<b>Determination of protonation constants of some 3-alkyl(aryl)-4-(<i>p</i>-t-butyl(benzyl/benzyliden)amino)-4,5-dihydro-1<i>H</i>-1,2,4-triazole-5-one derivatives in ethanol–water mixtures</b>

Abstract

ABSTRACT ABSTRACT. Stoichiometric protonation constants of some 3-alkyl(aryl)-4-(p-t-butyl(benzyl/benzyliden)amino)-4,5-dihydro-1H-1,2,4-triazole-5-one derivatives were determined potentiometrically in 50% (v/v) ethanol-water mixtures at 25 o C with an ionic strength of 0.10 M. The calculation of the stoichiometric protonation constants was carried out using a PKAS computer program. The effect of solvents composition on the stoichiometric protonation constants are discussed. KEY WORDS KEY WORDS KEY WORDS

Solvent Effects on the Dissociation Constants of Hydroxyflavones in Organic–Water Mixtures. Determination of the Thermodynamic pKa Values by UV–Visible Spectroscopy and DFT Calculations

“…Then, from the equilibrium constant of this reaction (eq ) the known Henderson–Hasselbach equation can be obtained. This equation is very useful in the determination of p K a values ,− and it can be formulated in the following way pH W S = normalp K normala W S + log nobreak0em.25em⁡ false( A − A normala false) false( A normalb − A false) where A a and A b are the absorbance of the neutral (AH) and the ionized (A – ) form measured in HCl and NaOH solutions, respectively, A is the absorbance due to the presence of both A – and AH in the buffer solutions, and W S p K a is the apparent acidity constant.…”