Epoxidation of styrene to styrene oxide using carbon dioxide and hydrogen peroxide in ionic liquids

The epoxidation of styrene using hydrogen peroxide and compressed CO2 was conducted in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), 1-butyl-3-methylimidazolium hexafluoroborate ([bmim][PF6]), 1-butyl-3-methylimidazolium chloride ([bmim]Cl), 1,1,3,3-tetramethylguanidinium lactate [TMG][Lac], 1,1,3,3-tetramethylguanidinium trifluoroacetate [TMG][CF3COO], ethanol, and acetonitrile. It was demonstrated that the reaction could be carried out effectively in [bmim][BF4] or [bmim]Cl without any metallic catalysts. HCO4− produced from CO2 and H2O2 acted as the catalyst. The conversion of styrene and the yield of styrene oxide could reach 95% and 69%, respectively.

Graphical abstractEpoxidation of styrene to styrene oxide using carbon dioxide and hydrogen peroxide in ionic liquids was studied. The various reaction parameters in the epoxidation of styrene were investigated. The pressure of CO2, equivalents of KOH and H2O2, reaction time and different ionic liquids had influence on the conversion of styrene and the yield of styrene oxide. Figure optionsDownload full-size imageDownload as PowerPoint slide