Verfahren zur Herstellung von Sensibilisierungsfarbstoffen

Polymethine dyes having one of the general formula: or wherein R represents an alkyl or aryl group, A is an inorganic acid radical, X is O, S, Se or N-alkyl, Y is an alkyl or allyl group, Y1 and Y2 are alkyl groups and Z completes a heterocyclic ring, are prepared by any known methods from a 1-alkyl or aryl-5-methyl-1 : 2 : 3 : 4-tetrazole quaternary ammonium salt. In the examples a tetrazole quaternary ammonium salt is reacted with ethyl ortho-formate to give a symmetrical carbocyanine dye, with 2-acetanilidovinyl-5 : 6-dimethyl benzoxazole ethiodide, 2-phenylimino-ethylidene - 3 - ethyl - 5 : 6 - dimethyl benzthiazoline, 2 - phenylimino - ethylidene - 3-ethyl - 5 - methoxy benzselenazoline, or 2-phenylimino - ethylidene - 3 - ethyl - 5 - phenyl benzoxazoline to give an unsymmetrical carbocyanine dye, with 4 - dimethyl aminobenzaldehyde to give a styryl dye or with 5-(acetanilido - methylene) - 3 - methyl rhodanine, 5 - (acetanilido - methylene) - 3 - allyl rhodanine, 5 - (acetanilido - methylene) - 3-ethyl selenorhodanine, 5 - (acetanilido - methylene) - 3 - ethyl - oxazolidone, or 5 - (acetanilido - methylene) - 1 : 3 - dimethyl thiohydantoin to give a merocarbocyanine dye.