Improvements in the Manufacture and Production of Indigo-leuco Compounds and other Indigo Products.
Year: 1899

page_text: Date of Application, 20th Nov., 1899
Complete Specification Left, 17th Sept., 1900-Accepted, 20th Nov., 1900
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture and Production of Indigo-leuco
Compounds and other Indigo Products.
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
communicated to me from abroad by the Badische Anilin & Soda Fabrik of
Ludwigshafen-on-Rhine, in the German Empire) to be as follows:-
My foreign correspondents have discovered that the acyl derivatives obtained
by combination of the dialkyl esters of phenyl-glycocoll ortho carboxylic acid
with acetyl are most readily converted into indoxyl compounds (which can easily
be oxidised to indigo) by heating (or by allowing to stand at ordinary tempera-
ture) with the alkaline earths metallic sodium the alkaline alcoholates, ammonia,
hot carbonate of soda solution, and sulphuric acids of various concentrations.
The result of the treatment is the production of indoxyl, or indoxylic acid, or
when alcoholates are used in the presence of alcohol, or benzene, indoxylic acid
ester is obtained. If concentrated sulphuric acid be used the indoxyl compound
obtained becomes sulphonated and oxydised so that indigo-sulpho-acids are
obtained.
Dated this 23rd day of Anoust 1900.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C.,
Agents.
Improvements in the Manufacture and Production of Indigo-leuco
Compounds and other Indigo Products.
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
communicated to me from abroad by the Badische Anilin & Soda Fabrik of
Ludwigshafen-on-Rhine, in the German Empire) and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement:-
-
My foreign correspondents have discovered that the acyl derivatives obtained
by combination of the dialkyl esters of phenyl-glycocoll-ortho-carboxylic acid
with acetyl are most readily converted into indoxyl compounds (which can easily
be oxidised to indigo) by treating the said acyl derivatives with the alkaline
earths (magnesia excepted) metallic sodium, the alkaline alcoholates, ammonia,

page_text: hot carbonate of soda solution, and sulphuric acid of various concentrations.
The result of this treatment is the production of indoxyl or indoxylic acid, or
when alcoholates are used in the presence of alcohol or benzene, indoxylic acid
ester is obtained. If concentrated sulphuric acid be used, the indoxyl compound
cbtained becomes sulphonated and oxidised, so that indigo sulpho acids are
obtained.
The following is an example of the way in which the acetyl-phenyl-glycocoll-
ortho-carboxylic acid dialkyl-ester may be made but I make no claim herein to
it, nor to the method of its production, nor to its conversion by means of caustic
alkalis.
:
Heat
Mix together three parts of phenyl-glycocoll ortho-carboxylic acid diethyl-ester,
fifteen parts of acetic anhydride and one part of anhydrous sodium acetate.
the mixture for five hours at its boiling point, then distil off the excess of acetic
anhydride and pour the reaction mass into a dilute solution of soda kept cold by
ice. The acetyl compound separates out as a light brown mass. Purify, if
necessary by dissolving in ether and treating with animal charcoal.
Instead of ethyl ester the equivalent quantity of other esters of the acid, for
instance, the methyl ester can be employed. Instead of acetic anhydride acetyl
chloride can be used for instance at the temperature of the water bath.
The following examples will serve to further illustrate the nature of this
invention and the manner in which it can be practically carried out but it is not
confined to these examples. The parts are by weight.
EXAMPLE 1.
CONVERSION OF THE ACETYL COMPOUNDS INTO INDOXYL AND INDIGO BY MEANS OF
AMMONIA.
Boil together for about half an hour in a vessel fitted with an inverted con-
denser one part of the aforesaid acetyl ester and fifty parts of an ammonia solu-
tion containing about twenty two per cent. NH, and absorb the escaping ammonia
in a receiver. When cold dilute the almost neutral liquid with water, add two
parts of caustic soda solution (containing about twenty per cent. Na OH) and
blow in air. The indigo formed separates out and can be collected in any suit-
able manner.
In place of using ammonia in this example the condensation can be effected by
means of metallic sodium, or sodium ethylate and in the latter case either by
heating with the dry substance or by treating in alcoholic or benzene solution.
EXAMPLE 2.
CONVERSION OF THE ACETYL COMPOUNDS INTO INDOXYL AND INDIGO BY MEANS OF
SODIUM CARBONATE SOLUTION.
Boil for half an hour one part of the aforesaid acetyl ester with five parts of
carbonate of soda solution containing about eight per cent. Na, CO, in a reflux
apparatus or until the whole has gone into solution. Dilute with water, add
two parts of caustic soda solution containing about twenty per cent. Na OH and
blow in air. The indigo formed separates out.
EXAMPLE 3.
CONVERSION OF THE ACETYL COMPOUNDS INTO INDOXYL AND INDIGO BY MEANS OF
BARIUM HYDRATE.
Boil together one part of the aforesaid acetyl ester, five parts of barium
hydrate and fifty parts of water in a vessel provided with a reflux condenser for
about half an hour, or until the acetyl ester has practically disappeared. Blow
air through the hot solution. The indigo formed is precipitated and can be
purified from any admixed barium carbonate by treatment with dilute hydro-
choric acid.

page_text: EXAMPLE 4.
CONVERSION OF THE ACETYL COMPOUNDS INTO INDIGO BY MEANS OF SULPHURIC ACID.
Add one part of the aforesaid acetyl ester to about five parts of sulphuric acid
containing a small quantity, say about four per cent. of free sulphuric anhydride.
Heat the mixture, for a short time, on the water bath, until no increase in the
blue colour formed can be observed. Pour the sulphuric acid solution on to
ice and precipitate the indigo sulphoacid by means of common salt.
Instead of the sulphuric acid prescribed in this example stronger fuming acids
can be employed but the stronger the fuming acid is, the greater must be the care
taken, that the temperature does not rise too high.
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 :-
1. The manufacture of indigo-leuco compounds and indigo therefrom, by treat-
ing the dialkyl esters of acetyl-phenyl-glycocoll-ortho-carboxylic acid with the
alkaline earths (magnesia excepted) ammonia, metallic sodium, the alkaline
alcoholates, carbonate of soda solution or sulphuric acid and oxidising the leuco
bodies obtained, all substantially as herein before described.
2. The manufacture of indigo products by treating the dialkyl esters of acetyl-
phenyl-glycocoll-ortho-carboxylic acid with sulphuric acid substantially as herein-
before described.
3. The manufacture of indigo-leuco compounds by treating the dialkyl esters
of acetyl-phenyl-glycocoll-ortho-carboxylic acid with the alkaline earths (mag-
nesia excepted) ammonia metallic sodium, the alkaline alcoholates, or carbonate
of soda solution, substantially as herein before described.
4. The manufacture of indigo-leuco compounds and indigo products sub-
stantially as described in the foregoing examples.
Dated this 17th day of September 1900.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C.,
Agents.

page_text: Date of Application, 20th Nov., 1899
1900
Complete Specification Left, 17th Sept., 1900-Accepted, 20th Nov.,
PROVISIONAL SPECIFICATION,
Improvements in the Manufacture and Production of Indigo Leuco
Compounds and other Indigo Products, and of Materials for use
therein.
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
communicated to me from abroad by the Badische Anilin & Soda Fabrik, of
Ludwigshafen on Rhine, in the German Empire) to be as follows:-
My foreign correspondents have discovered that the dialkylesters of phenyl-
glycocoll-ortho-carboxylic acid can be readily combined with formyl, carbethoxyl,
or benzoyl.
The new acyl derivatives thus obtained are most readily converted into indoxyl
This conversion can not
compounds which can easily be oxidized to indigo.
only be effected by the action of caustic alkalies but also by heating in dilute
alkaline solution. The reaction even takes place when such alkaline solutions
are allowed to stand at ordinary temperature. Besides the caustic alkalies the
metallic sodium
alkaline alcoholates,
the
ammonia,
alkaline earths,
hot carbonate of soda solution, and sulphuric acids of various concentra-
The result of the treatment is
tions, are capable of effecting the conversion.
the production of indoxyl, or indoxylic, acid, or, when alcoholates are used, in
the presence of alcohol, or benzene, indoxylic acid ester is obtained. If con-
centrated sulphuric acid be used the indoxyl compound obtained becomes sul-
phonated and oxydised so that indigo-sulpho-acids are obtained. The following
examples will serve to further illustrate the nature of the invention, but the
invention is not confined to the examples. The parts are by weight.
EXAMPLE I.
PRODUCTION OF THE FORMYL DERIVATIVE OF PHENYL-GLYCOCOLL-ORTHO-CARBOXYLIC
ACID DIETHYL-ESTER.
Mix together in a closed vessel one part of the said ester and two parts of
Heat the mixture from
formic acid containing 90 per cent. of real acid.
one, to two, hours, at a .temperature of about one hundred and fifty degrees
Centigrade. Allow the mixture to cool, filter, and evaporate in vacuum.
Dissolve the residue in ether, and shake it out with soda solution. Distil off
the ether from the ethereal solution and the desired formyl compound remains.

page_text: ester and twenty parts of benzoyl chloride. Heat the mixture for about half an
hour on the water bath until the evolution of hydrochloric acid has ceased. Distil
off the excess of benzoyl chloride by means of steam, dissolve the residue in
ether, shake out the ethereal solution with soda solution in order to remove the
benzoic acid. Dry the ethereal solution and distil off the ether. The benzoyl-
phenyl-glycocoll-ortho-carboxylic acid di-ethyl ester is thus obtained as a thick
oil which cannot be distilled, even at a very low pressure, without decomposition.
EXAMPLE III.
PRODUCTION OF ETHOXY-CARBOXYL-PHENYL-GLYCOCOLL-ORTHO-CARBOXYLIC ACID
DI-ETHYL ESTER.
Mix together twenty seven parts of phenyl-glycocoll-ortho-carboxylic acid
di-ethyl-ester, and eleven parts of chloroformic acid ethyl ester. Heat the
mixture on the water bath until the development of hydrochloric acid ceases.
The melted mass soon solidifies. Treat this with water and with a cold dilute
solution of carbonate of soda.
The desired acylated ester remains undissolved, in an almost pure condition.
It dissolves most readily in the usual organie solvents, and can be boiled, without
decomposition, at a temperature above three hundred and sixty degrees Centi-
grade.
EXAMPLE IV.
CONVERSION OF THE NEW COMPOUNDS AFORESAID INTO INDOXYL BY MEANS OF
ALKALI.
Mix one part of the ester obtained according to the foregoing Example I,
with ten parts of caustic soda solution containing about 20 per cent. NaOH.
Boil the mixture, for about half an hour, in a vessel provided with an inverted
condenser, preferably excluding air as far as possible. Allow the solution to
cool and precipitate indoxyl from it, unless it is desired to convert it directly
into indigo by oxydation.
If more concentrated caustic soda be taken, (for instance, one containing
about 35 per cent NaOH) the yield of indoxyl is diminished as the esters are
saponified. But, on the other hand, if the said ester be treated with solid caustic
soda, at the temperature of the water bath, favourable results are once more
obtained.
Instead of caustic soda lye, caustic potash solution, milk of lime, or baryta
water, can be used; the reaction proceeds not only on boiling with alkalies but
also if the cold aqueous solutions are allowed to stand for a long time. The con-
densation can also be effected by means of metallic sodium, or sodium ethylate,
and, in the latter case, either by heating with dry substances, or by treating
iu alcoholic, or benzene, solution. Ammonia, or hot soda solutions, can also be
employed in an analogous manner.
Instead of the formyl-ester prescribed in the foregoing example the analogous
products obtained according to the foregoing Examples II, and III can be
similarly employed.
EXAMPLE V.
CONVERSION OF THE AFORESAID COMPOUNDS INTO INDIGO BY MEANS OF SULPHURIC
ACID.
Add one part of the ester, obtained according to the foregoing Example I, to
about five parts of sulphuric acid containing a small quantity, say about
4 per cent., free sulphuric anhydride. Heat the mixture for a short time on
the water bath until no increase in the blue colour formed can be observed.
Pour the sulphuric acid solution on to ice and precipitate the indigo-sulpho-acid
by means of common salt.

page_text: Instead of the sulphuric acid prescribed in this example ordinary concentrated
sulphuric acid (containing about 96 per cent. H₂SO₁) can be employed or
stronger fuming acids can be used; but the stronger the fuming acid is the
greater must be the care taken that the temperature does not rise too high.
Instead of the ester used in this example the compounds of Examples II and III
can be employed.
1
021
1
1000
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C.,.
Agents.
Improvements in the Manufacture and Production of Indigo Leuco
Compounds and other Indigo Products, and of Materials for use
therein.
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
communicated to me from abroad by the Badische Anilin & Soda Fabrik, of
Ludwigshafen-on-Rhine, in the German Empire) and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement:-
-
My foreign correspondents have discovered that the dialkyl-esters of phenyl-
glycocoll-ortho-carboxylic acid can be readily combined with formyl, carbethoxyl
or benzoyl.
The new acyl derivatives thus obtained are most readily converted into indoxyl
This conversion can be
compounds which can be easily oxidised to indigo.
effected not only by the action of caustic alkalies, but also by heating with dilute
alkaline solutions. The reaction even takes place when such alkaline solutions
are allowed to stand at ordinary temperature. Besides the caustic alkalies, the
alkaline earths (magnesia excepted) the alkaline alcoholates, metallic sodium,
ammonia, hot carbonate of soda solution and sulphuric acids of various concentra-
tions are capable of effecting the conversion. The result of the treatment is
the production of indoxyl, or indoxylic acid, or, when alcoholates are used in
the presence of alcohol, or benzene, indoxylic acid, ester is obtained. If con-
centrated sulphuric acid be used, the indoxyl compound becomes sulphonated
and oxvdised so that indigo sulphoacids are obtained.
The following examples will serve to further illustrate the nature of this
invention and the manner in which it can be carried out in practice but it is
not confined to the examples. The parts are by weight.
EXAMPLE 1.
PRODUCTION OF THE FORMYL DERIVATIVE OF PHENYL-GLYCOCOLL-ORTHO-CARBOXYLIC-
ACID-DIETHYL-ESTER.
Mix together in a closed vessel, one part of the said ester and two parts of
formic acid containing ninety per cent. of real acid. Heat the mixture, from
one to two hours, at a temperature of about one hundred and fifty degrees
Centigrade. Allow the mixture to cool, filter, and evaporate in vacuum.
Dissolve the residue in ether, and shake it out with soda solution. Distil off
the ether from the ethereal solution and the desired formyl compound remains,

page_text: The new formyl compound so obtained is very easily soluble in organic solvents
and has but little tendency to crystallise.
Instead of ethyl ester used in the above example the equivalent quantity of
other esters of the phenyl-glycocoll-ortho-carboxylic acid, for example the
dimethyl-ester, can be employed.
EXAMPLE 3.
PRODUCTION OF ETHOXY-CARBOXYL-PHENYL-GLYCOCOLL-ORTHO CABOX LYLIC ACID-
DIETHYL ESTER.
Mix together twenty-seven parts of phenyl-glycocoll-ortho-carboxylic acid-
diethyl-ester and eleven parts chloroformic-ethyl-ester Heat the mixture on the
water bath until the development of hydrochloric acid ceases. The melted mass
soon solidifies. Treat this with water and with a cold dilute solution of carbonate
of soda.
It dis-
The desired ester remains undissolved in an almost pure condition.
solves most readily in the usual organic solvents, and can be boiled without
decomposition at a temperature above three hundred and sixty degrees Centi-
grade.
EXAMPLE 4.
CONVERSION OF THE NEW ACYL COMPOUNDS INTO INDOXYL BY MEANS OF ALKALI.
Mix together one part of the formyl-ester obtained according to the foregoing
Example 1 with ten parts of caustic soda solution containing about twenty per cent.
NaOH. Boil the mixture for about half an hour in a vessel provided with an
inverted condenser preferably excluding the air as far as possible. Allow the
solution to cool and precipitate indoxyl from it, unless it is desired to convert
it directly into indigo by oxidation.
If more concentrated caustic soda be taken (for instance, one containing about
thirty five per cent. NaOH) the yield of indoxyl is diminished as the esters are
saponified. But, on the other hand, if the said ester be treated with solid caustic
soda, at the temperature of the water bath, favorable results are obtained.
Instead of caustic soda lye, caustic potash solution, milk of lime, or baryta
water can be used. The reaction proceeds not only on boiling with alkalies,
but also if the cold aqueous solutions be allowed to stand for a long time. The
condensation can also be effected by means of metallic sodium, or sodium
alcoholate, and, in the latter case, either by heating with the dry substance, or by
treating in alcoholic, or benzene, solution. Ammonia, or hot carbonate of soda
solution can also be employed in an analogous manner.
Instead of the formyl-ester prescribed above the products obtainable according
to the foregoing Examples 2 and 3 can be similarly employed.

page_text: EXAMPLE 3.
CONVERSION OF THE AFORESAID COMPOUNDS INTO INDIGO BY MEANS OF SULPHURIC
ACID.
Add one part of the formyl ester obtained according to the foregoing Example 1
to about five parts of sulphuric acid, containing a small quantity, say four per
cent., free sulphuric anhydride. Heat the mixture for a short time on the water
bath until no increase in the blue colour formed can be observed. Pour the
sulphuric acid solution on to ice and precipitate the indigo sulphoacid by means
of common salt.
Instead of the sulphuric, acid prescribed in this example stronger fuming
acids can be used, but the stronger the fuming acid is, the greater must be the
care taken, that the temperature does not rise too high.
Instead of the formyl ester used above the other compounds hereinbefore named
(and which can be produced according to the foregoing Examples and 3) can
be employed.
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:
1. The manufacture. of materials for use in the production of indigo-leuco
compounds and other indigo products by treating the dialkyl-esters of phenyl-
glycocoll-ortho-carboxylic acid with formic acid, or benzoyl chloride or chloro-
tormic-alkyl-ester, substantially as herein before described.
2. The manufacture of indigo-leuco compounds by treating the bodies such as
can be obtained in accordance with the preceding claiming clause with caustic
alkalies, the alkaline earths (magnesia excepted) ammonia carbonate of soda
solution metallic sodium or alkaline alcoholates, substantially as hereinbefore
described.
3. The manufacture of indigo products by treating the bodies such as can
be obtained in accordance with the preceding first claiming clause with sulphuric
acid substantially as herein before described.
4. The manufacture of indigo-leuco bodies and indigo therefrom by treating the
bodies such as can be obtained in Claiming Clause 1 with caustic alkalies, the
alkaline earths (magnesia excepted) ammonia carbonate of soda solution metallic
sodium, alkaline alcoholates, or sulphuric acid, and oxidising the leuco bodies
obtained substantially as described.
5. The manufacture of indigo-leuco compounds or other indigo products, and
of materials for use therein; substantially as described in the foregoing examples.
6. As new articles of manufacture bodies such as can be obtained in accordance
with the preceding first claiming clause.
Dated this 17th day of September 1900.
JOHNSONS & WILLCOX,
47, Lincoln's Inn Fields, London, W.C.,
Agents.