Atmospheric oxidation mechanism of methyl propionate

Smog chamber FTIR techniques were used to study the atmospheric oxidation of methyl propionate in 740 Torr of air in the presence of NOx at 296 +/- 2K. Relative rate techniques were used to measure k(OH + CH3CH2C(O)OCH3) = (9.29 +/- 1.13) x 10(-13), k(Cl + CH3CH2C(O)OCH3) = (1.51 +/- 0.22) x 10(-11), k(Cl + CH3CH2C(O)OC(O)H) = (2.89 +/- 0.35) x 10(-12), k(Cl + CH3CH2C(O)OH) = (4.72 +/- 0.62) x 10(-12), and k(Cl + CH3C(O)C(O)OCH3) = (4.99 +/- 0.96) x 10(-13) cm(3) molecule(-1) s(-1). The products (and molar yields) formed in the Cl-atom initiated oxidation of methyl propionate were as follows: propionic formic anhydride (CH3CH2C(O)OC(O)H), 0.099 +/- 0.019; propionic acid (CH3CH2C(O)OH), 0.139 +/- 0.027; carbon monoxide, 0.132 +/- 0.026; methyl pyruvate (CH3C(O)C(O)OCH3), 0.289 +/- 0.057; acetaldehyde, 0.077 +/- 0.015; methoxy formylperoxynitrate (CH3OC(O)O2NO2), 0.083 +/- 0.016; methyl glyoxylate (H(O)CC(O)OCH3), 0.111 +/- 0.022; organic nitrates, 0.07 +/- 0.02; and formaldehyde. These products account for 79 +/- 16% of the loss of methyl propionate. The atmospheric oxidation mechanism of methyl propionate is presented and discussed.