Abstract
The stoichiometric dissociation constants (pK) of gallic acid were determined in water and several mixed solvents comprising 10–90% (v/v) acetonitrile in water at a temperature of 24.0±0.5°C and an ionic strength of 0.10moldm−3 KCl medium. In this study, the protonation equilibrium values were calculated from potentiometric measurements and the influence of organic solvent composition on the equilibria was correlated with Born electrostatic model and the Kamlet, Abboud and Taft (KAT) solvatochromic parameters of acetonitrile–water mixtures. The pK values obtained increase when the amount of acetonitrile solvent increases in system investigated. The KAT single and multiple correlation analysis suggest that the specific and non-specific solvent interactions including hydrogen-bond donor ability (α), hydrogen-bond acceptor ability (β) and dipolarity/polarizability (π*) are dominating factors which control the protonation equilibria in system under study.
Published Version
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