Atmospheric chemistry of ()- and ()-1,2-dichloroethene: kinetics and mechanisms of the reactions with Cl atoms, OH radicals, and O.

Smog chambers interfaced with FT-IR detection were used to investigate the kinetics and mechanisms of the Cl atom, OH radical, and O initiated oxidation of ()- and ()-1,2-dichloroethene (CHClCHCl) under atmospheric conditions. Relative and absolute rate methods were used to measure (Cl + ()-CHClCHCl) = (8.80 ± 1.75) × 10, (Cl + ()-CHClCHCl) = (8.51 ± 1.69) × 10, (OH + ()-CHClCHCl) = (2.02 ± 0.43) × 10, (OH + ()-CHClCHCl) = (1.94 ± 0.43) × 10, (O + ()-CHClCHCl) = (4.50 ± 0.45) × 10, and (O + ()-CHClCHCl) = (1.02 ± 0.10) × 10 cm molecule s in 700 Torr of N/air diluent at 298 ± 2 K. Pressure dependencies for the Cl atom reaction kinetics were observed for both isomers, consistent with isomerization occurring Cl atom elimination from the chemically activated CHCl-CHCl-Cl adduct. The observed products from Cl initiated oxidation were HC(O)Cl (117-133%), CHClCHO (29-30%), and the corresponding CHClCHCl isomer (11-20%). OH radical initiated oxidation gives HC(O)Cl as a major product. For reaction of OH with ()-CHClCHCl, ()-CHClCHCl was also observed as a product. A significant chlorine atom elimination channel was observed experimentally (HCl yield) and supported by computational results. Photochemical ozone creation potentials of 12 and 11 were estimated for ()- and ()-CHClCHCl, respectively. Finally, an empirical kinetic relationship is explored for the addition of OH radicals or Cl atoms to small alkenes. The results are discussed in the context of the atmospheric chemistry of ()- and ()-CHClCHCl.