Aerobic oxidation of benzyl alcohol over TEMPO-functionalized polyimide as a heterogeneous catalyst

Hyperbranched polyimide functionalized with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was studied as a heterogeneous catalyst for the aerobic oxidation of benzyl alcohol. The catalyst material was synthesized by an A(2) + B-3 polymerization of pyromellitic dianhydride and 1,3,5-tris(4-aminophenyl)benzene followed by an end-capping reaction with 4-amino-TEMPO. Selective aerobic oxidation of benzyl alcohol to benzaldehyde has been demonstrated using the prepared materials as a catalyst. The recyclability of these materials has been confirmed by recycling tests using the catalyst collected by filtration.