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Issue 2, 2012
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Crossed beam reaction of phenyl and D5-phenyl radicals with propene and deuterated counterparts—competing atomic hydrogen and methyl loss pathways

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Abstract

We conducted the crossed molecular beams reactions of the phenyl and D5-phenyl radicals with propylene together with its partially deuterated reactants at collision energies of ∼45 kJ mol−1 under single collision conditions. The scattering dynamics were found to be indirect and were mainly dictated by an addition of the phenyl radical to the sterically accessible CH2 unit of the propylene reactant. The resulting doublet radical isomerized to multiple C9H11 intermediates, which were found to be long-lived, decomposing in competing methyl group loss and atomic hydrogen loss pathways with the methyl group loss leading to styrene (C6H5C2H3) and the atomic hydrogen loss forming C9H10 isomers cis/trans1-phenylpropene (CH3CHCHC6H5) and 3-phenylpropene (C6H5CH2C2H3). Fractions of the methylversushydrogen loss channels of 68 ± 16% : 32 ± 10% were derived experimentally, which agrees nicely with RRKM theory. As the collision energy rises to 200 kJmol−1, the contribution of the methyl loss channel decreases sharply to typically 25%; the decreased importance of the methyl group loss channel was also demonstrated in previous crossed beam experiments conducted at elevated collision energies of 130–193 kJ mol−1. The presented work highlights the interesting differences of the branching ratios with rising collision energies in the reaction dynamics of phenyl radicals with unsaturated hydrocarbons related to combustion processes. The facility of forming styrene, a common molecule found in combustion against the elusiveness of forming the cyclic indane molecule demonstrates the need to continue to explore the potential surfaces through the combinative single collision experiment and electronic structure calculations.

Graphical abstract: Crossed beam reaction of phenyl and D5-phenyl radicals with propene and deuterated counterparts—competing atomic hydrogen and methyl loss pathways

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Publication details

The article was received on 29 Aug 2011, accepted on 31 Oct 2011 and first published on 25 Nov 2011


Article type: Paper
DOI: 10.1039/C1CP22758K
Citation: Phys. Chem. Chem. Phys., 2012,14, 720-729
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    Crossed beam reaction of phenyl and D5-phenyl radicals with propene and deuterated counterparts—competing atomic hydrogen and methyl loss pathways

    R. I. Kaiser, D. S. N. Parker, M. Goswami, F. Zhang, V. V. Kislov, A. M. Mebel, J. Aguilera-Iparraguirre and W. H. Green, Phys. Chem. Chem. Phys., 2012, 14, 720
    DOI: 10.1039/C1CP22758K

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