Continuous reductive amination of carbonyl compounds with ammonia to synthesize secondary amines with high selectivity

Secondary amines are important compounds in the field of drug development. Applying reductive amination can conveniently synthesize secondary amines from carbonyl compounds. In this work, we propose an economical method for selective synthesis of secondary amines by using ammonia as a nitrogen source. A promising Pt/SiO2 (Pt loading 1 wt%) catalyst was designed for the continuous reductive amination of benzaldehyde (benchmark reaction), and effects of catalyst, solvent, temperature, the molar ratio of ammonia to benzaldehyde, pressure, concentration, liquid flow rate and gas flow rate are investigated. With the optimal reaction conditions, a high yield of dibenzylamine (95.5%) is obtained under very mild reaction temperature (30 celcius) and extremely short reaction times. Furthermore, a kinetic model for the formation of dibenzylamine is established, and corresponding kinetic parameters are obtained. Besides, many substrates, including aromatic aldehydes, biomass derivative furfural and even ketone, can all be smoothly converted into secondary amines.