Effects of Branching of the Alkyl Chain on the Liquid Crystalline Properties of N-(p-Phenylbenzylidene)-p-Alkoxycarbonylanilines

Abstract

The Liquid crystal behavior of twenty-three N-(p-phenylbenzylidene)-p-alkoxycarbonyl-anilines has been examined by optical microscopy and differential scanning calorimetry in order to study the effects of branching of the alkyl groups. Among the results obtained, the following are particularly of interest: (1) the effect of methyl group(s) on the penultimate carbon of the propyl ester on the nematic thermal stabilities is essentially nil or small, (2) the emergence of a nematic Liquid crystal is achieved by 2-methylation of the purely smectogenic butyl and pentyl esters, and (3) the thermal stability of smectic phase is not always decreased by methylation but is increased in some cases.