Rate constants calculation of hydrogen abstraction reactions CH3CHBr + HBr and CH3CBr2 + HBr. Issue 7 (7th April 2012)

• Record Type: Journal Article
• Authors: Wang, Li; Zhao, Jianxiang; He, Hongqing; Zhang, Jinglai
• Is Part Of: International journal of quantum chemistry. Volume 113:Issue 7(2013:Apr. 05)
• Page Start: 997
• Page End: 1002
• Publication Date: 2012-04-07
• Subjects: Quantum chemistry -- Periodicals; 541.28
• DOI: 10.1002/qua.24076
• Languages: English
• ISSNs: 0020-7608

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>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.</p> </abstract>