SOLVENT EFFECTS ON CHEMICAL PROCESSES .5. HYDROPHOBIC AND SOLVATION EFFECTS ON THE SOLUBILITIES OF SUBSTITUTED BIPHENYLS IN METHANOL-WATER MIXTURES

A phenomenological model that permits solvent effects to be separated into general medium effects (the solvophobic effect) and solvation eff ects is applied to the solubility of a series of biphenyl compounds in methanol/water mixtures. The parameters of the model (gA, K1, and K2, K1 and K2 are equilibrium constants for solvation and gA describes th e general medium contribution) were evaluated from the nonlinear regre ssion of the model equation to the data. It was found that the surface tension curvature factor (g) was 0.37, that A represents the hydropho bic (nonpolar) surface area of the solute molecule, and that K1 and K2 were 2.53 and 1.77 (means for solutes in methanol/water), respectivel y. These results permit solvent effects on solubility in methanol/wate r to be predicted and they refine the interpretation of the solvent ef fect model.