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https://hdl.handle.net/1959.11/546
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DC Field | Value | Language |
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dc.contributor.author | Novak, M | en |
dc.contributor.author | Glover, S | en |
dc.date.accessioned | 2008-07-18T12:08:00Z | - |
dc.date.issued | 2005 | - |
dc.identifier.citation | Journal of the American Chemical Society, 127(22), p. 8090-8097 | en |
dc.identifier.issn | 1520-5126 | en |
dc.identifier.issn | 0002-7863 | en |
dc.identifier.issn | 1943-2984 | en |
dc.identifier.uri | https://hdl.handle.net/1959.11/546 | - |
dc.description.abstract | The title compounds serve as potential precursors to aryloxenium ions, often proposed, but primarily uncharacterized intermediates in phenol oxidations. The uncatalyzed and acid-catalyzed decomposition of 4-acetoxy-4-phenyl-2,5-cyclohexadienone, 2a, generates the quinol, 3a. 18O-Labeling studies performed in 18O-H2O, and monitored by LC/MS and 13C NMR spectroscopy that can detect 18O-induced chemical shifts on 13C resonances, show that 3a was generated in both the uncatalyzed and acid-catalyzed reactions by Calkyl-O bond cleavage consistent with formation of an aryloxenium ion. Trapping with N3- and Br- confirms that both uncatalyzed and acid-catalyzed decompositions occur by rate-limiting ionization to form the 4-biphenylyloxenium ion, 1a. This ion has a shorter lifetime in H2O than the corresponding nitrenium ion, 7a (12 ns for 1a, 300 ns for 7a at 30 C). Similar analyses of the product, 3b, of acid- and base-catalyzed decomposition of 4-acetoxy-4-methyl-2,5-cyclohexadienone, 2b, in 18O-H2O show that these reactions are ester hydrolyses that proceed by Cacyl-O bond cleavage processes not involving the p-tolyloxenium ion, 1b. Uncatalyzed decomposition of the more reactive 4-dichloroacetoxy-4-methyl-2,5-cyclohexadienone, 2b', is also an ester hydrolysis, but 2b' undergoes a kinetically second-order reaction with N3- that generates an oxenium ion-like substitution product by an apparent SN2' mechanism. Estimates based on the lifetimes of 1a, 7a, and the p-tolylnitrenium ion, 7b, and the calculated relative stabilities of these ions toward hydration indicate that the aqueous solution lifetime of 1b is ca. 3-5 ps. Simple 4-alkyl substituted aryloxenium ions are apparently not stable enough in aqueous solution to be competitively trapped by nonsolvent nucleophiles. | en |
dc.language | en | en |
dc.publisher | American Chemical Society | en |
dc.relation.ispartof | Journal of the American Chemical Society | en |
dc.title | The Hydrolysis of 4-acyloxy-4-substituted-2,5-cyclohexadienones: Limitations of Aryloxenium Ion Chemistry | en |
dc.type | Journal Article | en |
dc.identifier.doi | 10.1021/ja050899q | en |
dc.subject.keywords | Physical Organic Chemistry | en |
local.contributor.firstname | M | en |
local.contributor.firstname | S | en |
local.subject.for2008 | 030505 Physical Organic Chemistry | en |
local.subject.seo | 780103 Chemical sciences | en |
local.profile.school | School of Science and Technology | en |
local.profile.email | sglover@une.edu.au | en |
local.output.category | C1 | en |
local.record.place | au | en |
local.record.institution | University of New England | en |
local.identifier.epublicationsrecord | pes:2318 | en |
local.publisher.place | United States of America | en |
local.format.startpage | 8090 | en |
local.format.endpage | 8097 | en |
local.identifier.scopusid | 20444413845 | en |
local.peerreviewed | Yes | en |
local.identifier.volume | 127 | en |
local.identifier.issue | 22 | en |
local.title.subtitle | Limitations of Aryloxenium Ion Chemistry | en |
local.contributor.lastname | Novak | en |
local.contributor.lastname | Glover | en |
dc.identifier.staff | une-id:sglover | en |
local.profile.orcid | 0000-0002-9344-8669 | en |
local.profile.role | author | en |
local.profile.role | author | en |
local.identifier.unepublicationid | une:552 | en |
dc.identifier.academiclevel | Academic | en |
local.title.maintitle | The Hydrolysis of 4-acyloxy-4-substituted-2,5-cyclohexadienones | en |
local.output.categorydescription | C1 Refereed Article in a Scholarly Journal | en |
local.search.author | Novak, M | en |
local.search.author | Glover, S | en |
local.uneassociation | Unknown | en |
local.identifier.wosid | 000229619500045 | en |
local.year.published | 2005 | en |
Appears in Collections: | Journal Article School of Science and Technology |
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