Atmospheric Chemistry of CF₃CH₂OCH₂CF₃:  UV Spectra and Kinetic Data for CF₃CH(•)OCH₂CF₃ and CF₃CH(OO•)OCH₂CF₃ Radicals and Atmospheric Fate of CF₃CH(O•)OCH₂CF₃ Radicals

Abstract

Pulse radiolysis transient UV absorption spectroscopy was used to study the ultraviolet absorption spectra (220−320 nm) and kinetics of CF3CH(•)OCH2CF3 and CF3CH(OO•)OCH2CF3 radicals at 296 K. At 230 nm σ(CF3CH(•)OCH2CF3) = (1.95 ± 0.24) × 10-18 and σ(CF3CH(OO•)OCH2CF3) = (4.40 ± 0.51) × 10-18 cm2 molecule-1. Rate constants for the reaction of F atoms with CF3CH2OCH2CF3, the self-reactions of CF3CH(•)OCH2CF3 and CF3CH(OO•)OCH2CF3 radicals, the association reaction of CF3CH(•)OCH2CF3 radicals with O2, and the reactions of CF3CH(OO•)OCH2CF3 radicals with NO and NO2 were (1.5 ± 0.7) × 10-11, (2.6 ± 0.4) × 10-11, (5.4 ± 0.7) × 10-12 (uncorrected for possible secondary chemistry), (2.3 ± 0.3) × 10-12, (1.45 ± 0.4) × 10-11, and (8.4 ± 0.8) × 10-12 cm3 molecule-1 s-1, respectively. Using an FTIR technique, rate constants for the reaction of Cl atoms with CF3CH2OCH2CF3 and CF3C(O)OCH2CF3 were determined to be (7.1 ± 0.9) × 10-13 and (9.4 ± 1.3) × 10-16 cm3 molecule-1 s-1. Finally, it was determined that the atmospheric fate of CF3CH(O•)OCH2CF3 radicals is decomposition via C−C bond scission to give CF3 radicals and 2,2,2-trifluoroethyl formate (CF3CH2OCHO) which occurs at a rate of approximately 7 × 105 s-1. The results are discussed with respect to the atmospheric chemistry of CF3CH2OCH2CF3 and analogous compounds.