Abstract A series of new 1,3,5-tri-{4-[(3-alkyl/aryl-4,5-dihydro-1H-1,2,4-triazol-5-one-4-yl)-azomethin]-phenoxycarbonyl} benzenes (4) were obtained from the reactions of 3-alkyl/aryl-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) with 1,3,5-tri-(4-formylphenoxycarbonyl)-benzene (1) and characterized by IR, 1H-NMR and 13C-NMR spectral data. In addition, to investigate the effects of solvents and molecular structure upon acidity, the new nine compounds 4 were titrated potentiometrically with tetrabutylammonium hydroxide in four non-aqueous solvents (isopropyl alcohol, tert-butyl alcohol, N,N-dimethylformamide and acetone). The half-neutralization potential values and the corresponding pKa values were determined for all cases.
Keywords: 4,5-Dihydro-1H-1,2,4-triazol-5-one, Schiff base, Syntheses, Acidity, Potentiometric titration, pKa.