Theoretical study of a reaction mechanism of tropospheric interest: CH3CH2F + OH

Dual-level electronic structure calculation has been performed to investigate the mechanism and all possible channels of OH radical reaction with CH3CH2F. Geometries and frequencies are computed at the B3LYP/6-311G(d,p) level of theory for all stationary points and complexes and transition states are located. Potential energy surfaces are constructed at the PMP2/cc-pVTZ//B3LYP/6-311G(d,p) level + ZPE correction. Four types of reaction channels are identified: hydrogen abstraction, fluorine abstraction and attack on carbon atom along or perpendicular to the C - C bond axis. Hydrogen abstraction channels have lower barriers and are more exothermic, while out-of-plane beta - H abstraction with the lowest barrier is competitive with alpha - H abstraction. Due to the high energy barrier, contributions of non-H abstraction channels are excluded. The influence of hydrogen bonding interaction is clearly observed in the barrier heights.