GB362513A - Process for the manufacture of azo dyestuffs - Google Patents

Abstract

Tetrakisazo dyes are made by tetrazotizing a benzidine disulphonic acid or dicarboxylic acid or a derivative thereof, coupling with two molecular parts of a middle component or with one molecular part each of two different middle components, again tetrazotizing and coupling with two molecular parts of similar or dissimilar N-alkylated or aralkylated 2 : 8-aminonaphthols substituted by one or two sulphonic acid groups or derivatives thereof or alternatively with one molecular part of one such component and one molecular part of a 2 : 8-aminonaphthol disulphonic acid or a derivative thereof. They yield deep printings on silk fast to water and sublimation. In examples the following dyestuffs are described: benzidine-o-disulphonic acid \sQ 1-methyl - 3-amino-4-methoxybenzene (2 mols.) \sQ 2 : 8-aminonaphthol-3 : 6-disulphonic acid (1 mol.) and n-butyl-2-amino-8-naphthol-6-sulphonic acid or hydroxyethyl-2-amino-8-naphthol-6-sulphonic acid (1 mol.) or aminoethyl - 2 : 8 - aminonaphthol - 3 : 6 disulphonic acid (2 mols.). Specification 319,407, [Class 2 (iii), Dyes &c.], is referred to. The N-alkyl-2 : 8-aminonaphthol sulphonic acids referred to above are prepared by boiling the corresponding aminonaphthol sulphonic acids with bisulphite and the corresponding alkylamines according to Bucherer's reaction.