Synthesis, characterization and antioxidant activities of Shiff bases containing isatin and thiocarbohydrazone

In this thesis, seven new Schiff bases were prepared from monothiocarbohydrazones and 5-chloro isatin. The monothiocarbohydrazones were synthesized in the presence of ethanol under reflux with the reaction thiocarbohydrazide and substituted aldehydes. The reaction of synthesized benzothiocarbohydrazone, 4-hydroxy benzothiocarbohydrazone, 3-ethoxy-4-hydroxyl benzothiocarbohydrazone, 3,5-dimethoxy-4-hydroxyl benzothiocarbohydrazone and 4-N,N,dimethly benzothiocarbohydrazone with 5-chloro isatin in acidic medium under reflux with N1- (5-Chloro-2-oxoindolin-3-ylidene) Shiff bases were obtained. 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. Antioxidant activities of molecules and standard used gallic acid> 3,5-dimethoxy-4-hydroxyl benzothiocarbohydrazone> 3-ethoxy-4-hydroxyl benzothiocarbohydrazone> 4-hydroxy benzothiocarbohydrazone> benzothiocarbohydrazone> N1- (5-chloro-2-oxoindolin-3-ylidene) ) 4-N,N, dimethly benzothiocarbohydrazone> N1- (5-chloro-2-oxoindolin-3-ylidene) 3, ethoxy-4-hydroxyl benzothiocarbohydrazone> 4-N,N, dimethly benzothiocarbohydrazone> N1- (5-chloro-) 2-oxoindolin-3-ylidene) 3,5-dimethoxy-4-hydroxyl benzothiocarbohydrazone> N1- (5-chloro-2-oxoindolin-3-ylidene) 4, hydroxy benzothiocarbohydrazone> N1- (5-chloro-2-oxoindoline- 3-ylidene) benzothiocarbohydrazone. Key Words: N1-(5-chloro-2-oxoindolin-3-ylidene) benzothiocarbohydrazone, Antioxidant Activity, DPPH method, NMR spectroscopy.