Theoretical Studies on Mechanism and Kinetics of the Hydrogen-Abstraction Reaction of CF3CH2CHO with OH Radicals

The hydrogen abstraction reaction of CF₃CH₂CHO + OH has been studied theoretically by dual-level direct dynamics method. Two stable conformers, trans- and cis- CF₃CH₂CHO , have been located, and there are four distinct OH hydrogen-abstraction channels from t- CF₃CH₂CHO and two channels from c- CF₃CH₂CHO . The required potential energy surface information for the kinetic calculation was obtained at the MCG3-MPWB//M06-2X/aug-cc-pVDZ level. The rate constants, which were calculated using improved canonical transitionstate theory with small-curvature tunneling correction (ICVT/SCT) were fitted by a four-parameter Arrhenius equation. It is shown that the reaction proceeds predominantly via the H-abstraction from the -CHO group over the temperature range 200-2000 K. The calculated rate constants were in good agreement with the experimental data between 263 and 358 K.