Amphiphilic Mesoporous Poly(Ionic Liquid) Immobilized Heteropolyanions Towards the Efficient Heterogeneous Epoxidation of Alkenes with Stoichiometric Hydrogen Peroxide

Novel mesoporous poly(ionic liquid)s (MPILs) featuring pure polycationic framework and tunable hydrophobicity were synthesized through the free radical polymerization of alkyl-functionalized ionic liquids (ILs) and bis-vinylimidazolium salt. Phosphotungstic (PW) anions were firmly immobilized on these MPILs with high dispersion and density. The obtained catalyst was effective in the epoxidation of cis-cyclooctene with stoichiometric H₂O₂, rendering the high yield (>98%) and remarkable H₂O₂ efficiency (>98%). The maximum turnover number (TON) and turnover frequency (TOF) arrived at 2375 and 685 h-1, respectively. The catalyst can be facilely recovered by filtration and reused with stable activity. Various other alkenes can be also converted with high yields. The extraordinary performance was attributable to the pure ionic porous framework with enhanced hydrophobicity that not only provides strong cation-anion interaction towards the stable immobilized PW anions with high dispersion, but also enables the strong affinity of the catalyst with both the substrate and oxidant.