| Autor: |
Shiels OJ; Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, 2522, Australia. adamt@uow.edu.au., Prendergast MB; Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, 2522, Australia. adamt@uow.edu.au., Savee JD; Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969, USA., Osborn DL; Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969, USA., Taatjes CA; Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969, USA., Blanksby SJ; Central Analytical Research Facility, Queensland University of Technology, Brisbane, 4001, Australia., da Silva G; Department of Chemical Engineering, The University of Melbourne, Melbourne, Victoria, 3010, Australia., Trevitt AJ; Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, 2522, Australia. adamt@uow.edu.au. |
| Abstrakt: |
Gas-phase reactions of the o-methylphenyl (o-CH3C6H4) radical with the C3H4 isomers allene (H2C[double bond, length as m-dash]C[double bond, length as m-dash]CH2) and propyne (HC[triple bond, length as m-dash]C-CH3) are studied at 600 K and 4 Torr (533 Pa) using VUV synchrotron photoionisation mass spectrometry, quantum chemical calculations and RRKM modelling. Two major dissociation product ions arise following C3H4 addition: m/z 116 (CH3 loss) and 130 (H loss). These products correspond to small polycyclic aromatic hydrocarbons (PAHs). The m/z 116 signal for both reactions is conclusively assigned to indene (C9H8) and is the dominant product for the propyne reaction. Signal at m/z 130 for the propyne case is attributed to isomers of bicyclic methylindene (C10H10) + H, which contains a newly-formed methylated five-membered ring. The m/z 130 signal for allene, however, is dominated by the 1,2-dihydronaphthalene isomer arising from a newly created six-membered ring. Our results show that new ring formation from C3H4 addition to the methylphenyl radical requires an ortho-CH3 group - similar to o-methylphenyl radical oxidation. These reactions characteristically lead to bicyclic aromatic products, but the structure of the C3H4 co-reactant dictates the structure of the PAH product, with allene preferentially leading to the formation of two six-membered ring bicyclics and propyne resulting in the formation of six and five-membered bicyclic structures. |
