HIGH CORRELATION BETWEEN HYDROPHOBIC FREE-ENERGY AND MOLECULAR-SURFACE AREA CHARACTERIZED BY ELECTROSTATIC POTENTIAL

For 41 hydrocarbons including paraffins, olefins, acetylenes and aromatics, the solvent accessible surface areas partitioned according to the electrostatic molecular potential levels have been computed and correlated with the hydrophobic free energies derived from their aqueous solubilities. The results indicate that the free energy is a linear function of the areas of two parts of the solvent accessible surface, one of which has an electrostatic potential above - 1 kcal/mol and the other has a potential of - 1 kcal/mol or below. The coefficients of the two parameters are about 25 cal/mol/angstrom 2 and 5 cal/mol/angstrom 2 at 25-degrees-C, respectively, and the multiple correlation coefficient is 0.987.