Biomass-Derived Single Zn Atom Catalysts: The Multiple Roles of Single Zn Atoms in the Oxidative Cleavage of C–N Bonds

The C–N bond cleavage represents one kind of important organic and biochemical transformation, which has attracted great interest in recent years. The oxidative cleavage of C–N bonds in N,N-dialkylamines into N-alkylamines has been well documented, but it is challenging in the further oxidative cleavage of C–N bonds in N-alkylamines into primary amines due to the thermally unfavorable release of α-position H from N–C_α–H and the paralleling side reactions. Herein, a biomass-derived single Zn atom catalyst (ZnN₄-SAC) was discovered to be a robust heterogeneous non-noble catalyst for the oxidative cleavage of C–N bonds in N-alkylamines with O₂ molecules. Experimental results and DFT calculation revealed that ZnN₄-SAC not only activates O₂ to generate superoxide radicals (·O₂^–) for the oxidation of N-alkylamines to generate imine intermediates (CN), but the single Zn atoms also served as the Lewis acid sites to promote the cleavage of CN bonds in imine intermediates, including the first addition of H₂O to generate α-hydroxylamine intermediates and the following C–N bond cleavage via a H atom transfer process.