In the case of the stabilized alkoxy radical formed in the ethene reaction, decomposition and reaction with

02 are both important at 1 atm in air (Niki et al., 1981; Orlando et al., 1998):

For the /3-hydroxyalkoxy radicals formed from alkenes C5 and larger, there is experimental evidence that isomerization starts to dominate (e.g., see Atkinson et al., 1995d; Kwok et al., 1996b). Thus, isomerization followed by reaction with 02, NO, etc., ultimately leads to the formation of dihydroxycarbonyl compounds. For the reaction of OH with 1-butene, for example, isomerization of one of the alkoxy radicals ultimately leads to 3,4-dihydroxybutanal in competition with its decomposition and reaction with 02:

characteristic manner with 02:

•CH2OH + 02 -> HCHO + H02, k = 9.4 X 10"12 cm3 molecule-1 s"1

The larger a-hydroxy radicals react in a similar manner:

Interestingly, the mechanism appears to involve the initial addition of 02 to the carbon radical, followed by isomerization and decomposition:

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