CeCl 3 ‐ N ‐Hydroxyphthalimide Complex as Semi‐Heterogeneous Photocatalyst for Selective Oxidation of Toluene to Benzaldehyde

ABSTRACT The activation of inert C(sp 3 )‐H bonds is the rate‐determining step in photocatalytic selective oxidation of toluene, and the easy over‐oxidation of target products makes it a great challenge in green organic synthesis. Herein, we report a semi‐heterogeneous CeCl x ‐NHPI complex, which is constructed via the coordination of CeCl 3 and N‐Hydroxyphthalimide (NHPI) for the efficient visible‐light‐driven selective oxidation of toluene to benzaldehyde under ambient conditions. Impressively, the catalyst achieved a maximum benzaldehyde formation rate of up to 2 mmol·g −1 ·h −1 in 5 h, with a benzaldehyde selectivity of 80.6%. Mechanistic studies show that the chlorine radicals (Cl·) generated from the coordinated Ce─Cl bond via the ligand‐to‐metal charge transfer (LMCT) process, and the phthalimide‐N‐oxyl (PINO) radicals formed from NHPI via single‐electron transfer jointly promote the efficient activation of the inert C(sp 3 )‐H bond in toluene. In addition, the CeCl x ‐NHPI complex exhibits good recyclability and broad substrate tolerance for the selective oxidation of various toluene derivatives. This work provides a novel strategy for the design of efficient rare earth‐based semi‐heterogeneous photocatalysts for the activation of C(sp 3 )‐H bonds.