Molecular Thermodynamics of Methane Solvation in tert-Butanol-Water Mixtures

Maeng-Eun Lee; Nico F A Van der Vegt

doi:10.1021/ct600226h

Molecular Thermodynamics of Methane Solvation in tert-Butanol-Water Mixtures

J Chem Theory Comput. 2007 Jan;3(1):194-200. doi: 10.1021/ct600226h.

Authors

Maeng-Eun Lee¹, Nico F A Van der Vegt¹

Affiliation

¹ Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.

PMID: 26627164
DOI: 10.1021/ct600226h

Abstract

We studied solvation structure and thermodynamics of methane in mixtures of tert-butanol and water using computer simulations. We show that for alcohol mole fractions below 20%, methane is preferentially solvated by hydrated alcohol clusters. Because methane expels water molecules from these clusters, a large endothermic solvent reorganization enthalpy occurs. This process is responsible for the experimentally observed maximum of the heat of methane solvation close to 5% alcohol in the mixture and contributes to a positive entropy change relative to solvation in pure water. Because the structural solvent reorganization enthalpy is enthalpy-entropy compensating, the methane solvation free energy is a smoothly varying function of the alcohol/water solution composition.