FTIR Spectroscopic Study of the Cl-Atom-Initiated Reactions of Ethylene Oxide in O2/N2 Diluent

Article abstract of DOI:10.1021/j100012a030

A long-path FTIR spectroscopic study of the Cl-atom-initiated reactions of ethylene oxide was carried out at 297+/-2 K in the photolysis (300 mn) of mixtures containing and Cl2 in both the torr millitorr ranges in 700 Torr of N2 or O2/N2 diluent.In 700 Torr of N2, the only primary product detected was , formed via (1) Cl+ -> + HCl followed by (2) + Cl2 -> + Cl.Thus, the cyclic oxiranyl radical formed in reaction 1 was sufficiently long-lived to react with Cl2.An upper limit value of k₃4 s^-1 has been esmimated for the rate constant of the possible oxiranyl-to-vinoxy isomerization: (3) -> CH2CHO.The yield decreased with increase in added O2 due to the occurrence of reaction 4: (4) + O2 (+M) -> (+M).A value of k₂/k₄=2.0+/-0.4 was derived from the O2 dependence of the yield.In 700 Torr of air, the observed products included C-O-C bonded compounds HC(O)OCHO and CH2(OH)OCHO, and one-carbon species CO, CO2, HCHO, and HC(O)OH, but not C-C bonded products.The preferential formation of C-O-C rather than C-C bonded products suggests the predominant cleavage of the C-C bond rather than the C-O bond in a three membered ring precursor radical.The most likely candidate is the cyclic radical formed via self-reaction, i.e. -> + O2.A detailed mechanism is proposed for the oxidation of the radical leading to the formation of the observed products.