Towards Improved Biorefinery Technologies: 5‐Methylfurfural as a Versatile C₆ Platform for Biofuels Development

Abstract

Low chemical stability and high oxygen content limit utilization of the bio‐based platform chemical 5‐(hydroxymethyl)furfural (HMF) in biofuels development. In this work, Lewis‐acid‐catalyzed conversion of renewable 6‐deoxy sugars leading to formation of more stable 5‐methylfurfural (MF) is carried out with high selectivity. Besides its higher stability, MF is a deoxygenated analogue of HMF with increased C/O ratio. A highly selective synthesis of the innovative liquid biofuel 2,5‐dimethylfuran starting from MF under mild conditions is described. The superior synthetic utility of MF against HMF in benzoin and aldol condensation reactions leading to long‐chain alkane precursors is demonstrated.

Rapid, High‐Yield Fructose Dehydration to 5‐Hydroxymethylfurfural in Mixtures of Water and the Noncoordinating Ionic Liquid [bmim][OTf]

“…The stability of HMF has provenakey issue for the effective valorization of the dehydration reaction. [53] As olvents ystem capable of stabilizing HMF is neededt oi mprove the yield of reactiona nd to avoid self-condensation of HMF over longer reaction times. Water has the potential to act as ah ydrogen bond acceptor, contributing to the stabilization to HMF.…”

When Will 5‐Hydroxymethylfurfural, the “Sleeping Giant” of Sustainable Chemistry, Awaken?

“…Although biofuels do not need to be identical to fossil fuels, the most significant developments have occurred in the production of biofuel candidates compatible with traditional combustion engines for use as an additive or as a substitute . Although HMF has better energy characteristics than those of carbohydrates, its utilization as a biofuel is insufficient due to its high boiling point, high oxygen content, relative chemical instability, and insolubility in hydrocarbons . To access more suitable liquid biofuels, further deoxygenation of HMF by catalytic hydrodeoxygenation or other chemical modifications of HMF are required.…”

“… Regarding drop‐in biorefining, efficient HMF‐based access to bioaromatics may rely on the connection of HMF with furfural chemistry (e.g., by decarbonylation) because furfural derivatives are clearly more suitable for the synthesis of diverse aromatics by [4+2] cycloadditions. Further development of the direct recyclization of furanic derivatives to obtain common arene‐type systems may also be important. To overcome the problem of HMF instability, the conversion of C 6 ‐modified carbohydrates, leading to appropriateO‐modified HMF derivatives, without the formation of unstable HMF as an intermediate may be used . This process usually proceeds with higher selectivity than that of the conversion of unmodified carbohydrates into HMF due to blocking of side processes associated with the presence of reactive hydroxymethyl groups.…”

“…O‐modified HMF derivatives, without the formation of unstable HMF as an intermediate may be used . This process usually proceeds with higher selectivity than that of the conversion of unmodified carbohydrates into HMF due to blocking of side processes associated with the presence of reactive hydroxymethyl groups.…”

The Increasing Value of Biomass: Moving From C6 Carbohydrates to Multifunctionalized Building Blocks via 5‐(hydroxymethyl)furfural

“…The use of carbohydrates modified at the C6 hydroxyl group leads to significant increase in selectivity of the conversion process due to the direct formation of the C6 furanic derivatives without unstable HMF as an intermediate (Scheme 1). [7c,d,10] Another problem is the high oxygen content of the HMF molecule, which complicates its isolation and purification. These obstacles impede the full‐fledged industrial production of the HMF‐derived products.…”