GB438445A - Process for the manufacture of o-aminoazo-dyestuffs - Google Patents

Abstract

o-Aminoazo dyes are prepared by reducing with ferrous salts in an alkaline medium the o-nitroazo dyes obtainable from aromatic o-nitrodiazo compounds and any coupling components. Examples are given of the reduction of the following dyes: 91) 2-nitraniline-4-sulphonic acid or o-nitroaminotoluenes --> 2-naphthol or its sulphonic acids or other derivatives; 92) 2-nitraniline or its sulphonic acids --> 1-naphthol-4-sulphonic acid or other 1-naphtholsulphonic acid; (3) 2-nitraniline-4-sulphonic acid or other derivative of 2-nitraniline --> 2-naphthylamine or its sulphonic acids; (4) 2-nitraniline or its derivatives --> 2 : 8-aminonaphthol-6-sulphonic acid (acid coupling) or its derivatives capable of coupling in an acid medium in o-position to the amino group; (5) 2-nitraniline or its derivatives --> 1 : 8-aminonaphthol - 3 : 6 - disulphonic acid (acid coupling); (6) 2-nitraniline-4-sulphonic acid or its derivatives --> 1-phenyl-3-methyl-5-pyrazolone or its sulphonic acids or other derivatives, or b -ketocarboxylic esters or arylides; (7) 2-nitraniline or its derivatives --> 1 : 8 - dioxynaphthalene - 3 : 6 - disulphonic acid or other 1 : 8-dioxynaphthalenesulphonic acid; (8) 2-nitraniline or its derivatives --> 1-naphthylamine-4-sulphonic acid or its derivatives; (9) 2-nitraniline or its derivatives --> 2 - acetylamino - 8 - naphthol - 6 sulphonic acid or other N-substitution product of 2-amino-8-naphthol-6-sulphonic acid; (10) 2-nitraniline or its derivatives --> 1 : 8-naphthylenediamine-4-sulphonic acid; (11) 2-nitraniline --> 1 : 8-dioxynaphthalene-4-sulphonic acid, coupled in the presence of sodium acetate; (12) a disazo dye obtained by coupling diazotized 2-nitraniline or a derivative thereof in an acid medium with an equimolecular amount of 1 : 8-aminonaphthol-3 : 6-disulphonic acid, and coupling the product in an alkaline medium with the diazo compound of aniline or other diazotizable base. Samples have been filed under Sect. 2 (5) of o-aminoazo dyes prepared by reducing the following dyes: (1) 2-nitro-3-aminocarbazole --> 1-naphthol-3 : 6-disulphonic acid; (2) 4 - amino - 3 - nitrobenzophenone - 2<1> - carboxylic acid --> 1-naphthol-3 : 8-disulphonic acid.