GB695534A - Process for the preparation of polyazo dyestuffs - Google Patents

Abstract

Polyazo dyestuffs are made by coupling tetrazotized o-dianisidine with 1 mol. of a compound of the formula <FORM:0695534/IV (c)/1> (or its copper complex) and 1 mol. of the same or another coupling component, and coppering the product in substance or on the fibre; R is the residue of an o-coupling naphthol (which may contain 1-3 sulphonic acid groups) or pyrazolone. Coppering in substance may be carried out in aqueous alkaline solution with a copper-tetrammine complex or in the melt with alkali salts of aliphatic acids with copper salts. The products dye cotton and regenerated cellulose in blue-grey or green-grey shades. In the examples, tetrazotized o-dianisidine is coupled with the following: (1) 1-naphthol-3 : 6-di-sulphonic acid and the copper complex of the dyestuff : 1 : 5 - dihydroxy - 2 - naphthylamine-7 - sulphonic acid --> 1 - naphthol - 4 - sulphonic acid; (2) 1-naphthol-4-sulphonic acid and the copper complex of the dyestuff: amine of (1) --> 1-naphthol-3 : 6-disulphonic acid; (3) chromotropic acid and the copper complex of the dyestuff: amine of (1) --> 1-(p-sulphophenyl) - 3 - methyl - 5 - pyrazolone; (4) copper complex of the monoazo dyestuff of (2) and 1-(p-sulphophenyl) - 3 - methyl - 5 - pyrazolone; (5) 2 mols. of the copper complex of the dyestuff: amine of (1) --> 2-naphthol-4-sulphonic acid. Coupling with the copper complex takes place in a mixture of pyridine and aqueous ammonia. A table is given of other dyestuffs made in the same way and further suitable components are listed.