SYNTHESIS AND CHARACTERIZATION OF SOME NEW COMPOUNDS DERIVED FROM SEMICARBAZIDES AND 2-AMINO OXADIAZOLE (MONOMERS AND POLYMERS ) AND STUDY THEIR LIQUID CRYSTALLINE PROPERTIES

Abstract

A series of new compounds derived from semicarbazides containing azomethane linkage which found to be liquid crystals.These Schiff's bases resulted from the reaction between substituted semicarbazide [I] and different substituted benzaldehyde in presence of few drops of glacial acetic acid as a catalyst and absolute ethanol as a solvent.These derivatives exhibited thermotropic liquid crystalline properties.This semicarbazide then cyclized to 2-amino oxadiazole which converted to allylic monomers by reacting it with acryloyl and methyl methacryloyl chlorides.These monomers were polymerized free radically with AIBN or benzoyl peroxide as initiator The monomers and its polymers were characterized by IR and H1NMR spectra .These new compounds show mesomorphic properties were discussed with relation to chemical structure of these molecules.The structures of these compounds were characterized by IR, H1NMR spectra for some of them,C.H.N. analysis, melting points and transition temperatures were checked