β-Hydroxycarbonyls can be formed from the gas-phase reactions of alkenes with the OH radical, both in the presence and in the absence of NO. To date, because of analytical difficulties, few data have been reported for the formation of this class of compound from the reactions of the OH radical with alkenes. We have determined that β-hydroxyketones can be readily analyzed by gas chromatography, and in this work we have shown that in 1 atm of air the β-hydroxyalkoxy radicals formed in the reactions of the OH radical with trans-2-butene, trans-3-hexene, 1-butene, and α-pinene in the presence of NO primarily decompose rather than react with O{sub}2. Rate constant ratios k{sub}d/k{sub}(O{sub}2) (or lower limits thereof), where k{sub}d and k{sub}(O{sub}2) are respectively the rate constants for the decomposition and the reaction with O{sub}2 of the intermediate β-hydroxyalkoxy radicals, have been obtained for the reactions of the CH{sub}3CH(O)CH(OH)CH{sub}3, CH{sub}3CH{sub}2CH(O)CH{sub}2OH, and CH{sub}3CH{sub}2CH(O)CH(OH)CH{sub}2CH{sub}3 radicals at 296±2 K and atmospheric pressure. Using the 03 reactions with the alkenes to generate OH radicals, the reactions of the OH radical with trans-2-butene, trans-3-hexene, and α-pinene in the absence of NO lead to the formation of the expected β-hydroxycarbonyls and (at least for trans-2-butene) the α,β-diol.
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