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Unimolecular reaction chemistry of a charge-tagged beta-hydroxyperoxyl radical

Journal Article


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Abstract


  • β-Hydroxyperoxyl radicals are formed during atmospheric oxidation of unsaturated volatile organic compounds such as isoprene. They are intermediates in the combustion of alcohols. In these environments the unimolecular isomerization and decomposition of β-hydroxyperoxyl radicals may be of importance, either through chemical or thermal activation. We have used ion-trap mass spectrometry to generate the distonic charge-tagged β-hydroxyalkyl radical anion, ˙CH2C(OH)(CH3)CH2C(O)O−, and investigated its subsequent reaction with O2 in the gas phase under conditions that are devoid of complicating radical–radical reactions. Quantum chemical calculations and master equation/RRKM theory modeling are used to rationalize the results and discern a reaction mechanism. Reaction is found to proceed via initial hydrogen abstraction from the γ-methylene group and from the β-hydroxyl group, with both reaction channels eventually forming isobaric product ions due to loss of either ˙OH + HCHO or ˙OH + CO2. Isotope labeling studies confirm that a 1,5-hydrogen shift from the β-hydroxyl functionality results in a hydroperoxyalkoxyl radical intermediate that can undergo further unimolecular dissociations. Furthermore, this study confirms that the facile decomposition of β-hydroxyperoxyl radicals can yield ˙OH in the gas phase.

Authors


  •   So, Sui (external author)
  •   Kirk, Benjamin B. (external author)
  •   Trevitt, Adam J.
  •   Wille, Uta (external author)
  •   Blanksby, Stephen J. (external author)
  •   da Silva, Gabriel (external author)

Publication Date


  • 2014

Citation


  • So, S., Kirk, B. B., Trevitt, A. J., Wille, U., Blanksby, S. J. & da Silva, G. (2014). Unimolecular reaction chemistry of a charge-tagged beta-hydroxyperoxyl radical. Physical Chemistry Chemical Physics, 16 (45), 24954-24964.

Scopus Eid


  • 2-s2.0-84908429075

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=3381&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/2363

Has Global Citation Frequency


Number Of Pages


  • 10

Start Page


  • 24954

End Page


  • 24964

Volume


  • 16

Issue


  • 45

Place Of Publication


  • United Kingdom

Abstract


  • β-Hydroxyperoxyl radicals are formed during atmospheric oxidation of unsaturated volatile organic compounds such as isoprene. They are intermediates in the combustion of alcohols. In these environments the unimolecular isomerization and decomposition of β-hydroxyperoxyl radicals may be of importance, either through chemical or thermal activation. We have used ion-trap mass spectrometry to generate the distonic charge-tagged β-hydroxyalkyl radical anion, ˙CH2C(OH)(CH3)CH2C(O)O−, and investigated its subsequent reaction with O2 in the gas phase under conditions that are devoid of complicating radical–radical reactions. Quantum chemical calculations and master equation/RRKM theory modeling are used to rationalize the results and discern a reaction mechanism. Reaction is found to proceed via initial hydrogen abstraction from the γ-methylene group and from the β-hydroxyl group, with both reaction channels eventually forming isobaric product ions due to loss of either ˙OH + HCHO or ˙OH + CO2. Isotope labeling studies confirm that a 1,5-hydrogen shift from the β-hydroxyl functionality results in a hydroperoxyalkoxyl radical intermediate that can undergo further unimolecular dissociations. Furthermore, this study confirms that the facile decomposition of β-hydroxyperoxyl radicals can yield ˙OH in the gas phase.

Authors


  •   So, Sui (external author)
  •   Kirk, Benjamin B. (external author)
  •   Trevitt, Adam J.
  •   Wille, Uta (external author)
  •   Blanksby, Stephen J. (external author)
  •   da Silva, Gabriel (external author)

Publication Date


  • 2014

Citation


  • So, S., Kirk, B. B., Trevitt, A. J., Wille, U., Blanksby, S. J. & da Silva, G. (2014). Unimolecular reaction chemistry of a charge-tagged beta-hydroxyperoxyl radical. Physical Chemistry Chemical Physics, 16 (45), 24954-24964.

Scopus Eid


  • 2-s2.0-84908429075

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=3381&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/2363

Has Global Citation Frequency


Number Of Pages


  • 10

Start Page


  • 24954

End Page


  • 24964

Volume


  • 16

Issue


  • 45

Place Of Publication


  • United Kingdom