HYDROPHOBIC EFFECT AT THE ORIGIN OF THE LOW SOLUBILITY OF INERT SOLIDSUBSTANCES IN HYDROGEN-BONDED SOLVENTS

The new solubility equation derived from the thermodynamics of mobile order in liquids is used to predict the solubility of four solid aliph atic and aromatic hydrocarbons, namely, tricosane, octacosane, bipheny l and pyrene, in nonassociated and hydrogen-bonded solvents. The analy sis of the relative importance of the different terms contributing to the solubility shows that(l) the fluidization of the solute always rep resents a barrier to the solubility, (2) in non-hydrogen-bonded solven ts, the solubility essentially results from the balance of the exchang e entropy correction and the change in the-nonspecific cohesion forces upon mixing, (3) in alcohols or in water, the solubility is mainly de termined by the hydrophobic effect which corresponds to a solute rejec ting effect of the solvent. This effect is responsible for the lower s olubility values of the inert substances in associated solvents with r espect to those in nonassociated solvents.