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Hydrogen abstraction reactions of OH radicals with CH3CH2CH2Cl and CH3CHClCH3: A mechanistic and kinetic study

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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  • Yanjie Li,

    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

The hydrogen abstraction reactions of OH radicals with CH3CH2CH2Cl (R1) and CH3CHClCH3 (R2) have been investigated theoretically by a dual-level direct dynamics method. The optimized geometries and frequencies of the stationary points are calculated at the B3LYP/6-311G(d,p) level. To improve the reaction enthalpy and potential barrier of each reaction channel, the single point energy calculation is performed by the BMC-CCSD method. Using canonical variational transition-state theory (CVT) with the small-curvature tunneling correction, the rate constants are evaluated over a wide temperature range of 200–2000 K at the BMC-CCSD//B3LYP/6-311G(d,p) level. For the reaction channels with the negative barrier heights, the rate constants are calculated by using the CVT. The calculated total rate constants are consistent with available experimental data. The results show that at lower temperatures, the tunneling correction has an important contribution in the calculation of rate constants for all the reaction channels with the positive barrier heights, while the variational effect is found negligible for some reaction channels. For reactions OH radicals with CH3CH2CH2Cl (R1) and CH3CHClCH3 (R2), the channels of H-abstraction from –CH2– and –CHCl groups are the major reaction channels, respectively, at lower temperatures. With temperature increasing, contributions from other channels should be taken into account. Finally, the total rate constants are fitted by two models, i.e., three-parameter and four-parameter expressions. The enthalpies of formation of the species CH3CHClCH2, CH3CHCH2Cl, and CH2CH2CH2Cl are evaluated by isodesmic reactions. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011

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