Atmospheric Chemistry of CH₂BrCl, CHBrCl₂, CHBr₂Cl, CF₃CHBrCl, and CBr₂Cl₂

Relative-rate methods were used to measure the following rate constants at 296 K in 700 Torr of N 2, O 2, or air diluent (all cm 3 molecule -1 s -1 ): k (OH + CHBrCl 2 ) = (1.2 ± 0.3) × 10 -13, k (OH + CH 2 BrCl) = (1.2 ± 0.3) × 10 -13, k (Cl + CHBr 2 Cl) = (2.2 ± 0.6) × 10 -13, k (Cl + CBr 2 Cl 2 ) = (1.8 ± 0.4) × 10 -13, k (Cl + CBrCl 3 ) = (7.1 ± 0.9) × 10 -14, and k (Cl + CF 3 CHBrCl) = (2.0 ± 0.3) × 10 -14 . Over the temperature range 217−296 K, k (Cl + CHBrCl 2 ) = (2.6 ± 0.4) × 10 -12 exp(−852 ± 76/ T ) and k (Cl + CH 2 BrCl) = (1.2 ± 0.2) × 10 -11 exp(−1000 ± 82/ T ) cm 3 molecule -1 s -1 were found. The UV absorption spectra of CHBrCl 2, CF 3 CHBrCl, and CHBr 2 Cl were measured at temperatures between 223 and 298 K over the range 210−320 nm. The products of Cl-atom-initiated oxidation of CHBrCl 2, CBr 2 Cl 2, CHBr 2 Cl, and CF 3 CHBrCl were determined using FTIR smog-chamber techniques. Reaction of Cl atoms with CHBrCl 2, CHBr 2 Cl, and CF 3 CHBrCl proceeds via hydrogen abstraction. Reaction of Cl atoms with CBr 2 Cl 2 and CBrCl 3 occurs via bromine abstraction. Product studies of the Cl-initiated oxidation of CHBrCl 2 and CBr 2 Cl 2 conducted with, and without, added NO showed strong evidence for the production of chemically activated alkoxy radicals in the reaction of CBrCl 2 O 2 radicals with NO. These results are discussed with respect to the atmospheric chemistry of CH 2 BrCl, CHBrCl 2, CHBr 2 Cl, CBr 2 Cl 2, CF 3 CHBrCl, and other brominated organic compounds.