GB673791A - Improvements in the production of metal-containing polyazo dyestuffs - Google Patents

Abstract

Metallized leather dyes are obtained by coupling 1 mol. of 2 : 6-tetrazo-phenol-4-sulphonic acid with 2 mols. of a double-coupling component or 1 mol. each of a single- and a double-coupling component, coupling 1 mol. of the resultant disazo dyestuff with 2 mols. of one or 1 mol. each of two different diazo components or 1/2 mol. of 2 : 6-tetrazo-phenol-4-sulphonic acid and treating the resultant polyazo dyestuff with an agent yielding metal. The latter may be a salt of chromium, cobalt, iron, nickel, copper or other metal capable of forming complexes with o-o1-dihydroxyazo or o-hydroxy-o1-aminoazo compounds. In the examples: (1) 2 : 6-diaminochlorobenzene-4-sulphonic acid is tetrazotized and hydrolysed as in Specification 16811/01 to give 2 : 6-tetrazo-phenol-4-sulphonic acid which is coupled with 1 : 8-diaminonaphthalene; the diazo dyestuff is isolated, coupled with 2 mols. of diazotized sulphanilic acid and metallized with ferric chloride; (2) as in (1) but metallizing with chromic oxide and formic acid; (3) as in (1) using 1 : 5-diaminonaphthalene; (4) 2 : 6-tetrazo - phenol - 4 - sulphonic acid is reacted successively with resorcinol (2 mols.), diazotized p-nitraniline (1 mol.) and diazotized sulphanilic acid (1 mol.); the tetrakisazo product is metallized with ferric chloride; (5) as in (4) using 1 : 8-diaminonaphthalene-2-sulphonic acid in place of resorcinol and metallizing with chromic oxide and formic acid; (6) as in (5) using a second mol. of p-nitraniline in place of sulphanilic acid; ferric chloride may also be used for metallizing; (7) 2 : 6-tetrazophenol-4-sulphonic acid is coupled with 2-naphthol-6-sulphonic acid and resorcinol (1 mol. each); a further 1/2 mol. of 2 : 6-tetrazo-phenol-4-sulphonic acid is added and the hexakisazo product metallized with ferric chloride. Other suitable components are listed.