting V = « + (fls - riiVp ^ v + (Ho - ni)/5,

and assuming that, for the purpose of the correction,

(i) ni, fls, n3= JF^, JF.^, IF,,,
(ii) a" — (r and a'
in the numerator and denominator respectively,

(iii) p = D and 5 = 1,
this expression reduces to formula (III).

specific; gravity of liquids for the buoyancy of AlU. 2177

making a maximum resultant error of ±0-03 per 100,000, For (c) at
25° the error is 0"33 per cent, on the buoyancy correction for the
water; this is +0'11 per cent, on the weight of the water, makiug
the resultant error at most +0*35 per 100,000 on the specific gravity;
at 20° this falls to +0-22, and at 15° to +0-11 per 100,000.

Now the accuracy of a specific gravity determination is practically
limited by temperature, which for ordinary purposes cannot be regu-
lated more closely than 0*01°. For most organic liquids, this cori-e-
sponds very nearly with 000001 in specific gravity; hence errors of
less than 1 in 100,000 may safely be neglected. As the extreme
aggregate error of formula (III), assuming that all individual errors
are at a maximum and in the same direction, is -l-0'4 per 100,000, it
follows that this formula is rigidly accurate for specific gravities
within ordinary range, under ordinary conditions of temperature
regulation. The assumption that the density of water, for the
purpose of the buoyancy correction, is unity, is the only one that
seriously affects even the sixth decimal place.

Introducing extreme values of D and a into formula (III), and
taking the density of the brass weights as 8 "4,* it will be seen that
the variations in the corrected specific gravity are still further within
the limits of experiment. In the case of ether, for example, for which
i) = 0-736 at 0°/0' with o- and o-' = 0-0012, the extreme deviation from
the true correction, namely, when o-^ 0-001 15 and o-' = 0-00125, or vice
versa, is ±0 00008 ; this would correspond with a variation of 0-08^ in
temperature, or, in a 50 c.c. pyknomeier, of 0-004: gram in weight. t

The above formula, although much simpler than the rigid expression
from which it is derived, is still rather cumbrous, and makes correction
decidedly laborious. In a series of determinations, the labour may
be materially lessened by plotting the true water-content of the
pyknometer against temperature once for all, as already indicated.
The weight of water can then be read for any temperature at which
the pyknometer may have been filled with the liquid ; and the trouble-

* Strictly speaking, the density of the weights ouglit to be determined experi-
mentally, and the small weights reduced to brass by the usual calibration in air.
As, however, variations in this constant afl'ect only a small coefficient in the
numerator and denominator of the correction factor by the same very small amount,
their influence on the correction is altogether negligible. In the extreme case of
^ = 8-6, Z' = r84, with o- and a' alternately at opposite extremes, the error does not
reach the sixth decimal place of specific gravities within the above range.

D.

<T.

a'.

Co

•rected sp.

gr

0-73600

0-00115

0-0012.O

0-73624

0-OOlL'O

0-00120

0-73632

0-001 -25

000115

0-736-10

1-S-lOOO

0-00115

0-00125

1 -83887

0-00120

0-00120

1 83899

0-00125

0-00115

J-83911

2178 WADE AND MERRIMAN: THE CORRECTION OF THE

some alternatives of bringing the liquid to a standard temperature,

or of determining the coefficient of expansion of the pyknometer

itself, are avoided. Putting W'= IF {1 +o-'(l - l/B)] for the corrected

weight of water at t°, and D' = w/W' for the apparent specific

gravity, calculated on tlie corrected weight of the water, formula (III)

becomes :

Correction Formula IV.

^o {1 + o- (1/Z>' - \IB)]
Sric = ]y' = ^ + o- - a-D //>.

The values of a required for this formula are given in table I
(p. 2175), and those of rrD'/B in table II (p. 2179). The error intro-
duced by substituting D' for D in the correction is negligible (compare
B and p, p. 2176). In both formulae, however, it is assumed, as already
stated, that variations in the apparent weight of the empty pykno-
meter are eliminated either by counterpoising the vessel permanently
with glass, or by weighing it immediately before filling with liquid
and water respectively (see footnote, p. 2176). If this is not done, the
error passes by difference into the weight of the liquid, and must be
allowed for. The allowance is most conveniently made by subtracting
a small correction (table III) from the true weight of the vessel. As
the apparent weight of a 50 c.c. pyknometer weighing 20 grams may
fluctuate by 0'0006 gram, neglect of this pi-ecaution may, in the case
of a liquid of specific gravity 0-736, cause an error of 0-00002.*

* If a glass counterpoise be employed, it may conveniently consist of a solid slab,
adjusted to the required weight by grinding. It is sometimes st«ted that the
counterpoise should have approximately the same aiea as the tared vessel, in order
that error from hygroscopic moisture may be eliminated. In the authors' experience
this is unnecessary ; the corrected weight of a pyknometer which has been carefully
wiped with a fine cambric cloth, and allowed to attain equilibrium in a fairly dry
atmosphere, such as that of a balance case, is for practical purposes constant.

But while it is permissible to employ a simple glass counterpoise for the pykno-
meter, the use of a sealed counterpart, such as is employed in determining the
densities of gases, leads to a very grave error, which hitherto has apparently escaped
attention. It is true that the sealed vessel eliminates error due to variations in the
density of the air, and thus, at first sight, simplifies formula (III) to :

Stit' = m-<rlB)l{l-a'/B);
but in so doing, it introduces a constant error, which I'ar outweighs any due to
variations in the atmospheric conditions.

This error arises from the impracticability of exhausting the pyknometer at the
time that the weight of the counterpoise is adjusted, as is done as a matter of course
when a counterpoise is made to a gas density flask. It follows that in the automatic
subtraction of the apparent weight of the empty pyknometer from that of the filled
vessel, not only is the weight of the empty vessel subtracted, but also that of the air
it contained at ilic time that the counterpoise was adjusted. Hence this weight,
( V- v)ff", must be added to the aj)parent weights of the liquid and water after these
have been coiTected for the buoyancy of the air on the brass weights,

SPECIFIC GRAVITY OF LIQUIDS FOR THE BUOYANCY OF AIR. 2179

D'.
07
0-8
0-9
10
1-1
1-2

00115.
•000096
•000110
•000123
•000137
•000150
•000164

<r.

0^00120.
0000100
0-000114
0-000129
0-000143
0-000157
0-000171

Table II.
Values of a-D'/S-i.

0-00125.

•0O0104
•000119
•000134
•000149
-000164
•000178

D'.
1-3

V4

r5
1-n

1-7

1-8

0-00115.
0-000178
0-000192
0^000205
0^00021 9
0 •000233
0^000246

0 001 20.

•000186
•000200
000214
•000229
-000243
-000257

0-00125.
0-000194
0-000208
0-000223
0-000239
0-000253
0-000268

Table III.

Difference between True and Ajiparent Weights of Glass Pyknometer

(p = 2-5).

ff =. 0-00115 0-00120 0-00125

Difference in milligrams per gram 0-323 0-337 0^351

The results afforded by the simplified formula (IV) differ from the
standard correction only by a small figure in the sixth decimal place ;
and the calculation, once the water-content of the pyknometer has
been plotted, is merely a matter of adding and subtracting numbers
read from a table. Further simplification is possible, however.
The terms cr{\lB) and (t'{IJJ>) in formula (III), which embody the
correction for the buoyancy of the air on the weights, become identical
when o- = o-', and in such cases, being very small compared with the
whole, disappear.* The divergence from the true correction therefore
depends on the difference between o- and a-', and is, in fact, numerically
equal to D(cr - a-')/Jj = 0-12 D(cr ~ cr'). For the extreme values of o- and
0-' already considered, namely, O'OOllS and 0-00125, this amounts to
+ 1-2 parts per 100,000, a quantity only just within the experimental

As F" - v = wlD = W, formula (III) then bocome.s successively :

_ %o{\-fflB) + (V-v)(T" _ l+a"/D-(T/B
^t'.r - ^(i_ „'iB) + (V-vy -^ 1 + <7" - a' IB '

Introduction of a sealed counterpoise under these conditions therefore, not only fails
to eliminate the correction for the buoyancy of the air on the contents of the pykno-
meter, but actually renders the full correction more complicated. Taking a meau
value of 0 00120 for a", the error introduced by assuming that the factor for the
buoyancy of air on the liquid and water is eliminated ranges from -0-00033 for
sp. gr. 0-736 to -|- 0^00102 for sp. gr. 1^84, or over a slightly wider range if the
correction for buoyancy on the weights be neglected (see, for example, Squibb's
determination of the density of alcohol, J. Anur. Chcm. Soc, 1893, 15, 126).

* Formula (III) then reduces to St';t' = -D(l + <r/Z))/(l-f a-), which, when multiplied
by (l-<r)/(l-(r), becomes Snc = Z> + cr(l-Z'), that is to say, formula (II); the
terms in (r- are insignificant.

2180 CORRECTION OF SPECIFIC GRAVITY OF LIQUIDS.

limits.* When, as is usually the case, the difference between o- and
a-' is not more than 0 '00005, the term 1/B may therefore safely be
dropped from formula (III), giving :

Correction Formula V.

_ w{{ + <r(llD)} _ 1 + <r/D
\vt' - IP (1 + o-') ~ ^ 1 + cr' ■

If now the water-content of the pyknometer be corrected for the
weight of the air displaced by the water when cr' = 0"00120 (neglecting
that displaced by the weights), this last condition is realised for all
ordinary values of a. And if the values thus obtained be plotted
against temperature once for all, the correction of the apparent specific
gravity in a series of determinations is reduced to a simple addition.
Putting W" = Tr( 1 + cr') for the weight of water at i", corrected in this
7nanner,f and D" = w/W" for the corresponding apparent specific
gravity, formula (V) becomes :

Correction Formula VI

w{l + ailjD)]
iifie = pp = /> (1 + o-/Z> ) = Z> + 0-,

or the correction to he added to the apparent specific gravity^ lohen this is
calculated on the weight of water corrected for air displaced by the water
(o-' = 0 00120), is the weight of 1 c.c. of air at the time of weighing the
liquid. Variation in the apparent weight of the pyknometer, if not
eliminated, must be allowed for as above (p. 2178).

The relative accuracy of the above expressions will be gathered from
the following examples, in which identical data for the specific gravity
of alcohol are reduced by the various methods. The apparent weight

D.

(T.

<r'.

Correction. I

)ifference from

0-736

0-00115

0-00125

+ 0-000230

-0-000008

0-00120

0-001 '20

+ 0 000316

(correct)

000125

0-00115

+ 0-000403

+ 0-000008

1-84

0-00115

0 •001*25

-0-001149

-0-000021

0-00120

0-00120

0 001008

(correct)

0-00125

0-00115

-0-000867

+ 0-000021

t For a series of determinations, the corrected water values would be plotted
against temperature once for all, as under formula (IV). If the water-content of
the pyknometer has been determined when tr' is other than 0-0012, as in the
example given below, the whole curve may readily be corrected by means of
a constant from table II (p. 2179), the quantity 0-0012 fV/B being added to the true
weight of water, namely, JV+ Wa' - Wa'jB, in order to reduce it to the required
partially corrected value with tr'^O 00120. As i?=l for water, the value of
((r-0-0012j/Z? from table II is 0-000138 - 0000143. Hence the corrected weight
is /r+ 0-00116 ?r- (0-000138 - 0-000143) ;r = 51 -7200 + 0-0600 + 0000005 X 52 =
51-7803.

PEkKlN : THE COLOURING MATTER OF COTTON FLOWERS. 2181

(w) of the alcohol at 14-98°, with o- = 000123, was 410716 grams, the
weight of the empty pyknometer having been duly corrected. The
apparent water value (If'), 51 "7200 at 14*98°, was read from a curve
which had been plotted uncorrected with o-' = 0-001 16.

Alcohol.

Water.

Ratio.

Correction.

,S' at f/l".

L

41-0716

51-7200

0-794111

X 1-000311

0-794361

n.

41-0716

51-7200

0-794114

+ 0-000253

0-794367

in.

41-0716

51-7200

0-794414

X 1 -000380

0-794416

IV.

41-0716

51-7729*

0-793306

+ 0-001114

0794417

V.

41-0716

51 -7-200

0-794114

X 1 000389

0-794423

VL

41-0716

51-7803*

0-793190

+ 0-001230

0-794420

Full t

41 -1-292*

51-7728*

0-794417

—

0794417

* Corrected va

ue. t Footnote (p. 2176).

Chemical Labokatory,

Gut's Hospital, London, S.E,

CCXXXIV. — The Colouring Matter of Cotton Flowers.
Gossypiuni Herhacenm. Fart II.

By Arthur George Perkin.

Some years ago (Trans., 1899, 75, 825) it was shown that the flowers
of the Indian variety of the cotton plant contained as a glucoside
a hitherto unknown colouring matter, which was called gossypetin,
but a lack of material did not allow of a more than cursory study
of this compound. More recently (this vol., p. 1855), it has been
observed that gossypetin also exists as a glucoside in the flowers of
the Hibiscus sahdariffa, and the results of this later investigation
have indicated that the true formula of this dyestuff is Cj^HjQOg
rather than CjgHjoOg, which was originally proposed for it. There
was evidence that the rather higher analytical figures formerly
obtained arose from a contamination of the gossypetin with a trace
of a similar yellow colouring matter containing a higher percentage
of carbon, and it is considered likely that this may consist of
quercetin. The formula and general reactions of gossypetin suggest
that it is possibly a hexahydroxyflavone isomeric with myricetin
(Trans., 1902, 81, 205), but the study of this substance is certain
to be difficult, because, even could the flowers be procured in
abundance, the amount of gossypetin which they yield is very small.
With the desire of further investigating this compound, some
quantity of Egyptian cotton flowers were obtained through the
kindness of Mr. W. Lawrence Balls, of the Khedival Agricultural
Society of Cairo, and although as a result the original intention of
the work could not be carried out, some interesting new products

2182 PERKIN: THE COLOURING MATTER OF COTTON FLOWERS.

have been obtained. The flowers (coroHas) were gathered from
the ground, where they had fallen a day or two after the flower
had opened out. They all came from one field of Afifi cotton,
which is the main Egyptian variety and resembles all the
other Egyptian kinds in its general habit of growth and in its
flowers, differing only as regards the tint. The flower is golden-
yellow, with a crimson spot at the base of the petal ; this spot is
not, however, so large as it is in many varieties of Gossypiurn
hcrhaceum,, using the word to signify the Asiatic type of cotton
with small, round-lobed leaves. The Egyptian cottons appear,
according to the recent researches of Messrs. Fletcher and Balls,
to be derived from natural crosses of brown Peruvian cottons with
the Sea Island variety.

Experimental.

The flowers were digested with ten times their weight of boiling
alcohol for six hours, and the pale brown extract was evaporated
to a small bulk. The residual liquid deposited, on cooling, an
orange-brown precipitate, which was collected and washed two or
three times with alcohol (the filtrate and washings (A) being
reserved for examination). This product, which, when allowed to
dry, consisted mainly of a semi-crystalline powder, was possessed
of strong tinctorial property, and was of a glucosidal nature. It
dissolved fairly readily in cold water, and this rather unusual
property suggested that it was probably a salt of the dyestuff,
which, on examination, proved to be the case. As the use of acid
for the neutralisation of the comjDound was, in the circumstances,
to be avoided, an aqueous solution of the substance, which had
been freed from insoluble matter by filtration, and from wax by
agitation with ether, was treated with lead acetate, causing the
production of a dull red-coloured precipitate, which was collected,
the filtrate being colourless or nearly so and free from dissolved
glucoside. The precipitate, after being very thoroughly washed
with boiling water, was mixed to a thin cream with water, and
decomposed by means of hydrogen sulphide ; the mixture was then
heated to boiling, and the lead sulphide removed by filtration. The
dull orange-coloured liquid, on being kept in a vacuum, slowly
deposited a mixture of crystals and gelatinous matter, and the
evaporation was continued until nothing further separated. This
product was collected and crystallised two or three times from
water, and then consisted of a yellow, micro-crystalline powder,
melting at 196 — 197°. As further purification in this manner but
little affected the melting point, it was at first considered to be
pure, but subsequent experiment proved that this was far from

GOSSVPIUM HERBACEUM. PART II. 2183

being the case, and that the substance was in reality a mixture. A
recrystallisation from methyl alcohol and water caused the melting
point to rise to 213 — 215°, by a second treatment in this manner
it fused at 231 — 233°, and by two crystallisations from pyridine and
water a further rise to 245 — 246° then occurred. Finally, it was
ascertained that the true melting point of this more sparingly
soluble constituent of the mixture was 247 — 249° (uncorr.).

When deposited from aqueous liquids, this substance contains
water of crystallisation, which is evolved at 100°, but is regained
in contact with moist air for some days. For the purpose of
analysis, a determination of the gain in weight thus experienced
by the dried substance gave the most satisfactory result :

Found, HoO = 10-64; lOSS.

An analysis both of the dried (a) and undried glucoside (6) was
carried out :

Found, (a) C = 54-22; H = 4-76; (b) C = 48-82; H = 5-07.
C.3iH,.oOio requires C-54-31; H = 4-31.
CoiHooOjo.SH.O req\iires 0 = 4865; H = 5-02; HoO = 10-42 per cent.

It consists of small, glistening, bright yellow plates, almost
insoluble in cold and fairly readily soluble in boiling water. Its
alkaline solutions possess a deep yellow tint; with aqueous lead
acetate it gives a bright red precipitate, and with ferric chloride
an olive-green coloration. The high melting point of this glucoside
is remarkable, for such has been unusual in connexion with the
hitherto described members of this special group. A study of its
hydrolysis with mineral acids revealed that it possessed consider-
able stability in this respect, for when a sokition of 0-766 gram
of the substance in 500 c.c. of water was digested at the boiling
point for one and a-half hours with addition of 1 c.c. of sulphuric
acid, on cooling, 0-733 gram of a yellow powder separated, which,
on examination, was found to consist almost entirely of unaltered
glucoside.

In a second experiment, 0-6905 gram of the dried substance,
dissolved in 100 c.c. of hot water, was boiled for fifteen minutes
with addition of 1 c.c. of sulphuric acid, but as hydrolysis did not
even then appear to have occurred, a further 2 c.c. of the acid was
added, and the solution boiled for two hours. During the latter
operation a dull yellow precipitate gradually separated, and this
was collected and dried at 160°:

Found, Cj5Hjo07=: 63-94.

CoiHooOjo requires CisHmOj — 6508 per cent.

Finally, it was observed that the most efficient strength of acid
for the hydrolysis of the glucoside was 4 c.c. of sulphuric acid in

2184 PEKKIN: THE COLOURING MATTER OF COTTON FLOWERS.

100 c.c. of water, and although a slight discoloration of the product
had occurred after a two hovirs' digestion, this was not very material.
An analysis of the air-dried substance by this method gave as
follows :

Found, C,5Hjo07 = 58-05.

CoiHooOio,3HoO requires CY^HjoOj-^ 58-30 per cent.

The product consisted of yellow needles, contaminated with a
trace of a brown impurity, and on account of this it was first
converted into its acetyl derivative, which formed colourless needles,
melting at 191—194°.

The hydrolysis of this compound was carried out by means of
sulphuric acid in the presence of acetic acid, in the manner usually
employed in these investigations (Trans., 1905, 87, 107) :

Found, C = 58-32; H = 3-97; Ci5Hio07 = 58-75.

Ci5H505(C2H30)5 requires C = 58-59; H = 3-91;
"Ci5HioO- = 58-96 per cent.

An analysis of the free colouring matter gave the following
result :

Found, C = 59-43; H = 3-64.

Cj.riHjoO- requires C = 59-60; H = 3-31 per cent.

The examination of the properties of this substance indicated
that it consisted of quercetin, and it was therefore evident that
the compound CojHooOjg is a hitherto unknown glucoside of this
colouring matter. To identify, if possible, the sugar which is
produced by the hydrolysis of this glucoside, the sulphuric acid
present in the aqueous filtrate from the qviercetin was removed by
means of barium carbonate, and the clear liquid evaporated to
dryness. The viscid residue was extracted with alcohol, the
alcoholic solution evaporated, and the now almost colourless product
was treated with phenylhydrazine in the usual manner. An
osazone was thus obtained crystallising in needles, and this was
collected and washed with a little ether. Considerable trouble was
experienced in the complete purification of this substance by
crystallising it either from alcohol or from alcohol and water, a
point which has been referred to by Tutin (Proc, 1907, 23, 250)
as sometimes occurring with phenylglucosazone ; but by the employ-
ment of alcoholic pyridine and water, as recommended by this
author, the substance previously melting at 196 — 198° then fused
and decomposed at 204 — 205°. Owing to the small quantity of the
glucoside which was available, it was not possible to examine the
pure crystalline sugar, but, on the other hand, as a mixture of
the osazone and phenylglucosazone also melted at 204 — 205°, there
is every reason to consider that it consists of dextrose.

GOSSYPIUM HfiRBACEOM. PART ll. 2185

The hydrolysis of this glucoside, for which the name
qnerclnieritrin * is proposed, proceeds therefore according to the
equation :

CoiHooOjo + HoO = CisHioO; + CcHiA-
which requires a yield of 6508 per cent, of quercetin.

When quercinicritrin is added to boiling acetic anhydride, it
slowl}'^ dissolves, and if, after a two hours' digestion at this tem-
perature, the solution is treated with its own volume of alcohol,
colourless crystals of the acetyl derivative gradually separate out.
The product is purified by recrystallisation from a mixture of
alcohol and acetic acid :

Found, C = 55-31; H = 4-69.

CoiHj20jy(C9H30)g requires C = 55'50; H = 4"50 per cent.

Acetylquercivieritrin consists of needles, which melt at 214 — 216°,
and is very sparingly soluble in boiling alcohol.

A determination of the number of acetyl groups which this
substance contains was carried out by the acetic ether method
(Trans., 1905, 87, 107), employing a solution of 3 c.c. of sulphuric
acid in 30 c.c. of alcohol. At the conclusion of the operation, an
examination showed that hydrolysis of the glucoside had also
occurred, and the quercetin, which had been thus produced, was
isolated by treating the residual alcoholic liquid with hot water
and cautiously distilling off the greater portion of the alcohol :

Found, C2H40. = 61-07; Cj5HioO- = 37-76.

C2iHj"20io(C2H30)8 requires C2H402 = 60-00;
CisHjfjOy^ 37*75 per cent.

It was therefore an octa-acetyl derivative.

Althovigh quercimeritrin itself is almost insoluble in cold water,
it has been shown above that it exists in these flowers, in a readily
soluble condition, probably in the form of a salt. An examination
of the residue given by an incineration of this plant product
indicated the presence of a trace of iron, together with a con-
siderable quantity of potassium, so that evidently the compound in
question is mainly the potassium salt of the glucoside. A trace
of copper was also present in the ash, but no importance could be
attached to this point, because the alcoholic extraction of the
flowers was performed in a copper vessel.

If a hot alcoholic solution of quercimeritrin is treated with
potassium acetate, a yellow precipitate of a 'potassium salt at once
separates. As this, when collected, congealed together, it was not
completely freed from the excess of acetate by washing with
alcohol :

* Derived from the • ' Quercimerinsaure " of Hlasiwetz and Pfaundler (Jahresl).,
1864, 569), the existence of which appears to be doubtful.

2l.'^6 PERKIN: THE COLOURING MATtEH OP COTTON FLOWERS.

Found, K = 91.

C21HJ9O12K requires K = 777 jDcr cent.,

but it was evidently a monopotassium compound, analogous to that
which was previously prepared from rutin, a glucoside of quercetin
(Trans., 1899, 75, 439). This quercimeritrin compound was readily
soluble in water, and almost insoluble in alcohol, and may be
identical with the potassium salt of the glucoside which is present
in the flowers.

The fact that quercimeritrin is an extremely stable glucoside is
rendered obvious by a comparison of its behaviour in this respect
with such well-known quercetin glucosides as quercitrin and rutin.
These latter can be readily hydrolysed by digestion for about an
hour with boiling dilute sulphuric acid of the concentration of
1 c.c. in 250 c.c. of water, whereas, as previously shown,
quercimeritrin is best attacked by an acid which is ten times this
strength.

On wool mordanted with aluminium, tin, chromium, and iron,
quercimeritrin gave the following shades :

Aluminium. Tin. Chromium. Iron,

Orange-yellow Bright orange Reddish-brown Olive-brown

and these results were interesting, because, with the exception of the
colour of the iron mordanted pattern, which is of a rather browner
character, these shades closely resemble those which are given by
quercetin * itself when dyed in a similar manner. On the other
hand, they are widely different from the colours thus yielded by
quercitrin and rutin, which have been described in an earlier
communication (Trans., 1902, 81, 480).

It has been previously pointed out (loc. cit.) that quercitrin is
not hydrolysed during the dyeing operation, and it is most
improbable that the more stable quercimeritrin would suffer decom-
position during this process. The fact therefore that very similar
shades are given both by the latter glucoside and quercetin itself is
of importance, in regard to the location of the svigar nucleus.

A study of the dyeing properties of kaempferol and luteolin
(Trans., 1902, 81, 590), employing woollen cloth, has shown that
the colours given by the chromium, aluminium, and tin mordants
are almost identical in each case. On the other hand, the dyeings
produced by quercetin are not only stronger, but much redder than
those characteristic of kaempferol and luteolin, and this result is
evidently the joint effect of the 3'- and 4'-hydroxyl groups and the

* This was to be anticipated, owing to the fact that both this glucoside and
quercetin yield, with lead acetate solution, similarly coloured precipitates.

GOSSVPIUM HERBACElJM. PAUT It.

2187

pyroiie 3-hydroxyl group, contained by tlie former colouring matter.
Again, it has been rendered certain by the location of the methoxy-

OH

OH/ « \0— C<i

"'^'>0H

OH

6 /

OH

CO-C-OH

OH

0— C

II
CO-CH

NOH.

Kaenipferol.

Luteolin.

OH

OH

0—0

V

>0H

CO-C-OH

OH

Quercetin,

group in rliamnetin (quercetin monomethyl ether) (Trans., 1902,
81, 471):

OH

^0— c/ NOH

CH3-O

\ /

CO-C-OH

OH

Rliamnetin.
which dyes similarly to quercetin, that the hydroxy! groups present
in the phloroglucinol nucleus have little or no effect as regards
the shades produced from the latter compound.

There is every reason, therefore, to suppose that quercimeritrin
contains the quercetin hydroxyl groups in the 3'-, 4'-, and 3-positions
intact, and therefore its constitution will be represented by one
of the two following formulae:

OH OH

"\r

C,H,(OH),-0

0— C

\__x

OH

OH

CO-C-OH

0— C

\.

>0H

CeH7(0H),-0

CO-C-OH

OH

(I.) (II.)

The solution of this problem should not be difficult, and experi-
ments on this point will be carried out as soon as the necessary
quantity of the glucoside is available.

The alcoholic filtrate (A) (p. 2182), from which the crude
potassium quercimeritrin had been removed, was treated with water,
the alcohol evaporated, and the solution then agitated with ether

2188 PERKIN: THE COLOURING MATTER OF COTTON FLOWERS.

to remove waxy matter. The addition of lead acetate caused the
formation of a deep red precipitate, which was collected, and the
filtrate (B) placed aside for subsequent examination. When decom-
posed with hydrogen sulphide, this product gave, by the method
above described, a further quantity of quercimeritrin, the identity
of which was confirmed by analysis :

Found, C = 54-00; H = 4-48.

It has been previously shown that the purification of crude
quercimeritrin is a matter of considerable difficulty, indicating that
in this condition other compounds of a similar nature are present
To investigate this point, the combined mother liquors which had
been derived from it were fractionally evaporated, and the deposits
thus obtained were redissolved and submitted to a similar treat-
ment. Eventually a middle fraction was isolated of a gelatinous
nature, and this was allowed to dry, and digested with a little
boiling acetic acid, which caused it to become granular, whereas the
supernatant liquid acquired a rich dichromate colour. It was
collected, again digested with the boiling acid, and, after extraction
with methyl alcohol, repeatedly crystallised from dilute acetic acid.
For analysis it was dried at 160°:

Found, C = 52-50; H = 4-31.

C21H20O13 requires C = 52'50; H = 4"17 per cent.

It consisted of pale orange-yellow needles, melting at about
200 — 202°, very sparingly soluble in absolute alcohol or acetic acid.
With aqueous lead acetate, it gives a deep red precipitate almost
identical in appearance with that produced by quercimeritrin, and
with ferric chloride an olive-green coloration. Alkalis dissolve it
with a deep yellow tint, which becomes greener when the solution
is diluted with water. As there could be no doubt that this
substance was a glucoside, it was digested with boiling dilute
sulphuric acid (1 c.c. in 25 c.c. of water) for two hours. During the
reaction, crystals slowly separated, and after keeping overnight
these were collected and weighed :

Found, Ci5Hio08 = 65-60.

C21H20O13 requires Ci5IIjq08= 66-25 per cent.

This product formed glistening, yellow needles, which dissolved
with a green colour in very dilvite alkali, and appeared to be
gossypetin. To settle this point, an acetyl derivative was prepared ;
this consisted of colourless needles, melting at 226 — 228°, and was
without doubt identical with acetylgossypetin.

The sugar produced by the hydrolysis of this glucoside was
isolated in the usual manner, and an osazone prepared from it.
This was obtained in yellow needles, which, after crystallisation

GOSSYPIUM HERBACEUM. PART II. 2189

from alcoholic pyridine and water, melted at 203 — 205°, and was
most probably phenylglucosazone.

The hydrolysis of (losai/pitriii^ the name wliich is proposed for
this gkicoside, can therefore be represented as follows :
C,,H,oO,, + HoO = Cyji,,0, + C«H,,0,,

As but slightly less than one gram of this compound has as yet
been isolated, it was not possible to investigate its acetyl derivative
or its dyeing projDcrties. Similarly, however, to quercimcritrin, it
appears to be a somewhat stable glucoside, and it is likely that
further experiment will show that the sugar nucleus occupies an
analogous position in both these compounds. That gossypitrin,
like quercimeritrin, also exists in these flowers as a potassium salt
follows from its method of preparation.

The aqueous filtrates and other residues obtained during the
isolation of this latter glucoside yielded, on further treatment, a
gelatinous mixture, from which but a trace of sparingly soluble
substance could be isolated by means of acetic acid. As a further
separation appeared to be very difficult, especially as the quantity
of the material available was small, it was dissolved in water and
hydrolysed by the addition of sulphuric acid (1 c.c. in 25 c.c. of
water), and digestion at the boiling point for two hours. A dull
yellow-coloured precipitate gradually separated, which was collected,
and converted into hydrochloride by means of hydrochloric acid
in the presence of boiling acetic acid, and the semi-solid mass of
red needles, which thus sejDarated, was collected, washed with acetic
acid, and decomposed with water. The product thus purified proved
to be a mixture, the constituents of which were best separated in
the form of their acetyl compounds. By repeated crystallisation,
first from alcoholic acetic acid and subsequently from acetic
anhydride, a small quantity of a very sparingly soluble acetyl
derivative was isolated, which melted at 229 — 230°, and had the
properties of acetylgossypetin. This was hydrolysed by means of
hydrochloric acid, and gave the following result :

Found, Ci5Hio08 = 55-50.

Ci5H40y(C2H30)c requires Cj5Hio08 = 55'78 per cent.

The free colouring matter, as was anticipated, was found to be
gossypetin :

Found, C = 56-71; H = 3-41.

Ci^HjyOg requires C = 56'60; H = 314 per cent.

The more soluble constituent of the acetylated mixture, which
proved to be the main bulk of this product, was obtained in colour-
less needles, melting at 191 — 194°, and consisted of acetylquercetin.
That the original condition of the gossypetin thus prepared from
VOL. XCV. 7 E

2190 PERKIN: THE COLOURING MATTER OF COTTON FLOWERS.

the plant was the glucoside gossypitrin above described seems
probable, but, on the other hand, it cannot be considered that
the qixercetin isolated in such comparatively large amount had been
produced by the hydrolysis of quercimeritrin. That so sparingly
soluble a substance shovild have resisted isolation by the methods
given above is not probable, and this point will be further
investigated.

A study was now made of the aqueous filtrate from the second
lead precipitate, and this, on treatment at the boiling point with
basic lead acetate, gave a small quantity of a bright yellow
precipitate. This was collected, suspended in water, and decom-
posed with hydrogen sulphide, and the mixture filtered hot. The
pale yellowish-brown filtrate slowly deposited gelatinous nodules,
and after several days these were collected and allowed to drain.
This product, in the moist condition, was dissolved in a little boiling
acetic acid, and the crystals, which separated on cooling, were re-
crystallised from dilute acetic acid, from water, and finally from
pyridine and water :

Found, C = 54-09; H = 4-64.

C21H00O12 requires C = 54'31; H = 4*31 per cent.

It consisted of pale yellow needles, melting at 217 — 219°, which
were much less highly coloured than those of qviercimeritrin, and
in this respect somewhat resembled rutin. It is almost insoluble
in cold and but sparingly in boiling water, soluble in alkaline
solutions with a deep yellow tint, but its most interesting property
is the fact that with aqueous lead acetate it gives a bright yellow
precipitate entirely distinct from the deep red deposit which is
produced in this manner from quercimeritrin. Again, this yellow
lead compound is fairly readily dissolved in the moist condition
by hot dilute acetic acid, whereas the c^uercimeritrin lake is much
more stable under this treatment. With dilute alcoholic ferric
chloride, it gives a deep olive-green coloration.

An important distinction between the two glucosides is observed
also by an examination of their behaviour during hydrolysis, for
when isoquercifrin, the name proposed for this new compound, is
submitted to the action of boiling dilute sulphuric acid (1 c.c. in
25 c.c. of water), a crystalline product rapidly separates, and the
reaction is quickly completed. On the other hand, the comparative
stability of quercimeritrin in these circumstances has been previously
discussed.

The following result was given by the hydrolysis of ?'soquercitrin :

Found, Ci..Hio07 = 64-56.

C2iHooOj2 requires CjjHjqOj^ 65-08 per cent.

The prodvict consisted of yellow needles, soluble in dilute alkalis

GOSSYPlUM HERBACEUM. PART II. 21f)l

with a yellow coloration, and on acetylation gave an acetyl com-
pound, which formed colourless needles, and melted at 191 — 194°.
Further experiment indicated that this colouring matter was
quercetin.

The sugar produced during the hydrolysis of this glucoside was
isolated in the usual manner, and converted into osazone. This,
when purified by crystallisation from alcoholic pyridine and water,
consisted of yellow needles, melting at 203 — 205°, which, when
admixed with pure phenylglucosazone, did not affect the fusion
point of the latter, and thus appeared to be identical with it.

The hydrolysis of ?6'oquercitrin proceeds therefore as follows :
CoiHooOio + HoO = Ci,H,o07 + GeH,oO«.

Dyeing experiments with this glucoside, employing mordanted
wool, gave interesting results, because the shades produced were
entirely distinct from those given by quercimeritrin, but, on the
other hand, somewhat closely resembled those yielded by quercitrin,
although slightly paler (Trans., 1902, 81, 480) :

Clnoniiun:. Alununiiim. Tin. Iron.

Browni.sh-yellow Golden-yellow Lemon-yellow I'rownisli-olive

It is quite evident, therefore, that although quercimeritrin and
Moquercitrin are isomeric, and when hydrolysed give identical
products, they are distinct substances. For reasons previously
discussed, and alluded to elsewhere (Trans., 1902, 81, 210), it is
clear that the sugar group in the latter glucoside is not attached
to the phloroglucinol nucleus, but is probably constituted like
quercitrin, which on hydrolysis yields, however, rhamnose. Three
formulae are possible for t'soquercitrin, which may be briefly
expressed by the statement that the position of the sugar residue
in respect to the quercetin group is at one or other of the points
in the followinor formula which are marked with an asterisk :

OH

uH

Further experiments with regard to isoquercitrin have not been
at present possible, for the total amount as yet obtained has been
merely one gram, but it has been ascertained that its acetyl
derivative is much more soluble in alcohol than the quercimeritrin
compound. In the hope of isolating a larger amount of this
substance, an extract of the flowers, to which a small quantity
of acetic acid had been added, was treated with lead acetate, and
the precipitate removed, but the quantity of isoquercitrin present
in the filtrate did not appear to be thereby increased.

7 E 2

2192 PRRKllV: THE COLOURING MATTER OF COTTON FLOWERS.

The mother liquors obtained during the purification of this
glucoside yielded nothing but quercetin (Found, C = 59'45;
H = 3"49), and this result was further corroborated by the pre-
paration of its acetyl derivative (Found, C = 58*21; H = 4"22),
which melted at 191—194°.

General Fi'operties of the Flowers.

The results of this investigation have shown that Egyptian cotton
flowers contain three hitherto unknown glucosides, quercimeritrin,
jsoquercitrin, and gossypitrin, of which the first-named has been
isolated in by far the largest amount.

To ascertain approximately the total amount of yellow colouring
matter which could be produced from this sample of flowers, 100
grams of the material were exhausted with boiling water, and the
glucosides present in this solution hydrolysed by means of acid.
The mixture was then repeatedly extracted with ether, the ethereal
solution evajDorated, and the residue collected and washed with
water. There was thus obtained 1'86 grams, or TSG per cent, of
the crude colouring matter, consisting of a mixture of quercetin
and gossypetin, and this, when acetylated and the product frac-
tionally crystallised from a mixture of alcohol and acetic acid, gave
0"3 gram of pvire acetylgossypetin (Found, C = 56'68; H = 4'30),
which corresponds with 0'165 gram of gossypetin itself. Such a
process of separation is, however, far from exact, but it seemed
evident that not more than 10 per cent, of the total coloviring
matter consisted of gossypetin. Dyeing experiments carried out
with the flowers themselves in the usual way gave shades which,
although duller, were somewhat similar in character to those
yielded by quercimeritrin, a resvilt indicating that no great quantity
of ?.soquercitrin could be present :

Chromium. Aluminium. Tin. Iron.

Reddisli-brown Green-yellow Orange-brown Olive-brown

In comparison with the colours similarly produced from other
natural dyes, these shades most nearly resemble those of the so-called
"Patent Bai'k," a preparation of quercitron bark, in which quercetin
and no quercitrin is present. Further experiment indicated that
in colouring power two parts of the bark were about equal in
strength to five parts of the flowers, and this result was to be
anticipated, for it was ascertained some time ago that the former
dyestuff contains on the average 5 jaer cent, of quercetin.

The fact that quercetin is the predominating colouring matter of
the Egyptian cotton flowers suggests that in this respect it may
diilcr from the Indian variety, which was first examined, for in

SYNTHESIS OF HORDENINE, THE ALKALOID FROM BARLEY. 2193

the latter case (Joe. cit.) the presence of gossypetin only was
detected. It has, however, been shown in this present work that
the main constituent of the Egyptian material, quercimeritrin, is
not readily susceptible to hydrolysis by acid, and it is possible that
under the former experimental conditions the main bulk of this
glucoside, if present, escaped decomposition. Through the kindness
of Mr. I. H. Burkill, Reporter on Economic Products to the
Government of India, a considerable quantity of the Indian
material will be shortly available for investigation, and an oppor-
tunity will arise, not only for a study of the constitution of gossy-
petin, but for a direct comparison of the two varieties of flower, a
matter which appears to be of considerable interest.

Cloth WORK EKs' Reskaf.ch Labor atoky,
The Univeksity,
Leeds.

CCXXXV. — Spithi'sis of Horde nine, the Alkaloid from

Barley.

By George Bakgek.

A FEW years ago Leger (Co})i])f. rend., 1906, 142, 108) isolated
from barley germs a crystalline alkaloid, which he named hordenine,
and subsequently {fJowpt. rend., 1906, 143, 234, 916) gave the
following constitution :

OH^ \CH2-CH2-N(CH3)2.

This constitutional formula was confirmed by Gaebel (Arch.
Pliarm., 1906, 244, 435), and the physiological action of hordenine
was studied by Camus {ArcJi. int. de riiannacodijn. ct de Ther.,
1906, 16, 43).

It is evident that hordenine (^^hydroxyphenylethyldimethyl-
amine : a-dimethylamino-^-2>hydroxyiDhenylethane) is closely related
to ^'-^lydroxyphenylethylamine, a physiologically active base of
somewhat wide distribution, and the author's recent synthesis of
the latter base (this vol., p. 1123) suggested an attempt to prepare
hordenine from it by methylation.

This attempt was not wholly successful, for although the
methiodide of hordenine was readily obtained by treating 2>hydroxy-
phenylethylaniine with methyl iodide, it was found impossible to
isolate the alkaloid itself; the reaction did not stop at the tertiary
base, but resulted in the formation of the quaternary iodide, no

2194 BAUGEll : SYNTHESIS OF HORDENINE,

matter what proportion of methyl iodide was employed. For tlie
same reason it was found impossible to prepare a-dimetliylamino-
)8-plienylethane, CeHj'CHo-CHo'NMeo, by direct methylation of the
corresponding primary amine, for the only products formed were
the primary and quaternary iodides. The same difficulty was
recently encountered by Johnson and Guest (Amer. Chem. J., 1909,
42, 340).*

A suitable material for the synthesis of hordeninc was, however,
found in phcnylethyl alcohol (benzylcarbinol), a commercial
pi'oduct, from which a-chloro-^-phenylethane could be prepared.
The latter substance yielded, with dimethylamine, the desired
o-dimethylamino-i8-phenylethane. After nitration of this tertiary
base, the j;-nitro-compound was isolated as the oxalate. It was also
found possible to obtain pure a-chloro-^S-jj-nitrophenylethane by
distillation and crystallisation, and then to combine it with di-
methylamine. On reduction the separation of the amino-compound
from the unchanged nitro-compound proved difficult, since both
substances are bases ; the crude reaction-product was therefore
diazotised, and finally yielded a small quantity of a base, identical
with hordenine, prepared from malt germs.

Experimental.
a-Chloro-^-jihenyhthanc, CcH^-CHg-CHgCl.

Fischer and Schmitz have shown {Ber., 1906, 39, 2208) that,
contrary to the statement of Fittig and Kiesow (Annalen, 1870,
156, 245), the principal product of the chlorination of ethyl-
benzene is the a- and not the /3-compound. They therefore used
instead a-bromo-)3-phenylethane, C^.H-'CHo'CH^Br, which may be
prepared according to Grignard's method {Cumjjt. rend., 1904, 138,
1049). This method is, however, not very simple, and the required
compound may be obtained more readily from phenylethyl alcohol
(benzylcarbinol) (a commercial product, which is prepared syn-
thetically, because it occurs in rose-oil).

By heating this alcohol with hydrogen chloride, only a small
yield of the desired compound was obtainable; thionyl chloride and
phosphorus pentachloride furnished a larger proportion, but the

* The phenylethylmetbylamine prepared by these authors has been obtained in
the course of the jiresent work by reduction of the condensation product of phenyl -
acetaldehyde with methylaniine, C6H5*CH2*CH:NMe. It is, of course, also readily
obtainable from a-chloro-/3-phenylethane and methylamine in the manner described
below for the preparation of tlie dimethyl derivative ; its ;9-nitro-derivativc was
prepared from o-chloro-fl-;i;-nitrophenylethane and metliylamine. A number of
closely related bases contiining one or two phenolic hydroxyl groups will soon be
described.

THE ALKALOID FROM BARLEY. 2105

product was contaminated with sulphur and phosphorus com-
pounds. The best yield was obtained with phosphorus penta-
chloride as follows.

Dry chloroform ("100 c.c.) was poured on phosphorus pcnta-
chloride (4 1*7 grams), and phenylethyl alcohol (24 '4 grams = one
molecular proportion) was added drop by drop. Much hydrogen
chloride was evolved, and the phosphorus pentachloride gradually
passed into solution ; the reaction was completed by warming on
the water-bath for two hours. After removal of the chloroform
and phosphoryl chloride, the residue distilled under atmospheric
pressure at 190 — 200° with slight decomposition. On redistillation
under 20 mm. pressure, the bulk of the product boiled at 91 — 92°,
and was approximately pure (yield = 70 per cent.):

0-2611 gave 0-2732 AgCl. Cl = 25-8.

CsHqCI requires CI = 25-2 per cent.

a-Diynethylainino-fi-'phenyle.thane, C(;H5*CH2*CHo*N(CH3)2.

Three grams of the above chloride were heated in a sealed tube
with 4 c.c. (a considerable excess) of a 33 per cent, alcoholic solution
of dimethylamine to 100° for several hours, and yielded 2-5 grams
of the base, boiling at 198 — 202°. As so little was available, this
substance was not further characterised, but the whole was nitrated.

a-Diwethylamino-^-'^-nitro'phenylethane,
N02-C6H4-CHo-CH2'N(CH3)o.

2-5 Grams of the compound just described were added drop by
drop to 10 c.c. of nitric acid (D 1-5), cooled to —10°. On diluting
with ice, rendering alkaline, and extracting with ether, a syrupy
mixture of nitro-derivatives was obtained. By adding an ethereal
solution of anhydrous oxalic acid to the syrup, dissolved in ether,
an oxalate was precipitated, which, after repeated crystallisation
from 95 per cent, alcohol, formed elongated leaflets, melting at
153 — 154°. This salt is very sparingly sglvible in hot absolute
alcohol, but dissolves readily in dilute alcohol. The yield was
60 per cent. :

0-2130 gave 0-3989 COo and 01094 HoO. C = 51-0; H-5-7.
CjQHj^OgNo.CgHgO^ requires C = 50'7; H = 5-6 per cent.

That the nitro-group is in the para-position follows from the
conversion of the substance into hordenine. The same salt was
obtained from a-chloro-/3-/;-nitrophenylethane and dimethylamine, as
follows.

2196 BARQER: SYNTHESIS OF HORDENINE,

a-C/iIoro-fi-l>?ii(ropkeni/letJianc, NOo-CeH^-CHa'CHoCl.

a-Cliloro-)8-plienylethane (13 grams) was dropped into nitric acid'
(50 c.c. ; D I'o), cooled by a freezing mixture. After pouring oni
snow, extracting with ether, and washing the ethereal solution withi
sodium carbonate, the residue was distilled under 18 mm. pressure.
Two fractions, b. p. 165 — 175° and 175 — 179°, were collected; the
second of these crystallised almost completely on cooling below 0°,
and was then drained on a porous tile in the cold room. After
recrystallisation from light petroleum, 3" 9 grams of glassy crystals
were obtained, melting sharply at 49° :

0-1354 gave 9-2 c.c. No (moist) at 17° and 758 mm. N = 7-9.

0-1593 „ 0-1195 AgCl. Cl = 18-8.

C8H8O2NCI requires N = 7-6; Cl = 191 per cent.

That the crystalline nitro-compound is the 2>compound is a priori
probable ; that this is indeed the case follows from its conversion
into a-dimethylamino-/3-2?-nitrophenylethane, which at once yielded
an oxalate, melting at 153^154°, and identical with that described
above.

Coni'ersKni of a-Diinetlii/lainino-^-^-iiitro'pltenyletliaiie into
Hordenine.

2-7 Grams of a-dimethylamino-J3-2^nitrophenylethane oxalate
were dissolved in 10 c.c. of alcohol ; 2 grams of tinfoil
and 10 c.c. of concentrated hydrochloric acid were added;
after rendering alkaline with excess of sodium hydroxide, and
extraction with ether, 0-55 gram, of the crude amino-compound
was obtained as a syrup. This was dissolved in 5 per cent,
sulphuric acid, and to the boiling solution the calculated quantity
of sodium nitrite was gradually added. Much resin was formed ;
on cooling, the filtered solution was rendered alkaline with sodium
hydroxide, washed with ether, sodium carbonate added, and the
solution extracted with ether. The ethereal extract left, on
evaporation, a small quantity of crystals (m. p. 111°) and a little
resin. On again dissolving the crystals in ether, the phenolic amine
was extracted with sodium hydroxide, and afterwards shaken with
ether; on evaporation of the ether, yellow crystals separated, which
were drained on a porous tile and recrystallised from a mixture of
benzene and light petroleum. In this way a small quantity of a
white, crystalline substance was obtained, melting at 117 — 117-5°.
A specimen of pure natural hordenine melted at 117-5°, and a
mixture of equal quantities of the synthetic and the natural
substance at 117 — 117-5°.

THE ALKALOID FROM BARLEY. 2197

The synthetic specimen gave ^Millon's reaction very intensely;
it reddened pbcnolplithalein, was not coloured by concentrated
sulphuric acid, and reduced acid potassium permanganate in the
cold and ammoniacal silver nitrate on warming; in all these respects
its properties were identical with those of the natural base, as
described by Leger. The amount of the synthetic substance
obtained was insufficient for analysis.

The natural hordenine, used for comparison, was purified by
distillation, the boiling point being 173- — ^174°/11 mm. As in the
case of 2^-hydroxyphcnyletliylaniinc, distillation is by far the most
convenient method of purification.

Preparation of Unrden'mc Methiodide from \)-U ydroxyphenylclhyl-

aminc.

Two grams of 2>hydroxyphenylethylamine were dissolved in a
little methyl alcohol, and boiled for a few minutes with a large
excess (20 c.c.) of methyl iodide. After two days, glassy prisms
separated, which were up to 4 cm. in length; the weight was 0"45
gram, much being left in the mother lic^uor.. On recrystallisation
from water, the quaternary iodide gave stout crystals, melting at
230 — ^231°, and closely resembling natural hordenine methiodide,
a specimen of which melted at 229 — 230°; on mixing the two, the
melting point was 229—230° :

0-1444 gave 0-1110 Agl. 1 = 41-5.

CuHjgONI requires 1 = 41-3 per cent.

Bntzoylh ordenine methiodide,

C,H-/CO-0-CgH4-CHo-CH.2-N(CIT;5),.J,
was prepared from both specimens of hordenine methiodide; in
each case hexagonal leaflets were obtained, sparingly soluble in
hot water, and melting at 252 — ^254° ; this was also the melting
point of the mixture of the synthetic and natural substance.

Although hordenine methiodide can thus be readily prepared
from ^;-hydroxyphenylethylamine, numerous attempts to synthesise
the alkaloid itself by this method were unsuccessful, and the other
method, described above, had to be employed.

AVellcome Physiolooical Research Laboratories,
IIekne Hill, London, S. E.

2198 MITCHELL AND SMITH

CCXXXVI. — Volumetric Estimation oj Sulphates.

By Alec Duncan Mitchell and Clarence Smith.

A KAPiD and accurate method for the volumetric estimation of
suljjhates is a much-needed process. All of these methods depend
on the use of standard barium chloride solutions, but the exact
determination of the end-point is a matter of difficulty. The
method we are about to describe avoids this difficulty, and depends
on the well-known ferricyanide end-point. After some preliminary
work, our attention was called to a paper (^Zeitsch. anal. Ckem.,
1879, 18, 521) in which Precht advocates an essentially similar
method ; but as we encountered difficulties which he appears not to
have noticed, and as he gave no details of his process, we continued
our investigation.

A convenient quantity of a sulphate is taken and dissolved in
water or pure hydrochloric acid, or, if necessary, dilute nitric acid,
and a slight excess of standard (2N j5) solution of barium chloride
is added. The mixture is boiled and rendered neutral by ammonium
hydroxide; sodium acetate, acetic acid, and a slight excess of
i\^/10-amnionium dichromate are added. The mixture is made up
to 100 c.c, and the precipitate allowed to settle; 25 c.c. of the
clear supernatant liquid are titrated with i\''/20-ferrous ammonium
sulphate, using potassium ferricyanide as an external indicator, and
taking the first appearance of a green tinge as the end-point.

Preliminary experiments were made in which it was found that
if ammonium dichromate is added to a solution of barium chloride,
a certain amount of barium chromate remains in solution, owing
to the formation of free mineral acid, but this does not happen
if there is excess of sodium acetate, that is, if the solution is neutral
or acidified by acetic acid.

Precht makes no mention of the fact that barium chromate
dissolves in dilute solutions of strong acids, and does not state that
he used neutral or alkaline solutions. Also he used a standard
solution of potassium chromate, which is much more difficult to
keep than one of the dichromate, being attacked by carbon dioxide.
We found it advisable to use ammonium dichromate, as, apparently,
barium chromate, on being precipitated by potassium dichromate,
carries down with it traces of the potassium salt; the ammonium
salt is much more soluble, and therefore preferable.

In the course of this work we used sulphuric acid (which was
neutralised by ammonium hydroxide and hence was equivalent to
ammoniuna sulphate), sodium sulphate, potassium sulphate, zing

VOLUMETRIC ESTIMATION OF SULPHATES. 2199

sulphate, magnesium sulphate, and copper ammonium sulphate.
With potassium sulphate there is evidence of considerable adsorp-
tion (to the extent of nearly 2 per cent.), but this is minimised by
boiling the precipitate for several hours with a little dilute hydro-
chloric acid (compare Sachcr, Cliem. Zeit., 1909, 33, 941),
neutralising with ammonium hydroxide, and proceeding as before.
Precht does not mention this difficulty, which is always met with
in the gravimetric method also. In the case of sodium sulphate
the adsorption is negligible, but is noticed slightly in the less soluble
double sulphates, such as zinc ammonium sulphate and mag-
nesium ammonium sulphate. The possilnlity of the formation of
a double sulphate of barium and potassium has not been overlooked,
and is rendered more probable from analogy to lead (Fox, this vol.,
p. 878).

This method is of wide application, since most chromates are
soluble in acetic acid, and hence jiresent no difficulty. Some, how-
ever, give a coloration with the potassium ferricyanide which
obscures the end-point ; copper is a case in point, but with a little
practice it is possible to find a well-defined end-point at which a
green tinge affects the predominating brown colour. Excluding
weighings, five determinations can be made in an hour.

In the appended results, larger quantities are used than is usual,
but the method applies for smaller quantities, as shown by the
results obtained over a fair range, of which magnesium sulphate
is given as an example ; but in all cases the strength of the titrating
liquids can be adjusted for convenience. The results recorded below
are not selected ; in each series the five experiments represent five
consecutive determinations. It should be noted that ammonium
dichromate, which is iV'/lO as regards oxidising power, is only N j30
as regards precipitating power.

A few determinations on potassium sulphate were made to find
whether the adsorption was decreased by the use of standard
baryta solution in place of barium chloride ; this gave no better
results.

Results.

I. — Estimation of Ammonium Sulphate {or Sulphuric Acid),
in 2N jb-solution (26'43 grains per litre).

2i\V5-(NH4)2S04

2A75-(NH4)oSO

taken,

2i\75-BaC]2,

i\710-(NH4)oCr.p-,f.A720

-Fe(NH,),(S04)o,

found,

C.f.

c.c.

c.c.

c.c.

c.c.

•JO -10

20-54

4-05

0-88

20-16

19-99

20-26

3-50

095

19-99

20-15

20-68

4-77

0-81

20-15

*2014

20-31

3-17

0-54

19-96

21 -39

21-75

4-05

0-95

21-39

This determination is obviously affected by some accidental error.

2200 MITCHELL AND SMITH:

II. — Ksi'niialioii of Soi/iiim SitlpJiatr, in 2N j'b-sulufion (28-43 (/rams

j)er litre).

2A^/5-NaoS04 2A^/5-Na2S04
taken; 2i\75-BaCl2, NI\0-{'^Y{i).fiuO^, AV^O-FeCNH^ySOj)^, found,

c.c. c.c. c.c. c.c. c.c.

20-04 20-32 3-88 0-64 19-89

•2005 20-17 2-12 0-29 19-91

20-19 20-59 3-98 0-88 20 22

20-12 20-70 6-10 1-09 20-05

20-10 20-56 3-89 0-91 20-22

III,- — Estiniatiun of Zinc Suljfhate, in 2N j ^-solution (57-51 (jrums

of ZnS04,7H20 per litre).

•2N/5-ZnSOi " 2A^/5-ZnS04

taken, 2A75-Bi.Cl2, iV^/lO-lNHJoCrA, A^/20-Fe(NH4)2(SO4), found,

c.c. c.c. c.c. c.c. c.c.

•JO-01 20-20 2-56 0-80 "20-04

20 09 20-51 4-57 1-02 20-09

'2001 20-47 4-96 1-14 20*02

20-02 20-24 3-00 0-71 19-98

2011 20-52 3-88 0-63 20-08

IV. — Estimatioiv of Mat/ziesium Sulphate, in 2N j 5-solutio?i (49-30
grams of MgSO^jTHgO per litre).

2iV^/5-MgS04
N/lO-C^H^lfiT^OT, iV^/20-Fe(NH4)2(SO4)5, found,
c.c. c.c. c.c.

3-01 0-96 20 07

6-70 1-81 19-98

4-40 0-58 20-15

4-89 - 1-26 '20-00

5-89 1-97 19-98

* Bad determination.

The following determinations show that the method is equally
applicable to smaller quantities.

2iV/5-MgS04

A710-(NH4)2Cr2O7, JV/-20 Fe(NH4)2(S04)2, found,

c.c. c.c. c.c.

5-91 1-15 5-07

3-88 0 81 9-74

2-31 0-53 15-14

2-00 0-24 19-83

4-56 0 37 24-97

V. — Estimation of Cojrper Animoniuui Sulphate, in 2N j5-solution
(40-00 (/rams of CuS04,(NH4)oSO4,6H2O per litre).

'AN/!,- 2A/5-

CuS04,(NH4)2S04 ChSO«,(N H4)2S04

taken, 2AV5.BaCl2, iV^/10-(NH4).3Cr2O7, i\720-Fe(NH4)2(SO4).„ found,

c.c. c.c. c.c. c.c. c.c.

20 05 20-44 4 22 1*07 20-09

20-09 20-65 5*15 0'94 '2010

20-00 20-47 6-09 1-75 '20 03

20-13 20-51 4-19 0-85 2010

20-09 20-52 6-71 239 2019

2iV/5-MgS04
taken.

2i\75-BaCl

C.C.

C.C.

'20-11
20-05

*19-95
-20-01
20-05

20-25
20-50
20-69
20-40
'20-31

2A^/5-MgS04
taken.

2iV/5-BaCl2

C.c.

c.c.

5-03

9-70

15-11

19-88

25-00

5-67
10-12
15-35
•20-08
25-61

VOLUMETRIC ESTIMATION OF SULPHATES. 2201

VI. — Estiytiation of Potassmin Sulphate, in 2N /5-solution (34*85

graiitfi jff'f lid'c).

(Boiling for several hours with dilute hydrochloric acid is necessary.)

2A75-K,S04 2A75-K.,S04
taken, 2A75-BaCl2, A^/lO-CNHJjCroO:, W'/-J0-Fe{NH4).,(SO4^„ found,

e.c. c.c. c.c. c.c. CO.

20-1-2 20 -48 5-59 1-50 20-0.'.

20-08 20-27 3-95 1-55 20-13

20-03 'iO-fjS 5-26 lOQ 2001

20-32 20 60 5 36 1-61 20-24

20-17 2067 6-33 1-33 '20 06

That adsorption does take place without these precautions to the
same extent as the discrepancy in the results is shown as follows.
A hot solution of potassium sulphate is precipitated by just sufficient
hot barium acetate solution, and the precipitate is filtered, dried,
boiled with alcohol (to remove potassium acetate), filtered, and
dried. A definite amount of the dry substance is boiled for several
hours with dilute hydrochloric acid and a little sulphuric acid
(which serves the double purpose of keeping the barium suljjhate
insoluble, and of producing the more soluble acid potassium sulphate
from the normal sulphate) ; it is then filtered, washed with a little
cold water, and dried. It is found that the potassium sulphate
thus boiled out constitutes I'ST per cent, of the total precipitate,
or I'SS per cent, of the original potassium sulphate.

East Lonoon College.

OBITUARY NOTICES.

BENNETT HOOPER BROUGH.

Born 1860; Died October 3rd, 1908.

Bennett Hooper Brough was born at Clapliam ; his father, John
Cargill Broiigh, a Fellow of this Society, was for some time editor
of The Chemist and Druggist, subsequently he became librarian
at the London Institute in Finsbury Circus, but after some years
of ill-health he died in 1872. Brough and a younger brother and
sister were left orphans ; bvit their friends, inchiding Michael
Carteighe and William Chandler Roberts (afterwards Sir William
Roberts- Austen), both Fellows of this Society, raised a fund for
the education and maintenance of the children.

Brough was educated at the City of London School, whence he
passed, in 1878, to the Royal School of Mines, and, having
graduated as Associate in 1881, he went to the Royal Prussian
Mining Academy of Clausthal, in the Harz district of Germany,
to complete his technical training. In 1882, when he was twenty-
three, Brough was appointed assistant to Sir Warington Smyth,
Professor of Mining at the Royal School of Mines, and four years
later he instituted at the School a course in mine surveying, which
he continued to direct with conspicuous success until his trans-
ference to the Iron and Steel Institute in 1893, when he took up
the secretaryship of that Institute, a post which he retained until
his death. His connexion with the Iron and Steel Institute had,
however, started ten years before, and during the whole of that
period his technical knowledge, literary skill, and linguistic
capabilities had been exercised as an abstractor of the Journal
of the Institute, and as an assistant and translator in the conduct-
ing of its foreign meetings. These talents were also applied to
the Journal of the Chemical Society, for which Brough acted as
abstractor from 1883 to 1895. Moreover, he served as a Member of
the Council from 1895 to 1898. He was also a past Member of
Council of the Institute of Chemistry and a Fellow of the Geological
Society, and a Member of the Institvition of Mining Engineers, of
the Chartered Institute of Secretaries, and of the International
Association for Testing Materials; in fact, of the three latter he

OBITUARY. 2203

was again a Member of Council. He was likewise an active and
welcome supporter of many foreign mining, metallurgical, and
kindred technical associations.

His great powers of discrimination and discernment, added to
his technical ability and general culture, combined, as they were
in his case, with remarkable tactfulness, led to his services being
sought in many directions; he, however, only accepted such work
that would either assist him at his post or that would not, in any
way, interfere with his work at the Institute, to which he was
rigorously loyal and zealous. We find him serving on the Jury
of several exhibitions, such as the Inventions Exhibition in 1885,
the Paris Exhibitions of 1889 and 1900, the St. Louis Exhibition
in 1904, and at the Franco-British Exhibition in London in 1908.
He had acted as Examiner in Mining to the Board of Education,
and as External Examiner to the Royal School of Mines, as well
as to the Camborne School of Mines, whilst as a lecturer he was
in great requisition throughout the United Kingdom, and occa-
sionally abroad as well. At the International Congress of Applied
Chemistry in Rome, he was selected as one of the Presidents. He
delivered the Cantor Lectures at the Royal Society of Arts on
several occasions; in 1892, on ''Mine Surveying"; in 1900, on
" The Nature and Yield of Metalliferous Deposits " ; in 1903, on
"The Mining of Non-rnetallic Minerals "; and in 1906 he delivered
a course of juvenile lectures, at the Society, on " Perils and
Adventures Underground." He was awarded the Society's Silver
Medal for his paper on " Mining at Great Depths."

To technical literature, he was a prolific and valued contributor.
In fact, in this direction his fine store of knowledge, his retentive
memory, and a facile pen stood him in good stead. Among his
numerous contributions may be cited " A Treatise on Mine Survey-
ing," which appeared first in 1888, and has now reached the
thirteenth edition. He contributed the articles on " Mining " to
Chambers's Encyclo'pcedia; the article on " Euel " to Thorpe's
Dictionary of Applied Chemistri/ ; and many of his communications
may be fovmd in the Journal of the Iron and, Steel Institute, in the
Transactions of the Institution of Mining Engineers, as well as in
other publications.

Brough had many social qualities, which endeared him to a large
circle of friends. He was a staunch friend, ever ready to help
those who sought his advice, and in case of the breakdown of a
comrade he would, with characteristic readiness, energy, and whole-
heartedness, either single-handed or in co-operation with others,
at once put into action a scheme of relief, and would not rest
until his object had been achieved. He had a subtle, mellow

2204 OBITUARY.

vein of humour, tinged with a kindly cynicism; he was often
tempted to use these attributes in his writings and lectures, but
he generally reserved them for private life and after-dinner
speeches, in which he excelled. He was a capital host, with excep-
tional gifts as a raconteur, an accomplishment he occasionally
exercised in many languages, to the astonishment of those who had
met him for the first time.

In 1895 he married Barbara, daughter of Edward Lloyd,
barrister-at-law, whom he has left with two yovmg children, a boy
and a girl.

Brough was suddenly seized with acute gastric pains on October
1st, 1908, at Middlesbrough, during one of those successful meetings
of the Iron and Steel Institute which became a feature of his
tenure of the office of Secretary to that Institute. His illness
necessitated immediate removal to a nursing home at Newcastle-
upon-Tyne, where he succumbed to the exhaustion following an
operation, on October 3rd, 1908.

Brough's death has caused a blank which is not easily filled.
Many are they who miss his genial and stimulating comradeship,
and still more who feel the loss of his ever-ready assistance and
advice.

D. A. Louis.

RICHARD JOHN FRISWELL.
Born February 24th, 1849; Died February 6th, 1908.

Richard John Friswell, who was born in London, was the eldest
son of James Hain Friswell, a well-known essayist and novelist,
perhaps best remembered now as the author of '" The Gentle Life."
His mother was an artist and a frequent exhibitor at the Royal
Academy.

He was educated at private schools in London and near
Southampton. As a possible outlet for the disposition he showed
towards science, mox'e especially chemistry, he was, on leaving
school, at first placed as an articled pupil with a well-known
photographer, Mr. Valentine Blanchard; but photography as a
profession did not appeal to him, and he attended evening classes
at King's College in chemistry and other subjects; finally he was
allowed to follow his inclinations, and he went as a student to the
Royal College of Chemistry. On completing his studies there,
under Prof. Frankland and William Valentin, he became assistant
to Dr. W. J. Russell, then Professor of Chemistry, at St. Mary's
Hospital.

OBITUARY. 2205

In 1871 Friswell took part in the Indian eclipse expedition,
under Mr. (now Sir Joseph) Norman Lockyer. Successful as the
expedition was, the day of the eclipse was for Friswell one of bitter
disappointment. He was placed at Manantoddy, in charge of the
analysing spectroscope. " Unfortunately," to quote Lockyer's
words, " to the regret of all, Mr. Abbay and Mr. Friswell, who
were among the best prepared for doing good work, and were at a
station at which everybody said cloudless we^ather was certain, found
themselves in a storm of cloud and mist which obscured the sun."
Later he was again asked to take part in another eclipse expedi-
tion, that to the Andaman Islands in 1875, but he was not then
able to leave London.

As a result of the co-operation in the 1871 expedition, Friswell,
in August, 1872, became research assistant to Norman Lockyer,
with -whom he remained for the next two years. Under Lockyer's
direction he assisted in numerous spectroscopic researches, in many
of which his practical knowledge of photography was of much use.
Amongst these may be instanced the first continuous series of
observations on the solar chromosphere attempted in England.

In 1874 he was offered an appointment as research chemist in
the Atlas Aniline Dye Works (Messrs. Brooke, Simp&on and Spiller),
at Hackney Wick, and for many years he took an active part in
carrying on these works. In 1886, when the Atlas Works were
converted into a limited company, he was made a director and
chemical manager of the works; this post he held until 1899, when
he became manager of the works of the British Uralite Company,
at Higham, Kent, where he remained until 1902, when he started
a practice in London as a consulting chemist and chemical engineer.

After his first paper on "A new double salt of Thallium" (this
journal, 1871, 24, 461, and also 1877, 32, 251), Friswell's con-
tributions to science were mainly concerned with the coal-tar colour
industry; amongst these may be mentioned "On the relation of
Diazobenzene to Amidoazobenzene " (Trans., 1885, 47, 917, and
also Proc, 1887, 3, 26) and " The Constitution of Diazobenzene-
anilide and its relation to Amidoazobenzene " (Trans., 1886, 49,
746), both papers being published in collaboration with Prof. A. G.
Green; "The Properties of Nitrobenzene" (Trans., 1897, 71,
1010) ; " The Preparation of para-Toluidine from mixed Toluidines
by means of para-Toluidine hydrate " (/. Soc. Chem. Ind., 1908,
27, 258).

Friswell served t\vice on the Council of the Chemical Society.
He was an original member of the Society of Chemical Industry,
and was chairman of its London Section from 1906 to the time of
his death.

VOL. XCV. 7 F

220G OBITUARY.

lie was actively concerned in the inception of the Institute of
Chemistry, and was elected a member of its first Council. Alto-
gether he served fifteen years as member of Council of the Institute.
He was also a Vice-President, 1896-1899, and Censor 1898-1899.
He took an active part in the transfer of the Institute to its
present quarters, and gave great assistance in the designing and
organisation of its laboratories. For many years he acted as
Chairman of the House Committee.

Friswell was Honorary Secretary of the Photographic Society
1874-1876, and Master of the Horners' Company 1894-1895.

Taken ill on the New Year's Eve with pleuro-pneumonia and
enteric fever, he died after five weeks' suffering on February 6th,
1908.

Friswell married, in 1877, Millicent, daughter of W. H. Colling-
ridge, and leaves a family of two sons and three daughters.

He was a man of wide tastes, both literary and artistic; his
genial, enthusiastic, and kindly nature endeared him to all with
whom he came into intimate contact, and on these he exercised a
very wholesome influence.

A. J. G.

WILLIAM ASHWELL SHENSTONE.*

Born December 1st, 1850; Died February 3rd, 1908.

The life of a schoolmaster is usually laborious, and when he devotes
the greater part of his holidays to study and experimental research,
little time is left for incident outside the daily routine. Shenstone's
career was uneventful, but it brought him into frequent contact
with the scientific world, in which he made many lasting friend-
ships.

Born at Colchester on December 1st, 1850, he came of a family
collateral with that of the poet, as it apiDears that his grandfather,
Joseph Shenstone, born at Halesowen between 1790 and 1800, was a
son of a cousin of that writer. W. A. Shenstone's father, James
Burt Byron Shenstone, was established as a pharmacist at
Colchester, and after the usual course of education at the Colchester
Grammar School the son was received into the business. At the
age of twenty he obtained, as the result of competitive examination,
one of the Bell Scholarships, given annually by the Pharmaceutical
Society. After a course of study in the School of that Society

* This notice is reprinted, by permission, from tlie Proceedings of the Royal
Society.

OBITUARY. 2207

he won the Pereira Medal and other prizes. During the time he
was occupied in his father's business a portion of the premises was
burnt down, and Shenstone was exposed to cold and damp, with
the result that a serious illness followed, from the effects of which
he never completely recovered. The injury which resulted was,
in fact, the primary cause of his last illness nearly forty years
later.

After two years spent in the laboratory of the Pharmaceutical
Society, Shenstone accepted an engagement with Dr. W. A. Tilden,
at that time chief science master at Clifton College. Here he
displayed those qualities of patience, diligence, accuracy, and
enthusiastic devotion to experimental work which distinguished
him throughout life. In 1874 work was begun on the terpenes, at
that time an unexplored department of organic chemistry, and
Shenstone joined in the investigation with his usual ardour. The
result was a paper, under the joint names of Tilden and Shenstone,
published in the " Transactions of the Chemical Society," in which
it was shown that the numerous hydrocarbons of this family then
known were reducible to three classes according to the character
of their nitroso-derivatives.

From Clifton, in 1875, Shenstone passed to the Science Master-
ship at Taunton School, then under the Head Mastership of the
Rev. William Tuckwell. After about two years he moved to a
similar position at Exeter School. Here he built and fitted up a
school laboratory (described in Nature, July 26th, 1878) which
attracted some attention, as it served to show that the practical
teaching of physics and chemistry was within the reach of all
properly conducted schools, and need not be avoided on the ground
of expense, as had been up to that time so frequently alleged.

Shenstone was always an attractive lecturer, and interested
himself much in educational problems, especially in connexion
with the improvement of methods for teaching physical science.
When, in 1880, he succeeded Dr. Tilden as Science Master at
Clifton, he found a field in which he could bring into operation
some of his ideas. Here he was one of the first science masters
to associate practical work with all theoretical teaching, and here
he made use of a modified " heuristic " system, in which an attempt
is made to stimulate the disposition to inquiry which is inherent
in most young minds. The extent to which this system in the
hands of a competent teacher can achieve success is to some extent
indicated by the very wide circulation of Shenstone's two books
{Practical Introduction to Chemistry), and there can be no doubt
that this pioneering work has materially influenced the teaching
of natural science throughout the kingdom.

7 F 2

2208 OBITUARY.

The greater part of his leisure was devoted to original research.
During the earlier part of his time at Clifton he managed to carry
out a difficult piece of work on ozone, and on the properties of
certain highly purified substances, from which he drew important
conclusions. The results of these experiments led him to the
conclusion that chlorine, bromine, and iodine, when in the highest
known condition of purity, and dried by contact under special
conditions with phosphoric oxide for six months or more, do at
once combine with mercury when brought into contact with that
metal similarl}' pvirified and dried. The remarkable indifference
displayed by some substances, when completely deprived of moisture,
to the ordinary conditions of chemical change, had led some
chemists to believe that it is impossible for any two substances to
interact chemically except in the presence of a third substance,
usually water, although only in minute quantity. The question
must be regarded as still open, but it will be difficult for any future
experimenter to improve on Shenstone's method or his manipulative
skill.

Shenstone also joined Professor Tilden in a research on the
" Solubility of Salts in Water at High Temperatures," the results
of which form the subject of a paper in the Philosophical Trans-
actions for 1884. In most of this work a good deal of complicated
glass apparatus was required, and the whole of that which was
needed in his work on ozone, on the purification of chlorine, etc.,
was constructed with his own hands. Shenstone was an accom-
plished glass blower, and in 1886 he published a small book, the
first of its kind, giving instructions suitable for laboratory workers,
which was translated into German, and is to be found in most
chemical laboratories. Shenstone also succeeded in the far more
difficult art of manipulating vitrified quartz, the properties of
which he demonstrated in a lecture at the Royal Institution in
1901. Apparatus constructed of this material is of the utmost
value in certain chemical and physical operations owing to the
fact that it is unaffected by nearly all chemical agents except
hydrofluoric acid, and that its coefficient of dilatation by heat is
practically nil. Hence, unlike glass, it may be suddenly quenched
in cold water from a red heat without injury. He devoted much
time during the last two or three years of his life to the practical
question of producing this material on a manufacturing scale, so
as to bring it within the reach of scientific workers at a moderate
cost, and to these efforts the physicists and chemists of to-day owe
the beautiful clear variety of silica vessels now commonly in use.

Shenstone was elected into the Royal Society in 1898. In his
later years he devoted some time to literary work, and produced

OBITUARY. 2209

ca Life of TAehig (Cassell and Co.), and the year before He died
he gathered into one volume, under the title, The New Physics and
Chemistnj, a series of essays contributed to the Cornhill Magazine,
in which he presented a remarkable and, on the whole, successful
attempt to explain in popular language the modern views of
physicists and chemists on subjects such as matter, motion, the
ether, the nature of atoms and molecules, radioactivity, etc.

He married, in 1883, Mildred, daughter of the late Rev. Reginald
Durrant, and he leaves a widow with a son and a daughter.

Shenstone possessed a fortunate combination of enthusiasm with
peculiar skill in handling apparatus, and under more favourable
conditions would certainly have done a much larger amount of
scientific work. But what he did accomplish was a marvel to
those who knew him well. In spite of the lameness, the cause of
which has already been referred to, and which sometimes led to
general disturbance of health, the brave, bright spirit, which
endeared him to his friends, helped him over mountains of routine
work, and kept him ever eager for the more attractive fields of
science. He died at Mullion, Cornwall, on February 3rd, 1908, and
is buried in the village churchyard.

W. A. T.

EDWARD SONSTADT.
Born November 25th, 1829; Died July 5th, 1908.

Edward Sonstadt, to whom metallurgy is indebted for the first
successful production of the metal magnesium on a manufacturing
scale, was born at Halesworth, in Suffolk, on November 25th, 1829.
His father, Samuel Sonstadt, was a gentleman of private means,

I fond of reading and of studious tastes, but of feeble health and
of nomadic habits, rarely living long in any one place. Owing to
the failure of an American bank he lost the greater part of his
fortune — about £40,000 — and, emigrating to South Africa, died
there in 1845. Young Sonstadt thus found himself at the age of
sixteen in very straitened circumstances, and with a younger sister
dependent upon him. To add to his anxieties, he was, at the
time of his father's death, in poor health, enfeebled by long illness
following upon an attack of brain fever. Indeed, all that he prac-
tically inherited from his father was a frail constitution and
precarious health. Partly for this reason, and partly on account
of the wandering life of the family, he received no regular or
continuous schooling. Indeed, such was his physical condition

2210 OBITUARY.

Avhen a boy that it was never expected that he would reach
manhood.

After his father's death Edward Sonstadt found his way back to
England. Settling his scanty share of their joint inheritance upon
his sister, the poor, frail, diffident youth now set himself to face
the world with such courage as he possessed. And Sonstadt never
lacked courage or self-reliance. He seems to have obtained employ-
ment for a time in a j^rinting office, and to have tried his hand
at book-keeping, and eventually at journalism. When eighteen
years of age he migrated to Canada, where he procvired a situation
as proof-reader in the printing office of the Government Official
Journal. Four years later he returned to England, recalled by
his sister's illness. He remained in London for some years, picking
up a precarious livelihood by his pen. At this period he was a
frequent contributor to Welldo?i's Scientific Register. It was this
connexion with scientific journalism which seems to have first
induced him to turn his attention to chemistry, and he now devoted
all his spare time to the study of that science. He then moved
to Nottingham, where he acquired a small printing and book-
selling business, and acted as librarian at some library in the town.
Here he married Mary Lees, and shortly afterwards, when thirty-
four years of age, removed to Manchester to work a patent he
had secured for the manufacture of metallic magnesium. This
metal, the existence of which Avas signalised by Davy, shortly after
the discovery of the metals of the alkalis, was first definitely
obtained by Bussy about 1829 by the action of potassium upon
anhydrous magnesium chloride. Subsequently Bunsen prepared it
by the electrolysis of the fused salt. Matthiessen, under Bunsen's
direction, greatly improved the electrolytic method by substituting
a mixture of the chlorides of magnesium and potassium for the
anhydrous chloride, which is difficult to procure free from admixed
oxide. He thus obtained considerable quantities of the metal, and
was able to describe its leading properties.

At Deville's instigation Caron sought to place the manufacture
of magnesium upon a commercial basis, but with no great success.
Caron's process, which consisted in heating a mixture of magnesium
chloride and fluorspar with metallic sodium, was costly to work,
the yield was sinall, and the metal far from pure. Sonstadt
greatly cheapened the process by the employment of carnallite —
then available owing to the opening up of the Stassfurt deposits,
and he devised a means of purifying the metal by distilling it.
The fact that magnesium could be readily distilled was known to
Deville and Caron, but Sonstadt was the first to employ this
method of purification on a manufacturing scale. The process

OBITUARY. 2211

was worked out in 1863 by Sonstadt in conjunction with the late
Samuel Mellor, the founder of the Magnesium Metal Company, at
Patricroft, near Manchester. It was at this period that the writer
of this notice first made Sonstadt's acquaintance. He was a
frequent visitor to the chemical laboratory of the Owens College,
then in Quay Street, Manchester, the head of which, the present
Sir Henry Roscoe, took great interest in the development of the
new metallurgical industry, and, indeed, made it the sul)ject of a
Friday evening discourse at the Royal Institution. The writer
well remembers assisting at the preparation of the experi-
mental part of this lecture, and also making such analytical
examinations as were required of the materials and products
of the various stages of the process. The fact that the
light of burning magnesium was highly actinic, and re-
acted powerfully upon sensitive silver salts, had been indicated
by Bunsen and Roscoe, and Sir Henry Roscoe during his lecture
demonstrated this property by actually taking a photograph
of Faraday, who presided on the occasion. This, of course, was
in the wet collodion days, when actinometers were xmknown,
and it was necessary to rehearse the demonstration with some
care in order to determine the conditions of success. The late
Prof. Schorlemmer and the writer were the first to submit them-
selves to the ordeal of being thus photographed, and Sonstadt, who
was present, and who was greatly excited by the experiments, was
the second, and his delight at its success was unbounded. He was at
this time about thirty-five years of age : a frail, spare, thin-featured,
highly-strung, sensitive man, with long flaxen hair, almost womanly
in feature, save for the flowing beard and thin, wispy moustache.

In 1865 Sonstadt, whose health was at all times uncertain and
precarious, and who, like the poet Cowley, was fond of a small
house and a large garden, took up his residence at Port Levague,
near Ramsey, in the Isle of Man. Here he fitted up a laboratory,
and interested himself in the extraction of iodine from sea-water
through the medium of kelp. At that time the iodine industry in
North Britain, more particularly in the vicinity of Glasgow, was of
considerable and of growing importance. It was, however, a highly
speculative business, the price of iodine being subject to violent
fluctuations, owing to market operations. Covirtois, the discoverer
of iodine, was ruined in the attempt to manufacture it, and died
in poverty. Its commercial production in Great Britain was first
tried by Dr. Ure, of Dictionary fame, and in 1845-46, tempted
by the high price — Sis. a pound — which then ruled, there were
as many as twenty makers in Glasgow. In 1863 the price had
temporarily fallen to 5s. a pound, and the manufacture was prac-

2212 OBITUARY.

tically a monopoly, only two firms being engaged in it. At that
time its method of production had been largely revolutionised by
the late Mr. E. C. C. Stanford, who greatly improved the methods
of collecting and treating the weed, so as to obviate in large
measure the fluctuations in quality and yield arising from the
uncertain climate of Scotland. The amount of kelp brought into
the Clyde had risen from about 8000 tons in 1860 to 14,000 tons
in 1863, with an upward tendency in the price of iodine, which
steadily rose from 5s. per pound in 1863 to 34s. in 1872. Sonstadt
began the manufacture of iodine about 1866, collecting the weed
on the rocky shores stretching from Port Levague to Maughold
Head. Here the conditions were very different from those prevail-
ing in the Hebrides, where the peasantry had been kelp burners
since the middle of the eighteenth century, and from the outset
he met with many difficulties and much discouragement. Many of
these difficulties he overcame, but no sooner was he in a position
to place any considerable quantity of iodine on the market than
the Scotch producers lowered their prices to a point at which
competition became impossible, and the Manx venture, ill-starred
from the beginning, collapsed, and Sonstadt well-nigh shared the
fate of the unfortunate Courtois. With a resolution and self-denial
characteristic of him, he set himself to retrieve the fallen fortunes
of the company, and eventually managed to discharge all his
liabilities and repay those who had participated in his luckless
undertaking. But even if he had succeeded, his success could only,
in the nature of things, have been temporary. As the sequel has
shown, British iodine has been practically superseded by that
obtained from caliche, which is capable of yielding far more than
the world requires or is likely to require. The writer at this period
was a constant visitor to Ramsey, and was personally witness of
this attempt to establish the iodine industry in the island. To
Sonstadt is due the credit of first drawing attention to the fact that
iodine exists in sea-water, not as an iodide as generally supposed,
but as an iodate and probably as calcium iodate; and he well
remembers that fact being demonstrated to him in the little
laboratory of which mention has been made. Sonstadt published
some notes on the subject in the Chemical News for 1872. In the
same year he also pointed ovxt the existence of gold in searwater.
He published further a short paper on the existence of caesium and
rubidium in sea-water and in marine products. He was an
extremely painstaking and accurate worker, thoroughly trustworthy,
and scrupulously careful both in observation and inference.

In 1874 Sonstadt returned to London, and in the following year
became chemist to a firm of chemical brokers, with whom he

OBITUARY. 2213

remained until 1890, when, on the reconstruction of the firm after
the death of one of the partners, he was retired. During his
connexion with the firm he greatly improved the methods of testing
anthracene, and was recognised as an expert on this subject. For
many years he was an outside abstractor for the Patent Office, and
had been promised an inside examinership, but failed in securing
the position owing to the retrospective operation of an age limit.
He was an abstractor for the Society of Chemical Industry from
1893 to the time of his death. For the last fifteen years of his
life he lived very quietly at Cheshunt, latterly in comparatively
comfortable circumstances owing to the unexpected improvement
in certain small investments in which he was interested. He died
in the eightieth year of his age, on July 5th, 1908.

T. E. Thorpe.

THOMAS STEVENSON.
Born April 14th, 1838; Died July 27th, 1908.

Sir Thomas Stevenson, who was the son of Mr. Peter Stevenson,
a well-known landed proprietor and farmer, was born on April
14th, 1838, at Rainton, a village in the North Riding of Yorkshire.
The family was an ancient one in Rainton, the very first entry in the
Tipcliffe Register — the parish in which Rainton is situated — being
the marriage of one of the Stevensons.

Stevenson "was educated at Tipcliffe Grammar School, and
remained there until he was nearly fifteen years of age; this
school was provided with a laboratory, and he here acquired a
rudimentary knowledge of chemistry sufficient to enable him to.
make rough analyses of soils and manures for his father. In
1853, he was sent to London, and continued his studies at
Messrs. Nesbit's Chemical School in Kennington Lane, in the
South of London. Professor Odling, A. H. Allen, of Sheffield, and
Charles Graham were also pupils at this school, Graham being
Stevenson's " chum." In 1855-6 he applied himself to the study
of scientific agriculture on his father's farm, but later on, in 1857,
he finally decided to adopt medicine rather than farming as his
profession, and became a pupil of Mr. John Steel, of Bradford,
with whom he studied for a time. In 1859, however, he left
Bradford to come to the Capital, and here he matriculated at
London University, and entered as a student at the Medical School
of Guy's Hospital, with which in after years he became so

2 214. OBITUARY.

intimately associated. He was a most brilliant and most
successful student, for in 1860 and again in 1862 he was First
Prizeman of his Hosjoital, and in the latter year he obtained
the much-coveted " Treasurer's Gold Medal " in Medicine. In
1861 he took the Scholarship in Chemistry at the First M.B.
Examination at London University, also the second Gold Medal,
and was classed the third place in Physiology. In 1862 he became
a Member of the Royal College of Surgeons and Licentiate of the
Royal College of Physicians, taking the Membership of the latter
in 1864 and the Fellowship in 1871.

The year after he had qualified, that is, in 1863, he commenced
practice at Bradford, but six months afterwards he returned to
London, and in the same year graduated M.B. at the University,
taking the Scholarship in Forensic Medicine, and the third place
on the lists both in Surgery and in Medicine. In 1864 he graduated
M.D. London.

In 1868 he became Medical Officer of Health to St. Pancras,
Middlesex, an appointment which he held until 1878. In 1873
he was appointed Public Analyst, not only for the Borough of
St. Pancras, but also for the Coimties of Surrey and Bedford.

It was in 1872 that he was first asked to undertake analytical
work for the Home Office, but it was not until some ten years
afterwards, in 1882, that he was definitely appointed Senior
Scientific Analyst to that Department. His name subsequently
became associated with most of the great cases in toxicology in
England, and in 1904 the King bestowed on him the honour of
knighthood in recognition of his services to the State in that
capacity.

In connexion with Guy's Hospital, he was appointed Demonstrator
of Chemistry in 1864, and in 1870 Lecturer in Chemistry conjointly
with Dr. Debus, Dr. Odling having retired and gone to Oxford
as Professor of Chemistry there. In 1878 he succeeded Dr. Alfred
Swayne Taylor as Lecturer in Forensic Medicine and Medical
Jurisprudence.

Stevenson was elected a Fellow of the Chemical Society, forty-
five years ago, in 1864, and served four times on the Council, once
as a Vice-President. He was one of the founders of the Institute
of Chemistry, of which he subsequently became President
(1897-1900); he also conducted their first Examination in
Pharmacology and Therapeutics. It was during his Presidency
that the late Lord Brampton (Mr. Justice Hawkins) said of him,
" He is a man who in giving evidence before me has always
convinced me that he was right, and that it was useless to oppose
him. I have admired him for his intelligence and knowledge, and
respect him for his courage, candidness, and truth."

OBITDARY. 2215

Sir Thomas was amongst those who founded the Society of Public
Analysts, and was the first Treasurer of that Society, becoming
President in 1896.

His contributions to chemical literature, which consisted mainly
of i:)apers on toxicology and analytical methods, were published in
Gui/s Hosjntal Reports and The Analyst.

In 1867 he married Miss Agnes Moberly, by whom he had seven
children, namely, two sons and five daughters. Of the two sons,
the younger, Claude, survives him and is in practice as a doctor
at Cambridge; but the elder, his firstborn, was drowned at Whitby
in August, 1895 ; this sad event is very pathetic, as his father had
been instrumental in saving the lives of a number of people (nearly
thirty) by the protracted use of artificial respiration after they
had been brought out of the water insensible. One of the daughters
has greatly distinguished herself in the medical profession, being
M.D.Lond., B.S., and Gold Medallist in Surgery. She is now a
sister in the Oxford Mission at Calciitta.

Stevenson's was a most estimable character, upright and truth-
ful. He was ever kind and courteous, and always ready to help.
Both he and Lady Stevenson were imbued with deep religious
feeling, which was not apparent to those who were only casually
acquainted with them. They both unostentatiously did lasting
philanthropic work in the neighbourhood in which they lived.

The death of Lady Stevenson, which took place in January 17th,
1908, was a blow from which he never recovered, for they were
deeply attached to one another. A great change came over him,
he seemed suddenly to grow old, and, at the age of seventy, passed
away on July 27th, six months after the death of his wife. He
left many friends, who mourn his loss.

C. E. G.

2216 REPORT OF THE INTERNATIONAL

The Council has ordered the following letter and report to be printed
in the Journal and Proceedings of the Society :

Imperial College of Science and TEcnNOLOGY,

South Kensington,

London, S.W.
November 17 th, 1909.
Gentlemen,

I beg to present to the Council of the Chemical Society the
E,eport of the International Committee on Atomic Weights, 1910, to
which I have affixed, as desired by them, the signatures of Professors
Ostwald and Urbain.

Since the Committee last reported, new determinations have been
made of the atomic weights of chlorine, nitrogen, carbon, iodine,
silver, phosphorus, arsenic, chromium, tellurium, mercury, palladium?
krypton, and xenon.

Certain of the numbers obtained, if confirmed, would necessitate
minor alterations in the tables, but as additional determinations are
promised we prefer to make no very great changes until corroborative
evidence is forthcoming. We suggest, however, that the value of Cr
should be 52*0 ; that of As should be changed to 74*96 ; and we adopt
the new values for krypton and xenon.

I am. Gentlemen,

Your obedient Sei'vant,

T. E. THORPE.
The Hon. Secretaries,
The Chemical Society,
Burlington House,
London, W.

Report of the International Committee of Atomic Weights, 1910.

Since the preparation of our last report there has been much
activity in the determination of atomic weights. A binef summary of
the results obtained is as follows :

Chlorine, — A novel comparison of chlorine with oxygen is due to
Guye and FIuss {J. Chim. Phys., 1908, 6, 732). Nitrosyl chloride,
NOCl, was first weighed, and then distilled over silver to absorb
chlorine, then over heated copper to absorb oxygen, and finally over

COMMITTEE OF ATOMIC WEIGHTS, 1910. 2217

metallic calcium, which retained the uitrogeu. The complete analysis
of the chloride was thus eifected. From the direct weightrf of the
oxygen and chlorine, CI = 35 "468.

Nitrogen. — In the investigation just cited, Guye and Fluss give
data which correspond to N = l-i006. Guye and Piutza {Coinpt. rend.,

1908, 147, D25) determined the density of the mixed gases produced
by the decomposition of ammonia, and so measured its composition
by volumo. If H=l"0076, then N=14"014. The authors regard
the determination as having only a significance corroborative of the
lower value for nitrogen.

The ratio AgCl : NH.,C1 :: 100 : 37-3217 has been measured by
Richards, Ivoethner, and Tiede {J. Amer. Chem. Soc, 1909, 31, 6).
Reduced with Ag = 107-881, CI = 35-4574, and H = 1-0076, N = 14-0085.
If H = 1*0078, N = 14-008. The values assigned to silver and chlorine
are derived from former researches by Richards and his colleagues
in the Harvard laboratory.

Carbon. — From the ratio between silver and teti'aethylammonium
bromide, as measured by Scott {Trans., 1909, 95, 1200), C = 12-017
when Ag=-- 107-88. A single experiment with the corresponding
methyl compound gave C= 12-019. These values are too high to be
accepted until they have been coutirmed by other methods.

From the density of methane, Baume and Perrot {Compt. rend.,

1909, 148, 39) find C- 12-004. From the density of toluene, as
detei-mined by Ramsay and Steele, Leduc (Co»i/»<. rend., 19U9, 148,
832) computes C = 12-003.

Iodine and Silver. — Baxter and Tilley {J. Amer. Chem. Soc, 1909,
31, 201) have determined the ratio between iodine pentoxide and
silver. The pentoxide was reduced by means of hydrazine, and the
hydriodic acid so produced was balanced in the usual way against
silver. From the ratio thus found, IgOj : : 2Ag : : 100 : 64-6225 and
64-6230 (two series), combined with the ratio 1 : Ag : : 100 : 84-8843,
the authors find that the atomic weight of Ag lies between 107-847
and 107-850. The corresponding value for iodine is 1 = 126-891.

Phosphorus. — From the density of phosphine, PH^, Ter Gazarian
{Compt. rend., VdO'd, 148, 1397) finds P = 30-906.

Arsenic. — Atomic weight redetermined by Baxter and Coflin
{J. Amer. Chem. Soc, 1909, 31, 297). The ratios Ag.^AsO^ : 3AgCl
and AggAsO^ : 3AgBr were determined by two methods, one by solu-
tion and precipitation in the usual way, the other by heating the
arsenate in a stream of hydrochloric or hydrobromic acid. The
final mean result is As = 74-957 when Ag= 107*880.

Chromium. — From analyses of silver chromate by two methods,
Baxter, Mueller, and Hines {J. Amer. Chem. Soc, 1909, 31, 529) find
Cr = 52-008 when Ag=- 107-88, With similar analyses of silver

2218 REPORT OF THE INTERNATIONAL

dichiomate, Baxter and Jesse {J. Anier. Chem. Soc, 1909, 31, 541)
find Ci- = 52-013. The mean value is 52-01.

2'ellurium. — Lenher {J. Ainer. Chem. Soc, 1909, 31, 20) converted
the double bromide KjTeBr,. into 2KC1 by heating, first in a stream of
chlorine, and afterwards in hydi'ochloric acid. Sixteen very concordant
experiments were made, giving the molecular ratio between the two
compounds. The final mean value is Te= 127'55.

Mercury. — Analyses of mercuric chloride have been made by
Easley,* who determined the proportion of mercury in the compound,
and also the ratio HgCl2 : 2AgCl. By the first method, Hg = 20048 ;
by the second method, Hg- 200-62. These values are surprisingly
bigh ; but as Easley is to continue his investigation, it would be unwise
to accept them until his work is all done. It is quite possible that the
increase m?y be ultimately verified.

Palladiu7n.— Atomic weight determined by Gutbier, Haas, and
Gebhardt t by autxlyses of palladosammine bromide. The final most
probable mean value when N2H^r2 = B193-908 is Pd = 106-689.

Knjpton and Xenon. — Moore {Trans., 1908, 93, 2181) isolated
krypton and xenon in considerable quantities from the residues from
120 tons of liquid air. Calculated from the densities of the two gases,
the atomic weights are Kr = 83-012 and Xe= 130-70.

It will be seen from the evidence given above that few changes are
needed in the table of atomic weights. Chromium, 52-01, may be
rounded off to 52, as compared with the 52-1 formerly accepted.
Arsenic becomes 74-96, in accordance with the work of Baxter and
Coflan. The new values for krypton and xenon should also be adopted.
As regards mercury, action may be deferred until more evidence is
received.

F. W. Clarke.

W. OSTWALD.

T, E. Thorpe.

G. Urbain.

* Private comviunication. Easloy's work is soon to be published.
+ J. pr. Chem., 1909, [ii], 79, 457. Tliis includes the work of Haas, cited iu the
Report for 1909.

COMMITTEE OF ATOMIC WEIGHTS, 1010.

2219

1910.
International Atomic Weights.

0 = 16.

0-16.

Aluminium

Al

27

1

Antimony

Sb

120

2

Argon

A

39

9

Arsenic

As

74

96

Barium

Ba

137

37

Bismuth

Bi

208

0

Boron

B

11

0

Bromine

Br

79

92

Cadmium

Cd

112

40

Caesium

Cs

132

81

Calcium

Ca

40

09

Carbon

C

12

00

Cerium

Ce

140

25

Chlorine

CI

35

46

Chromium

Cr

52

0

Cobalt

Co

58

97

Columbium

Cb

93

5

Copper

Cu

63

57

Dysprosium

Dy

162

5

Erbium

Er

167

4

Europium

Eu

152

0

Fluorine

F

19

0

Gadolinium

Gd

157
69

8

Gallium

Ga

9

Germanium

Ge

72

5

Glucinum .

Gl

9

1

Gold

Au

197

2

Helium

He

4

0

Hydrogen

H

1

008

Indium

In

114

8

Iodine

I

126

92

Iridium

Ir

193

1

I ron

Fe

55
83

85

Krypton

Kr

0

Lanthanum

La

139

0

Lead

Pb

207

10

Lithium

Li

7

00

Lutecium

Lu

174

0

Magnesium

Mg

24

32

Manganese

Mn

54

93

Mercury

Hg

200

0

Molybdenum Mo

Neodymium Nd

Neon Ne

Nickel Ni

Nitrogen N

Osmium Os

Oxygen 0

Palladium Pd

Phosphorus P

Platinum Pt

Potassium K

Praseodymium Pr

Radium Ka

Rhodium Kh

Rubidium Rb

Ruthenium Ru

Samarium Sa

Scandium Sc

Selenium Se

Silicon Si

Silver Ag

Sodium Na

Strontium Sr

Sulphur S

Tantalum Ta

Tellurium To

Terbium Tb

Thallium Tl

Thorium Th

Thulium Tm

Tin Sn

Titanium Ti

Tungsten \V

Uranium U

Vanadium V

Xenon Xe

Ytterbium (Neoytterbium) Yb

Yttrium Y

Zinc Zn

Zirconium Zr

96

144

20

58

14

190

16

106

31

195

39

140

226

102

85

101

150

44

79

28

107

23

87

32

181

127

159

204

232

168

119

48

184

238

51

130

172

89

65

90

INDEX OF AUTHORS' NAMES.

TRANSACTIONS AND PROCEEDINGS. 1909.
(Marked T. and P. respectively.)

Agnew, James IVatson. See George

Gerald Henderson.
Alcock, {Miss) Mary. See Gilbert

Thomas Morgan.
AUmand, Arthur John, the electiomotive
heliaviour of cuprous oxide aud cupiic
hydroxide iu alkaline electrolytes, T. ,
2151 ; P., 258.
Anderson, [Miss) Emma Aleoeander. See

Jolin Kerf cot Wood.
Auld, Samuel James Manson, the hydro-
lysis of ainygdaliu byemulsiii. Part
III. Synthesis of rf-beiizaldehyde-
cyanohydriii, T. , 927 ; P., 62.
an examination of irritant woods.
Part I. Chloroxylonine from East
Indian satin wood, T., 964 ; P.,
148.

B.

Bain, {Miss) Aliee Mary. See IVilliam

Hobsoii Mills.
Baker, {Miss) Sarah Martha, a theory
ref^anliiig the configuration of certain
unsaturated comjjounds ; and its ap-
plication to the metallic ammines and
the cinnamic acids. P., 223.
Ball, Walter Craven, slow decomposition
of ammonium chromate, dicliromate,
and trichromate by heat, T. , 87.
a new method for the detection of
sodium, ciesium, and rubidium,
T., 2126 ; P., 284 ; discussion P.,
284.
Baly, Edward Charles Cyril, {Miss)
Kafherine Aliee Burke, and {Miss)
Effic Gwendoline Marsden, the absorp-
tion spectra of tlie nitrates iu relation
to the ionic theory, T., 1096 ; P., 144 ;
discussion. P., 145.

xcv.

Baly, Edivard Charles Cyril, John Nor-
ma)i Collie, and Herbert Edmeston
Watson, relation between absorption
spectra and chemical constitution.
Part XIII. Some pyrones and allied
compounds, T. , 144.
Banerjee, -V. C. See George Clarke,

juii.
Barger, George, isolation and synthesis
of j>)-hydroxyphenylethylamine, an
active principle of ergot soluble in
water, T., 1123 ; P., 162.
synthesis of honlenine, the alkaloid
from barley, T., 2193 ; P., 289.
Barger, George, and Arthur . James 'Ewins,
the action of phosphorus pentachloride
on the methylene ethers of catechol
derivatives. Part IV. Derivatives of
dihydroxypJienyl-acetic, -glycollic, and
-glyoxylic acids, T., 552; P., 86.'
Barger, George, and George Stanley
Walpole, further syntheses of /(-hydr-
oxyphenylethylamine, T., 1720;" P.,
229.
Barnett, Edward de Barry, the action of
hydrogen dioxide on thiocarbamides,
P., 305.
Barnett, Edward de Barry, and Samuel
Smiles, (the intramolecular rearrange-
ment of diphenylamine ortho-
sulphoxides, T., 1253 ; P., 195.
intramolecular rearrangement of the
diphenylamine sulphoxides ; pre-
liminary note, P., 74.
Barrett, William Henry. See Harold

Hartley.
Barrow, 'Fred. See Perey Faraday

Frankland.
Barrowcliff, Mo.rmaduke, and Frank
Tutin, the configuration of tropins
and i|/-tropine and the resolution of
atropine, T., 1966; P., 256; discus-
sion, P., 257.

7 G

INDEX OF AUTHORS.

Baudisch, Oscar, Gilbert Stan/cyEibheTt,
ami JFil Ham Henri/ TerkiTX, jun., the
reduction of 4-hydroxy-t)-toluic acid,
T.. 1870; P., 249.
Baudisch, Oscar, and IVilliam Henry
Perkin. j^tn., the reduction of 6-hydr-
oxy-o-toluic acid, T., 1883 ; P., 249.
Best, Stanlcij Robert, and Jocelyn Field
Thorpe, tlie formation and reactions
of imino-compounds. Part VII.
The formation of l:3-naphthylene-
diaminc from ;3-inano-a-cyano-7-
plienylpropanc, T. , 8.
the formation and reactions of imino-
compounds. Part VIII. The form-
ation of methyl derivatives of
2-phenyl-l:3-naphthylenediamine
from the three tolylacetouitriles, T.,
261 ; P., 28.
the formation and reactions of imino-
compounds. Part IX. The form-
ation of derivatives of cyclopentaue
from aS-dicyano-derivatives of
butane, T., 685; P., 92.
the formation and reactions of imino-
compounds. Part X. The formation
of imino-derivatives of pyrrole and
of isopyrrole from amino-nitriles,
T., 1506 ; P., 216.
Bloxam, William Po2}pleiveU. See

Frederick Thomas.
Boyd, David Manciman, and Herbert
Stanley Knowlton, the action of am-
monia on the glycide aryl ethers.
Part I. o-Tolyloxypropanolamines, T.,
1802 ; P., 235.
Boyd, David Runcivian, and Ernest
Robert Marie, the action of potassium
hydroxide on epichlorohydrin in pre-
sence of nionohydric phenols, T. , 1807;
P., 235.
Boyle, {Miss) Mary, the iodobenzene-
monosulphonic acids. Part I., T.,
1688 ; P., 35.
Brough, Bennett Hooper, obituary notice

of, T., 2202.
Burke, {Miss) Kaiherine Alice. See

Edicard Charles Cyril Baly.
Burt, Frank Play/air. See Robert

JFhythiw Gray.
Buttle, Bertram Haivard, and John
Theodore Hewitt, the constitution of
polynitrophenols in alkaline solution,
T., 1755 ; P., 231.

Cahen, Edivard. See Harry Frank

Victor Little.
Cain, Joh?i Cannell, nitrosoacetylamino-
derivatives of tlie benzene and di-
phenyl series, T., 714 ; P., 123
3-nitrodurene, P., 260.

Caldwell, Kenneth Somcrvillc, and IVil-
liam Holdsworth Hurtley, the distil -
lation of butter fat, cocoauut oil, and
their fatty acids, T., 853 ; P., 73.
Cameron, JVilliam. See George Gerald

Henderson.
Caton, Frederic IVilliam. See Frank

Tutin.
Chapman, David Leonard, and Patrick
Sarsfield MacMahon, the interaction
of hydrogen and chlorine, T., 136;
P., 15.
the retarding effect of oxygen on the
rate of interaction of chlorine and
hydrogen, T., 959; P., 148.
the influence of gaseous oxides of
nitrogen on the rate of interaction
of chlorine and hydrogen, T., 1717 ;
P., 224.
Chapman, David Leonard, and Leonard
Vodden, nitrogen chloride, T., 138 ;
P., 15.
Chattaway, Frederick Daniel, synthesis
of para-urazine from carbamide, T.,
235 ; P., 10.
the preparation of dichlorocarbamide,

T., 464 ; P., 72.
the preparation and properties of the
^V-tribromo-substituted hydrazines
(the diazonium perbromides), T.,
862; P., 120.
the action of the halogens on aromatic

hydrazines, T., 1065 ; P., 147.
ammonium perhalides, P., 163.
Chattaway, Frederick Da)iiel,a,iid Donald
Frederick Sandys Wiinsch, chlorine
derivatives of substituted carbamides,
T., 129 ; P., 11.
Clarke, Frank JVigylesworth, Gibbs
memorial lecture, T., 1299 ; P.,
171.
Clarke, George, jim., and <S'. C. Banerjee,
a glucoside from Tephrosicc p^trpurea ;
preliminary note. P., 16.
Clarke, Hans Timelier, and Samuel
Smiles, diethoxythioxan ; a relation
between the refractive power and
chemical activity of some sulphur
compoimds, T., 992; P., 145; dis-
cussion, P., 146.
Clarke, Reginald William Lane, and
Arthur Lapworth, cyanocarone, P.,
307.
Clewer, Hahert William Bentley. Sec

Frank Tutin.
Clough, George William. Bee Alexander

IiIcKenzie.
Cobb, John JV., the formation of sili-
cates, glasses, and glazes. P., 165.
Collie, •/(jh7i Nnrman. See Ehcnrd

Charles Cyril Baly.
Compton, Arthur. See Alfred Senier.

INDEX OF AUTHvORR.

2223

Coward, Hubert Frank. See HaroUl

Bdi'ii Dixon.
Crossley, Arthur William, and Cliarles
Gilling, hydroaiomatic ketones.
Part I. Syutliesis of triinethylcyclo-
hexenone (isoplioroue) and some
homologucs, T., 19.
note on the preparation of trimethyl-
cyclohexenoiie (isophoroue) from
ethyl malonate and clilorodimethyl-
cycloliexeuone, P., 96.
Crossley, .Irlhur Williarn, and Charhs
Herhrrt Hampshire, nitrotetramethyl-
diphunyl ; preliminary note, P., 162.
Crossley, Arthur jyHliam, and {Miss)
Xora Renouf, uitro-derivatives of
ortho-xylene, T., 202 ; P., 26.
substituted dihydrobenzenes. Part
III. The so-called 1:1 -dime thyl-A-^-
cycloliexadiene of Harries and An-
toni, T., 930 ; P., 145.
Gumming, Alexaiukr Clmrles, a method
for the measurement of vapour pres-
sures, T., 1772; P., 237.
Cunningham, (Miss) Mary, and Frederick
MdUwo Perkin, studies on the cobalti-
nitrites, T. , 1562.

Dakin, Henry Drysdale, the oxidation of
liydroxy-derivatives of benzaldehyde
and acetophenone, P., 194.
Davis, Harold. See Frederic Stanlnj

Kipping.
Davis, Morton James Fryce, See John

Joseph Sudborough.
Davis, Oliver Charles Minty, the quanti-
tative decomposition of the anilides :
a study in steric influence, T., 1397 ;
P., 197.
Davis, Oliver Charles Minty. See also

Francis Francis.
Dawson, Harry Met/forth, the nature of
ammoniacal copper solutions. Part
II. The solubility of cupric hydr-
oxide in ammoniacal sulphate solu-
tions, T., 370 ; P., 33.
a method for investigatin.i,' dissociation
equilibria in solutions, and its appli-
cation to the stud}' of aqueous
potassium mercuri-iodide solutions,
T., 870 ; P., 129.
Dawson, Harry Medforth, and {Miss)
May Sybil Leslie, dynamics of the
reaction between iodine and acetone,
T., 1860; P., 246.
Denham, IVilliam Smith, the action of
sulphur monochloride on salts of
organic acids : a convenient metiiod
of preparing anhydrides, T., 1235 ;
P., 179.

Denham, IVilliam Smith, preparation of
anhydrides by the action of thiouyl
chloride on salts of organic acids;
preliminary note, P., 294.

Desch, Cecil Henry. See Tliomas Martin
Lowry.

Dixon, H'irohl Baily, and Hubert Frank
Coward, the ignition-temperatures of
gases, T., 514 ; P., 67.

Dobson, (Miss) Mary Eli:Mbelh, John
Ferns, and William Henry Perkin,
jun., synthesis of c3'clohe.\anone-3-
carboxylic acid, T., 2010 ; P., 263.

Donnan, Frederick Ucorgc^ and Wilhclm
Schneider, the colour of acjueous solu-
tions of violuric acid, T., 956 ; P.,
148.

Doree, Charles, contributions to the
chemistry of cholesterol and copro-
sterol, T., 638 ; P., 88.

Dunlop, John Gunning Moore, and
Humphrey Owen Jones, the action of
ethylene dibromide on monomethyl-
aniline, T., 416; P., 61.

Dunn, Frederick Percy. See Martin
Onslow Forster.

Dunstan, Albert Ernest, and Ferdinand,
Bernard, Thole, the relation lietweeu
viscosity and chemical constitution.
Part IV. Viscosity and hydration in
solution, T., 1556; P., 219.

Dutta, Jatindra M. See A. Chandra,
Sirkar and Edivin Rov Watson.

E.

Eastburn, Wilfred ■James Stevenson.
See George Gerald Henderson.

Edgerton, John Percy, a new method of
preparing camphoric anhydride, P.,
149.

Egerton, Alfred Charles Glyn, divergence
of the atomic weights of the lighter
elements from whole numbers, T.,
238 ; P., 26.

Ewins, Arthur James, the action of
phosphorus pentachloride on the
methylene ethers of catechol deriva-
tives. Part V. Derivatives of proto-
catechuyl alcohol and protocatechuo-
nitrile, T., 1482; P., 210.

Ewins, Arthur James. See also George
Barger.

F.

Fenton, Henr/i ,/ohn Horstman, and
Freit Robinson, homologues of furfur-
aldehyde, T., 1334 ; P., 193.

Fenton, Henry John Horstman, and
]yilliam Arthur Reginald. Wilks, iso-
iminazolone, T., 1329 ; P., 192.

2224

INDEX OF AUTHORS.

Ferns. J<->hn. See (Miss) lifai-y Elizabeth

Dobson.
Ferraboschi, Frol'^ric, the oxidation of
mucic acid in presence of iron, T.,
1248; P., 178.
the production of ozone in the inter-
action between hydrogen dioxide
and sulphur dioxide ; preliminary
note, P., 179.
Fielding, JVilliauu See John Noriiuia

Pring.
Findlay, Alrxaiufer, and {3fiss) Evelyn
Marion Hickmans, the inlluence of
liydroxy- and alkyloxy-groups on
the velocity of saponification.
Part II., T., 1004 ; P., 152.
the partial racemisation of menthyl
r-niandelate, T., 1386 ; P., 196.
Findlay, Ale.randcr, William Ernest
Stephen Turner, and {Miss) Gertrude
Einily Owen, affinity constants of
hydroxy- and alkyloxy-acids, T., 938 ;
P., 146.
Finnemore, Horace, the constituents nf
Canadian hemp. Part II. Cyno-
toxin ; preliminary note, P., 76.
Finnemore, Hwace. See also John

Wade.
Flaschner, Otto, the action of /3-rays on
photosensitive solutions, T. , 327 ;
P., 34.
the miscibility of the pyridine bases
with water and the influence of a
critical-solution point on the shape
of the melting-point curve, T., 668 ;
P.. 71.
Flurscheini, Bernard, the relation be-
tween the strength of acids and
bases and the quantitative distribu-
tion of affinity in the molecule, T.,
718 ; P., 22.
the mechanism of the reduction of
nitroanilines and nitrophenols, P.,
21.
the relation between the strengths of
acids and bases, and the (quantitative
distribution of affinity in the mole-
cule. Part II., P., 193.
chciaical affinity and electrons ; pre-
liminary note, P., 261.
Forster, Martin Onslov), the triazo-group.
Part VII. Interaction of benzhydr-
oximic chloride and sodium azide,
T., 184 ; P., 25.
tlie triazo-group. Part IX. Trans-
formation of cinnamoylazoimide into
cinnamenylcarbimide (cinnamenyl
isocyanate), T., 433 ; P., 69.
Forster, Mo/rtin Onslov;, and Frederick
Percy Dunn, an interpietation of the
Hantzsch- Werner hypothesis, T., 425 ;
P., 68.

Forster, Martin Onslow, and Charles
Saninel Garland, studies in the cam-
phane series. Part XXVII. Cani-
phorylphenyltriazcn (eampliordiazo-
aminobenzene) and its bearing on the
constitution of diazoamino-compounds,
T., 2051; P., 244; discussion, P.,
244.
Forster, Martin Onslow, and Robert
Miiller, the triazo-group. Part VIII.
Azoimides of the monobasic aliphatic
acids, T., 191 ; P., 26.
the triazo-group. Part X. Triazo-
anlipyrine, T., 2072 ; P., 291.
Forster, Martin Onslow, and Tom
Thornley, studies in the camphane
series. Part XXVI. Aryl derivatives
of iminocaniphor, T. , 942; P., 145;
discussion, P., 145.
Fox, Julin Jacob, solubility of lead
sulphate in concentrated solutions of
sodium and potassium acetates, T.,
878 ; P., 128.
Francis, Francis, and Oliver Charles
Minty Davis, preparation of the acyl
derivatives of the aldehyde-cyano-
hydrins. Part I., T., 1403 ; P., 210.
Frankland, Percy Faraday, and Fred
Barrow, the acyl-bornylamines.
TiUt I. Fatty bornvlamides. T.,
2017; P., 263.
the acyl - bornylamines. Part II.
Aromatic bornylamides, T., 2026;
P., 263.
Friend, John Albert Newton, estimation
of iron by permanganate in the
presence of hydrogen chloride, T.,
1228; P., 150.
the action of steam on iiou ; prelim-
inary note, P. , 90.
the constitution of sulphurous, sul-
phuric, carbonic, and formic acids,
P., 91.
estimation of small quantities of
ferrous iron by potassium per-
manganate in the presence of
hydrogen chloride. P., 224.
Friswell, lUcho/rd John, obituary notice
of, T., 2204.

G.

Gardner, Henry Dent,, jun., and Walter
Norman Haworth, the condensation
of ketones and aldehydes with the
sodium derivative of ethyl cyano-
acetate, T., 1955; P., 250.

Gardner, JValfer Myers, and Herbert
Henry Hodgson, the iodination of
phenols and the iodometric estimation
of, and action of reducing agents on,
tannic acid, T. , 1819.

INDEX OF AUTHORS.

2225

Garland, I'hudis Samuel. See Martin

Onslmc Forster.
Garner, Frn/crick Banil. Sec Jamis

Char/m Philip.

Gebhard, J\iorvian Leslie, and Herbert

Jiryan Thompson, liiazoliydroxj'l-

amino-comiiounds ami tliu influence

of substituting gi-oujis on tlio stability

of their molecules. Fart I., T. , 707 ;

P., 70. Part II., T., 1115; P., 119.

Gibbs, [Olirer] lyokott, memorial

lecture on (Ci..\iiKE), T., l-.i90 ; P., 171.

Gilling, diaries. See Arthur William

Crossley.
Gilmour, Hubert, the mutarotation of
i,Hucose and its nitrogen derivative,
P., 225.
Gilmour, lloberl. See also Jaiues

Culquhoun Irvine.
Gittins, James Mylam. See John Joseph

Sudborough.
Gortner, Ross Aiken, a contribution to

the study of the oxydases, P., 30(5.
Gray, Francis Williain, direct proofs
of the presence of the hydroxyl
group in derivatives of anhydro-
acetonebenzil, T., 2131 ; P., 218.
isoraerides of anhydroacetonebenzil
and its derivatives, T., 2138 ; P.,
218.
Gray, Robert JFhyfhnr, and Frank Play-
fair Burt, the atomic weight of
"chlorine, T., 1633 ; P., 216.
Gray, Robert IVhytlan-, and (Sir) JFilliam
Ramsay, some physical i)roperties
of radium emanation, T., 1073 ; P.,
161 ; discussion, P., 162.
liquid and solid radium emanation,
P., 82.
Gregory, Arnold Jf'illiam, a colori-
nietric method for the estimation of
small quantities of vanadium, P., 232.

H.

Haas, Pavl, the condensation ot di-
methyldihydroresorcin with ethyl-
amine, T., 421 ; P., 19.
Hampshire, Charles Herbert. See Arthur

JFi/liam Crossley.
Hann, Archie Cecil Osborn. See Frank

Tutin.
Hansen, Edicard Kenneth, pl.ycoerythrin,
the pigment of the red alg», P., 117 ;
discussion. P., 117.
Harrop, {Miss) iJorothy, Roland Victor
Norris, and Charles Weizmann,
derivatives of naplithacenequinone.
Part III., T., 279; P., .33.
some derivatives of anthraquinone,
T., 1312; P., 203.

Hartley, Harold, and IFilliam Henry

Barrett, sodium s\dpliite and its

(•i|nililirium with water, T., 1178;

P., 164.

Hartley, Walter Koel, the constitution

of pani-benzoquinonc, T., 52.
Hartley, Walter Nacl, and Alfred Cod-
fr>y Cordon Leonard, the absorption
spectra of para-bi-nzoquinone, (juinol,
and (luinhydrone in tlic state of vapour
and in solution, T. , 34.
Haworth, Waller Norman, the con-
ilcnsation of ketones and aldehydes
with the sodium derivative of ethyl
cyanoacetate, T., 480 ; P., 76.
Haworth, Waller Norman. See also

Hcnnj Jknt Gardner, ./it/*.
Hay, dani>s Cordon. See RapJiael

Meldola.
Henderson, C'-orge Gerald, and James
If'alson Agnew, contributions to tlie
chemistry of the terpenes. Part IV.
The oxidation of pinene with mercuric
acetate, T., 289; P., 35.
Henderson, George Gerald, and William
Cameron, contributionstotliechennstry
of the terpenes. Part V. The action
of clironivl chloride on terpinene and
on linionene, T., 969 ; P., 151.
Henderson, George Gerald , and Wilfred
James Stevenson Eastburn, the con-
version of pinene into solirerol, T.,
1465 ; P., 211.
Hewitt, John Theodore, Sidney Herbert
Newman, and Thomas Field Winmill,
studies in the azine series. Part I.
The constitution of safranine, T. , 577 ;
P., 86.
Hewitt, Jcjhn Theodore, and Fcrdiiumd
Jiernard Thole, the colour and con-
stitution of azo-compounds. I'art l\.,
T., 1393 ; P., 208.
Hewitt, John Thealore, and William
Thomas, the colour and constitution
of azo-compounds. Part III., T.,
1292; P., 190.
Hewitt, John Theodore. See also Bertram

Hairard Buttle.
Hibbert, (Miss) Eva. See Edmund

Knecht.
Hibbert, Gilbert Stanley. See Oscar

Baudisch.
Hibbert, Harold, the estimation of
hydroxyl derivatives in mixtures of
organic compounds. P., 57.
a simple method for determining the
chemical affinity of organic sub-
stances, P., 57 ; discussion, P.,
58.
the sta'oility of compounds derived
from tertiary amines and magnesium
alkyl halides, P., 118.

2226

INDEX OF AUTHORS.

Hibbert. ITarold, and Archilahl Wise,

a now method for (ho soi>aiatioii of

toitiarv from secondary and primary

aminos. P., 119.

Hibbert, llarohl. See also John Joseph

Sudborough.
Hickmans. {MisA) Evelyn Manon. See

Alcramlir Findlay.
Hicks, Williaiit Longton. See Arthitr

1 1 'a hi, Titherley.
Hilditch, Thonuts Fn-cy, the effect of
coiiti_i,'uons unsaturated groups on
optical activity. Part I., T., :331 ;
P., 29.
the effect of contiguous unsaturated
groups on optical activity. Part II.
Acids containing two adjacent
ethenoid groups, T., 1570; P.,
214.
the effect of contiguous unsaturated
groups on optical activity. Part III.
The normal series of fatty dibasic
acids, T., lf.78 ; P., 214.
Hodgson, Herbert, Henry. See Walter

Jlycrs Gardner.
Holmes, John, and Philip John Sageman,
contributions to the theory of solutions,
T., 1919; P., 231.
Holt, Alfred, jun., the decomposition of
carbon dioxide by tlie silent electric
discharge, T., 30.
Hope, Eihcard, and IViJliam Henry
Parkin, jun., the action of bromo-
cyclohexane and of 4-bromo-l-
methylcyclohexane on the sodium
derivative of ethyl malouate, T. ,
1360 ; P., 207.
ethyl benzoylacetate, T. , 2042 ; P. ,
296.
Howard, Hiihert. See Frank Georyc

Pope.
Humphries, Herbert Brooke Perren. See

Alexander McEenzie.
Hurtley, William Holdsicorth. See

Kenneth Soinerville Caldwell.
Hynd, Alexander. See James C'olquhoun
Irvine.

Inglis, John Kenneth Harold, and Alfred
S'idell Mason, action of Grignard's
reagent on ethyl oxalate, P., 195.

Irvine, James Coleiuhmm, a polarimetric
method of identifying chitin, T., 564 ;
P., 89.

Irvine, Ja/mes C'olquhoun, and Hobert
Gilmour, tlie constitution of glucose
derivatives. Part II. Condensation
derivativea of glucose with aromatic
amino-compounds, T., 1545; P.,
218.

Irvine, James Colqulioun, and Ale.rander
Hynd, monomethyl hovulose and its
derivatives : constitution of hevulose-
diiicetone. T,, 1220; P., 176.

Isherwood, Percy Claude Cameron, the
coloured salts and derivatives of the
thiovioluric acid group ; preliminary
note. P., 120,

Jackson, (Miss) Kate Maud, and Henry
Allen DiKjdalc Neville, substituted
amides of tartaric acid. P., 226.

James, Thomas Campbell, and John
Joseph Sudborough, halogen deriva-
tives of cinnainic acid, T. , 1538 ;
P., 211.

Jerusalem, George, the morphotropic
relationships between the derivatives
of picric acid, T., 1275 ; P., 201.

Jones, Bernard Mouat, the spontaneou,'?
crystallisation of solutions of sodium
carbonate and sodium thiosulpliate,
T., 1672 ; P., 213.

Jones, Hicmphrey Given, and Hubert
Sanderson Tasker, the action of
mercaptans on acid chlorides. Part I.
Oxalyl chloride : the mono- and di-
thio-oxalates, T., 1904 ; P., 247.
thio-oxalates ; preliminary note, P.,
159.

Jones, Humphrey Owen. See also John
Grinning Moore Dunlop, and Hubert
Sanderson Tasker.

Jones, Lionel Manfred. See Thomas
Slater Price.

Jones, William Jacob, and Kennedy
Joseph Premti Orton, the chlorination
of acetanilide, T., 1056; P., 146.

Jones, William Jacob. See also Kennedy
Joseph Previt6 Orton.

Jowett, Hooper Albert Dickinson, and
Frank Lee Pyman, relation between
chemical constitution and physi-
ological action in the tropeines.
Part II., T., 1020; P., 165.

Kametaka, T. , and Arthur George Perkin,

carthamine ; ju'eliminary note, P.,

223.
Kay, Fraiwis William, the conversion

of r?-a-methylisoserine into d-a-

methylglyceric acid, T., 560 ; P., 90.
Kenyon, Joseph. See llobrrt Hmrson

Pickard.
Kipping, Frederic Stanley, a study of

some asymmetric compounds, T. , 408;

P., 55,

INDEX OF AUTHORS.

2227

Kipping, Frederic Stanley, niul Harold
Davis, organic derivatives of silicon.
Part IX. Experiments on the reso-
lution of (W-bcnzyletliyljiropyliso-
butvlsilicancsuliilionic acid, T. , 69;
P., "9.
Kipping, Frederic Stanley, and Bernard
Dunstan Wilkinson Luff, isomeric
derivatives of ]>liosplioric acid, P., 203.
Kipping, Frrdcric Stanley, and Ueoji'rnj
Martin, the action of fuming sulphuric
ueid no triphenylsilicol, T.,489 ; l'.,66.
Kipping, Frcdcrir Stanley, and Williaui
Jack!<on Pope, crystallisation of ex-
teriiall}- compensated mixtures, T..
103; P., 9.
Kipping, Frederic Stanley. See also
Bernard I)uniif((n Wilkinson Lxxff,
Geoffrey Martin, and Arthur Henry
Salway.
Knecht, Edmund, the reduction of
perchlorates \>\ titauous salts, P., 229.
Knecht, Edniund,&nA. {Miss) Eva Hibbert,
a volumetric process for the estima-
tion of tungsten, P., 227.
Knowlton, Herbert Stanley. See David

Jlnncimitn Boyd.
Knox, .Joseph, the solubility of bismuth
trisulphide in alkali sulphides and
of bismuth trioxide in alkali liydr-
oxides, T., 1760 ; P., 226.
the volumetric estimation of mercury
and the estimation of silver in
presence of niereurj', T., 1768 ; P.,
227.
Krieble, Vernon K. See James IVallacc
Walker.

L.

Lamplough, Francis Edward Everard,
note on the determination of the
rate of chemical change by measure-
ment of the gases evolved. P., 23 ;
discussion, P., 24.
the determination of the rate of de-
composition of benzenediazonium
chloride, P., 166.
Lang, JVilliam Robert, and John Obins
Woodliouse, some esters of arsenious
acid. Part II. Resorcinyl arsenite,
P., 199.
Lapworth, Arthur, note on the variation
in the catalytic activity of mineral
acids with changes in their concentra-
tion, P., 19.
Lapworth, Arthur, aud James Biddick
Partington, the influence of water on
the availability of hydrogen chloride
in alcoholic solution. P., 'i07.
Lapworth, Arthur, and £//.•«« "Wechsler,
experiments on sulistituted alleuecarb-
oxylic acids. Part I., P., 307.

Lapworth, .Irtliur. See also Bcfjinald

IVilliani Lane Clarke.
Leonard, Alfred Godfrey Oordon. See

Waller Noel Hartley.
Leslie, (.1/i.s.s) May Sybil. See Harry

Mrd/iirth Dawson.
Le Sueur, Henry llondel, formation of
heterocyclic comiiounds. Pait I.
1 -Phenyl iiyrrolidine-2 : 5-dicarboxylic
acid from adipic acid, T., 273; P., 36.
Lewis, Samuel Judd. See Edgar

"Wedekind.
Lewis, in/liam Cudmore McCullaejh,
adsorption in relation to Gibbs's theor\':
the mercury adsorbing surface, P.,
2r)8 ; discussion, P., 258.
Little, Harry Frank Victor, Edward
Cahen, and Gilbert Thomas Morgan,
the estimation of arsenic in organic
componnd.s, T., 1477; P., 212.
Lloyd, /'rrri/ Vivian. See Clarence,

.Irthur Seyler.
Lowry, Thmnas Martin, and Cecil Henry
Desch, studies of dynamic isomerism.
Part VIII. The relationshiji be-
tween absorption spectra and iso-
meric change. Absorption spectra
of halogen, nitro-, and methyl
derivatives of camphor, T. , 807 ; P. ,1 3.
studies of dynamic isomerism. Part
IX. Tlie relationshij) between ab-
sorption spectra and isomeric change.
Absorption spectra of sulphonic
derivatives of camphor, T., 1840 ;
P., 192.
Luff, Bernard Thiufitan Wilkinson, and
Frederic Stanley Kipping, the resolu-
tion of asymmetiical derivatives of
phosphoiic acid, T., 1993 ; P., 256.
Luff, Bernard Dunstan Wilkinson. See
also Frederic Stanley Kipping.

M.

McCombie, HamiHon, aud {Miss) Ethel
Parry, condensations of cyanohydrins.
Part I. C(nidensation products from
anisaldehydecyanohydrin and cin-
namaldehydecyanohydrin, T., 584 ;
P., 95.

McDonald, David Paterson. See Thomas
Stcv:art Patterson.

McKenzie, Ahxancler, and George
jniliam Clough, experiments on the
AValden invension. Part II. The
interconversion of the optically active
mandelic acids, T., 777 ; P., 70.

McKenzie, Alceaiuler, and Herbert
Brooke Perren Humphries, studies in
asymmetric synthesis. Part VIII.
The asymmetric .synthesis of /-mandelic
acid, T., 1105; P., 164.

2228

INDEX OF AUTHORS.

McKenzie, Alexander, and nermann

AuQust Miiller, studies in asymmetric

svii'tLesis. Part VII. The influence

of the (7-aniyl group, T., 544 ; P., 88.

MacKey, John Francis, some esters of

antiii ony trioxide, T., 604 ; P., 98.
MacMahon, Patrick Sarsjicld. See David

Leonard Chapman.
Marie, Eriust Robert, the estimation of
carbonates in presence of nitrites,
sulphides, or sulphites by means
of potassium dichromate, T., 1491 ;
P., 154.
the action of carbon dioxide on nitrites,
P., 74.
Marie, Emcd Boherl. See also David

Runcima.n Boyd.
Marsden, [Miss) EJjie Gwendoline. See

Edward Charles Cyril Baly.
Marsh, James Ernest, and Robert de
Jersey Fleming Struthers, some
mercury derivatives of camphor, T.,
1777 ; P., 228.
Martin, Geoffrey, and Frederic Stanley
Kipping, benzyl and ethvl derivatives
of silicon tetrachloride, T., 302 ; P.,
27.
Martin, Geoffrey. See also Frederic

S'anley Kipping.
Mason, Alfred Sidell. See John Kenneth

Harold Inglis.
Meldola, Raphael, and James Gordon
Hay, syntheses with phenol deriva-
tives containing a mobile nitro-
group. Part II. The interaction of
2:3 : 5-trinitro-4-acetylamiuophenol
and amines (continued), T., 1033 ;
P., 167.
2:3:5-tiinitro-4-aminophenol and de-
rivatives, T., 1378 ; P., 207.
Meldrum, Andreiv Norman, ami William
Henry Perkin, ywH., the reduction of
5-hydroxy-?/i-toluic acid, T., 1889 ;
P., 249.
Mendeleeff, Dmitri Ivanovitsch, memorial

lecture on (Tilden), T., 2077.
Merriman, Richard William. See John

Wade.
Micklethwait, (Miss) Frances Afary Gore.

See Gilbert Thomas Morgan.
Mills, William Hobson, and [Miss) Alice
Mary Bain, optically active 4-oximino-
cyc'lohexanecarboxylic acid and the
coDfi.guration of the oxiraino-group ;
preliminary note, P., 177.
Mitchell, Alec Duncan, and Clarence
Smith, constitution of hydroxyazo-
compound.s. Part II. Action of
niercuiic acetate on benzeneazo-
naphthols, T., 1430; P., 209.
volumetric estimation of sulphates,
T., 2198 ; P., 291.

Moir, James, a method of harmonising
the atomic weights, T., 1752 ; P., 213.

Montgomerie, Harvey Hugh, See
Thomas Steicart Patterson.

Moody, Gerald Tattersall, the nrstiug of
iron. P., 34.

Moore, Charles Watson, the constituents
of tlie rhizome of Apocynum androsse-
mifolium, T., 734 ; P., 85.

Moore, Charles Jf'atson. See also
Frederick Belding Power.

Moore, Tom Sidney. See Ncvil Vincent
Sidgwick.

Moore, Williatn Roman. See Gilbert
Thomas Morgan.

Morgan, Gilbert Thomas, and (Miss)
Mary Aleock, the colour and constitu-
tion of diaznnium salts. Part I., T.,
1319; P., 202.

Morgan, Gilbert Thomas, and (Miss)
Frances Mary Gore Micklethwait,
organic derivatives of arsenic. Part
II. Triaminotriphenylarsine oxide
and tricamphorylarsinic acid, T., 1473 ;
P., 212.

Morgan, Gilbert Thomas, (Miss) Frances
Mary Gore Micklethwait, and George
Stafford Whitby, organic derivatives
of antimony. Part I. Tricamphoryl-
stibine chloride and triphenylstibine
hydroxynitrate and hydroxysulphate,
P., 302.

Morgan, Gilbert Thomas, and WiUiam
Roman Moore, dicamphorylphosphinic
acid, P., 310.

Morgan, Gilbert Thomas, and Joseph
Allen Pickard, the production of para-
diazoiniides from alkyl- and aryl-
sulphonyl-para-diamines. A general
reaction, P., 300 ; discussion. P., 301.

Morgan, Gilbert Thomas. See also

Harry Frank Victor Little.
Mouilpied, Alfred Theophihis dc, and
Alexander Rule, tetraketopiperazine.
Part II., T., 549; P., 71.
Mountain, Harold. See (Miss) Martha

Annie Whiteley.
Mtiller, Hermann August. See Alex-
ander McKenzie.
Miiller, Robert. See Martin Onslow

Forster.
Muir, Mattheic MoncHeff Pattison, iodine
dioxide, T., 656 ; P., 88.

N.

See

Neville, Henry Allen Dugdale.

(Miss) Kate Maud Jackson.
Newman, Sidney Herbert. See John

Theodore Hewitt.
Norris, Roland Victor. See (Miss)

Iiorothy Harrop.

INDEX OF AUTHORS.

2229

0.

Orton, Kennedy Joseph Previti, and
IVilUam Jacob Jones, a crystalline
bleaching powder, T., 751 ; P., 74.
primary interaction of chlorine and

acetunilides, T., 1456 ; P., 196.
cliloriuation and broniination of acyl-
aniliJes. A direct }irocess ; pre-
liminary note. P., 233.
chlorination and broniination of acyl-
anilides. Part II. The action of
the halogen acids on chloro- and
bromo-acylaminobenzenes ; prelim-
inary note, P., SOii.
Orton, Kennedy Joseph Previtd. See
also JVillia)n Jacob Jones, and (Miss)
Alice Emily Smith.
Owen, (Miss) Gertrude Emily. See
A lexander Findlay.

Parry, (Miss) Ethel. See Hamilton

McCombie.
Parry, IVilliam, ethyl a-hydroxyiso-

butyrate, P., 305.
Partington, James Riddick. See Arthur

Lapworth.
Patterson, Thomas Stewart, and David

Paterson McDonald, the influence of

solvents on the rotation of ojitically

active compounds. Part XIV. Ethyl

tartrate in benzaldehyde and in c^uin-

oline, T., 321 ; P., 36.
Patterson, Thomas Stewart, and Harvey

Hugh Montgomerie, the influence of

solvents on the rotation of optically

active compounds. Part XV. ilixtd

solvents, T., 1128 ; P., 151.
Peachey, Stanley John. See William

Jackson Pope.
Perkin, Arthur George, indoxylic acid,
T., 847; P., 126.

the coloirring matters of the flowers of
Hibiscus sabdariffa and Thespasia
lampas, T., 1855; P., 248.

the coWring matter of cotton flowers,
Gossypium herbaceum. Part II.,
T., 2181 ; P., 291.

the reduction of indirubin, P., 127.
Perkin, Arthur George, and Frederick

Thomas, indican. Part II., T., 793;

P., 125.
Perkin, Arthur George. See also T.

Kametaka, and Frederick Thomas.
Perkin, Frederick Molliro, and Lionel

Pratt, action of alcohols on metallic

calcium, T., 159; P., 18.
Perkin, Frederick MoJhvo. See also

(Miss) Mary Cunningham.

Perkin, J Til Ham Henry, jun., JVilliajn
JncksoH. Pope, and Otto Wallach,
optically atttive substances containing
no asymmetric atom, 1-methylcyclo-
hexylidcne-4-acetic acid, T., 1789 ;
P.. 83, 230; discussion. P., 84.

Perkin, U'illiam Henry, jioi., and Robert
Kobinson, braziliu, haematoxyliu and
their derivatives. Part X. The con-
stitution of trimethyllnazilone, of a-
and 3-anhydrotrimethylbrazilone, and
of the correspoudint; luematoxylin de-
rivatives, T., 381 ; P., 31.

Perkin, JFilliam Henry, jun., Robert
Robinson, and Frederick Thomas, syn-
thesis of cotarnic acid, T., 1977 ; P.,
262.

Perkin, IVilliayn Henry, jun., and
Jolin Lionel Simonsen, cyclobut-
an('-l:3-dicarboxylic acid and some
of its derivatives, T., 116G ; P.,
178.
note on the condensation of acetone
and hipjiuric acid. P., 104.

Perkin, IV illiam Henry, jun. See also
Oscar Baudisch, (Miss) Mary Eli~.u-
6£<// Dobson, Edward ILo'pe, and A^idrew
Norman Meldrum.

Philip, James Charles, and Frederick
Basil Garner, iniiiience of various
sodium salts on the solubility of spar-
ingly soluble acids. Part II., T.,
1466 ; P., 212.

Phillips, Harry Edward William, the
electrical conductivity of phosphoric
acid, T., 59.

Pickard, Josepli Allen. See Gilbert
Thomas Morgan.

Pickard, Robert Huivson, and Joseph
Kenyon, resolution of racemic alcohols ;
preliminary note. P., 167.

Pickard, Robert Howson, and Joseph
Yates, optically active reduced naph-
thoic acids. Part IV. Comparison of
the rotatory powers of the di- and
tetra-hydronaphthoic acids with those
of phenylallylacetic, a-phenylvalerie,
/3-phenyl-o-ethyl-, and ;8-plienyl-a-
methyl-propionic acids, T. , 1011 ; P.,
152.

Pickering, Spencer Pereival Umfreville,
hydration of precipitates, T., 123 ;
P., 12.
the carbonates of copper and the cupri-
carbonates, T., 1409 ; P., 188 ; dis-
cussion, P., 188.

Pope, Frank George, and Hubert Howard,
the condensation of benzaldehyde with
resorcinol. P., 304.

Pope, William Jackson, and Stanley John
Peachey, the allcyl compounds of
platinum, T., 571 ; P., 96.

2230

INDEX OF AUTHORS.

Pope, William Jackson, and John Read,
condensation of oxynicthj'lenecamphor
with primary and secondary aniino-
compoiinds, T., 171 ; P., 18.
Pope, IVilliam Jackson. See also
Fi-idcric ,Sta)th')jKi]^]^ing and iniliain
Henry Perkin, y«?(.
Power, Frederick Belding, and Charles
IVatson Moore, the constituents of
the bark oi Pninus serotina. Isola-
tion of Z-mandelonitrile glucoside,
T., 243 ; P., 27.
the constituents of the fruit of Echal-
Uum Elaterium, T., 1985 ; P., 260.
Pratt, IJo7iel. See Frederick Mollwo

Perkin.
Price, Thomas Slater, and Lionel Man-
fred Jones, the benzyl and nitrobenzjd
selenosulphates and the benzyl and
nitrobenzyl diselenides, T., 1729; P.,
234.
Price, Thomas Slater, ^nd Boitglas Frank
Twiss, the preparation of disulpli-
ides. Part V. Diethyl esters of
o-dithiodibutyric, a-ditliiodiisobu-
tyric, and a-dithiodiisovaleric acids,
T.,1050; P., 165.
the preparation of disulphides. Part

VI. Note on a new method of pre-
paring disulphides, T., 1489 ; P.,
211.

the preparation of disulphides. Part

VII. The nitrobenzyl mercaptans
and disulphides, T., 1725 ; P., 232.

the preparation of disulphides. Part

III. The nitrobenzyl disulphides : a

correction. P., 32.

Prideaux, Edmund Brydges Rudhall, the

atomic volumes of phosphorus. Part

II. Phosphorus and bromine, T., 445.

Priestley, John Gillies. See Siegfried

Ruhemann.
Pring, John- Norman, and William
Fielding, the preparation at high tem-
peratures of some refractory metals
from their chlorides, T., 1497 ; P.,
215.
Purvis, Jdlin Edward, the relationship
between tlie constitution and absorp-
tion spectra of pyridine and various
derivatives, T., 294 ; P., 14.
Pyman, Frank Lee, isoquinoline deriva-
tives. Part I. Oxidation of laud-
anosine, T., 1266; P., 190.
isoquinoline derivatives. Part II.
The constitution of the reduction
products of j)apaverine, T., 1610 ;
P., 217.
isoquinoline derivatives. Part III.
The oxidation of substituted 1-
beuzvltetrahydroisoquinolines, T.,
1738"; P., 230.

Pyman, Frank Lee. See also Hooper
Albert Dickinson Jowett.

R.

Ramsay, [Sir) William, presidential

address, T., 624.
Ramsay, {Sir) William. See also Eobert

Whytlan- Gray.

Ray, Prafulla CJiandra, molecular

volumes of the nitrites of barium,

strontium, and calcium, T. , 66.

the decomposition and sublimation of

ammonium nitrite, T., 345 ; P., 56.

Read, John. See William Jackson Pope.

Renouf, (Miss) Nora. See Arthur

William Crossley.
Reynolds, James Emersan, silicon re-
searches. Part XI. Silicotetra-
pyrrole, T., 505.
silicon researches. Part XII. The
action of silicochloroform on potass-
ium pyrrole, T., 508.
silicon researches. Part XIII. Silicon
halides and pyridiue, acetouitrile,
etc., T., 512.
Rivett, Albert Gherhury David. See

Nevil Vincent Sidgwick.
Robertson, Fobcrt, tlie velocity of de-
composition of nitro£(lycerin by heat.
Parti., T., 1241; P.", 179.
Robinson, Fred. See Henry John Hoi'st-

man Fenton.
Robinson, Frederic William, double and
triple ferroeyanides of magnesium, alu-
minium, and cerium with potassiimi
and ammonium, T., 1353 ; P., 195.
Robinson, llohert, a new synthesis of
oxazole derivatives, T., 2167 ; P., 295.
Robinson, Robert, and John Lionel Simon-
sen, experiments on the constitution
of the aloins. Part I., T., 1085;
P., 153.
experiments on the constitution of the
aloins; preliminary note. P., 76.
Robinson, llohert. See also William

Henry Perkin, jun.
Ruhemann, Siegfried, formation of cyclo-
hexanone derivatives from olefinic
compounds, T., 109 ; P., 10.
action of mustard oils on the ethyl
esters of malonic and cyanoacetic
acid.s. Part II., T., 117; P., 14.
the condensation of amides with esters
of acetylenic acid.s, T., 984 ; P., 87 ;
discussion. P., 87.
diketodiphenylpyrroline and its ana-
logues, T., 1603; P., 220.
Ruhemann, Siegfried, and John Gillies
Priestley, the action of ethyl carbamate
on esters of organic acids and nmstard
oils, T., 449 ; P., 62.

INDEX OF AUTHORS.

2231

Tivile, Alexander. See Alfred Theophilus
de llouilpied.

S.

Sageman, Ph Hip John. See Juhn Holmes.
Salway, Arthur Henri/, the action of
nitric acid on the ethers of aromatic
hydroxj-aldeliydes, T., 1155; P.,
160; discussion, P., 161.
the synthesis of substances allied to
cotarnine, T., 1204 ; P., 175.
Salway, Arthur Henry, and Frederic
Stanley Kipping, atinospheric oxida-
tion of /3-niethylhydrindone, T., 166 ;
P., 16.
Sand, Henry Julius Salomon, the rapid
electro-analytical deposition and separ-
ation of metals. Part III. Preliminary
note, P., 228.
Schneider, Jf'i/hel/n. See Frederick

George Donnan.
Scott, Alexander, tlie molecular weight
of tetraethylammonium bromide and
the atomic weight of carbon, T.,
1200; P., 173; discussion, P., 174.
the correction of weights of substances
weighed in air to weights in a
vacuvim. P., 286.
tlie combustion of naphthalene and
other organic substances and the
atomic weight of carbon, P., ;j10.
Senier, Alfred, and Arthur Compton, the
synthesis of acrid ines : tetramethyl-
acridines, dimethyluaphthacridines,
naplithaquinacridines, diquinacridines,
T., 1623; P., 220.
Senier, Alfred, and Frederick George
Shepheard, salicylidene-7/< -toluidine,
a new phototropic compound ; sali-
cylideueamines : salicylamides, T. ,
441 ; P., 61.
thiotetrahydroquinazolines,methylene-
carbamides, dicarbanilinomethjdene-
diamines and their homologues, T.,
494: P., 72.
studies in phototropy and thermo-
tropy. Part I. Avylidene- and
naphthylidene-amines, T., 1943 ; P.,
246.
Senter, George, reactivity of the halogens
in organic compounds. Part III.
Interaction of bromoacetic, o-bromo-
propionic, and a-bromobutyric acids
and their sodium salts with water
and with alkali, T., 1827 ; P., 236.
viscosity and association in binary
mixtures of liquids, P., 292.
Seyler, Clarence Arthur, and Percy Vivian
Lloyd, studies of the carbonates. Part
I. The equilibrium between calcium
carbonate and carbonic acid, T., 1347 ;
P., 199.

Shenstone, William Ashwell, obituary
notice of, T., 2206.

Shepheard, Frederick George. Sec Alfred
Senier.

Sheppard, Samuel Edward, the optical
and sensitising properties of the iso-
cyanine dyes, T., 15.

Shibata, Vi'tji, tlie a-^tion of tlie Orignard
reagent on phthalic esters, T. , 1449;
P., 209.

Sidgwick, yevil Vincent, and Tom Sidney
Moore, the rate of reaction of the tri-
])benyhiiet]iane dyes with acid and
alkali. Part II. Brilliant-green and
malachite-green, T., 889; P., 123.

Sidgwick, A'evil Vincent, and Albert
Cherbury Darid Rivett, the rate of
reaction of the tri[ilienvhnetluine dyes
with acid and alkali." Part III. Di-
aminotriphenylcarbinol, T., 899; P.,
124.

Simonsen, John Lionel, ■ci.w'X Jlobert Storey,
syntheses with the aid of monochloro-
methyl ether. Part II. The action of
monochloromethyl ether on the sodium
derivative of eth3'l acetoacetate, T.,
2106; P., 290.

Simonsen, John Lionel. See also JVil-
liain IL nry Perkin, jua., and Robert
Robinson.

Sii'kar, A. Chandra, and ,/atindra M.
Dutta, the reaction between potassium
permanganate and manganese sulphate
in acid solution, P., 249.

Sirkar, .1. Chandra. Sec also Edwin
Ji'oy Watson.

Slator, Arthur, and Douglaji FranklvrisB,
chemical dynamics of the reactions
between sodium thiosnlphate and
organic halogen compounds. Part III.,
T., 93.

Smedley, (Miss) Ida, the relation between

the chemical constitution and optical

properties of the aromatic a- and y-

diketones, T., 218 ; P., 17.

note on the coTistitution of the carb-

o.xyl group, T., 231 ; P., 16.
the stereiisomeric modifications of a0-
dibromobenzylacetophenone.P. ,259.

Smiles, Samuel. See Edward de Parry
Barnett and Hans Thaeher Clarke.

Smith, (Miss) Alice Emily, and Kennedy
Joseph I'revite Orton, acids as accelera-
tors in acetylation. Part II., T.,
1060; P., 166.

Smith, Clarence. See Alec Duncan
Mitchell.

Smythe, John Armstrong, benzyl sulph-
oxide : a possible example of dynamic
isomerism, T., 349.

Sonstadt, Edward, obituary notice of,
T., 2209.

OiO«:jO

INDEX OF AUTHORS.

Stevenson. (Sir) Thoma.'i, obituary notice
of, T.. 2213.

Storey, Jiobcrt. See Jolni Lionel
Simonsen.

Struthers, liohcrt dc Jersey Fleming.
See James Ernest Marsh.

Sudborough, Jolm Joseph, and Morion
JiDnest J'njee Davis, e.stciification con-
stants of substituted acrylic acids.
Part IV , T., 975; P., 147.

Sudborough, John Joseph, and James
Mylam Gittins, esteritication constants
of substituted acrylic acids. Part III.,
T., 315; P.. 31. "

Sudborough, John Joseph, and Harold
Hibbert, estimation of primary,
secondary, and tertiary amines. Part
I., T., 477 ; P.. 75.

Sudborough, John Joseph. See also
Tlioiiias Campbell James.

Tasker, Hubert. Sanderson, and Humphrey
Owen Jones, the action of mercaptans
on acid chlorides. Part II. The acid
chlorides of phosphorus, sulphur, and
nitrogen, T., 1910; P., 247.
Tasker, Hubert Sanderson. See also

Humphrey Owen Jones.
Thole, Ferdinand Bernard, note on the
anomalous viscosity of nitrobenzene,
P., 198.
Thole, Fenlinetnd Bernard. See also
Albert Ernest Dunstan and John
Theodore Hewitt.
Thomas, Frederiel; JVilliam Popplewell
Bloxam, and Arthur George Parkin,
indican. Part III., T., 824 ; P., 126.
Thomas, Frederick, See also Arthur
George Perkin and William Henry
Parkin, jiin.
Thomas, John, the isolation of the arom-
atic sulphinic acids, T., 342 ; P., 60.
Thomas, William. See John 2'heodfire

Hewitt.
Thompson, Herbert Bryan. See Norman

Leslie Gabhard.
Thornley, Tom. See Martin Onslow

Forster.
Thorpe, Jo'elyn Field, the formation and
reactions of imino-corapounds. Part
XI. The formation of l-iraino-2-
cyanocyclopropane from adiponi-
trile, T., 1901 ; P., 243 ; discussion,
P., 243.
the transformation of aliphatic nitriles
into alicyclic imino-compounds ; pre-
liminary note, P., 17.
the preparation of methyl l:l-(li-
iriethylcyclopcntan-3:4-dione-2:5-di-
carboxylate, P., 94.

Thorpe, Joeehjn Field, the nomenclature
of imino-compounds and of com-
pounds exhibiting imino-amino-
isomerism. P., 309.
Thorpe, Jueelyn Field. See also Stanley

Hubert Best.
Thorpe, {Sir) Thomas Edxvard, note on
the detection of white or ordinary
phosjdiorns in the igniting composi-
tion of Incifcr matches, T., 440 ; P.,
73.
note on Dr. Scott's paper on the
molecular weight of tetraethylam-
monium bromide and the atomic
weight of carbon. P., 285.
Threlfall, Richard, appaiatus for experi-
ments at high temperatures and pres-
sures, and its application to the
study of carbon : a correction, P.,
153.
Tinkler, Chai'lcs Kenneth, the colour and
constitution of the alkvl iodides of
cyclic bases, T., 921 ; P.," 128.
Titherley, Arthur Walsh, and William
Longton'H.ic'k.s, labile isomerism among
the acylsalieylamide, acylhydroxy-
amine, and phenylbenzometoxazine
groups, T., 908; P., 95.
Titherley, Arthur JFctlsh, and {iMiss)
Eli-jabeth Worrall, the action of phos-
phorus pentuchloride on benzamide,
T., 1143; P., 150.
Tuck, William Bradshaw, the constitu-
tion of hydroxyazo-compounds. Part
II., T., 1809; P., 230.
Turner, William Ernest Stephen, a
possible intramolecular change in the
inactive phenylalkyloxyaeetic acids ;
preliminary note. P., 201.
Turner, William Ernest Stephen. See

also Alexander Findlay.
Tutin, Frank, isoamygdalin and the
resolution of its liepta-acetyl deriva-
tive, T., 663; P., 118.
Tutin, Frank, Frederic JFilliaui Caton,
and Archie Cecil Osborn Hann, syn-
theses in the epincphrhie series, T. ,
2113 ; P., 289.
Tutin, Frank, and Hubert William Bent-
ley Clewer, chemical examination of
eriodictyon. Part II., T., 81 ; P.,
12.
the constitution of chrysophanic acid
and of emodin ; preliminary note,
P., 200.
the constituents of Eumex Eckloni-
anm. P., 302.
Tutin, Frank. See also Marmaduke

BarrowclifF.
Twiss, Douglas Frank. See Thomas
Slater Price and Arthur Slater.

INDEX OF AUTHORS.

2283

Usher, Francis Lawry, the inllucnce of
non-electrolytes on the solubility of
carbon dioxide in water, P., 303 ; dis-
cussion, P., 303.

Vanstone, Eniest, the miscibility uf

solids, T., 590; P., 30.
Veley, Victor Herbert, the aftinit}' values
of tropine and its derivatives, T. , 1.
the affinity values of certain alkaloids,
T., 758; P., 115; di.scussion. P.,
116.
the rate of formation of azo-dorivatives
from benzenoid diamines, T., 1186 ;
P., 175.
Vodden, Leonard. See David Leonard
Chapman.

W.

Wade, John, and Horace Finnemore,
etliyl ether. Part I. The influence of
water and alcohol on its boiling point,
T., 1842; P., 236.

Wade, John, and Richard WilliamTILex-
riman, the correction of the specific
gravity of li([uids for the buoyancy of
air, T., 2174 ; P., 290.

Walker, James Wallccce, and Vernon K.
Krieble, the hydrolysis of amyg-
dalin by acids. Part I., T., 1369 ;
P., 203.
tlie amygdalins. Part I., T., 1437 ;
v.. 208.

Wallach, Otto. Sec William. Henry
Perkin, jun.

Walpole, George Stanley, a simple gas-
drying apparatus for use with a me-
chanical exhaust pump, P., 97.

Walpole, Geonje Stanley. See also
Gcorcjc Barger.

Watson, Edwin Roy, the relation be-
tween the chemical constitution of
monoazo-dyes and their fastness to
light, P., 224.

Watson, EdiciiiRoy, A. Chcxmlrn- Sirkar,
and Jatindra M. Dutta, the relation
between the chemical constitution of
monoazo-dyes and their fastness to
light, P., 290.

Watson, Herbert Edmeston. See Edward

Charles Cyril Baly.
Watt, Henry Edgar, the alkaloids of

Scn>-ri„ laii/olius, T., 466 ; P., 68.
Wechsler, El/can. See Arthur Lap-
worth.
Wedekind, Edgar, and Samuel Judd
Lewis, an-ilytical investigation of
zirconium metal, T. , 456 ; P., 60.

chlorine generated by potassium per-
manganate ; its preparation and
puritj', P., 59; discussion, P.,
59.
Weizmann, Charles. See [Miss) Dorothy

Harrop.
Whitby, George Stafford. See Gilbert

Thomas Morgan.
Whiteley, (Miss) Martha Annie, and

Harold Mountain, studies in the bar-

bituri(! acid series. Part II. 1:3-Di-

phenyl-2-thiobarbituric acid and some

coloured derivatives. P., 121.
Wilks, William Arthur Reginald. See

Henry John Horstman Fenton.
Winmill, Tlmnias Field. See John

Theodore Hewitt.
Wise, Archibald. See Harold Hibbert.
Wood, John Kcrfoot, and (Miss) Emma

A!i\candrv Anderson, the constitution

of the salts of barljituric acid, T. , 979;

P., 154.
Woodhouse, John Obins. See William

Rohi'vt Lang.
Wootton, William Ord, amides and

imides of camphoric acid ; preliminary

note. P.. 308.
Worrall. (Miss) Elizabeth. See Arthur

W'dsh Titherley.
Wren, Henry, some derivatives of ?-benz-
oin, T., 1583; P., 219.

racemisation phenomena observed in
the study of /-benzoin and its deriva-
tives, T., 1593; P., 219.
Wiinsch, Donald Frrderick Sandys. See

Frederick Daniel Chattaway.

Y.

Yates, Josc2}h. See Robert Howson
Pickard.

INDEX OF SUBJECTS.

TRANSACTIONS AND PROCEEDINGS. 1909.

(Marked T. aiitl P. respectively.)

Single organic compounds of known empirical formula will be found in the
Formula Index, p. 2247.

A.

Acetanilides, primary interaction of

chloiine and (OiiTO.v and Jones), T.,

14.56; P., 196.
Acetylation, acids as accelerators in

(Smith and Okton), T., 1060; P.,

166.
Acid chlorides, action of mercaptans on

(Jones and Tasker), T., 1904; P.,

247 ; (Tasker and Jones), T., 1910 ;

P., 247.
Acids and bases, the relation between
the strength of, and the quantitative
distribution of affinity in the mole-
cule (Fi.tJRSCHEiM), T., 718; P.,
22; Part II., P., 193.

as accelerators in acetylation (Smith
and Orton), T., 1060 ; P., 166.

containing two adjacent ethenoid
groups, optical activity of (HiL-
DiTCH), T., 1570 ; P., 214.

influence of various sodium salts on
the solubility of sparingly soluble
(Philip and Garner), T., 1466 ;
P., 212.
Acids, aromatic, sulphinic, isolation of
(Thomas), T., 342; P., 60.

fattv, monobasic, azoimides of (FoRS-
TER and MtTLLER), T., 191 ; P., 26.

fatty, dibasic, optical activity of (HlL-
ditch), T., 1578; P., 214.

mineral, variation in the catalytic
activity of, with changes in their
concentration (Lapworth), P., 19.

organic, action of sulphur monochlor-
ide on salts of (a convenient method
of preparing anhydrides) (Denham),
T., 1235; P., 179.

See also Alkyloxy-acids and Hydroxy-
acids.
Acrylic acids, substituted, esterification

constants of (Sudbouough and

GiTTiNs), T., 315 ; P., 31 ; (Sud-

BOROUGH and Davis), T., 975 ; P.,

147.

Acylanilides, chlorination and bromin-
ation of (Orton and JoNEs), P., 233,
305.
Acylbornylaminea (Frankland and

Baurow), T., 2017, 2026 ; P., 263.
Adsorption in relation to Gibbs's theory
the mercury adsorbing surface (Lewis),
P., 258.
Afi-inity, Chemical: —
Affinity, quantitative distribution of,
in the molecule, ami the relation
between the strength of acids and
bases (FLiJRSCHEiM), T., 718 ; P.,
22; Part II., P., 193.
and electrons (Flurschkim), P.,

261.
of organic substances, simple method
for determining the (Hibbert),
P., 57 ; discussion. P., 58.
Affinity constants of hydroxy- and
alkyloxy-acids (Fixdlay, Turner,
and Owen), T., 938; P., 146.
Affinity values and hydrolysis, lecture
experiments to illustrate (Veley),
T., 759.
of certain alkaloids (Velky), T.,

758 ; P., 115.
of tropine and its derivatives
(Veley), T., 1.
Dynamic isomerism, studies of (Low-
RY and Desch), T., 807, 1340;
v., 13, 192.
benzyl sulphoxide ; a possible ex-
ample of (Smythe), T., 349.
Chemical dynamics of the reaction
between iodine and acetone
(Dawson and Leslie), T., 1860 ;
P., 246.
of the reactions between sodium
thiosulphate and organic halogen
compounds (Slator and Twis.s),
T., 93.
Chemical equilibrium between calcium
carbonate and carbonic acid, and
effect of dissolved salts on (Seyler
and Lloyd), T., 1347; P., 199.

2236

INDEX OF SUBJECTS.

Affinh V, Chemical : —
Dissociation equilibria in solutions,
method for investigatiug, aud its
application to the study of aqueous
jiotassium nicicuri-iodide solutions
(Dawson), T., 870 ; P., 129.
Hydrolysis and affinity values, lecture
experiments to illustrate (Veley),
T., 7:>9.
Velocity of chemical change, deter-
mination of the, by measurement of
the gases evolved (LAMrLouoH), P.,
23 ; discussion, P., 24.
Velocity of formation ofazo-derivatives
from lienzenoid diamines (Veley),
T., 1186; P., 175. •
Velocity of hydrolysis, influence of
hydroxy- and alkyloxy-groups on
the (FiNDLAY and Hickmans), T.,
1004 ; P., 152.
Velocity of reaction of triphenyl-
methane dyes with acid and alkali
(SiDfJWiCK' and Mooke), T., 889;
P., 123 ; (SiDGAViCK and PvIVETt),
T., 899 ; P., 124.
Alcohols, action of metallic calcium on
(Pekkin and Pkatt), T., 159 ; P.,
18.
racemic, resolution of (Pickard and
Kenyon), p., 167.
Aldehydes and ketones, condensation of,
with the sodium derivative of ethyl
cyanoacetate (Hawoeth), T., 480 ;
P., 76 ; (Gardner and Haavorth),
T., 1955 ; P., 250.
See also Hydroxyaldehydes.
Aldehyde-cyanohydrins, preparation of
acyl derivatives of (Francis and
Davis), T., 1403; P., 210.
Alkaloids, affinity values of certain
(Veley), T., 758; P., 115.
of SenecJo latifolius (Watt), T., 466 ;
P., 68.
Alkyl magnesium halides, and tertiary
amines, stability of compounds de-
rived from (Hibbert), P., 118.
Alkyloxy-acids, affinity constants of
(Findlay, Turner, and Owen), T.,
938 ; P., 146.
Allenecarboxylic acids, substituted, ex-
periments on (Lapworth and Wech-
sler), p., 307.
Aloins, constitution of the (Robinson
and Simonsen), T,, 1085 ; P., 76,
1.53.
Aluminium double and tri]i]e ferro-
cyanides with potassium and ammon-
ium (Robinson), T., 1353; P.,
195.
Amides, condensation of, with esters of
acetylenic acid.s (Ruhemann), T.,
984; P.. 87.

Amines, interaction of, with 2:3.5-<ri-
nitro-4-acetylaminophpnol (Mel-
DOLA and Hay), T., 1033 ; P., 167.
new method for the separation
of tertiary from secondary and
lirimary (Hibbert and Wise), P.,
119.
primary, secondary, and tertiary, es-
timation of (Sudrorough and Hib-
bert), T., 477 ; P., 75.
tertiary, and magnesium alkyl halides,
stability of compounds derived from
(HiBliERT), P., 118.
Amino-compounds, condensation of oxy-
methj'lenecamphor with (Pope and
Read), T., 171 ; P., 18.
Ammines, metallic, configuration of

(Baker), P., 223.
Ammonium, double and triple ferro-
cyanides of magnesium, aluminium,
and cerium with potassium and
(Robinson), T., 1353 ; P., 195.
Ammonium f/^c!lloroiodide and chloro-
bromoiodide (Chattaway), P.,
163.
chromate, r/Zchroraate, and /r/chroni-
ate, slow decomposition of, by heat
(Ball), T., 87.
^whalides (Chattaway), P., 163.
nitrite, decomposition and sublimation
of (Ray), T., 345 ; P., 56.
Amygdalins (Walker and Krieble),

T., 1437 ; P,, 208.
f/-Amyl group, influence of, in asym-
metric synfihesis (McKenzie and
MuLLER), T., 544; P., 88.
Androsin, CjjH^nOg.
Androsterol, CoqH^qO.
Anhydrides of organic acids, preparation
of (Denham), T., 1235; P.,
179.
preparation of, by the action of thionyl
chloride on salts of organic acids
(Denham), P., 294.
Anilides, quantitative decomposition of

(Davis), T., 1397 ; P,, 197.
Anilines, nitro-, mechanism of reduction

of (Flurscheim), p., 21.
Annual General Meeting, T., 611 ;

P., 101.
Antimony organic compounds (MacKey),
T., 604 ; P., 98; (Morgan, Mickle-
THWAiT, and Whitby), P., 302.
Apocynamarin, CogH-jgOg.
Apocynum aiulrdnaeiiiifoliiim^ constitu-
ents of the rhizome of (Moore), T.,
734; P., 85.
Apocynum cannabinum, constituents of

(Finnemore), p., 77.
Apparatus, gas-drying, for use with a
mechanical exhaust pump (W alpole),
p., 97.

INDEX OF SUBJECTS.

2237

Arsenic :—

Arsenious acid, some esters of (Lan(;

anil Wdoi.nnrsK), P., 199.
Arsenic organic compounds (Morgan
and MlCKLETiiWAiT), T., 1473 ; P.,
212.
Arsenic, estimation of, in organic
coiniiounds (Liitlk, Cahkn, and
Moiii;an), T., 1477 ; P., 212.
Association and viscosity in binary
mixtures of liijuids (Sentkii), P., 202.
Asymmetric compounds, study of (Kip-

i'iN(;), T., 408 ; P., T,.^..
Atomic volumes. See Volumes.
Atomic weight of carbon (.Scoit), T.,
1200; 1'., 173, 310; (Tuoui-E), P.,
285.
of chlorine (Gray and BruT), T.,
1633 ; P., 216.
Atomic weights, rejwrt of the Inter-
national Committee on, T., 2216.
table of, T., 2219
method of harmonising the (Moir),

T., 1752; P., 213.
of the lighter elements, divergence
of, from whole numbers (Eger-
Tox), T., 238 ; P., 26.
Availability of hydrogen cldoride in
alcoholic solution, influence of water
on the (Lapworth and Partington),
P., 307.
Azine series, studies in the (Hewitt,
Newman, and Winmill), T., 577 ;
P., 86.
Azo-oompounds, colour and constitution
of (Hewitt and Thoma.^), T., 1292;
P.. 190; (Hewitt and Thole), T.,
1393 ; P., 208.
Azo-componnds, hj-droxy-, constitution
of (Mitchki.l and Smith), T., 1430;
P., 209 ; (Tm-K), T., 1809 ; P., 230.
Azo-derivatives, rate of formation of,
from benzeuoid diamines (Veley), T. ,
1186; P., 175.
Azo-dyes, mono-, relation between the
chemical constitution and fiistness to
light of (Watson), P., 224; (Wat-
son, SiRKAR, and Dutta), P., 290.
Azoimide {hydrawic acid, Injilrttnitric
acid) sodium salt, interaction of benz-
hydroximic chloride and (Forster),
T., 184; P., 25.
Azoimides of monobasic aliphatic acids
(Forster and Muller). T., 191 ; P.,
26.

B.

Balance Sheets of the Chemical Society
and of the Research Fund. See
Annual General Meeting, T., 618 ; P.,
101.

XCV

Barbituric acid series, studies in the
(Whitei.ev and Mountain), P., 121.

Barium nitrite, molecular volume of
(Ray), T., 66.

Bases, and acids, relation between the
strength of, and the (|uantitativc dis-
triliution of aflinitv in tiie molecule
(FLiiii.sniEiM). T.. '718; P., 22, 193.

Bismuth ^n'oxide, solubility of, in alkali
hydroxides (Knox), t., 1760; P.,
226.
<?7'sulphide, solubility of, in alkali
sulphides (Knox), T., 1760 ; P.,
220.

Bleaching powder, a crystalline (Orton
and Jones), T., 751 ; P., 74.

Bornylamides (Kkankland and Bar-
row), T., 2017; P., 263; T., 2026;
P., 263.

Boron, preparation of (PRiNoaud Field-
ing), T., l.-.OO; P., 215.

Bromoacylaminobenzenes, action of
halogen acids on (OinoN and Jones),
P., 305.

Butter, detection of cocoanut oil in
(Caldwell and Hurtley), T., 861 ;
P., 73.

Butter-fat, cocoanut oil, and their fatty
acids, distillation of (Caldwell and
HriiTLEY), T., 853 ; P., 73.

C.

Caesium, new method for the detection

of (Ball), T., 2126 ; P., 284.
Calcium, action of alcohols on (Perkin

and Pu.\TT), T., 159 ; P., 18.
Calcium carbonate and carbonic acid,
equilibrium between, and effect of
dissolved salts on (Seyler and
Lloyd), T., 1347 ; P., 199.
hydride, action of, on alcohols (Per-
kin and Pp>att), T., 161 ; P., 18.
nitrite, molecular volume of (Ray),
T., 66.
Camphane series, studies in the (Fors-
ter and Thornley), T., 942 ; P., 145 ;
(Forster and Garland), T., 2051 ;
P., 244.
Carbamides, chlorine derivatives of sub-
stituted (Chattaway and Wunsoh),
T., 129; P., 11.
Carbon, atomic weight of (Scott), T.,
1200 ; P., 173, 310 ; (Thorpe), P.,
285.
apparatus for experiments at high
temperatures and pressures on
(Threlfall), p., 153.
Carbon f^i'oxide, tleconipo.sition of, by the
silent electric discharge (Holt), T.,
30.

7h

2238

INDEX OF SUBJECTS.

Carbon (//oxide, influence of non-electro-
Ivtes on the solubility of, in water
(.UsiiEu), P., o03.
Carbonic acid, constitution of
(Fkiend), r., 91.
and calcium carbonate, equilibrium
between, and effect of dissolved
salts on (Seyler and Lloyd), T..
1347 ; P., 199.
Carbonates, estimation of, in presence of
nitrites, sulphides or suljiliites, by
means of potassium dichromate
(Maule), T., 1491 ; P., 154.
studies of the (Seylek and Lloyd),
T., 1347 ; P., 199.
Carboxyl group, constitution of (Smed-

ley), T., 231 ; P., 16.
Cartbamine, C,5H]407.
Catecbol derivatives, methj-lene ethers,
action of phosphorus pentachloride on
(Ewixs), T., 1482; P., 210.
Cerium double and triple fenocyanides,
with potassium, sodium, and ammon-
ium (Robinson), T., 1353; P.,
195.
Cbemical constitution, and absorption
spectra, relation between (Baly,
Collie, and Watson), T.,
144.
and absorption spectra of pyridine
and derivatives, relation between
(Purvis), T., 294 ; P., 14.
and fastness to light of monoazo-
dyes, relation between (Watson),
P., 224 ; (Watson, Sirkar, and
Dutta), p., 290.
and optical properties of the aromatic
a- and 7-diketones (Smedley), T.,
218 ; P., 17.
and physiological action in the trope-
ines, relation between (Jowett
and Pyman), T., 1020 ; P., 165.
and viscosity, relation between
(Dunstan and Thole), T., 1556 ;
P., 219.
of the carboxyl group (Smedley),
T., 231 ; P., 16.
Cherry bark, wild. See Prunus

scrotiiui.
Chitin (C.,oH.,oOi<,X4)n.
Chlorine, atomic weight of (Gray and
BriiT), T., 1633; P., 216.
and hydrogen, interaction of (Chap-
man and MacMahc>n), T., 135,959,
1717 ; P., 15, 148, 224.
generated bj' potassium ]ierinanganate ;
its preparation and parity (Wede-
KIND and Lewi.s), P., 59 ; discus-
sion, P., .59.
jjrimary interaction of, and acetanil-
ides (Orton and Jones), T., 1456 ;
P., 196.

Chlorine : —

Hydrochloric acid {hijdrogrn chloride),
conductivity of, in various solvents
(Baly, Burke, and Marsden),
T., 1103.
density and compressibility of, and
adsorjitiou of, byeglass (Gray' and
Burt), T., 1634 ; P., 216.
influence of water on the availabil-
ity of, in alcoholic solution (Lap-
worth and Partington), P., 307.
Perchlorates, estimation of, by titan-
ous salts (Knecht), p., 229.
Chloroacylaminobenzenes, action of
halogen acids on (Orton and JoNEs),
P., 30.x
Chloroxylonine, CooHo:j07X.
Chrysoeriol, CigHi-jO^.
Cobaltinitrites, studies on the (Cunning-
ham and Perkin), T., 1562.
Cocoanut oil, butter fat, and their fatty
acids, distillation of (Caldwell and
HuRTLEY), T., 853; P., 73.
Colour and constitution of the alkyl iod-
ides of cyclic bases (Tinkler), T. ,
921 ; P., 128.
of azo-conipounds (Hewitt and
Thole), T., 1393 ; P., 208 ;
(Hewitt and Thomas), T., 1292 ;
P., 190.
of diazonium salts (Morgan and
Alcock), T., 1319 ; P., 202.
of aqueous solutions of violuric acid
(Donnan and Schneider), T., 956 ;
P., 148.
Colouring matters of cotton flowers,
Gonsypiuin hcrbarcum (Perkin), T. ,
2181 ; P.. 291.
Copper solutions, ammoniacal, nature of

(Dawson), T., 370 ; P., 3-3.
Copper carbonates and the cupricarbon-
ates (Pickering), T., 1409 ; P., 188.
sulphate, new basic (Pickering), T.,

1417.
sodium carbonates (Pickering), T.,

1418; P., 188.
Cupricarbonates (Pickering), T.,

1409 ; P., 188.
Cupric hj^droxide, electromotive be-
haviour of, in alkaline electrolytes
(Allmand), T., 2151 ; P., 2.58.
solubility of, in ammoniacal barium,
and sodium hydroxide .solutions
(Daw.son), T., 377 ; P., 33.
solubility of, in ammoniacal sulphate
.soiutions(DAWsoN),T.,370;P.,33.
Cuprous oxide, electromotive behavi-
our of, in alkaline electrolytes (All-
mand), T., 2151 ; P., 2.^.8.
Critical -solution point, infinence of, on
the shape of the melting-point curve
(Flam iiNF.R), T., 668 ; P., 71.

INDEX OF SUBJECTS.

2239

Cryoscopic experiments with two solutes
piesent to^'ether (Pattekson aiul
MOXTCO.MEUIE), T., 1138.

Crystallisation of i-xtenially compens-
ated mixtures (Kiiting and Pope),
T., 103; P., il.

Cupric and Cuprous salts. See under
Copper.

/.wCyanine dyes, optical and sensitising
jnopeitii's of (8iiEi'PAiU)), T., 15.

Cyanohydrins, condensation-s of (Mc-
CoMisiE and Parky), T., 584 ; P., 95.

Cyclic bases, colour and constitution of
alkyl iodides of (TiNKLEi;), T., 921 ;
1'., 128.

Cynotoxin, CooH^kjO,;.

Density {ajjecijic gravity) of liquids, cor-
rection of, for the buoyancy of air
(Waue and Merriman), T., 2174;
P., 290.

Diamines, benzenoid, rate of formation of
azo-derivatives from (Veley), T.,
1186 ; P., 175.

Diazoamino- compounds, constitution of
(F()i;sTEii and Garland), T., 2051 ;
P., 24-4.

Diazohydroxylamino-compounds, and the
influence of substituting groups on the
stability of their molecules (Gerhard
and Thompson), T., 767, 1115 ; P., 70,
149.

?>-Diazoimides, production of, from alkyl-
and aryl-sulphoiiyl-/)-diamines (Mor-
gan and Pickap>d), P., 300.

Diazonium ^erbromides or iV-^z-ibromo-
substituted hydrazines, preparation
and properties of (CIIArrA^VAY), T.,
862; P., 120.
salts, colour and constitution of (Mor-
gan and Alcock), T., 1319; P.,
• 202.

Dihydrobenzenes, substituted (Crossley
and Renoi-f), T., 930 ; P., 145.

a- and 7-Diketonea, aromatic, relation
between chemical constitution and
optical properties of (Smedi.ey), T.,
218; P., 17.

Diphenylamine ortho-sulphoxides, intra-
molecular rearrangement of (Barneti'
and Smiles), T., 1253 ; P., 74, 195.

Dissociation. See under Affinity, chemi-
cal.

Disulphides, preparation of (Price and
Twiss), T., 1050, 1489, 1725; P., 32,
165, 211, 232.

Dynamic isomerism. Sec under Affinity,
chemical.

E.

Echalliiiia Elaterium, constituents of the
fruit of (Power and Moore), T. , 1985 ;
P., 260.

ELlCriRdCllEMISTRY : —

Electrons and chemical affinity (Flur-
SCUEIM), P., 261.
elements and (Ramsay), T., 624 ;
P., 108.

Elements and electrons (Ra.msay), T.,
624; P., 108.
the lighter, divergence of the atomic
weights of, IVom whole numbers
(Egerton), T., 238 ; P., 26.

Emulsin, hydrolysis of amygdalin by
(Ai'LiO, T., 927 ; P., 62.

Enzymes. See Emulsin, Indimulsin.

Epinephrine series, syntheses in the
(TuTix, Caton, and Hann), T., 2113 ;
!'.. 289.

Equilibrium of sodium sulphite with
water (Hartley and Barrett), T.,
1178 ; P., 164.

Equilibrium, chemical. See under
Allinity, chemical.

Ergot, isolation and synthesis of j:?-hydr-
oxyphenj'lethylamine, an active prin-
ciple of (Bar.'jer), T., 1123 ; P., 162.

Eriodictyon, chemical examination of
(Ti-Tix and Clkwer), T., 81 ; P., 12.

Eriodonol, CiriHi^O-.

Esterification constants of substituted
acrylic acids (SuDHORoi;(iH and Git-
tins), T., 315 ; P., 31 ; (Sudrorough
and Davis), T., 975 ; P., 147.

Esters of organic acids, action of ethyl
carbamate on (Run em ANN and Priest-
ley), T., 449; P., 62.

Ethenoid groups, optical activitj' of acids
containing two adjacent (Hilditch),
T., 1570; p., 214.'

Ferric compounds. See under Iron.
Ferrocyanides. See Iron organic com-
pounds.

Gases, ignition-temperatures of (DixON

and Coward), T., 514 ; P., 67.
Glasses, formation of (Corb), P., 165.
Glazes, formation of (Cobb), P., 165.
Glucose derivatives, constitution of

(Irvine and Gilmoi-r), T., 1545 ; P.,

218.
Glucosides. See Androsiu, Gossypitrin,

Qnercimeritrin, /.soQuercitrin.
Glycide aryl ethers, action of ammonia

on iBdyd and Knowlton), T., 1802 ;

P., 235.

2240

INDEX OF SUBJECTS.

Gossypetin, CjsHioOg.
Gossypitrin. CoiHaiOjs. , , ,.

Grignard reagent, action of, on \)hthalu-
cster,s ^Shibata), T., 1449 ; P., 209.

H.

Halogen compounds, organic, the chem-
ical dynamics of the reactions between
sodium thiosulphate and (Slator and
Twiss), T., 93.
Halogens, action of, on aromatic hydr-
azines (Chattaway), T., 1065 ; P.,
147.
reactivity of the, in organic compounds
(Sexter), T., 1827^; P., 236.
Hantzsch-Werner hypothesis, an inter-
pretation of the (FoRSTER and Dunn),
T., 425 ; P., 68.
Hemp, Canadian. See Apocynum canna-

binni)!.
Heterocyclic compounds, formation of

(Le SrEUR), T.. 273: P., 36.
C)/rZoHexanone derivatives, formation of,
from olefinic compounds (Huhemann),
T., 109 ; P., 10.
Hibiscetin, from Hibiscus sabdariffa, and
its acetyl derivative (Perkin), T.,
1858 ; P., 248.
Hibiscus sabdariffa, colouring matters of
flowers of (Perkin), T., 1855; P.,
248.
Homoandrosterol, C27H44O.
Hydration of precipitates (Pickering),
T., 123 ; P., 12.
in solution and viscosity (DrNSTAN
and Thole), T., 1556 ; P., 219.
Hydrazine sulphate, preparation of, from
;)-urazine (Chattaway), T., 237 : P.,
11.
Hydrazines, aromatic, action of halogens
on (Chattaway), T., 1065; P.,
147.
A"-<rtbromo-suhstituted (diazonium
;;icrbromides), preparation and pro-
])erties of (Chattaway), T., 862;
P., 120.
Hydroacridines, formation of (Pope and

Howakb), p., 304.
Hydrochloric acid. See under Chlorine.
Hydrogen and chlorine, interaction of
^CirAi'MAN and MacMahon), T., 135,
959, 1717; P., 15, 148, 224.
Hydrogen chloride. See under Chlorine,
yyroxide, production of ozone in the
interaction between sulphur dioxide
and (Ferraboschi), P., 179.
Hydrolysis. See under Affinity,

'lifjniical.
Hydroxy-acids, affinity constants of
(FiNDL.w, Turner, and Owen), T.,
938; P., 146.

Hydroxyaldehydes, action of nitric acid

on the ethers of aromatic (Salway),

T., 1155; P., 160.
Hydroxyl derivatives, estimation of, in

mixtures of organic compounds (HlB-

hert), p., 57.

Ignition temperature. See under Ther-
mochemistry.
Imino-compounds, alicyclic, transforma-
tion of aliphatic nitriles into
(Thorpe), P., 17.
formation and reactions of (Best and
Thorpe), T., 8, 261, 685, 1506;
P., 28, 92, 216; (Thorpe), T.,
1901 ; P., 244.
nomenclature of (Thorpe), P., 309.
Indimulsin, the enzyme of indican, and
solul)ility of (Thomas, Bloxam, and
Perkin), T., 824; P., 126.
Iodides. See under Iodine and Poly-
iodides.
Iodine and acetone, dynamics of the re-
aelion between (Dawson and Leslie),
T., 1860; P., 246.
Iodine (dioxide, properties and reactions
of (Muir), T., 656; P., 88.
Iodides, alkyl, of cyclic bases, colour
and constitution of (Tinkler), T.,
921; P., 128.
Iron, action of steam on (Friend), P.,
90.
rusting of (Moody), P., 34. _ _
Ferric salts of aromatic sulphinic acids,
reactions of (Thomas), T., 343.
Iron organic compounds : —
Ferrocyanides, double and ti'iple, of
magnesium, aluminium, and cerium
with potassium and ammonium
(Robinson), T., 1353 ; P., 195.
Iron, estimation of, by permanganate in
the presence of hydrogen chloride
(Friend), T., 1228; P., 150.
ferrous, estimation of small quantities
of, by potassium permanganate in
the presence of hydrogen chloride
(Friend), P., 224.
Isomeric change and absorption spectra,
relation between (LoWRY and DesCH),
T., 807, 1340; P., 13, 192.
Isomerism, dynamic. See under Affinity,
chemical,
labile, among the acylsalicylamide,
acylhydroxyamine and phenylbenzo-
metoxazine groups (Titherley and
Hicks), T., 908; P., 95.

Ketimine-enamic isomerism (Thorpe),
P., 309.

INDEX OF SUBJECTS.

2241

Ketones ami aldehydes, condensation of,
with the sodiiun derivative of ethyl
cyanoacetiite (Hawohtii), T., 480 ; P.,
76; (Gaudner and Haworth), T.,
1955 ; P., 250.

Ketones, hydroaromatic (Crossley and
(llI.LIXG), T., 19.

Lead cohaltinitrite (Cunningham and
Perkin), T., 1569.
sulphate, solubility of, in concentrated
solutions of sodium ami jiotassiuin
acetates (Fox), T., 878 ; P., 128.
Liquids, correction of the specific gravity
of, for the buoyancv of air (Wade
and Merriman), T.", 2174 ; P., 290.
volume and temperature cliauges at-
tending mixture of (Patierson and
Montc.omerie), T., 1136.
Lithium nitrate, electrical conductivity
and absoiption spectra of, in various
solvents (Baly, Btrke, and Mars-
den), T., 1101 ; P., 144.

M.

Magnesium double and triple ferro-
cyanides with potassium and am-
monium (Robinson), T., 1353; P., 195.
Magnesium organic compounds : —
Magnesium alkyl halides and tertiary
amines, stability of compounds de-
rived from (Hiebert), p., 118.
Manganese sulphate and potassium per-
manganate, reaction between, in acid
solution (SiRKAK and Di'tta), P., 249.
Matches, lucifer, detection of white
phosphorus in the igniting composition
of (Thorpe), T., 440; P., 73.
Melting-point curve, influence of a
critical-solution point on the shape of
the (Flaschner), T., 668 ; P., 71.
Melting-point curves of mixtures of o-
and 7)-chloroacetanilides (Jones and
Ortox), T., 1059.
Memorial lectures, Gibbs (Clarke), T.,
1299; Mendeleetr (Tilden), T., 2077.
Mercaptans, action of, on acid chlorides
(Jones and Tasker), T., 1904; P.,
247 ; (Tasker and Jones), T., 1910 ;
P., 247.
Mercury, volumetric estimation of

(Knox), T., 1768; P., 227.
Metals, rapid electro-analytical deposi-
tion and separation of (Sand), P.,
228.
refractory, preparation at high tem-
peratures of, from their chlorides
(Pring and Fielding), T., 1497 ;
P., 215.

Molecular complexity in the liquid state

(lloi,Mi-,s an<i Sage.man), T., 1928.
Molecular volumes. See Volumes

iiiolccnlar.
Molybdenum, preparation of (Princ; and

Fiia.i.iN'c), T., 1504 ; P., 215.
Morphotropic relationshii>s between the
derivatives of picric acid (.Ikrusalkm),
T., 1275; P., 201.
Mustard oils, action of, on the ethyl
esters of malonic and cyanoacetic
acids (Ruhemann), T., 117 ; P., 14.
action of ethyl carbamate on (Ruhe-
mann and Priestley), T., 449 ;
P., 62.

N.

Naphthoic acids, optically active reduced
iPicKARD and Yates), T., 1011 ; P.,
152.
Nitrates. See under Nitrogen.
Nitriles, aliphatic, transformation of,
into alicylic imino-compounds

(Thoui-e), p., 17.
Nitrites. See under Nitrogen.
Nitrogen chloride (Chapman and Vod-
i»en), T., 138 ; P., 15.
Nitrates, absorption spectra of, in re-
lation to the ionic theory (Baly,
Burke, and Marsden), T., 1096 ;
P., 144.
Nitrites, action of carbon dioxide on

(Ma RLE), P., 74.
Nitrosyl chloride, action of mercaptans
on (Tasker and Jones), T., 1910 ;
P., 247.

Obituary notices : —

Bennett Hooper Brough, T., 2202.

Richard John Friswell, T., 2204.

William Ash well Sbenstone, T., 2206.

Edward Sonstadt, T., 2209.

Sir Thomas Stevenson, T., 2213.
Oleflnic compounds, formation of cyclo-

hexanone derivatives from (Ruhe-
mann), T., 109; P., 1.0.
Optical activity, properties, and Opti-
cally active compounds. See under

Photochemistry.
Organic compounds, reactivity of the

halogens in (Senter), T., 1827 ; P.,

236.
Oxazole derivatives, new synthesis of

(Robinson), T., 2167; P., 295.
Oxidation, atmospheric, of )3-methyl-

hydriiulone (Salway and Kipping),

T., 166; P., 16.
Oximino-group, configuration of the

(Mills and Bain), P., 177.
Oxydases (Gortner), P., 806.

2242

INDEX OF SUBJECTS.

Oxygen, oompressiLility of (Gray and
BiRT), T., 16o7; P., 216.
retarding efl'ect of, on rate of inter-
action of chlorine and hydrogen
(Chafman and MacMahon), T.,
959; P., 14?.
Ozone, prodnction of, in the interaction
lietween hydrogen dioxide and sulphur
dioxide (Ferraboschi), P., 179.

Perchlorates. See under Chlorine.
Phenol derivatives containing a mobile
uitro-group, syntheses with (Meldola
and Hay), T., 1033; P., 167.
Phenols, iodination of (Gardner and

HoPGSOx), T., 1819.
Phenols, nitro-, mechanism of reduction

of (FLfusrHElM), P., 21.
Phenylalkyloxyacetic acids, possible
intramolecular change in the inactive
(TuRNEii), P., 201.
Phosphorus, atomic volumes of
(Pkideaux), T., 445.
white or ordinary, detection of, in
igniting composition of lucifer
matches (Thorpe), T., 440; P.,
73.
Phosphorus pentahTomide, expansion of
(PiiiDEArx), T., 445.
Phosphoric acid, alkaloidal phenyl
yj-tolyl esters of (Luff and
Kipping), T., 2002.
electrical condueti^-ity of (Phillips),

T., 59.
isomeric derivatives of (Kipping and

Lt-ff), p., 203.
resolution of asymmetrical deriva-
tives of (Luff and Kipping), T.,
1993 ; P., 256.
Photochemistry :—

Photosensitive solutions, action of
/3-ravs on (Flaschner), T., 327 ;
P., 34.
Optical activity, effect of contiguous
unsaturated groups on (Hilditch),
T., 331, 1570, 1578 ; P., 29, 214.
Optically active compounds, effect
of solvents on the rotation of
(Patterson and McDx)nai,d),
T., 321; P., .36; (Patterson and
Montgomerie), T., 1128; P., 151.
Optically active substances containing
no asymmetric atom (Perkin,
Poi-E, and Wallach), T., 1789 ;
P., 230.
Optical properties of a- and 7-diketones
and chemical constitution, relation
between (.Smedley), T., 218; P.,
17.

Photochemistry : —

/3-Rays, action of, on photosensitive
solutions (Flaschner), T., 327 ;
P., 34.
Refractive power and chemical activity
of siilphur compounds, relation
between (Clarke and Smiles), T.,
992 ; P., 145.
Rotation ofopticalh' active compounds,
effect of solvents on (Patterson
and McDonald), T., 321 ; P., 36 ;
(Patterson and Montgo.merie),
T., 1128 ; P., 151.
Spectra, absorption, and chemical con-
stitution, relation between
(Baly, Collie, and Watson),
T., 144.
and constitution of pyridine and
derivatives, relation between
(Purvis), T., 294 ; P., 14.
and isomeric change, relationship
between (Lowrv and Desch),
T., 807, 1340; P., 13, 192.
of hydroxyazo - compounds and
quinonehydrazones (Tl'CK), T. ,
1809 ; P., 230.
of the nitrates in relation to the
ionic theory, and influence of
carbon dioxide on (Baly,
Burke, and Marsden), T.,
1096; P., 144.
of sulphonic derivatives of cam-
plior (Lowry and Desch).
T., 1340; P., 192.
Photosensitive solutions. See under

Photochemistry.
Phototropic compound, a new (Senieh

and Shepheakd), T., 441 ; P., 61. _
Phototropy and thermotropy, studies
in (Senier and Shepheard), T.,
1943 ; P., 246.
Phthalic esters, action of the Grignard
reagent on (Shibata), T., 1449; P.,
209.
Phycoerythrin, the pigment of the red
algse (Hanson), P., 117; discussion.
P., 117.
Physiological action and chemical con-
stitution in the tropeines, relation
between (.Iowett and Pyman), T.,
1020 ; P., 165.
Picrates, crystallography of (Jeru-

saI;EM), T., 1278.
Platinum organic compounds (Pope and

Peachey), T., 571 ; P., 96.
Potassium double and triple ferro-
cyanides with magnesium, aluminum,
and cerium and ammonium (Robin-
.son), T., 1353; P., 195.
Potassium acetate-potassium sulphate,
the system, at 25° (Fox), T., 885 :
P., 128.

INDEX OF SUBJECTS.

2243

Potassium (Z/clnomate, action of, on

carbonates, nitrites and mixtures of

carbonates and nitrites, carbonates

and sulpliitea, and carbonates and

sulphides (Maiilk),T., 1492; P., lo-l.

cobaltinitrite, composition of

(Cunningham and Pehkin), T.,

1567.

jucrmanganate and manganese sulphate,

reaction between, in acid solution

(SiRKAK and Dutta), P., 2-19.

mercuri-iodide solutions, study of

(Daw.son). T., 870 ; P., 129.
niercuri-iodidc containing camphor
of crystallisation (Mausii and
Sti!UTiiki!s\ T., 178S.
Polynitrophenols, constitution of, in
alkaline solution (Btttlk and
Mfavitt), T., 175.") ; P., 231.
Precipitates, hydration of (Pickeuino),

T., 123; P., 12.
Primus scrofina, constituents of bark of
(PcnvEi: and Moore), T., 213 : P., 27.
Pyridine compounds, relation between
constitution and absorption spectra of
(Puiivisl, T., 294 ; P., 14.
Pyridine bases, miscibility of, with
water, and intluence of a critical-
solution point on the shape of the
nielting-])oint curve (Flasciinei'.),
T., 068 ; P., 71.
Pyrones and allied compounds, relation
between absorption spectra and
chemical constitution of (Baly,
Collie, and Watson), T., 144.

ft.

Quercimeritrin, C.,, H.2,)0],j.
isoQuercitrin, C.^iilocPio-
woQuinoline derivatives (Pvman), T. .
1266, 17-38; P., 190, 230.

R.

Racemisation phenomena observed in
the study of Z-benzoin and its deriva-
tives (Wren), T., 1.593 ; P., 219.
Radium, table of products from
(Ram.say), T., 627.
emanation, litiuid and solid (Ciiay
and Ramsay), P., 82.
some physical properties of (Oray
and Ramsay), T., 1073 ; P., 161.
Rays. See under Photochemistry.
Refractive power. See under Photo-
chemistry.
Rotation. See under Photochemistry.
Rubidium, new method for the detection
of (Bali.), T., 2126; P., 284.

llame.c ecklonianmt, constituents of
(Ti-TiN and Clewer), P., 302.

Saponification. Sic Hydrolysis under

Atlinity, chemical.
Satinwood, Fast Indian {Chluroxylon
swidenid), chloroxylonine from
(Ai'LD), T., 964; 1'., 148.
Senecifolic acid, '"inirniOg.
Senecifolidine, Ci^^U.^-O^N.
Senecifoline, C|sI1._>76hN.
Senecifolinine, CgHnO.jX.
S' iiaid Idtifoliiis, alkaloids of (Watt),

T., 466; P., 68.
Silicates, foimation of (Cobb), P., 165.
SilicocWoroform, action of, on potassium

pyrnile (Reynolds), T., 508.
Silicon, ['reparation of (Princ; and
FiKi.DiNo), T., 1501 ; P., 21.'..
halides ami pyridine, acetunitrile, etc.
(Reynolds), T., .")12.
Silicon /'^Ydiromide, additive compounds
of, with pyridine, acetonitrile, and
propionitrilc (Reynolds), T., 513.
tdr(ic\\\ovi(\e, benzyl and ethyl deriva-
tives of (Martin and Kii'PINo),
T., 302; P., 27.
Silicon organic compounds (Kipping
and Davls), T., 69; P., 9;
CHEYXOLD.S), T., 50.'., .508, 512.
Silver, estimation of, in presence of

mercury (Knox), T., 1768 ; P., 227.
Silver cobaltinitrite (Cunninoham and

Perkin), T., 1568.
Sodium, new method for the detection of

(Ball), T., 2126; P., 284.
Sodium acetate-sodium sulphate deca-
hydrate, the system, at 25° (Fox),
T., 888 ; P., 128.
carbonate, spontaneous crystallisation
of solutions of (JoNES), T., 1672 ;
P., 213.
cobaltinitrite, preparation and com-
position of (CuNNiNoHA.M and
Perkin), T., 1568.
sulphite and its e<iuilibrium with
water (Hartley and Barrett),
T., 1178; P., 164.
thiosulphate, chemical dynamics of
the reactions lietween, and organic
halogen compounds (Slator and
Twiss), T., 93.
spontaneous crystallisation of solu-
tions of (Jones), T., 1672 ; P.,
213.
cerium ferrocyanide (Robinson), T.,

1359.
copper carbonates (Pickerino), T.,
1418; P., 188.

2244

INDEX OF SUBJECTS.

Solid solutions. Sec Solutions, solid.
Solids, tlio niiscibility of (solid soliUions)

(Vanstone), T., 590 ; P., 30.
Solubility of sparingly soluble acids,
influence of various sodium salts on
(Philip and Gauner), T., 1466; P.,
212.
Solution, hydration in, and viscosity
(DuN.STAN and Thole), T., 1556 ; P.,
219.
Solutions, contributions to the theory
of (Holmes and Sageman), T.,
1919; P., 231.
metliod for investigating dissociation
equilibria in, and its application to
tlie stud}' of aqueous potassium
niercuri-iodide solutions (Dawson),
T., 870; P., 129.
solid, of camphor and borneol, beuzil
and benzoin, and menthone and
menthol, physical properties of
(Vaxstoxe), T., 590 ; P., 30.
Solvents, influence of, on the rotation of
optical y active compounds (Patter-
son and McDonald), T., 321 ; P.,
36 ; (Patterson and Montgomerie\
T., 1128 ; P., 151.
Spectra. See under Photochemistry.
Steric hindrance, experiments with
secondary amines with reference to
(Meldola and Hay), T., 1037; P.,
167.
Steric influence, a study in (Davis),

T., 1397 ; P., 197.
Strontium nitrite, molecular volume of

(Ray), T., 66.
Styphnates, crystallography of (Jerusa-
lem), T., 1278.
Substance, 1.204,3803, from iodine
dioxide and sulphur trioxide (MuiR),
T., 660; P., 89.
Io05,2S03, from iodine pentoxide and
'sulphur trioxide (Muir), T., 662;
P., 89.
Sulphates. See under Sulphur.
Suh:hinic acids, aromatic, isolation of

(Thomas), T., 342; P., 60.
Sulphur : —
Thionyl chloride, action of mercap-
tans on (Tasker and Jones), T.,
1910 ; P., 247.
Sulphuryl cldoride, action of mercap-
tans on (Tasker ami Jones), T.,
1910; P., 247.
Sulphur woHochloride, action of, on
salts of organic acids (Denham),
T., 1235; P., 179.
dioxide, production of ozone in the
interaction between hydrogen per-
oxide and (Ferrahosciii), P., 179.
Sulphuric acid, constitution of
(Friend), P., 91.

Sulphur: —

Sulphurous acid, constitution of

(Fill END), p., 91.

Sulphates, volumetric estimation of
(Mitchell and Smith), T., 2198;
P., 291.
Sulphur organic compcunds, relation

Iietween rtifractive power and chemical

activity of (Clarke and Smiles), T.,

992; P., 145.
Synthesis, asymmetric, studies in

(McKenzie and Muller), T., 544;

P., 88; (McKenzie and Humphries),

T., 1105; P., 164.

T.

Temperature. See under Thermo-
chemistry.
Tephrosia purpurea, a glucoside from

(Clarke and Banerjee), P., 16.
Terpenes, cliemistry of (Henderson and

Agnew), T., 289 ; P., 35 ; (Hender-

.soN and Cameron), T., 969 ; P.,

151.
Thallium cobaltinitrite (Cunningham

and Perkin), T., 1569.
Thermochemistry : —

Heat of mixture of various liquids
(Patterson and Montgomerie),
T., 1136.

Temperatures, high, and high pres-
sures, apparatus for experiments at
(Threlfall), p., 153.

Ignition temperature of gases (Dixon
and Coward), T., 514 ; P., 67.
Thermotropy and phototropy, studies in

(Sexier and Shepheard), T., 1943;

P., 246.
Thespada lampas, colouring matters of

flowers of (Perkin), T., 1855; P.,

248.
Thiocarbamides, action of hydrogen

dioxide on (Barnett), P., 305.
Triazo-group, the (Forster), T., 184,

43i ; P., 25, 69; (For.ster and

Mi'LLER), T., 191, 2072; P., 26,

291.
Triphenylmethane dyes, rate of reaction

of, with acid and alkali (Sidcwick and

Moore), T., 889; P., 123; (Sidg-

wiCK and Rivett), T., 899 ; P., 124.
Tropeines, relation between chemical

constitution and pliysiological action

in tlie (JowETT and Pyman), T.,

1020 ; P., 165.
Tungsten, preparation of (Prino and
Fielding), T., 1502 ; P., 215.

volumetric estimation of (Knecht and
Hirbert), p., 227.
Tyrosinase, new variety of (Gortner),

P., 306.

INDEX OF SUBJECTS.

2245

u.

Unsaturated compounds, theory regard-
ing the coiitiguiatiuu of certain
(Bakei:), p., -i-iS.

Unsaturated groups, contiguous, ellect
ol', on optical activity (Hujutch), T.,
331, 1570, 157S ; P., 29, 214.

Vanadium, colorimetric estimation of
small quantities of (Grkgouy), P.,
232.
Vapour pressures, measm-ement of

(Cr.MMiNc), T., 1772; P., 237.
Velocity of hydrolysis. See under

Aliinity, chemical.
Violuric acid, thio-, group, coloured
salts and derivatives of the (ISHER-
\V()(id), p., 120.
Viscosity and association in binary
mixtures of liquids (Senteu), P.,
292.
and chemical constitution, relation
between (Duxstan and Thole), T.,
1556 ; P., 219.
and hydration in solution (Dunstan
and Thole), T., 1556 ; P., 219.

Volumes, atomic, of phosphorus (Pui-
DKAUx), T., 445.
molecular, of the nitrites of barium,
strontium, and calcium (Ray), T.,
66.

W.

Walden inversion, experiments on the

(McKknzie and Ci.oi'ch), T., 777 ;

P., 70.
Water, constitution of (Pickkrino), T.,

127.
Weights, correction of, of substances

weighed in air to weights in a vacuum

(Scott), P., 286.
Woods, irritant, examination of (Aui.d),

T., 964; P., 148.

X.

Xanthens, formation of (Pope and

II(i\VAi:n). P., 304.
Xanthoeridol, C^gll^fi-.

Z.

Zirconium metal, analytical investigation
of (Wedekind and Lewis), T., 456 ;
P., 60.

FORMULA INDEX.

Thr following index of organic compounds of known empirical formula is arranged
according to Richter's system (see. L>-T.ikon der Kdhlinstoff-Vcrhindungen).

The elements are given in the order C, H, 0, N, CI, Br, I, F, S, P, and the
remainder alphabetically.

The conijjounds are arranged —

Firstly, in groups according to the number of carbon atoms (thus C, group,
Co group, etc. ).

Secondly, according to the number of other elements besides carbon contained in
the molecule (thus 5 IV indicates that the molecule contains five carbon atoms and
four other elements).

Thirdly, according to the nature of the elements present in the molecule (given in
the above order).

Fourthly, according to the number of atoms of each single element (except carbon)
present in the molecule.

Simple metallic salts of acids are indexed under the respective acids.

Simple salts of bases (for example, liydrochlorides, platiuichlorides, and picrates),
when described for the purpose of further identifying the base, are indexed under
the latter.

Ci Group.

CHoOo Formic acid, constitution of (Friend), P., 91.

CH4O Methyl alcohol, viscosity-concentration curves for, and water (Di'xstan

and Thole), T., 1559 ; P., 219.
CH5N Methyl amine, preparation and crystallography of the styphnate (Jerxj-

.salem), T., 1285 ; cobaltiuitrite of (Cunningham and Pekkin), T., 1564.

1 III
CH4ON.. Carbamide, synthesis of ^)-urazine from (Ciiatt.\way), T., 235 ; P., 10.

1 IV

CHoONoCL Dichlorocarbamide, preparation of (Chattawav), T., 464;
"P., "72!'

Co Group.

C0H4O0 Acetic acid, action of sulphur nionociiloride on silver salt of (Denham),

T., 1238 ; P., 179 ; viscosity-concentration curves for, and water (Dunstan and

Thole), T., 1559 ; P., 219.
C.JH4BP., Ethylene dibromide, action of, on methylaniline (DuNLoi* and

Jones), T., 416; P., 61.
CoHflO Ethvl alcohol, visco-sity-concentration curves for, and water (Dtn-STAN

and Thole), T., 1559 ; P., 219.
C.2H7N Dime thy Limine, preparation and crystallography of the styphnate of

(Jerusalem), T., 1285.
Ethylamine, preparation of cobaltiuitrite of (Cunningham and Perkin), T.,

1565 ; preparation and crystallography of the styphnate of (Jerusalem), T.,

1287 ; condensation of dimethyldihydroresorcin with (Haas), T. , 421 ; P., 19.
CoOoCL Oxalvl chloride, action of mercaptans on (Jones and Tasker), T.,

"1904 : P., 247.

2247

2 III— 3 IV FORMULA INDEX.

2 III

C..H-.0<So Dithio-oxalic acid, ammonium, potassium, and potassium nickelo-

saIts"(.IoxES and Tasker), T., 1906 ; P., 160, 247.
CjHjO.iS Thio-oxalic acid, potassium salt (Jones and Tasker), P., 160.
C.H.OoBp Biomoacetic acid, interaction of, and its sodium .salt, with water

ruid with alkali (Senter), T., 1827 ; P., 236.
C.HjOjNj p-Urazine, synthesis from carbamide (Uhattaway), T., 235 ; P., 10.
CoH'.OCI Monochlovomethyl ether, syntheses with the aid of (SiMOKSEN and

Storey), T., 2106; P., 290.

2 IV
C..>H..,ON:iCl Triazoacetyl chloride (Forster and Muller), T., 200.
CoHjON.Cl. Methyltrichlorocarbamide (Chattaway and Wl'nsch), T.,
131.'

Cs Group.

C;iHf,0 Acetone, dynamics of the reaction between iodine and (Dawson and

Leslie), T.. 1860; P., 246 ; condensation of, with hippuric acid (Perkin and

SiMONSEN), P., 164.
CsHfiOo Propionic acid, action of sulphur rnonochloride on silver salt of

(D'enham), T., 1238.
C.iHfiO.-i '/-Lactic acid, asj^mmetric synthesis of (McKexzie and Mijller), T.,

54f).
CsHgO n-Propyl alcohol, viscosity-concentration curves for, and water (Dux-

STAX and Thole), T., 1559 ; P., 219.
CjHgN Trimethylamine, preparation and crystallography of the styphnate of

(Jerusalem), T., 1286.

3 III
C..,H40N.2 isolminazolone (Fenton and Wilks), T., 1329 ; P., 192.
CH-iOCl Epichlorohydrin, action of potassium hydroxide on, in presence of

monohydric phenols (Boyd and Marle), T., 1807 ; P., 235.
C3H50.)Bp a-Bromopropionic acid, interaction of, and its sodium salt, with

water and with alkali (Sexter), T., 1827 ; P., 236.
C3Hr,09N.> Glvceryl trinitrate (nitroglycerin), velocity of decomposition of, by

'heat"(R0BERTS0x), T., 1241 ; P., 179.
C3H7O0N Ethyl carbamate, action of, on esters of organic acids and thiocarb-

imides (Ruhemaxx and Priestley), T., 449 ; P., 62.
C..H,0,Sb Methyl antimonite (MAfKEv), T., 607 ; P., 98.
CaHitClPt Trimethylplatinic chloride (Pope and Peachey), T., 575.
CoHsIPt Trimethylplatinic iodide (Pope and Peachey), T., 571.
CsHioOPt Trimethylplatinic hydroxide (Pope and Peachey), T., 573.

3 IV
CiHsONoCls Ethyltrichlorocarbamide (Chattaway and WtJNSCH), T., 133.
C.fHsOoNoCl Acetylchlorocarbamide (Ch.a.ttaway and WtixscH), T., 129.
C3H0ON2CI0 Ethyldich'lorocarbamide (Chattaway and Wunsch), T., 132.
s-Dimethyldichlorocarbamide (Chattaway and Wuxsch), T., 131.
as-Dimethyldichl or 0 carbamide (Chattaway and Wunsch), T., 132.
CsHi'^NoIPt Diamrainotrimethylplatinic iodide (Pope and Peachey),

t.,"573.
C3H]sj04N2Cl2 8:9-Dichloro-7:10-dianilino-l:6-dihydroxynaphthacene-
qninone (Harrop, Norris, and Weizmaxx), T., 288.

2248

FORMULA INDEX. 4 II— 4 IV

d Group.

C4H..iN I'yri'ole, preparation of, anil action of Hilicocliloroform on the potassium

derivative i»f (Reynolds), T., 508.
CjHijOs o?-a-]\[cthylglycidic acid, potassium salt (Kay), T., 563; 1'., 90.
C4H6O6 Tartaric acid, snbstituted amides of (Jackson and Neville), P., 226;

resolution of the dl-acid (Kiri'iNi;), T., 412 ; P., 56.
C4H8O4 fif-a-Methylglyceric acid, conversion of (^/3-amino-a-hydroxyt»'<butyric

acid into, and potassium salt of (Kay), T., 560 ; P., 90.
C4HinO Ethyl ether, influence of water and alcohol on tlio boiling point of

(Wade and Finxemore), T., 1842 ; P., 236.
C4HnN Dicthylamine, cobaltiuitrite of (Cunningham and Pekkin), T., 1565

4 III

CiH.OiNo Tetraketopiperazine, reactions of (de Mouim'IED and Kii.e), T.,

549 ;" P., 71.
C4Hi04Nj Violuric acid, colour of aqueous solutions of (Donnan and

Schneidek), T., 956; P., 148.
C4H40jN.. Barbituric acid, constitution of tlie .salts of (Wood and Anderson),

T.', 9"79 ; P., 154.
CjHjO'iNs Triazoacetic anhydride (FoRSTEii and MiiLLEit), T., 201.
CjHi.OoNq Triazoethyl triazoacetate (Forster and Muli.ek), T., 200.
C4H,,0.jS.j Methyl dithio-oxalate (Jone.s and Taskek), T., 1906 ; P., 247.
C4H|;04S.j Substance, from action of sulphur raonochloride on silver acetate

(DexNHAm), T., 1238.
C4H70._,Na ^o-Triazobutyric acid (Foustek and Mulleu), T., 195.
C4H70..Br o-Bromobutyric acid, interaction of, and its sodium salt, with water

and with alkali (Sexteii), T., 1827 ; P., 236.
C4H70oN( o-Triazobutyric acid, and its silver salt, and resolution of (FoR.STER

and Muller), T., 193.
a-TriazoMobutyric acid, and its potassium and silver salts (For.steu and

Ml-ller), T., 196.
CjHtOjN Ethyl formylcarbamate (Ruiie.mann and Pkiestley), T., 454; P.,

62.
C4H70.,N,, Ureidomalonamide (Wood and Ander.son), T., 982 ; P., 154.
C4H7O iBP d-0-B r 0 m o-a-m ethyl-lactic acid {d-fi-broino-a-hi/droxi/isobiUyric acid

'(Kay), T., 562; P., 90.
C4HSON4 o- and ^o-Triazobutyramide (Forsteu and MIjller), T., 194.

o-Triazowobutyr amide (Forster and MiJLLER), T., 197.
CjHnOiiN (Z-3-Amino-a-hydroxywybutyric acid {d-a-methylisoscrinc), con-
version of, into t^a-methylglyceric acid (Kay), T., 560 ; P., 90.
C4H9NPt Triniethylplatinic cyanide (Poi-E and Peachey), T., 576.
C4HioOSi Diethylsilicoue (Martin and Kipi-ing), T., 313 ; P., 28.
C4Hio0.iCa Calcium ethoxide, and condensations by (Perkin and Pkatt), T.,

161; P., 18.
CjHinOjSa Dimethyl dithiodiglycollate, preparation of (Price and Twi.ss),

T., 1491 ; P., 211.

4 IV
CjHsO^jNiiS Thiovioluric acid, and its metallic salts (Isherwood), P., 120.
C4H6N2BP4Si Substance, from silicon tetrabromide and acetonitrile (Reynolds),
T.", 513.

2249

5 II— 6 II FORMULA INDEX.

Co Group.

C-.HsN Pyridine, relation between constitution <in(lal)sorption spectra of (Puiivis),

T., 294 ; P., 14.
C.,HtiO:! Dinietliylpyruvic acid (Pekkin and Simonsen), P., 164.
C-.HjoO-, a3-Diliydroxj'-7-niethoxvliut jMic acid, from oxidation of methyl

hevulose (IiiViNE and Hynd), T.,'1226 ; P., 176.
C-.HljN i'.wAmylamine, action of, on c/s-oiS-dibenzoylstyrene (Smedley), T., 220.

5 III
C.-,H,;OoNo Acetyl derivative of z'soiminazolone (Fexton and Wilks), T., 1332.
C,-,H70.jN Ethyl cyanoacetate, action of thiocarbimides on (Ruiiemann), T.,

117 : P., 14 ; condensation of .sodium derivative of, with ketones and aldehydes

(Haw-ii;th), T., 480 ; P., 76 ; (Gakdnek and Haworth), T., 1955 ; P., 250,
CHjiOoNj n-Triazo?sovaleric acid, and its silver salt (For.ster and Mullek), T.

198.
C.-,H90:!N Oxime of dimethylpyruvic acid (Perkin and Simonsen), P., 164.
C,-,HioON4 a-Triazowovaleramide (Forster and MiJLLER), T., 199.
CsHinO-.N.i Hydrazone of dimethylpyruvic acid (Perkin and Simonsen),

P., 164.

5 IV

C-.HvOjNS Ethyl thiocyanoacetate, preparation of (Ruhemann), T., 119.
CgH,oON.>Cl.. s-Diethyldichlorocarbamide (Chattaway and WiJNSCu), T.,
133."

Cg Group.

CfiHg Benzene, space formulaj for (Shibata), T., 1450 ; P., 209.

6 II

C,;H40j ^J-Benzoquinone, absorption spectra of, in the state of vapour and in

solution ; constitution of (Hartley and Leunard), T., 34.
CgHgOo Resorcinol, condensation of benzaldehyde with (Poi'E and Howard), P.,
30"4.
Quinol, absorption spectra of (Hartley and Leonard), T., 34.
CgHgO-- H y d r o X y m e t h V 1 f u r f u raid c h y d e, constitution of (Fenton and RoRlx-

SON), T., 1338.
C,;HgOH Dihydroxydiketoadipic acid (Ferraboschi), T., 1252; P., 178.
C,jH7N Aniline, cobaltinitrite of (Cunningham and Perkin), T., 1565.

a-Picoline, absorption spectra of, and of its hydrochloride (PuRVi.s), T., 296 ;

P., 14.
7-Picoline, preparation of (Flasciiner), T., 670.
C6H8O4 c?/cZoButaue-l:3-dicarboxylic acid, and some of its derivatives (Perkin

and Simonsen), T., 1166 ; P., 178.
CoH><N.2 Adi])onitrile, preparation of, and conversion into l-imino-2-cyanoc//c7o-
pentane (Thorpe), T., 1902; P., 244.
l-Imino-2-cyanoc//c^pentane (Best and Thori'e), T., 709; P., 93; forma-
tion of, from adiponitrile (Thorpe), T., 1903 ; P., 244,
Phenylhydrazine, action of potassium hypochlorite, and hypobromite, acetyl-
chloro-ainino-2:4-dichlor()ljenzeue, hypobromous acid, and bromine on (Chatta-
way), T., 1070 ; 1'., 147.
CfiHoN y3-methyl-j8-et]iylacrylonitrile (Gardner and Haworth), T., 1961.
CflHioO 2-Methylc;/c/opentan-l-one, preparation of (BEsxand Thorpe), T., 703 ;

P., 93.
CgHioOo /3-Metliyl-^-ethylacrylic acid (Gardner and Hawi.kiii), T., 1962.

2250

FORMULA INDEX. 6 II 6 III

CeHinOs Ethyl acetoacetate, action of monochloroiiiethyl ether on the sodium

derivative (Simonskx and Stokev), T., 2106 ; P., "290 ; anomalous viscosity of

(Thole), P., 198.
Propiouic anhydride, preparation of (Dkniiam), T., 1238 ; P., 179.
ChH]o04 Ethyl oxalate, action of Gri^'nard's reagent on (lNt;i,i,s and Mason),

P., 195.
Adipic acid, formation of l-phenylpyrrolidinc-2:.''i-(licarl)Oxylic acid fiom (Le

SuEuu), T.,273; P., 36.
Methoxy-j3-mothoxycroton ic acid, ami its silver salt (Simunsen and

Stoiiey), T., 2109.
ChHiiiOs Mucic acid, oxidation of, in presence of iron (Feimiaudsciii), T., 1248;

P., 178.
Saccharic acid, oxidation of, in presence of iron (Feuhabosciii), T., 1252;

P., 178.
CiHiiiOii, Diliydroxymueic acid (FEKitABO.scm), T., 1252; P., 178.
C,iHiiBP BromocycA'hexane, action of, on ethyl .sodiomalonate (IIote and

Pehkin), T., 1360; P., 207.
Ci.HijO,; Ethyl a-hydroxyisfdjutyrate, preparation of (Pauky), P-, 305.
C,;H|..0,; Glucose, mutarotatiou of, and its nitrogen derivatives (Gilmol'h), P.,

225.
CtjHisN Triethylaniine, preparation and crystallography of the picrate and

styphnate of (Jerusalem), T., 1281.

6 III

C,;HO-N, 2:3:5-Triuitroquiuoncdiazide (Meldola and Hay), T., 1383; P.,
208.

C^HNCl,; Hexachloro-a-picoline, absorption spectrum of (Pt.'uvis), T., 298.

C,;H..0,iN4 Dinitrohydroxyquiuonediazide, and its sodium derivative (Mel-
do la and Hay), T., 1384.

CfiRtOrN- Picric acid, morphotropic relationships between the derivatives of
(Jerusalem), T., 1275 ; P., 201.
2:3:5-Trinitropheno], preparation, prc^jcrties, and metallic derivatives of
(Meldola and Hay), T., 1382.

CHH-iOsN-j Trinitroresorcinol {sfij/Jmic aci'.f), crystallography of (Jei;usalem),
T.', 1278.

CHH4O7N4 2:3:5-Trinitro-4-aminophenol, preparation and properties of (Mel-
dola and Hay), T., 1378 ; P., 207.

CgH^OoN Nitrobenzene, reduction of (Peiikix and PuAir), T., 105 ; anomalous
viscosity of (Thole), P., 198.

CeHsOoCI Chloromethylfurfuraldehyde, new method of jjreparation of
'(Fenton and Robinson), T., 1339.

CgHsN.iCl Benzenediazonium chloride, determination of the rate of decom-
position of (Lamplough), p., 165.

CfiHsN.iBP-. Tribromophenylhydrazinc, preparation and jiropcrties of (Chat-
'ta'way), T., 865; P., 120.

CfiHoOoS Benzenesulphiuic acid, ferric salt, reactions of (Thomas), T., 343.

CfiHoNBP /J-Bromoaniline, cobaltinitrite of (Cunningham and Pekkin), T.,
1566.

CgHvON 2-Cvano'VtA']>eutau-l-one, and its .sodium dejivative (Best and
Thorpe), T., 709; P., 93.

CuH704BP-. a/85-Tribromobutane-j35-dicarboxylic acid (Pehkin and Simon-
sen), T., 1173.

C6H4O..N 5-Cyanovaleric acid, preparation of, and its silver salt (Best and
Thorpe), T., 710; P., 94.

C6H(,04Bp a-Bromobutane-j85-dicarboxvlic acid (Perkin and Simonsen),
T., 1174.

2251

6 III— 6 V FORMULA INDEX.

CgHioO.So Ethyl dithio-oxalate, preparation of (Jones and Taskek), T., 1905 ;

P. ,"247.
CfiHi,iOjS.i Substance, from action of sulphur monochloride on silver propionate

(Dknham), T., 1238.
CfiHiiON.s Semicarbazone of cyc^opentanone (Best and Thorpe), T., 702.
C^H„0,N Piperidylfornianilide (Ruhemanx), T., 119.
CsHnOoN;, Ethyl a- and Z-o-triazobutyrate (Forster and MuLLEU), T., 194.

Ethyl a-triazo«obutyrate (Forster and Muller), T., 197.
CfiHiiOyN) Semicarbazone of dimethylpyruvic acid (Perkin and Simon-

skn),'P., 164.
CgHisOsSb Ethyl antimonite (MacKey), T., 607 ; P., 98.

6 IV

CeHoOoNCl-i 2:3:4-Trichloropicolinic acid, absorption spectra of (Purvis),

T.', 299.
CeH.iON.iCL 2:3:4-Trichloropicoliuamide, absorption .spectrum of (Purvis),

'T., 29>s.
C6H3O3I3S 2:3:5-Tri-iodobenzenesulphonic acid (+ 3H.,0), and its metallic
salts (Boyle), T., 1713; P., 35.
2:4:5-Tri-iodobenzenesulphonic acid, and its metallic salts (Boyle), T.,

1715; P., 35.
3:4:5-Tri-iodobenzenesulphonic acid, and its metallic salts (Boyle), T.,
1710; P., 35.
C6H4O3I0S 2:4-Di-iodobenzenesulphonic acid, and its metallic salts (Boyle),
T., 1710; P., 35.
2:5-Di-iodobenzenesulphouic acid (and + 3HoO), and its metallic salts and

their solubilities (Boyle), T., 1701 ; P., 35.
3:4-Di-iodobenzenesulphonic acid (and + H.,0), and its metallic salts

(Boyle), T., 1695 ; P., 35.
3:5-Di-iodobenzenesulphonic acid, and its metallic salts (Boyle), T., 1704 ;
P., 35.
C^HjOalS Iodobenzene-?ii-sulphonic acid, sodium salt of (Boyle), T., 1694.
C*H50gNoNa3 Substance, from tetraketopiperazine and sodium ethoxide (de

MouiLPiED and Rule), T., 550 ; P., 71.
CeHisOjSPt.. Trimethylplatinic sulphate ( + 2H2O) (Pope and Peachey),
t., 575.

6 V
CeHoOiClIsS 2:3:5-Tri-iodobenzenesulphonyl chloride (Boyle), T., 1714.
2:4:5-Tri-iodobenzenesulphonyl chloride (Boyle), T., 1716.
3:4:5-Tri-iodobenzenesulphonyl chloride (Boyle), T., 1712.
CfiHaO.^ClLS 2:4-Di-iodobenzenesulphonyl chloride (Boyle), T., 1710.
2:5-Di-iodobenzenesulphonyl chloride (Boyle), T., 1703.
3:4-Di-iodobenzenesulphonyl chloride (Boyle), T., 1697. *

3:5-Di-iodobenzenesulphonyl chloride (Boyle), T., 1707.
CgHsOoClfLS 2:5-Di-iodobenzene-sulphonyl chloride dichloride (Boyle),

T.", l'70"4.
CeHsOjNlS Diazo-anhydride of iodoaniline-jj-sulphonic acid (Boyle),

T.', 1694.
CyH40.2Nl3S 2:3:5-Tri-iodobenzenesulphonamide (Boyle), T., 1714
2:4:5-Tri-iodobenzenesulphonamide (Boyle), T., 1716.
3:4:5-Tri-iodobenzenesulphonamide (Boyle), T., 1712.
CgH405NIS 5-Iodo-2-nitrobenzenesulphonic acid, potassium .salt of (Boyle),
T., 1700.

2252

FORMULA INDEX. 6 V 7 III

CiHsOjNLS 2:4-Di-ioaoben2enesuli)honanude (Boyle), T., 1710.

2:5-Di-ioclobenzenesuli)honamide (Boyle), T., 1704,

3:4-Di-iodobenzenesulphonamido (Boyle), T., 1697.

3:5-Di-iodobenze nesulphonaraide (Boyle), T., 1707.
CoHuOjNIS m-Iodoaiiiline-;;-sulphoiiic acid (Boyle), T., 1709.

jy-Iodoaiiilinc-o-sulphonic acid (Hovle), T., 1699.

C: Group.

C7H(iO Benzaldehyde, comlensation of resorciiiol with (Poi'E and Honvaud), P.,

304 ; oxidation of hydroxy-derivatives of (Dakin), P., 194.
CvH^O.) Benzoic acid, action of sulplmr inonochloride on sodium salt of

(Denham), T., 1237 ; P., 179.
C7H7N Methyleneaniline, action of, on /»-tolylthiocarbimide (Senier and

Shepheard), T., 505.

CvHyN Methylaniline, action of ethylene dibroniide on (Dunlop and Jones),
T., 416 ; P., 61.

?H-Toluidine, preparation and crystallography of the picrate of (JERUSALEM),

T., 1284.
7>Toluidine, cobaltinitrite of (CUNNIXCJIIAM and PeukIn), T., 1566.
CyHioOii cyc^oHexanone-S-carboxylic acid, synthesis of (DoHsoN, Ferns, and

Peiikin), T., 2010; P., 263.

C7H11N ;8-Methyl-;8-propylacrylonitrile (Gardner and Hawortii), T.,
1963.

3/3-Diethylacrylonitrile (Gardner and Haavorth), T., 1965.

C7H1..O 2:5-Diniethylc-!/cZopentan-l-one, preparation of (Best and Thorpe),

t., 705; P., 93.
2-Ethylc?/cZopentan-l-one (Best and Thorpe), T., 713; P., 93.
C7HioOn /3-Methyl-)3-propylacrylic acid (Gardner and Hawokth), T.,

1963.
C7H10O3 Ethyl dimethylpyruvate (Perkin and Simonsen), P., 164.
C7H1..O4 «-Methyladipic acid, formation of, from 5-cyanoliexoic acid (Best

and Thorpe), T., 712 ; P., 93.
Ethyl malonate, action of tliiocarbimides on (Ruhemann), T., 117 ; P., 14 ;

action of broinocyfZohexane and of 4-bromo-l-methylc(/f/c»hexane on the sodium

derivative of (Hope and Perkin), T., 1360 ; P., 207.
C7Hi;jBp 4-Bromo-l-methylcy(.'Zohex ane, action of, on ethyl sodiomalonate

(Hope and Perkin), T., 1360 ; P., 207.
C7H14O6 Methyl hevulose, and its derivatives (Irvine and Hynd), T., 1220 ;

P., 176.

7 III

C7H50.iN 3:4-Dihydroxybenzonitrile {protocatechuonitrile) (Ewins), T.,
14"88 ; P., 210. '

'^7H504N 4-Nitro-l:2-metliylenedioxybenzene, formation of, from piperonal
(Salway), T., 1163; (Perkin, PtOBiNsoN, and Thomas), T., 1980.

C7H5O5N 5-Nitro-l-hydroxy-2:3-methylenedioxybenzene (Salway), T.,
1161.

C7H5NS Phenylthiocarbimide, action of diphenylmethylenediamine om
(Senier and Shepheard), T., 498.

C7H6ON4 jo-Triazobenzaldoxime (Forster and Dunn), T., 430.
l-Hydroxy-5-phenyltetrazole (Forster), T., 186; P., 25.

C7H6OCI Benzhydroximic chloride, interaction of sodium azide and (Fors-
ter), T., 184; P., 25.

xcv. 2253 7 1

7 ni 8 II FORMULA INDEX.

C-H-ON Bonzamitle, action of pliosphorus peutacliloride on (Titiieri.ey and

'WoniiAU,), T., 1143; P., 150.
C7H7O5N Trihydroxypyridylacetic acid (Best and Thorpe), T., 1528.
CvHgO.jS o-Toluenesulphinic acid, ferric salt, reactions of (Thomas), T., 343.

jB-Toluenesulphinic acid, ferric salt, reactions of (Thomas), T., 344.
CtHsOjN.j Glutazylacetic acid (Best and Thorpe), T., 1528.
C-HyON 2-Cyano-2-niethylr;/cZ<)pentan-l-one (Best and Thorpe), T., 711 ;

"P., 93.
C-H10ON4 Semicarbazone of 2-cyanoc'!/t7upentan-l-one (Be.st and Thorpe),

T., 710.
C:Hi]0..>N 5-Cyanohexoic acid, and its silver salt (Best and Thorpe), T. 712.
C-HjiO^N 4-OxiniinocycZohexanecarboxyIic acid, optically active (Mills

and Bain), P., 177.
C7H13OJN3 Ethyl a-triazoisovalerate (Forster and Mlller), T., 198.

7 IV

C-H4O0NCI3 Methyl 2:3:4-trichloropicolinate, absorption spectrum of

(Purvis), T., 299.
C^HsONCI m-Chloroformanilide (Davis), T., 1398.
C7H7O0NS Nitrobenzvl mercaptan (0-, vi-, and p-), preparation of (Price

and Twiss), T., 1725 ; P., 232.
C7H70.>N3S Methanesulphonyl-2)-plienylenediazoimide (Morgan and

Pickard), p., 301.
C7H803SSe Benzyl selenosulphuric acid, potassium salt (Price and Jones),

T., 1729 ; P., 234.
C7H8O4NP Benzoylphosphamic acid (Titherley and Worrall), T., 1153 ;

P., 150.
C7H9N4KPt.2 Potassium trimethylplatinic platinocyanide (Pope and

Peache'y), T., 576.
C-H10O2N.7S Methanesulphonyl-^-phenylencdiamine (Morgan and Pick-
ard)," P., 301.

7 V

C7HSONCI3P a-Chlorobenzylidenephosphamic chloride (Titherley and

Worrall), T., 1149 ; P., 150.
C7H6O0NCLP Benzoylphosphamic chloride (Titherley and Worrall),

T.", 115"l ; P., 150.
C7H705NSSe Nitrobenzyl selenosulphuric acid (0-, 7/i-, and ju-), potassium

salts (Price and Jones), T., 1729 ; P., 234.

Ca Group.

CsHj.j l:l-Dimethvl-AV-c2/cZohexadiene, the so-called, of Harries and Antoni
(CfiOSSLEY and Renouf), T., 930 ; P., 145.

8 II
CgHyOi Benzoyl formaldehyde, refraction of (S medley), T., 218; P., 17.
CiiHfjOo Piperonal, action of nitric acid on (Salway'), T., 1163.
CgHfiOs 3:4-Dihydroxyphenylglyoxylic acid ( + H2O) (Baeger and EwiNs),

T., 560.
CgH(,0 Acetophenone, oxidation of hydroxy-derivatives of (Dakin), P., 194.
CgHB02 Pheuylacetic acid, action of sulphur monochloride on silver salt of

^Denham), T., 1239.

2254

FORMULA INDEX. 8 II

CsHjiOo Toluic acid {u-, m-, and />■), aclimi of siiljiliur iiioiioi'liluride on silver
salts of (Demi AM), T., 1239.

CsHsO;) Jlandclic acid, resolution of (Kli-riNi;), T., '114; P., iJ6 ; formation
of the f^-aciJ from amygdalin (Trns), T., 667; P., 118; asymmetric syn-
tliesis of the /-acid (McKenzif. and IIumphkies), T., 1105 ; P., 164.

CsH^O:; 4-IIydroxy-o-toluic acid, reduction of (HArDiscH, Hibbert, and
I'eukin), T,, 1870; P., 249.
G-Hydroxy-o-toluic acid, reduction of (BArnisrn und Pkkkin), T., 1883 :
P., 249.

ri-Hydroxy-?/(-toluic acid, reduction of (Mkuhu-.m and Pei:kix), T., 1889;
P., 249.

CsHwiOr, 3:4-l)ihydroxyniandeIic acid, and its salts (P>Aiif;EK and Ewi.\s\ T.,

557.
CHflN m-Aminostyrene, hydrochloride (Tuny, Caton, and Ham), T., 2125.
CsHyCl o-ChIoro-)8-phenylc thane, preparation of (Baugeii), T., 2194.
CsHinO.i Lactone of l-methyl-A'''-r//(7o-licxen-4-ol-2-carboxylic acid (Bau-

Discii, Hibbert, and Peukin), T., 1881.
CsHinOs m-Norpinic anhydride (Perkin and Simonsen), T., 117C.
CsHioO.> c)/i-/oHe.\ylideneacetic acid, formation of (Hope and Perkin), T.,
1366.
Lactone of CJ.s-l-methy l-c!/(Zohexan-2-ol-6-carl)oxylic acid (Bauijisch

and Pekkix), T., 1888.
Lactone of «s-l-methyl-c!/c/ohexan-3-ol-r)-carboxy lie acid (Meldrl'm and

Perkin), T., 1898 ; P., 249.
Dimethyldihydroresorcin, condensation of, with ethylamine (Haas), T.,
421 ; P., 19.
CsHioO^ Ethyl c;/c/opentanone-2-carboxy late, preparation of (Dobson,
Ferns, and Perkin), T., 2015.
l-Methylc!/c/ohexan-2-one-6-carboxylic acid (Baudisch and Perkin), T.,

1886.
l-Methylc(/r/ohexan-3-one-5-carboxylic acid (Meli)RU.m and Perkin), T.,

1899.
l-Methyl-A''-c!/):'/ohexen-4-ol-2-carboxylic acid (Baudisch, Hibbert, and
Perkin), T., 1882; P., 249.

CSH12O4 irans-'S ol•l^inic acid (Perkin and Si.monsen), T., 1177.

CsH,oOs Pentane-a5€-trjcarboxylic acid ( + iH.,0) (Duu.soN, Fern.s, and

Perkin), T., 2013.
CsH^O Methylheptenone, action of dehydrating and of oxidising agents

on (Crossley and Kenouf), T., 935.
CsHi40.2 ci/cZoHexylacetic acid (Hope and Perkin), T., 1364.
]|. CSH14O3 fZ-Amyl pyruvate (McKenzie and MiJLLER), T., 545.

■ l-Methyk2/cZohexan-2-ol-6-carboxylic acid (cis- and <ra/js-) (Baudisch and
K Perkin), T., 1887 ; P., 249.

B l-Methylc2/(.7ohexan-3-ol-5-carboxylic acid {cis- and trans-) (Meldru.m and

■ Perkin), T., 1897 ;. P., 249.

H l-Methvkj/cZohexan-4-ol-2-carboxylic acid {cis- and trans-, A and B)
^k (Baudlsch, Hibbert, and Perkin), T., 1877 ; P., 249.

^HC3Hi404 aS-Dimethyladipic acid, preparation of (Best and Thorpe), T., 707.
^™ o-Ethyladipic acid, foiination of, from 5-cyanoheptoic acid (Best and
Thorpe), T., 714 ; P., 93.
Ethyl methoxy-;8-methoxy-crotonate (SiMONSEN and Storey), T., 2109 ;
P., 290.
CSH14O5 Methoxymethyl methoxy-/8-methoxycrotonate (Simonsen and
Storey), T., 2110.

2255

8 II 3 III FORMULA INDEX.

CsHi^O,-, Ethyl tartrate, rotation of, in benzalJeliyde and in <iuinoline (Pat-
terson and McDonald), T., 321 ; P., 36; rotation of, and cr3'oscopic experi-
ments on (Patterson and JIontgomerie), T., 1130.

CnHifiOe Methyl methyl frnctoside (Ikvine and Hynd), T., 1227.

8 III

CsH.O;.N 3:4-Carbonyldioxybenzonitrile (Ewrxs), T., 1488; P., 210.
CsHO-.Cli 3:-l-I)ichloromethylencdioxybenzyl chloride (Ewins), T.,

"hS5'; p., 210.
CsHrO-tN 3:4-Methylenedioxyphenylglyoxylonitrile (Ewins), T., 1487;

P.', 210.
CjHrO-^Cl 3:4-Carbonyldioxybeuzy i chloride, preparation of (Ewins), T.,

"1485 ; P., 210.
C^H OsN4 2:3:5-Trinitro-4-acetylaminophenol, interaction of, with amines
(Mei.doi.a and Hay), T., 1033 ; P., 167 ; potassium and sodium salts (Meldola
and Hay), T., 1380.
C.H7ON f?-Benzaldehydecyanohydrin, synthesis of (Auld), T.,927 ; P., 62.
Indoxyl, condensations of, with aldehydes (Perkin and Thomas), T., 795 ; P.,
125 ; oxidation of solutions of (Thomas, Bloxam, and Perkin), T., 842 ; P.,
126.
CgHvOaCl rf-Phenylchloroacetic acid, preparation of, and conversion of, into
mixtures of r- and Z-mandelic acids, and r- and ^2)henylaminoacetic acids
(McKenzie and Clough), T., 782.
7-Phenylchloroacetic acid, conversion of, into mixtures of r- and d-, and r-
and Z-mandelie acids, and r- and d-, and r- and /-phenylaniinoacetic acids
(McKenzie and Clou(;h), T., 788 ; P., 70.
tu-Chloro-7>hydroxyacetophenone, preparation of (TuTiN, Caton, and
Hann), T., 2117.
C^H-OsN 5-Nitro-l-methoxy-2:3-methylenedioxybenzene (Salwa^; T.,

1161 ; P., 160.
C>.H70,;N:. 3:4:5-Trinitro-o-xylene (Crossley and Renoitf), T., 204.

3:4:6-Trinitro-o-xylene (Crossley and Renouf), T., 204.
CeHvNS i^'Tolylthiocarbimide, action of methyleneaniliiie on (Senieh and

Shepheard), T., 505.
C,HmON4 Triazoacetanilide (Forster and MOller), T., 201.
CsHgOjNo 3:4-Dinitro-o-xylene (Crossley and Renouf), T., 204.
3:5-I)initro-o-xylene (Crossley and Renouf), T., 204.
3:6-Dinitro-o-xylene (Crossley and Renouf), T., 204.
4:5-Dinitro-o-xylene (Crossley and Renouf), T., 204).
CgHjOrS 5-Sulpho-?/i-toluic acid ( + 2HoO), and its salts (Meldrum and

Perkin), T., 1893.
CsHyON Acetanilide, chlorination of (Jones and Orton), T., 1056 ; P., 146.
CgHyOaN Phenylaminoacetic acid {d- and Z-), action of nitrous acid on, and
conversion of, into phenyl-halogen-acetic acids (McKenzie and Clough), T.,
791.
(i-Mandelamide (Wren), T., 1583 ; P., 219.
3-Nitro-o-xylene (Crossley and Renoub-), T., 204.
4-Nitro-o-xylene (Crossley and Renouf), T., 204.

w-Amino-2)-hydroxyacetophenone (Tutin, Caton, and Hann), T., 2120 ;
P., 289.
C^H90-N 5-Amino-l-methoxy-2:3-methylenedioxybenzene, and its hydro-

cliioride (Salway), T., 1162.
C<,H»04N 4-Nitroveratrole, formation of, from vanillin methyl ether (Salway),
T., 1163.

2256

FORMULA INDEX. g nj g IV

CsH,„0>N.. p-Nitrophenylcthy lainiiio, ami its liydrochloride (Hai;(;ku and
Walpole), T., 1723.

CsHilOiBi*.' l:3-Dibioraonorpinic acid (Perkin and Simonsen), T. , 1177.
CsHiiON p-Hydroxyphonylethylamine, isolation and synthesis of (Hau-
gkr), T., 112:} ; P., Itj2 ; fiirthor syutlioses of (Bahuku and Wai.i-oi.k), T. ,
1720 ; P., 2:^9 ; and its liydioehlorido (Tutin, Caton, and IIann), T. , 2123.
2-Cyano-2:5-dimethyIc)/c7opentan-l-one (IJe.st and Thorpe), T., 706.
2-Cyano-2-ethylfi/t7opcntan-l-ono (Best and Thori'E), T., 713.

CsHuO.N o-Cyano-/3)3-diethylacrylic acid (Gardner and IIawukmi), T.,
1965.

y3-j[;-Dihydioxy-)9-iiheuylethyIainine, and its Iiydroeliloiide (TuTiN, Caton,

and Hanx), T., 2120 ; P., 289.
Senicifolinine, salts of (Watt), T., 473; P., 68.

CsHiiOjN 5-CyanobntylniaIonic acid, and its silver .salt (liEsT and Tiiori-e)
T., 70i.

CsHn04BP:, Methyl a)35-trilironio-butanc-j85-dicarboxylatc (Pekkin and
Simonsen), T., 1173.

CsHi.>0N4 Scmicarbazoiic of 2-cyauo-2-niethylc)/c7opon tan-1-onc (Best and
Thoupe), T., 711.

CjHjoOoBp.j l:4-Dibronio-l-niet]iyl'v/(7()liexano-2-carboxylic acid (Bau-
niscir, Hibbep.t, and Perkin), T., 1882.

CsHioOjBr.j Methyl a5-dibromoadipate (Le Sueur), T., 276 ; P., 36.
C^H|•^ON■. Semicarbazone of l-niethyl-A'w)/t7ohoxcu-3-one (Simonsen and
Storey), T., 2112.

CjHi.jOoN 5-Cyano-o-niethylhexoic acid, preparation of, and its silver salt
(Best and Thorpe), T. , 706.
5-Cyanoheptoic acid and its silver salt (Best and Thorpe), T., 713.

CsH,.)OoBp 4-Bromo-l-methyl(-3/rZohexanc-2-carboxylic acid {cis- and trans-
A) (Baudisch, Hibbep>t, and Perkin), T., 1878.
5-Bromo-l-methyk'!/c/f)hexane-3-car'joxylic acid (ris- and trails-) (Mei-
DRUM and Perkin), T., 1898.

(■is-6-Bromo-l-methylc?/cZohexane-2-carboxylic acid (Baudisch and Pi-r-
kin), T., 1889.

C^HiiOjN 3-Oximino-l-methy lc//cZohexane-5-carboxylic acid (Memiktm
and Perkin), T., 1900.

CHjjOoSo Propyl dithio-oxalate (Jones and Tasker), T., 1906 ; P., 247.
CSH14O4S0 o-Dithiodibutyric acid, preparation of (Price and Twiss), T.,
1052""; P., 165.
o-Dithiodi/sfjbutyric acid, i)rei)aration of (Price and Twiss), T., 1054 ; P
165. '

CsHisON Tropine, affinity values of, and its derivatives (Velev), T. , 1 ; con-
tiguration of (Barrowcliff and Ti'tin), T., 1966 ; P., 256.
i|/-Tropine, contiguratiou of (Barrowcliff and Tltin), T., 1966 ; P., 256.
CsHisON-; Semicarbazone of 2:5-dinic thylc!/c/opentan-l-one (Be.st and
Thorpe), T., 706.
Semicarbazone of 2-ethy lc(/cZopeutan-l-one (Best and Thorpe), T., 713.
CsHifiOgS Diethoxythioxan (Clarke and Smiles), T., 992; P., 145.
CsHoflNBP Tetraethylaramonium bromide, molecular weight of (Scon),
T., 1200 ; P., 173 ; (Thorpe), P., 285.

8 IV

C«HiO.,NCI.. 3:4-Dichloromethylenedioxybenzonitrile (EwiNs), T., 1487-
P.", 210"!

CsH„ONCL Acetylchloroamino-2:4-dichIorobenzene, action on phenyl-
hydrazine (Ch.vit.way), T., 1071 ; P., 147.

2257

8 IV -9 III FORMUl.A INDEX.

Cw!H604N.;Cl.j 3:r)-Dicliloro-l:6-diiiitro-o-xylone, |iroparatioii from i:6-iliiiiti-o-

o-.xyK'iiJ (Crossley and Renoi-f), T., 209.
CsHvONoCl, Bonzyltrichlorocarbamide (Chattaway and Wunsch), T.,

134.'
C,H70.;N.jCl Rcnzoylchlorocarbamidc (Chattaway and Wuxscii), T., 130.

2-Clilor(i-l-nitrosoacetanilide (Cain), T., 716; P., 123.
C.HrO.J.S Kthyl 2:3:5-tri-iodobeuzencsulphonato (Boyle), T., 1714.
C^H^ONCl Cliloroacotanilide, melting-point curves of mixtures of o- and ;>-

(Jones and Okton), T., 1059.
CsHsONoCL Benzyldichlorocarbamide (Chattaway and Wunsch), T., 134.
C.HsO.jNCl a-Cliloro-/3-;)-nitropheny]ethane (Bahger), T., 2196.
C.HAI.'S Ethyl 3:4-di-iodobenzenesulphonate (Boyle), T., 1698.
CsHgONoCl Benzylchlorocarbamide (Chattaway and Wunsch), T., 134.
2-Chloro-4-aminoacetanilide (Cain), T., 716; B., 123.

Cj Group.

CpHfiO.T 3:4-Metliylenedioxy plicny Iglyoxy 1 ic acid, preparation of (Bah-
ger and Evvins), T., 555.
CsHsOo Cinnamic acid, configuration of (IjAker), P., 223 ; halogen derivatives

of"(jAMEs and Sudborough), T., 1538 ; P., 211.
Phenyl methyl diketone, refraction of (Smedley), T., 218 ; P., 17.
Cr,Hs04 Myristicinaldeliyde, action of nitric acid on (Salway'), T., 1159 ;

P., 160 ; preparation of (Salway), T., 1208 ; P., 175.
CjiHgOs 3:4-Methy lenedioxymandelic acid, prepaiation of (Barger and

EwiNs), T., 554.
CHjoOa Phenylacetylcarbinol (Wren), T., 1592.
C.,H)oO-5 Phenylmethoxyacetic acid, affinity constant of (Findlay, Turner,

and Owen), T., 938 ; P., 146.
C9H10O0 a-Hydroxy-iS-phenylpropionic acid, affinity constant of (Findlay",

Turner, and Owen), T., 940 ; P., 146.
)3-Hydroxy-;8-phenylpropiouic acid, affinity constant of (Findlay',

Turner, and Owen), T., 941 ; P., 146.
Vanillin methyl ether, action of nitric acid on (Salway), T., 1163.
A cetovanillone {A-hyd7-o.ry-Z-methoxyacctuphenone), isolation of, from Apo-

cynum aiulrosacmifolium (Moore), T., 744 ; P., J^5.
C,HnN dMIydrindaraine, resolution of (Kipping), T., 413 ; P., 56.
CmH].>0 Ketone, from oxidation of terpinene (Henderson and Cameron), T.,

974 ; P., 151.
Cr,Hj40 l:l:5-Trimethyl-A^-c?/cMiexen-3-one {isophorunc); and some of its

homologues), synthesis of (Crossley' and Gilling), T., 19; preparation of

(Cros.sley and Gilling), P., 96.
C9H14O2 l-Meth)'k?/dohexylidene-4-acetic acid, resolution of (Perkin,

Pope, and Wallach), T., 1789.
CnHj404 cyc^Hexylmalonic acid, and its potassium salt (Hope and Perkin),

T., 1363.
€911,405 cisHydroxypinic acid, prejiaration of (Perkin and Simonsen), T.,

1175.

9 III

C.,H:;0:,C1,-, 3:4-Dichloromethylenedioxyphenyldichloroacetyl chlor-
ide (Barger and Ewins), T., 558.

C9H4O3CI4 3:4-Dichloromethylenedioxyi)henylehloroacetyl chloride
(Barger and Ewin.s), T., 556.

2258

I

FoliMTLA INDEX. 9 HI

C<,H40jClo 3:4-C'aiboiiy Idioxyplienylch loiDiicety 1 chloride (Barger and

KwiNs), T., 557.
CgH^O-.Cl) 3:4-Carboiiy lclio.\-y])lien vldicliloroacetic acid (I?auo?:k and

Ewiss), T., 559.
C.,H,0,C1 3:4-Carboiiy ldio.\ vpheii V Icliloioacetic acid (Bargkr and

KwiNs), T., 556.
CHvON Cinnamonylcarbi iiiido {cinnamcnijl i80cyrt?(rt^e) (Forstkr), T. , 433 ;

P., t)0.
CiHvON-! r'innamovlazoiniide, and transformation of, into cinnamenyl larb-

imide (Forster),'T., 433 ; P., 69.
C.HtO.N Indoxylic acid (Perkin), T., 847 ; P., 126.
CH^OiCl Myiisticinoyl chloride (Salway), T., 1161.
C,,HtO,,N Nitromyristicinaldehyde (Salway), T., 1160; P., 160.
C,,HAN Nitroniyristicinic acid (Salway), T., 1165.
C;)HmOoBp.j o;8-Dibronio-j3-i)henylpropionic acid, action of orj^anic bases on

(James and Sudboroi-gii), T., 1543.
C(,Hj|0._.N Aiiisaldeliydccyanohydrin, jireparation of, and action of hydrogen

chloride on (McCombie and Parry), T., 584 ; P., 95.
CqHaOjN Ilippuric acid, condensation with acetone (Perkin and Simonsen),

P., 164.
C;iHn04N Lactouo of ethyl hydrogen a-cy ano-3-hyd roxy-aj3-hydro-

muconate (Best and Thorpe), T., 1524.
3:4-MethyIenedioxyniandelaniide (Baruer and Ewins), T., 555.
Myristicinamide ( + H.jO) (Salway), T., 1161.
CgHinOBPo aj3-Dibroino-2)-methoxy-o-phenylctliano (Trrix, Caton, and

Hann), T., 2124.
CyHioOoN., 5-Nitrosoaceto-o-toluidide (Cain), T., 715 ; P., 123.
6-Nitrosoaceto-??i-toIuidide (Cain), T., 715 ; P., 123.
2-Xitrosoaceto-2'-tolaidide (Cain), T., 715; P., 123.

CsHioO.jNo Ethyl 2-ketotetrahydropyrrolidene-5-cyanoacetatc, and its
sodium, potassium and silver salts (Best and Thorpe), T., 1532.
Ethyl-2-ketodihydroi5opyrrolyl-5-cvanoacetate (Best and Thorpe), T.,
1533.

CgHiiON Base, from interaction of ;3-bromo-a-hydroxy-jj-methoxy-o-phenylethane

and ammonia (Tutin, Caton, and Hann), T. , 2125.
CgHiiCNi Ethyl 2-iminotetrahydro-pyrrolidene-5-cyanoacetate (Best

and Thorpe), T., 1530.
CuHiiOsN Ethyl 5-cyanor2/c/opentan-l-onp-2-carboxylate, and its potassium

anil silver derivatives, and etliylation of (Best and Thorpe), T., 701 ; P., 92.
CaHnOjN Ethyl hydrogen a-cyauo-/3-ketoadipate, and its silver .salt (Be.st

and Thorpe), T., 1.524.
C.,Hi.,OoN.T Ethyl 2-imino-3-cyanoc!/c/opentane-l-carboxylate (Thorpe),

f'.,"l8; (Best and Thorpe), T., 696 ; P., 93.
CflHj-.OjNo Ethyl hydrogen /8-imino-a-cyanoadipate, and its silver salt

('P.est and Thorpe), T., 1534.
C.|H]-iON ^-A[ethoxyphenylethylamine, and its hydrochloride (Barger and

\Valpole), T., 1724; P., 229.
CqHj!04N 5-Cyanomethylbutylmalonic acid, and its silver salt (Be.st and

Thokpe), T., 706,
C:,Hi304Bp a-Bromoc//c/ohexylraalonic acid (Hope and Perkin), T., 1364.

c/sBromopinic acid (Perkin and Simonsen), T., 1175.
C9H14ON4 Semicarbazone of 2-cyano-2:5-dimethylcycZopentan-l-one

(Be,st and Thorpe), T., 706.
Semicarbazone of 2-cyano-2-ethylcyc/opcntan-l-one (Be.st and Thorpe),

T., 713.

2259

9III-I0II FORMUl.A INDEX.

CqHi.sON Oxime of l:l:5-t iimothyl-A-'-c?/(7ohexen-3-ono (Crossley and

" Gii.i.iNo\ T., 25.
C.iHi.-.O^N-i Semicarbazone of l-methylc2/c/ohexaii-2-one-6-carboxylic

acid (Raudisch and Pkrkin), T., 1837.
CgH-iiOaSb Propyl antimonite (MacKey), T., 607 : P., 98.

9 IV
CgHioONCl wi-Chloropropionaiiilidc, (Davis), T., 1398.
CoHnONgSo Anhydrodiallyldithinbiuretcarboxylie acid (Ruhemann

and Priestley), T., 4.56.
CHioOClBr a-Chloro-3-bromo-^;-inetlioxy-o-plicuylethane (Tl'TlN, Caton,

and Hann), T., 2124.
CHjiOsNoNa.i Substance, from tetraketopiiierazinc and sodium amyloxide (he

MoriLriEi) and Rule), T., 550 ; P., 71.

Cio Group.

CjnHs Kapbtlialcnp, combustion of, and the atomic wniglit of catbon (Scott),

P., ;'.10.
C10H16 liimonene, action of chromyl clilDride on (Henderson and Cameron),
T., 969; P., 151.
Pinene, oxidation of, with mercuric acetate (Henderson and AGNE^v), T., 289 ;
P., 357 ; conversion of, into sobrerol (Henderson and Eastburn), T., 1465 ;
P., 211.
Terpinene, action of chromyl cliloridc on (Henderson and Cameron), T. ,
969; P., 151.

10 II

CioHgOv Cotarnic acid, synthesis of (Perkin, Robinson, and Thomas), T.,

1977; P., 262.
CioHioO ;3-Methylhydrindone, oxidation of (Salway and Kippino), T., 166;

P., 16.
CioHjoOa a-Benzoylpropionic acid (Hope and Pekkin), T., 2045.
CinHio04 Z-Acetylmandelic acid ( + H.p), hydrolysis of (McKenzie and

Humphries), T., 1106.
CioHjoNo )3-Imino-a-cyano-7-phenylpropane, preparation of, and formation of

l:3-naphthylenediamine from (P»est and Thorpe), T., 8.
1:3-Naphthylenediamine, formation from jS-imino-a-cyano-y-phenylpropane

(Best and Thorpe), T., 8.
C]oHi20 o-j>Tolylpropaldehyde, isolation of, from terpinene (Henderson and

Cameron), T., 973; P., 151.
CjoHisOo Glycide o-tolyl ether (Boyd and Knowlton), T., 1802 ; P., 235.
/3-Phenyl-u-meth}'lpropionic acid, resolution of, and rotatory power of the
■ (Z-acid (Pickard and Yates), T., 1019 ; P., 152.
CioHijO.-i Acetyl derivative of a-p-dihydroxy-a-phenylethane (Tutin,

Caton, and Hann), T., 2124.
Phenylethoxyacetic acid, affinity constant of (Findlay, Turner, and

Owen), T., 939 ; P., 116.
C10H12O5 Ethyl 3:4-dihydroxymandelate (Barger and Ewins), T., 558.
Trimethylgallic acid, occurrence in nature of, and .silver salt (Power and

Moore), T., 254.
CioHiaN rf^Methylhydrindamine, resolution of (Kipping), T., 411 ; P., 55.
CioHiiO-. Camphoric anhydride, new method of preparing (Edgerton), P.,

149.

2260

FORMULA INDEX. 10 H- 10 III

C10H14I3 Di-iodocamphor (Maush and Stuutheks), T., 1786.

CioHigN a-DimethyIamino-i9-phenylethano (Bakger), T., 2195.

CmHifiO l:l-DimethYl-5-ethyI-A^-c//(7ohexen-3-oiie (Ckossley and (Jilm.nt,),
T., 28.
Camphor, absorption spectra of halogen, nitre-, and methyl derivatives of
(LowKY and I)Escir), T., 807 ; P., 13; absorption spectra of snlphonic deriv-
atives of (LowKY and DEsni), T., I.'J-IO ; P., 192 ; physical properties of .solid
solutions of, and borucol (Vanstone), T., r>95 ; P., 30 ; mercury derivatives of
(Marsh and Struthers), T., 1777 ; P., 228.

CinHigO.j 8-Hydro.xycarvotanaeetone, preiiaration of, from pinene (Hender-
soN^and Acnew), T., 292 ; P., 35.

CinHigO', Ethyl l-metliylc!/c/ohe,\an-3-one-5-carbo.\ylatc (Mkldrum and
Perkin), T., 1899.
Pinonic acid, preparation of (Pei;kin and Si.mon.sen), T., 1171.

C10H16O4 l-Methylcyc/ohexyl-'l-malonic acid, and its potassium salt (Hope
and Perkin), T., 1367.
Camphoric acid, amides and iniides of (Wootton), P., 308.

CioHihO^, l-MetliyI(.-i/t'/ohexyI-4-tartronic acid, and its barium salt (IIorE and
Perkin), T., 1368.

C|„Hir,0,i S en eci folic acid, and its silver salt (Watt), T., 172 ; P., 68.

CiflHnN )8-MetIiyl-y3-hexyIacryioni tril e (Gardner and Hawortii), T.,
1964.

CinHisO Borneo), physical properties of solid solutions of, and camphor (Van-
stone), T., 595; P., 30.
Mcnthone, physical properties of .solid solutions of, and menthol (Vanstone),
T., 602 ; P., 30.

CinHigOo /3-Methyl-;8-hexylacrylic acid ((Jaruner and Haworth), T.,
1 964.
Sobrerol, preparation from pinene (Henderson and Aonew), T., 291 ; P., 35 ;
conversion of pinene into (Henderson and Eastburn), T. , 1465 ; P., 211.

C]oH.>oO Menthol, physical properties of solid solutions of, and menthone (Van-
stone), T., 602 ; P., 30.

CioHiioOg Tetramethyl hcvulose, preparation of, from methyl methylfructoside
(Irvine and Hynu), T., 1227.

10 III

CinHvOsN 7-Nitro.5:6-methylpnedioxy-l-hydrindono (Pehkin, Robinson,

and Thomas), T., 19S1.
CinHgOiS u-NaphthalenesuIphinic acid, ferric salt, reactions of (Thomas),

T., 344.
/3-Naphthaleuesulphinic acid, ferric salt, reactions of (Thoma.s), T , 344.
CioHsOtNo a!-2(6)-Dinitro-3-methoxy-4:5-methylenedioxystyrene (Sal-

AVAY), T., 1214.
CioHoON Cinnamaldehydecyanohydrin, action of hytlrogen chloride on

(McCoMBiE and Parry), T., 584 ; P., 95.
CinHftOBP Bromo-)3-methylhydrindone (Salway and KipriNo), T., 170.
CioHr.OsN 7-Amino-5:6-methylenedioxy-I-hydrindone (Perkin, Robinson,

and Thomas), T., 1982.
CinHoOsCl ;^-Hydroxyacetophenone chloroacetate (Tutin, Caton, and

Hann), T., 2117.
a!-Chloro-/>-acetoxyacetophenone (Tutin, Caton, and Hann), T., 2119.
C10H9O4N 3:4-Methylenedioxyphenylglyoxylmethylamide (Barger and

EwiNs), T., 556.
CioHgOfiN Lactone of trihydroxycarbethoxy pyridylacetic acid (Best

and Thorpe), T., 1527.

2261

10 III 10 IV FOEMULA INDEX.

CioHioO',No Lactam of carbc thoxyglutazy lacetic acid (Br.i^T and
TiioKrE), T., 1526.

CioHnOCl rf-)3-Phenyl-o-niethylliropionyl chloride (d-benzylmdhylacetyl
chhiridc), preparation of (Pickakd and Yates), T., 1019.

CioHnOoCl i)-Methoxyphenylpropionyl chloride (Bakcer and Walpole),
T.,"l724.

CinHioONo Acetyl-;)-nitrophenvlethylaminc (Bakger and Walpole), T.,
iri-jfP., 229.
Ethyl 2-k e t o-l-m e t h y 1 1 e t r a li y d r o ]> y r r o 1 i d e n e-5-cy a n o a c e t a t e (Best
anil Thorpe), T., 1535.

CioHjoOfiNo Carbethoxyglutazylacetic acid (Best and Thorpe), T., 1526.
Ethyl dihydrogen /3-imino-a-cyano-butane-a75-tricarboxy late, and its
silver salt (Best and Thorpe), T., 1523.

CjoHioOfiN^ 2:5-Dinitro-4-ac etylamino-3-dimethylaniinophenol, and its
silver salt (Meldola and Hay), T., 1048.

C10H13ON 2-i3-Methylaminoethyl-benzaldehyde (Pym.\n), T., 1749.

2-Methyl-3:4-dihydroi\soqninolinium hydroxide, salts of (Pyman), T.,
1749.

CjoHisO.^N ;)-Methoxvphenylpropionamide (Barger and Walpole), T.,
1724 ; P., 229.
3-Nitrodurene (Cain), P., 260.

CioHisOaNs Phenylacutylsemicarbazone (Wren), T., 1593.

CinHnO-iN Ethyl 5-cyano-5-methy lr?/c^opentan-l-one-2-carboxy late (Best
and Thorpe), T., 702; P., 93.
Ethyl 3-cyano-2-methoxy-A'--rycZopentene-l-carboxylate (Be.st and
Thorpe), T., 702.

CioH^O-iNo a-Dimethylamino-3-j;-nitrophenylethane, and its oxalate
(Baroer), T., 2195.

CioH]404N2 Ethyl hydrogen o-cyauo-j3-methyliminoadipate, and i!s
silver salt (Best and Thorpe), T., 1536.
Ethj4 )3-imino-a-cyanoglutarate, preparation of (Best and Thorpe), T.,
1518.

CioHi404Br., Methyl l:3-dibromo-norpi nat e (Perkin and Simonsen), T.,
1177.

CjoHisON Iminocamphor, aryl derivatives of (Forster and Thorxley), T.,
942; P., 145.
Hordenine, synthesis of (Barger), T., 2193 ; P., 289.

C10H15ON3 Semicarbazone of ketone from oxidation of terpinene (Hender-
son and Cameron), T., 974 ; P., 151.

CjnHjoOoN /3-Amino-;3'-o-tolyloxyzsopropyl alcohol, and its salts (Boyd and
Knowlton), T., 1804; P., 23^.

CirjHi504Bp a-Bromo-l-methvlr!/c?ohexyl-4-nialonic acid (Hope and Per-
kin j, T., 1367.

C,oHi,jO.,N., 4 -0 X i m i n o-5-e t h y 1 i m i n 0-1 : 1 -d i m e t h y Icycloh e x a n-3-o 11 e (and
-r2H.;0) (Haas). T., 423.

CioHie04BP2 Ethyl a5-dibromoadipat c, lifiuid fonn of (Le Sueur), T., 275 ;
P., 36.

CjoHivON 5-Ethylimino-l:l-dimethyl-A''-c2/cfohexen-3-ol, and its hydrochlor-
ide and platinichloride (Haas), T., 422.

C10H17ON3 Semicarbazone of l:l:5-trimethyl-A'*-c2/c/&hexen-3-one (Cross-
ley and Gilling), T., 24.

10 IV

CjoH^OoNoNas Substance, from tetraketopiperazine and sodium phenoxide (de
MoL-fLPiKU and Rule), T., 551 ; P., 7L

2262

FOHMILA INDEX. 10 IV II III

CioHfiO.NCli Trichlorobcnzoyllactoiiitrile (FnANcis and Davis'), T.,

1407.
CioHinN.BrjSi Substance, from silicon tetialiroiiiidc and pyridine (Reynolds)

T.,>)13.
CinHuOI.Hgo Dimorcuricaniplior diiodidc (.M.\i:s)i an<l SriiiiriiEits), T.,

ITb'.i.
CioHi^OClHg" Mercuricamplior cliloride (Maiisii and Stkitheiis), T., 1785.
CioHir.OBrHg' Mereuricauiplior bromide (Mau.sii and STRUTHER.f), T.,

1784.

CioHisOIHg MtTcuricainphor iodide, and its niprciiri-iolide (Maush anil
Stkuthers), T. , 1784.

10 V

CioH.jiOJsSHg Substance, fiom diethoxytbioxan, ethyl ioilidc and mercuric
iodide (Clarke and Smile.s), T., 1003.

Cii Group.

CnHinOo Ethyl ])henyIpropio!ate, action of, on monoarylcarbamides

(Ki-iiEMANN), T., 1609; P., 220.
A^ Dihydro-2-napIi thoic acid, resolution of, and the rf-acid and it.s sodium

salt (PiCKARDand Yates), T., 1014 ; P., 152.
C11H10O4 Methoxymethylenedioxy-o-hydrindone (Salway), T., 1210.
CiiHinOfl 3-Methoxy-4:5-methylenedioxycinnamic acid, and action of

nitric acid on (Salway), T., 1209.
C|iH,.jO l:l-Dimethyl-3-methylenephtlialan (Siiibata), T., 1453; P., 209.
CijHi.O.. Phenvlallylacetic acid, resolution of, and the d-acid and. its salts

(PicKAKD and Yates), T., 1016 ; P., 152.
C11H10O3 a-Benzoylbutyric acid (Hope and Perkin), T., 2047.
Ethyl benzoylacetate (Hope and Pekkin), T., 2042; P., 296.
C11H10O3 )3-3-Methoxy-4:5-niethy lenedioxypropionic acid (Salway), T.,

1209.
Ethyl 3:4-methylenedioxymandelate (Barger and Ewixs), T., 554.
CuHiiN.j l-Cyano-2-methyItetrahydrowoquinoline (Pyman), T., 1750.
CiiH]40.. Phenylpropylacetic acid, resolution of, and the f/-acid and its salts

(Pickard and Yates), T., 1017 ; P., 152.
)3-Phenyl-a-ethylpropionic acid, resolution of, and the rf-acid and its salts

(Pickard and Yates), T., 1018 ; P., 152.
CnHi403 Phenylpropoxyacetic acid, affinity constant of (Findlay', TrRNEi:,

and Owex), T., 940 ; P., 146.

CnHi406 Methyl l:l-dimethylcyc/ypentan-3:4-dione-2:5-dicarboxylate,

preparation of (Thorpe), P., 94.
CiiHieO.i Oxymethylenecamphor, condensation with primary and secondary

amino-compounds (Pope and Read), T., 171 ; P., 18.
CiiHisO l:l-Dimethyl-5-propvl-A''-C2/fWiexen-3.one (Crcsslev and Gillim;),

T., 29.

11 III

CuHgO-.N Lactone of o-cyano-v-hydrox y-7-phcn vlbutyric acid (Ha-

worth), T., 483.
CnHr,04N 2-Keto-8(5)-methoxy-6:7-methyleuedioxy-l:2-di h yd roquinol-

ine (+iH.iO), and its hydrochloride, and reduction products (Salway),

T., 1216r
CnHgOjCI; Ethyl 3 :4-d i c b 1 o r o ni e t li y I e n e d i o x y p li e n y 1 c h 1 0 r o a c e t a 1 0

(Barger and Ewins), T., 5,oS.

2263

11III-12II FORMULA INDEX.

CjiHqOsCI Ethyl 3:4-carbonyldioxyphenylchloroacetate (Barger and

Ewixs), T., 558.
CiiHqO-N 2(6)-N i t ro-3-m e t h o x y-4:5-raetliylcnedioxyciuuamlc acid

(Salway), T., 1215.
CiiHioOoNo /3-Iniino-a-cyano-7-pheiiylbutyric acid, and its silver salt

(BEsx'and Thorpe), T., 12.
l:3-Naphthylenediamine-2-carboxylic acid (Best and Thoute), T., 12.
CiiHioOjN Substance, (CnHioO^N),, from reduction of 2-keto-8(5)-niethoxy-

6:7-methylenedioxy-l:2-dihydro(iuinoline (Salway), T., 1217.
CnHnON., Triazoantipyrine {i.-tria-M-l-phenyl-2:Z-dimcthylpyrazolom)

(FoRsTEii and JIDllek), T., 2072 ; P., 291.
CiHiiOgN Carbethoxymandelouitrile (Francis and Davis), T., 1409.
CnHii04N Oxirae of methoxymethylenedioxy-o-hydriudone (Salway),

T., 1210.
CiiHnOsN e-Nitro-oiS-dimethoxy 1-hydrindone (Perkin, Rouinson, and

Thoma.s), T., 1980.
CiiHisOoN 6:7-Dimethoxy-3:4-diIiydro2,sy>(|uinolinc, and its hydrochloride

and'picrate (Pyman), T., 1618 ; P., 217.
CuHisOaN Ethyl phenylacetylcarbaniic acid (Ri:hemann and Priestley),

t., 452.
2-Amino-5:6-dinaethoxy-l-hydrindone, hydrochloride and jilatinichloride

(Robiksos), T., 2173 ; P., 296.
C11H13O4N 3:4-M e t hylenedioxy phenyl hydroxy ace timinoethyl ether,

hydrochloride of (Barger and Ewins), T., 554.
diHisON n-Butyro-o-toluidide (Davis), T., 1398.
?i-Butyro-/>-toluidide (Davis), T., 1398.
Cyanocarone (Clarke and Lapworth), P., 307.
CjiHisOsN Ethyl 5-cyano-2:5-dimethylc2/c^opentan-l-one-2-car boxy late

(JBest and Thorpe), P., 705 ; P., 93.
Ethyl 5-cy a n o-5-e t h y IcycZop e n t a n-l-onc-2-carboxylate (Best and

Thorpe), T., 707 ; P., 93.
Ethyl 3-cy an o-2-ethoxy-A--c?/c^opentene-l-carboxylate (Best and

Thorpe), T., 707; P., 93.
CiiHigONs Se'micarbazone of l:l-diinethyl-5-ethyl-A*-q/c/ohexen-3-one

(Crossley and Gillixg), T., 28.

C12 Group.

CioHioOo Benzylfurfuraldehyde (Fenton and RoniNsox), T., 1335 ; P., 193.
C,2Hio04 Quinhydrone, absorption spectra of (Hartley and Leonard), T., 34.
C10H10O5 Acetyl-;3-methyl8esculetin (Power and Moore), T., 256 ; P., 27.
C12H10O2 /3-Styryl-)3-methylacrylic acid (Haworth), T., 485.
Ci^HjsNs Phenylhydrazone of 2-cyanoc2/c^pentan-l-one (Best and

" Thorpe), T., 710.
C12H14O2 Diethylphthalide, fonnation from magnesium alkyl halides and

dim'ethyl or diethyl phthalate (Shibata), T., 1455.
C12H16O5 rf-Amyl gallate (McKexzie and Mijllek), T., 548. •

isoAmyl gallate (McKenzie and MtJLLEK), T., 547.
CjoHigOs Ethyl l:l-dimethyl-A'*-c2/c^ohexen-3-one-5-acetale (Ckossley and

GiLLINO), t., 23.
C]2Hj805 Ethj-1 c2/cZohexanone-3:6-dicarboxylate (Dobson, Ferns, and

Perkin), T., 2013; P., 263.
C,2H2o03 Ethyl pinonate (Perkin and Simonsen), T., 1174.
CjoHoriOi Etiiyl ct's-norpinate (Perkin and Simonsen), T., 1176.

2264

FORMT'LA INI^EX. 12 II- 12 III

Ci..H..i,0,i Ltu vulosediacetone, constitutiun of (Ikvink and Hynd), T., 1220;

P., 176.
Ci-.H.>.N.) 3:r)-Dicthyliinin(>-l:l-iHiiietliylc//f/ohcx;iii f, and its platinichloride

(llAAs), T., 422.

12 III

C).jHnON;) ^-Aminobenzenoazoplienol, and its liydroclilnridcs and tlieir

absorption spectra (Hkwitt and Tuumas), T., 1294 ; P., 190.
CioH]iO..>N Anliydridc of a-benzoylamino-i8-dinietliylacryl ic acid {Vv.n-

KIN and SiMONsEN"), P., 164.
Benzylfurfuialdehydeoxime (s-//;i and tinti) (Vksuis and Robinson), T.,

1336; P., 19.3.
Ci..HiiO;jN Ethyl phenylpiopioly 1 car b a ni i (• acid (Ruhemasn and

I'KiESTLKY), T., 451 ; P., 62.
CioHjiO^N 2-Keto-8(5)-methoxy-6:7-raethylened ii)xy-l-me t hyl-l:2-di hy-

droquinoline (Salway), T., 1218.
8(5)-Methoxy-6:7-methylenedioxycarbostyril methyl ether (Salwav),

T., 1218.
C1..H11O7N Methyl 2(6)-nitro-3-methoxy-4:5-methy lenedioxycinnama te

^Sai.wav), T., 1215.
Ci..Hi..ONj Styrylpyrazolecarboxylic acid livdrazide (Ruiikmann), T.,

117.
Ci..H,.>O..N., Methyl jS-ini ino-a-eyano-7-p!ien vlbii tyrate (BEsTand Thoki-e),

f.,"io".

Methyl l:3-naphthylenediaraine-2-carboxylate, and its liydrochloride

(Best and Tiioupe), T., 11.
Ci.HiiON o-Benzoylamino-/3-diniethvlacrylic acid (Peiikin and Simun-

.><EN), P., 164.
Cj2H,:i0jN l-Phenylpyrrolidine-2:5-dicarboxylic acid, formation of, from

adipic acid, and its barium, and silver salts (Le Sueur), T., 273 ; P., 36.
Oxy/socotaruine (2: fCeto-S(5)- metJwxi/-6:7 -7nethyle7ieilioxy-l-')ncthyl-l:2:3-A-tel ni ■

hydroquinoline) (Hxlway), T., 1219; P., 175.
CoHiiOsN Methyl 2(6)-amino-3-methoxy-4:5-methylenedioxy('innama te

(Salway), T., 1215.
CioH]jNtSi Substance, from silicochloroforni and potassium pyrrole (Reynolus),

T.,'511.
CoHijOsNo Ethyl 2-ke to-4-carbethoxy<lihydrowopy r r 0 1 y 1-5-c y a n o-

acetate (Be.st and Thorpe), T., 1520.
Ethyl 2-keto-4-carbethoxytetrahydropyrrolidene-5-eyanoac etate,

and its silver salt (Best and Tuori-e), T., 1521.
CioH]-,ON Anilide of )3-methyl-/8-ethylacrylic acid (Gardner and

Hawortii), T., 1962.
CioHi^OsN l-Keto-6:7-dimethoxy-2-me t hy 1 tetrah y d r ozsoquino 1 ine

(Pyman), T., 1272; P., 190.
Ci2Hi-,04N Cotarnine, synthesis of substances allied to (Salway), T., 1204 ;

P., 175.
CjoHisOjNs Ethyl 2-imino-4-carbethoxytetrahydropyrrolidene-5-cyano-

acetate, and its hydrochloride (Best and Thorpe), T., 1519.
Cj.iHiANo Ethyl o5-dicyanoadipate (Best and Thorpe), T., 696 ; P., 92.
CioHnON 3-Cyano-l:2:4-trimethyl-4-ethyl-Ai-^cycMiexadien-6-ol (Garu.ner

and Haworth), T., 1960.
C10H17O0N 6:7-Dimethoxy-2-methyltetrahydro/4-oquinoline, and its salts

(Pyman), T., 1273; P., 190.
CjoHi-OoN 4:5-Dimethoxy-2-i8-methylaminoethylbenzaldelivde (Pyman),

T.,''l270 ; P., 190.

2 -265

12 III 13 II FORMITLA INDEX.

C|.H|70:iN G:r-Diiue thoxy-'i-niet hyl-3:4-i.liliydrot,s'oi|uinoliiiiuiii li y d r-

oxide, chloride, bromide, aurichloride, and picrate (Pyman), T. , 1271 ; P.,

190.
Ci.2H]sO;(N4 Seniicarliazone or ctliyl r)-cyaiio-2:5-diinet liylr/zr^pentaii-

l-o'ne-2-carboxylate (Best and Thoiu'e), T., 705.
Cj.jHoiONs Semicarbazone of l:l-diinetliyl-5-proi)y l-A^-c'?/c7ohcxen-3-one

('Cros.slfa- and GiLLiNG), T., 29.
CioH.«0.,S2 isoAmyl dithio-oxalate (Jones and Taskei:), T., 1906 ; P., 247.
Ci-jH^OjSo Diethyl o-dithiodibutyrate (Pnu'E and Twis.s), T., 1052 ; P., 165.
Diethyl a-dithiodi/wbutyrate, preparation of (PniCE and Twis.s), T., 1054;

P., 165.
Ci..H.>c04S Acetal sulphide, molecular refraction of, and niercurichloride

("Ci.AiucE and Smiles), T., 1000 ; P., 145.
Ci,H,>70aSb /,wT?utyl antimonite (MacKey), T., 607 ; P., 98.

12 IV

Ci..H.',0,,N.-,S T e t r a n i t r o d i p h e n y 1 a ni i n e-o-s u 1 p h o x i d e, and its sodium deriva-

tives'(liARNETT and Smiles), T., 1257 ; P., 195.
Tetranitrophenazothionium hydroxide, reactions and sodium derivative

of (Bahxett and Smiles), T., 1259 ; P., 195.
C12H5O10N5S Sul phone, from oxidation of tetranitro])lienazotliionium hydroxide

(Bakxett and Smiles), T., 1261.
CjoHvOsNjS 3:9-Dinitrophenazoth ionium hydroxide (Bahnett and

Smiles), T., 1261.
woDinitrophenazothionium hydroxide (and + 11,0) (Barnett and

Smiles), T., 1264; P., 195.
CioH70,3N:!S Substance (+ HgO), from oxidation of dinitroazothionium hydroxide

(Barnett and Smiles), T., 1264.
Ci-.HsOjNoS 3-Nitro-9-hydroxyphenazotliionium hydroxide (Barnett

and S'miles), T., 1262.
Ci2HsNClS Phenazothioninm chloride (+ H.^O) (Barnett and Smiles), T.,

1265; P., 195.
C]2HgONS Diphenylamine o-sulphoxide (Barnett and Smiles), T., 1265;

P., 195.
Ci2Hi2N5ClS Diaminothionine oliloride (+ 2H2O), and platinichloride

(Barnett and Smiles), T., 1259.

12 V

CiaHgOoNIsS 2:4:5-Tri-iodobenzenesulphonanilide (Boyle), T., 1716.
3:4:5-Tri-iodobenzenesulphonanilide (Boyle), T., 1713.

Ci3 Group.

CisHioOg Tannic acid, iodometric estimation of, and action of reducing agents on

(Gardner and Hodgson), T., 1819.
C13H12O2 Tolylmethylfurfuraldehyde (Fenton and Robinson), T., 1338.
C13H14N2 Diphenylmethylenediamine, action of, on phenyl thiocarbimide

(Senier and Siiepheard), T., 498.
C13H16O3 Ethyl a-benzoyhsobutyrate (Hoi-E and Perkin), T., 2046.

rf-Amyl phenylglyoxylate (d-cmiyl benzoij/formate) (McKENZiEand MiJLLER),

T., 546.
CisHieOg Glycide thymyl ether (Boyd and Marle), T., 1800 ; P., 235.
C13H20O3 Ethyl l:l-dimethyl-A''-c?/cZohexe|n-3-one-5-propionate, hydrolysis

of (Crossley and Gillino), T., 28.

22GG

FOUMT'LA IXDEX. 13 H 13 jy

Ci|H..,iO,j Ktliyl a7-ili,icctylf,'lutaratu (SiMn.ssiiN ami Stouky), T., 'Jill:

P., -290.
Ci:,H^04 Ethyl cyc/ohexyliualoiiate (Hoi'E aiul Pekkin), T., 1363 ; P., 207.
C13H20O5 Ethyl r/.fliydroxypinate (Pekkin and Simonsen), T., 117t).
Ci,H».0|i ^letliyl a-hfvulosediacetone (IiiviNE and Hynd), T., 1223;

P., 170.

13 III

C,:;HiiOoN o-Cyono-)8-styryl-)3-methyhicrylic acid (IIawortii), T., 4Sr..

Salicylideiie-?/i-aininophenol (Skxieu and Siiei'IIF.aiu)), T., 1947.
CitHi-ONi Benzoyl-;;-plienvleiiediannnc, hy.lrocliloride of (Mhiican and

Alcock), T., 1323 ; P., 202.
C)iHi..O..N., 2-Cyano-5-carbanilinon/'/fi)cntaii-l-one (Best and Tiioi;i'k),

T., 701.

Ci:;H).jO;;N4 0-, m-, and jo-Nitrobcnzened iazohydro.\ylaniino-/)-tohu'ne

(GEiniAitD and Thompson), T., 774.
C|;iHkiOoN Ethyl a-cyano-a-styrylacetate (Hawout}!), T.,482.
CiiHiiOiN o-Car boxy a mi no-/8-stvrvl-;8-m ethyl acrylic acid (IIawohtii),

'i., 485. ' '

Ci:iHi;,04P Phenyl-;;-tolylphosphoric acid (Luff and Kipi-ing), T., 2001.
Ci;Hi;07N E t li y 1 2(6)-u i t r o-3-methoxy-4:5-methy lenedioxycinnamate

(Salnvav), T., 1215.
Ci iHjiiOoN., 1-Cy a n o-6:7-d i ni e t h 0 x y-2-niethyl telrahydro/.soti ii i n o 1 ine

(Pyiian), T., 1272; P., 190.
Ci:,Hie0gN2 Ethyl 2-keto-4-carbethoxy-l-methy Itetrahydropynolidene-
S-cyanoacetate (Be.st and Thorpe), T., 1529.
CiiHifiOgNj 2:5-Dinitro-4-acetylamino-3-piperidylp]ienol (ilRLixiLA and

Hay), T., 1049.
Ci;Hi70iN 1-K e 1 0-6: 7-d i me t li 0 xy-2-e t h v 1 1 e t r a li v d r o/.wi] u i n o 1 i n e (Pyma n),

T., 1746.
Cj ;Hi707N Glucose-o-carboxyanilide (+ H.,0), and its sodium salt (Irvine

and GiLMouK), T., 1553; P., 219.
Ci:iHis02N.3 6-1 niino-3-cyano-l:2:4-trimethyl-4-e thy l-A'-c/yc/yh oxen e-3-carb-

oxylic acid (Gardner and IIawortii), T., 1959.
Ci,Hiq0.iN 6:7-Dimethoxy-2-ethyItetrahvdiofsoquinoline, and its hydro-
chloride (Pyman), T., 1746.
Ci;iHir,OoN-> Phenylhydrazone of 2:3-diketo-4-phen vl-5-aii isylp3-iroline

(Ruhemann), t., 1608.
Ci-.HigOsN 4:5-Di'methoxv-2-/3-ethylaminoeth vlbenzaldehyde (Pyman),

T., 1745.
6:7-Dimethoxy-2-ethyl-3:4-dihj'droi5oquinolinium hydroxide, chloride,

anrichloride, and picrate of (Pyman), T., 1745.
Ci;fHi905N Glucose-;7-toluidide (and + ilLO and -i- H^O), crj'stalline forms of,

and reactions of (Irvine and Gilmour), T., 1546 ; P., 219.
CijH-^iOaNs * Semicarbazone of ethyl l:l-dimethyl-A'*-c?/c/ohexen-3-one-5-

acetate (-1- iEtOH) (Ckossley and Gilling), T., 24.
CKiHoiO^BP Ethyl o-bromoe?/cZohexylmalonate (Hope and Perkin), T., 1364.
C13H23ON Propionobornylamide (Frankland and Barrow), T., 2025;

P., 263.

13 IV

Ck;HioONC1 Salicylidene(-o-, -m-, and -2;-)chloroan iline (.Senier and

Shepheard), T., 1946.
C1H10ON3CI Benzoyl-js-aminobenzenediazonium chloride (Morgan and

Alcock\ T., 1-323; P., 202.

2-2G7

13 IV 14 111 FORMULA INDEX.

C,iH i,iOjN,iS-. M e t h a 11 e d i s u 1 p h o 11 y 1 b i s-/'-}) li e ii v 1 e ii e d i a z o i in i d e (Morgan

and PiCKAKD), P., 301.
CiiHu)0',N-Cl Hcnzoyl-ju-aiuiiiobeiizenediazoniuiii pcrchlorate (Mokgan

and Au-ocK), T., 1324 ; P., 202.
Ci-HiiOoNoP P li e n V lim i n 0 p h 0 s p li o r V 1 b e 11 z ain i d e (Titherley and

AVouuall), T., 1152 ; P., 150.
CisHnOoNjS Toluene-oj-sulphoii vl-;)-pheuylenediazoimide (Morgan and

PlOKAllD), P., 301.
Ci:iHi.jON:tBl' 0-, VI-, and j()-Bromobenzenediazohydroxylamino-^-toluene

(Gebiiaui) and Thompson), T., 775.
Ci^HioOiClP Phenyl-^)-tolYlpliospliorvl cliloride (Luff and Kipping),

f . , '2000.
Ci3HuOoN.>S Tol ue ne-co-s ul p li 0 n y l-^j-phcnylenediamine (Morgan and

Picka'kd), p., 301.
CjjHirjO.iN.iP A nilino-jo-toln id in 0 phosphoric acid, and its alkaloidal salts

(LrFp'and Kipping), T., 1998.
CiiHi„04N4So Methanedisulphon vlbis-/)-phenylendianiine (Morgan and

PiCKARD), P., 301.

13 V

Ci3HioOoN.,ClP Benzoylaminoanilinophosphoryl chloride (Titherley
and'WoRKALL), T., ll.f;2; P., 150.

Ci4 Group.

C]4HioOo Ben zil, physical properties of solid solutions of, and benzoin (Vanstone),
T.,"600 ; P., 30.

Ci4Hi.)02 Benzoin, physical properties of solid solutions of, and beiizil (Vanstone),
f., 600; P., 30.
rf-Benzoin (Wren), T., 1583; P., 219.

C14H14S0 Benzyl disulphide, prejiaration of (Price and Twiss), T., 1490;
P., "211.

CuHuSe.j Benzyl diselenide (Price and Jones), T., 1729 ; P., 234.

C14H18O3 Ethyl a-benzoyl-o-niethylbutyrate (Hope and Perkin), T., 2050.

C14H.24O3 Ethyl a-l:l-diniethyl-A'*-c?/(;Zohexeu-3-one-5-butyrate, and hydro-
lysis of (Crossley and Gilling), T., 28.

C14H24O4 Ethyl l-methylc)/c/ohexy]-4-malonate (Hope and Perkin),
T., 1367.

C14H24OS Ethyl o-niotlioxycT/r/ohexylmalonate (Hope and Perkin), T.,
1366.

C14H04O6 Ethyl pentane-aSe-tricarboxylate, preparation of (Dobson, Ferns,
and Perkin), T., 2012.

14 III

CuHciOgNs Trinitrohydroxy-1-o-, -m-, and -^j-hydroxyphenylniethylbenz-

iminazole (Meldola and Hay), T., 1045.
C14H10ON4 Benzoyl-;j-aniiuodiazobenzene cyanide (Morgan and Ai.cock),

T., 1324.
CuHioO.^N l-Benzoyloxy-5-phenyltetrazole (Foilster), T., 188 ; P., 25.
C,4Hio0.jS2 Phenyl dithio-oxalate (Jones and Tasker), T., 1905 ; P., 247.
Ci4H]o04S2 Substance, from action of sulphur moiiochloride on sodium benzoate

(Denham), T., 1237.
C;4Hio06N4 Dinitrohydroxy-l-o-, -m-, and -^-hydroxyphcnylmethylbenz-

irainazole (Meldola and Hay), T., 1044.

2268

FORMl'LA INDEX. 14 HI

C,,H|,ON 2-(or 4-)Mctliylacridoiie (Skmek ami Shepiieaup), T., 444.

I'hr II V Ibenzometoxazoiie, action of pliosiilioius pentacliloride on (Titiiehi.ey

aii<l Hicks), T., 915 ; P., 95.
CuHnO.iN Salicylidene-/)-aminobenzoic acid, and its salts (Senieii and

SiiKi'HEAUD), T., 1948.
CijHioON., Methylenediphenylcarbamidc (SENiERand Siiei'IIEAHD), T., 504.
C,4H,.jO:,N.> 4-Nitioso-4'-acetylaniinodiiilienyl (Cai.v), T., 717; P., 123.
Ci^HioOiNo (3- and 5-) XitrosalipvHdene-?/i-tolu idine (Seniku and Siiep-

heakd) T., 1953.

CnH|..04No oa'-Uicyano-/3-bi'nzvlf,'lutaric acid, and its silver salt (II awokth),
T., 4 84.

Ci.,Hi;(ON Salicylidene-//(-toluidine, a new phototropic compound (Seniek
and Shepheakij), T., 443, 1945 ; P., 61.
;/(- and ^-Hydroxybenzylideue-w-toluidine (Senier and Siiepiieakd)i
T., 1951.

Ci4H,:j0.jN /-Benzoin-o-oxime, and its inutarotation (When), T., 1587.
Salicyl-/«-toluidide (Se.\ieii and Shepiieaud), T., 444.

CuHjiOoNs p-Acetylaniinobenzeneazophenol (Hewitt and Thomas), T.,
l';94 ; P., 190.

CiiHuON., «s-Benzoylmethyl-»-plienvlenediamine (Morgan and Alcock),
T., 1322; P., 202.

Acetylbenzidine, preparation of (Cain), T., 716; P., 123.
CijHuOS Benzyl sulphoxide; a possible example of dynamic isomerism
(S.mytiie), T., 349.

CiiH,40..N.2 2-Cyano-5-carbanilino-2-metliylc(/cAvpen tan-1-one (Best and
Thorpe), T., 703.

Ci4Hi50N:j Diniethylamin 0 beuzeneazophenol, and its absorption spectra,
and h3-drochloride (Hewitt and Thomas), T., 1295 ; P., 190.

0-, m-, and /j-Tolvldiazohydr oxvlamino-;;-toluene (Gebiiard and Thomp-
son), T., 772.

Ci4HibO;,N2 Ethyl 2:6-dicyano-l:l:5-trimethyl-A---'-C(/c/ohexadien-3-ol-6-

carboxylate (Garuxer and Haworth), T., 1958.
Ci4H]704N Methyl l-phenylpvrrolidine-2:5-dicarboxylatc (Le Sueur),

T., 277; P., 36.
C,4Hi706N /-Mandelonitrile glucoside, isolation of, from Prinnis scrolina

(Power and Moore), T., 243 ; P., 27.
Indican (+ 3H.,0), experiments on, and estimation of (Perkin and Thomas),

T., 793; P., 12"5.
Cj4HisONo Cinnamenylpiperidylcarbamide (Forster), T., 439.
CuHigOyN l-Keto-6:7-dimethoxy-2-propyl t etrahydro/s'Xiuino li ne (Pv-

max), T., 1748.

Ci4Ho,0.)N 6:7-Dimetlioxy-2-propyl tetrahydroi4'"i]uinoline, and its hydro-
chloride (Pyman), T., 1748.

CijH.nO-jN 4:5-Dimethoxy-2-/3-propvlamiiioethylbenzalde}iyde (Pyman),
t., 1747.
6:7-Dimethoxy-2-propyl-3:4-dihydro/AO([uinolininm hydrox id e, chlor-
ide and picrate of (Pymax), T., 1747.

Ci4HoiOeN Glucose-j9-phenetidide ( -(- .UI.2O and -t-H.,0), properties of (Irvine
and Gilmour), T., 1550 ; P., 219.

Ci4H.>jOsN4 Tetraethyl ammonium styphnate, preparation and crystal -
logi-aphy of (Jerusalem), T., 1287.

C14H.J3O4BP Ethyl a-bromo-l-methylcyc^hexyl-4-malonate (Hope and
Perkin), T., 1367.

Ci4H.,50N /i-Butyrobornylamide (Fraxki.anu and Barkow), T., 2025; P.,
263.

xcv. 22(;!) 7 K

U III- 15 III FORMULA INDEX.

Ci4Ha;04So Diethyl a-di thiodi/sovalerate (PiiicE and Twiss), T., 1055;
P., 165.

14 IV

Ci4Hg03N2S Ethyl 3-cyano-4-keto-2-phenvlimiiiotetrahydiothiophen-

3-carboxylate (Ruheman'n), T., I2l.
C14H9O6N4BP Dinitrohydroxy-l-o-, -m-, and -jw-biomophenylniethylbenz-

irainazole (Meldola and Hay), T., 1040.
C14H10OSN4S Dinitrohydroxy-l -^-s ulphophenylmethylbenziminazole

(Meldola and Hay), T., 1047.
C14H10O9N4S Dinitrohydrox y-1 -o-h ydroxyphenylmethylbenziminazole-

sulphonic acid (SIeldola and Hay), T., 1044.
C14H11O3NS Benzenesulphonylmandelonitrile (Francis and Davis), T.,

1408.
C14H12ONCI o-Methoxybenzylid ene-t>-chloroaniline (Skniek and Shei'-

HEARD), T., 1947.

C14H12ONBP 5-Bromosalicvlidene-M-toluidine (Senier and Shepheard),

T., 1953.
C14H10O3N4S ^-Toluenesulphonyl derivative of l-hydroxy-5-phenyltetr-

azole (FoRSTER), T., 189 ; P., 25.
C14H12O4N0S2 o-Nitrobenzyl disulphide, preparation of (PaiCE and Twis.s),

T., 1490; P., 211.
Ci4Hi204N2Se Nitrobenzyl diselenide (<?-, m-, and p-) (Price and Jones),

T., 1729; P., 234.
C14H14ON3BP Bromo-o-, -m-, and -jo-tolyldiazohydroxylaraino-js-toluene

(Gerhard and Thompson), T., 1119.
Ci4H);0yN3M02 B e u z o y 1 ni e t h y 1-jo-a m i n o b e n z e n e d i a z 0 n i u m ni o 1 y b d a t e

(Morgan and Alcock), T., 1325 ; P., 202.

14 V

C14H9ONCI7P Substance, from phosphorus pentachloride and phenylbenzo-

metoxazone, and benzoylsalicylonitrile (Titherley and HiCK.s), T., 918.
C14H10O2NCI4P Substance, from phosphorus pentachloride and phenylbenzo-

metoxazone (Titherley and Hicks), T., 919.
C)4Hci02NCl5P Substance, from phosphorus pentachloride and phenylbenzo-

metoxazone, and benzoylsalicylonitrile (Titherley and Hicks), T., 918.
Ci4H3i04l3SHg Diacetalet hylsulphonium mercu ri-iodide (Clarke and

Smiles), T., 1001.

Ci5 Group,

CijHsOti Rhein, preparation of (Robinson and Simonsen), T., 1092.
C)oHio04 Chrysophanic acid, constitution of (TuTiN and Clewer), P., 200.
C15H10O5 Emodin, con.stitution of (Tutin and Clewer), P., 200.
C15H10O7 Quercetin, from Thcspas^ia lampas (Perkin), T., 1859 ; P., 248.
CjsHioO, Gossypetin, irom Hibiscus sahdariffa {'Pekki-s),T., 1855; P., 248.
C15H14O2 /-Benzoin methyl ether (Wren), T., 1584.
CirHuOv Carthamine (Kametaka and Perkin), P., 223.

C15H20O3 Ethyl a-beuzoyl-a-ethylbutyrate, preparation of (Hope and
Perkin), T., 2048.

CijHaoOs Androsin (+ 2H2O) {acetovanillonc glucoside) {Mo(tnE),T., 746; P., 85.
CisH^^Oj Ethyl a-rnethoxy-l-methylc2/c/ohexyl-4-malonate (Hope and
Perkin), T., 1368.

15 III

C);Hio03N2 2>-Nitrobenzaldehydeindogenide, quantitative experiments with
(Perkin and Thomas), T., 796 ; P., 125.

2270

FORMULA INDEX. 15 m

Cir.HinOjNj //(-NitrobiMizoylinanclelonitrilu (Fkan'CIs and Davis), T., 1408.
C|r,Hii,07N4 Dinitrohy (lioxy-1-o-, -?«-, and -p-carboxypliciiylnii't liy Ibtiiz-

iiniiiazole, and their silver .salts (Mei.doi.a and H.VY), T., 1041.
Ci:,HnON 2:5-Diphenyloxazolc, synthesis of (RoniNsoN), T., '^109 ; P., 29.').
Cir.HiiOoN Benzoylmandelonitrile (Fil-vxcis and Davis), T., 1404.
^-Hydroxy benzaldelivdeindogenide (PKiticiN and Tikjmas), T., 799;

1'., 12-..
Cr,HiiO;N Dihydroxvbenzaldehydeind()<,'enide (Tkukin and Thomas),

T., 798; P., 12r..

Ci,r,Hi.>OBP.> o)3-Dibr()iuol>enz3'lacetoi>lienone, stereoisomerie niodilicatiuns of
(Smkulfa-), p., 259.

C,,H|.ON //(-Benzoylaiuiiiostyrene (+ 1I.,0), preparation of (Tuns, Caton',
;iiiii Hann), T., 212;"..

C|;,H,:iOoN Piperonylidene-..(-toluidine (Skniek and Siiei-iieari)), T., 1951.

u.-i)iii/.(.y laniinoacetophenone (Robinson), T., 2169; P., 295.
Ci;,Hi;;0:;N 0-M c t li o X y 1. e 11 z y 1 1 d c H c-jij-a 111 1 u o b c D z o i c acid (Senieii and
SllEl'IIEAIiD), T., 1949.

Ci-,H,iO{Ni Beiizoyl-7)-aminobenzenediazoniuin acetate (Moikjan and
Alcock), T., 1323 ; P., 202.

Ci.HijO^N 5-B e 11 z o y 1 amino-l-metlu)xy-2:3-inct]i vleneiliox3'benzene
(Salway), T., 1162.

Ci.-.HuONj Cinnameuylphenylcarbamide (Forsteu), T., 439.
Ci.HuCN Benzoyl-y-liydroxyphenylethylaniine (Bakgek and Waijoi.eI,
T., 1722; P., 229.

CioHuOiNo Beuzoyl-/;-uitrophenylethylaniine (Bakcek and Wai.pui.e),
T., 1721 ; P., 229.

Cir.HuNjS 3-PheDyI-6-methyl-2-thio-l:2:3:4-tetraliydro(|uinazoIinc, and
its platiniclilorides (Senieu and Shepheaiil.), T., 499.

Ci:,Hi,-,ON 2-Hydrox3'-5-nietliylbeiizvlidene-;«-t o 1 u i d i 11 0 (Senieu and
Siiei'IIEARD), T., 1952.

Anisylidene-;/i-toluidine, and its hydrocidoride (Senieu and Shei'IIEARD),

T., 1952.
Salicylidene-o-4-xylidine (Senier and Shei'IIEAUk), T., 1945.
Salicylidene-?tt-4-xylidine (Sexier and Siiepheaud), T., 443.
Salicylidene-2?-xylidine (Seniei: and Shei'Heard), T., 443.
CisHioON;., Cinnamenylphenylsemicarbazide (Forster), T., 439.

CjsHir.OoN o-;?-Hydroxy-iV"-benzoylpheuylethylaTnine (Tuns', Caton, and
Haxn),T., 2123.

)3-^-Hydroxy-jV-bcnzoylplienylethylamine (Barger), T., 1128.

Vanillidene-m-toluidine (Senier and Siiepheaud), T., 1954.

Salicyl-?/i- and -^-4-xylidide (Sexier and Shepiieark), T., 444.

CisHieONo Benzoyl-^-aminophenyletliylamine, and its hydrocidoride
(Barger and Walvole), T., 1722 ; P., 229.

fw-Benzoylethyl-jij-plienylcnediamine (Morgan and Ai.cock), T., 1322;

P., 202.
C^jHi-ONj ;;-Metlioxybcnzeneazodimethyianilin e, and ab.sorption spectra

of (Hewitt and Thomas), T., 1298 ; P., 190.
Ci.^Hii.OoN Benzoyltropeine, and its salts (Jo-wett and Pvman), T., 1028.
Ci=,Hi<,OjN 0-, m-, and ;;-Hydroxybenzoyltroi>eine, and their salts (Jowett

and Pymam), T., 1031.
CinHonOjN., Phenylcarbamotropeine, salts of (Jowett and Pyman), T., 1027.
C15H01O5N Myristicinvlideneaminoacetal, and its reduction products

(Salway), T., 1211. ""

2271

,5 III 16 III FOiniT-LA INDFA'.

C, Hv.O-N.. ri-Iniiiio-'2-t!yano-l:3-iliinotliyl-G-otliyl-3-piopyl-A''-f?/c-/oliexene-

i'-i';u lioxylie acid (Gaudnku and Haworth), T., 1962.
Ci-,H.>tOr,N M vristicinylaminoacetal and its li3'drochloride (Salway),

f.,"l'2rJ.
Ci5H330:!Sb Aniyl antimonite (MacKf.v), T., 607 ; P., 98.
i'soAmyl antimonite (MacKky). T., 007; P., 98.

15 IV

C,-,Hi„OoNCI yi-C h 1 or ol) c n zoy 1 niaiidcloiiitrile (FiiAXCis and Davis),

T.."h06.
Ci-HjiON-S.. Anlij-drodiphenyldithioliiuretfarboxylic acid (Km em ANN

and PiuEsTLEY), T., 455 ; P., 62.
Ci-Hi-OijNiMOo Bcnzoylethyl-7)-aminobenzenediazoniuni molybdate

(.Morgan and Alcock), T., 1325 ; P., 202.
Cj-HisONsI I'-Dimethylaminobenzeneazoph enol methiodide (Hewitt

and Thomas), T., 1296 ; P., 190.

Cir, Group.

CbHioO,; Rhein methyl ester (Robinson and Simonsen), T., 1092; P., 76.
CisHijOo Dibenzoylethylene, refraction of (Smedley), T., 219 ; P., 17.
CigHioOs Benzoylbenzylideneacetic acid, and its sodium salt (Rciiemann),

T", 116.
CisHjoO^ 2:3:6:7-Dimethylenetetraoxydihydroantlnacenc (Ewix.s), T.,

1486; P., 211,
Cj.-Hi-.O., Hydroxydimethoxyanthraquinone (Robinson and Simonsen),

f.,1095.
CifiHioOe Chrysoeriol (Tutin and Clewer), T., 85 ; P., 12.
Ci,;HuO:>, 5/i-Toluic anhydride (Denham), T., 1240.

Acetyl-^-benzoin (Wren), T., 1585.
CiflHuOg Brazilin, derivatives of (Perkin and Robinson), T., 381 ; P., 31.
CifHi406 Hsematoxylin, derivatives of (Perkin and Robinson), T., 381 ;

P., 31.
CifiHjsN Cinnam}'lidene-//(-toluidine, nnd its liydrochloride (Senier and

Shepheard), T., 1955.
C16H1SO4 Pinacone, from y/-Iivdroxyaeetoplienone (Tutin, Caton, and Hann),

T., 2122.
CitjHigN Aminotetramethyldiphenyl (Crossley and Hampshire), P., 163.
Cir.HooN., D iphenyldimethylethylen ediamine, dihydrochloride of (Dunlop

Und" Jones), T., 418.
C16H24O6 Diethyl 6-acetyl-l:5-dimethyk//c/ohexan-3-o ne-2:6-dicarboxyl-

ate (Ruiiemann), T., 115.
CioHosOr, Ethyl o-ethoxycycZohexylmalonat e (Hoi-e and Perkin), T., 1366.
CieH28Si ]}enzylethylpro])3'liwbuty Isilioane (Kii'I-ing and Davis), T., 73;

P., 9.

16 III

CigH.^ON Phenyliminocamjihor (FuitsiER and Tikirnley), T., 949.
Cj.jH^OioN Nitrodiphenyltetracarl)oxylic arid (Ci;o.s.SLEY and Hamr-

SllIRE), p., 162.
CieHifjO.jN.^ Indirubin, reduction of (Perkin), P., 127.
C,gH,oO.,CL 5:8-Dichloro-l:2-, -1:3-, and -l:4-dimetliylanthraquinone

(HARi-roR, XoRRis, and Weizmann), T., 1314.
Cir,Hio07N4 2:5-Dinitroresorciuolazo-;3-napli thol (Mei.dola and Hay),

T., 1385.

2272

FOUMII.A IXnEX. 16 III

CieHiiOoN DikctocliiilMMiyli.yiruline (KriiKMANM, T., 989.

CiiiHiiOjN M ft li vleiiedioxy hfuzalililiyiifiiulo^'ciiidr (I'kkkin au<l

Thomas), T., 796 ; P., 125.
CuiHiiO.N., 4-Nitro-2-bciizt'iicazo-o-iiaiilitliol (MrniiKi.i, and Smith), T.,

1431 ;■ P., 209.
2-Nitio-4-I)cn2eneH20-a-naiilitliol (Mitchell and Smith), T., 1432; P., 209.
dijHiiOjN Beiizoyloxyliomoiiiperonyloiiitiile (FkaniIs and Davis),

T., 1406.
CirtH|..O..N.. Pli'juylpioitiolylplifnvlcarbaniidc (Uuhe.mann), T., 1609 ;

i\,'-220.
Oxime of diketodiplienylitynolinc (Ki iikman.n), T., 1605.
CirtHioO.Nj Tetraketo-2:5-dianilinopii)c;razine (de Mouii.riKD and Rri.E),

f.,?..')!.

C,„H,ACl. 3:6-Dic-hloio-2':3'-,-2':4'-, and-2':r/-dinicthyl-2-benzoyll.enzoic
acid (Hakkop, Norui.s, and Weiz.mann), T., 1314.

Ci,iH|..0,N.. 7n-Nitrobenzoyl-y;-metlioxyniandelonit rile (Fiiancis and

Davi.s), T., 1408.
Ci.iHi^ON 5-PIienyl-2-benzvloxazole, and picrate of (Robinson), T., 2170;

P., 295.
CirtH,:,OoN Bfiizoyl-yv-tolylglycollonitrile (Francis and Davis), T., 140."..

Dikctodiplienylpyriolidine (Ruhemann), T., 990.
CirtH,.;0;tN j:J-Anisoylmaudclonitrile (Fuancis and Davis), T., 1407.

Benzoyl-o- and -^j-methoxymandelonitrile (Francis and Davis), T., 1405.
C|,;H,i04N Aminodimethoxyanthraquiuone (Robinson and Si.monsen),

T., 1095.
CieHuO-N Substance, from anisaldehydecyanohydrin and liydrogen chloride

(McCombie and Paiiky), T., 587 ; P., 95.
CifiH|404S.2 Substance, from .sulpliur nionochloridc and silver plienylacetate
(Denham), T., 1239.
Substance, from sulpliur monocldoride and silver o-toluate (Denham), T., 1239.
Substance, from sulphur monochloride and silver m-toluate (Desham), T.,

1239.
Substance, from sulphur monochloride and silver ^7-toluate (Denham), T.,
1240.
CifiHjoOoN to-Phenylacetvlaminoacetophenone (Robinson), T., 2170; P.,

295:
C1HH15O4N 1:2-Dihydropapaverolinc, and its hydrochloride ( + iHoO) (Py-

MAN), T., 1622.
CiriHirtO.No oj-Pheuylacetylaminoacetophenoneoxime (Robin.son), T.,
2170;" P., 295.
4-Nitroso-4'-acetylamino-3:3'-ditolyl (Cain), T., 717; P., 123.
CigHifiNoS 3-0- and -;j-Tolyl-6-methyl-2-thio-l:2:3:4-tetrahydroquiuazoliue

(Senier and Shepheard), T., 503.
CiHHi6N4Si Silicotetrapyrrole (Reynolds), T., 505.

C10H17ON o-Methoxybenzylidene-o-4-xylidine (Senieu and Shepheard),
T., 1946.
Salicylidene-i^-cumidine (Senier and Shepheard), T., 443.
Ci,H.-OoN a-H y d r o X y-j3-p henylacetylamino-a-phenylethaue (Robinson),
t., 2171 ; P., 295.
Salicyl-i/z-cumidide (Senier and Shepheard), T., 444.
Nitrotetramethyldiphenyl (Crossley and Hampshire), P., 162.
CieHi-OoNs ^-Dimethylaminobenzeueazophenyl acetate (Hewitt and

Thomas), T., 1296 ; P., 190.
CieHnOgNg 0-, m-, and^-Carbe thoxybenzenediazohydroxylamino-j:>-tolu-
ene (Gebhard and Thomp.-50N), T., 773.

2273

16 III 16 IV FORMULA INDEX.

CiiiHivO^N Tot raliydropapaveroliue, hydrochloride of (Pymax), T., 1619.

C,«H,sON, Acctyltolidiiie ( + HoO) (Cain), T., 717 ; P., 123.

C,,Hi.,O..N //)- ami ;)-Hydrox3'pheiiylimiuocamphor (Forstek and TiioitN-

lky"), T., I\o0, 954.
CicHi..O-,N Glucose-)8-uaphthylamido ( + H.,0) (Irvine and Gii.mour), T.,

1.^5'2 ; P., 219.
CjrtH.HiOoN.. Nitrosophcnvlaniinocamplior (Forster and Tiiounley), T.,

9o0.'
Ci6H.Y.0-N4 Cami)horvl-o-, -?«-, and -^J-nit roplienyl triazen (For.ster and

Garland), T., 2062".
C,,iH..,ON Phenylamiuocamphor (Forster and Tiiornley), T., 950.
CisHoiON'! Phenylhydrazone of 2sonitrosocamphor, isomeric forms of

('Fokster and'THORNLEY), T., 956.
Oxime of camphor(|uiuonephen vlh vdrazone (Forster and Tiiorni-ev),

T., 955.
Camjihorylphenyltriazen, and its silver derivative (Forster and Gar-
land), T., 2051 ; P., 244.
C)6H2iOoN i'-Hydroxyphenylaminocaniphor (For.sTER and Thornley), T.,

95 L
Phenylacetyltropeine, salts of (Jowett and Pvman), T., 1028.
CihH.iOjN Ethyl l-phenvlpvrrolidine-2:5-dicarboxvlate (Le Sueur), T.,

276 ; P., 36. ' "

CigHooOoNo Phenylaminoacetyltropeinc, and its dihydrobromido and di-

picrate (Jowett and Pyman), T., 1025.
CifiHwOjN.) a-Hydroxy-j3-2-py ridylpropionyl tropcine, and its salts

("Jowett and'PYMAN), T., 1024.

16 IV

CifiHgO-^NaBP-. 2':4':6'-Tribromo-4-nitro-2-benzeneazo-a-naphthol (Mit-

chell and Smith), T., 1436 ; P., 209.
2':4':6'-Tribromo-2-nitro-4-benzeneazo-a-naphthol (Mitchell and Smith),
T., 1436; P., 209.

CifiHaOeNoClo 5:8-Dichlorodinitro-l:2-dimethylanthraquinone (Harrop,
XoRRis, and Weizmann), T., 1315.

CisHr,04NC1.2 5:8-Dichloronitro-l:3- and -l:4-diniethylanthraquinone
(Harrop, Norris, and Weizmann), T., 1317.

Ci^HnOoNBr., Dibromodiketodiphenylpyrrolidine (Ruhemann), T.,
1605.

C]r,HnO.,NS 2:4-D ik eto-3-ph en yl-5-bcnzylidenetet rally drothiazole (Ru-
hemann), T., 120.

Ci.;HiiOaNS 2:4-D ik e to-3-ph en yl-5-salicylidenetetrahy drothiazole (Ru-
hemann), T., 120.

Cj«HiiO:,N.,S l:3-I)ipheuyl-2-thiovioluric acid (Isherwood), P., 121 ;
(Whiteley and Mountain), P., 122.

CigHiiO-CLBP 3:6-Dichloro-5'-bromo-2':4'-dimethyl-2-benzoylbenzoic
acid, and its sodium salt (Harrop, Norris, and Weizmann), T., 1316.

CjgHjoOvN.jS l:3-Diphenylthiobarbituric acid, preparation of (Isherwood),
P., 121 ; (Whiteley and Mountain), P., 121.

Ci«HuO.,N4CL 3:3'-Dichloro-4:4'-diacetyldiaminoazobenzene (Cain), T.,
716 ; P., "123.

CifiHip.O.-jN.iBl' B romo-o-car be thoxy benzene diazo hydro xy lam in o-2>-tolu-
ene (ISebhard and Thomp.son), T., 1121.

Cjr.HivOsNS Diethyl 4-keto-2-phenylimiuotetrahydrothiophen-3-di-

carboxylate (Ruhemann), T., 121.

Cjf,H](,ONCl 2^-Chlorophenyljminoca'mphor (Forster and Thornley), T.,
954,

227-*

FORMr[,.\ INDEX. 16 IV 17 III

CieHifiONCl ;>-CliIoroi.Iieii vlaniiiiiiuaiii phor (Forstkk and Tj(okni.ey), T.,
954.

CifiHiiONiBr Canii)hiirvl-/>-broino{>henyltriazen (Fokster and Garland),
t., 'J065.

CifiHoflONJ ;w-Methoxybeuzeueazodiinothylaniliii«f methiodide (Hevv-
iTV and Thomas), T., 1298 ; P., 190.

CibH.hiO'NCI Phenylchloioacct vl troi)oiiu', and its .siilts (Jowktt and
Py.man), T., 1024.

CjfiHovO-NS /-Mentliylaniine bunzenesiil pliDnato (Kii'riNG and Martin),
t., 193; P., 66.

CifjHo^tO^SSi rf^Benzvlethyl]iro]iyli,wl)utyl.siIicauesnl phonic acid, and
its salts (Ku'i'iNd and Davis), T., 69 ; P.," 9.

16 V

CifiHiftOsNBr.jS I')ietliyl-5-dil>romo-4-keto-2-phenyliininototraliydrolhio-
i)licii-li-dicarboxyIate (Ruhk.mann), T., 122.

Ci7 Group.

CirHioOg Dimothylrhein (Robinson and Slmonsen), T., 1093 ; P., 76.

Rhein ethyl ester (Robinson and Simonsen), T., 1092 ; P., 76.
C17H14O4 Chrysophanic acid dimethyl ether (Ti'tin and Clewrr), P.,

302.
C17H17N 2:3:7:8-Tetraniethylacridine, and its aurieidoride and platiniclilor-

ide (SexVIEK and Comiton), T., 1626 ; P., 220.
C17H00O5 o-Aldehydophenyl hydrogen cainphorate, and its rotatory

power (Hiluitch), T., 337.
Ci7H.>204 o-Tolyl hydrogen camphorate, and its rotatory power (Hilditch),

t., 337.
C17H08O8 Etliyl pentane-o55€-tetracarboxylate (DoBSoN, Ferns, and Per-

kin), T., 2011 ; P., 263.
C]7H280g Ethyl 5-methoxybutane-ao77-tetracarboxylate (Perkin and

Simonsen), T., 1171.

17 III

CnHii04N 2:3-Diketo-4-phenyl-r)-piperonyl pvrroline (Ri'HEMANn), T.,

1608.
CnHnOjCl Dimethylrhein chloride (Robinson and Simonsen), T., 1094 ;

P., 76.
Ci7Hi.-jON Salicylidenc-a-naphthylamine (Senier and Shephkard), T.,

443.
C17H13O0N Phenylpropiolylphenylacetamide (Ruhemann), T., 991.
Cinnamoylmaudelonitrile (Francis and Davis), T., 1408.
a-Benzoyloxy-7-phenyh'.TOcrotononitrile (Francis and Davis), T., 1406.
Salicyl-a- and -;3-naphthalide (Senier and Shepheard), T., 444, 445.
2:3-Diketo-4-plienyl-5-o-tolylpyrroline (Ruhemann), T., 990.
2:3-Diketo-4-phenyl-5-»i- and -;j-tolylpyrroline (Ruhemann), T., 1606.
C17H13O3N 2:3-Diketo-4-phenyl-5-anisylpyrroline (Ruhemann), T., 1607.
^-Acetoxybenzaldehydeindogenide (Perkin and Thomas), T., 799; P.
125.
CnHr^OjN Dimethylrheinamide (Robinson and Simonsen), T., 1095

P., 76.
CnHuOoN, Phenylpropiolvl-;j-tolylcarbaraide (Ruhemann), T-, 1609
P.. -220.

2275

17 III— 17 IV FORMULA INDEX.

C17H14O7N Dinitrohydroxy-1-o-, -m-, and -/J-carbethoxyphcuylmethj'l-

bcnziininazolc (Meldola aud Hay), T., 1041, 1042.
Cl-H,.^0•iN 2-Phenyl-5-veratryloxazole, aud its hydrochloride (Robinson),

f.."2172; P., 295.
CitHi-,04N ^)-Anisovl-j'-methoxymandeloiiitrile (FiUNCis and Davis), T.,

I'lOr.
Ci7H,fiO.-,N4 Dinitrohydroxy-l-(l:3:5-)t rime tliylplieuylnic thy llienzimin-

azole (Meldola and Hay), T. , 1017.
C|7H,,,0:;N Benzoyl-)3-amino-;8'-(*-tolyl<)xy2.wpropyl alcoliol (Boyd and

Knowlton), T.', 1805.
CpHooOiNo 0-, m-, and j)-NitroaniHno-(Z-methy lenecaniphor (Pope aud

Ke.U)), T., 182.
C17H..0O5S o-Aldehydophonyl camplior-;3-sulphonat c, and its rotatory

power (HiLDiTCH), T., 338.
C17H01ON Anilino-c?-methylenecaniphor, rotatory power of (Poi'E aud

Reap), T., 177 ; P., 19.
C^HoiOaN p-Metlioxyphenyliniinocamphor (Fou.steh and Thornley),

t., 962.
Cinnamoyltropeine, and its salts (Jowett aud I'yman), T., 1029.
C17H01N.J Methiodide of diphcnylpiperazine (UuxLor aud Jones), T.,

419."
CnHwOoN.) Camphorylphenyl-vf'-carbamide (Foksteii and Oakland), T.,

2061. "
C17H..1O3N.1 0-, VI-, and ;j-Nitrobenzobornylamidc (Frankland and Bak-

Kow),'T., 2035; P., 263.
C17H22O3N4 Caniphoryl-o-, -m-, and -2^nit rophenylmethyltriazen (Foiis-

ter and Garland), T., 2067.
C17H00O4S o-Tolyl caniphor-)3-sulphonate, aud its rotatory power (HiL-

DITCH), T., 338.
CnHo^ONj Camphorylphenylmetliyltriazen (Forster and Garland), T.

2066.
CnHo^jOgN 27-Methoxyphenylaminocamphor » (Forster and Thornley),

f., 952.
Ci7H2;jOoN3 Camphoryl-j;-methoxyphenyltriazen (Forster and Garland),

T.,''2064.
C17H23O3N a-Hydroxy-^-phenylpropiouyltropeine, and its salts (Jowett

and Pyman), T., 1023.
Atropine, resolution of, aud its aurichloride, auribromide and picrate (Barrow-
cliff, and Tutin), T., 1966; P., 256.
c?-Hyo8cyamine, auribromide ( + H.,0) aud picrate (Barrowcliff and Tutin),

T., 1976 ; P., 257.
C17H23O4N Atroglyceryltropeine, aud its salts (Jowett and Pyman), T.,

1022.
C17H23N2I Methiodide of diphenyldimethylethylenediamine (Dunlop

and Jones), T., 418.

17 IV

C17H12O3N4S )3-Naphthalenesulphonyl derivative of l-hydroxj'-S-phenyl-

tet'razole (Forster), T., 189 ; P., 25.
C17H13ON0BP Bromo-o- and -'/«-tolueueazo-;3-naphthol (Gerhard and

Thompson), T., 1120.
CnH220N3Bp Camphoryl-;j-bromoplienylmethyltriazen, and its salts

(t'oKSTER and Garland), T., 2070.
C17H23O3NS Camphor-j8-sulphonyl-7>-toluidide, and its rotatory power

(HiLDITCH), T., 338.

2270

FORMULA INDEX. 17 V 18 III

17 V

Cj-H.jO.NClBr Mcthohvomiile of pli uiiy Ic h loioacctyl tropcine (JowETT
aii(f Tyman), T., 1024.

Ci8 Group.

CihH„jO.. Naphthaccneqiiinonc, derivativos of (llAUiior, Nnitiiis, .mil Weiz-

MANX), T., 279; P., 33.
CisHijOfi Tiiinetlioxycouinaroiio/.sououiiiarin, and its liydiolnomidc (1'ekkin

and KoiilNSoN), T., 401.
CisHiA Xanthoeiidol (Tutin and Clewer), T., 84 ; P., 12.
C|sH,.-,N 7-Cyano-;8e-diphenyl-AP5-pcntadiene (Hawokth), T., 487.
CisHiiiOv Lactone of li vdroxytrimethoxybenzoincarboxylic acid

(Pkkkin and Robinsox), T., 405.
CimHisO.j o-Di'syh'sobutyric acid, formation of (Gray), T., 2148.
Cj^HisOg Hydroxytrimethox3'benzoincarboxylie acid (Pkiikin and

KoiiiNsoN), T., 404.
CisHisNo 3-Imino-o-cyano-o7-di-o-, -«(-, and -yj-tolylpropanc (1>kst and

TiioKPE), T., 265 ; P., 28.
6-o-Tolyl-l-metli vl-5:7-n apiitliylenedianiine, and it.s diliydrochloridc

(BE.ST and Tiiokpe), T., 266 ; P., 29.
6-?/(-Tolyl-2-methyl-5:7-naplithylenediamine, and its dibydrochloride

(Best and Tiioki-e), T., 269 ; P., 29.
7-p-T o 1 y 1-2-m e t li y 1 -6: 8 -n a p h t h y 1 e n e d i a m i n e, and its dihydrocliloridc (Best

and TiiOKi'E), T., 272 ; P., 29.
CigHisNs Bisbenzeneazophenylenedi amino (Bismarck-brown), rate of

formation of (Veley), T., 1189; P., 175.
CiijHonO^ Substance, from oxidation of laudauosine (Pyman), T.,'1269.
CjsHortOi Menthyl v-mandelate, partial raeemisation of, and llie /BdA- and

/B/A-salts and their solubilities (Fixdi.ay and Hickmaxs), T., 1386 ; P., 196.

18 III

Ci8Hf,03Cl4 7:8;9:10-Tetrachloro-l-hydroxyn apli tliacenequinonc (Har-
nor, Nonius, and Weiz.maxx), T., 287.

Ci,sHfi04Cl4 7:8:9:10-T e t r a c h lo r o-l:6-diliyd roxynap li t haceneq ui none
(Haiuiop, Norkis, and Weizmaxx), T., 287.

CisHsO^CL 7:10-D i c h 1 o r o-1-hydroxynaphthacenequinone (Harrop,
Nonii'is, and Weizmann), T., 283.

Ci8HH04Cl.> 7:10-Dichloro-1:5- and -l:6-dihydroxynapli tliaccnequinone
(Haiieoi', Norkis, and Weizmaxx), T., 283, 284.

Ci8H«04Cl4 3:4:5:6-Tetrachloro-r-hydroxy-2-/3-naphthoyl ben zoic acid,
and its sodium salt (Hakrop, Norris, and Weizmaxx), T., 286.

Ci8Hin04CL 3:6-Dichloro-l'-hydroxv-2-)3-naphtlioylbenzoic acid (Hak-
rop, Norris, and Weizmaxx), T., 282.

CjsHioOoN., Hydroxya/wsafranone, preparation of (Hewitt, Newmax, and
AVixmIll), T., 581 ; P., 86.

C,sH,.AAs.2 Resorcinyl arseuite (Laxg and Wooi)Hou.se), P., 199.

CjsHigOjN-, 4-Nitro-2-benzeneazo-a-naphtliyl acetate (Mitchell and
Smith), T., 1435 ; P., 209.
2-Nitro-4-benzeneazo-a-naphthyl acetate (Mitchell and Smith), T.,
1433 ; P., 209.

CigHiaOjN jo-Acetoxy-w-phthaliminoacetophenone (Tutix, Caton, and
Haxx), T., 2119.

CisHisOfiBP Bromotriraethoxycoumaronowocoumarin (Perkix and Robin-
sox), T., 403.

2277

18 III 18 IV FORMULA INDKX.

CisHuON-. Methylciieplieiivl-a-iiaplitliylcarbaniiile (Seniki; and Shei'-

HE.\iu>), T., 504.
C1SH14ON4 Bcnzoneazobenzeiieazoplienol, dilivdroclilm-irle (Hewitt and

' Thole), T., 1396; P., 208.
CisHuOsN4 Diuitroacetoxy-l-o-, -m-, and -y)-acetox yi)licii ylmctli ylbcnz-

iminazole (Melpoi-A and Hay), T., 1044, 1046.
CisHiflON 2-Hvdroxv-a-naiilitliylidene-;/(-toluidine (Semeu and Shep-

HEAiU)), T.,-1954. ^
CisH,riOjN Cinnamoyl7)-niethuxymaudi'l(initrile (Fhancis and Davis),

T.,'l40S.
C.HiAiSb Phenyl antimonite (MacKey), T., 60S ; P., 98.
CisHliOtN Substance, from cliloro.x3'lonino and hydri(xlic acid (Auld), T., 967.
CisHi^ONo s-ji)-Tolvl-a-naph thvlcarbaniide (Sexier and Shepheard),

T., 55-2.
CisH,60N4 Phenosafraninc, constitution of (Hewitt, Newman*, and Winmill),

T., fu7 ; P., 86.
C)sHi60:iN2 3-K e t o--i:5-d i-//-nictlioxydipli euyl-3:4-d i h y d r o-l:4-d i azine,

and its hydrochloride and picrate (McCcimbie and Pat.ry), T., 588 ; P., 95.
Ci«Hifi05N4 Substance, from phenylhydrazine and oxidation products of mucic

acid (Ferraboschi), T., 1249.
CisHisOSi Triphenylsilicol, action of fuming sulphuric acid on (Kipping and

Martin), T., 489 ; P., 66.
Ci^HjvON 7-Cyano-6-liydroxy-^€-diphenyl-A|3-pentene (Hawurth), T., 488.
Ci^HnOjN Benzoylcumylglycollonitrile (Francis and Davis), T., 1406.
C|.iHnO:iN 2-Benzyl-5-veratryloxazol6 (Robinson), T., 2173; P., 295.
CisH,-04N 2-Benzovlamino-5:6-dimethoxy-]-hydrindone (Robinson), T.,

2173 ; P., 296.
CisHjsOsNo Monoanilide of l-phenylpyrrolidine-2:5-dicarboxylic acid

(Le Sueur), T., 278.
C]>jHi904N co-Phen vlacetylarainoacctoveratrone (Robinson), T., 2172;

P., 296.
CimHo^ON Methylanilino-r^methylenecamphor, lotatory power of (Pope

and Read), T., 179.
y)-Toluidino-rf-methylenecamphor, rotatory power of (Pope and Read),

T., 177; P., 19.
C]sH.»OoN ^J-Ethoxyphenyliminocaniphor, and its hydrochloride (Forster

and'TiioRNLEY), T., 952.
CisHo^ON 0-, /«-, and ^;-Toluobornylamidc (Frankland and Barrow), T.,

2040 ; P., 263.
Ci^Ho50->N-. Camphoryl-7;-methoxyphenylmethyltriazen (Forster and

Garland), T., 2069.
C.sHiAN Senecifolidine, and its salts (Watt), T., 475 ; P., 68.
Ci,H2fiO,;N2 Hydroxylamino- derivative of 7?-ethoxyphenyliminocamphor

(Forster and Thornley), T., 952.
C]8H26N2l2 Dimethiodide of diphenyldimethylethylenediamine (Dun-
lop and Jones), T., 418.
Ci.RvjOsN Senecifoliue, and its salts (Watt), T., 469 ; P., 68.

18 IV

Ci«H704Cl4BP 3:4:5:6-T e t r a ch lo r o-4'-b r o m o-l'-hyd roxy-2-;8-naph th oyl-
benzoic acid, and its sodium salt (Harrop, Norris, and Weizmann),
T., 287.

Cj^HnOsNClo 7:10-Dichloro-6-a mino-l-h ydroxynaphthacenequinone
(Harkop, Norris, and Weizmann), T., 284,

2278

FORMULA INDKX. 13 IV \g l\

CmHiiO^CLBp 3:6-D i c li 1 o r ()-4'-b r o mo-l'-Iiyd ioxy-2-)8-iiaiili tlioyl ben zoic

acid (Haurop, Nokris, and Weizmann), T., 283.
C|sHi.;O..NS 2:4-D i k e to-3-p h enyl-5-cinnamy 1 idene tetra )i vdiotliiazolo

(KlTUKMANN), T., 120.

CisH|.;0,-,N,Hg" 4-X i t r o-2-b enzeneaz o-a-n a ji h t ii o 1 in <■ r r n r i a c ot ato

(IMitchkll and Smith), T., 1435 ; P., 209.
2-Nitro-4-bcnzeneazo-a-naphthol niurcuriaectate (Mitciiki,i, and Hmith)

T., 1433; P., 209.
CjsHuOiNoHgr /S-Benzeneazo-o-naph tlinl iiier(Miriat:ctate (Mitchkii, anil

Sjirni), T., 1434; P., 209.
Cl^H|,i04NSb Triphenylstibine liydroxynit rate (Mokcan, Mickij/hiwait

and WiiiTliY), P., 302.
C|sH|sON:;As Trianiinotriplicnylarsine oxide, and its liydrocliloiiilr

ami platinichloiide (Mokcan and JIickletiiwait), T., 1474 ; P., 212.
C|sH-.O.jNI Benzoyllioidenine inethiodide (Hakceu), T., 2197.
CisH.iOjNS Caniphoi-j8-sulplionyl-;*-acetylauilide, and its rotatory ijowxt

(HiiiiiTrn), T., 339.
CisH.^OoNBp Methobroniido of cinnanioyl tropni no (Jowett and Pymax)

T., io;so.

C,sH.j.-,0:!NS C a ni ]i li o r-/3-sulplionyl-y)-ethylphciiylaniide, and rotatory
powtf of (HlLDITl'H), T., 339.

CmHoiiO-NBr ^lethobroniide of odiydroxy-)3-piicny 1 propionyl tropci ne

(JowKTT and Pyman), T., 1023.
CisHocO^NEp Methobromide of atroglyceryl tropuine (JciWETT and

Pyman), T., 1022.
CmH.K,0-,NS Trupinone rf-campliorsulpliouate ( + H.,0) (Hakiiowci.ikf and

tuTiN), T., 1973.
CisH-iiO^NS Tropine (^camphorsuliilionate (Bahruwci.ifk and Trnx), T.,

1970; P., 257.
<|/-Tropiue fZ-cani pliorsulplionate (Bakiiowclii-f and Trnx), T., 1971;

P., 257.

18 V

CmH,oO=,NBpS i^-Trojiine ri?-bromocampborsiilphouate (+H,0) (Barrow-
ci.iFF and TniN), T., 1971 ; P., 257.

Ci9 Group.

t5-N-H
CigHiiNi I -Dimiiiiacridinc, and its salts (Senieii and CuMiTux), T.,

5-CH-5
1629; P., 220.
CiqHi.,0^^ Diacetylrhcin, preparation of (Rdbixsox and Simoxsen), T., 1090;

P".,76.
Ci(,Hi40q 7-Metlioxy-5:6-m e t li y 1 e n edioxy-2-piperonylidene-l-liyd rind-
one (Pekkix, Robixsox, and Thomas), T., 1983.
Trimethoxy-a- and -3-brazan(iuinone (PERKixand Robixson), T., 394, 398.

N-a N-)3

C|.,Hj-,N 9:10-Dimet]ivlplieno- | - and - | -na[)ht liacridi ne, and their

CH-)3 CH-a

salts (Sexier and Comptox), T., 1627, 1628 ; P., 220.
CigHigOs a- and -/3-Anhydrotriraethylbrazilone, constitution of (Perkin and

R(jBixsox), T., 381 ; P., 31.
CigHjhOe Dimethylrhein ethyl ester (Robixsox and Simoxsex), T., 1093 ;

P., 76.
CigHigOv Tetrametboxyeouniaronowocoiunarin, iiydrobromide of (Pekkix
and Robixsox), vT., 407.

2279

19 11—20 II FORMULA INDEX.

C19H18O0 Aiiliydroace tonebenzil, direct proofs of tho presence of the liydroxyl

group in derivatives of (Gkay), T., 2131; P., 218; isomerides of, and its

derivatives (Gkay), T., 2138 ; P., 218.
4-Methoxy-3:4-diphenyl-2-metliyl-A''-c//c/opentcnone (Quay), T., 2135.
3:4-Diplicnyl-5:5-dimethyl-A--c//c/(>pcntcn-]-oue-2-ol (Quay), T., 2146.
Cj^HisOj J87-D i p h e n 3' 1-aa-d i ni e t li y 1 b u t y r o 1 a c 1 0 n e-7-c a r b 0 X y 1 i c acid

( + H.p), and its silver salt (Quay), T., 2148.
CioHifiOe Trimethvlbrazilone, constitution of (Pei;kin ami Robinson), T.,

381 ; P., 31.
CipHisO- Lactone of tetraniethoxybenzoincarboxylic acid (PEnKlN and

Robinson), T., 405.
Eriodonol, (and +H.p) (Trnx and Clewer), T., 86 ; P., 12.
CiflHoflO 3:4-Diplienyl-5:5-dimethylc!/cZopentenone (Gray), T., 2147.
CigH-xiO-i Ethyl o-henz'oyl-/3-phenyl/sobutyrate (Hope and Perkin), T.,

2046.
C19H20O5 a-Hydroxy-a3-diphenyl-77-dimcthylglutaric acid, sodium salt

(Gray), T., 2150.

19 III
C19H13O0N Benzoyl-;3-nai)h thy Igly colic nit rile (P^rancis and Davis), T.,

1406.
CjgHisOoN Lactone of 7-cyano-e-hydroxy-;8e-diphen3']-A«-pentene-7-carb-

oxylic acid (Haworth), T., 487.
C19H15O5N Diacetoxybenzaldehydeindogenide (Perkin and Thomas), T.,

798 ; P., 125.
C19H15O7N Nitro-a-anhydrotrimethylbrazilone (Perkin and Robinson),

T., 393.
C19H16O3N0 m-Carbethoxybenzeneazo-j3-naplithol (Gebhard and Thomp-
son), T., 1121.
CjnHnOoN 2:3-Diketo-4-phenyl-5-cumylpyrroliue (Ruhemann), T., 1607.
C19H17O3N 7-Cyano-e-hydroxy-y8e-dipheuyl-Aa-pentene-7-car boxy lie acid

(Ha'vvorth), T., 487.
C19H18ON2 Diaminotriphenylcarbiuol, rate of reaction of, with acid and

alkali (Sidgwick and Rivett), T., 899 ; P., 3 24.
CJ9H19O2N Oxime of )3;8-diraethylanhydroacetonebenzil (Gray), T., 2147.
C19H01ON Oxime of 3:4-diphenyl-5:5-dimethylf2/cfopeutenone (G]:ay), T.,

2148.
C19H01O2N Benzoyl derivative of 3-cyano-l:2:4-trimethyl-4-ethyl-A':'^-cycZo-

hexadien-6-ol (Gardner and Haworth), T., 1960.
C19H24O4N4 Methylglucosazone (Irvine and Hynd), T., 1225.
C19H25ON d- and ^a-Pheuylethylamino-c?-methylenecamphor (Pope and

Read), T., 172, 174.

19 IV
CjgHieON.-jP Phenyliminophosphorylphenylbeuzamidine (Titherley

and Worrall), T., 1154 ; P., 150.
Cj9Hi602NiS l:3-Diphenyl-5-isopropenyl-2-thiobarbituric acid (White-
ley and Mountain), P., 121.
C19H1SO2N2S l:3-Diphenyl-5-i.sopropyl-2-t]iiobarbituric acid (Whiteley

and" Mountain), P., 121.

C20 Group.

a-N-6
C20H10N2 I -Naphthaquinacridine, and its aurichloride (Senier and

/3.CH-5
CoMKroN), T., 1631 ; P., 220.

2280

FORMULA INDEX. 20 II 20 III

j8-X-G
C..||H,..N.. I -Naph thiiiiiii iiai.ruliiic, ami its salicylate (Sknikk and

a-CH-5

CoMPTON), T., 1632 ; P., 220.
C.j,iH|,,07 Tetrainethoxy-a-brazaiiiiuinono (Pk.iikin ami Robinson), T., 399.
C.„H|.,N-, Benzeiieazobenzenea/odiinethy lanilinc, and its hvdrocliluride

(Hewitt and Thole), T., 1395 ; P., 208.
C.,„H..,|0.. 4-E t h 0 .X y-3 :4-d i p li 0 n y 1-2-m e t h y 1- A--r//'-A/p e n t e n o n e (G K.\ Y ), T. ,

2134.
2- M e t li 0 X y- 3 :4-d i \> h e ii y\-'):')-d i ni e t li y 1- A-'-ci/(7(/p e n t e u o n c (C! it.w), T. ,

2147.
C..,|H.>,0-i Ethyl a-benzoyl-/8-phen vl-a-ethylpiopionate (HorK and PEit-

KiN), T., 2050.
C,|H..,;0-, Eugenyl hydrogen caniphorate, rotatory powt-r of (Hilditch),

t., 336.
(■^■((Eugenyl hydrogen caniphorate, and its rotatory power (Hll.DlTCH),

T., 337.
ChiH..H04 ^Menthyl </-, Z-, and (//-acetylniandclate (McKenzie ami HuM-

imuEs), T., 1109, 1111.
Cj,iH.jsOg Cy no toxin (Finxemore), P., 77.

20 III

Co,iHi404N.> o5-Dicyano-)37-dipheuyl-A^-butene-o5-dicarboxylic acid, and

Its potassium and sodium salts (Hawouth), T., 486.
C.|,Hi,;0N.2 3-Keto-2:5-distyryl-3:4-dihydro-l:4-diazine, and its hydrochloride

(MeCoMBiE and Parry), T.^, 589 ; P., 95.
C..,jH,oO..No Disalicylidene-2J-phenylenediamine (Senier and Shei-heard),

T.,"l950.
Co,|Hi,,0oN4 Benzeneazobenzeneazopheny 1 acetate (Hewitt and Thole),

T.,"l397 :. P., 208.
Cj,|H,707N Nitro-a-anhydrotrimeth vlbrazilone methyl ether (Perkin

and Robinson), T., 394.
C,.,H|,,04P Phenyl di-^-tolyl phosphate (Luff and Kipping), T., 2002.
CHjH..i04N l:2-Dihydro])apaverine, (and +3H.,0) and its hydrochloride

(Pyman), T., 1620; P., 217.
C2oH.j,^04N Tetrahydropapaverine, and its salts (Py.man), T., 1614 ; P., 217.
C>iiH..,jOgS Eugenyl camphor-;8-sulphonate, and its rotatory power (Hil-
ditch), T., 338.
woEugenyl caniphor-)3-sulphonate, and rotatory power of (Hilditch),

T., 3.38.
C..„H.704N Dihydroxydi-o-tolyloxydipropylamine (Boyd and Knowl-

ton), T., 1805; P., 235.
CjoHo^OiiN Amygdalin, hydrolj-sis of (Auld), T., 927 ; P., 62 ; (Walker and

Krieble), T., 1369 ; P., 203.
/.wAmygdalin, experiments on (Tutin), T., 663 ; P., 118.
CjoHo^OsHg":; Substance, from action of potassium hydroxide on Co„H4.,03LHg4

(\Marsii and Struthers), T., 1787.
C,,H:;„0:;Hg.2 M ercur icam p hor oxide (Marsh and Struther-s), T., 1785.
C...oH:i„04No Fumaroyltropeine, and its hydrocliloride and hydriodide (Jowett

and Pyman), T., 1026.
CjiH-jOjP Dicampliorylphosphinic acid (Morgan and Moore), P., 310.
Cj,)H::oO,;N.2 Tartryltropeine, and its salts (Jowett and Pyman), T., 102C.
C.,„H;;OoN Z-Mcnthylamine d-j8-phenyl-a-meth vlpropionate (Pkjkard

and" Yates), T., 1019 ; P., 152,

2281

20 IV— 21 IV FORMULA INDEX.

20 IV

C-xiHhO.jN.jBPo 5 :r>'-U i b 1- o 111 u d i s a 1 i cy 1 i d e n e-p-^ li e ii y 1 o ii e d i a in i n e (S enier
aiul SiiKPHE.vUD), T. , 1953.

C..i,H„;0N.,Br4 3-Keto-'2:5-distyryl-3:4-dihydro-l:4-diazine tetrabromide
(Mt'L'oMBiE and Pahry), T.. [>90.

Coi Group.

CoiHifiOs Diacetylrhein etliyl ester (Robinson and Simonsen), T., 1092;

P., 76.
CiH.^Oj 4-A cet o X y-3:4-d i pli en yl-5:.'i-dimetlivl-A--(v/cAjpe lite none (Gray),

t., 2137.
C-i H._>oOio Quercimeritrin, from Gossiipium Jicrbaceam, and its potassium salt

('Perkin), T., 2185 ; P., 291.
j'scjQuercitrin, from (Jossyjmi.iii herlaceum (Perkin), T., 2190 ; P., 292.
Co,H2oOi3 Gossypitrin, from Gossypmm lierhaceum (Perkin), T., 2189 ; P., 292.
Co,H..4Nij Bistolneneazotolylenediamine {Vesuvine), rate of formation of

(Yeley), T., 1197 ; P., 175.

21 III
CoiHiAN 3:4-Dibenzoyloxybenzonitrile (Ewix.s), T., 1488.
CoiHirOyN Carbanilido-Z-benzoin (Wren), T., 1586.
CoiHivO^N Nitroaeetyl-o-anhydrotrimethylbrazilone (Perkin and

Robinson), T., 393.
Nitroacetyl-;3-anhydrotrimetliylbraziloiie (Perkin and Robinson), T.,

397.
C.,iH,i,OjN Ethyl a-cyano-;8-benzoyl-a-styrylpropioiiate (Haworth), T.,

484.
C91H20O4N2 Benzoyl derivative of etliyl 2:6-dicyano-l:l:5-trimethyl-A^:'-

p?/cMiexadien-3-ol-6-carboxylate ( + H„0) (Garpner and Haworth), T.,

1959.
CfiHoiOsN Oxime of 4-acetoxj'-3:4-diplienyl-5:5-dinietli3'l-A--c(,rZopenten-

one (Gray), T., 2147.
CaiHoiO;,Sb 0-, in-, and ^;-Tolyl antimonite (MacKey), T., 608 ; P., 98.
C.nHgjON j8-Naphthylamino-(^methylenecamphor, rotatory power of

(Pope and Read), T., 178 ; P., 19.
C01H.57ON ac-T e trail V d r o-;3-n a p h t h y 1 a m i n o-f^m c t li y 1 e n e c a m p h 0 r (Pope

and Read), T., 180.
C.>iH.v04N Laudanosine, oxidation of (Pyman), T., 1266 ; P., 190 ; hydriodide

of (Pyman), T., 1616.
CoiH.iOoN /-Mentliylamine rf-A''-diliydro-2-naplitlioate (Pigkard and

Yatks), T., 1014 ; P., 152.
C.,iH-,oO„N Z-Mcnthylamine (Z-i)henylallylacetate (Pickard and Yates),

f.,"'l016; P., 152.
C^iH340.2N2 5-Iniino-2-cyano-l:3-dimethyl-6-amyl-3-hexyl-A*-ryc'Zoliexene-

2-carboxylic acid (Gardner and Haworth), T., 1964.
C.<iH>502N Z-Menthylamine (/-^-phenyl-a-ethylpropionate (Pickard and

Yates), T., 1018 ; P., 152.
^Mentllylamine a-phenylvalerate (Pickard and Yates), T., 1017 ; P.,

152.

21 IV

C:;iHi,;0;.N^S Etliyl 3-0 y a tt 0-4 -k c 1 0-2- jj li 6 11 y 1 1 m i n 0-5 -b e H z y 1 i d c u c 1 6 1 T 3-
iiydrothiophen-3-carboxylate (Ruhemann), T., 121.

2282

I

FORMT'L.V IXDEX. 21 IV 22 111

C.iHirtOtNjS Pyridine /3-l:3-JiiihL'ii vl-2-llii(»vi<)liuate ;\Viiii i;i,kv and

Mountain), P., 122.
Cji Hi.jOjNoS Ethyl 3-c y a n o- 4 -k e t o-2-p li 0 n y 1 i m i n 0-5-s a 1 i c y 1 i d e n e t e t r a-

hyilrothiophen-3-carboxylate (Ruheman'n), T., 121.
C:.iHoo03N4S Piperidini! 3-l:3-diplienyl'J-thio violurate (Wkiteikv and

Mountain), P., 122.

Ct2 Group.

C.,Hi,;0.> cw-o/8-Dibenzoy Ist^'iene, refiuLtion of, and action of iwaniylatniiie on

^.S.m'edley), T., 219 ; P., 17.
C.-.HisO.) Dibenzylphthalide, formation from niaguesiiun bt-nzyl chloride and

diethyl phthalate (Shibata), T., 14r.4.
CijHisOy Triacetylchrysoeriol (TuTiN and Cleweu), T., S'i ; P., 12.
C.H.rjNs o-Tolueueazo-o-tolueueazodimuthy Ian il ine, and its liydrochloride

("Hewitt and Thole), T., 1396 ; P., 208.
Cj:)H.i,<04 iMenthyl piperate, and its rotatory power (IIii.ditch), T., 1572 ; P.,

214.
C-.Hi„04 Menthyl a&- and /S^-hydropiperate, and their rotatory powors

(HiLDircii), T., 1572 ; P., 214.
C^H(.i04 Menthyl pi[ierony Ibuty rate, and its rotatory power (HiLinTCJi),

T., 1573 : P., 214.
CjjHijjO^ Dinicnthy] oxalate, and it,s rotatory power (ilii lumi), T., 1579;

P., 214.

22 III

C;^H,jO^CL 7:10-Dichloro-l:6-diacetoxy naphthacenei[uinone (Hakrop,

NoRKis, and Weizmann), T., 284.
CHnON^j Phenylhydrazone of diketodiphenylpy rroline (Kuiiemann),

f., 989.
C..H1-O4N a>-Benzoylamino-/*-benzoyloxyaceto[>henone (TrriN, Caton,

and Hann), T., 2120.
C .Hi<,0 N o-;>Benzoyloxy-.iy-benzoylpheny lethylaniine (Tutin, Caton,

and' Hann), T., 2123.
C.i;Hi,,04N Dibenzoyl derivative of ^-^-dihy droxy-j3-pheny lethylamine

(TuTiN, Catox, and Hann), T., 2121.
C.joHi.,09N Nitroacety l-o-anhydrotetranietliylha;niatoxy lone (Pekkin

and Robinson), T., 398.
Cj.jHooO.jN2 2:2'-Dimethoxydibeuzylidene-^^-pheny lenediamine, and its

hydrochloride (Senier and Siiefheaud), T., 1951.
2:2'-Dihy droxy-5:5'-dime thy Idibenzylidene-ju-phenylene diamine

(Senier and Shei'HEARd), T., 1953.
Cj..H..iONj oi- P h e n y 1 a c e t y 1 a m i n o a c e t o p he n o n e p 11 e n \ 1 h y d r a z o n e

('PtOBiNsoN), T., 2170 ; P., 295.
CjoHooO-.No D i ac e t y 1-6-o-t 0 1 v 1-1 -m e t h y 1-5: 7-n a p li t h y 1 e n e d i a m i n e ( Be.st

and" Thorpe), T., 267.
Diacetyl-6-7n-tolyl-2-methyl-5:7-na}ihth vlenedianiine (Best and

Thorpe), T., 269.
Diacetyl-7-i»-toly 1-2-me thy l-6:8-naphth vie ne diamine (Best ami

Thorpe), T., 272.
CooHaaOoNe Azoan tipyrine (Forster and Muli.kr), T., 2076.
CwHasOrN Chloroxylonine, from Chloroxylon swidenia, and its salts (Ai'Ld),

T., 966 ; P., 148.
C.iHo^OioN Tetra-acetyl-Z-mandelonitrile glucoside (Power and Moore),

T.. 259 ; P., 27.

2283

22 III— 23 IV FORMUr.A INDEX,

Cj^HnOjN .V-Etliy Itet rah vilrop!i]iavciine, and its picrato (Pyman), T.,

1741.
Cj-HsiOr.Sio Benzyliliethoxysilic}'! oxide (Martin and Kii'PiNo), T., 310.

22 IV

CooHioONjBPfi Bis-2':4':6'-tribroniobenzeneazo-a-naplithol (Mitciirll and

Smith), T., 1437 ; P., 210.
CooH].',04Nr,S 1 :3-D i p li e n y l-'2-t h i 0 a 1 1 o X a n-^j-n i t r o p li e ii y 1 h y d ra z o n e

(WiiiTKi.FA' and Mountain), P., 122.
Ci>Hj60..N4S 1 :3-D i p h e n y 1-2-t h i o a 11 o x a n phenyl li y d r a z o ii e { Wiuteley

and'MouNTAix), P., 122.
C.«Ho203NP a- and $-dl- and a- and )3-fZ-Hydrindamide of ph enyl-j»-toly 1-

phosphoric acid (Luff and KirriNO), T., 2006.

C-i Group.

C.jiiOaiOg Diacetoxytriniethoxy-a-brazan (Pkrkin and Robinson), T., 396.
CsHsoOj Glycerol dithymyl ether (Boyd and Maule), T., 1808 ; P., 23.^).
C..1H40O4 Dimenthyl malouate, and its rotatory power (Hiluitch), T., 1579;
P., 214.
Ipuranol, isolation of, from Apocynum androsaemifoUum (Mooiie), T., 737:
P., 85.

23 III

C.j^HnOsNs Phenylliydrazone of 2:3-diketo-4-phenyl-5-piperonylpyr-
rolidine (Ruhemann). T., 1609.

C03H1SO3N0 Pienzamide of y3-benzoylaminocinnamic acid (Ruhemann),
T,, 988.

Cg-HiaONs Phenylliydrazone of 2:3-diketo-4-phenyl-5-o-tolylpyrroline
(Ruhemann), T,, 991.
Phenylhydrazone of 2:3-diketo-4-phenyl-5-//i-tolylpyrroline (Ruhe-
mann), T., 1606.
Phenylliydrazone of 2:3-diketo-4-phenyl-5-^j-tolylpy rroline (Ruhe-
mann), T., 1607.

C^HofiONo Malachite-green (carbinol-form), rate of reaction of, with acid and
alkali (Sidgwick and Moore), T., 889 ; P., 123.

C.,vH280oN4 Caraphordiazodiphonylcarbaniide, and its isomeride (Fokstek
and" Garland), T., 2059.

CwHosON.) Bis(2-/3-niethylaminoethylbenzylidene)acetone, and its di-
hydri'odide (Pyman), T., 1750.

Cr-Hji04N iV-Propyltetrahydropapaverine, and its i)icrate (Pyman), T.,
1747.

23 IV

Co;iHi40:jNCl 7(10)-Chlorol0(7)-anilino-l-hydroxynapht]iacenequinone
(Harkoi", N0RRI.S, and Weizmann), T., 285.

C:i)H,504N;iS l:3-DiphenyI-5-o-nitrobenzylidene-2-th lobar bit uric acid
"^ (Whiteley and Mountain), P., 122.

Co:;Hi602NyS l:3-Diphenyl-5-benzylidene-2-thiobarbituric acid (Whitk-
ley and Mountain), P., 121.

CjHigOaN^S l:3-Uiphenyl-5-benzyl-2-thiobarbituric acid (Whiteley and
Mountain), P., 122.

C.^HoiOsNS Diethyl 4-ke to-2-phenylini ino-5-benzyli dene tetraliyd ro-
th iophcn-3-dicarboxylate (Ruhemann), T., 122.

C.i.H.jiO,jNS Diethyl 4-k eto-2-phenylim in o-5-salicy lid en etetrahyd ro-
th ioplien-3-dicarboxy late (Ruhemann), T., 122.

2284

FORMULA INDEX 23 IV 25 III

C03H.J5O4NS Camplior-/3-sulplioiiyl-/)-beiizoylanilide, ami iDtatoiv iiowur of
(HiLDiTcn), T., 339.

CaiH;,._.0;,NP a- and /8-Z-Menthylainiile of pheny l-;»-tolyli)]i osphoric acid
(Luff and Kipping), T., 2008.

C04 Group.

C-.^HisO.. Beuzylideueanhydroacetonebenzil, isorneride of (Ghay), T.
214:3.

3:-l-DipheTiyl-5-benzylideiie-A2-ci/(7openten-l-one-2-ol, isomeric forms of
(Gk.\y), T., 2144.

CjjHonOio TriacetyLxanthoeridol (Tutin and Cleweu), T., 85 ; P., 12.

C..4H.,j04 2:6:6-Triacetyl-l:5-diphenylcj/c^oliexan-3-one (Ruhemann), T.,

114.
C^HifiOs Tetra-acetyl derivative of pinacone, from ^^-hydroxyacetoplienone

(TrnN, Caton, and Hann), T., 2122.
C..4H40O4 Dimenthyl succinate, and its rotatory power (Hii.niTcn), T., 1579 ;

P., 214.

24 III

C.j4H„iOtN2 Phthalylmandelonitrile (Francis and Davis), T., 1407.
C.jHi.iO.N'i Benzoylmethyl-;>-aminobeuzeneazo-;8-iiaphthol (Morgan and
Ai.corK), T., 1325.

Co^H.^NnAs Base, from arseiiious chloride and aniline (Morgan and Mickle-
thwait), T., 1474.

C..4H..r,0inN Ethyl nitrodiphenyltetracarboxylate (Crossley and Hamp-
sniKE), P., 163.

Co4H;>04No Di-^;-toluidine camphorate, and its rotatorj' power (Hilditch),
T., 337.
Phthaloyltropcine, and its salts (Jowett and Pyman), T., 1030.

24 IV

CaiHisOfiNgSs B e u z e n e-1 : 3 : 5-t r i s u 1 p h o n y 1 1 r i -^>-p h e n y 1 e n e d i a z o i m ! d e
(Morgan and Pickard), P., 300.

C24H)80sN4Hg Bisbenzeneazo-a-naphthol mercuriacetate (Mitchell and
Smith), T., 1435 ; P., 209.

Co4Ho404N.5As Triacetylaminotriphenylarsine oxide (Morgan and
5lii ki.ethwait), T., 1475.

Cl'4Ho406NbS3 B e n z en e-1 :3:5- 1 r i s u 1 p h 0 n y 1 1 r i-^J-p henylenediamine (Mor-
gan and Pickard), P., 300.

C05 Group.

CnsHisO 3:4-Diphenyl-5-benzylidene-2-methylen e-A^-cydo]} entenone

(Gray), T., 2136.
C25H30O4 ^Menthyl rf/-benzoylmandelate (McKenzie and Humphries), T.,

1112.
C25H44O4 Dimenthyl glutarate, and its rotatory power (Hilditch), T., 1579;

P., 214.

25 III

C25H15O3N Diphenylpropiolylbenzamide (Ruhemann), T., 987.
CojHoiOoNs Benzoylethyl-jj-aminobenzeneazo-jS-naphthol (Morgan and

Alcock), T., 1325.
C25H.WON2 Phenylbenzylhydrazide of benzylfurfuraldehyde (Fenton

and Robinson), T., 1336 ; P., 193.

2285 7 L

25 III— 26 III FORMULA INDEX

Co,H.>^0N3 Pheiiylhj'drazoiie of '2:3-diketo-4-phenyl-5-cumylpyrroliue

fHrnEMANN), T., 1607.
C25H04ON0 Phenylhydrazone of 3:4-di{>henyl-5:5-diiiietliyl-A2-c2/c^-

pi'nt'en-l-one-'2-ol (Gray), T., 2147.

Cj,r,H.!..0:{N2 Carbonate of 3-cyano-l:2:4-trimetliyl-4-etliyl-A^:'^-c2/cZoliexa-
dieii-6-ol (Gaudneh and Haworth), T., 1960.

25 IV

C25Hi60;tNCl 7(10)-Chloro-10(7)-?'-tolnidino-l-hydroxynaphtliacenequiii-

0111' (Hakrop, Norri.s, and Weizmann), T., 285.
C.i'.HisOoN.iS 1 :3-D i p h e n y 1-5-c i n n a m y 1 i d e n e-2-t h i 0 b a rb i t u r i c acid

(Whiteley and Mountain), P., 122.
CorHisOfiNS Benzoyltropeine c?-camphorsulphonate (Barrowcliff and

TuTiN), T., 1972; P., 257.
Benzoyl->j/-tropeine ^^camphorsulphonat e (Barrowcliff and Tutin),

T., 1972 ; P., 257.

25 V

C25Hi40fiNBpS Benzovl-4'-ti'opeine (Z-bromocamphorsnlphonate ( + 3HoO)
(Barrowcliff and Tutin), T., 1972; P., 257.

C06 Group.

CogHisO l:l-Diphenyl-3-phenylenephthalan (Shibata), T., 1454; P.,

209.
C.26H18O0 a7-Dipbenyl-7-l-naphtbylallene-a-carboxylic acid (Lapwortii

and'WECHSLER), P-, 307.
CogH.ioO;, 2-Acetoxy-3:4-diphenyl-5-bcnzyliden e-A~-cyclo]) entenone, iso-

nieric forms of (Gray), T., 2145.
4-Acetoxy-3:4-diphenyl-5-benzylidene-A^-c2/c^pentenone (Gray), T.,

2137.
CobHosOs Diethyl 6-ac6ty 1-1 :5-diphenylc2ycZohexan-3-one-2:6-dicar boxy 1-

ate, and its sodium derivative (Ruhemann), T., 112.
C06H40O4 Dimenthyl muconate, and its rotatory power (Hilditcii), T., 1571 ;

P", 214.
C08H44O4 Dimenthyl aj8- and 37-hydromuconate, and their rotatory powers

(Hilditch), T., 1572 ; P., 214.
C26H48O4 Dimenthyl adipate, and its rotatory power (Hilditch), T., 1572;

P., 214.

26 III

C26H20O3N4 Benzoyl-^-aminobenzene diazo-oxide (Morgan and Alcock),

t., 1327.
C26H.50O4N2 Trimethoxy-a-brazotoluquinoxaline (Perkin and Robinson),

t., 395.
C26H21O.2N5 DibRnzoyl-4:4'-diaminodiazoaminobenzene (Moroan and

Alcock), T., 1-326.
C26H26O6BP2 Dibromo-derivative of diethyl 6-acetyl-l:5-diphenylc?/cZo-

hexan-3-one-2:6-di car boxy late (Ruhemann), T., 113.
C26H..ii0nN Indican (Thomas, Bloxam, and Perkin), T., 824 ; P., 126.
C215H32O0N2 p-Phenylenebisiminocamphor (Forster and Thornley), T.,

955"
CQfJi:f2QnV[o Di-7?-aminoacetophenone cam ph orate ( + 1^H20), and its

rr.tatoiy power (Hilditch), T., 337.
C26H3e04N2 Ethyl o5-diethylanilinoadipate (Le Sueur), T., 278.

2286

FORMULA INDEX 26 IV 27 III

26 IV

C.>cH480,jN.jS.> Z-Menthylamine benzenodisulplionate (Kiri-INO and Mar-
tin), T., 492 ; P., 67.

26 V

CoGHjiiOaNSSi Z-Mentliylamiiie rf/-benzyletliylprojiyl/.vobutyl8ilicaue-
sulphouatc, (and +2HoO) (Kii-i-iNu and Davis), T., 74 ; P., 9.

Cor Group.

C27H24O2 4-E t ho xy-3:4-diphenyl-5-benzylidene-2-ine thy l-A--ri/t7open ten-
on 0 (Gray), T., 2135.

C_.7H.j,iOn Tetra-acetylei-iodonol (Tutin and Clkweh), T., 86 ; P., 12.

C..7H.TNi 6-Amino-5-o-tolyl-2:4-di-o-metliylbenzylpyrimidine (Best and
Thorpe), T., 266.

6-Amino-5-?/i-tolyl-2:4-di-??i-metliylbonzylpyriniidine, and its hydro-
chloride (Best and Thorpe), T., 268.

6-Amino-5-/»-tolyl-2:4-di-;>methylbenzyl-pyrimidine, and its hydrochlor-
ide (Best and Thorpe), T., 271.
C.27H44O Homoandrosterol (Moore), T., 740 ; P., 85.
C.27H44O4 Acid, from oxidation of cholesterol, (DorSe), T., 640 ; P., 88.
CotH^Os Cholestenone ozonide (DoRfcE), T., 643 ; P., 88.
C.-tHj^Ot Ozonide of acid CyjE^fi^, from cholesterol (Dori^e), T., 641 ; P., 88.
C.7H440n Ozonide of acid C27H44O4, from cholesterol (Dori^.e), T., 642 ; P., 88.
C-rjU^aO o-Cholestanol, action of ozone on (Dori^:e), T., 647 ; P., 88.

)3-0holestauone, action of bromine on (Dori^e), T., 648.

Cholesterol, chemistry of (Dor]5e), T., 638 ; P., 88.

Coprostanone, action of bromine on, and reaction of, with phenylhydrazine
(Dor6e), T., 648.

Phvtosterol, from Ecballium elater aiin iVowFAi and Moore), T., 1987 ; P.,
260.

Phytosterol, from bark of Prunus serotina (Power and Moore), T., 246 ;
P., 27.

Phytosterol, from wheat germ, action of ozone on (Dori^e), T., 649.
C.7Hj,;07 )3-Cholestanone ozonide (Dori^^e), T., 645 ; P., 88.
C^tHjcOs Coprostanone ozonide (Dori^e), T., 647 ; P., 88.
C27H48O Coprosterol, chemistry of (Dori5e), T., 638; P., 88.
C.>7H4804 Dimenthyl pimelate, and its rotatory power (Hilditch), T., 1579;
P., 214.

;8-Cholestanol ozonide (DoRf^E), T., 644 ; P., 88.

Coprosterol ozonide (DoRte), T., 645; P., 88.
C27H48O7 »|/-CoprosteroI ozonide (Dor^e), T., 646 ; P., 88.

27 III

C07H02O5N2 Tetramethoxy-o-brazotolu([uinoxaline (Pep.kin and Robin-
son), T., 399.

C.^Ho40..N4 D icarbanilinodiphenylmethylene diamine (Senier and
Shepheard), T., 496.

Co7HaiN4S2 Dithiocarbanilinodiphenylmethylenediamine (Senier and
Shepheard), T., 498.

C27H27O5N A"-Benzoyl-l:2-dihydropapaverine (Pyman), T., 1621.

C27H2SO5N iV^-Benzoyltetrahydropapaverine (Pyman), T., 1617; P., 217.

C27H33O6N5 Brucine a- and /-a-triazobutyrate (Forster and MiJLLER), T,,
195.

2287

27 III— 29 III FORMULA INDEX

C.v-H-^ON.. Brilliant-greeu (earbiuol-fonn), rate of reaction of, with acid and

alkali" (SiDGWicK and Mooue), T., 889 ; P., 123.
C>-Hi,;0'iNo B i s (4 :5-d i m e t li 0 X y-2-y3-ni e t li y 1 am i n o e t h y 1 b e u zy 1 i d e n e) a c e t-

one ( + 4H.P), and its dihydioeliloride (Pyman), T., 1274 ; P., 190.
C2;H440Bp.j Dibromocoprostanone (Doree), T., 649.

27 IV

Co^H.jsOsNBr Bromo-A"-benzoyltetiahydropapaverine (Ptman), T., 1617.
C07HJ9O7NS d- and /-Hyoseyamine <i-camphorsiilphonate (Baiikowcliff
and Tutin), T., 1974 ; P., 257.

Cog Group.

C.isH.ioOo CIS- and <ra;is-s-Dibenzoylstilbene, refraction of (Smedley), T., 220 ;

P., -17.
Co8H.^04 5:8-Diphenoxv-l:2-, -1:3-, and -l:4-dimethylanthraquinone (Har-

ROP, NoRRis, and Weizmann), T., 1315, 1317, 1319.
CisHMOg Apocynamarin ( + 2H2O) (Moore), P., 750 ; P., 85.
C2SH50O4 Diiuentliyl suberate, and its rotatory power (Hilditch), T., 1579;

P., 214.

28 III

C28Hi20gCl4 Tetrachloro-a-naplithafluoran (Harrop, Norris, and Weiz-
mann), T., 286.

CosHooOgNo 2:2'-D i hy d r o X y d i-o-n a p h t h y 1 i d e n e-^j-p henylenediamine
(Sexier and Shepheakd), T., 1955.

C28H20O2S0 5:8-Dipbenylthiol-l:2-, -1:3-, and-l:4-dimethylantliraquinone
(Harrop, Norris, and Weizmann), T., 1316, 1318, 1319.

C28H.«02No 5:8-Dianilino-l:2-, -1:3-, and -l:4-dinu'thy lanthraquinone
(Harrop, Norris, and Weizmann), T., 1315, 1317, 1319.

C28H24O3N4 Benzoylmethyl-^j-aminobenzene diazo-oxide (Morgan and
Alcock), T., 1327.

C-28H2.,02Ng Dibenzoyldimethyl-4:4'-dianiinodiazoaniinobeuzenc (Mor-
gan and Alcock), T., 1326.

C09 Group.

CogH-MO l:l-Dibenzyl-3-beuzylidenephthalan (Shibata), T., 1455; P.,
209.

C29H46O2 Acetylhomoandrosterol (Moore), T., 740; P., 85.
C29H52O4 Dimenthyl azelate, and its rotatory j)o\ver (Hilditch), T., 1579;
P., 214.

29 III

C29H23O5N /3-2;-D i b e n z 0 y 1 o X y-iV-b e n z 0 y l-j3-p b e n y 1 e t h y 1 a m i n e (TuTiN,

Catox, and Hann), T., 2121.

C29H28O2N4 DicarbaniHnodi-;;-tolylmethylenediamine (Senier and
Shepheahd), T., 500.

C2;jH28N4S2 D i t H i o ca T b 0-0- and -^-toluidinodipheuylmethylenediamine
(Senier and Shepheard), T., 499, 500.
Dithiocarbanilinodi-^;-tolylinethyIenediamine (Senier and Shep-
heard), T., 502.

Cn;Jin^0^}f2 Brucine sorbate (-|-liH20), and its rotatory power (Hilditch),
t., 1574 ; P., 214.

C29H3fi06N2 Brucine ^Sy-hexenoate, and its rotatory power (Hilditch^, T.,
1574 ; P., 214.

2288

FORMULA INDEX 29 III 32 III

CxiH-igO.No Brucine ?i-lioxoate (+3II.,0), and its rotatory power (Hii.ditch),

t., '1074 ; P., 214.
Cj ,H4oO.-,N2 B i s(4 : 5-d i in c t h o x y-2-/3-e t li y 1 a m i u o e t Ii y 1 b e n zy 1 i d e n e)a c e 1 0 n e,

and its hydrochloride (Py.man), T., 1747.

29 IV

CogH^O^NjS 5-Benzeneazo-l:3-dipheny 1-5-1) fnzyl-2-tIiioliai!(it uric acid
(Whiteley and Mountain), P., 122.

C30 Group.

C.ioHsuO Audrosterol ( + HaO) (Moouk), T., 739 ; P., 8.').

C30H54O4 Diinentliyl sebacate, and its rotatory power (Hi i.ditcii), T., 1580;
P., 214.

30 III

C3oH280iN4 Benzoylethyl-;y-aininoh(jiizonc diazo-oxide (Moiujax and

Alcouk), T., 1328.
CanHogO.^Nr, Dibenzoyldiethyl-4: 4'-d i a ni i u 0 d i a z o a in i u 0 b e n z e n e (Morgan

and Alcock), T., 1326.
CaoHjgOcN Trihydroxy tri-o-tolyloxy tripropylamiue, and its salts (Boyd

and Knowltox), T., 1806 ; P., 235.
C3oH:i(,07N Trihydroxytri-o-tolyloxy tripropy lamine oxide (Hoyd and

ivNOWLTON), T., 1806.
C30H44O10N0 Substance, from roduction of niyristicinylideneamiiioacetal (Sal-
way), T., 1212.
C3oH470r,As Tricamphorvlarsinic acid, and its silver salt (MouoAN and

Mk-kletiiwait), T., 1476 ; P., 212.
C3oH5oOit(N4 Chit in, (C3(,HgnOi9N4)„, polarimetric method of identifying, and

constitution of (Irvine), T., 564 ; P., 89.

30 IV

C3oHi.sO;jNXlo S:9-Dichloro-7:10-dianilino-l-hydroxy naphthacenequin-
one (Haruop, Norris, and Weizmann), T., 288.

C3oH2904N.)Bp Strychnine o-bromocinnaniate, (and -l-H.,0) (James and
SuDisoRoroH), T., 1539.
Strychnine a-bromo«^/ocinnamatc, (and -i- H.,0) (James and Sudborough),
T , 1538.

C3oH4o03l.,Hg4 Substance, from camphor and K.,IIgl4 (Marsh and Struthers),
f., 1781.

C3oH4503CloSb Tricamphorylstibine chloride (Morgan, Micklethwait,
and WiiiTBY;, P., 302.

C31 Group.

C31H32N4S2 Dithiocarbo-o- and -j9-toluidinod i-i^-tolylmethylenediamine
(Senier and Siiepheard), T., 502, 503.

C32 Group.

C32H52O2 Acetylandrosterol (Moore), T., 739; P., 85.

32 III

C32H4oOfiN2 Brucine rf- and Z-l-methylcyclohexylidene-4-acetate (Perkin,
Pope, and Wallach), T., 1795.

2289

32 III— 38 II FORMULA INDEX

CioHjiOoBr Bromoacetvlaudiosterol (Moore), T., 740; P., 85.

Substance, from extract of Afiocynum audrosacmi/oliuni aud bromine (Moobk),
T., 742.

C33 Group.

CasH^gN Coprosterylcarbazolc (Dori^e), T., 654; P., 88.

33 III

Cg3H4sONo Nitroso-derivative of coprosterylcarbazolc (Dor^e), T., 654 ;
P., 88.

C34 Group.

CjHjiOisN Ilepta-acety lamygdalin, preparation and properties of (Tutin),
T., 665 ; P., 118.
Hepta-acetyl?woamygdalin, and resolution and hydrolysis of (Tutin), T.,
666 ; P., 118.
C34H42O6N2 Phenylhydrazone of apocynaraarin (Moore), T., 751.

C35 Group.

C35H2SO.2N4 Dicarbonaphthylaminodiplienylmethylenediamine (Senier

and Shephearp), T., 497.
CssHsgOgNo Brucine piperate ( + HH„0), and its rotatory power (Hilditch),

t.. 1574 ; P., 214.
CssHigOciNc Brucine o;8-liy dropiperate ( + 4H2O), and its rotatory power

(Hilditch), T., 1574 ; P., 214.
Brucine )37'-hydropiperate ( + 3HoO), aud its rotatory power (Hilditch), T.,

1574 ; P., 214.
C35H4oOfiN2 Brucine piperonylbutyrate ( + 4^H,0), and its rotatory power

(Hilditch), T., 1574 ; P., 214.

C36 Group.

CssHseOfiNo Di-^j-arainobenzoplienone camphorate, and its rotatory power
(HildItch), T., 337.

C37 Group.

C37H36O18 Octa-acetylquerciraeritrin (Perkin), T., 2185 ; P., 291.

37 III

C37H32O2N4 Dicarbonaphthylaminodi-^j-tolylmethylenedi amine (Sen-
ier aud Shepheard), T., 501.

C38 Group.

Cv«H-,,Oio Di-a-anhydrotrimethylbrazilone (Perkin and Robinson), T.,

392.
C..H.f,0i2 Trimethoxy-a-brazanquinhydrone (Perkin and Robinson), T.,

::!96.
C-^^mOz Dehydration product of aj8-dimethylanhydroacetonebenzil

(Gray), T., 2134.

2290

FORMULA INDEX 38 IV— 53 III

38 IV

CjsHrioOaNriAs Dibenzoyl derivative of base, from arsenions chloride and aniline
(M(»U(;an and ^Iicklethwait), T., 1475.

CsaHayOuSSb^ Triphenylstibiue hydroxysulphate (Mougan, Mu'KLK-
THWAiT, and Whitby), P., 302.

C3;) Group.

CsgHsoO^NaAs Tribenzoylaminotripliuuylarsine o.xide (MoROA.v and
Micklethwait), T., 1475.

C4J Group.

C42HUO10 Di-a-anhydrotrimetliy Ibrazilone diacotate (Peukin and Robin-
son)", T., 392.

42 III
CjoHj.OSio Tribenzvlsilicyl oxide (Maktin and Kipping), T., 307;

P", 2S'.

Cjs Group.

C4,sHr^0i..N4 Dibrucine oxalate ( + 4iH20), and its rotatory power (Hilditch),
T., 1580 ; P., 214.

C49 Group.

C49H5fiO]oN4 Dibrucine malonate ( + 3H.,0), and its rotatory power (Hilditch),
T., 1580 ; P., 214.

C50 Group.

€501170051011^6 Substance, from interaction of camphor and mercuric and potass-
ium iodides (Maksh and Struthers), T., 1787.

C51 Group.

CsiHfioOioN^ Dibrucine glutarate (-I-4H20), and its rotatory power (HiL-
uitch), T., 1580; P., 214.

C52 Group.

C59H580ioN4 Dibrucine muconate (-fSHoO), and its rotatory power (Hil-
ditch), T., 1573 ; P., 214.

C50H60O1.1N4 Dibrucine aj8-hydromuconate ( -f 5JHoO), and its rotatory power
(Hilditch), T., 1573 ; P., 214.
Dibrucine j87-h vdronuiconate (-i-SHgO), and its rotatory power (Hilditch),
T., 1573; P.. 214.

CsoHfioOioN^ Dibrucine adipate, and its rotatory power (Hilditch), T., 1573;
P., 214.

C53 Group.

C53HR4O10N4 Dibrucine pimelate (-f4H20), and its rotatory power fHiLDixcn),
T., 1580; P., 214.

2291

54 III— 58 III FORMULA INDEX

Co4 Group.

C54H6fi02oN4 Dibruciiio suberate ( + 4iHoO), and its rotatory power (HiL-
DircH), T., 1580 ; P., 214.

C55 Group.

Cr,5H,.j<0inN4 Dibrucine azelate ( + 3II.,0), ami its rotatory power (Hilditch),
T., I08O; P., 214.

C50 Group.

C56H70O10N4 Dibrucine sebacate, and its rotatory power (Hilditch), T.,
1580'; P., 214.

Css Group.

C58H6'>0]oN4 Dibrucine cinnamylidenemalonate ( + 5H2O), and its rotatory
power (Hilditch), T., 1574 ; P., 214.

C58H640).jN4 Dibrucine phenylpropylidenemalonate ( + 3H2O) (Hil-
ditch), T., 1575 ; P., 214.
Dibrucine phenylpropenylnialonate ( + 4H.,0), and its rotatory power
(Hilditch), T., 1574 ; P., 214.

ERRATA.

Vol. XCV (Trans., 1909).

in formula /or " CQ-CgHg " read " CO-CHa."
for "C = 65'95 " read " 0 = 66 "95."

„ "Yfor H"m«Z "Y for OH."

,, " 579 " read "594."

,, "574" „ "594."

,, "o-, /3-," read "a;3-."

,, "OHHg-OEt"rea^ "OH-Hg-Et."

delete ' ' in. "

col. 7 insert " -."

22 col. 6 for " " read " ."

for "Six grams " read "2"16 grams."

' ,, "20" read "40."

25°
i7isert " Density of methyl iodide at —^ = 2 "24603.

for "50-8072" read "41-4518."
,, " phototropic " rcaf^ "thermo tropic."
omit " -3-carboxylic acid."

/CH(CN)-CME^
alter formula to " CMeEt<f );CMe.'

\CH ^n:- C(OH)/
for "acid " read "ester."
,, " hydroxy -acid " 7-ead "dihydrophenol."

* From bottom.

2292

Page

Line

116

14

121

15

427

7

690

3*

711

6

721

6

722

4*

723

11

732

1

732

22

864

6*

1354

2*

1938

12

1938

20

1951

5

1957

24

1957

25

1958

13

1960

7*

.1;

QD

1

C6

Chemical Society, London
Journal

v.95
pt.2
cop, 3

,^fOf

-^PpJied Sd.
Seriaii

PLEASE DO NOT REMOVE
CARDS OR SLIPS FROM THIS POCKET

UNIVERSITY OF TORONTO LIBRARY

STORA'

Cai^

.a. ■frr .-fc.-^