Correlation and prediction of gas–liquid partition coefficients in hexadecane and olive oil

Abstract

A cavity theory of solution has been used to derive an equation for the correlation and prediction of Ostwald solubility coefficients (as log L values) of solutes in hexadecane and olive oil: log L= a + bV+ c(MR)+ dµ² The endoergic work of creating a cavity in the solvent is given by bV, where V is a solute volume, and the exoergic solute–solvent interactions are given by c(MR) and dµ², being dispersion and dipole-induced dipole (or dipole–dipole) effects, respectively; MR and µ are the solute molar refraction and dipole moment. When applied to 84 log L values for a wide variety of solutes in hexadecane, the standard deviation in log L is only 0.18 log units, and for 52 non-acidic solutes in olive oil the corresponding standard deviation is 0.23 log units. Comparison of calculated and observed log L values on olive oil for a number of hydrogen-bond-donor solutes shows that hydrogen bonding from the solute to the basic olive oil is negligible for solute CHCl₃, but contributes about 20% of the total solute–olive oil interaction energy for alcohol solutes, viz. ∼ 2 kcal mol^–1.