Theoretical investigation of the enhanced solubility of perfluorobenzene in the supercritical carbon dioxide as a function of temperature and density by Monte Carlo simulation

The absolute free energy of solvation of benzene and perfluorobenzene was measured in supercritical carbon dioxide using the expanded-ensemble method in the context of Monte Carlo (MC) Simulations. The MC calculations were carried out at 12 state points on the solvent phase diagram: (ρr = 0.5, 1.0, 1.5, 2.0; Tr = 1.01, 1.10, and 1.20). These conditions were chosen to address the accurance of specific molecular interactions between CO2 and fluorine. The greater stability of perfluorobenzene observed over all states investigated in this study attributed to the greater solvent accessible surface area and 25-30% increase in the strength of the interaction of this molecule with CO2 in the in-plane part of the first solvation shell, where F atoms exist.

Different shape of the pair interaction energy distributions in the in-plane part of the first solvation shell of benzene and perfluorobenzene may be interpreted as difference in the nature of the interaction of these molecules with CO2 in this region.