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Product branching fractions of the CH + propene reaction from synchrotron photoionization mass spectrometry

Journal Article


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Abstract


  • The CH(X2Π) + propene reaction is studied in the gas phase at 298 K and 4 Torr (533.3 Pa) using VUV synchrotron photoionization mass spectrometry. The dominant product channel is the formation of C4H6 (m/z 54) + H. By fitting experimental photoionization spectra to measured spectra of known C4H6 isomers, the following relative branching fractions are obtained: 1,3-butadiene (0.63 ± 0.13), 1,2-butadiene (0.25 ± 0.05), and 1-butyne (0.12 ± 0.03) with no detectable contribution from 2-butyne. The CD + propene reaction is also studied and two product channels are observed that correspond to C4H6 (m/z 54) + D and C4H5D (m/z 55) + H, formed at a ratio of 0.4 (m/z 54) to 1.0 (m/z 55). The D elimination channel forms almost exclusively 1,2-butadiene (0.97 ± 0.20) whereas the H elimination channel leads to the formation of deuterated 1,3-butadiene (0.89 ± 0.18) and 1-butyne (0.11 ± 0.02); photoionization spectra of undeuterated species are used in the fitting of the measured m/z 55 (C4H5D) spectrum. The results are generally consistent with a CH cycloaddition mechanism to the C═C bond of propene, forming 1-methylallyl followed by elimination of a H atom via several competing processes. The direct detection of 1,3-butadiene as a reaction product is an important validation of molecular weight growth schemes implicating the CH + propene reaction, for example, those reported recently for the formation of benzene in the interstellar medium (Jones, B. M. Proc. Natl. Acad. Sci. U.S.A. 2011, 108, 452−457).

Authors


  •   Trevitt, Adam J.
  •   Prendergast, Matthew (external author)
  •   Goulay, Fabien (external author)
  •   Savee, John D. (external author)
  •   Osborn, David L. (external author)
  •   Taatjes, Craig A. (external author)
  •   Leone, Stephen R. (external author)

Publication Date


  • 2013

Citation


  • Trevitt, A. J., Prendergast, M. B., Goulay, F., Savee, J. D., Osborn, D. L., Taatjes, C. A. & Leone, S. R. (2013). Product branching fractions of the CH + propene reaction from synchrotron photoionization mass spectrometry. The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory, 117 (30), 6450-6457.

Scopus Eid


  • 2-s2.0-84881144878

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2052&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/1034

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 6450

End Page


  • 6457

Volume


  • 117

Issue


  • 30

Place Of Publication


  • United States

Abstract


  • The CH(X2Π) + propene reaction is studied in the gas phase at 298 K and 4 Torr (533.3 Pa) using VUV synchrotron photoionization mass spectrometry. The dominant product channel is the formation of C4H6 (m/z 54) + H. By fitting experimental photoionization spectra to measured spectra of known C4H6 isomers, the following relative branching fractions are obtained: 1,3-butadiene (0.63 ± 0.13), 1,2-butadiene (0.25 ± 0.05), and 1-butyne (0.12 ± 0.03) with no detectable contribution from 2-butyne. The CD + propene reaction is also studied and two product channels are observed that correspond to C4H6 (m/z 54) + D and C4H5D (m/z 55) + H, formed at a ratio of 0.4 (m/z 54) to 1.0 (m/z 55). The D elimination channel forms almost exclusively 1,2-butadiene (0.97 ± 0.20) whereas the H elimination channel leads to the formation of deuterated 1,3-butadiene (0.89 ± 0.18) and 1-butyne (0.11 ± 0.02); photoionization spectra of undeuterated species are used in the fitting of the measured m/z 55 (C4H5D) spectrum. The results are generally consistent with a CH cycloaddition mechanism to the C═C bond of propene, forming 1-methylallyl followed by elimination of a H atom via several competing processes. The direct detection of 1,3-butadiene as a reaction product is an important validation of molecular weight growth schemes implicating the CH + propene reaction, for example, those reported recently for the formation of benzene in the interstellar medium (Jones, B. M. Proc. Natl. Acad. Sci. U.S.A. 2011, 108, 452−457).

Authors


  •   Trevitt, Adam J.
  •   Prendergast, Matthew (external author)
  •   Goulay, Fabien (external author)
  •   Savee, John D. (external author)
  •   Osborn, David L. (external author)
  •   Taatjes, Craig A. (external author)
  •   Leone, Stephen R. (external author)

Publication Date


  • 2013

Citation


  • Trevitt, A. J., Prendergast, M. B., Goulay, F., Savee, J. D., Osborn, D. L., Taatjes, C. A. & Leone, S. R. (2013). Product branching fractions of the CH + propene reaction from synchrotron photoionization mass spectrometry. The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory, 117 (30), 6450-6457.

Scopus Eid


  • 2-s2.0-84881144878

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2052&context=smhpapers

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/1034

Has Global Citation Frequency


Number Of Pages


  • 7

Start Page


  • 6450

End Page


  • 6457

Volume


  • 117

Issue


  • 30

Place Of Publication


  • United States