Free energies of transfer of some single ions from ethylene glycol to its isodielectric mixtures with acetonitrile at 25 °C

Abstract

Free energies of transfer (ΔGt0) of the reference electrolyte Ph4AsBPh4 (Ph = phenyl) from ethylene glycol to its approximately isodielectric mixtures with acetonitrile have been determined at 25 °C from the measurement of the solubilities of KPi, Ph4AsPi, and KBPh (Pi = picrate) in these solvents. Using the assumption [Formula: see text] values for the individual ions K+, Pi−, Ph4As+, and Ph4 s− have been estimated. These, in conjunction with previously determined values of ΔGt0 for MCl (M = Li, Na, K, Rb, Cs, and H), KBr and KI have provided ΔGt0 values for Cl−, Br−, I−, and M+ ions. Ionic ΔGt0's have been interpreted in terms of specific ion–solvent interactions. The contrasting behaviour of ethylene glycol and acetonitrile in ion-solvation is shown to be characteristic of the protic and dipolar aprotic solvent types respectively.