The mechanism of O( 3 P) atom reaction with ethylene and other simple olefins

Reactions of oxygen atoms with ethylene, propene, and 2‐butene were studied at room temperature under discharge flow conditions by resonance fluorescence spectroscopy of O and H atoms at pressures of 0.08 to 12 torr. The measured total rate constants of these reactions are K   C   2  H   4= (7.8 ± 0.6)·10 −13 cm 3 s −1 , K   C   3  H   6= (4.3 ± 0.4) ± 10 −12 cm 3 s −1 , K   C   4  H   8= (1.4 ± 0.4) · 10 −11 cm 3 s −1 . The branching ratios of H atom elimination channels were measured for reactions of O atoms with ethylene and propene. No H‐atom elimination was found for the reaction of O‐atoms with 2‐butene. A redistribution of reaction O + C 2   H   4channels with pressure was found. A mechanism of the O + C 2   H   4reaction was proposed and the possibility of its application to other olefins is discussed. On the basis of mechanism the pressure dependence of the total rate constant for reaction O + C 2   H   4was predicted and experimentally confirmed in the pressure range 0.08–1.46 torr.