Rate constants calculation of hydrogen abstraction reactions CH3CHBr + HBr and CH3CBr2 + HBr

Authors

  • Li Wang,

    1. Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, People's Republic of China
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  • Jianxiang Zhao,

    1. Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, People's Republic of China
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  • Hongqing He,

    1. Wuhan Center for Magnetic Resonance, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China
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  • Jinglai Zhang

    Corresponding author
    1. Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, People's Republic of China
    • Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004, People's Republic of China
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Abstract

Dual-level direct dynamics method is used to study the kinetic properties of the hydrogen abstraction reactions of CH3CHBr + HBr → CH3CH2Br + Br (R1) and CH3CBr2 + HBr → CH3CHBr2 + Br (R2). Optimized geometries and frequencies of all the stationary points and extra points along the minimum-energy path are obtained at the MPW1K/6-311+G(d,p), MPW1K/ma-TZVP, and BMK/6-311+G(d,p) levels. Two complexes with energies less than that of the reactants are located in the entrance of each reaction at the MPW1K/6-311+G(d,p) and MPW1K/ma-TZVP levels, respectively. The energy profiles are further refined with the interpolated single-point energies method at the G2M(RCC5)//MPW1K/6-311+G(d,p) level of theory. By the improved canonical variational transition-state theory with the small-curvature tunneling correction (SCT), the rate constants are evaluated over a wide temperature range of 200–2000 K. Our calculations have shown that the radical reactivity decreases from CH3CHBr to CH3CBr2. Finally, the total rate constants are fitted by two modified Arrhenius expression. © 2012 Wiley Periodicals, Inc.

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