Effect of intermolecular interactions on the thermodynamic properties of transfer of naphthalene in water-isopropyl alcohol solutions

Standard thermodynamic functions of transfer of naphthalene from water to H2O-isopropyl alcohol (IPA) mixtures have been determined. Standard free energies of transfer for naphthalene showed a complex decreasing tendency with the increasing of x (IPA), and the standard entropy and enthalpy of transfer exhibited a change of double peak curves with x (IPA). This illustrated that the microcosmic structures of a series of mixed solvents of H2O-IPA underwent a variable process from relative order to relative disorder and then from relative disorder to relative order, and back to relative. disorder again, then up to relative order. The results show that there is a relatively ordered structure near x (IPA) = 0.08 in H2O-IPA solutions besides the existence of a clathrate structure in the water-rich region.