A new series of some pyridine condensed oxadiazole derivatives were prepared by reacting pyridine derivative with various aromatic carboxylic acids. In the present work 9 different 2, 5-disubstituted 1, 3, 4 oxadiazole derivatives (3a-i) were synthesized. Pyridine 4-carboxylic acid (Nicotinic acid) is converted into methyl pyridine 4-carboxlate by esterification. Pyridine 4-carboxlate is converted to pyridine 4-carbohydrazide (Isoniazid) by treating with hydrazine hydrate. Pyridine 4-carbohydrazide is converted to 2, 5-disubstituted 1, 3, 4 oxadiazole derivatives by treating with different types of aromatic carboxylic acids in the presence of POCl₃. Confirmation of the chemical structure of the synthesized compounds was substantiated by TLC, IR, ¹H NMR, and MS spectroscopy.

All the synthesized compounds were tested for in-vitro antibacterial (against Escherichia coli, Bacillus subtilis, Staphylococcus aureus) and antifungal activity (against Aspergillus niger). 5e_, 5i_, 5b, 5d showed better inhibition as compared to the standard Ciprofloxacin and 5b, 5d_, 5e & 5i showed good inhibition as compared to the standard Ketokonazole.