Skip to main content

Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations

Journal Article


Download full-text (Open Access)

Abstract


  • The reactions of distonic 4-(N,N,N-trimethylammonium)-2-methylphenyl and 5-(N,N,N-trimethylammonium)-2-methylphenyl radical cations (m/z 149) with O 2 are studied in the gas phase using ion-trap mass spectrometry. Photodissociation (PD) of halogenated precursors gives rise to the target distonic charge-tagged methylphenyl radical whereas collision-induced dissociation (CID) is found to produce unreactive radical ions. The PD generated distonic radicals, however, react rapidly with O2 to form [M + O2]•+ and [M + O2 - OH]•+ ions, detected at m/z 181 and m/z 164, respectively. Quantum chemical calculations using G3SX(MP3) and M06-2X theories are deployed to examine key decomposition pathways of the 5-(N,N,N-trimethylammonium)-2-methylphenylperoxyl radical and rationalise the observed product ions. The prevailing product mechanism involves a 1,5-H shift in the peroxyl radical forming a QOOH-type intermediate that subsequently eliminates •OH to yield charge-tagged 2-quinone methide. Our study suggests that the analogous process should occur for the neutral methylphenyl + O2 reaction, thus serving as a plausible source of •OH radicals in combustion environments.

Authors


  •   Prendergast, Matthew (external author)
  •   Cooper, Phillip A. (external author)
  •   Kirk, Benjamin B. (external author)
  •   da Silva, Gabriel (external author)
  •   Blanksby, Stephen J. (external author)
  •   Trevitt, Adam J.

Publication Date


  • 2013

Citation


  • Prendergast, M., Cooper, P. A., Kirk, B. B., da Silva, G., Blanksby, S. J. & Trevitt, A. J. (2013). Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations. Physical Chemistry Chemical Physics, 15 (47), 20577-20584.

Scopus Eid


  • 2-s2.0-84887856125

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2244&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/1226

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 20577

End Page


  • 20584

Volume


  • 15

Issue


  • 47

Place Of Publication


  • United Kingdom

Abstract


  • The reactions of distonic 4-(N,N,N-trimethylammonium)-2-methylphenyl and 5-(N,N,N-trimethylammonium)-2-methylphenyl radical cations (m/z 149) with O 2 are studied in the gas phase using ion-trap mass spectrometry. Photodissociation (PD) of halogenated precursors gives rise to the target distonic charge-tagged methylphenyl radical whereas collision-induced dissociation (CID) is found to produce unreactive radical ions. The PD generated distonic radicals, however, react rapidly with O2 to form [M + O2]•+ and [M + O2 - OH]•+ ions, detected at m/z 181 and m/z 164, respectively. Quantum chemical calculations using G3SX(MP3) and M06-2X theories are deployed to examine key decomposition pathways of the 5-(N,N,N-trimethylammonium)-2-methylphenylperoxyl radical and rationalise the observed product ions. The prevailing product mechanism involves a 1,5-H shift in the peroxyl radical forming a QOOH-type intermediate that subsequently eliminates •OH to yield charge-tagged 2-quinone methide. Our study suggests that the analogous process should occur for the neutral methylphenyl + O2 reaction, thus serving as a plausible source of •OH radicals in combustion environments.

Authors


  •   Prendergast, Matthew (external author)
  •   Cooper, Phillip A. (external author)
  •   Kirk, Benjamin B. (external author)
  •   da Silva, Gabriel (external author)
  •   Blanksby, Stephen J. (external author)
  •   Trevitt, Adam J.

Publication Date


  • 2013

Citation


  • Prendergast, M., Cooper, P. A., Kirk, B. B., da Silva, G., Blanksby, S. J. & Trevitt, A. J. (2013). Hydroxyl radical formation in the gas phase oxidation of distonic 2-methylphenyl radical cations. Physical Chemistry Chemical Physics, 15 (47), 20577-20584.

Scopus Eid


  • 2-s2.0-84887856125

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2244&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/1226

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 20577

End Page


  • 20584

Volume


  • 15

Issue


  • 47

Place Of Publication


  • United Kingdom