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Understanding the Regioselectivity of Aromatic Hydroxylation over Divanadium-Substituted ¿-Keggin Polyoxotungstate

  • Datos identificativos

    Identificador: PC:3144
    Autores:
    Ricart, J. M.Skobelev, IEvtushok, V.Kholdeeva, O.Maksimchuk, N.Maksimovskaya, R.Poblet, J. M.Carbó, J.
    Resumen:
    Filiació URV: SI
  • Otros:

    Autor según el artículo: Ricart, J. M. ; Skobelev, I; Evtushok, V. ; Kholdeeva, O.; Maksimchuk, N. ; Maksimovskaya, R. ; Poblet, J. M.; Carbó, J.
    Departamento: Química Física i Inorgànica
    Autor/es de la URV: RICART PLA, JOSE MANUEL; Skobelev, I; Evtushok, V. ; Kholdeeva, O.; Maksimchuk, N. ; Maksimovskaya, R. ; POBLET RIUS, JOSEP MARIA; CARBÓ MARTIN, JORGE JUAN
    Palabras clave: homogeneous catalysis DFT aromatic hydroxylation
    Resumen: The aromatic hydroxylation of pseudocumene (PC) with aqueous hydrogen peroxide catalyzed by the divanadium-substituted γ-Keggin polyoxotungstate TBA4[γ-PW10O38V2(μ-O)(μ-OH)] (TBA-1H, TBA = tetrabutylammonium) has been studied using kinetic modeling and DFT calculations. This reaction features high chemoselectivity and unusual regioselectivity, affording 2,4,5-trimethylphenol (TMP) as the main product. Then the computational study was extended to the analysis of the regioselectivity for other alkoxy- and alkylarene substrates. The protonation/deprotonation of TBA-1H in MeCN/tBuOH (1:1) was investigated by 31P NMR spectroscopy. Forms with different protonation states, [γ-PV2W10O40]5– (1), [γ-HPV2W10O40]4– (1H), and [γ-H2PV2W10O40]3– (1H2), have been identified, and the protonation equilibrium constants were estimated on the basis of the 31P NMR data. DFT calculations were used to investigate the oxygen transfer process from hydroperoxo species, [γ-PW10O38V2(μ-O)(μ-OOH)]4– (2) and [γ-PW10O38V2(μ-OH)(μ-OOH)]3– (2H), and peroxo complex [γ-PW10O38V2(μ-η2:η2-O2)]3– (3) toward the different positions in the aromatic ring of PC, anisole, and toluene substrates. Product, kinetic, and computational studies on the PC hydroxylation strongly support a mechanism of electrophilic oxygen atom transfer from peroxo complex 3 to the aromatic ring of PC. The kinetic modeling revealed that the contribution of 3 into the initial reaction rate is, on average, about 70%, but it may depend on the reaction conditions. DFT calculations showed that the steric hindrance exerted by peroxo complex 3 is responsible for the origin of the unusual regioselectivity observed in PC hydroxylation, while for anisole and toluene the regioselective para-hydroxylation is due to electronic preference during the oxygen transfer from the active peroxo species
    Grupo de investigación: Química Quàntica
    Áreas temáticas: Chemistry Química Química
    Acceso a la licencia de uso: https://creativecommons.org/licenses/by/3.0/es/
    ISSN: 2155-5435
    Identificador del autor: 0000-0002-2610-5535; ; ; ; ; ; 0000-0002-4533-0623; 0000-0002-3945-6721
    Fecha de alta del registro: 2018-03-05
    Página final: 8523
    Volumen de revista: 7
    Versión del articulo depositado: info:eu-repo/semantics/submittedVersion
    Enlace a la fuente original: https://pubs.acs.org/doi/abs/10.1021/acscatal.7b02694
    Programa de financiación: altres; Grupos Consolidados; 2014SGR199 plan; Excelencia; CTQ2014-52774-P
    URL Documento de licencia: https://repositori.urv.cat/ca/proteccio-de-dades/
    DOI del artículo: 10.1021/acscatal.7b02694
    Entidad: Universitat Rovira i Virgili
    Año de publicación de la revista: 2017
    Página inicial: 8514
    Tipo de publicación: Article Artículo Article
  • Palabras clave:

    Catàlisi homogènia
    Funcional de densitat, Teoria del
    homogeneous catalysis
    DFT
    aromatic hydroxylation
    Chemistry
    Química
    Química
    2155-5435
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