Improvements in the Manufacture of Indigo Coloring Matters and Intermediate Products
Year: 1898

page_text: Improvements in the Manufacture of Indigo Coloring Matters and
Intermediate Products,
A communication from LA SOCIÉTÉ CHIMIQUE DES USINES DU RHÔNE, ANCIENNE-
MENT GILLIARD, P. MONNET ET CARTIER, of Lyons, France, Manufacturers.
I, GEORGE BELOE ELLIS, of the Firm of J. C. Mewburn & Ellis, of 55
and 56, Chancery Lane, in the County of London, Chartered Patent Agents, do
hereby declare the nature of this invention to be as follows:-
This invention relates to the manufacture of new indigo colouring matters,
having the chemical constitution of methyl indigoes, from meta-toluylic aldehyde,
and to the production in a pure state of the intermediate chemical bodies employed
in the said manufacture.
My correspondents have discovered that when meta-toluylic aldehyde is nitrated,
a mixture of nitro products is obtained, varying in proportion according to the
conditions of nitration, and from this mixture they have isolated two crystalline
mono-nitro toluylic aldehydes which under suitable treatment yield two isomeric
methyl-indigoes constituting the new indigo colouring matters aforesaid.
The nitration of meta-toluylic aldehydes is preferably carried out under the
following conditions in order to obtain the indigo yielding aldehydes, but these
conditions may be varied.
2 kilos. meta-toluylic aldehyde are dissolved in 20 kilos. concentrated sulphuric
acid (98 per cent.) at a temperature of about 40° C., and to this solution is added.
with constant stirring 1.44 kilo. dry nitrate of soda. The temperature is main-
tained at 40°-45° C., and when the reaction is finished the nitrated mixture
is poured upon ice. The oily mixture of nitro-aldehydes is separated by decantation
washed with water, a small quantity of nitro-toluylic acid which is formed removed
by means of carbonate of soda, and the product again well washed with water.
About 2 kilos. crude nitro-aldehyde may thus be obtained.
The crude nitration product is then fractionally distilled in vacuum, and at a
pressure of 2 mm. nearly the whole distils over between 135° and 145° C. The
first two-thirds of the distillate are collected apart, and cooled to 0° C., when a
crystalline mass of a nitro aldehyde is formed and removed from the mother liquor
by filtration at 0° C. When pure this product melts at 64° C. (uncorrected).
The last third of the distillate is treated separately in a similar manner at 0°C.
and furnishes a nitro aldehyde crystallizing in yellow needles which when pure
melt at 43°-44° C. (uncorrected).
The mother liquors from these filtrations may be resubmitted to fractional
distillation until no further crystals are obtained from the fractions even at a
temperature of -10° C. The nitro aldehydes probably contained in the residues
have not hitherto been obtained crystalline.

page_text: The method of separation from the crude nitrated toluylic aldehyde of the two
crystalline nitro products melting respectively at 64° C. and 44° C. is merely given
as typical and may be modified in detail as the proportions of these nitro products
in the crude material may require.
The difference between the two crystalline nitro toluylic aldehydes thus obtained
is further demonstrated by the different compounds they yield with aniline,
hydroxylamine, phenylhydrazine, etc., all of which have been prepared by my corre-
spondents. Moreover on gentle oxidation the nitro aldehyde melting at 64° C.
yields a corresponding acid melting at 2180-220° C. identified with ortho-nitro-
ineta-toluylic acid (CH, 1; COOH 3; NO, 4), whereas the nitro aldehyde melting
at 44° C. yields an unknown acid melting at 135° C., which is probably isomeric
ortho-nitro-meta-toluylic acid (CH, 1; COOH 3; NO, 2).
Both nitro aldehydes combine with acetone under the influence of suitable
condensation agents to form two ketones, which are probably also isomeric. The
same method is employed for the preparation of both these new isomerides, and
is substantially as follows:-
5 parts nitro-toluylic aldehyde are dissolved in an excess (about 8 parts) of
acetone, cooled to 0° C. and there is added with constant agitation a solution
of 1 part caustic soda in 100 parts water. When the operation (which occupies
about 30 minutes) is completed, the mixture is acidified and the excess of acetone
removed by distillation. The ketone remains as an oily mass which becomes
crystalline when purified by crystallization from ether, benzene, alcohol or other
solvent. In either case the yield of ketone is nearly theoretical, that from the
64° aldehyde melting at 78° 79° C. and that from the 44° aldehyde at 104° C.
The two ketones thus obtained combine with bisulphite of sodium, and when
treated with dilute solutions of alkalies are transformed into methyl-indigoes
distinguished by the different indigo hues with which they dye cotton goods.
The transformation of the ketone from 44° aldehyde is however much more
difficult to accomplish than the formation of indigo coloring matter from the
isomeric product.
6 parts ketone melting at 104° C. (from nitro-toluylic aldehyde melting at 44° C.)
is agitated for several hours in 100 parts of 8 per cent. caustic soda solution.
When the operation is finished the precipitated indigo coloring matter is filtered,
washed and dried. It weighs about half the weight of ketone taken, and dyes a
very violet shade.
The methyl indigo from the nitro-toluylic aldehyde melting at 44° C. is
prepared with such facility that it is quite unnecessary to separate the intermediate
ketone, and the manufacture of this indigo coloring matter may be carried out in
one operation as follows:-
5 parts nitro-toluylic aldehyde melting at 64° C. are dissolved in 10 parts
acetone and 125 parts of a 2 per cent. caustic soda solution added and well agitated.
Instead of acetone a watery solution of bisulphite may be used to dissolve the
aldehyde; the solution is then treated with acetone and caustic soda.
precipitated indigo coloring matter is filtered, washed and dried. It dyes light
tints a greenish shade and in heavier tints has a very pronounced copper-like
reflection.
The
Both indigo coloring matters are readily reduced by hydrosulphite of sodium
and may be employed for dyeing purposes analogous to ordinary indigo.
Dated this 5th day of December 1898.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.

page_text: Improvements in the Manufacture of Indigo Coloring Matters and
Intermediate Products.
A communication from LA SOCIÉTÉ CHIMIQUE DES USINES DU RHÔNE, ANCIENNE-
MENT GILLIARD, P. MONNET ET CARTIER, of Lyons, France, Manufacturers.
I, GEORGE BELOE ELLIS, of the Firm of J. C. Mewburn & Ellis, of 55
and 56, Chancery Lane, in the County of London, Chartered Patent Agents, do
hereby declare the 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:
This invention relates to the manufacture of new indigo colouring matters,
having the chemical constitution of methyl indigoes, from meta-toluylic aldehyde,
and to the production in a pure state of the intermediate chemical bodies employed
in the said manufacture.
My correspondents have discovered that when meta-toluylic aldehyde is nitrated,
a mixture of nitro products is obtained, varying in proportion according to the
conditions of nitration, and from its mixture they have isolated two crystalline
mono-nitro-toluylic aldehydes which under suitable treatment yield two isomeric
methyl-indigoes constituting the new indigo coloring matters aforesaid.
The nitration of meta-toluylic aldehyde is preferably carried out under the
following conditions in order to obtain the indigo yielding aldehydes, but these
conditions may be varied.
2 kilos. meta-toluylic aldehyde are dissolved in 20 kilos. concentrated sulphuric
acid (98 per cent.) at a temperature of about 40° C., and to this solution is added
with constant stirring 1.44 kilo. dry nitrate of soda. The temperature is main-
tained at 40°-45° C., and when the reaction is finished the nitrated mixture
is poured upon ice. The oily mixture of nitro-aldehydes is separated by decantation
washed with water, a small quantity of nitro-toluylic acid which is formed by
means of carbonate of soda, and the product again well washed with water.
About kilos. crude nitro-aldehyde may thus be obtained.
The crude nitration product is then fractionally distilled in vacuum, and at a
pressure of 2 mm. nearly the whole distils over between 135° and 145° C. The
first two-thirds of the distillate are collected apart, and cooled to 0° C., when a
crystalline mass of a nitro aldehyde is formed and removed from the mother liquor
by filtration at 0° C. When pure this product melts at 64° C. (uncorrected)."
The last third of the distillate is treated separately in a similar manner at 0° C.
and furnishes a nitro aldehyde crystallising in yellow needles which when pure
melt at 43° 44° C. (uncorrected).
The mother liquors from these filtrations may be resubmitted to fractional
distillation until no further crystals are obtained from the fractions even at a
temperature of 10° C. The nitro aldehydes probably contained in the residues
have not hitherto been obtained crystalline.
The method of separation from the crude nitrated toluylic aldehyde of the two
crystalline nitro products melting respectively at 64° C. and 44° C. is merely given
as typical and may be modified in detail as the proportions of these nitro products
in the crude material may require.
The difference between the two crystalline nitro toluylic aldehydes thus
obtained is further demonstrated by the different crystalline compounds they yield
with aniline, hydroxylamine, phenylhydrazine, or other substituted ammonias, all
of which have been prepared by my correspondents and which also may be used
for the separation of the aldehydes by means of fractional crystallisation of the

page_text: same and subsequent liberation of the aldehyde. Moreover on gentle oxidation
the nitro aldehyde melting at 64° C. yields a corresponding acid melting
at 2180-220°C. identified with ortho-nitro-meta toluylic acid (CH, 1; COOH 3;
NO, 4), whereas the nitro aldehyde melting at 44° C. yields an unknown acid
melting at 135° C., which is probably isomeric ortho-nitro-meta-toluylic acid
(CH, 1 COOH 3; NO, 2).
Both nitro aldehydes combine with acetone under the influence of suitable
condensation agents to form two ketones, which are probably also isomeric. The
same method may be employed for the preparation of both these new isomerides,
and is substantially as follows:-
5 parts nitro-toluylic aldehyde are dissolved in an excess (about 8 parts) of
acetone, cooled to 0°C. and there is added with constant agitation a solution
of 1 parts of caustic soda in 100 parts water. When the operation (which occupies
about 30 minutes) is completed, the mixture is acidified and the excess of acetone
removed by distillation. The ketone remains as an oily mass which becomes
crystalline when purified by crystallisation from ether, benzene, alcohol or other
solvent. In either case the yield of ketone is nearly theoretical, that from the
64° aldehyde melting at 78° 79° C. and that from the 44° aldehyde at 104° C.
The two ketones thus obtained combine with bisulphite of sodium, and when
treated with dilute solutions of alkalies are transformed into methyl-indigoes
distinguished by the different indigo hues with which they dye cotton goods.
The transformation of the ketone from 44° aldehyde is however much more
difficult to accomplish than the formation of indigo coloring matter from the
isomeric product.
6 parts ketone melting at 104° C. (from nitro-toluylic aldehyde melting at 44° C.)
is agitated for several hours in 100 parts of 8 per cent. caustic soda solution.
When the operation is finished the precipitated indigo coloring matter is filtered,
washed and dried. It weighs about half the weight of ketone taken, and dyes a
very violet shade.
The methyl indigo from the nitro-toluylic aldehyde melting at 64° C. is
prepared with such facility that it is quite unnecessary to separate the intermediate
ketone, and the manufacture of this indigo coloring matter may be carried out in
one operation as follows:-
5 parts nitro-toluylic aldehyde melting at 64° C. are dissolved in 10 parts
acetone and 125 parts of a 2 per cent. caustic soda solution added and well agitated.
Instead of acetone a watery solution of bisulphite may be used to dissolve the
aldehyde the solution is then treated with acetone and caustic soda. The
precipitated indigo coloring matter is filtered, washed and dried. It dyes in light
tints a greenish shade and in heavier tints has a very pronounced copper-like
reflection.
Both indigo coloring matters are readily reduced by hydrosulphite of sodium
and may be employed for dyeing purposes analogous to ordinary indigo.
Having now particularly described and ascertained the nature of the said
invention, as communicated to me, and in what manner the same is to be
performed, I declare that what I claim is :-
1. The production of an indigo coloring matter having the constitution of
methyl-indigo obtained by nitrating meta-toluylic aldehyde, separating from the
mixed nitro products the mono-nitro-toluylic aldehyde having a melting point
about 44° C. condensing the latter aldehyde with acetone in the presence of dilute
alkaline agents and converting this condensation product into indigo coloring
matter by treatment with caustic alkalies, substantially as described.
2. As a new product the indigo coloring matter such as would result from the
process claimed in Claim 1.
3. In the production of indigo coloring matters from meta-toluylic aldehyde,
the isolation from the mixed nitro products obtained by nitration of meta-toluylic
aldehyde of two separate crystalline isometric mono-nitro-toluylic aldehydes dis-

page_text: tilling between 135° and 145° C. at 2 m.m. pressure and having melting points
of about 44° C. and 64° C. respectively, substantially as described.
4. The manufacture of an indigo coloring matter having the constitution of
methyl-indigo obtained by nitrating meta-toluylic aldehyde, separating from the
mixed nitro products the mono-nitro-toluylic aldehyde having a melting point of
about 64° C., condensing the latter aldehyde with acetone in the presence of dilute
alkaline agents and converting this condensation product into indigo coloring
matter by treatment with caustic alkalies, substantially as described.
5. As new products in the manufacture of indigo coloring matters the two
isomeric mono-nitro-toluylic aldehydes having the physical characteristics herein
described, and their condensation products with acetone.
Dated this 5th day of September 1899.
J. C. MEWBURN & ELLIS,
55 and 56, Chancery Lane, London, Chartered Patent Agents.