Şule Bahçeci,a Haydar Yüksek,b* Zafer Ocak,c Canan Köksal,a Mustafa Özdemirc

aFatih Education Faculty, Karadeniz Technical University, 61335 Trabzon, Turkey
bDepartment of Chemistry, Kafkas University, 36100 Kars, Turkey
cDepartment of Chemistry, Karadeniz Technical University, 61080 Trabzon, Turkey

Abstract
3-Alkyl(Aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) reacted with 3,4-dihydroxy-benzaldehyde to afford the corresponding 3-alkyl(aryl)-4-(3,4-dihydroxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (3). The acetylation and methylation reactions of the latter compounds were investigated, and 4 and 5 type compounds were obtained, respectively. The new compounds were characterized using IR, 1H-NMR, 13C-NMR and UV spectral data. In addition, solutions of the compounds 3a-3e were titrated potentiometrically with tetrabutylammonium hydroxide in three different non-aqueous solvents such as acetonitrile, isopropyl alcohol and N,N-dimethylformamide. The half-neutralization potential values and the corresponding pKa values of these compounds were determined in the solvents described above. Thus, the effects of solvents and molecular structure upon acidity were investigated.
Key words: 4,5-Dihydro-1H-1,2,4-triazol-5-one, Schiff base, methylation, acetylation, acidity, potentiometric titrations.