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Continuous reductive amination to synthesize primary/secondary amines with high selectivity in flow
Jiahao Zhang, Doctoral students in Tsinghua University (Beijing, China), The state key laboratory of Chemical Engineering, Department of Chemical Engineering, Tsinghua University
Reductive amination is a convenient way to synthesize amines from carbonyl compounds. It has attracted widespread attention in amine production due to its wide range of substrates, easy availability of raw materials, and only water as a theoretical byproduct. In this work, we propose a continuous reductive amination process in a micropacked bed reactor to synthesize primary/secondary amines with high selectivity. The reductive amination of benzaldehyde is chosen as the model reaction to elucidate the effects of catalyst/support, solvent, temperature, the molar ratio of ammonia to benzaldehyde, pressure, concentration, liquid flow rate, and gas flow rate. Finally, a high 99% yield of benzylamine/95.5% yield of dibenzylamine is obtained under mild conditions, low catalyst cost, and shorter reaction time. Furthermore, kinetic networks are established for the reductive amination to generate benzylamine and dibenzylamine, respectively, and corresponding rate-determining steps are determined. Besides, satisfied yields are also obtained when applying this method to various substrates, including aromatic and aliphatic aldehydes, ketones, and biomass derivative furfural.
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