Heterogeneous Catalyzed Chemoselective Reductive Amination of Halogenated Aromatic Aldehydes

The chemoselective conversion of a specific functional group in a multifunctional substrate is of great importance in the chemical industry to obtain cost efficient, sustainable and waste free processes. This work focuses on the chemoselective amination of halogenated aromatic aldehydes with dimethyl amine towards halogenated aromatic amines, a raw material used in the production of for example agrochemical active ingredients. It was found that by combining palladium, a metal known for dehalogenation reactions, and copper, known for its direct hydrogenation of aldehydes to alcohols, in one heterogeneous bimetallic catalyst, a synergistic effect is obtained. By depositing copper onto a palladium on carbon catalyst with a Cu/Pd ratio of at least 1 : 1, the yield could be increased from 66 % (Pd/C) to 98 % (PdCu/C). Moreover, this highly active and stable catalyst also showed suppressed dehalogenation side-reactions in several other chemical conversions such as hydrogenation of nitro functional groups and hydrogenation of aldehydes.

Automated summary

Utilizing a heterogeneous bimetallic catalyst combining palladium and copper can achieve high yields in chemoselective amination reactions, while also suppressing undesired side reactions in other chemical conversions.