Improvements in photographic emulsions and in the manufacture of dyes therefor

摘要

Dyes of the general formula are prepared by subjecting a 2-alkyl-, 2-alkylthio-, 2-aralkylthio-, or 2-arylthio-41-alkoxythionaphthene-71 : 61 : 4 : 5-thiazole quaternary salt to condensation reactions known to give symmetrical carbocyanine dyes, e.g. with orthoesters, diarylformamidines, carboxylic acid anhydrides containing at least 4 carbon atoms, glutaconic acid, or C-alkyl S-alkyl (or aryl or aralkyl)-N-phenylthioimides such as an alkylisothioacetanilide. Bis - (41 - methoxy - 3 - methylthionaphtheno-71 : 61 : 4 : 5-thiazole) b -methyltrimethinecyanine p-toluenesulphonate is prepared by heating together 41-methoxy - 2 - methylthionaphtheno - 71 : 61 : 4 : 5-thiazole metho-p-toluenesulphonate, ethyl orthoacetate, and pyridine. Bis - (41 - methoxy - 3 - ethylthionaphtheno-71: 61 : 4 : 5-thiazole)-b -methyltrimethinecyanine p-toluenesulphonate is similarly prepared. 41 - Methoxy - 2 - methylthionaphtheno-71 : 61 : 4 : 5-thiazole metho-p-toluenesulphonate is prepared by heating together 41-methoxy-2-methylthionaphtheno-71 : 61 : 4 : 5-thiazole and methyl p-toluenesulphonate. 41-Methoxy-2-ethylthionaphtheno-71 : 61 : 4 : 5-thiazole metho-p-toluenesulphonate is similarly prepared. Specification 593,025 is referred to.