Theoretical studies of the reaction of hydroxyl radical with cyclopentane (C₅H₁₀)

Abstract

We performed the first theoretical investigation of the mechanisms and the kinetics of the OH radical reaction with cyclopentane (C₅H₁₀). The geometries and harmonic vibrational frequencies of all of the stationary points are calculated at the BHandHLYP and MP2 levels of theory. The energies of all of the stationary points are refined by using the CCSD(T)/aug-cc-pVTZ calculation and the calculated potential barrier height agrees best with the experimental value. The minimum energy path (MEP) is obtained by the same level of theory and energetic information of the selected points along the MEP is further refined by the CCSD(T) method. The rate constants are evaluated in the temperature range 200–900K by using the conventional transition-state theory (TST), the canonical variational transition-state theory (CVT), and the CVT coupled with the small-curvature tunnelling (SCT) correction (CVT/SCT) method. A general agreement is found among the TST, CVT, and CVT/SCT theories. A comparison between the theoretical and the experimental results is made. The calculated rate constants are in good agreement with the experimental ones in the measured temperature range. The fitted four-parameter expression of the calculated forward CVT/SCT rate constants of the title reaction is

Keywords:

• direct dynamics
• rate constants
• variational transition-state theory
• hydrogen abstraction
• cyclopentane

Acknowledgements

We gratefully thank Professor Donald G. Truhlar for his provision of the POLYRATE 9.6 program. This work is supported by the Natural Science Foundation of China (Grant Nos. 20973076 and 21173096) and Specialized Research Fund for the Doctoral Program of Higher Education (20110061110018).