GB614652A - Manufacture and use of polyazo-dyestuffs - Google Patents

Abstract

Polyazo dyestuffs are manufactured by treating aminoazo dyestuffs with phosgene, and using at least one aminoazo dyestuff of the formula R1-N=N-R2-N=N-R3-NH2 wherein R1 represents the residue of a hydroxybenzene-o-carboxylic acid free from sulphonic acid groups, R2 represents a residue of the benzene series containing a sulphonic acid group and having the azo groups in p-position to one another, and R3-NH2 represents the residue of an amine of the benzene series capable of coupling in p-position to the amino group. Such aminoazo dyestuffs may be prepared by coupling in alkaline medium a diazotized 1-amino-4-nitrobenzenesulphonic acid or monoacyl - p - phenylenediaminesulphonic acid (e.g. 1-amino-4-nitrobenzene-2- or -3-sulphonic acid or corresponding compounds containing an acylamino group in place of the nitro group) with a 1-hydroxybenzene-2-carboxylic acid (e.g. salicylic acid or 6-methyl-1-hydroxy-benzene-2-carboxylic acid), reducing the nitro group or hydrolysing the acylamino group, diazotizing, and coupling in acid medium with an amine of the benzene series coupling in p-position to the amino group, e.g. aniline (preferably as its o -methanesulphonic acid with subsequent hydrolysis), 1-amino-2-methoxy-5-methylbenzene, m - toluidine, 1 - amino - 2 : 5 - dimethoxybenzene or m-anisidine. The treatment with phosgene, to produce symmetrical or asymmetrical polyazo dyestuffs, may be carried out in an aqueous medium maintained alkaline in reaction. The products are suitable for dyeing and printing wool, silk, leather, artificial fibres from animal materials such as casein, superpolyamides and especially cellulose fibres such as cotton, linen, ramie, hemp and artificial silk or staple fibres of regenerated cellulose. They may be treated in substance, in the dyebath or especially on the fibre with agents yielding metal, e.g. copper, yielding mainly red dyeings. Examples describe the manufacture of symmetrical and asymmetrical p tetrakisazo dyes from certain of the components specified above, and of a trisazo dye in which the second aminoazo dyestuff is 41-hydroxy-31-carboxy-4-aminoazobenzene, and the after-coppered dyeing of cotton with the sodium salt of the dyestuff obtained by phosgenating the aminodisazo dyestuff 4-amino-41-hydroxy-31-carboxy-1 : 11-azobenzene-2-sulphonic acid --> 1 - amino - 2 - methoxy - 5 - methylbenzene. Specifications 455,274, 468,362 and 516,076 are referred to.