A quantitative measure of solvent solvophobic effect

Abstract

Gibbs energies of transfer of argon, alkanes, and alkane-like compounds from water to numerous aqueous–organic mixtures and to pure solvents are tabulated. It is shown that these ΔG_t° values can be correlated through a set of equations, where ΔG_t° refers to transfer of a series of solutes from water to a ΔG_t°(to solvent)=MR_T+D given solvent, R_T is a solute parameter, and M and D characterise the solvent. For 20 solutes in 51 solvent systems, 375 ΔG_t° values are thus correlated with a standard deviation of 0.078 kcal mol^–1. The M values in the above equation are then used to define a solvent solvophobic effect so that Sp values are scaled Sp= 1 –M/M(hexadecane) from unity (water) to zero (hexadecane). The Sp values so obtained agree with the qualitative series reported by Sinanoglu and Abdulnur for pure solvents, and are shown to be quantitatively related to h.p.l.c. capacity factors.