Mechanism of the Aerobic Oxidation of Alcohols by Palladium Complexes of N-Heterocyclic Carbenes.
Quantum mechanics (B3LYP density functional theory) combined with solvation (Poisson-Boltzmann polarizable continuum solvent model) was used to investigate six mechanisms for the aerobic oxidation of alcohols catalyzed by (NHC)Pd(carboxylate)(HO) complexes (NHC = 1,3-bis(2,6-diisopropylphenyl)imidaz...
| Publicado en: | Journal of the American Chemical Society Vol. 128; no. 30; pp. 9651 - 9661 |
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| Autores principales: | , |
| Formato: | Artículo |
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American Chemical Society
8/2/2006
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=21862000&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 21862000 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 8/2/2006 vid: 128 iid: 30 pid: 997 pub: American Chemical Society artinfo: ui: 21862000 10.1021/ja060915z ppf: 9651 ppct: 10 formats: tig: atl: Mechanism of the Aerobic Oxidation of Alcohols by Palladium Complexes of N-Heterocyclic Carbenes. aug: au: Nielsen, Robert J. Goddard III, William A. affil: Materials and Process Simulation Center, Beckman Institute (139-74), Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125 su: Quantum theory Density functionals Solvation Oxidation Alcohols (Chemical class) Alkoxides Isotope shift Acetic acid Palladium Mathematical complexes sug: subj: Quantum theory Density functionals Solvation Oxidation Alcohols (Chemical class) Alkoxides Isotope shift Acetic acid Palladium Mathematical complexes ab: Quantum mechanics (B3LYP density functional theory) combined with solvation (Poisson-Boltzmann polarizable continuum solvent model) was used to investigate six mechanisms for the aerobic oxidation of alcohols catalyzed by (NHC)Pd(carboxylate)(HO) complexes (NHC = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene). Of these, we find that ‘reductive β-hydride elimination’, in which the β-hydrogen of a palladium-bound alkoxide is transferred directly to the free oxygen of the bound carboxylate, provides the lowest-energy route and explains the published kinetic isotope effect, activation enthalpy, reaction orders, and dependence of rate on carboxylate pK. The traditional β-hydride elimination mechanism cannot be responsible for the experimentally observed kinetic parameters, which we find could result from the subsequent reductive elimination of acetic acid, which yields a slightly higher calculated activation barrier. Reversible β-hydride elimination may provide a mechanism for the racemization of chiral alcohols, which would undermine attempts at an enantioselective oxidation. Competition among these pathways can be influenced by changing the electronic properties of the carboxylate and substrate. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2006 holdings: @attributes: islocal: N |
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