Sustainable access to renewable N-containing chemicals from reductive amination of biomass-derived platform compounds

Abstract

Nitrogen-containing compounds are pivotal building blocks with extensive application in the manufacture of pharmaceuticals, polymer materials, agrochemicals and organic synthesis. The sustainable production of nitrogen-containing compounds from renewable biomass derivatives...

Selective Catalysis for the Reductive Amination of Furfural Towards Furfurylamine by the Graphene-Co-Shelled Cobalt Nanoparticles

“…The hydrogenation of N-furfurylidenefurfurylamine could easily produce the by-product of Difurfurylamine (i.e., 1c), while its subsequent thermal cyclization to furfurin (i.e., 1d) has also been noted in previous works 39 . Interestingly, the hydrogenation of furfural into furfuryl alcohol was not detected in our catalyst system, which was commonly observed in other catalytic systems, especially using noble metal catalyst 6 . This might be caused by the fact that the cobalt-based catalysts were inactive towards the hydrogenation of furfuryl alcohol, in accordance with the higher selectivity towards furfurylamine in Raney Co system when compared to that of Raney Ni (Entry 10,11).…”

“…After selecting the suitable catalyst and the optimized reaction conditions from benchmark reaction, we next explored the substrate scope of catalyst in converting a wide range of biomass-derived platforms for the synthesis of primary amines via reductive amination, which can easily be functionalized further and thus serve as central building blocks for fine chemicals or pharmaceutical drugs 6 . As can be seen from Fig.…”

“…In this regard, lignocellulosic biomass stands out as a promising renewable carbon source for chemical industry because of its advantages on abundant reserves, eco-friendliness, and worldwide distribution [3][4][5] . As we already known, the transformation of lignocellulosic components (i.e., hemicellulose, cellulose, and lignin) into small organic intermediates, namely platform molecules, is the essential precursors to progress towards the synthesis of fine chemicals, drop-in biofuels, and biodegradable materials 6 . So far, a variety of platform molecules, including but not limited to furfural, 5-hydroxymethyfurfural (5-HMF), levulic acid and phenol (or phenol derives), can be easily obtained from lignocellulosic biomass, which can be used as substitutes for fossil-based feedstock in the manufacture of valuable compounds, especially in the field of fine chemicals [7][8][9] .…”

“…It is worthwhile that there are still minor mechanistic details under debate surrounding the condensation reaction in step B, which was discussed extensively in a thorough review by Gomez et al 15 Once the secondary imine is formed, it was easily hydrogenated to the secondary amine (step C) that can be further condensed with furfurylamine as step B, or it can be decomposed to the primary imine (or amine) in the presence of ammonia (step D). And also, the primary imine can also be hydrogenated to the target amine in step E. Unfavorable side reactions involve the formation of difurfurylamine and furfuryl alcohol competing with the formation of furfurylamine rendering the selectivity synthesis of furfurylamine challenging 6 . This was further corroborated by Hara et al 16 by means of density functional theory (DFT) calculations, suggesting that the formation of difurfurylamine and furfuryl alcohol was more thermodynamically favorable relative to the formation of furfurylamine.…”

“…Ebitani and co-workers 19 indicated that the Ru-based catalyst supported by hydroxyapatite (Ru-PVP/HAP) facilitated reductive amination of furfural and afforded a relatively lower yield of furfurylamine at 60 %, similar with other Ru-based oxide-supported catalyst reported by Chatterjee et al 14 and Komanoya et al 16 The unfavorable side reactions included the formation of difurfurylamine and furfuryl alcohol are the major reaction which challenges the reductive amination of furfural, while Martinez et al 20 found that screening and adjusting the structural features of supports is beneficial for selectivity synthesis owing to the synergistic effect of acid sites and metal sites. On another hands, the expensive and scarcity of noble metal-based catalysts arise negative effects on the production cost as well as its large-scale application, which motivates the low-cost and abundant non-noble metal-based catalysts for the reductive amination of furfural 6 . Xu and co-workers 21 indicated that both of the commercial Raney Ni and Raney Co enabled the reductive amination of furfural with ammonia to proceed well, but the latter was proved to be superior to the former in terms of higher selectivity towards furfurylamine as the metallic cobalt facilitates hydrogenolysis of N-furfurylidenefurfurylamine.…”