R. Atkinson, S. M. Aschmann
Feb 1, 1995
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0
Influential Citations
29
Citations
Journal
Environmental science & technology
Abstract
The products of the gas-phase reactions of the OH radical with 2,4-dimethyl-2-pentanol and 3,5-dimethyl-3-hexanol in the presence of NO x have been determined at atmospheric pressure of air and 296 ± 2 Kto assess the occurrence and importance of alkoxy radical isomerization. The products identified and quantified and their formation yields were as follows : from 2,4-dimethyl-2-pentanol : acetone, 0.92 ± 0.15 ; 2-methylpropanal, 0.209 ± 0.022 ; 4-methyl-2-pentanone, 0.046 ± 0.008 ; and 4-hydroxy-4-methyl-2-pentanone, 0.116 ± 0.018 ; from 3,5-dimethyl-3-hexanol: acetone, 0.120 ± 0.029 ; 2-butanone, 0.275 ± 0.021 ; 2-methylpropanal, 0.169 ± 0.016 ; 4-methyl-2-pentanone, 0.161 ± 0.012 ; and 4-hydroxy-4-methyl-2-pentanone, 0.250 ± 0.023. The observed formation of 4-hydroxy-4-methyl-2-pentanone provides conclusive evidence for the occurrence of isomerization of the alkoxy radicals (CH 3 l 2 C(OH)CH 2 C(O)(CH 3 ) 2 and CH 3 CH 2 C(CH 3 )(OH)CH 2 C(O)(CH 3 ) 2 via 1,5-H shifts. The reaction mechanisms are discussed, and isomerization rate constants for 1,5-H-atom abstraction from the -CH 3 and -CH 2 - groups in the RCH 2 C(CH 3 )(OH)-CH 2 C(O)(CH 3 ) 2 alkoxy radicals (R = H and CH 3 ) are derived.