Atmospheric oxidation mechanism of methyl acetate

Smog chamber/FTIR techniques were used to study the Cl atom initiated oxidation of CH3C(O)OCH3 in 700 Torr of N-2/O-2 at 296 K. Relative rate techniques were used to measure k(Cl+CH3C(O)OCH3) = (2.2 +/- 0.3) x 10(-12), k(Cl+CH3C(O)CH3) = (2.2 +/- 0.4) x 10(-12), k(Cl+CH3C(O)OC(O)H) = (1.0 +/- 0.1) x 10(-13), and k(Cl+ ClCH2C(O)OCH3) = (8.5 +/- 1.9) x 10(-13) cm(3) molecule(-1) s(-1). The reaction of Cl+CH3C(O)OCH3 was found to proceed more than 95% via H-abstraction at the -OCH3 site. The fate of the CH3C(O)OCH2O . radical was studied in 700 Torr of N-2/O-2 diluent at 296 K in the absence and presence of NO. Two loss mechanisms were identified: reaction with O-2 to give CH3C(O)OC(O)H and alpha-ester rearrangement to give CH3C(O)OH and HCO . radicals. It was found that alpha-ester rearrangement is more likely when CH3C(O)-OCH2O . radicals were produced via the CH3C(O)OCH2O2. + NO reaction than when they were produced via the self-reaction of peroxy radicals. In one atmosphere of air ([O-2] 160 Torr) containing NO at 296 K it can be calculated that 65 +/- 14% of the CH3C(O)OCH2O . radicals undergo alpha-ester rearrangement while 35 +/- 5% react with O-2.