Kinetic studies of the reactions CH3+NO2→products, CH3O+NO2→products, and OH+CH3C(O)CH3→CH3C(O)OH+CH3, over a range of temperature and pressure

Article abstract of DOI:10.1021/jp0005726

The title reactions were investigated using pulsed laser photolysis combined with pulsed laser induced fluorescence detection of CH₃O to determine the rate coefficients for CH₃+NO₂→products (3) and CH₃O+NO₂→products (5) as a function of temperature and pressure, and to estimate the yield of CH₃ (and thus the yield of CH₃C(O)OH) from the reaction of OH with CH₃C(O)CH₃ (2) at two different temperatures. Reaction 3 has both bimolecular and termolecular components: a simplified falloff parametrization with F_cent = 0.6 gives k_3b⁰ = (3.2±1.3)×10^-28(T/297)^-0.3 cm⁶ s^-1 and k_3b^∞ = (4.3±0.4)×10^-11(T/297)^-1.2 cm³ s^-1 with CH₃NO₂ the likely product. The rate constant for the bimolecular reaction pathway to form CH₃O+NO (3a) was found to be 1.9×10^-11 cm^-3 s^-1. The low- and high-pressure limiting rate coefficients for reaction between CH₃O and NO₂ to form CH₃ONO₂ (5b) were derived as k_5b⁰ = (5.3±0.3)×10^-29(T/297)^-4.4 cm⁶ s^-1 and k_5b^∞ = (1.9±0.05)×10^-11(T/297)^-1.9 cm³ s^-1, respectively. Although the final result is associated with some experimental uncertainty, we find that CH₃ is formed in the reaction between OH and CH₃C(O)CH₃ at ≈50% yield at room temperature and 30% at 233 K.