Kinetics of Epoxidation of Cyclooctene with Ionic Liquids Containing Tungstate as Micellar Catalyst

The kinetics of cyclooctene epoxidation with H₂O₂ by micellar catalysis was studied. As catalyst, an ionic liquid (IL) containing the catalytically active tungstate anion was used. The tungstate IL forms micelles in the aqueous H₂O₂ phase. It is simply formed by dissolving sodium tungstate and 1-octyl-3-methylimidazolium tetrafluoroborate [OMIM][BF₄] in aqueous H₂O₂. For the epoxidation of cyclooctene by micellar catalysis, a power law kinetic model was determined that takes the critical micelle concentration into account. The kinetics of the [OMIM][BF₄]/Na₂WO₄ catalyst is similar to pure [OMIM]₂[WO₄], which indicates that the active species is formed in situ. Addition of phenylphosphonic acid improves the activity of the tungstate IL. The most effective catalyst was tested in a semi-continuous and continuous loop reactor.