Synthesis, characterization and polymerization of new maleimides containing pendant 1,3,4-oxadiazole moiety

Ahlam Marouf Al-Azzawi and Hib

Abstract

In this work, a series of new polymaleimides having pendant 1, 3, 4-oxadiazole moiety were synthesized. Synthesis of the new polymers was performed by many steps. In the first step, five 2-amino-5-substituted-1,3,4-oxadiazoles were synthesized by oxidative cyclization of substituted semicarbazones under treatment with bromine and anhydrous sodium acetate in glacial acetic acid. The prepared 1, 3, 4-oxadiazoles were introduced in reaction with maleic anhydride in the second step producing five N-[5-substituted-1, 3, 4-oxadiazole-2-yl] maleamic acids and these in turn were dehydrated in the third step by fusion method producing the corresponding N-[5-substituted-1, 3, 4-oxadiazole-2-yl] maleimides. The synthesized maleimides were introduced in the fourth step in free radical polymerization affording the new target polymers. The newly synthesized polymaleimides are expected to possess high thermal stability due to the presence of both imide and 1, 3, 4-oxadiazole cycles in their repeating units.