GB719631A - Manufacture of azo-dyestuffs - Google Patents

Abstract

The invention comprises (1) the production of azo dyestuffs by coupling a diazo component in alkaline solutions with a p-aminosalicylic acid of the formula:- <FORM:0719631/IV(c)/1> and (2) monoazo, disazo and trisazo dyestuffs of the following formulae:- <FORM:0719631/IV(c)/2> and <FORM:0719631/IV(c)/3> where there is at least one solubilising group in one of the residues R; in all the formulae X and Y are hydrogen, chlorine, methyl or sulphonic acid. The disazo and trisazo dyestuffs are made by diazotizing the monoazo compounds and coupling with suitable components, and repeating the process if necessary. The products may be metallized (especially chromed) in substance or on the fibre, e.g. by the metachrome process. Examples show the production of the following dyestuffs:- 4-chloro-2-aminophenol --> 4-aminosalicylic acid, 6-nitro-2-aminophenol-4-sulphonic acid --> 4-aminosalicylic acid, sulphanilic acid --> 4-aminosalicylic acid --> 1-phenyl-3-methyl-5-pyrazolone, and sulphanilic acid --> 4-aminosalicylic acid --> 1-naphthylamine --> 2-naphthol. Other suitable starting materials are listed:- diazo components of the benzene and naphthalene series, end components for disazo (and middle components for trisazo) of the benzene, naphthalene and pyrazolone series, and as end components for trisazo resorcinol, naphthols and phenylmethylpyrazolone. Substituted 4-aminosalicylic acids are also mentioned.