GB462629A - Manufacture of dyestuffs - Google Patents

Abstract

Azo dyes; acid wool dyes without mordants, dyeing with.--Azo dyestuffs are manufactured by coupling a diazo-compound with an aldehyde bisulphite compound of 2-amino-8-naphthol-6-sulphonic acid in alkaline, neutral or acid medium. Suitable diazo components are aniline, toluidines, anisidines and sulphonic acids thereof, their substitution products containing a nitro-group in p-position to the amino-group, and particularly compounds nitrated in p-position to the amino-group and containing in o-position a sulphone-alkyl or -aralkyl group, e.g. 1-amino-4-nitrophenyl-2-methyl, -ethyl or benzyl sulphone, or substitution products thereof, e.g. those containing halogen, alkyl, alkoxy or nitro-groups. The products dye animal fibres, e.g. wool and silk, advantageously in the presence of sulphuric acid or of capillary active substances containing in their kation a basic nitrogen atom and an aliphatic or araliphatic residue of more than 8 carbon atoms. Examples describe the manufacture of the following dyestuffs: (1) 1-amino-4-nitrophenyl-2-methyl sulphone --> the sodium salt of the formaldehyde bisulphite compound of 2 : 8 : 6-acid; the product dyes wool or silk in an acid bath blue shades; (2) 1-amino-4-nitrophenyl-2-benzyl sulphone --> the same coupling component or the corresponding potassium or other salt (somewhat more greenish-blue shades); the diazo-component may be replaced by the 2-ethyl sulphone, by nitrated amines such as p-nitraniline or p-nitro-o-chloraniline (violet shades), by p - nitraniline - o - sulphonic acid (reddish-blue shades), or by simpler amines such as aniline, sulphanilic acid, naphthionic acid or monobenzoyl - p - phenylenediamine (orange to red); the coupling component may be replaced by the corresponding acetaldehyde or furfural bisulphite compound. In example (3), wool is dyed blue with the product of (1) from a bath containing sodium sulphate and sulphuric acid. Specifications 11343/99, [Class 2], 433,230, 436,790, 436,863, 439,890, and 451,970 are referred to. Aldehyde bisulphite compounds of 2 : 8 : 6-acid are manufactured by reacting the acid or a salt thereof with an aldehyde bisulphite compound. 1-Amino-4-nitrophenyl-2-methyl, -ethyl and benzyl sulphones are obtainable by reacting sodium 1 - chloro - 4 - nitrobenzene - 2 - sulphinate with methyl bromide, ethyl bromide or benzyl chloride respectively, and heating the products with aqueous ammonia under pressure.