Synthesis And Biological Evaluation Of Some Thiadiazole Derivatives And Validation By UV Spectrophotometric Method

Abstract

In the present research work, the 1,3,4-Thiadiazole nucleolus were designed to synthesize new derivatives by simple, economic and efficient method as given in Scheme I. Substituted diacylhydrazines were synthesized by procedure as followed. To the stirred suspension of substituted salicylic hydrazine [30,31] (1 mol) in 15 ml toluene, 0.96 g of methyl sulphonic acid was added at the right time. The mixture was stirred for 10 min, afterwards 1 mol of substituted benzoyl chloride was added. Stirring continued for 3 h to get the product. Then 2,5-disubstituted-1,3,4-thiadiazole derivatives (4a-f) were synthesized by procedure as followed. Diacylhydrazines (0.1 mol) were allowed to react with sulphur source (Lawesson s reagent) which include thionation of the carbonyl group followed by cyclization with loss of H2S. The reaction mixture was refluxed for 3 h to get the product. Different Schiff bases were synthesized by dissolving 0.01 mol of the product obtained earlier in last step in 30 ml of ethanol containing few drops of glacial acetic acid. The appropriate aromatic aldehyde was added and reaction mixture was refluxed for 5 h at 70°C to get the final products. Purity of all the synthesized derivatives was assured by TLC and almost sharp melting point. All synthesized 1,3,4-thiadiazole derivatives were subjected to combustion analysis which supports the purity of the desired synthesized derivatives. Structures of the derivatives were determined and confirmed by Infrared spectroscopy (IR) and Nuclear magnetic resonance (1H NMR). All the synthesized derivatives were tested for their toxicity, antimicrobial activity, antioxidant activity and anticonvulsant activity. QSAR study of the synthesized compounds was carried out using VlifeMDS software. This study aimed to elucidate structural features of 1,3,4-thiadiazole derivatives required for antioxidant activity and to obtain predictive two dimensional QSAR (2D QSAR) models. Among all the synthesized derivatives, 10e exhibited comparable biological activities. Hence sim