Journal article
Thermochemical properties and decomposition pathways of three isomeric semiquinone radicals
The Journal of Physical Chemistry A, Vol.114(2), pp.1098-1108
2010
Abstract
Semiquinones are persistent free environmental radicals formed as important initial products from the decomposition of dihydroxylated benzene isomers. This study develops detailed decomposition pathways for the thermal decomposition of the three isomeric semiquinone radicals. Branching ratios based on the calculated high-pressure limit reaction rate constants predict that p-benzoquinone is a major product from the unimolecular decomposition of the p-semiquinone radical, while the formation of o-benzoquinone from the o-semiquinone radical corresponds to a minor channel. This finding is consistent with the absence of o-benzoquinone from the thermal degradation of the 1,2-dihydroxybenzene isomer and the abundance of p-benzoquinone from the thermal decomposition of 1,4-dihydroxybenzene. Ring contraction/CO elimination is shown to be the dominant sink pathway for the o-semiquinone and m-semiquinone radicals. Thermochemical properties, in terms of enthalpies of formation, entropies, and heat capacities for dihydroxylated benzene isomers, semiquinone radicals, and benzoquinones, are evaluated by quantum chemical calculations. Values of the enthalpies of formation calculated by the B3LYP/GTLarge method show good agreement with those obtained at the G3B3 level of theory.
Details
- Title
- Thermochemical properties and decomposition pathways of three isomeric semiquinone radicals
- Authors/Creators
- M. Altarawneh (Author/Creator) - Al-Hussein Bin Talal UniversityB.Z. Dlugogorski (Author/Creator) - Al-Hussein Bin Talal UniversityE.M. Kennedy (Author/Creator) - Al-Hussein Bin Talal UniversityJ.C. Mackie (Author/Creator) - Al-Hussein Bin Talal University
- Publication Details
- The Journal of Physical Chemistry A, Vol.114(2), pp.1098-1108
- Publisher
- American Chemical Society
- Identifiers
- 991005540979707891
- Copyright
- © 2010 American Chemical Society.
- Murdoch Affiliation
- Murdoch University
- Language
- English
- Resource Type
- Journal article
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- Collaboration types
- Domestic collaboration
- International collaboration
- Citation topics
- 2 Chemistry
- 2.15 Physical Chemistry
- 2.15.3 Quantum Chemistry
- Web Of Science research areas
- Chemistry, Physical
- Physics, Atomic, Molecular & Chemical
- ESI research areas
- Chemistry