Manufacture and Production of a Isatine Anilide and of Indigo and Indigo Red therefrom.
Year: 1899

page_text: Manufacture and Production of a Isatine Anilide and of Indigo and
Indigo Red therefrom.
I, THOMAS RICHARD SHILLITO, of 15, Tooks Court, London, E.C., Engineer and
Patent Agent, do hereby declare the nature of this invention-a communication to
me from abroad by Messieurs John Rudolph Geigy & Co, of Basle, Switzerland-to
be as follows:-
The easy transformation of isonitrosonethenyldiphenylamidine into a derivative of
isatine has led my correspondents to suppose that also other bodies relating to the
former compound might be capable, by forming a closed chain, of being converted
into a isatine anilide, when treated with concentrated sulphuric acid. Especially to
be considered were those two compounds which through conversion of the isonitroso
group, either into the cyanide or into the carboxyamide group could be thought to
be intermediate bodies, according as the action of the sulphuric acid was supposed to
be depriving of water or only a transforming one. With regard to the cyanide, it is
identical with the hydrocyancarbodiphenylimide prepared by Laubenheimer (Berl.
Ber. XIII 2155) in combining hydrocyanic acid with carbodiphenylimide. Lauben-
heimer mentions as a characteristic reaction of this body, that in heating with con-
centrated sulphuric acid it gives a red coloured solution, which by diluting with
water remains clear. If a few drops of this solution be poured into water and some
caustic soda lye added, an intensely blue coloured solution is obtained which colour
gradually fades again.
The surprising conformity in the appearance of the colours in this reaction, with
those which appear by heating isonitrosoaethenyldiphenylamidine with concen-
trated sulphuric acid, diluting with water and neutralising with caustic soda lye,
has led my correspondents to expect the formation of the same product of reaction,
namely, the a isatine anilide. A special examination showed that, at the same time,
a isatine anilide is formed thereby only in very small quantities.
The same is to be said of the carboxyamide of the formula:—
which can be obtained by treating hydrocyancar bodiphenylimide with peroxide of
hydrogen (brilliant yellowish crystals melting at 154° to 155° Centigrade).
But an almost quantitative formation of a isatine anilide can be obtained as my
correspondents have further found, in the following manner :—-
Hydrocyancarbodiphenylimide is treated with a yellow solution of ammonium

page_text: sulphide by which the former combines with one molecule of sulphuretted hydrogen
and forms the thio amide of the formula :-
A. von Baeyer has proved in his fundamental works on indigo that certain
derivatives of isatine, as for instance, isatine chloride, pseudo isatine a oxim, isatine
ether, by moderate reduction, particularly with ammonium sulphide, can be trans-
formed into indigo, with which however always more or less indigo red is formed
(Berl. Ber. XI 1217 XII 456 XVI 2203).
My correspondents have found that the new compound, the a isatine anilide joins the
above named isatine. derivatives, but from the point of view of manufacture, with the
very important difference that the formation of the indigo from this compound takes
place very easily and without any admixture of indigo red. However, such an
admixture of indigo red can be brought on, in any desired proportion, if the
reduction of the a isatine anilide is carried out in the presence of certain
quantities of isatine.
The ammonium sulphide, which A. von Baeyer employed
in so many cases with success, has also proved to be the most suitable reducing
agent and its application has the great advantage of being cheap, as sufficient
sulphuretted hydrogen is obtained in my correspondents' production of a isatine
anilide.
Hydrocyancarbodiphenylimide has been prepared by Laubenheimer in two different
ways, either by boiling thiocarbanilide in alcoholic solution with mecuricyanide for a
long time or by introducing hydrocyanic acid in excess into a freshly, according to
Weith (Berl. Ber. VII 1306), prepared solution of unpolymeric carbodiphenylimide
in benzene.
Both methods are unsuitable in practice, but this process can be easily carried out
in any quantities, and without much danger, if the removal of the sulphur is brought
about by oxides or salts of lead preferably by carbonate of lead in the presence of a
soluble cyanide, as for example potassium cyanide. While the carbonate of lead
deprives the thio carbanilide of sulphuretted hydrogen in forming sulphide of
lead, the nascent
carbonic acid decomposes the potassium cyanide and
the nascent hydrocyanic acid combines instantaneously, with the arising carbo-

page_text: takes place. Finally the mixture is boiled for a short time, then the indigo is
filtered off, washed with alcohol, pressed, and dried. The sulphur it contains can be
removed by treatment with sulphuret of carbon.
V. PRODUCTION OF INDIGO WITH INDIGO RED._
To a warm solution of 5 parts of isatine and 15 parts of a isatine anilide in 60 parts
of alcohol are quickly added 40 parts of the above mentioned solution of ammonium
sulphide. The separation of the mixture of indigo with indigo red takes place in
the same way and the further treatment is that above described. In appearance
the product differs little from the foregoing one. Both form a dark crystalline powder
shewing a slight copper coloured lustre, but their colourings on wool, also the solution
of their sulphonic acids, shew a surprising difference in the shades which, according
to the quantity of isatine employed, differ from greenish blue to reddish violet.
Dated this 28th day of July 1899.
THOMAS R. SHILLITO,
15, Tooks Court, London, E.C.
Manufacture and Production of a-Isatine Anilide and of Indigo and
Indigo Red therefrom.
I, THOMAS RICHARD SHILLITO, of 15, Tooks Court, London, E.C., Engineer and
Patent Agent, do hereby declare the nature of this invention and in what manner
the same is to be performed-a communication to me from abroad by Messieurs
John Rudolph Geigy & Co., of Basle, Switzerland, Colour Manufacturers-to be
particularly described and ascertained in and by the following statement :-
The easy transformation of isonitrosoaethenyldiphenylamidine into a derivative of
isatine has led my correspondents to suppose that also other bodies relating to the
former compound might be capable, by forming a closed chain, of being converted
into an isatine anilide when treated with concentrated sulphuric acid. Especially to
be considered were those two compounds which through conversion of the isonitroso
group either into the cyanide or into the carboxyamide group could be thought to be
intermediate bodies, according as the action of the sulphuric acid was supposed to be
depriving of water or only a transforming one. With regard to the cyanide it is
identical with the hydrocyancarbodiphenylimide prepared by Laubenheimer (Berl.
Ber. XIII 2155) in combining hydrocyanic acid with carbodiphenylimide. Lauben-
heimer mentions as a characteristic reaction of this body that in heating with concen-
trated sulphuric acid it gives a red coloured solution which by diluting with water
remains clear. If a few drops of this solution be poured into water and some caustic
soda lye added, an intensely blue coloured solution is obtained, which colour gradually
fades again.
The surprising conformity in the appearance of the colours in this reaction with
those which appear by heating isonitrosoaethenyldiphenylamidine with concentrated
sulphuric acid, diluting with water and neutralising with caustic soda lye, has led my
correspondents to expect the forination of the same product of reaction, namely, the
a-isatine anilide. A special examination shewed that, at the same time, a-isatine
anilide is formed thereby only in very small quantities.
The same is to be said of the carboxyamide of the formula :-

page_text: 5
which can be obtained by treating hydrocyancarbodiphenylimide with peroxide of
hydrogen (brilliant yellowish crystals melting at 154° to 155° Centigrade).
But an almost quantitative formation of a-isatine anilide can be obtained, as my
correspondents have further found, in the following manner :-
Hydrocyancarbodiphenylimide is treated with a yellow solution of ammonium
sulphide by which the former combines with one molecule of sulphuretted hydrogen
and forms the thioamide of the formula :-
A. von Baeyer has proved in bis fundamental works on indigo that certain
derivatives of the isatine, as for instance, the isatine chloride, the pseudo isatine-u-oxim,
the isatine ether, by moderate reduction particularly with ammonium sulphide, can
be transformed into indigo, with which however always more or less indigo red is
formed (Berl. Ber. XI 1217 XII 456 XVI 2203).
My correspondents have found that the new compound, the a-isatine anilide joins
the above named isatine derivatives, but from the point of view of manufacture, with
the very important difference that the formation of the indigo from their compound
takes place very easily and nearly without any admixture of indigo red. However,
such an admixture of indigo red can be brought on in any desired proportion if the
reduction of the a-isitine anilide is carried out in the presence of certain quantities
of isatine. The ammonium sulphide which A. von Baeyer employed in so many cases
with success, has also proved to be the most suitable reducing agent and its application
has the great advantage of being cheap, as sufficient sulphuretted hydrogen is obtained
in my correspondents' production of a-isatine anilide.
Hydrocyancarbodiphenylimide has been prepared by Laubenheimer in two different
ways, either by boiling thiocarbanilide in alcoholic solution with inercuric cyanide for
a long time or by introducing hydrocyanic acid in excess into a freshly, according
to Weith (Berl. Ber. VII 1306), prepared solution of unpolymeric carbodiphenylimide
in benzene.
Both methods are unsuitable in practice but this process can be easily carried out,
in any quantities and without much danger, if the removal of the sulphur is brought
about by oxides or basic salts of lead, preferably by basic carbonate of lead (white lead)

page_text: in the presence of a soluble cyanide, as for example, potassium or sodium cyanide.
While the basic carbonate of lead deprives the thiocarbanilide of sulphuretted
hydrogen in forming sulphide of lead, the nascent carbonic acid decomposes the
potassium cyanide and the nascent hydrocyanic acid combines instantaneously with
the arising carbodiphenylimide to the hydrocyancarbodiphenylimide. In the place
of the mixture of basic carbonate of lead and potassium or sodium cyanide, basic
cyanides of lead can be employed.
The following examples are given to illustrate the manner in which the invention
can be carried out, the parts being by weight.
I. PRODUCTION OF HYDROCYANCARBODIPHENYLIMIDE,
In a vessel fitted with a stirrer are dissolved 7 parts of potassium cyanide
of 98 per cent. (or the equivalent quantity of sodium cyanide) in 20 parts of water.
To this solution are added 30 parts of basic carbonate of lead (white lead), 21 parts
of thiocarbanilide and 50 parts of alcohol, then while stirring it is slowly heated up
to 60° Centigrade.
After a short time the reaction is finished, which can be seen if
a test filtered off the sulphide of lead and boiled with carbonate of lead does not
blacken it any more.
When cold, the contents of the vessel are diluted with water
and the insoluble mixture of sulphide of lead and hydrocyanide is filtered off. After
pressing and drying, the hydrocyancarbodiphenylimide is separated from the sulphide
of lead by extraction with alcohol or ether.
In this example the alcohol can be omitted but in that case the finely powdered
thiocarbanilide must be well mixed with the white lead and the aqueous solution of
alkali cyanide of about 10 per cent. The transformation already begins at
30° to 40° Centigrade but is not finished until after about two days.
The remaining sulphide of lead is again converted with hydrochloric acid into
chloride of lead and the latter by treatment with sodium carbonate and caustic soda
lye into basic carbonate of lead.
•
II. TRANSFORMATION OF THE HYDROCYANCARBODIPHENYLIMIDE INTO THE THIOAMIDE.
In a closed vessel fitted with a stirrer, 20 parts of finely pulverised hydrocyan-
carbodiphenylimide are mixed by stirring at a temperature of from 25° to 45° Centi-
grade with 50 parts of a yellow solution of ammonium sulphide which has been
prepared by introducing 3 parts of sulphuretted hydrogen into 45 parts of aqueous
ammonia of 21 to 22 per cent. and dissolving 25 parts of pulverised sulphur in the
still colourless solution of ammonium sulphide thus obtained. This yellow solution of
ammonium sulphide can also be made by introducing 5 parts of sulphuretted
hydrogen into 45 parts of aqueous ammonia of 21 to 22 per cent. and allowing the
solution to stand for several days till it has taken a yellow colour. The formation of
the thioamide is finished as soon as a filtered and washed test dissolves completely in
diluted bydrochloric acid, which is the case in one or two days.
The formed
thioamide, a lemon coloured crystalline powder, is then filtered off, washed and dried.
Recrystallised from alcohol it forms thin yellow brilliant prisms melting at 161° to 162°
Centigrade and dissolving in diluted mineral acids; if warmned, also in diluted caustic
soda Iye. The chlorhydrate crystallises in well formed clustered yellowish prisms.
III. PRODUCTION OF α-ISATINE ANILIDE.
:
80 parts of concentrated sulphuric acid are heated up to 90 degrees Centigrade,
then gradually added while stirring, 20 parts of the well dried thioamide prepared
after Example II. Care must be taken, by cooling, that the self heating which happens
after every addition, does not exceed 95° Centigrade. With lively developement of
sulphurous acid the thioamide dissolves, the solution takes at first a deep brown violet
colour, finally it turns to an intensively yellowish red. When all is mixed the
temperature is raised to 105° Centigrade till the developement of the sulphurous acid
ceases. After cooling, the solution is poured into a surplus solution of sodium

page_text: recrystallising out of hot benzene or carbon disulphide it can be separated from the
sulphur which it still contains.
IV. PRODUCTION OF INDIGO.
To a warm solution of 20 parts of a-isatine anilide in 60 parts of alcohol are quickly
added 40 parts of a freshly prepared solution of ammonium sulphide containing
10 per cent. sulphuretted hydrogen. By self warming and temporary colouring of green,
then blue, the immediate separation of indigo in small crystals takes place. Finally
the mixture is boiled for a short time, then the indigo is filtered off, washed with
alcohol, pressed and dried. The sulphur it contains can be removed by treatment
with carbon disulphide.
V. PRODUCTION OF INDIGO WITH INDIGO RED.
To a warm solution of 5 parts of isatine and 15 parts of a-isatine anilide in 60 parts
of alcohol are quickly added 40 parts of the above mentioned solution of ammonium-
sulphide. The separation of the mixture of indigo with indigo red takes place in the
same way and the further treatment is that above described. In appearance the
product differs little from the foregoing one. Both form a dark crystalline powder
shewing a slight copper coloured lustre, but the colouring on wool of their sulphonic
acids, also the solutions of these acids shew a surprising difference in the shades
which, according to the quantity of isatine employed, differ from greenish blue to
reddish violet.
Having now particularly described and ascertained the nature of said invention
and in what manner the same is to be performed, as communicated to me by my
foreign correspondents, I declare that what I claim is :
1. The process for the production of hydrocyancarbodiphenylimide consisting in
the action of basic salts of lead, by preference basic carbonate of lead, upon thio
carbanilide in presence of an alkali cyanide, substantially as described.
2. The process for the production of a thioamide having the formula
by treating the aforesaid hydrocyancarbodiphenylimide with a yellow solution of
ammonium sulphide, substantially as described.
3. The process for the production of alpha isatine anilide by introducing the
thioamide referred to in Claim 2 into hot concentrated sulphuric acid, letting cool
down and pouring it into a solution of sodium carbonate containing sufficient ice,
substantially as described.
4. The process for the production of indigo by reducing the alpha isatiue anilide
above described with ainmonium sulphide.
5. The process for the production of indigo mixed with indigo red by reducing
a-isatine anilide in the presence of isatine with ammonium sulphide.
6. As a new product, the thioamide such as is obtained by the processes referred to
in Claims 1 and 2.
7. As a new product, the alpha isatine anilide such as is produced by the processes
referred to in Claims 1, 2, and 3.
Dated this 10th
0
THOMAS R. SHILLITO,
15, Tooks Court, London, E.C.