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Isomer specific product detection in the reaction of CH with acrolein

Journal Article


Abstract


  • The products formed in the reaction between the methylidene radical (CH) and acrolein (CH2═CHCHO) are probed at 4 Torr and 298 K employing tunable vacuum-ultraviolet synchrotron light and multiplexed photoionization mass-spectrometry. The data suggest a principal exit channel of H loss from the adduct to yield C4H4O, accounting for (78 ± 10)% of the products. Examination of the photoionization spectra measured upon reaction of both CH and CD with acrolein reveals that the isomeric composition of the C4H4O product is (60 ± 12)% 1,3-butadienal and (17 ± 10)% furan. The remaining 23% of the possible C4H4O products cannot be accurately distinguished without more reliable photoionization spectra of the possible product isomers but most likely involves oxygenated butyne species. In addition, C2H2O and C3H4 are detected, which account for (14 ± 10)% and (8 +10, −8)% of the products, respectively. The C2H2O photoionization spectrum matches that of ketene and the C3H4 signal is composed of (24 ± 14)% allene and (76 ± 22)% propyne, with an upper limit of 8% placed on the cyclopropene contribution. The reactive potential energy surface is also investigated computationally, and specific rate coefficients are calculated with RRKM theory. These calculations predict overall branching fractions for 1,3-butadienal and furan of 27% and 12%, respectively, in agreement with the experimental results. In contrast, the calculations predict a prominent CO + 2-methylvinyl product channel that is at most a minor channel according to the experimental results. Studies with the CD radical strongly suggest that the title reaction proceeds predominantly via cycloaddition of the radical onto the C═O bond of acrolein, with cycloaddition to the C═C bond being the second most probable reactive mechanism.

Authors


  •   Lockyear, Jessica F. (external author)
  •   Welz, Oliver (external author)
  •   Savee, John D. (external author)
  •   Goulay, Fabien (external author)
  •   Trevitt, Adam J.
  •   Taatjes, Craig A. (external author)
  •   Osborn, David L. (external author)
  •   Leone, Stephen R. (external author)

Publication Date


  • 2013

Citation


  • Lockyear, J. F., Welz, O., Savee, J. D., Goulay, F., Trevitt, A. J., Taatjes, C. A., Osborn, D. L. & Leone, S. R. (2013). Isomer specific product detection in the reaction of CH with acrolein. The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory, 117 (43), 11013-11026.

Scopus Eid


  • 2-s2.0-84887033273

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/1288

Has Global Citation Frequency


Number Of Pages


  • 13

Start Page


  • 11013

End Page


  • 11026

Volume


  • 117

Issue


  • 43

Place Of Publication


  • United States

Abstract


  • The products formed in the reaction between the methylidene radical (CH) and acrolein (CH2═CHCHO) are probed at 4 Torr and 298 K employing tunable vacuum-ultraviolet synchrotron light and multiplexed photoionization mass-spectrometry. The data suggest a principal exit channel of H loss from the adduct to yield C4H4O, accounting for (78 ± 10)% of the products. Examination of the photoionization spectra measured upon reaction of both CH and CD with acrolein reveals that the isomeric composition of the C4H4O product is (60 ± 12)% 1,3-butadienal and (17 ± 10)% furan. The remaining 23% of the possible C4H4O products cannot be accurately distinguished without more reliable photoionization spectra of the possible product isomers but most likely involves oxygenated butyne species. In addition, C2H2O and C3H4 are detected, which account for (14 ± 10)% and (8 +10, −8)% of the products, respectively. The C2H2O photoionization spectrum matches that of ketene and the C3H4 signal is composed of (24 ± 14)% allene and (76 ± 22)% propyne, with an upper limit of 8% placed on the cyclopropene contribution. The reactive potential energy surface is also investigated computationally, and specific rate coefficients are calculated with RRKM theory. These calculations predict overall branching fractions for 1,3-butadienal and furan of 27% and 12%, respectively, in agreement with the experimental results. In contrast, the calculations predict a prominent CO + 2-methylvinyl product channel that is at most a minor channel according to the experimental results. Studies with the CD radical strongly suggest that the title reaction proceeds predominantly via cycloaddition of the radical onto the C═O bond of acrolein, with cycloaddition to the C═C bond being the second most probable reactive mechanism.

Authors


  •   Lockyear, Jessica F. (external author)
  •   Welz, Oliver (external author)
  •   Savee, John D. (external author)
  •   Goulay, Fabien (external author)
  •   Trevitt, Adam J.
  •   Taatjes, Craig A. (external author)
  •   Osborn, David L. (external author)
  •   Leone, Stephen R. (external author)

Publication Date


  • 2013

Citation


  • Lockyear, J. F., Welz, O., Savee, J. D., Goulay, F., Trevitt, A. J., Taatjes, C. A., Osborn, D. L. & Leone, S. R. (2013). Isomer specific product detection in the reaction of CH with acrolein. The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory, 117 (43), 11013-11026.

Scopus Eid


  • 2-s2.0-84887033273

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/1288

Has Global Citation Frequency


Number Of Pages


  • 13

Start Page


  • 11013

End Page


  • 11026

Volume


  • 117

Issue


  • 43

Place Of Publication


  • United States