GB424262A - Manufacture of azo-dyestuffs suitable for dyeing leather - Google Patents

Abstract

Disazo dyes; acid wool and mordant dyes, dyeing with.--Disazo dyes, suitable for dyeing leather full yellow to brown shades, are obtained by coupling a diazotized aminosulphosalicylic acid and a diazotized aromatic amine containing at least one nitro group with a phenol or naphthol containing a single benzene or naphthalene nucleus and capable of coupling twice in an alkaline medium. The processes and products of Specifications 384,800 and 403,022 are disclaimed. Specified aminosulphosalicylic acids are those in which NH2 : OH : SO3H : COOH = 4 : 1 : 6 : 2 and 6 : 1 : 4 : 2. Specified nitro aromatic amines are 4-nitraniline, 4-nitro-2-aminophenol, 4 : 6-dinitro-2-aminophenol, 4-methyl-3-nitraniline, 5-chloro-2-nitro - 1 - methyl - 2 - aminobenzene, 1 - amino - 4-nitronaphthalene-6- or -7-sulphonic acids and substitution products thereof. Specified coupling components capable of coupling twice are monohydroxy compounds of the benzene series, resorcinol, 1 : 3-dihydroxybenzene-4-carboxylic acid, 1 - naphthol and 2 : 7 - dihydroxynaphthalene. The examples relate, (1) to the manufacture of the dyestuff 6-amino-1-hydroxy-4 - sulphobenzene - 2 - carboxylic acid --> 1 : 3-dihydroxybenzene-4-carboxylic acid \sM 4 : 6-dinitro-2-aminophenol; (2) to the dyeing therewith of a deacidified chrome leather from a bath containing formic acid. Specifications 10536/03, [Class 2], 28910/13, [Class 141], 234,956 and 285,097, [both in Class 2 (iii)], also are referred to. The Specification as open to inspection under Sect. 91 comprises also the use as second diazo components of other than nitro-substituted aromatic amines and specifies the use of o-chloraniline and naphthionic acid. This subject-matter does not appear in the Specification as accepted.