Production of Colouring Matters.
Year: 1897

page_text: Production of Colouring Matters.
We, IVAN LEVINSTEIN and LEVINSTEIN LIMITED, both of Minshull Street, Man-
chester, in the County of Lancaster, Chemical Manufacturers, do hereby declare
the nature of this invention to be as follows:-
-
In the Provisional Specification left by us with our application for Letters
Patent No. 18376 dated the 7th day of August A.D. 1897, we have described that if
para-nitrotoluene sulphonic acid is treated, under certain conditions, with sodium
hypochlorite, it is converted into a new and very valuable product.
It has now been discovered that if this new product is, under certain conditions,
carefully oxidised, as for instance with potassium permanganate in a neutral solu-
tion, a new compound results which shews all the properties of an aromatic
aldehyde.
I. It decolorises potassium permanganate solution in the cold.
II. It reduces Fehling's solution hot and also ammoniacal silver solution but
without producing the mirror.
III. By adding phenyl hydrazine in acetic acid solution to the product of oxida-
tion, a flocculent brownish-red precipitate results which is at present considered
to be the hydrazone of the aldehyde.
IV. If the new product is condensed with tertiary and secondary aromatic
amines, sulphonic acids of leuco bases result which, when oxidised (for instance
with lead peroxide), give very valuable blue-green colouring matters of the
triphenyl methane series.
The new product produced according to this invention is intended to be used for
the production of colouring matters.
We, IVAN LEVINSTEIN and LEVINSTEIN LIMITED, both of Minshull Street, Man-
chester, in the County of Lancaster, Chemical Manufacturers, 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:
In the Specification left by us. with our application for Letters Patent No. 18376

page_text: dated the 7th August A.D. 1897, we have described that, if paranitrotoluene
sulphonic acid is suitably treated with sodium hypochlorite, it is oxidised to
paradinitrostilbene disulphonic acid.
It has now been discovered that if this paradinitrostilbene disulphonic aoid or
its salts be further suitably oxidised, preferably with potassium permanganate,
in a cold neutral solution, a new compound results which shews all the properties
of an aromatic aldehyde. Further investigations have shewn that this new product
has the constitution of a paranitrobenzaldehyde orthosulphonic acid. The follow-
ing are some of the characteristics of our new substance.
I. It decolorises potassium permanganate solution slowly in the cold, easily in
the hot state.
II. It combines with phenylhydrazine in acetic acid solution, forming a reddish-
brown flocculent precipitate of the hydrazone.
III. It unites with hydrazine and semicarbazide in strong solutions of sodium
acetate, forming a yellow crystalline precipitato
IV. It condenses with alkylated aromatic amines and their sulphonic acids,
producing sulphonic acids of leuco bases which, when suitably oxidised, for instance
with lead peroxide, give very valuable blue-green colouring matters of the
triphenylmethane series.
EXAMPLE I.
Production of paranitrobenzaldehyde orthosulphonic acid by oxidation of
dinitrostilbene disulphonic acid.
120 kilos. of pure sodium dinitrostilbene disulphonate or the equivalent quantity
of a less pure sample, is dissolved in about 250 litres of water and, whilst the
temperature is kept low (preferably about 5° to 10° C.), and the solution is being
vigorously stirred, a solution of 50 kilos. of potassium permanganate is allowed to
flow in slowly. The permanganate is immediately decolorised and, when all of it
has been added, the liquid is boiled and filtered off from the 'manganese di-oxitle
which separates out. The colourless filtrate may then be neutralised with acid and
evaporated to dryness. The paranitrobenzaldehyde orthosulphonate of sodium
thus obtained is a slightly yellow coloured crystalline powder which is extremely
soluble in water. For most technical purposes however it is unnecessary to isolate
the nitrobenzaldehyde sulphonic acid, as the liquid which is separated from the
manganese dioxide may be used and directly condensed with alkylated aromatic
aminės.
Production of colouring matters.
EXAMPLE II.
5.0 kilos of the sodium paranitrobenzaldehyde orthosulphonate or a corresponding
quantity of a less pure sample, is dissolved in about ten times its weight of water
and 115 kilos. of ethylbenzylaniline sulphonic acid is added to it, the mass is then
slightly acidified with sulphuric or any other suitable acid, and heated for about 12
hours in an apparatus fitted with a reflux condenser. When the condensation is finish-
ed, the mixture is diluted with several times its volume of water, a sufficient amount
of sulphuric acid is added and the leuco base, which remains in solution, is oxidised
with the theoretical quantity of lead peroxide. in the well known manner.
lead sulphate thus formed is filtered off, the filtrate made alkaline preferably with
ammonia, and the filtrate is evaporated until the colouring matter separates out.
This is then filtered off, pressed and dried. The dry product is a blueish-green
powder with a coppery lustre. It dissolves easily in water and dyes animal fibres
in an acid bath, a pure blueish-green colour which is distinguished by its fastness
to alkalies.
The
We do not limit ourselves to the above given example, as, instead of ethylbenzyl-
aniline sulphonic acid, other suitable alkylated aromatic amines, as for example
dimethylaniline diethylaniline monomethylaniline monomethyl- or monoethyl-
orthotoluidine and the like may be condensed with our new aromatic aldehyde and

page_text: thus a whole series of very valuable blue to blueish-green colouring matters of the
triphenylmethane series may be produced.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:―
1. The process for the manufacture or production of paranitrobenzaldehyde
orthosulphonic acid and its salts by the oxidation of paradinitrostilbene disulphonic
acid or its salts by means of suitable oxidising agents such for example as potassium
permanganate.
2. The process for the manufacture or production of blue to green triphenylme-
thane colouring matters which consists in (a), condensing paranitrobenzaldehyde
orthosulphonic acid or its salts with alkylated aromatic amines or their sulphonic
acids to leuco bases and (b), oxidising the leuco bases thus obtained with suitable
oxidising agents, preferably with lead peroxide, to triphenylmethane colouring
matters, substantially as herein before described.
3. As new articles of manufacture, the hercinbefore described new paranitro-
benzaldehyde orthosulphonic acid and its salts.
4. As new articles of manufacture, the new triphenylmethane colouring matters
produced from paranitrobenzaldehyde sulphonic acid by the process set forth in
the second claiming clause.
W. E. HEYS & SON,
Agents for the Applicants.