Development of a heterogeneous cis-dihydroxylation process with hydrogen peroxide as oxidant
The development of a successful heterogeneous cis-dihydroxylation process, using a heterogenized Os-catalyst and H2O2 as oxidant, is reported. In the described method, OsVI is reoxidized to OsVIII by N-methylmorpholine N-oxide (NMO), which is only present in catalytic amounts; NMO is regenerated from N-methylmorpholine (NMM) by oxidation with H2O2, which is used as a stoichiometric oxidant. To maintain the heterogeneous nature of the Os catalysis, it is necessary to perform the cis-dihydroxylation reaction and the regeneration of NMO in two physically separated vessels. A two batch system, with discontinuous circulation of the liquid between the NMO regeneration vessel and the dihydroxylation vessel, was designed. For the oxidation of NMM, two different heterogeneous catalysts, namely Ti-MCM-41 and LDH-WO42− (tungstate exchanged layered double hydroxide) are used, both with satisfying results. This innovative system is one of the first attempts to perform heterogeneous cis-dihydroxylation reactions with the ecologically friendly oxidant H2O2.