Cooperative NHC-based Catalytic System Immobilised onto Carbon Materials for the Cycloaddition of CO2 to Epoxides

New pyrene-tagged imidazolium salts and their corresponding carboxylates were synthesised and the latter tested as organocatalysts in the cycloaddition of CO2 with epoxides. The best performing organocatalyst was then non-covalently immobilised onto carbon materials (carbon nanotubes (CNTs), reduced graphene oxide (rGO) and carbon beads (CBs)) via pi-pi stacking interactions and their activity and recoverability in the cycloaddition reaction were studied. The heterogenised catalyst onto reduced graphene oxide (4 a@rGO) was recycled several times although a loss of activity was observed. This catalyst was also used for the transformation of a series of epoxides under mild conditions.

Automated summary

New pyrene-tagged imidazolium salts and their corresponding carboxylates were synthesized and tested as organocatalysts in the cycloaddition of CO2 with epoxides. The best performing organocatalyst was immobilised onto carbon materials via pi-pi stacking interactions, showing activity and recoverability in the cycloaddition reaction. Despite a loss of activity, the catalyst heterogenised onto reduced graphene oxide was recycled several times and used for the transformation of various epoxides under mild conditions.