Microwave Synthesis and Antibacterial Activity of 1,4-Bis (5-aryl-1,3,4-oxadiazole-2-yl) Benzene Derivatives from Terephthalic Dihydrazide Obtained Through Aminolysis of PET Bottle Waste

Recycling of waste PET bottles was attempted using aminolytic depolymerization with hydrazine monohydrate in the presence of NiCl2 and MgCl2 as catalysts, under reflux. The reaction was carried out in a domestic microwave oven of 700 W with suitable modification. Terephthalic dihydrazide (TPDH) was obtained in only 10 min as a pure product with 86 % yield as compared to 4 h by conventional heating. Various 1,4-bis(5-aryl-1,3,4-oxadiazole-2-yl) benzene (2a-f) derivatives were prepared from TPDH by treatment with appropriate aromatic acids in the presence of phosphoryl chloride and thionyl chloride, under microwave irradiation, which required only 20 min. The structures of the synthesized compounds were confirmed by FTIR, melting point and NMR. These compounds were found to possess antibacterial activity comparable to commercial products.