[γ-1,2-H2SiV2W10O40] immobilized on surface-modified SiO2 as a heterogeneous catalyst for liquid-phase oxidation with H2O2

Jun Kasai, Yoshinao Nakagawa, Sayaka Uchida, Kazuya Yamaguchi, Noritaka Mizuno

Research output: Contribution to journalArticlepeer-review

128 Citations (Scopus)

Abstract

An organic-inorganic hybrid support has been synthesized by covalently anchoring an N-octyldihydroimidazolium cation fragment onto SiO2 (denoted as 1-SiO2). This modified support was characterized by solid-state 13C, 29Si, and 31P NMR spectroscopy, IR spectroscopy, and elemental analysis. The results showed that the structure of the dihydroimidazolium skeleton is preserved on the surface of SiO2. The modified support can act as a good anion exchanger, which allows the catalytically active polyoxometalate anion [γ-1,2-H 2SiV2W10O40]4- (I) to be immobilized onto the support by a stoichiometric anion exchange (denoted as I/1-SiO2). The structure of anion I is preserved after the anion exchange, as confirmed by IR and 51V NMR spectroscopy. The catalytic performance for the oxidation of olefins and sulfides, with hydrogen peroxide (only one equivalent with respect to substrate) as the sole oxidant, was investigated with I/1-SiO2. This supported catalyst shows a high stereospecificity, diastereoselectivity, regioselectivity, and a high efficiency of hydrogen peroxide utilization for the oxidation of various olefins and sulfides without any loss of the intrinsic catalytic nature of the corresponding homogeneous analogue of I (i.e., the tetra-n-butylammonium salt of I, TBA-I), although the rates decreased to about half that with TBA-I. The oxidation can be stopped immediately by removal of the solid catalyst, and vanadium and tungsten species' can hardly be found in the filtrate after removal of the catalyst. These results rule out any contribution to the observed catalysis from vanadium and tungsten species that leach into the reaction solution, which means that the observed catalysis is truly heterogeneous in nature. In addition, the catalyst is reusable for both epoxidation and sulfoxidation without any loss of catalytic performance.

Original languageEnglish
Pages (from-to)4176-4184
Number of pages9
JournalChemistry - A European Journal
Volume12
Issue number15
DOIs
Publication statusPublished - 2006 May 15
Externally publishedYes

Keywords

  • Green chemistry
  • Heterogeneous catalysis
  • Hydrogen peroxide
  • Immobilization
  • Oxidation
  • Polyoxometalates

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

Fingerprint Dive into the research topics of '[γ-1,2-H<sub>2</sub>SiV<sub>2</sub>W<sub>10</sub>O<sub>40</sub>] immobilized on surface-modified SiO<sub>2</sub> as a heterogeneous catalyst for liquid-phase oxidation with H<sub>2</sub>O<sub>2</sub>'. Together they form a unique fingerprint.

Cite this