Atmospheric oxidation of vinyl and allyl acetate: Product distribution and mechanisms of the OH-initiated degradation in the presence and absence of NOx

Abstract

The products formed from the reactions of OH radicals with vinyl acetate and allyl acetate have been studied in a 1080 L quartz-glass chamber in the presence and absence of NOx using in situ FTIR spectroscopy to monitor the reactant decay and product formation. The yields of the primary products formed in the reaction of OH with vinyl acetate were: formic acetic anhydride (84 ± 11)%; acetic acid (18 ± 3)% and formaldehyde (99 ± 15)% in the presence of NOx and formic acetic anhydride (28 ± 5)%; acetic acid (87 ± 12)% and formaldehyde (52 ± 8)% in the absence of NOx. For the reaction of OH with allyl acetate the yields of the identified products were: acetoxyacetaldehyde (96 ± 15)% and formaldehyde (90 ± 12)% in the presence of NOx and acetoxyacetaldehyde (26 ± 4)% and formaldehyde (12 ± 3)% in the absence of NOx. The present results indicate that in the absence of NOx the main fate of the 1,2-hydroxyalkoxy radicals formed after addition of OH to the double bond in the compounds is, in the case of vinyl acetate, an α-ester rearrangement to produce acetic acid and CH 2(OH)CO• radicals and in the case of allyl acetate reaction of the radical with O2 to form acetic acid 3-hydroxy-2-oxo-propyl ester (CH3C(O)OCH2C(O)CH 2OH). In contrast, in the presence of NOx the main reaction pathway for the 1,2-hydroxyalkoxy radicals is decomposition. The results are compared with the available literature data and implications for the atmospheric chemistry of vinyl and allyl acetate are assessed. © 2012 American Chemical Society.