GB389758A - Manufacture of dyestuffs - Google Patents

Abstract

Azo dyes; cellulose esters or ethers, dyeing.--Azo dyes suitable for dyeing cellulose ester or ether materials are produced in substance by coupling diazotized 4-nitro-2-chloraniline with an N-alkyl-o -sulphonic acid of a non-sulphonated mononuclear primary amine of the benzene series containing no substituent in m-position to the amino group and splitting off the alkyl-o -sulphonic group. The products dye acetate silk pure orange to red orange shades fast to light and washing. They are preferably used in finely subdivided form obtained by grinding to form a paste with water containing a dispersing agent such as a sulphonated residue from the manufacture of benzaldehyde or turpentine (cf. Specification 271,898, [Class 2 (iii), Dyes &c.]. Such pastes may be converted into dry preparations, which can be powdered, by cautious drying in vacuo in presence of a further quantity of the same dispersing agent or another such as sulphite cellulose lye. In an example diazotized 4-nitro-2-chloraniline is coupled in the cold with the sodium salt of the o -methanesulphonic acid of aniline, o-toluidine or o-anisidine and the product is heated with caustic soda solution to split off the methyl-o -sulphonic group. Specifications 11343/99, [Class 2, Acids and salts, Organic &c.], and 200,873, [Class 2 (iii), Dyes &c.], also are referred to.