GB791443A - New disazo dyestuffs derived from bis-aminopyrazoles - Google Patents

Abstract

The invention comprises dyestuffs of formula <FORM:0791443/IV (b)/1> where N-X-N is the residue of a 4,41-diaminodiphenyl optionally substituted by methyl or methoxy groups and R is a naphthalene or benzene residue containing 1 or 2 SO3H groups and may be further substituted but not with OH or NO2 groups. They are made by coupling appropriate bis-aminopyrazoles with diazotized 4-nitroaniline-2-sulphonic acid and diazotized amines of formula RNH2. Advantageously the first stage coupling is effected in an acidic aqueous medium and the second stage in an aqueous medium at pH 3.5-9 or 7-0 when, as is preferred, diazotized RNH2 is used in this stage. Specified bis-aminopyrazoles are 4,41 - bis - (511 - amino - 311 - methyl - 111-pyrazolyl)-diphenyl, -2,21- and -3,31-dimethyldiphenyl and -3,31-dimethoxy-diphenyl. Specified amines RNH2 are 2-, 3- and 4-aniline sulphonic acids, 2-chloroaniline-5-, 2,5-dichloroaniline-4-, 2,4-dimethyl and 3,4-dichloroaniline6-, 4-acetylamino- and methyl-aniline-2-, 4chloro-3-methyl- and 3-chloro-4-methyl-aniline6-, and 3-phenoxyacetyl- and -benzoyl-aminoaniline-6-sulphonic acids, 1-naphthylamine-2-and -4- and 2-naphthylamine-4,8-di-sulphonic acids. The dyestuffs dye wool from a weakly acid or neutral dye bath in orange shades. Silk, leather and fibres of superpoly-amides and -urethanes may also be dyed. In examples illustrative of the preparation and their use in dyeing wool the reactants are chosen from those specified above 3 - aminobenzenesulphon - N -ethylanilide-4-sulphonic acid being an additional amine corresponding to RNH2.