134447-11-3Relevant articles and documents
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
Neubert, M. E.,Leung, K.,Jirousek, M. R.,Ezenylimba, M. C.,Sabol-Keast, S.,et al.
, p. 21 - 41 (2007/10/02)
The effect of a (CH2)nCO2R' 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 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 escept no C phases were observed.Comparisons of the transition temperatures for these esters with those for Y = R' showed that both small increases or decreases were observed for Y = CO2R'.However, the addition of a spacer methylene group (n = 1 and 2) always gave lower temperatures with the amount of lowering being much greater for n = 2 than n = 1.A comparison of transition temperatures for Y = CO2R', OCOR', COR' and OR' indicated that these temperatures were higher when Y = COR' as expected from dipole moment considerations but were lower when Y = CO2R' than when Y = OCOR', the opposite expected from these considerations.This trend was also observed in the cyclohexane diesters.Transition temperatures were always higher for the esters when Y has an oxygen atom adjacent to the benzene ring.Therefore, esters with Y = O(CH2)nCO2R', n = 1 and 2 were also synthesized.The phenols were prepared by alkylation of 4-benzyloxyphenol with the bromo esters followed by hydrogenolysis.However, these esters showed no mesophases except the cyclohexane diester with n = 2.
