Radicals from the gas-phase pyrolysis of catechol. 2. Comparison of the pyrolysis of catechol and hydroquinone.
Summary of "Radicals from the gas-phase pyrolysis of catechol. 2. Comparison of the pyrolysis of catechol and hydroquinone."
Formation of radicals from the pyrolysis of catechol (CT) and hydroquinone (HQ) over a temperature range of 350-900 °C was studied using low-temperature matrix isolation electron paramagnetic resonance (LTMI EPR) spectroscopy. Comparative analysis of the pyrolysis mechanisms of these isomeric compounds was performed, and the role of semiquinone-type carrier radicals was studied. Pathways of unimolecular decomposition of intermediate radicals and molecular products were identified from the examination of the potential energy surface of catechol calculated at B3LYP hybrid density functional theory and composite CBS-QB3 levels. The results were compared with the experimental observations and mechanistic pathways previously developed for the pyrolysis of hydroquinone.
Affiliation
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA. Lkhach1@lsu.edu
Journal Details
This article was published in the following journal.
Name: The journal of physical chemistry. A
ISSN: 1520-5215
Pages: 10110-6
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20731470
- DOI: http://dx.doi.org/10.1021/jp1054588
Medical and Biotech [MESH] Definitions
Catechol O-methyltransferase
Enzyme that catalyzes the movement of a methyl group from S-adenosylmethionone to a catechol or a catecholamine. EC 2.1.1.6.
Catechol 1,2-dioxygenase
An enzyme that catalyzes the oxidation of catechol to muconic acid with the use of Fe3+ as a cofactor. This enzyme was formerly characterized as EC 1.13.1.1 and EC 1.99.2.2.
Catechol Oxidase
An enzyme of the oxidoreductase class that catalyzes the reaction between catechol and oxygen to yield benzoquinone and water. It is a complex of copper-containing proteins that acts also on a variety of substituted catechols. EC 1.10.3.1.
Catechol 2,3-dioxygenase
Catalyzes the oxidation of catechol to 2-hydroxymuconate semialdehyde in the carbazole and BENZOATE degradation via HYDROXYLATION pathways. It also catalyzes the conversion of 3-methylcatechol to cis, cis-2-hydroxy-6-oxohept-2,4-dienoate in the TOLUENE and XYLENE degradation pathway. This enzyme was formerly characterized as EC 1.13.1.2.
Flame Ionization
Pyrolysis of organic compounds at the temperature of a hydrogen-air flame to produce ionic intermediates which can be collected and the resulting ion current measured by gas chromatography.
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