The Manufacture and Production of Artificial Indigo and of a New Material suitable for use therein.
Year: 1890

page_text: Date of Application, 7th July, 1890
Complete Specification Left, 7th Apr., 1891-Accepted, 9th May. 1891
PROVISIONAL SPECIFICATION.
The Manufacture and Production of Artificial Indigo and of a New
Material suitable for use therein.
I JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this invention which has been communi-
cated to me from abroad by The Badische Anilin and Soda Fabrik of Ludwigshafen
on Rhine in the Empire of Germany to be as follows:-
This invention relates to a new synthesis of indigo and is based upon the
observations that (1) by the interaction of molecular proportions of anthranilic acid
and mono-chloracetic acid a new compound phenyl-glycocoll-ortho-carboxylic acid
is produced (2) by melting this product with excess of caustic alkali or heating it
with an alkaline earth a body is produced having the character of a leuko-compound
(3) by oxidizing the last nained compound by means of an oxidizing agent such as
ferric chloride or when in alkaline solution the oxygen of the air artificial indigo
results.
I give the following examples to further illustrate the nature of this invention
without limiting myself to them. The parts are by weight.
FIRST STEP. THE PREPARATION OR PRODUCTION OF PHENYL-GLYCOCOLL-
ORTHO-CARBOXYLIC ACID.
Mix about sixty eight parts of anthranilic acid with about forty seven parts of
mono-chloracetic acid and about five hundred parts of water and boil for about two
hours in a vessel fitted with an inverted or reflux condenser. Allow the resulting
solution to stand until part of the acid produced crystallizes out, separate the
crystals from the mother liquor, hydro-extract and dry. Concentrate the mother
liquor by evaporation and so gain a second crop of crystals and treat them as before.
The acid is thus obtained in a condition sufficiently pure for use in the next stage
of the process, but any desired degree of further purity can be obtained by repeated
crystallization from water. The pure acid is characterized by the following
properties It is slightly soluble in cold water, more readily soluble in hot water
and alcohol by crystallization from water, it is obtained as a yellowish powder
that melts at a temperature of about one hundred and ninety eight degrees Centigrade
but decomposes at the same time. Solutions of the acid and of its salts exhibit a bluish
fluorescence. Acetate of lead produces in the aqueous solutions a white floculent
precipitate.
The next stage of the process towards the production of artificial indigo consists
in heating phenyl-glycocoll-ortho-carboxylic acid (or, a salt thereof) to a tempera-
ture of about two hundred degrees Centigrade or higher with an excess of a caustic
alkali (such as caustic potash) calcium hydrate (slaked lime) or barium hydrate or
an equivalent thereof.
SECOND STEP. THE PREPARATION FROM PHENYL-GLYCOCOLL OTHO-CAR-
BOXYLIC ACID OF A PRODUCT YIELDING ARTIFICIAL INDIGO ON OXIDATION.
Melt together about one part of phenyl-glycocoll-ortho-carboxylic acid (obtained
as above described or in any other way) with about three parts of caustic potash
and about one part of water. Stir well and raise the temperature gradually to
about two hundred degrees Centigrade when the mass will assume a yellowish colour.
Continue heating, raising the temperature gradually until the intensity of the colour
no longer increases when the operation is finished.
The final stage of the process the oxidation of the resulting compound may be
effected without any previous purification or separation.

page_text: THIRD STEP. PRODUCTION OF THE ARTIFICIAL INDIGO.
Dissolve the product obtained as above described with about two hundred parts
of water and pass air through until no more blue precipitate separates out. Filter
wash with water containing a little hydrochloric acid then with pure water and
finally with alcohol and then dry the artificial indigo which remains behind.
Dated this 7th day of July 1890.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, Agents.
COMPLETE SPECIFICATION.
The Manufacture and Production of Artificial Indigo and of a New
Material suitable for use therein.
I, JAMES YATE JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this invention which invention has
been communicated 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 :-
In the Specification of the application for Letters Patent numbered 8726 and
dated the 5th June 1890 there is described the manufacture of artificial indigo by
treating phenyl-glycocoll and analogues thereof, with suitable dehydrating agents
to obtain a new compound or material, which on oxidation yields artificial indigo.
The present invention is based upon the discovery that phenyl-glycocoll-ortho-
carboxylic acid when treated in a similar manner also yields an artificial indigo.
The process for the manufacture of artificial indigo according to this new synthesis
can conveniently be described under three heads.
(I.) PRODUCTION OF PHENYL-GLYCOCOLL-ORTHO-CARBOXYLIC-ACID.
Just as phenyl-glycocoll results from the interaction of aniline and mono
chloraceticacid so phenyl-glycocoll-ortho-carboxylic acid can be obtained from
mono-chloracetic acid and aniline-ortho-carboxylic acid, or as it is usually termed
anthranilic acid, (see Mauthner and Suida, Wiener Monatshefte der Chemie 9, 727).
No claim is made to this manufacture of phenyl-glycocoll-ortho-carboxylic acid,
though as it is not an article of commerce an example of the manner in which it
can be prepared is given.
(II.) PRODUCTION OF A NEW MATERIAL WHICH YIELDS INDIGO ON
OXIDATION.
By treating phenyl-glycocoll-ortho-carboxylic acid with suitable reagents for
abstracting the elements of water from it a body is produced having the nature of
a leuco-compound. This operation can be effected by means of an alkaline melt
as described in the hereinbefore mentioned Specification of the application for
Patent No. 8726 of 1890. The alkali used may be either caustic potash or caustic
soda or mixtures of these alkalies with or without the addition of an oxide or hydrate
of a metal of the alkaline earths. Also these. alkaline earths can be used alone
without admixture of caustic potash or soda. The product of this stage of the
process consists of an intimate combination or mixture of the unaltered alkali or
alkaline earth used, with a body having the nature of a leuco-compound and with
other products of the reaction, this new material is a form of artificial indigo-white,
as defined in the hereinbefore mentioned Specification of the application for Patent
No. 8726 of 1890.

page_text: (III.) PRODUCTION OF THE ARTIFICIAL INDIGO.
This can best be effected by the action of atmospheric air on an aqueous solution
of the artificial indigo-white, but other oxidising agents (such as ferric chloride in
acid solution for example) can also be used.
The following example illustrates the manner in which the invention can be
carried into practical effect. The parts are by weight.
TRODUCTION OF THEN
Mix about twenty five parts of anthranilic acid with about twenty parts of
monochlor acetic acid in a solution of about thirty three parts of calcined soda in
about one thousand parts of water, and boil for several hours in a vessel fitted with
a reflux condenser, acidify and allow the resulting solution to stand until part of
the acid produced crystallises out, separate the crystals from the mother liquor
treat in a hydro extractor and dry.
The acid thus obtained is in a condition sufficiently pure for use for the purposes
of this invention.
THE PREPARATION OF ARTIFICIAL INDIGO-WHITE (WHICH YIELDS ARTIFICIAL
INDIGO ON OXIDATION) FROM PHENYL-GLYCOCOLL-ORTHO-CARBOXYLIC
ACID.
Melt together about one part of phenyl-glycocoll-ortho-carboxylic acid (obtained
as above described or in any other way) with about from two to four parts of caustic
potash excluding the air as far as possible. Stir well and raise the temperature to
about two hundred degrees Centigrade. The mass will then assume an orange
colour. Continue heating, raising the temperature gradually, until the intensity of
this colour no longer increases. At this point the operation is interrupted and the
mixture is allowed to cool rapidly.
If instead of caustic potash, lime (quick or slaked) or baryta be used, a melt is
not obtained, but the mixture is well stirred and heated in the same way and the
THE PREPARATION OF ARTIFICIAL INDIGO-WHITE (WHICH YIELDS ARTIFICIAL
INDIGO ON OXIDATION) FROM PHENYL-GLYCOCOLL-ORTHO-CARBOXYLIC
ACID.
Melt together about one part of phenyl-glycocoll-ortho-carboxylic acid (obtained
as above described or in any other way) with about from two to four parts of caustic
potash excluding the air as far as possible. Stir well and raise the temperature to
about two hundred degrees Centigrade. The mass will then assume an orange
colour. Continue heating, raising the temperature gradually, until the intensity of
this colour no longer increases. At this point the operation is interrupted and the
mixture is allowed to cool rapidly.
If instead of caustic potash, lime (quick or slaked) or baryta be used, a melt is
not obtained, but the mixture is well stirred and heated in the same way and the
procedure is entirely similar.
EXAMPLE 3.
PRODUCTION OF THE ARTIFICIAL INDIGO.
Dissolve the artificial indigo-white obtained from one part of phenyl-glycocoll-
ortho carboxylic-acid (as described in Example 2) in about two hundred parts of
water, filter if necessary avoiding all exposure to the air, then pass air through the
clear solution until no more blue precipitate separates out. Filter, wash with water
containing hydrochloric acid, then with water alone and then with alcohol and dry
the artificial indigo which remains behind.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what I
claim is.
First. The manufacture of artificial indigo from phenyl-glycocoll-ortho-carboxylic-
acid by treating it with a reagent for abstracting water to obtain an artificial
indigo-white and oxidizing this artificial indigo-white to obtain artificial indigo all
substantially as herein before described.
Second. The manufacture of a new artificial indigo white from phenyl-glycocoll-
ortho-carboxylic-acid substantially as herein before described.

page_text: Third. As articles of manufacture the artificial indigo-white and the artificial
indigo obtained from phenyl-glycocoll-ortho-carboxylic acid substantially in the
manners herein before described.
Dated thin h ...
1100
J. H. JOHNSON & Co.,
Agents.