CO2 Laser-induced Decomposition of 1,1,2-Trichloroethane

Article abstract of DOI:10.1246/bcsj.58.3528

CH₂ClCHCl₂ was photolyzed with a focusing geometry using the P(24) line of the 10.6 μm CO₂ band (940.6 cm^-1).The final products of neat photolysis were cis- and trans-CHCl=CHCl, CH₂=CCl₂, CH₂=CHCl, CH<*>CCl, CH<*>CH, and C₄H₂.The relative yield of CH₂=CCl₂ in particular was strongly dependent on CH₂ClCHCl₂ pressure and sensitive to the addition of H atom containing molecules.A series of diagnostic experiments shows that the dichloroethene isomers are formed by three different processes, i.e., infrared multiphoton decomposition, collision-induced decomposition, and radical chain reaction.Infrared multiphoton decomposition and collision-induced decomposition give rise to cis- and trans-CHCl=CHCl predominantly, while the radical chain reaction generates the dichloroethane isomers in comparable amounts at high reactant pressures, the most probable initiation step being the C-Cl bond-scission reaction of the parent molecule.Formation mechanisms for other minor products are also discussed.