Polymethine dyes, process of making them and photographic elements containing them

摘要

Polymethine dyes having the general formula wherein R is an alkyl or substituted alkyl group of 1 to 6 carbon atoms or an aralkyl or allyl group, Z completes a 5- or 6-membered heterocyclic nucleus, d is 0 or 1, n is 1, 2 or 3, Q is a pyridinium or quinolinium group, substituted or not, and joined to the carbon atom through its nitrogen atom, and X is an anion, are prepared by condensing a cyclammonium salt of the formula II wherein R2 is an acyl group, R3 is an aryl group and Y is an anion, with a pyridinium or quinolinium salt of the formula III wherein Y1 is an anion. Examples are given of dyes wherein Z completes a benzthiazole, benzoxazole or 4-quinoline nucleus, The pyridinium group Q may carry a bromine atom or methyl group in the 3-position or a phenyl substituent.