ATMOSPHERIC CHEMISTRY OF CH2BRCL, CHBRCL2, CHBR2CL, CF3CHBRCL, AND CBR2CL2

Relative-rate methods were used to measure the following rate constant s at 296 K in 700 Torr of N-2, O-2, or air diluent (all cm(3) molecule (-1) s(-1)): K(OH + CHBrCl2) = (1.2 +/- 0.3) x 10(-13), k(OH + CH2BrCl ) = (1.2 +/- 0.3) x 10(-13), k(Cl + CHBr2Cl) = (2.2 +/- 0.6) x 10(-13) , k(Cl + CBr2Cl2) = (1.8 +/- 0.4) x 10(-13), k(CI + CBrCl3) = (7.1 +/- 0.9) x 10(-14), and k(Cl + CF3CHBrCl) = (2.0 +/- 0.3) x 10(-14). Over the temperature range 217-296 k(Cl + CHBrCl2) = (2.6 +/- 0.4) x 10(-1 2) exp(-852 +/- 76/T) and k(Cl + CH2BrCl) = (1.2 +/- 0.2) x 10(-11) ex p(-1000 +/- 82/T) cm(3) molecule(-1) s(-1) were found. The UV absorpti on spectra of CHBrCl2, CF3CHBrCl, and CHBr2Cl were measured at tempera tures between 223 and 298 K over the range 210-320 nm, The products of Cl-atom-initiated oxidation of CHBrCl2, CBr2Cl2 CHBr2Cl, and CF3CHBrC l were determined using FTIR smog-chamber techniques. Reaction of Cl a toms with CHBrCl2, CHBr2Cl, and CF3CHBrCl proceeds via hydrogen abstra ction. Reaction of Cl atoms with CHBr2Cl2 and CBrCl3 occurs via bromin e abstraction. Product studies of the Cl-initiated oxidation of CHBrCl 2 and CBr2Cl2 conducted with, and without, added NO showed strong evid ence for the production of chemically activated alkoxy radicals in the reaction of CBrCl2O2 radicals with NO. These results are discussed wi th respect to the atmospheric chemistry of CH2BrCl, CHBrCl2, CHBr2Cl, CBr2Cl2, CF3CHBrCl, and other brominated organic compounds.