An EPR and DFT study on the primary radical formed in hydroxylation reactions of 2,6-dimethoxy-1,4-benzoquinone

Haeri, Haleh H. and Bogeski, Ivan and Gulaboski, Rubin and Mirceski, Valentin and Hoth, Markus and Kappl, Reinhard (2016) An EPR and DFT study on the primary radical formed in hydroxylation reactions of 2,6-dimethoxy-1,4-benzoquinone. Molecular Physics. pp. 1-11. ISSN 0026-8976

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The quinone compound 2,6-dimethoxy-1,4-benzoquinone is hydroxylated in alkaline aqueous solutionwithpHabove12.Electronparamagneticresonanceexperimentsshowedthattwotransientradicals are formed in this reaction. The radical appearing first is assigned to a one electron reduced 2,6-dimethoxy-1,4-benzoquinone,receivingtheelectronfromanintermediateanionichydroxylated species.Forthisprimaryradical,allprotoncouplingsweredetermined(quinoidringprotons:1.453G, methylprotons:0.795G).Thedensityfunctionaltheorymethodwasappliedtoobtainelectronicand structuralinformationoftheprimaryradicalandasolutionstructureissuggested.Forapproaching the experimental hyperfine couplings in theoretical models, it was necessary to consider effects of external polarisation arising from water molecules near one carbonyl group, and the orientation of methoxygroupstowardsthequinonering.Withthisapproach,thesecondaryradicalformedinthe hydroxylation reaction, and the transient radicals found for other biologically important quinones (includingcoenzymesQ)andtheirhydroxylatedspeciesmaybecomeaccessible.

Item Type: Article
Subjects: Medical and Health Sciences > Basic medicine
Natural sciences > Chemical sciences
Natural sciences > Physical sciences
Divisions: Faculty of Medical Science
Depositing User: Rubin Gulaboski
Date Deposited: 24 Mar 2016 10:28
Last Modified: 24 Mar 2016 10:28

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