Atmospheric chemistry of t-CF3CH = CHCl: products and mechanisms of the gas-phase reactions with chlorine atoms and hydroxyl radicals

作者：Andersen M P Sulbaek^*; Nielsen O J; Hurley M D; Wallington T J

来源：Physical Chemistry Chemical Physics, 2012, 14(5): 1735-1748.

DOI：10.1039/c1cp22925g

FTIR-smog chamber techniques were used to study the products and mechanisms of the Cl atom and OH radical initiated oxidation of trans-3,3,3-trifluoro-1-chloro-propene, t-CF3CH=CHCl, in 700 Torr of air or N-2/O-2 diluent at 296 +/- 2 K. The reactions of Cl atoms and OH radicals with t-CF3CH=CHCl occur via addition to the C=C double bond; chlorine atoms add 15 +/- 5% at the terminal carbon and 85 +/- 5% at the central carbon, OH radicals add approximately 40% at the terminal carbon and 60% at the central carbon. The major products in the Cl atom initiated oxidation of t-CF3CH=CHCl were CF3CHClCHO and CF3C(O)CHCl2, minor products were CF3CHO, HCOCl and CF3COCl. The yields of CF3C(O)CHCl2, CF3CHClCOCl and CF3COCl increased at the expense of CF3CHO, HCOCl and CF3CHClCHO as the O-2 partial pressure was increased over the range 10-700 Torr. Chemical activation plays a significant role in the fate of CF3CH(O)CHCl2 and CF3CClHCHClO radicals. In addition to reaction with O-2 to yield CF3COCl and HO2 the major competing fate of CF3CHClO is Cl elimination to give CF3CHO (not C-C bond scission as previously thought). As part of this study k(Cl + CF3C(O)CHCl2) = (2.3 +/- 0.3) x 10(-14) and k(Cl + CF3CHClCHO) = (7.5 +/- 2.0) x 10 (12) cm (3) molecule (1) s (1) were determined using relative rate techniques. Reaction with OH radicals is the major atmospheric sink for t-CF3CH=CHCl. Chlorine atom elimination giving the enol CF3CH=CHOH appears to be the sole atmospheric fate of the CF3CHCHClOH radicals. The yield of CF3COOH in the atmospheric oxidation of t-CF3CH=CHCl will be negligible (<2%). The results are discussed with respect to the atmospheric chemistry and environmental impact of t-CF3CH=CHCl.

• 出版日期2012