Patent GB-810736-A (GB)
Title: Improvements in the production of monoazo heterocyclic dyestuffs
IPC: C09B27/00
Filed: 1956-03-23
Abstract: A process for the production of monoazo dyestuffs consists in subjecting to the action of an oxidizing or dehydrogenating agent a mixture of about equivalent amounts of an organic compound capable of being azo-coupled and of a heterocyclic hydrazone or hydrazine compound of tautomeric formula <FORM:0810736/IV (c)/1> wherein X is a divalent ring atom which may be substituted, such as -O-, -S- or -CR2-(R being methyl or ethyl) and Y is an ethylene, alkyl- or aryl-substituted ethylene, o-phenylene or naphthylene radical which may contain one or more halogen atoms or alkyl, alkoxy, nitro, cyano, amino, acylamino, carboxylic or sulphonic acid groups.  For example, when a mixture of alphanaphthol and 2-hydrazino benzthiazole is treated with potassium ferricyanide in a solution made alkaline with ammonia the reaction proceeds as follows <FORM:0810736/IV (c)/2> Specified hydrazino compounds and coupling components other than those in examples, are 2 - hydrazino - 6 - benzoylamino - or 5 - bromo-or 7 - chloro - or cyano - or 5 - or 7 - methoxybenzthiazole, 2 - hydrazino - 4 - p - tolyl - thiazole and 2 - hydrazino - benzoxazole - 5 - sulphonic or carboxylic acid: phenols, naphthols; aromatic amines such as aniline, N : N-diethylaniline, N-benzylaniline, diphenylamine, toluidines and anisidines; aminophenols and aminonaphthols and enols such as dibenzoylmethane, dihydroresorcinol and rhodanines.  Specified oxidizing agents are potassium and sodium ferricyanide, ferric salts, cupric salts, mercuric salts, ceric salts, hypochlorites, lead dioxide, persulphates, perborates, hydrogen peroxide and oxygen (e.g. in air). Ferrous salts are specified as oxidation catalysts.  The process may also be carried out on the fibre.  In examples: (1) 2-hydrazino - benzthiazole or 2 - hydrazinobenzoxazole and alpha-naphthol are dissolved in aqueous methanol with the addition of ammonia and oxidized with potassium ferricyanide; (2) 2-hydrazino-6-nitrobenzthiazole and alpha - naphthol, 1 - phenyl - 3 - methyl-5-pyrazolone, acetylacetone, dimedone, malonodinitrile, barbituric acid, 8-hydroxyquinoline or ethyl acetoacetate are dissolved in dimethylformamide and oxidized with lead dioxide; (3) 2 - hydrazino - 6 - nitrobenzthiazole and alpha-naphthylamine are dissolved in normal hydrochloric acid and oxidized with hydrogen peroxide in the presence of ferrous sulphate to give the corresponding dyestuff hydrochloride; the following components are oxidized in similar process: 2-hydrazinobenzthiazole, 2-hydrazino - 6 - methoxy - or ethoxy - or cyano - or acetylamino - or nitro - or aminobenzthiazole, 2 - hydrazino - 6 or 7 - methylbenzthiazole, 2 - hydrazino - 7 - chloro - 5-methyl - benzthiazole, 2 - hydrazinobenzoxazole, 2 - hydrazinothiazole, 2 - hydrazino - 4-phenylthiazole, 2 - hydrazino - 4 : 5 - diphenyl-or dimethyl - thiazole, 2 - hydrazino - 2 : 5-(11 : 21 - or 21 : 11 - naphtho) thiazole, 2 - hydrazino - 3 : 3 - dimethyl - indolenine, 2 - hydrazino - 5 - chloro - or bromo - or methoxy-or nitro - or benzoylamino - 3 : 3 - dimethylindolenine, 2 - hydrazino - 6 - methoxy - 3 : 3-diethyl - indolenine and 2 - hydrazino - 6-acetylamino - 3 : 3 - dimethyl - indolenine; alpha - naphthylamine, m - toluidine, N - ethyldiphenylamine, N - ethyl - p - ethoxy - diphenylamine, N : N - dimethyl - or diethylaniline, N - methyl - N - beta - hydroxy - or chloro - ethyl - aniline, N - n - butyl - N - betacyanoethyl - aniline, N : N - di(betahydroxyethyl) - aniline, 1 : 2 - dimethylindole, 1-methyl - 2 - phenyl - indole, 1 : 2 : 3 : 4 - tetrahydro - 3 - hydroxy - 7 : 8 (11 : 21) (61 - hydroxybenzo) quinoline, N : N - diethyl - 3 - cyanoaniline and N : N - dimethyl - alpha - naphthylamine.