GB404613A - The manufacture of azo-dyestuffs - Google Patents

Abstract

Azo dyes are made by linking one molecular proportion of an azo dyestuff derived from 4 : 4<1>-nitroaminostilbene- (or dibenzyl-)-2 : 2<1>-disulphonic acid with a different aromatic radicle (which may contain further azo groups) by means of an azo- or azoxy-group. The linking is effected by condensing the nitro group with an amine or by reducing the nitro group, diazotising and coupling. The dyestuffs which have affinity for cotton and leather may be subjected to the usual after-treatment processes in substance or on the fibre, e.g. with copper compounds. Metal compounds may be formed in the final coupling operation. In examples the following dyes are described: (1)--(4) the ethylated or methylated monoazo dyestuff 4 - nitro - 4<1> - aminostilbene - 2 : 2<1> - disulpho acid --> phenol is condensed with p-phenetidine in caustic soda (yellow on cotton), dehydrothiotoluidine sulphonic acid (orange), metanilic acid --> 1-methyl-3-amino-4-methoxybenzene, or sulphanilic acid --> 1-naphthylamine; the products may be oxidised, e.g. with hypochlorite, (5) the methylated and reduced dyestuff 4 : 4<1> - nitroaminostilbene - 2 : 2<1> - disulpho acid --> phenol --> K acid <FORM:0404613/IV/1> 4-nitro-2-aminophenol; the second coupling is made in presence of pyridine hydrochloride; the last component may be 5-nitro-2-aminobenzoic acid, 4-nitro- or 4-chlor-2-aminoanisole picramic acid or 6-chlor-4-nitroaminophenol; the phenol may be replaced by a yellow component, e.g. salicylic acid, acetoacetic anilide or by other components of the benzene and naphthalene series, (6) the methylated and reduced dyestuff 4 : 4<1> - nitroaminostilbene - 2 : 2<1> - disulpho acid --> phenol (2 mols.) \sQ K acid or resorcinol, (7)--(8) the methylated and reduced dyestuff of (5) <FORM:0404613/IV/2> J-acid <FORM:0404613/IV/3> o-anisidine or 4-nitro-2 - aminophenol or the same dyestuff <FORM:0404613/IV/4> J acid <FORM:0404613/IV/5> aniline; the former may be treated with copper compounds and the 4-nitro - 2 - amino - phenol may be replaced by 4 - nitro - 2 - amino - anisole, 6 - chlor - 4-nitro-2 - aminophenol or 4 : 6 - dinitro - 2 - aminophenol, (9) copper compound of the dyestuff 4 - chlor - 2 - aminophenol - 6 - sulphonic acid --> resorcinol \sM the methylated and reduced monoazo dyestuff of (5); the first component may be 2-chloraniline-4-sulphonic acid, (10) the dyestuff 4 : 4<1>-nitroaminostilbene-2 : 2<1>-disulpho acid --> a -naphthylamine --> salicylic acid is condensed with dehydrothiotoluidine-sulphonic acid or 4-aminoazobenzene-4<1>-sulpho acid in caustic soda solution.