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Title:Thermal Decomposition Of Benzyl Radical Via Multiple Active Pathways
Author(s):Buckingham, Grant
Contributor(s):Ellison, Barney; Daily, John W; Nimlos, Mark R; Ormond, Thomas; Robichaud, David
Subject(s):Mini-symposium: Spectroscopy in Kinetics and Dynamics
Abstract:The thermal decomposition of benzyl radical (C$_{6}$H$_{5}$CH$_{2}$) has been investigated using a combination infrared absorption spectroscopy in a neon matrix and 118.2 (10.487 eV) photoionization mass spectrometry. Both techniques are coupled with a heated tubular reactor to allow temperature control over the decomposition to indicate relative barrier heights of fragmentation pathways. Three possible chemical mechanisms have been considered. 1) Ring expansion to cycloheptatrienyl radical (C$_{7}$H$_{7}$) with subsequent breakdown to HCCH and C$_{5}$H$_{5}$, 2) isomerization to the substituted five-membered ring fulvenallene (C$_{5}$H$_{4}$=C=CH$_{2}$), which is of interest to kinetic theorists and finally 3) hydrogen shift to form methyl-substituted phenyl radical, which can then form ortho-benzyne, diacetylene and other fragments. Benzyl radical is generated from two precursors, C$_{6}$H$_{5}$CH$_{2}$CH$_{3}$ and C$_{6}$H$_{5}$CH$_{2}$Br, and both lead to the appearance of HCCH and C$_{5}$H$_{5}$. At slightly hotter temperatures peaks are observed at m/z 90, presumed to be C$_{5}$H$_{4}$=C=CH$_{2}$, and 89, potentially the substituted propargyl C$_{5}$H$_{4}$=C=CH. Additionally, decomposition of isotopically substituted parent molecules C$_{6}$H$_{5}$CD$_{2}$CD$_{3}$ and C$_{6}$D$_{5}$CH$_{2}$CH$_{3}$ indicates C$_{7}$H$_{7}$ as an intermediate due to H/D ratios in fragment molecules.
Issue Date:2014-06-17
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:Buckingham, G.; Ellison, B.; Daily, J.W.; Nimlos, M.R.; Ormond, T.; Robichaud, D. THERMAL DECOMPOSITION OF BENZYL RADICAL VIA MULTIPLE ACTIVE PATHWAYS. Proceedings of the International Symposium on Molecular Spectroscopy, Urbana, IL, June 16-21, 2014. DOI: 10.15278/isms.2014.TC06
Genre:CONFERENCE PAPER/PRESENTATION
Type:Text
Language:English
URI:http://hdl.handle.net/2142/50948
DOI:10.15278/isms.2014.TC06
Rights Information:Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/
Date Available in IDEALS:2014-09-17
2015-04-14


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