GB643354A - Manufacture of new monoazo-dyestuffs - Google Patents

Abstract

Monoazo dyestuffs are manufactured by coupling a diazotized 4-nitro-6-acylamino-2-aminophenol with a hydroxybenzene containing an aliphatic hydrocarbon in p-position to the hydroxy group, advantageously in an alkaline medium, if desired with the addition of a neutral or basic solvent (e.g. alcohol, pyridine or ethanolamine), or by reducing a dyestuff obtained similarly from diazotized 4 : 6-dinitro-2-aminophenol (e.g. by means of an alkali sulphide or hydrosulphide) so as to convert the nitro group in o-position to the hydroxy group into an amino group, which is then acylated (e.g. by means of an acid halide or anhydride). In either case the acyl residue may be aromatic or especially aliphatic, examples being formyl, acetyl, oxalyl, sulphobenzyl and phthalyl. The products may be used for dyeing or printing various fibres, especially those of animal origin such as wool, silk or leather. They may be treated in substance, in the dye bath or on the fibre with agents yielding metal, e.g. chromium. In examples: (1) 4 - nitro - 6 - acetylamino - 2 - aminophenol is diazotized and coupled with p-cresol in the presence of sodium hydroxide and pyridine; (2) the sodium salt of the dyestuff 4 : 6 - dinitro - 2 - aminophenol --> p - cresol is warmed with sodium hydrosulphide and sodium hydroxide in water and the product is heated with acetic anhydride; (3) and (4) wool is dyed brown with the product of (1) by the afterchrome and single bath chroming processes. Additional coupling components specified are 4-isopropyl-, 2 : 4- and 3 : 4-dimethyl- and 2-acetylamino - 4 - methyl - phenol. Specification 637,404 is referred to. Samples have been furnished under Sect. 2 (5) of the dyestuffs obtained by coupling diazotized 4 - nitro - 6 - acetylamino - 2 - aminophenol with (I) 1 : 2-dimethyl-4-hydroxybenzene (in an aqueous suspension of calcium hydroxide); (II) p-tert.-amylphenol; and (III) p-sec.-butylphenol. The Specification as open to inspection under Sect. 91 comprises also the use as diazo components of 6-nitro-4-acylamino-2-aminophenols and as coupling components of other hydroxybenzenes coupling in o-position to the hydroxy group, e.g. 4-acetylamino-3-methyl-, 4-acetylamino-3 : 5-dimethyl- and 4-chloro-phenol. This subject-matter does not appear in the Specification as accepted.