GB918366A - Azo dyestuffs - Google Patents

Abstract

2-Amino-benzene-sulphonic acid-N-phenyl-N-benzenesulphonyl imide is obtained by reacting 2-nitrobenzene sulphonic acid anilide with benzene sulphonic acid chloride and subjecting the product to catalytic hydrogenation. The product is used in azo dye preparation (see Group IV(c)).ALSO:The invention comprises azo dyestuffs of the general formula <FORM:0918366/IV (b)/1> wherein R denotes a radical of the benzene series to which the substituent -SO2- and -N=N- are linked ortho with respect to one another, X denotes a carbocyclic aryl or cycloalkyl radical, Y is a carbocyclic aryl radical and Z a hydrogen atom or an alkyl, carbocyclic aryl or aralkyl radical and the salts thereof and a process for the production thereof wherein the diazonium compound obtained by the diazotisation of an aromatic amine of the general formula <FORM:0918366/IV (b)/2> in which R, X and Y have the same meanings as above is coupled in an acid medium with a compound of the general formula <FORM:0918366/IV (b)/3> wherein 2 has the same meaning as above. The components specified in examples yield compounds of the first general formula above in which Y is phenyl, unsubstituted or substituted with a chlorine atom, a methyl group or -NHCOCH2Cl, X is phenyl, unsubstituted or substituted with one or two chlorine atoms, or a methyl, isopropyl, phenoxy or phenyl sulphonic group and Z is hydrogen, methyl, butyl or phenyl. The coupling is preferably carried out in aqueous acetic acid solution or suspension. Organic solvents such as formamide and dimethyl formamide may also be used. The products are red to bluish-red dyestuffs suitable for dying wool and polyamide fibres from an acid bath.