Effect of 4-substitution on the thermodynamics of hydration of phenol and the phenoxide anion

Abstract

Enthalpies, entropies, and free energies of sublimation of phenol, 4-bromophenol, 4-formylphenol, and 4-nitrophenol have been evaluated from measurements of the vapour pressures of the solid phenols as a function of temperature. Heats of solution of the phenols in water have been determined calorimetrically and together with solubility data allow calculation of the entropies of solution. Enthalpies, free energies, and entropies of hydration are deduced and are discussed in relation to the effect of 4-substituents on the thermodynamics of ionization of phenol in water. Enthalpies of solution and solvation of the four phenols in methanol have also been measured.