GB456768A - Process for the manufacture of polyazo dyestuffs - Google Patents

Abstract

Polyazo dyes are made by coupling 1 mol. of a naphthol sulphonic acid capable of coupling both in an acid and in an alkaline medium, in either order, with 1 mol of a tetrazodiphenyl and 1 mol. of a diazo compound, one of the couplings being effected in an acid and the other in an alkaline medium, combining the diazo disazo compound obtained with 1 mol. of resorcinol or a derivative thereof, and causing the trisazo dyestuff to react in an alkaline medium with 1 mol. of a monodiazo compound or at the same time or successively with 2 mols. of the same or different monodiazo compounds. Instead of the tetrazodiphenyl a diazo compound of the benzene series containing a group which is convertible into an amino group may be used. They yield brown to blackish brown shades on leather fast to acids and alkalies. In the examples the following dyes are described: (1) sulphanilic acid --> (alk.) H acid \sM (acid) benzidine --> resorcinol \sx p-nitroaniline; (2) 4-nitroaniline-2-sulphonic acid is used instead of sulphanilic acid in (1); this component and the p-nitroaniline may also be substituted by aniline disulphonic acids, naphthionic acid, naphthylamine disulphonic acids, chloraniline sulphonic acids, anisidine sulphonic acids, aminoazobenzene mono- or disulphonic acids, etc.; (3) sulphanilic acid (1 mol.) and p-nitroaniline (1 mol.) are used as end components in (1); p-nitraniline disulphonic acids, substituted anilines and aniline sulphonic acids, picramic acid and 1 : 3-diamino-4-nitrobenzene may also be used; (4) sulphanilic acid --> (alk.) J acid \sM (acid) benzidine --> resorcinol \sx 4-nitroaniline-2-sulphonic acid (1 mol.) and p-nitroaniline (1 mol.); p-aminobenzoic acid, 1-hydroxy-4-aminobenzene-2-carboxylic acid &c. may also be used as components; (5) sulphanilic acid --> (acid) J acid \sM (alk.) benzidine --> resorcinol \sx 4-nitraniline-2-sulphonic acid (1 mol.) and p-nitroaniline (1 mol.); (6) sulphanilic acid --> (alk.) J acid \sM (acid) p-nitroaniline (reduced) --> resorcinol \sx 4-nitraniline-2-sulphonic acid (1 mol.) and p-nitroaniline (1 mol.); (7) H acid is used instead of J acid. Further similar combinations are specified in a table. Other double coupling components mentioned are 1-amino-8-naphthol-4 - sulphonic acid, phenyl J acid and 2 : 5-dihydroxynaphthalene - 7 - sulphonic acid and other diaminodiphenyls are m-nitrobenzidine and benzidine-m-disulphonic acid.