Estimation of Water−Organic Interfacial Tensions. A Linear Free Energy Relationship Analysis of Interfacial Adhesion

Abstract

The work of adhesion between water and a series of immiscible organic liquids has been found to obey a linear solvation free energy relationship (LSER) on the basis of solute parameters for the organic compound. This relationship, together with the surface tensions of water and of the pure organic liquids, allows reasonably accurate estimation of the corresponding interfacial tensions and provides insight into the nature of intermolecular forces at the water−organic interface. Furthermore, the similarity of this multiparametric LSER to that for partitioning of organic solutes between water and the gas phase (log LW) leads to a much simpler two-parameter relationship. Estimation of the interfacial tension with this latter relationship requires a knowledge of only two parameters, log LW and the surface tension of the pure organic liquid. Since reasonably accurate group contribution methods are available for estimating both log LW and surface tensions from molecular structure, this result provides a novel approach for a priori estimation of the water−organic interfacial tension directly from the chemical structure of the organic compound itself.