Der Pharma Chemica
Journal for Medicinal Chemistry, Pharmaceutical Chemistry, Pharmaceutical Sciences and Computational Chemistry

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Abstract

Synthesis and Study of Thermotropic Mesogenic Homologous Series: p- (p’-nalkoxy benzoyloxy)-m- Chlorophenyl azo-p”- Chlorobenzenes

Author(s): Chauhan. B. C and Doshi. A. V

A mesogenic homologous azoester series is synthesized with a view to understand the effect of laterally substituted functional group on mesogenic characteristics of a molecule. Titled homologous series is synthesized by reacting p-hydroxy- m-chlorophenyl azo -p’-chlorobenzen and corresponding acid chloride of p-n-alkoxy benzoic acid in dry pyridine by established method. Products were purified by alcohol. Mesogenic characteristics commences from its propyl derivative. Propyl to octyl derivatives are only enantiotropic nematic. Smectic property commences from decyl derivative. Decyl, dodecyl, tetradecyl, and hexadecyl derivatives exhibit both smectic and nematic mesophase in enantiotropic manner. Methyl and ethyl derivatives are non-mesogenic. Transition temperatures are observed through an optical polarising microscope with heating stage. Smectic mesophase range is relatively shorter than nematic mesophase range. Series is of middle ordered melting type. The solid-isotropic or solid-smectic (or nematic) and nematic-isotropic transition curves behave in normal manner, except with negligible abnormality in case of some members of the series. Odd-even effect is observed in nematic–isotropic curve upto heptyl/octyl derivatives. The texture of nematic mesophase is threaded type and that of smectic mesophase in case of hexadecyl derivative is of Sm-C type, while, rest of the smectogenic members exhibit smectic mesophase are of the type A as determined from miscibility method. Enthalpy (ΔH) and entropy ( ΔS ) of transition concept discussed qulitatively. Analytical data support the structures of molecules. Thermal stability and mesogenic characteristics are comparable with structurally similar homologous series.


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