Abstract
We present a theoretical study of the hydrogen abstraction reaction from CH3CHF2 by the HOOO radical. Two different reactive sites of 1,1-difluoroethane molecule, CH3 and CHF2 groups have been investigated, and results confirm that the CHF2 group is a highly reactive site. In this study, the geometries and harmonic vibrational frequencies of all stationary points are calculated at the MPW1K/6-31+G(d,p) and BHandHLYP/6-31+G(d,p) levels of theory. The minimum energy paths (MEPs) are obtained at the MPW1K/6-31+G(d,p) level of theory. To refine the energies along the MEPs of each channel, single-point energy calculations are performed by CCSD/cc-pVTZ method. The rate constants are evaluated with the conventional transition-state theory (TST), the canonical variational transition-state theory (CVT), the microcanonical variational transition-state theory (μVT), the CVT coupled with the small-curvature tunneling (SCT) correction (CVT/SCT), and the μVT coupled with the Eckart tunneling correction (μVT/Eckart) based on the ab initio calculations in the temperature range of 200–3000K. The fitted three-parameter Arrhenius expressions of the calculated CVT/SCT and μVT/Eckart rate constants of the H abstraction from CHF2 group are kCVT/SCT(T)=2.89×10−19T0.75e(−10964.0/T) and kμVT/Eckart(T)=2.68×10−13T−0.70e(−12302.2/T), respectively. The fitted three-parameter Arrhenius expressions of the calculated CVT/SCT and μVT/Eckart rate constants of the H abstraction from CH3 group are kCVT/SCT(T)=1.40×10−19T1.03e(−12271.6/T) and kμVT/Eckart(T)=1.18×10−17T0.61e(−13159.7/T), respectively.
Published Version
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