Mechanism for the Reaction of CH2OO with SO2

Article abstract of DOI:10.1021/j100408a059

The gas-phase reaction of CH2OO produced by the reaction of ozone with ethylene was investigated.The pressure dependence of the yield of H2SO4 formed in the reaction of CH2OO with SO2 was studied in the pressure range of 10-1140 Torr.The H2SO4 yield (0.40 at the high-pressure limit) decreased as the total pressure decreased but did not fall to zero even at low pressure, which impies that stabilized ground-state CH2OO species are formed at low pressure as a primary product.Vibrationally excited CH2OO<*> as well as another excited CH2OO*, which does not suffer collisional stabilization even at the highest pressure studied, is also produced in the reaction.The formation ratio was obtained as CH2OO:CH2OO<*>:CH2OO*=0.20:0.20:0.60.The ratio of the rate constant for collisional deactivation of CH2OO<*> with air to that for decomposition for CH2OO<*> was determined to be (1.0+/-0.9)*10^-19 cm³/molecule.As for the reaction mechanism for the reaction of CH2OO with SO2, the formation of the adduct between CH2OO and SO2 was concluded.The adduct is proposed to react with another SO2 molecule to produce HCHO and SO3 or to decompose to HCOOH and SO2 with the rate constant ratio of (4.9+/-2.0)*10^-15 cm³/molecule.