Synthesis and Antioxidant Activities of Some New 4-(4-Hydroxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-one Derivatives with Their Acidic Properties

摘要

Fourteen new compounds having 4,5-dihydro-1H-1,2,4-triazol-5-one ring,namely six new 3-alkyl(aryl)-4-(4-hydroxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones(3),four new 1-acetyl-3-alkyl(aryl)-4-(4-acetyloxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones(4),two new l-methyl-3-alkyl-4-(4-methoxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones(5)and two new 3-alkyl(aryl)-4-[4-(p-tolylsuIfonyl)-oxybenzyIidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-ones(6),were synthesized.The structures of the newly synthesized compounds were determined by elemental analysis as well as IR,~1H NMR,~(13)C NMR and UV spectral data and their antioxidant activities,except compounds 3e and 4f,were investigated.In addition,compounds 3a-f were titrated potentiometrically with tetrabutylammonium hydroxide in three non-aqueous solvents such as isopropyl alcohol,t-butyl alcohol and N,N-dimethyl formamide.The half-neutralization potential values and the corresponding pK_a values were determined for all the cases.