GB418622A - Manufacture of chromiferous dyestuffs - Google Patents

Abstract

Azo dyes, chromium compounds of; acid wool dyes, dyeing with.--Chromiferous azo dyestuffs are obtained by treating, in presence of a soluble salt of an organic acid, an azo dyestuff of the general formula HO--R1--N = N--R2, wherein R1 is a sulphonated naphthalene residue, R2 is a naphthol residue and the hydroxyl group of the residue R1 is in o-position to the azo bridge, with an agent yielding chromium used in such proportion that there is less than one atomic proportion of chromium for each chromable group in the dyestuff molecule. The products give fast level blue to black shades on animal fibres, e.g. wool or silk. The treatment may be effected in an open vessel or under pressure and with or without further additions such as an inorganic salt or organic or inorganic acid, in neutral or acid medium. Specified agents yielding chromium are the chloride, fluoride, sulphate, sulphite, acetate, formate, oxalate and benzenesulphonate or mixtures thereof. Specified soluble salts of organic acids are sodium, potassium or ammonium formate, acetate, propionate, oxalate, succinate, malonate, hexahydrobenzoate, hexahydrophthalate, o -benzylsulphonate, N-o -methylsulphonates and the corresponding salts of amino-, oxy- and aminooxy-acids, halogenated or nitrated acids, oxamino - acids, aminosulphonic acids of the benzene, naphthalene or anthracene series aminonaphtholsulphonic acids, benzoic and phthalic acids, oxybenzoic sulphosalicylic, sulphoaminosalicylic and sulphophthalic acids. The following examples are specified: (1) 46,1 parts by weight of the azo dyestuff from nitrated 1 : 2-diazonaphthol-4-sulphonic acid and 2-naphthol are boiled for 5 hours under reflux with a solution containing caustic soda, sodium formate and chromium fluoride corresponding to 5,32 parts of Cr2O3 and the solution is evaporated in vacuo; the product dyes wool fast black tints from a bath containing an organic acid and sulphuric acid. (2) 4,16 Parts of the azo dyestuff 2 : 1-aminonaphthol - 4 - sulphonic acid --> 2 - naphthol is boiled under reflux with a solution containing caustic soda, chromium formate corresponding to 0,42 part of Cr2O3, and the disodium salt of 1 - oxy - 4 - sulphobenzene - 2 - carboxylic acid, and the solution is filtered and concentrated and the dyestuff salted out; the product dyes wool fast marine blue tints. Examples of the dyeing processes for wool and loaded or unloaded silk are also given. Specifications 269,522, [Class 2 (iii)], 364,148, and 408,497 are referred to.