A New Process for the Production of Indigo or its Derivatives, and of Intermediate Products for Use therein.
Year: 1899

page_text: Date of Application, 14th July, 1899
Complete Specification Left, 10th Apr., 1900-Accepted, 12th May, 1900
PROVISIONAL SPECIFICATION,
Communicated from abroad by THE FARBENFABRIKEN
BAYER & Co., of Elberfeld, Germany.
°
vormals FRIEDRICHI
A New Process for the Production of Indigo or its Derivatives, and of
Intermediate Products for Use therein.
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:-
In the Application for Letters Patent No. 16201, filed July 25th 1898 (Com-
plete Specification accepted June 24th 1899), my foreign correspondents described
how, by heating phenylglycineorthocarbonic acid with alcohols in the presence
of dehydrating agents, the neutral esters of the phenylglycineortho-carbonic acid
are obtained.
My foreign correspondents have further mentioned in the said Application for
Letters Patent, that the acetylphenylglycineorthocarbonic acid which results
from the oxidation of acetyl-ortho-tolylglycine, can likewise be used as a base
or starting point in this process.
The further investigations of my foreign correspondents have now shown that,
in the latter case a valuable by-product, viz., the acetylated neutral esters of
the phenylglycine orthocarbonic acid, are produced.
In order to illustrate the method of obtaining this product, the following
example is given, the parts being by weight.
EXAMPLE A.
One part of acetylphenylglycineorthocarbonic acid is mixed with 3 parts
of absolute alcohol, and the resulting mixture, which is kept cool, is saturated
with gaseous hydro-chloric acid. After standing for about 12 hours, one half
of the alcohol is distilled off. The residue resulting is stirred into cold water,
and the oil thus obtained, which soon solidifies, is purified by treating the same
with a dilute sodium carbonate solution. The crystalline mass thus obtained
represents a mixture of the neutral esters of the acetylized and the non-acetylized
phenylglycine-ortho-carbonic acid.
In order to isolate, from this mixture, the acetylized ester, it is dissolved
in ether, and, to the resulting solution, ligroïne is added until a precipitate begins
to separate. The acetylized compound, which is difficultly soluble in ligroïne,
separates, at first, in the shape of cubiform crystals. The crystallization is inter-
rupted by filtration as soon as needle-shaped crystals begin to form. Thus,
the pure acetylized compound is isolated, whilst from the filtrate the nonacety-
lized compound separates in the shape of needles, which can likewise be isolated
by filtration.
The new acetylized ester thus obtained melts at 62 degrees Centigrade.
According to the researches of my foreign correspondents, the neutral esters
of the acetylphenylglycineorthocarbonic acid can also be produced by treating the

page_text: neutral esters of the phenylglycineorthocarbonic acid with acetylizing agents,
such as acetyl chloride, acetic anhydride, or the like. In order to illustrate this
method of proceeding, the following Example B is given, the parts being likewise
by weight.
EXAMPLE B.
A mixture of 25 parts of the diethylester of phenylglycine-orthocarbonic acid,
and 16 parts of acetylchloride, is heated, for about one hour, on a water bath, in
a vessel provided with a reflux condenser. Subsequently, the excess of acetyl-
chloride is distilled off, and the oily residue thus obtained, which soon transforms
into a crystalline mass, is washed with cold water.
On dissolving this mass in ether, and adding ligroïne to the resulting solution.
the above described diethyl-ester of the acetylphenylglycineorthocarbonic acid
is obtained in a pure state.
If, instead of acetyl chloride, acetic anhydride, is employed, as an acetylizing
agent, it is preferable to heat the reaction mixture to the boiling point of the
acetic anhydride.
The process proceeds in an analogous manner, if, instead of the neutral esters
of the acetylphenylglycineorthocarbonic acid, the neutral esters of derivatives of
this acid are to be produced.
My foreign correspondents have further found that the neutral esters of the
acetylphenylglycineorthocarbonic acid are very valuable for the production of
indigo, inasmuch as they yield this dye-stuff in a very profitable manner, if they
are subjected to the action of caustic alkalies, and if the leuco compounds thus
produced are treated with oxydizing agents.
In order to illustrate the use of these acetylized esters for the production of
indigo, the following Example C is given, the parts being by weight.
EXAMPLE C.
A mixture prepared from 10 parts of the pure neutral diethylester of acetyl-
phenylglycineorthocarbonic acid, and 20 parts of dry-powdered caustic potassa,
is heated on a water bath. The mixture assumes a yellow color, and an ener-
getic reaction sets in, which is at an end after a short time, alcohol being evolved.
The resulting mass, when cool, is diluted with water. Thus, a yellowish liquid
is produced, from which a good yield of indigo is obtained on passing atmos-
pheric air through the same.
The reaction is performed in an analogous manner if, instead of the diethylester
other neutral esters of acetylphenylglycineorthocarbonic acid, or derivatives of
these esters, are employed.
My foreign correspondents wish to point out that they do not intend to
confine themselves to the particulars given in the above examples, as these
are merely typical, and can be varied within wide limits, without altering the
nature of the present invention.
Dated this 1ith law of T..1.. 1000
NEWTON & SON,
Agents for the Applicant.
A New Process for the Production of Indigo or its Derivatives, and of
Intermediate Products for Use therein.
I, HENRY EDWARD NEWTON, of the Office for Patents, G, Bream's Buildings,
Chancery Lane, in the County of London, Patent Agent, do hereby declare the

page_text: nature of this invention and in what manner the same is to be performed, to
be particularly described and ascertained in and by the following statement:-
In the Specification to Letters Patent No. 16201, A.D. 1898, my foreign corre-
spondents described how, by treating phenylglycine-ortho-carbonic acid with
alcohols in the presence of dehydrating agents, the neutral esters of the phenyl-
glycine ortho-carbonic acid are obtained.
My foreign correspondents have further mentioned in the said specification,
that the acetyl-phenyl-glycine-ortho-carbonic acid which results from the oxida
tion of acetyl-ortho-tolyl-glycine, can likewise be used as a base or starting point
in this process.
The further investigations of my foreign correspondents have now shown, that
in the latter case, besides the neutral esters of phenylglycine-ortho-carbonic acid;
other valuable products, viz., the acetylated neutral esters of the phenylglycine-
ortho-carbonic acid are produced.
In order to illustrate the method of obtaining these products, the following
example is given, the parts being by weight.
EXAMPLE A.
One part of acetylphenyl-glycine-ortho-carbonic acid is mixed with 3 parts of
absolute alcohol, and the resulting mixture, which is kept cool, is saturated
with gaseous hydrochloric acid. After standing for about 12 hours. one half
of the alcohol is distilled off. The residue is stirred into cold water, and the
oil thus obtained (which soon solidifies) is purified by treating it with a dilute
sodium carbonate solution. The crystalline mass thus obtained represents a
mixture of the neutral esters of the acetylized and the non-acetylized phenyl-
glycine-ortho-carbonic acid.
In order to isolate from this mixture the acetilized ester, it is dissolved in
ether, and, to the resulting solution, ligroine is.added, until a precipitate begins
to separate. The acetylized compound, which is not easily soluble in ligroine,
separates at first in the shape of cubiform crystals. The crystallization is inter-
rupted by filtration as soon as needle-shaped crystals begin to form. Thus, the
pure acetylized compound is isolated, whilst from the filtrate the non-acetylized
compound separates in the shape of needles which can likewise be isolated by
filtration.
The new acetylized ester thus obtained melts at 62 degrees Centigrade.
According to the researches of my foreign correspondents, the neutral esters
of the acetyl-phenyl-glycine-ortho-carbonic acid can also be produced by treating
the neutral esters of the phenylglycine-ortho-carbonic acid, with acetylizing
agents, such as acetyl chloride, acetic anhydride, or the like. In order to illus-
trate this method of proceeding, the following example B is given, the parts being
likewise by weight.
EXAMPLE B.
A mixture of 25 parts of the diethylester of phenylglycine-ortho-carbonic acid,
and 16 parts of acetyl-chloride, is heated for several hours on a water-bath.
in a vessel provided with a reflux condenser. Subsequently the excess of acetyl
chloride is distilled off, and the oily residue thus obtained, which soon transforms
into a crystalline mass, is washed with cold water.
On dissolving this mass in ether, and adding ligroine to the resulting solution,
the above-described diethyl-ester of the acetylphenylglycine-ortho-carbonic acid,
is obtained in a pure state.
If. instead of acetyl chloride, acetic anhydride is employed as an acetylizing
agent, it is preferable to heat the reaction mixture to the boiling point of the
acetic anhydride.
The process proceeds in an analogous manner if, instead of the neutral esters
of the acetylphenylglycine-ortho-carbonic acid, the neutral esters of derivatives
of this acid are to be produced.

page_text: My foreign correspondents have further found, that the neutral esters of the
acetylphenylglycine ortho-carbonic acid are very valuable for the production
of indigo, inasmuch as they yield this dye-stuff to a very profitable extent, if
they are subjected to the action of caustic alkalies, and if the leuco compounds
thus produced are treated with oxydizing agents.
In order to illustrate the use of these acetylized esters for the production
of indigo, the following example C is given, the parts being by weight.
is treated on a water-bath.
EXAMPLE C.
A mixture prepared from 10 parts of the pure neutral diethyl ester of acetyl-
phenyl-glycine-ortho-carbonic acid, and 20 parts of dry powdered caustic potassa,
The mixture assumes a yellow color, and an energetic
reaction sets in, which is at an end after a short time, alcohol being evolved. The
resulting mass, when cool, is diluted with water. Thus, a yellowish liquid is
produced from which a very good yield of indigo is obtained on passing atmos-
pheric air through the same.
The reaction is performed in an analogous manner, if, instead of the diethyl-
ester, other neutral esters of acetyl phenylglycine-ortho-carbonic acid, or deriva-
tives of these esters, are employed.
My foreign correspondents wish to point out that they do not intend to confine
themselves to the particulars given in the above examples, as these are merely
typical, and can be varied within wide limits, without altering the nature of the
present invention.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated to
me from abroad, I declare that what I claim is:
1. The process for the production of the neutral esters of the acetyl-phenyl-
glycine-ortho-carbonic acid, which process consists in isolating the same from the
reaction mass obtained by subjecting acetyl-phenyl-glycine-ortho-carbonic acid,
to the process claimed in Claim 1 of Letters Patent No. 16200 A.D. 1898, sub-
stantially as herein before described.
2. The process for the production of the neutral esters of the acetyl-phenyl-
glycine-ortho-carbonic acid, which process consists in heating the neutral
esters of the phenyl-glycine-ortho-carbonic acid with acetylizing agents, sub-
stantially as herein before described.
3. The process for the production of indigo, which process consists in treating
the neutral esters of the acetyl-phenyl-glycine-ortho-carbonic acid obtainable by
the processes described and claimed in the above Claims 1 and 2, with caustic
alkalies, and oxydizing the resulting leuco-compounds, substantially as herein-
before described.
4. As new articles of manufacture, the neutral esters of the acetyl-phenyl-
glycine-ortho-carbonic acid obtainable by the processes herein before described
and claimed.
NEWTON & SON,
Agents for the Applicant.