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dc.contributor.authorWalton, John C.
dc.date.accessioned2018-09-14T23:35:40Z
dc.date.available2018-09-14T23:35:40Z
dc.date.issued2017-10-12
dc.identifier.citationWalton , J C 2017 , ' Radical-enhanced acidity : why bicarbonate, carboxyl, hydroperoxyl, and related radicals are so acidic ' , Journal of Physical Chemistry A , vol. 121 , no. 40 , pp. 7761-7767 . https://doi.org/10.1021/acs.jpca.7b08081en
dc.identifier.issn1089-5639
dc.identifier.otherPURE: 251433358
dc.identifier.otherPURE UUID: 5f53d573-d963-439b-96a0-53099a2e14b7
dc.identifier.otherRIS: urn:E05B9547225122F3B03CCF0FFFDE6C91
dc.identifier.otherScopus: 85031330488
dc.identifier.otherORCID: /0000-0003-2746-6276/work/56638792
dc.identifier.otherWOS: 000413131300035
dc.identifier.urihttps://hdl.handle.net/10023/16032
dc.descriptionJ.C.W. thanks EaStCHEM for financial support.en
dc.description.abstractComparison of accepted pKa values of bicarbonate, carboxyl, and hydroperoxyl radicals, with those of models having the unpaired electron replaced by H atoms, implied the acidity of the radicals was greatly increased. A Density Functional Theory computational method of estimating pKas was developed and applied to a set of radicals designed to probe the phenomenon of radical-enhanced deprotonation (RED-shift) and its underlying causes. Comparison of the computed pKa values of 12 acid radicals to those of the corresponding model acids confirmed the intensified acidity of the title radicals and also pin-pointed the carboxy-ethynyl (HO2CC≡C•) and the carboxy-aminyl (HO2CNH•) radicals as having enhanced acidity. The underlying cause was found to be extensive charge distribution away from the anionic O atoms of the conjugate radical anions, coupled with spin density displaced toward these O atoms. Ethyne spacers, between the radical and carboxylate centers, transmitted the effect extremely efficiently such that measurable enhancement was detectable up to at least six alkyne units. The bicyclo[1.1.1]pent-1-yl-3-carboxylic acid radical also displayed enhanced acidity, but additional cage units drastically attenuated the effect. Nitroxide radicals with suitably situated carboxylic acid substituents also exhibited enhanced acidity. Several families of potentially persistent radicals with enhanced acidity were identified.
dc.format.extent7
dc.language.isoeng
dc.relation.ispartofJournal of Physical Chemistry Aen
dc.rightsCopyright © 2017 American Chemical Society. This work has been made available online in accordance with the publisher’s policies. This is the author created accepted version manuscript following peer review and as such may differ slightly from the final published version. The final published version of this work is available at: https://doi.org/10.1021/acs.jpca.7b08081en
dc.subjectQD Chemistryen
dc.subjectNDASen
dc.subjectBDCen
dc.subject.lccQDen
dc.titleRadical-enhanced acidity : why bicarbonate, carboxyl, hydroperoxyl, and related radicals are so acidicen
dc.typeJournal articleen
dc.description.versionPostprinten
dc.contributor.institutionUniversity of St Andrews. School of Chemistryen
dc.contributor.institutionUniversity of St Andrews. EaSTCHEMen
dc.identifier.doihttps://doi.org/10.1021/acs.jpca.7b08081
dc.description.statusPeer revieweden
dc.date.embargoedUntil2018-09-15
dc.identifier.urlhttps://pubs.acs.org/doi/suppl/10.1021/acs.jpca.7b08081en


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