Phosphotungstic anions-based imidazolium porous ionic polymer for oxidation of alcohols with hydrogen peroxide

An imidazolium-based hyper-crosslinked porous ionic polymer (IHPiP) immobilized phosphotungstic (PW) anions hybrid catalyst (IHPiP-PW) was synthesized based on a one-pot Friedel–Crafts alkylation and quaternization reaction, followed by anion exchange. The obtained IHPiP-PW exhibited a high specific surface area of 615 m² g⁻¹ containing plentiful hierarchical pores. IHPiP-PW was effective in the oxidation of 1-phenylethanol into acetophenone with H₂O₂ to give a high conversion of 95.7 % and quantitative selectivity. A remarkable turnover number of 3300 and initial turnover frequency of 914.0 h⁻¹ were obtained at a substrate/PW molar ratio of 4000. Kinetic study demonstrated that 1-phenylethanol oxidation obeyed pseudo-first-order kinetics and the apparent activation energy was calculated to be 26.116 kJ mol⁻¹. This catalytic system was tolerant of a wide range of substrates. Moreover, IHPiP-PW could be readily recovered and effectively reused for six cycles without significant catalytic activity loss.