The Preparation and Mesomorphic Properties of the Homologous Series of Terephthal - <i>bis- n</i> -Alkylaniline

Abstract

Abstract The C1-C8 and C10 members of the homologous series of terephthal-bis-n-alkylaniline (including TBBA) have been prepared by the condensation of 4-alkylanilines with terephthaldehyde. Synthesis of the anilines was achieved through a Friedel-Crafts acylation of acetanilide followed by a Wolff-Kishner reduction. Interphase transitions between solid, mesomorphic and isotropic phases were studied by hot-stage microscopy and DTA. The nematic phase was observed in the C1-C7 homologs, the smectic A and C phases in the C3-C10 compounds and the smectic H(B) phase in the C2-C10 homologs. An additional smectic phase with a mosaic texture was observed in the C5 homolog and some unexplained anomalies were found in the phase transition behavior of the C2 and C3 compounds. A study of the textures of the smectic C phases as a function of temperature indicated that all these phases have a temperature dependent tilt angle. Relationships between structure and mesomorphic properties as well as with thermodynamic data are discussed and a comparison made with compounds of similar structures reported in the literature.