Two-dimensional free-energy surface on the exchange reaction of alkyl chloride/chloride using the QM/MM-MC method

Journal Article · Wed Dec 05 00:00:00 EST 2007 · Physical Chemistry Chemical Physics. PCCP, 10:844-849

DOI:https://doi.org/10.1039/b712565h· OSTI ID:944900

Ohisa, M; Yamataka, H; Dupuis, Michel; Aida, Misako

Two-dimensional free-energy surfaces are calculated for alkyl chloride/chloride exchange/inversion reactions: Cl- + RCl (R = Me and t-Bu) surrounded by one hundred H2O molecules as a model of solvent. The methodology of free-energy calculation by perturbation theory based on a mixed-Hamiltonian model (QM/MM) combined with Monte Carlo sampling of the solvent configurations was used to obtain the changes in solvation free energy. We devised a special procedure to analyze the two-dimensional free-energy surfaces to gain unique insight into the differences in the reaction mechanisms between the two systems. The inversion reaction path for R = t-Bu on the free-energy surface is found to proceed in an asynchronous way within a concerted framework via the ion-pair region. This is in contrast to the R = Me system that proceeds as a typical SN2 reaction. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 944900
• Report Number(s): PNNL-SA-59499; KC0301020; TRN: US200902%%1082
• Journal Information: Physical Chemistry Chemical Physics. PCCP, 10:844-849, Vol. 10
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
FREE ENERGY
PERTURBATION THEORY
CHEMICAL REACTION KINETICS
SOLVATION
TWO-DIMENSIONAL CALCULATIONS
CHLORIDES
METHYL CHLORIDE
CHLORINATED ALIPHATIC HYDROCARBONS
MIXED HAMILTONIAN MODEL
SOLVATED EXCITED-STATES
AQUEOUS-SOLUTION
ELECTRONIC-STRUCTURE
SN2 REACTION
ION-PAIRS
WATER
POTENTIALS
HYDRATION
ATOM