Chemoselective Alkane Oxidation by Superoxo−Vanadium(V) in Vanadosilicate Molecular Sieves

Electron paramagnetic resonance (EPR) spectroscopy of reactive superoxo−vanadium(V) species in vanadosilicate molecular sieves (microporous VS-1 and mesoporous V-MCM-41) generated on contact with H2O2, tert-butyl hydroperoxide (TBHP), or (H2 + O2) is reported for the first time. By suitable choice o...

Full description

Saved in:
Bibliographic Details
Published in:The journal of physical chemistry. B 2006-01, Vol.110 (2), p.677-679
Main Authors: Shetti, Vasudev N, Rani, M. Jansi, Srinivas, D, Ratnasamy, Paul
Format: Article
Language:English
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Electron paramagnetic resonance (EPR) spectroscopy of reactive superoxo−vanadium(V) species in vanadosilicate molecular sieves (microporous VS-1 and mesoporous V-MCM-41) generated on contact with H2O2, tert-butyl hydroperoxide (TBHP), or (H2 + O2) is reported for the first time. By suitable choice of the silicate structure, solvent, and oxidant, we could control the vanadium−(O2 -•) bond (i.e., the V−O bond) covalency, the mode of O−O cleavage (in the superoxo species), and, therefore, chemoselectivity in the oxidation of n-hexane:  Oxidation by TBHP over V-MCM-41, for example, yielded 27.2% of (n-hexanol + n-hexanal + n-hexanoic acid), among the highest chemoselectivities for oxidation of the terminal −CH3 in a linear paraffin reported to date. Over these vanadosilicates, oxidation of the primary C−H bond occurs only via a homolytic O−O bond cleavage; the secondary C−H bond oxidations may proceed via both the homo- and heterolytic O−O cleavage mechanisms.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp0565296