Determination of pKa Values of Some New Triazole Derivatives Using Different Methods

The protonation constant values of 12 new triazole derivatives have been determined by potentiometric and spectrophotometric methods. Potentiometric and spectrophotometric methods were used in ethanol %50 - water %50, dioxan %50 - water %50 and methanol %50 - water %50 mixtures at 25 degrees C with an ionic strength of 0.10 M. The calculation of the stoichiometric protonation constants was carried out using a PKAS computer program. In spectrophotometric method, the electronic absorption spectra of these triazole derivatives at various pH values at 200-400 nm intervals were recorded. The calibration of the electrode system was done potentiometrically by Gran's method. Data were calculated using the linearization method with Henderson-Hasselbach equation. The obtained results are in good accordance with potentiometric values. In addition, these triazole derivatives were studied in non-aqueous media (isopropyl alcohol, t-butyl alcohol, N,N-dimethyl formamide and acetonitrile) by potentiometric method according to half neutralization method. The half neutralization potential values and the corresponding pKa values were determined for all cases. The effect of solvents composition on the stoichiometric protonation constants are discussed.