Role of the α-hydroxyethylperoxy radical in the reactions of acetaldehyde and vinyl alcohol with HO2

The title reactions have been studied theoretically. At atmospheric conditions the acetaldehyde + HO2 reaction forms the α-hydroxyethylperoxy radical with rate constant of around 1011 cm3 mol−1 s−1. Further reaction of α-hydroxyethylperoxy with NO occurs for NO levels above around 10 ppb. Reaction with HO2 is therefore predicted to be a major sink of aldehydes in highly polluted areas, producing carboxylic acids and ozone. The reaction of vinyl alcohol with HO2 can be rapid at combustion temperatures, forming acetaldehyde + HO2 and α-hydroxyethyl + O2 products. This reaction achieves the isomerization of vinyl alcohol to acetaldehyde at a faster rate than keto-enol tautomerization, given suitably high levels of HO2.