Hyperbranched aromatic poly(ether ketone) functionalized with TEMPO as a heterogeneous catalyst for aerobic oxidation of alcohols

Abstract

A hyperbranched aromatic poly(ether ketone) functionalized with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO/HBPEK) was investigated as a novel heterogeneous catalyst for aerobic oxidation of alcohols. The TEMPO/HBPEK contained 2 mmol g⁻¹ TEMPO and had a turnover number (TON) of 46 compared to commercial TEMPO with a TON of 60, indicating good catalytic activity and selectivity for the aerobic oxidation of benzyl alcohol. This material can be used as a recyclable heterogeneous catalyst by grafting it onto insoluble supports such as carbon black (TEMPO/HBPEK/CB) or polyimide nanoparticles (TEMPO/HBPEK/PI), whereas the bare TEMPO/HBPEK acts as a homogeneous catalyst. These heterogeneous catalysts had TONs of 27 and 22, respectively, indicating greater catalytic activity than the commercially available heterogeneous catalyst, TEMPO immobilized on polystyrene, which had a TON less than 1.