(1) Department of Analytical Chemistry, University of Barcelona, Diagonal 647, 08028 Barcelona, Spain
Abstract:
The values of the solvatochromic parameters and were determined at 25°C for dioxane-water mixtures from 0 to 100% of dioxane. These values as well as those of the Reichardt polarity parameter ET(30) and the polarity-polarizability * are correlated with acid dissociation constants and other equilibrium constants in solvent mixtures of the same composition. As a general rule, two linear zones with different slopes are obtained, one zone covering water-rich solutions, and the other dioxane-rich solutions. The change in behavior takes place at about 55% (v/v) dioxane for all equilibria studied. A fit of pK to an equation of the multiparametric form proposed by Kamlet and Taft shows in most cases a linear dependence on * alone, in other cases a dependence on * and .