Improvements in the Manufacture of Artificial Indigo-white, and of Bodies related to the Indigo-group.
Year: 1894

page_text: Date of Application, 10th May, 1894
Complete Specification Left, 11th Feb., 1895-Accepted, 16th Mar., 1895
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Artificial Indigo-white, and
of Bodies related to the Indigo-group.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of London,
Gentleman do hereby declare the nature of this invention (which has been com-
municated to me by The Badische Anilin and Soda Fabrik of Ludwigshafen-on-
Rhine in the Empire of Germany) to be as follows:-
This invention relates to modifications in the processes for obtaining artificial
indigo-white and indigo described in the Specification of Letters Patent No. 10509
of 1890 granted to me on a communication from my foreign correspondents.
In the said Specification the production of a new material is described. This is
obtained by suitably treating phenyl-glycocoll-ortho-carboxylic acid with alkalies,
or alkaline earths, and is termed artificial indigo-white. It consists of an intimate
combination, or mixture, with unaltered alkali, or alkaline earth, used, of a body
having the nature of a leuco compound and of other products of the reaction.
By their further experiments and researches my foreign correspondents have
recognized that the body, having the nature of a leuco compound, is, as a rule,
a mixture of indoxyl and indoxylic acid and the present invention includes
modifications in the method of operating whereby it is possible to obtain an
artificial indigo-white containing either indoxyl alone, or indoxylic acid alone, as
may be desired.
The special forms of the artificial indigo-white thus obtained can be converted
into indigo by oxidation just as can the product usually obtained when proceeding
as described in the Specification of the said Letters Patent No. 105090.
By operating according to this invention it is possible to isolate indoxyl and
indoxylic acid as is hereinafter further described so that the said invention
provides a technical process for obtaining these bodies which have not hitherto
been prepared commercially.
I. PRODUCTION OF AN ARTIFICIAL INDIGO-WHITE CONTAINING INDOXYLIC
ACID AND LITTLE, OR NO INDOXYL.
In order to produce this form of artificial indigo-white the elimination of water
is conducted with caustic soda and the temperature is allowed to rise to about two
hundred and sixty-five degrees Centigrade. The following example will serve
to illustrate this, but it is capable of considerable variation without departing
from the nature of the invention.
Throughout this Specification the parts are by weight.
EXAMPLE 1.
Mix about 10 parts of sodium phenyl-glycocoll-ortho-carboxylate, which must
be quite neutral and thoroughly dried, with about twenty parts of caustic soda
which must also be as free from water as possible. Grind these two ingredients
together so that they become thoroughly mixed and spread the fine powder so
obtained in a thin layer then heat uniformly to a temperature of about two
bundred and sixty-five degrees Centigrade. Throughout the operation atmo-

page_text: EXAMPLE 3.
Dissolve about 50 parts of the artificial indigo-white obtained as described in 3
Example 1 and ground to powder, in a mixture of about four hundred parts of
ice, and about one hundred and seventy five parts of dilute sulphuric acid,
containing about twenty two per cent. real acid (H,SO).
The indoxylic acid separates out as a white precipitate, filter and wash with
ice-cold water.
In the moist state the acid is very unstable but becomes more stable after
drying. Drying must be effected quickly in the cold, and, as far as possible, in
the absence of oxroen
3

page_text: with ether, free from air, and distil off the ether in the absence of oxygen. The
indoxyl is then obtained as a thick oil.
Indoxyl and indoxylic acid can also be isolated from artificial indigo-white
containing a mixture of these bodies by first isolating the indoxyl as described in
Example 4 and then isolating the indoxylic acid as described in Example 3.
Deted the 10th day of May 1894
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, Agents.
Improvements in the Manufacture of Artificial Indigo-white, and
of Bodies related to the Indigo-group.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields, in the County of London,
Gentleman, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by The Badische Anilin and Soda Fabrik, of
Ludwigshafen-on-Rhine, in the Empire of Germany) and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement:―
This invention relates to modifications in the processes for obtaining artificial
indigo-white and indigo described in the Specification of Letters Patent No. 10509
of 1890 granted to me on a communication from my foreign correspondents.
In the said Specification the production of a new material is described. This is
obtained by suitably treating phenyl-glycocoll-ortho-carboxylic acid with alkalies
or alkaline earths and is termed artificial indigo-white. It consists of an intimate
combination or mixture with unaltered alkali or alkaline earth used, of a body
having the nature of a leuco-compound and of other products of the reaction.
By their further experiments and researches my foreign correspondents have
recognized that the body having the nature of a leuco-compound is as a rule
a mixture of indoxyl and indoxylic acid and the present invention includes modifi-
cations in the method of operating whereby it is possible to obtain an artificial
indigo-white containing either indoxyl alone or indoxylic acid alone as may be
desired.
The special forms of the artificial indigo-white thus obtained can be converted
into indigo by oxidation just as can the product usually obtained when proceeding
as described in the Specification of the said Letters Patent No. 1050990.
By operating according to this invention it is possible to isolate indoxyl and
indoxylic acid as is hereinafter further described, so that the said invention provides
a technical process for obtaining these bodies which have not hitherto been prepared
commercially.
I. PRODUCTION OF AN ARTIFICIAL INDIGO-WHITE CONTAINING INDOXYLIC
ACID AND LITTLE, OR NO, INDOXYL.
In order to produce this form of artificial indigo-white, the elimination of water
is effected by treating phenyl-glycocoll-ortho-carboxylic acid or its sodium salt
with caustic soda and the temperature is allowed to rise to about two hundred and
sixty five degrees Centigrade. The following example will serve to illustrate this,
but it is capable of considerable variation without departing from the nature of the
invention.
Throughout this Specification the parts are by weight.

page_text: Mix together about ten parts of dried neutral potassium phenyl-glycocoll-ortho-
carboxylate with about twenty parts of caustic potash freed from water and heat the
mixture uniformly at about 280 to 290 degrees Centigrade for about one hour.
This operation must also be conducted whilst atmospheric air is excluded or in the
presence of an indifferent gas.
If in the above example a lower temperature be adopted (say about 250 degrees
Centigrade) the artificial indigo-white obtained will contain a mixture of indoxyl
and indoxylic acid, combined of course with the alkali but the treatment at this
lower temperature is not claimed under the present Application.
Grind to powder about 0 parts of the artificial indigo-white obtained as described
in Example and dissolve in a mixture of about four hundred parts of ice, and
about one hundred and seventy five parts of dilute sulphuric acid containing about
twenty two per cent. real'acid (H₂SO,).
The indoxylic acid separates out as a white precipitate. Filter and wash-with
ice-cold water.
In the moist state the acid is unstable but becomes stable after drying. Drying 4
must be effected at a moderate heat (not above fifty degrees Centigrade) by
spreading the material over a large surface. It is advantageous but not necessary
to exclude the oxygen of the atmosphere.

page_text: MXAMITE 1.
Dissolve one part of the artificial indigo-white obtained according to Example 2
in about two to three parts of water free from air, cooling well during the operation.
Saturate the solution obtained with carbonic acid. Next extract with ether, free
from air, and preferably after drying the ether-solution with calcium chloride,.
distil off the ether in the absence of oxygen. The indoxyl is then obtained as a
thick oil.
Indoxyl and indoxylic acid can also be isolated from artificial indigo-white
containing a mixture of these bodies by first isolating the indoxyl as described in
Example 4 and then isolating the indoxylic acid as described in Example 3.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1. The manufacture of an artificial indigo-white containing indoxylic acid and
little or no indoxyl by treating phenyl-glycocoll-ortho-carboxylic acid or its sodium
salt with caustic soda in the manner and under the conditions herein set forth.
2. The manufacture of an artificial indigo-white containing indoxyl and little or
no indoxylic acid by treating phenyl-glycocoll-ortho-carboxylic acid or its potash
salt with caustic potash in the manner and under the conditions hereinbefore set
forth.
3. The manufacture of indoxylic acid by first preparing an artificial indigo-white
containing a large proportion of indoxylic acid then treating this with cold dilute
mineral acid, and separating the precipitated indoxylic acid by filtration all
substantially as hereinbefore described.
4. The manufacture of indoxyl by first preparing an artificial indigo-white-
containing a large proportion of indoxyl then dissolving this in cold water free from
air, and saturating the solution with carbonic acid, next extracting the solution
with ether or the like and distilling off the ether in the absence of oxygen.
Dated this 11th day of February 1895.
JOHNSONS & WILLCOX,
Agents.