Quantitative analysis of solvent effects on the keto–enol equilibrium of pentane-2,4-dione in aqueous solutions

Abstract

A quantitative analysis is described for solvent effects on homogeneous chemical equilibria in dilute aqueous solutions in terms of pairwise solute–solute interactions. Solvent effects of a series of monohydric alcohols on the keto–enol tautomeric equilibrium of pentane-2,4-dione (PD) have been measured in order to test the applicability of the new method. Observed medium effects could be successfully accounted for on the basis of contributions of methylene and hydroxy groups. In addition, the dependence of the equilibrium quotient on the concentration of PD has been analysed in terms of cosolvent effects.