New Process for the Production of Indoxyl Compounds, and of Intermediate Products therefor.
Year: 1898

page_text: Date of Application, 14th Mar., 1898
Complete Specification Left, 13th Dec., 1898-Accepted, 18th Feb., 1899
PROVISIONAL SPECIFICATION.
[Communicated from abroad by THE FARBENFABRIKEN VORMALS FRIEDRICH BAYER &
Co., of Elberfeld, Germany.]
New Process for the Production of Indoxyl Compounds, and of
Intermediate Products therefor.
I, HENRY EDWARD NEWTON, of the Office for Patents, 6, Bream's Buildings,
Chancery Lane, in the County of London, Patent Agent, do hereby declare the nature
of this invention to be as follows:-
According to the researches of Manthner and Suida (see Monatshefte der Chemie,
Vol. 9, p. 728) o-tolylglycine cannot be transformed into phenylglycinorthocarbonio
acid by means of oxydising agents.
My foreign correspondents have now found that the said acid, having the
formula-
(R meaning in this formula an acidyl radicle, such as acetyl, benzoyl, or the like)
are treated with suitable oxidising agents, such as potassium persulphate or the
5 like. In order to illustrate this new process, the following example A is given, the
parts being by weight:―
EXAMPLE A.
To a mixture prepared from 20-7 parts of acetyl-orthotolylglycine and 500 parts
of water which has been heated to 80 degrees Centigrade, 31-6 parts of crystallised
0 potassium permanganate are added at one time, whilst stirring. The mixture is
kept at this temperature until the liquid is found to he no longer coloured.
[Price 8d.1

page_text: Subsequently, the mixture is filtered, and the resulting filtrate is acidulated by
means of sulphuric acid. Thus, the acetyl phenylglycincarbonic acid is precipitated
in the shape of glittering colourless crystals.
In an analogous manner, the other acidyl derivatives of phenylglycinecarbonic
acid can be produced.
When treated with alkalies or acids, these acidyl compounds are transformed
into phenyglycine-carbonic acid.
My foreign correspondents have further found that, on treating the salts of phenyl-
glycineorthocarbonic acid or of the above mentioned acidyl derivatives therefrom,
with acetic anhydride, certain indoxyl derivatives are produced. If these indoxyl
derivatives are saponified, and subsequently treated with oxidising agents, indigo is
obtained.
In order to illustrate this process, the following example B is given. The parts
are by weight.
EXAMPLE B.
1 part of dry and finely pulverised disodium salt of phenylglycineorthocarbonic
acid is quickly stirred into 5 parts of boiling acetic anhydride, and the unchanged
acetic anhydride is distilled off in vacuo. The dry residue thus obtained is dissolved
in 8 parts of a 10 per cent. soda lye, and the resulting clear solution is diluted by
means of 100 parts of water. Subsequently, a current of air is introduced into the
solution, until the separation of indigo is completed. The dyestuff is thus
obtained in a very pure state.
In stead of the salts of phenylglycineorthocarbonic acid, or of the acidyl derivatives
therefrom, the free acids can also be employed in the above Example B.
It may be remarked that, in this case, the reaction is preferably performed in the
presence of sodium acetate, of potassium acetate, or of other salts acting in the same
or a similar manner.
The substitution products of the acids above referred to, can likewise be used, such
as ethers, amides, or those derivatives of the said acids which are substitutes in the
benzene nucleus, such, for instance, as the glycine of orthoamidophtalic acid, having
the formula
Un using the last-nameⱭ compound, pure maigo is not obtained, out a dicarbome
acid thereof.
My foreign correspondents wish it to be understood that they do not intend to
confine themselves to the particulars given in the above specification, as these can
be varied within wide limits, without altering thereby the nature of the present
invention.

page_text: New Process for the Production of Indoxyl Compounds, and of
Intermediate Products therefor.
I, HENRY EDWARD NEWTON, of the Office for Patents, 6, Bream's Buildings,
Chancery Lane, in the County of London, Patent Agent, do hereby declare the
nature of this invention and in what manner the same is to be performed,
lo be particularly described and ascertained in and by the following
statement:
According to the researches of Manthner and Suida (see Monatshefte der Chemie,
Vol. 9, p. 727), ortho-tolylglycine cannot be transformed into phenylglycineortho-
carbonic acid by means of oxydizing agents.
My foreign correspondents have now found that the said acid having the
formula
(R measuring in this formula an acidyl radicle, such as acetyl, benzoyl, or the like),
are treated with suitable oxydizing agents, such as potassium permanganate, or the
like.
In order to illustrate this new process, the following example A is given, the parts
being by weight.
EXAMPLE A.
To a mixture prepared from 20-7 parts of acetyl-ortho tolylglycine and 200 parts
of water, which has been heated to 80 degrees Centigrade, 40 parts of crystallized
potassium permanganate are added whilst stirring." The mixture is kept at this
temperature, until the liquid is found to be no longer colored. Subsequently the
mixture is filtered, and the resulting filtrate is acidulated by means of sulphuric acid.
Thus the acetyl-phenyl-glycin-carbonic acid is precipitated in the shape of glittering
colorless crystals, which melt under decomposition at from 210 to 212 degrees
Centigrade.
In an analogous manner, the other acidyl derivatives of phenylglycine carbonic
acid, such as the benzoyl derivative, or the like, can be produced.
When treated with alkalies or acids, these acidyl compounds are transformed into
phenylglycine ortho carbonic acid.
My foreign correspondents have further found that, on treating the salts of phenyl-

page_text: glycine ortho carbonic acid with acetic anhydride, a new indoxyl derivative viz.,
diacetylindoxyl is produced.
In order to illustrate this process, the following Example B is given. The parts are
by weight.
EXAMPLE B.
1 part of dry and finely pulverized disodium salt of phenylglycine ortho carbonic
acid is quickly stirred into 5 parts of boiling acetic anhydride. When the develop-
ment of carbon dioxide, which takes place during the reaction, has ceased, the acetic
anhydride is distilled off in vacuo, and the residue is washed with cold water. Thus,
a slightly yellowish crystalline mass is obtained, which is the new diacetyl indoxyl.
It can be further purified by recrystallisation from hot alcohol, with the addition of
a small quantity of charcoal.
It crystallizes from hot alcohol in the shape of colorless needles melting at
82 degrees Centigrade. According to analytical researches, the new compound has
most probably the formula :-
It is nearly insoluble in water, but easily soluble in alcohol, ether, and acetone.
The same product is obtained if, instead of a salt of phenylglycine ortho carbonic
acid, a salt of the acetyl derivative therefrom, which is described in foregoing
Example A, is employed. Other acidyl derivatives from phenylglycine ortho car-
bonic acid can also be used.
If, e.g., the benzoyl derivative is employed, diacetyl indoxyl is likewise obtained,
the benzoyl radicle being split off, and replaced by the acetyl group during the re-
action.
Instead of the salts of phenylglycine ortho carbonic acid, or of the acidyl deriva-
tives therefrom, the free acids can also be employed in the above Example B.
It may be remarked that in this case the reaction is to be performed in the presence
of sodium acetate, of potassium acetate, or of other salts acting in the same or a
similar manner.
Instead of the hereinbefore mentioned derivatives of phenylglycine ortho carbonic
acid, other derivatives of this acid can be employed.
In order to illustrate the use of such other derivatives, the following example is
given, the parts being by weight.

page_text: acting with acetic anhydride on the salts of phenylglycine ortho carbonic acid, or its
derivatives, or on a mixture of the said acids, with alkaline acetates, or with salts
acting in the same or in a similar manner; secondly saponifying the diacidyl com-
pounds thus obtained; and finally treating the resulting free indoxyl bodies with
oxydizing agents, substantially as hereinbefore described.
7. As new articles of manufacture, the new compounds hereinbefore defined.