Production of a Red Azo Colouring Matter.
Year: 1892

page_text: Date of Application, 23rd July, 1892
Complete Specification Left, 11th Apr., 1893-Accepted, 13th May, 1893
PROVISIONAL SPECIFICATION.
[Communicated from abroad by THE SOCIETY OF CHEMICAL INDUSTRY IN
BASLE, of Basle, Switzerland, Chemical Manufacturers.]
Production of a Red Azo Colouring Matter.
I, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Chartered Patent Agent, do hereby declare the nature of this
invention to be as follows :-
Benzidine can be converted into two different mononitro derivatives either by
nitrification of its diacetyl compound or of its sulphate in a solution of concentrated
sulphuric acid.
The production of these derivatives and of azo colouring matters resulting there-
from, has been described by my foreign correspondents in their French Patent
No. 203468 of 31st January 1890, but of the dyestuffs there mentioned none have
as yet been practically used, because, in the first place, the tetrazo colouring
matters resulting from the mononitrobenzidines compared with those of the benzidine
itself, have insufficient affinity for unmordanted cotton, and secondly, because the
tetrazo colouring matters in question although suitable for dyeing wool, present no
advantage over the ordinary mono-azo colouring matters.
My foreign correspondents have succeeded in producing a very valuable red dye
for wool from the mono-nitro benzidine which is obtained by nitrification of a
sulphuric solution of benzidine with one equivalent of a mixture of nitric acid and
to be considered as
sulphuric acid and which, according to its characteristics,
mono-o-nitro-p-diamido-diphenyl.
azo
On diazotising this base and combining its tetrazo compound first with one
equivalent of salicylic acid and afterwards with one equivalent of alpha-naphthol-
alpha-sulpho-acid of Nevile & Winther, a not easily soluble scarlet red
colouring matter is formed, which dyes wool in an acid bath a scarlet red tint, and
which, on account of its remarkable fastness, is superior to all red azo dyes that are
known to my correspondents.
The order of the combinations cannot be varied, that is to say the diazotised
mononitro-benzidine must be made to act as described first upon the molecule of
salicylic acid and then upon the molecule of alpha-naphthol-alpha sulpho acid
(Nevile & Winther) otherwise an isomeric dye stuff of little value will be
obtained.
EXAMPLE.
3.435 kilos. of mononitrobenzidine are dissolved in 30-35 litres of water and mixed
with 4.5 kilos. of muriatic acid.
The mixture cooled down to 4° C. is added in the course of an hour, to a solution
of 2.1 kilos. of sodium nitrite in 10 litres of water.
The aqueous solution of the diazo compound thus formed, is introduced into a
solution of 2.2 kilos. salicylic acid and 8 kilos. soda salt in 20 litres of water at the
temperature of 0° to -5° C.
When the formation of the intermediate product is completed a solution of
4 kilos. of alpha-naphthol-alpha-sulphonate of soda (Nevile & Winther) is added at
a temperature not above 10° C.
Twelve hours afterwards the temperature is raised to 20° C. and the solution is

page_text: It is a red brown powder not easily soluble in cold water, more readily soluble
in warm water; the aqueous solution is yellow red and dyes wool in an acid bath
a bright scarlet red tint.
Dark red shades are obtained on wool mordanted with chromium salts.
The dyes resist the action of air, soap, fulling, chlorine and sulphurous acid.
Dated this 23rd day of July 1892.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Production of a Red Azo Colouring Matter.
1, OLIVER IMRAY, of No. 28 Southampton Buildings, Chancery Lane, in the
County of London, Chartered Patent Agent, 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 :-
Benzidine can be converted into two different mononitro derivatives either by
nitrification of its diacetyl compound or of its sulphate in a solution of concentrated
sulphuric acid.
The production of these derivatives and of azo colouring matters resulting
therefrom, has been described by my foreign correspondents in their French
Patent No. 203468 of 31st January 1890, but of the dyestuff's there mentioned
none have as yet been practically used, because, in the first place, the tetrazo
colouring matters resulting from the mononitrobenzidines compared with those of
the benzidine itself, have insufficient affinity for unmordanted cotton, and secondly
because the tetrazo colouring matters in question although suitable for dyeing
wool, present no advantage over the ordinary mono azo colouring matters.
My foreign correspondents have succeeded in producing a very valuable red dye
for wool from the mono nitro benzidine which is obtained by nitrification of a
sulphuric solution of benzidine with one equivalent of a mixture of nitric acid and
sulphuric acid, and which, according to its characteristics, is to be considered as
mono-o-nitro-p-diamido-diphenyl.
On diazotising this base and combining its tetrazo compound first with one
equivalent of salicylic acid and afterwards with one equivalent of alpha-naphthol
alpha-sulpho acid of Nevile & Winther, a not easily soluble scarlet red azo colouring
matter is formed, which dyes wool in an acid bath a scarlet red tint, and which, on
account of its remarkable fastness, is superior to all red azo dyes that are known
to my correspondents.
The order of the combinations cannot be varied, that is to say the diazotised
mononitrobenzidine must be made to act as described first upon the molecule of
salicylic acid and then upon the molecule of alpha-naphthol-alpha sulpho acid (Nevile
& Winther) otherwise an isomeric dye stuff of little value will be obtained.
EXAMPLE.
3.435 kilos. of mononitrobenzidine are dissolved in 30 to 35 litres of water and
mixed with 4.5 kilos. of muriatic acid.
The mixture cooled down to 4° C. is added in the course of an hour, to a solution
of 2.1 kilos. of sodium nitrite in 10 litres of water.
The aqueous solution of the diazo compound thus formed, is introduced into a
solution of 2-2 kilos. salicylic acid and 8 kilos. soda salt in 20 litres of water at the
temperature of 0° to 5° C.
When the formation of the intermediate product is completed a solution of
4 kilos. of alpha naphthol alpha sulphonate of soda (Nevile & Winther) is added
at a temperature not above 10° C.
Twelve hours afterwards the temperature is raised to 20° C. and the solution is
allowed to stand for some hours.
"

page_text: The colouring matter thus formed is separated by warming and precipitating
with common salt.
It is a red brown powder not easily soluble in cold water, more readily soluble
in warm water, the aqueous solution is yellow red and dyes wool in an acid bath a
bright scarlet red tint.
Dark red shades are'obtained on wool mordanted with chromium salts.
The dyes resist the action of air, soap, fulling, chlorine and sulphurous acid.
An analogous dye stuff is obtained, if in the above mentioned example instead of
salicylic acid, 2-3 kilos. of o-cresotinic acid are used.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. The herein described process for the production of red azo colouring matters
by first combining one molecule of diazotised mono nitro benzidine (mono-o-nitro-
p-diamido diphenyl) with one molecule of salicylic acid and subsequent combination
of the thus obtained intermediate compounds with one molecule of alpha naphthol
alpha mono sulphonate of soda.
2. As new products the colouring matters manufactured as set forth in the
preceding claim.
Dated this 11th day of Anril 1803
ABEL & IMRAY,
Agents for the Applicant.