title: A study of the hydrogen abstraction reactions of C2H radical with CH3CN, C2H5CN, and C3H7CN by dual-level generalized transition state theory.
abstract: The hydrogen abstraction reactions C2H + CH3CN --> products (R1), C2H + CH3CH2CN --> products (R2), and C2H + CH3CH2CH2CN --> products (R3) have been investigated by dual-level generalized transition state theory. Optimized geometries and frequencies of all the stationary points and extra points along the minimum-energy path (MEP) are performed at the BH&H-LYP and MP2 methods with the 6-311G(d, p) basis set, and the energy profiles are further refined at the MC-QCISD level of theory. The rate constants are evaluated using canonical variational transition state theory (CVT) with a small-curvature tunneling correction (SCT) over a wide temperature range 104-2000 K. The calculated CVT/SCT rate constants are in good agreement with the available experimental values. Our calculations show that for reaction R2, the alpha-hydrogen abstraction channel and beta-hydrogen abstraction channel are competitive over the whole temperature range. For reaction R3, the gamma-hydrogen abstraction channel is preferred at lower temperatures, while the contribution of beta-hydrogen abstraction will become more significant with a temperature increase. The branching ratio to the alpha-hydrogen abstraction channel is found negligible over the whole temperature range.
authors: Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023, People's Republic of China.
authors: Zeng-Xia
authors: ZX
authors: Zhao
authors: Jing-Yao
authors: JY
authors: Liu
authors: Li
authors: L
authors: Wang
authors: Hong-Xing
authors: HX
authors: Zhang
authors: Chun-Yuan
authors: CY
authors: Hou
authors: Chia-Chung
authors: CC
authors: Sun