Thermodynamics of non-electrolyte transfer between octanol and water

The apparent enthalpy, free energy and entropy of transfer from aqueous buffer (pH 7) to water-saturated octanol were determined for the aliphatic alcohols methanol to octanol using an isoperibol flow-calorimeter. For the higher homologues, a linear relationship between enthalpy and free energy change is found indicating an enthalpy-entropy compensation effect. The thermodynamics of transfer were rationalized in terms of the thermodynamics of solvation in the separate phases, including water itself as a solute. The role of water as a cosolvent in the octanol phase is discussed.Presented at the sixth Italian meeting on Calorimetry and Thermal Analysis (AICAT) held in Naples, December 4–7, 1984.