Atmospheric Chemistry of CF₃C(O)OCH₂CF₃: UV Spectra and Kinetic Data for CF₃C(O)OCH(·)CF₃ and CF₃C(O)OCH(OO·)CF₃ Radicals, and Atmospheric Fate of CF₃C(O)OCH(O·)CF₃ Radicals

Abstract

Pulse radiolysis transient UV absorption spectroscopy was used to study the ultraviolet absorption spectra (230−330 nm) and kinetics of CF3C(O)OCH(·)CF3 and CF3C(O)OCH(OO·)CF3 radicals at 296 K. At 280 nm σ(CF3C(O)OCH(·)CF3) = (1.08 ± 0.13) × 10-18 cm2 molecule-1, at 240 nm σ(CF3C(O)OCH(OO·)CF3) = (2.06 ± 0.24) × 10-18 cm2 molecule-1. Rate constants for the reaction of F atoms with CF3C(O)OCH2CF3, the self-reactions of CF3C(O)OCH(·)CF3 and CF3C(O)OCH(OO·)CF3 radicals, and the reactions of CF3C(O)OCH(OO·)CF3 radicals with NO and NO2 were (1.8 ± 0.2) × 10-12, (1.5 ± 0.2) × 10-11, (7.6 ± 0.9) × 10-12, (1.5 ± 0.2) × 10-11, and (8.5 ± 0.9) × 10-12 cm3 molecule-1 s-1, respectively. The atmospheric fate of CF3C(O)OCH(O·)CF3 radicals was investigated in a FTIR smog chamber. Three loss processes for the CF3C(O)OCH(O·)CF3 radicals were identified at 296 K and 700 Torr total pressure, reaction with O2 to form CF3C(O)OC(O)CF3, α-rearrangement to form CF3C(O)· radicals and CF3C(O)OH, and decomposition via a mechanism which is unclear. In 760 Torr of air at 296 K, 65% of the CF3C(O)OCH(O·)CF3 radicals react with oxygen, 18% undergo α-rearrangement, while the fate of the remaining 17% is unclear.