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Improvements in the O-alkylation of 4-substituted phenols with alkyl bromides in the presence of base by using anhydrous conditions has led to better methods for the preparation of 4-substituted alkoxybenzenes in which the substituent is either an aldehyde or a protected functional group. The protected groups can be benzyloxy, acetamido and carboxylic acid methyl ester which are easily converted to hydroxy, amino and acid chloride groups. A mixture of N,N-dimethylformamide and benzene containing molecular sieves and sodium hydroxide as the base along with an azeotropic distillation provides the necessary anhydrous conditions to avoid hydrolysis of the protecting groups. A variety of mesomorphic compounds such as 4,4′-disubstituted phenylbenzoates, phenylthiobenzoates, benzylideneamino (Schiff's bases) compounds and azoxybenzenes in which at least one of the terminal substituents is an alkoxy group can be prepared from these 4-substituted alkoxybenzenes.

We have carried out pressure studies on three pure compounds, viz., di-(4′- n -octyloxyphenyl)-trans-cyclohexane-1, 4-dicarboxylate), p- n-nonyloxybenzoic acid and n-pentyl-4 (4′- n-decyloxybenzylideneamino) cinnamate, each of which exhibits the smectic C phase but the nature of the temperature variation of the tilt angle being different in the three cases. It is found that for all the compounds the smectic C phase is suppressed at high pressures.

The homologous Series of trans-1,4-cycolhexane-di-4′-n-alkoxybenzoates in which the alkyl group is C1-C8, C10, C12, C14 and C16 has been prepared by esterification of trans-1,4-cyclohexanedicarbonyl chloride with 4-alkoxyphenols. Mesomorphic properties and phase transitions have been determined using polarizing hot-stage microscopy and DSC. A comparison of the data for this series with those for the analogous terephthalic acid diesters gives some insight into the effect of a cyclohexane ring on mesomorphic propertries. Relationships between thermal and x-ray data and structures are discussed.