Main > GREEN CHEMISTRY > Epoxides > Co.: JA. N (Tungstate-H2O2/Patent) > NPLS Contents
A promising hydrogen peroxide-based system formulated by a team of Japanese researchers converts a wide range of linear and cyclic olefins to epoxides with high selectivity and maximum H2O2 efficiency.
Cleaner oxidations using H2O2 have been an important target for industrial synthesis of epoxides, which are used as monomers and chiral intermediates. The use of H2O2 is an advance over more expensive organic peroxides and peracids or environmentally unfavored chlorine-based oxidations. Water is typically the sole by-product.
AUTHOR, screened silicotungstate catalysts for their ability to aid activation of H2O2 to form reactive oxygen species. The ammonium salt of the novel polyoxometallate cluster [-SiW10O34(H2O)2]4– provided the highest catalytic activity, they note. It allows conversion of olefins to the corresponding epoxides in acetonitrile at 32 °C with most yields above 90% and essentially 100% selectivity and 100% H2O2 utilization.
The homogeneous catalyst can be recovered by evaporating the solvent to dryness and washing with n-hexane. It can be used at least five times without loss of performance or degradation to other tungsten compounds.
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