Process for Producing Ethereal Salts of Indoxylcarboxylic Acid.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
A Process for Producing Ethereal Salts of Indoxylcarboxylic Acid.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, Chancery
Lane, in the County of London, Chartered Patent Agent, do hereby declare the
nature of this invention (as communicated to me from abroad by The Farbwerke
vormals:-Meister Lucius and Brüning of Hoechst a/ Main, in the Empire of
Germany, Chemical Manufacturers) to be as follows:-
It is known, that by the reaction of metallic sodium upon a mixture of benzoic
acid ether and acetic ether, alcohol is eliminated and the sodium compound is
formed of a ketonic acid ether, viz. of the acetic benzoyl-ether, from which
diluted acids separate the acetic benzoyl-ether.
My foreign correspondents have found that a similar inter-molecular formation
takes place if metallic sodium be allowed to act upon the ethereal salt of phenyl-
glycine-o-carboxylic acid.
The reaction takes place according to the following equation :
Diluted acids separate from this sodium compound the free ethereal salt of a
ketoric acid which my correspondents have found to be identical with the ethereal
salt of indoxylcarboxylic acid.
The process may be carried on in the following manner:-
To a solution of 25 parts by weight of diethyl salt of phenyl-glycine-o-carboxylic
acid (melting point 72° to 73° C.) in 100 parts by weight of boiling benzene, are
introduced 25 parts by weight of granulated sodium (or in another form finely
ground) and in order to start the reaction a few drops of alcohol are added.
Immediately a development of hydrogen begins which increases when the mixture
is gently heated. On the separation of the sodium compound of the ethyl sult of
the indoxyl-carboxylic acid thus formed the liquid slowly solidifies to a white paste.

page_text: When all the sodium has disappeared the product of the reaction is shaken with a
dilute acid, the layer of benzene is removed and the benzene is distilled off.
There now remains an oil which quickly solidifies in the form of crystals. After
one recrystallisation from hot alcohol the substance is quite pure and identical,
when compared, with the ethereal salt of indoxyl-acid, obtained by A. Baeyer
(Ber. XIV. 1744) by the reduction of o-nitrophenyl-propiolic acid.
The reaction takes place in the same manner if for the sodium used in the above
example there be substituted the equivalent quantity of a sodium-alcoholate.
The course of the reaction remains the same; only, instead of the hydrogen atom
formed in the above example, 1 molecule of alcohol is formed.
The ethereal salts of the indoxylcarboxylic acid are used in manufacturing
indigo after the well known process of A. Baeyer.
Dated this 27th day of April 1898.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
A Process for Producing Ethereal Salts of Indoxylcarboxylic Acid.
I, OLIVER IMRAY, of Birkbeck Bank Chambers, Southampton Buildings, Chancery
Lane, in the County of London, Chartered Patent Agent, do hereby declare the
nature of this invention (as communicated to me from abroad by The Farbwerke
vormals:-Meister Lucius aud Brüning, of Hoechst a/Main, in the Empire of Ger-
many, Chemical Manufacturers) and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement :-
It is known that by the reaction of metallic sodium upon a mixture of ethyl
benzoate and ethyl acetate, alcohol is eliminated and the sodium compound of the
ethereal salt of a ketonic acid is formed viz. of ethyl benzoylacetate, from which
diluted acids separate the ethyl benzoylacetate.
My foreign correspondents have found that a similar inter-molecular formation
takes place if metallic sodium be allowed to act upon the ethereal salt of phenyl-
glycine-ortho-carboxylic acid.
The reaction takes place according to the following equation :-

page_text: Diluted acids separate from this sodium compound the free ethereal salt of a
ketonic acid which my correspondents have found to be identical with the ethereal
salt of indoxylcarboxylic acid.
The process may be carried out in the following manner:
To a solution of 25 parts by weight of the diethyl salt of phenyl-glycine-ortho-
carboxylic acid (melting point 72° to 73° C.) in 100 parts by weight of boiling
benzene, are introduced 2-5 parts of weight of granulated sodium (or in another
form finely ground) and in order to start the reaction a few drops of alcohol are
added. Iminediately a development of hydrogen begins which increases when the
mixture is gently heated.
On the separation of the sodium compound of the ethyl salt of the indoxyl-
carboxylic acid thus formed the liquid slowly solidifies to a white paste.
When all the sodium has disappeared the product of the reaction is shaken with
a dilute acid, the layer of benzene is removed and the benzene is distilled off.
There now remains an oil which quickly solidifies in the form of crystals. After
one recrystallisation from hot alcohol the substance is quite pure and identical with
the ethereal salt of indoxyl-carboxylic acid, obtained by A. Baeyer (Ber. XIV 1744)
by the reduction of o-nitrophenyl-propiolic acid.
The reaction takes place in the samo manner if for the ethyl salt of the phenyl-
glycine-ortho-carboxylic acid be substituted the equivalent quantity of another ester
of the same acid, for instance methyl ester.
As is the case with the manufacture of acetyl acetic acid ester, benzoyl acetic
acid ester &c., in this process for the metallic sodium may be substituted the equiva-
lent quantity of a sodium alcoholate.
The course of the reaction remains the same, only, instead of the hydrogen atom
formed in the above example, 1 molecule of alcohol is formed.
The ethereal salts of the indoxylcarboxylic acid are used in manufacturing indigo
after the well known process of A. Baeyer.
Having now. particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I
claim is :-
Process for producing ethereal salts of indoxyl-carboxylic acid consisting in
treating an ethereal salt of phenyl-glycine-orthocarboxylic acid with metallic sodium
or a sodium alcoholate, substantially as described.
Dated this 26th day of January 1899.
ABEL & IMRAY,
Agents for the Applicant.