A competing, dual mechanism for catalytic direct benzene hydroxylation from combined experimental-DFT studies

A dual mechanism for direct benzene catalytic hydroxylation is described. Experimental studies and DFT calculations have provided a mechanistic explanation for the acid-free, Tp x Cu-catalyzed hydroxylation of benzene with hydrogen peroxide (Tp x = hydrotrispyrazolylborate ligand). In contrast with...

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Veröffentlicht in:Chemical science (Cambridge) 2017, Vol.8 (12), p.8373-8383
Hauptverfasser: Vilella, Laia, Conde, Ana, Balcells, David, Díaz-Requejo, M. Mar, Lledós, Agustí, Pérez, Pedro J
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Sprache:eng
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Zusammenfassung:A dual mechanism for direct benzene catalytic hydroxylation is described. Experimental studies and DFT calculations have provided a mechanistic explanation for the acid-free, Tp x Cu-catalyzed hydroxylation of benzene with hydrogen peroxide (Tp x = hydrotrispyrazolylborate ligand). In contrast with other catalytic systems that promote this transformation through Fenton-like pathways, this system operates through a copper-oxyl intermediate that may interact with the arene ring following two different, competitive routes: (a) electrophilic aromatic substitution, with the copper-oxyl species acting as the formal electrophile, and (b) the so-called rebound mechanism, in which the hydrogen is abstracted by the Cu-O moiety prior to the C-O bond formation. Both pathways contribute to the global transformation albeit to different extents, the electrophilic substitution route seeming to be largely favoured. A dual mechanism for direct benzene catalytic hydroxylation is described.
ISSN:2041-6520
2041-6539
DOI:10.1039/c7sc02898a