GB412102A - A manufacture of chromiferous azo-dyestuffs - Google Patents

Abstract

Chromiferous azo-dyestuffs are made by causing a chromiferous azo dye to react in an alkaline medium on the same azo dye free from chromium and containing at least once the residue of a coupling component whose coupling carbon atom belongs to a six-membered carbon ring. The dyes are superior in properties to those made in neutral or acid medium and give marine blue to black shades. In examples: (1) the dyestuff 1-amino-2-naphthol-4-sulphonic acid --> b -naphthol is chromed with chromium formate and then heated with the chromium free azo dye in presence of caustic soda (marine blue or wool); (2) the chromium compound of the dye from nitrated 1-diazo-2-naphthol-4-sulphonic acid and b -naphthol is heated with the chromium free dye in presence of caustic soda (black); (3) and (4) as in (1) using tetramethylammonium hydroxide and ammonia respectively. Examples of dyeing wool and silk and also of colouring a nitrocellulose varnish are given. Dyes from diazotized o - aminophenols, o - aminonaphthols, o - aminobenzene-or naphthalene carboxylic acids and diazotized amines which contain a salicylic group or their derivatives, e.g. sulpho, nitro, halogen or alkoxy compounds are specified. The usual inorganic and organic substances of alkaline action may be used in the condensation. The dyestuffs may be applied according to Specifications 364,148 and 408,497 and may be used for wool, silk, leather, cotton, regenerated cellulose, cellulose esters and ethers, varnishes, or as pigments or in printing. Specification 297,331, [Class 2 (iii)], also is referred to.