Articles producció científica> Química Física i Inorgànica

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

  • Identification data

    Identifier: PC:3144
    Authors:
    Ricart, J. M.Skobelev, IEvtushok, V.Kholdeeva, O.Maksimchuk, N.Maksimovskaya, R.Poblet, J. M.Carbó, J.
    Abstract:
    Filiació URV: SI
  • Others:

    Author, as appears in the article.: Ricart, J. M. ; Skobelev, I; Evtushok, V. ; Kholdeeva, O.; Maksimchuk, N. ; Maksimovskaya, R. ; Poblet, J. M.; Carbó, J.
    Department: Química Física i Inorgànica
    URV's Author/s: RICART PLA, JOSE MANUEL; Skobelev, I; Evtushok, V. ; Kholdeeva, O.; Maksimchuk, N. ; Maksimovskaya, R. ; POBLET RIUS, JOSEP MARIA; CARBÓ MARTIN, JORGE JUAN
    Keywords: homogeneous catalysis DFT aromatic hydroxylation
    Abstract: 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
    Research group: Química Quàntica
    Thematic Areas: Chemistry Química Química
    licence for use: https://creativecommons.org/licenses/by/3.0/es/
    ISSN: 2155-5435
    Author identifier: 0000-0002-2610-5535; ; ; ; ; ; 0000-0002-4533-0623; 0000-0002-3945-6721
    Record's date: 2018-03-05
    Last page: 8523
    Journal volume: 7
    Papper version: info:eu-repo/semantics/submittedVersion
    Link to the original source: https://pubs.acs.org/doi/abs/10.1021/acscatal.7b02694
    Funding program: altres; Grupos Consolidados; 2014SGR199 plan; Excelencia; CTQ2014-52774-P
    Licence document URL: https://repositori.urv.cat/ca/proteccio-de-dades/
    Article's DOI: 10.1021/acscatal.7b02694
    Entity: Universitat Rovira i Virgili
    Journal publication year: 2017
    First page: 8514
    Publication Type: Article Artículo Article
  • Keywords:

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