Quantum chemical study of the mechanism for OH-initiated atmospheric oxidation reaction of (Z)-CF3CFCHF

The mechanism and products of the reaction of (Z)-CF3CFCHF with OH radical in the absence and presence of O2/NO have been elucidated by performing high-level quantum chemistry calculations. The geometries of the reactants, intermediates, transition states, and products are optimized at the B3LYP/6-311++G(d,p) level, and their single point energies are refined at the CBS-QB3 level. Energies for several species are also recalculated at the G3 level. The calculations indicate that the reaction predominantly proceeds via the addition of OH radical to the double bond rather than the direct abstractions of the H and F atoms in (Z)-CF3CFCHF. The nascent adducts CF3CFC(OH)HF (IM1) and CF3C(OH)FCHF (IM2) can either undergo subsequent isomerization and dissociation reactions or further react with O2/NO. The theoretical results show that the major products are HC(O)F and CF3C(O)F in both the absence and presence of O2/NO, which are in good agreement with the experimental finding.