Production of Fast Yellow Dyestuffs from the Sulpho Acids of Dehydrothiotoluidine or analogous Bases.
Year: 1894

page_text: Date of Application, 26th Nov., 1894
Complete Specification Left, 24th Aug., 1895-Accepted, 28th Sept., 1895
PROVISIONAL SPECIFICATION.
The Production of Fast Yellow Dyestuffs from the Sulpho Acids of
Dehydrothiotoluidine or analogous Bases.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, (a communi-
cation to me from abroad by Leopold Cassella and Co., of 18 Liebigstrasse,
Frankfort on Main, in the Empire of Germany, Manufacturing Chemists,) do
hereby declare the nature of this invention to be as follows:-
My foreign correspondents have found that if the diazo derivatives of the sulpho
acids of dehydrothiotoluidine or of analogous thiazol-compounds are brought into
contact with hypochlorites in weakly alkaline solution, additional products are first
generated which no longer react with phenoles. Unlike the diazo compounds of
the named sulpho acids they easily decompose; slowly, if left standing for several
hours at usual temperature, and very rapidly, when slightly heated. Nitrogen is
developed and the brownish color of the intermediate product is gradually changed
into a pure yellow. An easily soluble yellow dyestuff is thus produced which
possesses great technical value as it dyes unmordanted cotton a yellow of great
fastness to light and capable of resisting the action of alkalies and chlorine.
As starting material the sulpho acid of dehydrothiotoluidine, the so-called
primuline, dehydrothioxylidinesulpho acid or similar substances may be used.
Example. 24,2 kilogrammes dehydrothiotoluidine of 191° melting point are
dissolved in 96 kilogrammes sulphuric acid at a temperature of 30-40° C. and
36 kilogrammes sulphuric acid containing 60 % anhydride are added at a
temperature of 50° C. When the sulphonation is completed, the sulpho acid is
separated by diluting the sulphonation with ice; it is then filtered off and dissolved
in water by means of carbonate of soda. The solution is acidulated with
46 kilogrammes muriatic acid and at a temperature of about 20° C. 7 kilogrammes
nitrite of soda are added. After half an hour the diazotation is terminated, the
diazo compound is added to a solution of 22 kilogrammes carbonate of soda and a
quantity of hypochlorite of soda corresponding to 17.7 grammes of chlorine.
After 12 hours standing the mixture is slowly heated to about 80° C. and the
dyestuff is precipitated with common salt.
Dated this 26th day of November 1894.
The Production of Fast Yellow Dyestuffs from the Sulpho Acids of
Dehydrothiotoluidine or analogous Bases.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, (a communi-
cation to me from abroad by Leopold Cassella and Co. of 19 Liebigstrasse,
Frankfort on Main, in the Empire of Germany, Manufacturing Chemists,) 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:-
My foreign correspondents have found that if the diazo derivatives of the

page_text: sulpho acids of dehydrothiotoluidine or of analogous thiazol-compounds are
brought into contact with hypochlorites in weakly alkaline solution, additional
products are first generated which no longer react with phenoles. Unlike the
diazo compounds of the named sulpho acids they easily decompose; slowly, if left
standing for several hours at usual temperature, and very rapidly, when slightly
heated. Nitrogen is developed and the brownish color of the intermediate product
is gradually changed into a pure yellow. An easily soluble yellow dyestuff is thus
produced which possesses great technical value as it dyes unmordanted cotton a
yellow of great fastness to light and capable of resisting the action of alkalies
and chlorine.
As starting material the sulpho acid of dehydrothiotoluidine, the so-called
primuline, dehydrothioxylidinesulpho acid or similar substances may be used.
Example. 24,2 kilogrammes dehydrothiotoluidine of 191° melting point are
dissolved in 96 kilogrammes sulphuric acid at a temperature of 30-40° C. and
36 kilogrammes sulphuric acid containing 60 % anhydride are added at a
temperature of 50° C. When the sulphonation is completed, the sulpho acid is
separated by diluting the sulphonation with ice, it is then filtered off and dissolved
in water by means of carbonate of soda. The solution is acidulated with
46 kilogrammes muriatic acid and at a temperature of about 20° C. 7 kilogrammes
nitrite of soda are added. After half an hour the diazotation is terminated, the
diazo compound is added to a solution of 22 kilogrammes carbonate of soda and a
quantity of hypochlorite of soda corresponding to 17,7 kilogrammes of chlorine.
After 12 hours standing the mixture is slowly heated to about 80° C. and the
dyestuff is precipitated with common salt.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. The production of yellow dyestuffs by the action of hypochlorites on the
diazo derivatives of the sulpho acids of dehydrothiotoluidine or analogous compounds
substantially as described.
2. The new yellow dyestuffs hereinbefore described.
A
1005