Interactions between metal cations and the ionophore lasalocid. Part 10.—Gibbs functions, enthalpies, entropies and volumes for proton–alkali-metal cation exchange in a water–chloroform system

Abstract

Thermodynamic functions for the reaction of lasalocid in a chloroform phase with alkali-metal cations in a water phase have been obtained using various experimental methods. Extraction studies at various pH values afforded the formation constants of the lasalocid salts in such systems. Corresponding enthalpies were obtained from the enthalpies of solution of lasalocid and its salts in methanol and in the chloroform phase using an appropriate thermodynamic cycle. Volumes of reaction were calculated from the densities of the solutions in the water or chloroform phases of the various species involved in the reaction. All these data are discussed in terms of the solvation of the alkali-metal cations in water and of their lasalocid salts in chloroform as related to their structure.