Hybrid Quantum Mechanical/Molecular Mechanics Study of the SN2 Reaction of CH3Cl+OH– in Water
- 11 October 2011
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry A
- Vol. 115 (43), 12047-12052
- https://doi.org/10.1021/jp2076808
Abstract
The S(N)2 mechanism for the reaction of CH(3)Cl + OH(-) in aqueous solution was investigated using combined quantum mechanical and molecular mechanics methodology. We analyzed structures of reactant, transition, and product states along the reaction pathway. The free energy profile was calculated using the multilayered representation with the DFT and CCSD(T) level of theory for the quantum-mechanical description of the reactive region. Our results show that the aqueous environment has a significant impact on the reaction process. We find that solvation energy contribution raises the reaction barrier by ~18.9 kcal/mol and the reaction free energy by ~24.5 kcal/mol. The presence of the solvent also induces perturbations in the electronic structure of the solute leading to an increase of 3.5 kcal/mol for the reaction barrier and a decrease of 5.6 kcal/mol for the reaction free energy, respectively. Combining the results of two previous calculation results on CHCl(3) + OH(-) and CH(2)Cl(2) + OH(-) reactions in water, we demonstrate that increase in the chlorination of the methyl group (from CH(3)Cl to CHCl(3)) is accompanied by the decrease in the free energy reaction barrier, with the CH(3)Cl + OH(-) having the largest barrier among the three reactions.Keywords
This publication has 37 references indexed in Scilit:
- NWChem: A comprehensive and scalable open-source solution for large scale molecular simulationsComputer Physics Communications, 2010
- Combined Quantum Mechanical and Molecular Mechanics Studies of the Electron-Transfer Reactions Involving Carbon Tetrachloride in SolutionThe Journal of Physical Chemistry A, 2008
- Computer Simulations of Enzyme Catalysis: Methods, Progress, and InsightsAnnual Review of Biophysics and Biophysical Chemistry, 2003
- Reaction Paths for Aqueous Decomposition of CCl2The Journal of Physical Chemistry, 1996
- Translational Energy Dependence of Cross Sections for Reactions of OH-(H2O)n with CH3Cl and CH3BrThe Journal of Physical Chemistry, 1995
- Rate constants for the reactions of OH with CH3Cl, CH2Cl2, CHCl3, and CH3BrGeophysical Research Letters, 1994
- Effects of solute concentration and cosolvents on the aqueous activity coefficient of halogenated hydrocarbonsEnvironmental Science & Technology, 1986
- Self-Consistent Equations Including Exchange and Correlation EffectsPhysical Review B, 1965
- Carbon Dihalides as Intermediates in the Basic Hydrolysis of Haloforms. III. Combination of Carbon Dichloride with Halide Ions1Journal of the American Chemical Society, 1954
- Carbon Dichloride as an Intermediate in the Basic Hydrolysis of Chloroform. A Mechanism for Substitution Reactions at a Saturated Carbon Atom1Journal of the American Chemical Society, 1950