Selective hydrogenolysis of bio-renewable tetrahydrofurfurylamine to piperidine on ReOx-modified Rh catalysts

Abstract

Piperidine is an important cyclic amine with versatile applications. However, its commercial process is not green and depends mainly on the hydrogenation of fossil resource-based pyridine. Here, we report a novel one-pot approach to the sustainable synthesis of piperidine from bio-renewable tetrahydrofurfurylamine (THFAM) via its hydrogenolysis to 5-amino-1-pentanol (APO) and the subsequent intramolecular amination of APO. SiO₂-supported Rh–ReO_x catalysts exhibited high efficiency and stability in the THFAM reaction to piperidine, providing a high yield of 91.5% at 200 °C and 2.0 MPa H₂ in water. Such high efficiency of Rh–ReO_x/SiO₂ was found to be related to the synergistic effect between the Rh nanoparticles and ReO_x species on the kinetically-relevant cleavage of the C–O bond neighboring the C–NH₂ group in THFAM, involving the strong adsorption of the C–NH₂ group on ReO_x and the heterolytic dissociation of H₂ on Rh. This work provides an efficient strategy for the selective cleavage of the C–O bonds neighboring the C–NH₂ groups, irrespective of their presence in amino ethers or amino alcohols, and the green production of piperidine and its derivatives from biomass resources.