The Effect of Carbonyl Containing Terminal Chains on Mesomorphic Properties in 4,4′- Disubstituted Phenylbenzoates and Phenylthiobenzoates. 4. Phenylbenzoates Containing A (CH2)nCO2R'Group (n = 0–2) on the Phenolic End

Abstract

Abstract The effect of a (CH2),CO2R' group on the mesomorphic properties of the esters where X= alkyl or alkoxy, Y=(CH2)nCO2R'(R'=C7 and C9) and n = 0–2 has been studied by synthesizing these esters and determining their mesomorphic properties by hot-stage polarizing microscopy. The starting phenols were prepared by esterification of hydroxy protected 4-hydroxybenzoic, phenylacetic or phenylpropionic acids. Both the benzyl and methoxycarbonyl protecting groups were tried with the latter giving higher yields when n = 0 because of better solubility of the protected acid. No mesophases were observed in the esters when n = 1, nematic and smectic A phases occurred when n = 2 and smectic A and C phases when n = 0. A few 1,4-cyclohexane diesters were also prepared using these phenols, The mesomorphic properties of these esters followed the same trend observed in the phenylbenzoates except no C phases were observed. Comparisons of the transition temperatures for these esters with those for Y=R' showed that both s...