GB850844A - Improvements in or relating to acid monoazo dyestuffs of the diphenyl-azo-naphthalene series - Google Patents

Abstract

The invention comprises monoazo dyes of formula:- <FORM:0850844/IV (c)/1> wherein x and y are hydrogen or halogen atoms, or the trifluoromethyl group, or alkyl, alkoxy or alkylsulphonyl groups which contain less than 6 carbon atoms, R1 is an alkyl, alkoxy, cycloalkyl, cycloalkoxy, heterocyclic ether, aryl or heterocyclic radical which may be further substituted, R2 is a hydroxy group or an amino group which may be substituted and R3 is hydrogen or a phenyl radical which contains at least one alkyl, alkoxy or halogen substituent in the orthoposition. The dyes are prepared by diazotizing an appropriate 4-amino -4- acylaminodiphenyl and coupling with a 2-amino -8- naphthol -6-sulphonic acid or -sulphonamide. Alternatively a dye obtained by this method wherein R1-CO-is an acetyl radical may be hydrolysed and the resultant aminoazo dye treated with an acylating agent. The dyes give scarlet to red-violet shades on wool, silk, leather and polyamide fibres. In examples (1) the monoazo dyes 2 : 21-dimethyl-4-amino -41- acetylamino -1 : 11- diphenyl -5-sulphonic acid --> 2-amino -8- naphthol -6- N-methyl -N- phenyl-sulphonamide, 2 : 21-dimethyl -4-amino -41- carbodecycloxyamino -1 : 11-diphenyl -5- sulphonic acid --> 2-amino -8- naphthol -6- sulphonic acid and 2 : 21-dichloro -4-amino -41- carbo-octyloxyamino -1 : 11- diphenyl -5- sulphonic acid --> 2- (21 : 41 : 61-trimethyl)-phenylamino -8- naphthol -6- sulphonic acid are prepared; (2) the dye 4-amino -41 - acetylamino -2 : 21- dimethyl -1 : 11 diphenyl-5 -sulphonic acid --> 2-amino -8- naphthol -6-supphonic acid is hydrolysed with aqueous sodium hydroxide solution and the aminoazo dye treated in sodium bicarbonate solution with decyl chloroformate. Many further dyes are specified in a table.