Synthesis and Study of a New Ester Homologous Series: Ethyl-p-(p/-n-alkoxy Cinnamoyloxy)Cinnamates

Patel R.B.a; Doshi A. V.

Abstract

Synthesis and Study of a New Ester Homologous Series: Ethyl-p-(p/-n-alkoxy Cinnamoyloxy)Cinnamates

Author(s): Patel R.B.a and Doshi A. V.*

An ester homologous series entitled Ethyl-p-[p/-n-alkoxy cinnamoyloxy] cinnamates is synthesized and studied for liquid crystal behavior and its correlation with molecular structure. Methyl to n-pentyl homologues are non-liquid crystal while, n-hexyl homologue to n-octyl homologue n-decyl, n-dodecyl, n-tetradecyl and n-hexadecyl homologues exhibit liquid crystal properties especially of enatiotropic nematogenic character, even in the monotropic condition. Transition and melting temperatures (Table-1) are determined by hot stage polarizing microscope. A phase diagram (Figure-I) is obtained by plotting transition temperatures ( Table- 1) versus number of carbon atoms in n-alkyl chain of left n-alkoxy terminal. Solid-isotropic / nematic transition curve follows zigzag path of rising and falling with overall descending tendency as series is ascended in normal manner. Nematic-isotropic transition curve initially falls from n-hexyl homologue to n-decyl homologue in normal manner and passes through minima at decyl derivative but rises abnormally as series is ascended upto last homologue of series. The texture of the nematogenic mesophase is of threaded type. Analytical data support the structures of the molecules. Nematogenic mesophase length is relatively short with absence of smectic mesophase. Mesomorphic properties are compared with structurally similar homologous series.

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