GB706157A - Manufacture of new trisazo-dyestuffs - Google Patents

Abstract

The invention comprises trisazo dyes of the general formula <FORM:0706157/IV(c)/1> (wherein R1 represents an aromatic residue of the benzene series and R2 the residue of a hydroxynaphthalene, R1 and R2 each containing at least one and together at least three sulphonic acid groups and R2 being free from further substituents), and the manufacture thereof by coupling a naphtholsulphonic acid R2H with a diazoazo compound of the general formula <FORM:0706157/IV(c)/2> (wherein X represents a diazotized amino group), which is obtainable by one-sided coupling of tetrazotized benzidine with 1-amino-8-naphthol-3 : 6-disulphonic acid in an acid medium, followed by alkaline coupling of the product with the diazo compound of an amine R1-NH2. The products dye chrome-tanned leather in navy blue tints. Specified components, some of which are used in examples (1)-(3) are: amines R1-NH2: aniline-2-, -3- and -4-sulphonic acids and -3 : 5- and -2 : 5-disulphonic acids; naptholsulphonic acids R2H: 1-naphthol-4- and -5-sulphonic acids and -3 : 6-, -3-8- and -4 : 8-disulphonic acids, and 2-naphthol-6- and -7-sulphonic acids and -3 : 6- and -3 : 8- disulphonic acids. In example (4), velour leather is dyed reddish navy blue with the dyestuff sulphanilic acid --> (alkaline) H-acid (acid) \sM benzidine --> (alkaline) 2-naphthol -3 : 6-disulphonic acid from an aqueous bath to which formic acid is added in the later stages.