Please use this identifier to cite or link to this item: https://www.um.edu.mt/library/oar/handle/123456789/69727
Full metadata record
DC FieldValueLanguage
dc.contributor.authorMagri, David C.-
dc.contributor.authorWorkentin, Mark S.-
dc.date.accessioned2021-02-22T07:27:17Z-
dc.date.available2021-02-22T07:27:17Z-
dc.date.issued2008-
dc.identifier.citationMagri, D. C., & Workentin, M. S. (2008). A radical‐anion chain mechanism initiated by dissociative electron transfer to a bicyclic endoperoxide : insight into the fragmentation chemistry of neutral biradicals and distonic radical anions. Chemistry–A European Journal, 14(6), 1698-1709.en_GB
dc.identifier.urihttps://www.um.edu.mt/library/oar/handle/123456789/69727-
dc.description.abstractThe electron-transfer (ET) reduction of two diphenyl-substituted bicyclic endoperoxides was studied in N,N-dimethylformamide by heterogeneous electrochemical techniques. The study provides insight into the structural parameters that affect the reduction mechanism of the O-O bond and dictate the reactivity of distonic radical anions, in addition to evaluating previously unknown thermochemical parameters. Notably, the standard reduction potentials and the bond dissociation energies (BDEs) were evaluated to be -0.550.15 V and 203 kcalmol-1, respectively, the last representing some of the lowest BDEs ever reported. The endoperoxides react by concerted dissociative electron transfer (DET) reduction of the O-O bond yielding a distonic radical-anion intermediate. The reduction of 1,4-diphenyl-2,3-dioxabicyclo[2.2.2]oct-5-ene (1) results in the quantitative formation of 1,4-diphenylcyclohex-2-ene-cis-1,4-diol by an overall two-electron mechanism. In contrast, ET to 1,4-diphenyl-2,3- dioxabicyclo[2.2.2]octane (2) yields 1,4- diphenylcyclohexane-cis-1,4-diol as the major product; however, in competition with the second ET from the electrode, the distonic radical anion undergoes a b-scission fragmentation yielding 1,4-diphenyl-1,4-butanedione radical anion and ethylene in a mechanism involving less than one electron. These observations are rationalized by an unprecedented catalytic radical-anion chain mechanism, the first ever reported for a bicyclic endoperoxide. The product ratios and the efficiency of the catalytic mechanism are dependent on the electrode potential and the concentration of weak non-nucleophilic acid. A thermochemical cycle for calculating the driving force for b-scission fragmentation is presented, and provides insight into why the fragmentation chemistry of distonic radical anions is different from analogous neutral biradicals.en_GB
dc.language.isoenen_GB
dc.publisherWiley-VCH Verlag GmbH & Co. KGaA, Weinheimen_GB
dc.rightsinfo:eu-repo/semantics/restrictedAccessen_GB
dc.subjectEnergy transferen_GB
dc.subjectFragmentation reactionsen_GB
dc.subjectPeroxidesen_GB
dc.subjectIntermediates (Chemistry)en_GB
dc.titleA radical‐anion chain mechanism initiated by dissociative electron transfer to a bicyclic endoperoxide : insight into the fragmentation chemistry of neutral biradicals and distonic radical anionsen_GB
dc.typearticleen_GB
dc.rights.holderThe copyright of this work belongs to the author(s)/publisher. The rights of this work are as defined by the appropriate Copyright Legislation or as modified by any successive legislation. Users may access this work and can make use of the information contained in accordance with the Copyright Legislation provided that the author must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the prior permission of the copyright holder.en_GB
dc.description.reviewedpeer-revieweden_GB
dc.identifier.doi10.1002/chem.200701740-
dc.publication.titleChemistry–A European Journalen_GB
Appears in Collections:Scholarly Works - FacSciChe

Files in This Item:
File Description SizeFormat 
2008 Chem Eur J.pdf
  Restricted Access
552.89 kBAdobe PDFView/Open Request a copy


Items in OAR@UM are protected by copyright, with all rights reserved, unless otherwise indicated.