GB372562A - Process for the manufacture of azo dyestuffs - Google Patents

Abstract

Monoazo dyes are made by diazotizing the sulphuric esters of b -sulphaminoanthrahydroquinones or their nuclear substitution products and coupling with components free from sulphonic or carboxylic groups. The parent materials are obtained by esterifying b -aminoanthrahydroquinone or its nuclear substition products with chlorsulphonic acid; they can be diazotized without saponification of the sulphuric ester groups. The products dye wool from an acid bath or cotton from an alkaline bath, the dyeings being developed by treating with acid oxidizing agents such as sodium nitrite in hydrochloric acid or sodium dichromate in dilute sulphuric acid. Textiles may also be printed with pastes containing the dyestuffs, sodium chlorate and ammonium thiocyanate, the prints being developed by steaming. In examples, (1) the potassium salt of the sulphamic acid of 2-aminoanthrahydroquinone-9 : 10-disulphuric acid ester is diazotized and coupled with the o-anisidide of 2 : 3-oxynaphthoic acid; the product dyes in violet shades, changed to red on acid oxidation: a similar dyestuff is obtained from the sulphamic acid of 2-amino-3-bromanthrahydroquinone-9 : 10-disulphuric acid ester, and (2) the sulphamic acid of 2-aminoanthrahydroquinone-9 : 10-disulphuric acid ester is diazotized and coupled with (a) b -naphthol, to yield a product dyeing in brownish-red shades which change to orange on acid oxidation, or (b) 1-phenyl-3-methyl-5-pyrazolone, to give a product which dyes wool from an acid bath red shades, changing to reddish-yellow on acid oxidation.