ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
A Monte Carlo simulation of a solution of 1,2-dichloroethane in methyl chloride has been performed in the NPT ensemble. The solution serves as a model to study the differential solvation of the gauche and anti conformers of a polar solute in a polar solvent. The expected conformational change induced by the solvation in favor of the gauche conformer is well reproduced in the simulation. To explain it, the r−12, r−6, and r−1 contributions of the intermolecular potential functions (TIPS format) to the solute–solvent and solvent–solvent energies have been recorded during the simulation. The mean r−1 contributions are computed to be less than one-third of the sum of the r−12 and r−6 contributions; however, the computed difference of 2±0.5 kcal/mol between the gauche and anti solute–solvent mean energy is totally accounted for by the difference in the r−1 contributions. The analysis of the r−1 energy pair distribution shows that the main part of this difference comes from changes in the interaction of the solute with the nearest solvent neighbors. The gauche conformer shows at one and the same time more attractive and more repulsive interactions than the anti conformer. When the pure liquid, the anti and gauche solutions are compared, it is found that the solvent molecules experience, on the mean, nearly the same solvent–solvent interactions in the three cases.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.449213
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