Efficient supercritical carbon dioxide promoted reductive amination of furfural using water as hydrogen donor over Ni/CaCO3

Herein, we reported an environment-friendly supercritical carbon dioxide (SCD) system for the reductive amination of furan aldehydes to amine using water/Zn as hydrogen donor. A 91% yield of furfuryl amine was obtained at 80 °C over Ni/CaCO3. The study of the hydrogen supply mechanism suggested that SCD effectively reduced the potential of water splitting to provide active hydrogen by the reaction of Zn with the self-neutralizing in situ acid from H2O and CO2. The supported Ni/CaCO3 characterized by extraordinary stability and high dispersity exhibited the high selectivity to furfuryl amine. This protocol also performed well for the reductive amination of a serial of aldehydes and amines. More importantly, this system also exhibited excellent reduction performance for reducing the derivatives related to furfural and 5-hydroxylmethyl furfural.