Dimethine dyestuffs, their preparation and their use for dyeing synthetic and natural materials

Claim 1

A styryl dyestuff of the formula ##STR25## in which R is a lower alkyl or alkenyl group which can be substituted by a non-ionic radical, R 3 is a C 1 - to C 4 -alkyl, which can be substituted by phenyl or C 1 - to C 4 -alkoxycarbonyl, C 3 - or C 4 -alkenyl, which can be substituted by phenyl, C 2 - to C 4 -alkyl, which is substituted by one hydroxyl, C 1 - to C 4 -alkoxy, phenoxy, benzyloxy, benzoyloxy, benzamido, phenylsulphamido, mesylamino, C 1 - to C 3 -alkylcarbonyloxy, C 1 - to C 4 -alkylcarbamoyloxy, phenylcarbamoyloxy, chlorine or cyano radical, or C 3 - or C 4 -alkyl, which is substituted by one or two hydroxyl, methoxy, ethoxy, acetoxy or chlorine radicals, it being possible for the phenyl radicals in turn to be substituted by one hydroxyl, C 1 - to C 4 -alkoxy, C 1 - to C 4 -alkoxycarbonyl, C 5 - or C 6 -cycloalkyl, benzyl, 2-phenylprop-2-yl, phenoxy, benzyloxy, phenylmercapto, phenylsulphonyl, nitro or cyano radical or by 1 to 3 fluorine, chlorine, bromine or C 1 - to C 4 -alkyl radicals, W 1 , W 2 , W 3 and W 4 each independently is hydrogen or C 1 - to C 4 -alkyl, and W 1 can also represent phenyl, W 3 can also represent chlorine, W 1 and W 3 together can form the remaining members of a cyclohexane ring, or W 3 and W 4 together can form the remaining members of a cyclopentane or cyclohexane ring, Z is O, S, N-W 5 or ##STR26## m is 0, 1 or 2, W 5 , W 6 and W 7 each independently is H or C 1 - to C 4 -alkyl, ring B can be substituted by C 1 - to C 4 -alkyl, and An - is an anion.