FTIR Spectroscopic Study of the Mechanism for the Gas-Phase Reaction between Ozone and Tetramethylene

Article abstract of DOI:10.1021/j100288a035

Long-path FTIR spectroscoic product studies were made of mixtures containing part-per-million concentrations of O3 and (CH3)2C=C(CH3)2 (TME) in 700 Torr of O2-N2 to determine the formation and reactions of the dimethyl-substituted Criegee intermediate (CH3)2COO expected from O3 + TME -> (CH3)2COO + (CH3)2C=O.The observed stoichiometry, Δ-/Δ, was typically 1.7, and among the products were CO, CO2, HCHO, CH3OH, CH3OOH, CH3C(=O)OH, CH3C(=O)OOH, (CH3)2C=O, CH3C(=O)CHO, CH3C(=O)CH3, Ch3C(=O)CH2(OH), and products tentatively identified as (CH3)2C(OH)-C(CH3)2OOH and CH3C(=O)CH2(OOH).In addition, 16O- and 18O-labeled products were identified in 18O3-TME-air mixtures, and the effect of added HCHO, CH3CHO, and NO2 (or 15NO2) on the product distribution were determined.The results indicate that ca.25percent of the (CH3)2COO moiety formed was thermally stable, and that the remainder largely dissociated to yield the following free radicals, i.e., (CH3)2 -> CH3C(OOH)=CH2 -> CH3C(=O)CH2^. + HO^..The HO-initiated oxidation of TME was shown to account for the excess cosumption of TME over O3 as well as for some of the major products observed.