Alumina: a cheap, active and selective catalyst for epoxidations with (aqueous) hydrogen peroxide

Chromatography alumina catalyses the epoxidation of alkenes with hydrogen peroxide under nearly anhydrous conditions. A variety of different aluminas show a similar catalytic behaviour. The hydrogen peroxide can be used as a preformed anhydrous solution in ethyl acetate, or it can be dried in situ by conducting the reaction under reflux with Dean-Stark water separation. The presence of a small amount of water in the reaction medium was shown to be of crucial importance.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.3524324

Vanadium-catalyzed, microwave-assisted oxidations with H2O2 in ionic liquids

The application of vanadium(V) catalysts in selective oxidation with peroxides offers an efficient procedure that is compatible with different functional groups and leads to good yields and selectivities. However, the search for more efficient and sustainable procedures that employ H2O2 as oxidant remains an important topic. In the last few years, striking results have been obtained by applying microwave (MW) activation in metal-catalyzed reactions carried out in ionic liquids (ILs). In the present study, results achieved with vanadium-based catalysts in oxidations of various substrates with H2O2 are presented; in particular, epoxidation of alkenes and sulfoxidation of thioethers have been investigated. Notably, in the latter oxidation, a significant improvement in the rate of reaction and an increase in selectivity have been observed in the case of hydrophobic ILs in combination with MW activation