Synthesis, characterization and antioxidant activity investigation of isatin-β-thio/carbohydrazide derivatives

In this thesis;1-Benzylidene-5-(2-oxoindoline-3-ylidene) carbohydrazone, 1-(4-hydroxy benzylidene)-5-(2-oxoindoline-3-ylidene) thiocarbohydrazone, 1-(4-hydroxy benzylidene)-5-(2-oxoindoline-3-ylidene) carbohydrazone, 1-(3-etoxy-4-hydroxy benzylidene)-5-(2-oxoindoline-3-ylidene) carbohydrazone, 1-(4-dimethyl amino benzylidene)-5-(2-oxoindoline-3-ylidene) carbohydrazone, 1-(2-hydroxy benzylidene)-5-(2-oxoindoline-3-ylidene) carbohydrazone, 1-(4-hydroxy-3-methoxy benzylidene)-5-(2-oxoindoline-3-ylidene) carbohydrazone, 1-(3-hydroxy-4-methoxy benzylidene)-5-(2-oxoindoline-3-ylidene) thiocarbohydrazone, 1-(4- hydroxy-3,5-dimethoxy benzylidene)-5-(2-oxoindoline-3-ylidene) carbohydrazone were synthesized by the reaction of isatin-β-thiocarbohydrazones, carbohydrazones and aldehyde derivatives in the presence of acidic in ethanol. The chemical structures of the products were confirmed by 1H NMR, 13C NMR, IR and elemental analysis. Physicochemical properties such as melting point, color and solubility were determined. In vitro antioxidant activity of all compounds was determined by 1,1-Diphenyl-2-Picril Hydrazil (DPPH) free radical scavenging method. All of the synthesized compounds showed lower antioxidant activity than the gallic acid standard and followed the sequence of 2>4>9>7>8>5>3>1>6.