Polyaniline-Grafted VO(acac)2: An Effective Catalyst for the Synthesis of 2,5-Diformylfuran from 5-Hydroxymethylfurfural and Fructose

Recent Approaches in the Catalytic Transformation of Biomass-Derived 5-Hydroxymethylfurfural into 2,5-Diformylfuran

The conversion of biomass into a great variety of valuable chemicals, polymers, and fuels gives a sustainable alternative for the insufficiency of non-renewable fossil fuel resources and reduces environmental pollution. 5-Hydroxymethylfurfural (HMF), converted from sustainable carbohydrates, is a significant building block chemical, and the selective oxidation of HMF into 2,5-diformylfuran (DFF) presents an ongoing challenge. DFF is a versatile platform molecule derived from biomass and has promising application in pharmaceuticals and polymers. This Review provides an overview of the latest developments of efficient catalytic systems for the sustainable conversion of HMF to DFF.

Hydroxyapatite-Supported Polyoxometalates for the Highly Selective Aerobic Oxidation of 5-Hydroxymethylfurfural or Glucose to 2,5-Diformylfuran under Atmospheric Pressure

(NH4 )5 H6 PV8 Mo4 O40 supported on hydroxyapatite (HAP) (PMo4 V8 /HAP (n)) was prepared through the ion exchange of hydroxy groups. This ion exchange favored the oxidative conversion of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF) in a one-pot cascade reaction with 96.0 % conversion and 83.8 % yield under 10 mL/min of O2 flow. PMo4 V8 /HAP (31) was used to explore the production of DFF directly from glucose with the highest yield of 47.9 % so far under atmospheric oxygen, whereas the yield of DFF increased to 54.7 % in a one-pot and two-step reaction. These results indicated that the active sites in PMo4 V8 /HAP (31) retained their activities without any interference toward one another, which enabled the production of DFF in a more cost-saving way by only using oxygen and one catalyst in a one-step reaction. Meanwhile, the rigid structure of HAP and strong interaction in PMo4 V8 /HAP (31) allowed this catalyst to be reused for at least six times with high stability and duration.

The one-step transformation of fructose to 2,5-diformylfuran over Ru metal supported on montmorillonite

Ruthenium metal supported on a montmorillonite (2 wt% Ru-MMT) catalyst have been synthesized and characterized. Catalyst found to be effective for the one-pot transformation of fructose to DFF showing an excellent yield with good recyclability.

Oxidation of lignocellulosic platform molecules to value-added chemicals using heterogeneous catalytic technologies

This minireview gives an overview about heterogeneous catalytic technologies for the oxidation of key platform molecules (glucose, 5-hydroxymethylfurfural, furfural and levulinic acid) into valuable chemicals.

Fabrication of Trifunctional Polyoxometalate-Decorated Chitosan Nanofibers for Selective Production of 2,5-Diformylfuran

Trifunctional catalysts based on polyoxometalate (POM) decorating chitosan nanofibers (H₅ PMo₁₀ V₂ O₄₀ /chitosan nanofibers, abbreviated as HPMoV/CS-f), synthesized by using the electrospinning method, realized highly efficient oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF). Decorating chitosan nanofibers with POMs generated enhanced catalytic activity by merging their unique individual properties of redox ability, Brønsted acidity, basicity, and nanofiber structure with higher surface area. As a result, HPMoV/CS-f(25) (with 25 representing the POM amount) was found to be the most active catalyst in the aerobic oxidation of HMF, resulting in 94.1 % DFF yield at 96.2 % conversion in DMSO at 120 °C for 6 h, whereas 56.2 % DFF yield at 95.0 % conversion was obtained in water at 140 °C for 8 h. Importantly, DFF could be produced in one pot in one step to give 61.9 and 31.4 % yield, respectively, directly from fructose and glucose under the reaction conditions of 140 °C, 6 h in DMSO, which was owing to the suitable balance of Brønsted acidity and basicity of the trifunctional HPMoV/CS-f(25). Moreover, HPMoV/CS-f showed good stability and ability to be reused at least ten times without leaching of the POMs from the chitosan nanofibers.

One-Pot Synthesis of 2,5-Diformylfuran from Fructose by Bifunctional Polyaniline-Supported Heteropolyacid Hybrid Catalysts

We report the preparation of bifunctional hybrid catalysts by supporting H3PMo12O40 (PMo12) heteropolyacid (HPA) on polyaniline (PAN) or formyl-functionalized PAN (F-PAN) for the “one-pot” and “one-step” synthesis of 2,5-diformylfuran (DFF) from fructose via 5-hydroxymethylfurfural (HMF) intermediate. We show that the PMo12 HPA is the main active species for both fructose dehydration and HMF oxidation owing to its Brønsted acidic and redox characters. However, the anchoring of PMo12 on PAN reduces the Brønsted acidity by acid–base interaction between protons in HPA and quinoid diimine structure in PAN, thereby reducing the dehydration performance. We demonstrate that the catalytic dehydration performance of the hybrid catalyst could be strengthened by grafting formyl groups on PAN before HPA anchoring. The highest DFF yield of 76.7% is obtained by conducting the “one-pot” reaction over the 40-PMo12/F3-PAN catalyst at 413 K for 7 h in air, wherein the side-reactions of fructose or HMF degradation and HMF rehydration have been significantly reduced. This hybrid catalyst is reusable without significant activity loss, highlighting the designing of stable inorganic–organic hybrid catalysts for producing valuable hexose-derived platform chemicals.

Recent Advances in the Development of 5-Hydroxymethylfurfural Oxidation with Base (Nonprecious)-Metal-Containing Catalysts

5-Hydroxymethylfurfural (HMF) is one of the versatile platform molecules that can be derived from biomass, and a promising starting substrate for producing 2,5-diformylfuran (DFF) and 2,5-furandicarboxylic acid (FDCA). DFF is a platform chemical with applications in pharmaceuticals, macrocyclic ligands, and functional polymeric materials. Importantly, FDCA is being considered as a potential alternative to replace terephthalic acid for producing the bioplastic polyethylene furanoate, instead of polyethylene terephthalate, by blending with ethylene glycol. A significant number of studies have focused on the oxidation of HMF to FDCA with metal-containing heterogeneous catalysts in both aqueous and organic media in the presence of peroxides/air/molecular oxygen as the oxidant. In this regard, articles have recently been published related to HMF oxidation with base (nonprecious)-metal-containing catalysts that exhibit appealing activity towards DFF or FDCA in terms of yield. Thus, this Minireview focuses on recent developments in efficient transformations of HMF to DFF and FDCA with base-metal-containing heterogeneous catalysts in aqueous and organic media. This review further focuses on the direct transformation of glucose/fructose to DFF and/or FDCA with nonprecious-metal-containing catalysts in various solvents. Photocatalytic approaches for HMF oxidation with nonprecious metal- containing catalysts are also briefly discussed.

Selective Oxidation of 5-(Hydroxymethyl)furfural to DFF Using Water as Solvent and Oxygen as Oxidant with Earth-Crust-Abundant Mixed Oxides

5-Hydroxymethylfurfural (5-HMF) can be considered a prominent building block: because of the presence of the alcohol and aldehyde moieties, it can be used to generate useful molecules as chemicals of industrial interest with high added value, monomers for polymers, and even fuels. This article shows how building up mixed oxides of different complexities and properties may drive the selectivity toward one of the possible products generated from 5-HMF. In particular, mixed oxides based on cerium and other metals abundant on the earth-crust perform the selective oxidation of 5-HMF to 2,5-diformylfuran (94%), using oxygen as oxidant and water as solvent. The roles of the reaction conditions (temperature, reaction time, oxygen pressure, concentration of the substrate), the chemical composition, the acidic/basic properties, and redox properties of the catalysts are discussed.

One-pot tandem conversion of monosaccharides and disaccharides to 2,5-diformylfuran using a Ru nanoparticle-supported H-beta catalyst

Using a one-pot tandem approach, 2,5-diformylfuran is successfully synthesized in high yields from fructose, glucose and sucrose.

Fabrication of mesoporous POMs/SiO2nanofibers through electrospinning for oxidative conversion of biomass by H2O2and oxygen

The oxidation process for mesoporous H₅PMo₁₀V₂O₄₀/SiO₂nanofiber catalyst.

Catalytic oxidation of carbohydrates into organic acids and furan chemicals

A review on the development of new routes for the production of organic acids and furan compoundsviacatalytic oxidation reactions.

Oxidation of 5-Chloromethylfurfural (CMF) to 2,5-Diformylfuran (DFF)

2,5-Diformylfuran (DFF) is an important biorenewable building block, namely for the manufacture of new polymers that may replace existing materials derived from limited fossil fuel resources. The current reported methods for the preparation of DFF are mainly derived from the oxidation of 5-hydroxymethylfurfural (HMF) and, to a lesser extent, directly from fructose. 5-Chloromethylfurfural (CMF) has been considered an alternative to HMF as an intermediate building block due to its advantages regarding stability, polarity, and availability from glucose and cellulose. The only reported method for the transformation of CMF to DFF is restricted to the use of DMSO as the solvent and oxidant. We envisioned that the transformation could be performed using more attractive conditions. To that end, we explored the oxidation of CMF to DFF by screening several oxidants such as H₂O₂, oxone, and pyridine N-oxide (PNO); different heating methods, namely thermal and microwave irradiation (MWI); and also flow conditions. The combination of PNO (4 equiv.) and Cu(OTf)₂ (0.5 equiv.) in acetonitrile was identified as the best system, which lead to the formation of DFF in 54% yield under MWI for 5 min at 160 °C. Consequently, a range of different heterogeneous copper catalysts were tested, which allowed for catalyst reuse. Similar results were also observed under flow conditions using copper immobilized on silica under thermal heating at 160 °C for a residence time of 2.7 min. Finally, HMF and 5,5'-oxybis(5-methylene-2-furaldehyde) (OBMF) were the only byproducts identified under the reaction conditions studied.

Direct Transformation of HMF into 2,5-Diformylfuran and 2,5-Dihydroxymethylfuran without an External Oxidant or Reductant

The selective transformation of 5-hydroxymethylfurfural (HMF) to valuable 2,5-diformylfuran (DFF) and 2,5-dihydroxymethylfuran (DHMF) is highly desirable but remains a great challenge owing to its tendency to over-oxidation and over-reduction. In this work, HMF is directly converted into DFF and DHMF without external oxidant or reductant through a Meerwein-Ponndorf-Verley-Oppenauer (MPVO) reaction. In such a MPVO process, HMF is used as both oxidant and reductant and DFF and DHMF are simultaneously produced with a 1:1 molar ratio in the presence of a Lewis acid catalyst. Under high initial HMF concentration, a HMF conversion of up to 44.7 % can be reached within 1 h. Moreover, this atom-efficient transformation route for HMF also provides a promising protocol for the crude separation of DHMF products from DFF products, owing to the lower solubility of DHMF compared to DFF in acetonitrile.

Nanobelt α-CuV2O6 with hydrophilic mesoporous poly(ionic liquid): a binary catalyst for synthesis of 2,5-diformylfuran from fructose

The task-specific binary catalyst composed of nanobelt α-CuV₂O₆ and hydrophilic mesoporous poly(ionic liquid) exhibited high efficiency and stable activity in the direct synthesis of 2,5-diformylfuran (DFF) from fructose.

One-Pot Conversion of Carbohydrates into Furan Derivatives via Furfural and 5-Hydroxylmethylfurfural as Intermediates

Recently, there has been growing interest in the transformation of renewable biomass into value-added fuels and chemicals. The catalytic conversion of naturally abundant carbohydrates can generate two-important furan chemicals: 5-hydroxymethylfurfural (HMF) from C6 carbohydrates and furfural from C5 carbohydrates. Both HMF and furfural have received great interest as precursors in the synthesis of commodity chemicals and liquid fuels. In recent years, a trend has emerged to integrate sequential catalytic processes involving multistep reactions for the direct one-pot transformation of carbohydrates into the aimed fuels and chemicals. One-pot reactions have remarkably unique and environmentally friendly benefits, including the fact that isolation and purification of intermediate compounds can be avoided. Herein, the present article aims to review recent advances in the one-pot conversion of carbohydrates into furan derivatives via furfural and HMF as intermediates. Special attention will be paid to the catalytic systems, mechanistic insight, reaction pathways, and catalyst stability. It is expected that this review will guide researchers to develop effective catalytic systems for the one-pot transformation of carbohydrates into furan derivatives.

One-pot synthesis of 2,5-diformylfuran from fructose using a magnetic bi-functional catalyst

A magnetic bi-functional WO₃HO-VO(salten)-SiO₂@Fe₃O₄nanocatalyst was prepared to directly synthesize 2,5-diformylfuran (2,5-DFF) from fructose.

Ionic self-assembly affords mesoporous ionic networks by crosslinking linear polyviologens with polyoxometalate clusters

Polyoxometalate-crosslinked mesoporous ionic networks were constructed by ionic self-assembly of linear cationic polyviologens with PMoV clusters, acting as highly efficient heterogeneous catalysts for the conversion of HMF to DFF with ambient O₂.

Simple efficient one-pot synthesis of 5-hydroxymethylfurfural and 2,5-diformylfuran from carbohydrates

A one-pot procedure for the synthesis of DFF starting from mono-, di- or polysaccharides or from primary biomass has been developed. HMF is formed as intermediate and can also be isolated.