Synthesis, spectroscopic studies, and antioxidant activities of novel thio/carbohydrazones and bis-isatin derivatives from terephthalaldehyde

Authors: HALİT MUĞLU, HASAN YAKAN, TEMEL KAN BAKIR

Abstract: New bis(isatins-thio/carbohydrazones) based on Schiff bases were prepared from terephthalaldehyde biscarbohydrazone and 5-substituted isatins in the presence of a drop of sulfuric acid under reflux in ethanol. Terephthalaldehyde bis(thio/carbohydrazone) was synthesized by the reaction of (thio)/carbohydrazide and terephthalaldehyde in the presence of a few drops of acetic acid under reflux in ethanol. The structures of these synthesized compounds were determined using IR, $^{1}$H NMR, and $^{13}$C NMR spectroscopy and elemental analysis. The in vitro antioxidant activity of all the compounds was determined by the 1,1-diphenyl-2-picryl hydrazyl (DPPH.) free radical scavenging method. Compound 2 showed the best antioxidant activity.

Keywords: Isatin, carbohydrazone, Schiff bases, DPPH, spectroscopic techniques

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