GB622273A - Improvements in or relating to dyes and particularly photographic sensitising dyes - Google Patents

Abstract

Styryl dyes are prepared by condensing 4 mols. of a p-tertiary amino aromatic aldehyde containing a single aldehyde group with an alkylene bis quaternary salt of a heterocyclic nitrogen compound having two heterocyclic nitrogen nuclei linked through the quaternary nitrogen atoms by an alkylene group and having a reactive methyl group in the a - or g -position to each heterocyclic nitrogen atom. The condensation may be effected in the presence of an acid-binding substance, especially an organic amine having a dissociation constant greater than pyridine, e.g. ethylamine, diethylamine, piperidine, and diethylcyclohexylamine. The heterocyclic nuclei may be thiazole, oxazole, selenazole, iminazole, indolenine, dialkylindolenine, or pyridine nuclei, or nuclei having fused-on carbocyclic rings such as benzthiazole or quinoline nuclei, and may be linked by the use of polyfunctional hydrocarbon derivatives such as polyhalogen substituted alkanes, alkyl esters of alkylene sulphonic acids, alkyl disulphates, esters of sulphonic acids with polyhydric alcohols, and mixed compounds such as a - bromo - b - ethylsulphonates of ethane, and these derivatives may be substituted by nitro, primary or secondary amino, hydroxyl, carbonyl, thiocarbonyl, heterocyclic, or hydrocarbon groups. The aldehyde may be p-dimethylaminobenzaldehyde, o-methyl-p-diethylaminobenzaldehyde, 4-diethylamino-1-naphthaldehyde, 6 - diethylamino - 2 - naphthaldehyde, or p-N-morpholinobenzaldehyde. Hexamethylene-bis-[2 : 6-di-(p-dimethylaminostyryl)-pyridine]-dibromide is prepared by refluxing together hexamethylene-bis-(2 : 6 - lutidine) - dibromide, p - dimethylaminobenzaldehyde, piperidine, and alcohol. Trimethylene-bis-[2 : 4-di-(p-dimethylaminostyryl)-pyridine]-dibromide is similarly prepared. Specifications 334,706, [Class 2 (iii)], 573,394, 607,920, [Group IV (b)], 622,223, and 622,273 are referred to.