Synthesis and acidic properties of some new potential biologically active 4-acylamino-4,5-dihydro-1H-1,2,4-triazol-5-one derivatives

Abstract

3-Alkyl(aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones 2 react with acyl halides such as chloroacetyl chloride, dichloroacetyl chloride and isobutyryl chloride to give the corresponding 3-alkyl(aryl)-4-chloroacetylamino-4,5- dihydro-1H-1,2,4-triazol-5-ones 3, 3-alkyl(aryl)-4-(dichloroacetylamino)-4,5- dihydro-1H-1,2,4-triazol-5-ones 4 and 3-alkyl(aryl)-4-isobutyrylamino-4,5- dihydro-1H-1,2,4-triazol-5-ones 5, respectively. The newly synthesized compounds have been characterized by elemental analyses, IR, 1H NMR, 13C NMR and UV spectral data. In addition, all ten new compounds are titrated potentiometrically with tetrabutylammonium hydroxide in four different non-aqueous solvents such as isopropyl alcohol, tert-butyl alcohol, acetonitrile and N,N-dimethylformamide. The half neutralization potential values and the corresponding pKa values have been determined for all the cases. Thus, the effects of solvents and molecular structure upon acidity are investigated.