On the kinetic mechanism of CHF2CHF2 and CHF2CF3 with X atoms (XÂ =Â F, Cl) reactions

The dynamical properties of the hydrogen abstraction reactions of CHF2CHF2/CHF2CF3 + X in the temperature range 200-1500 K are investigated theoretically. The minimum energy paths (MEPs) of both reactions are calculated at the MP2/6-311G(d,p) level, and the energies along the MEPs are further refined at the G3(MP2) (single-point) level. With the aid of canonical variational transition state theory including the small-curvature tunneling correction, the rate constants of the title reactions were calculated over a wide temperature range. Agreement between the CVT/SCT rate constants and the experimental values is good. The rate constants may relate with the hardness η of the haloethane molecules.