THE HYDROPHOBIC EFFECT - 2 - RELATIVE IMPORTANCE OF THE HYDROPHOBIC EFFECT ON THE SOLUBILITY OF HYDROPHOBES AND PHARMACEUTICALS IN H-BONDEDSOLVENTS

The quantitative development of the nonergodic mobile order thermodyna mics involving the new interpretation of the hydrophobic effect leads to a general solubility equation. This equation is applied to predict the aqueous and alcohol solubility of chemicals ranging from nonpolar or slightly polar with no H-bonding capacity to polyfunctional polar c ompounds including pharmaceuticals. The analysis of the relative impor tance of the contributions involved in the solubility model [i.e., the fluidization of the solute (for solids), the correction for the mixin g entropy, the change of the nonspecific cohesion forces, and the form ation of solvent-solvent (hydrophobic effect), solute-solute, and solu te-solvent H-bonds] unambiguously demonstrates that the hydrophobic ef fect is essential for predicting the aqueous or alcohol solubility of any substance in general, and of nonpolar compounds in particular. The difference between the origin of the solubility of hydrocarbons in wa ter and of water in hydrocarbons is furthermore presented. In both cas es, the quasilinear solubility dependence on the molar volume of the h ydrocarbon is of an entropic nature.