OH Radical Initiated Oxidation of 1,3-Butadiene: Isomeric Selective Study of the Dominant Addition Channel
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- 作者：Buddhadeb Ghosh ; Alejandro Bugarin ; Brian T. Connell ; Simon W. North
- 刊名：Journal of Physical Chemistry A
- 出版年：2010
- 出版时间：April 29, 2010
- 年：2010
- 卷：114
- 期：16
- 页码：5299-5305
- 全文大小：211K
- 年卷期：v.114,no.16(April 29, 2010)
- ISSN：1520-5215
文摘
We report the first isomeric selective kinetic study of the dominant isomeric pathway in the OH initiated oxidation of 1,3-butadiene in the presence of O2 and NO using the laser photolysis−laser induced fluorescence (LP-LIF) technique. The photodissociation of the precursor 2-iodo-but-3-en-1-ol results exclusively in the dominant OH−butadiene addition product, permitting important insight into the OH initiated oxidation mechanism. On the basis of analysis of the time dependent OH/OD signals, we have determined a rate constant for O2 addition to the hydroxyalkyl radical of 7.0−3.0+7.0 × 10−13 cm3 s−1, and we find a value of 1.5−0.6+1.0 × 10−11 cm3 s−1 for the overall reaction rate constant of the hydroxy peroxy radical with NO. We also report the first clear experimental evidence of the (E) form of the δ-hydroxyalkoxy channel through isotopic labeling experiments and provide an upper bound of 13 ± 5% to its branching ratio. This species provides a mechanistic pathway for the formation of 4-hydroxy-2-butenal, which has been identified as a first generation end product. This isomeric selective kinetic study, together with a previous study on the minor channel of the 1,3-butadiene oxidation, yields a comprehensive picture of butadiene oxidation under high NOx conditions relevant to most regions in the continental US.