GB449478A - Manufacture and application of azo-dyestuffs - Google Patents

Abstract

Chromiferous azo dyes are made by heating with an acid, other than an aliphatic acid, in an aqueous medium the complex chromium compounds of azo dyes of the formula <FORM:0449478/IV/1> wherein the three x's represent hydrogen atoms, of which at least one is exchanged for a sulphonic acid group and R = the residue of a coupling component containing a group capable of binding metal in complex union, the said heating being so conducted that the SO3H group in 4-position is exchanged for hydrogen. The parent dyestuffs may be present in admixture either with each other or with other azo dyes capable of complex metal formation. In many cases it is possible to make the complex chromium compound and to heat it with an acid in aqueous medium in one operation. The products may be used for dyeing or colouring wool, silk, leather, varnishes made from cellulose, natural or artificial p resins, or they may be used as pigments or in printing. In examples the chromium compounds of dyes from the following components are treated with aqueous solutions of the following acids: 2-amino-1-naphthol - 4 : 8 -, 4 : 6- and 4 : 7 - disulphonic acids; a - or b -naphthol, 1-naphthol-8-sulphamide, 1 - (2<1> - methyl - 4<1> - sulpho) - or 1 - (3<1> - sulpho) - phenyl - and 1 - phenyl - 3 - methyl - 5 - pyrazolones, 1 - phenyl - 5 - pyrazolone - 3 - carboxylic acid, 2 - naphthol - 3 - carboxylic acid, 1 - naphthol - 8 - sulphonic acid, barbituric acid; naphthalene - 1 - or 2 - sulphonic acid, naphthalene-1 : 5-disulphonic acid, a - and b - naphthol mono- and poly-sulphonic acids, benzene mono-, di- and poly-sulphonic acids, sulphuric and other mineral acids, naphthalene di- and poly-sulphonic acids, 2-naphthol- 6-sulphonic acids, hydrochloric acid, benzene-sulphocarboxylic acids, phosphoric acid. In further examples the dyestuff 2-amino-1-naphthol-4 : 8-disulpho acid --> b -naphthol is heated with neutral chromium sulphate and naphthalene-1-sulphonic acid or other chroming agents and acids, e.g. chromium naphthalene-1- or 2-sulphonate or 1 : 5-disulphonate or with aqueous neutral chromium sulphate only. According to the Provisional Specification complex metal compounds of azo dyes are made by heating in an aqueous medium the metal compound of an azo dye of the above general formula wherein the three x's represent hydrogen atoms, of which at least one may be exchanged for a sulpho group and R may also represent the residue of a diazo component. In the latter case the parent azo dyes are made by coupling a diazo compound of the benzene or naphthalene series containg one or more groups capable of binding metal in complex union, with a 1-naphthol-4-sulphonic acid, e.g. the 4 : 6-, 4 : 7- or 4 : 8-disulphonic acid.