Pd/SiC-Catalyzed Visible-Light-Driven N-Methylation of Nitroaranes Using Formaldehyde

Pd nanoparticles (Pd/SiC) with a main exposed plane of Pd (111) were prepared by liquid phase reduction. The use of formaldehyde as a methylation reagent for the photocatalytic methylation of aromatic nitro compounds to N,N-methylaniline resulted in one-pot methylations of aromatic nitro compounds with high photocatalytic activity and selectivity under mild reaction conditions. The high catalytic activity of Pd/SiC in N-methylation reactions arises from the Mott-Schottky contact between Pd and SiC, which promotes the transfer of photogenerated electrons to Pd. The high selectivity is ascribed to the ability of Pd nanoparticles to catalyze the hydrogenation of nitro groups to amino groups, which subsequently undergo direct methylation with formaldehyde, bypassing the intermediate formylation step.