Theoretical insight into OH- and Cl-initiated oxidation of CF(3)OCH(CF(3))(2) and CF(3)OCF(2)CF(2)H & fate of CF(3)OC(X•)(CF(3))(2) and CF(3)OCF(2)CF(2)X• radicals (X=O, O(2))

In this study, the mechanistic and kinetic analysis for reactions of CF(3)OCH(CF(3))(2) and CF(3)OCF(2)CF(2)H with OH radicals and Cl atoms have been performed at the CCSD(T)//B3LYP/6-311++G(d,p) level. Kinetic isotope effects for reactions CF(3)OCH(CF(3))(2)/CF(3)OCD(CF(3))(2) and CF(3)OCF(2)CF(2)H/CF(3)OCF(2)CF(2)D with OH and Cl were estimated so as to provide the theoretical estimation for future laboratory investigation. All rate constants, computed by canonical variational transition state theory (CVT) with the small-curvature tunneling correction (SCT), are in reasonable agreement with the limited experimental data. Standard enthalpies of formation for the species were also calculated. Atmospheric lifetime and global warming potentials (GWPs) of the reaction species were estimated, the large lifetimes and GWPs show that the environmental impact of them cannot be ignored. The organic nitrates can be produced by the further oxidation of CF(3)OC(•)(CF(3))(2) and CF(3)OCF(2)CF(2)• in the presence of O(2) and NO. The subsequent decomposition pathways of CF(3)OC(O•)(CF(3))(2) and CF(3)OCF(2)CF(2)O• radicals were studied in detail. The derived Arrhenius expressions for the rate coefficients over 230–350 K are: k (T(1) )= 5.00 × 10(−24)T(3.57) exp(−849.73/T), k (T(2) )= 1.79 × 10(−24)T(4.84) exp(−4262.65/T), k(T(3) )= 1.94 × 10(−24) T(4.18) exp(−884.26/T), and k (T(4)) = 9.44 × 10(−28)T(5.25) exp(−913.45/T) cm(3) molecule(−1) s(−1).