Conversion of 5-hydroxymethylfurfural to furan-2,5-dicarboxylic acid by a simple and metal-free catalytic system

A simple and metal-free catalytic system composed of NaOtBu/DMF and an O2 balloon efficiently converted 5-hydroxymethylfurfural (5-HMF) to furan-2,5-dicarboxylic acid with an 80.85% yield. 5-HMF analogues and various types of alcohols were also transformed to their corresponding acids in satisfactory to excellent yield by this catalytic system.

Advances in Selective Electrochemical Oxidation of 5-Hydroxymethylfurfural to Produce High-Value Chemicals

The conversion of biomass is a favorable alternative to the fossil energy route to solve the energy crisis and environmental pollution. As one of the most versatile platform compounds, 5-hydroxymethylfural (HMF) can be transformed to various value-added chemicals via electrolysis combining with renewable energy. Here, the recent advances in electrochemical oxidation of HMF, from reaction mechanism to reactor design are reviewed. First, the reaction mechanism and pathway are summarized systematically. Second, the parameters easy to be ignored are emphasized and discussed. Then, the electrocatalysts are reviewed comprehensively for different products and the reactors are introduced. Finally, future efforts on exploring reaction mechanism, electrocatalysts, and reactor are prospected. This review provides a deeper understanding of mechanism for electrochemical oxidation of HMF, the design of electrocatalyst and reactor, which is expected to promote the economical and efficient electrochemical conversion of biomass for industrial applications.

Selective Conversion of HMF into 3-Hydroxymethylcyclopentylamine through a One-Pot Cascade Process in Aqueous Phase over Bimetallic NiCo Nanoparticles as Catalyst

5-hydroxymethylfurfural (HMF) has been successfully valorized into 3-hydroxymethylcyclopentylamine through a one-pot cascade process in aqueous phase by coupling the hydrogenative ring-rearrangement of HMF into 3-hydroxymethylcyclopentanone (HCPN) with a subsequent reductive amination with ammonia. Mono- (Ni@C, Co@C) and bimetallic (NiCo@C) nanoparticles with different Ni/Co ratios partially covered by a thin carbon layer were prepared and characterized. Results showed that a NiCo catalyst, (molar ratio Ni/Co=1, Ni_0.5 Co_0.5 @C), displayed excellent performance in the hydrogenative ring-rearrangement of HMF into HCPN (>90 % yield). The high selectivity of the catalyst was attributed to the formation of NiCo alloy structures as hydrogenating sites that limited competitive reactions such as the hydrogenation of furan ring and the over-reduction of the formed HPCN. The subsequent reductive amination of HPCN with aqueous ammonia was performed giving the target cyclopentylaminoalcohol in 97 % yield. Moreover, the catalyst exhibited high stability maintaining its activity and selectivity for repeated reaction cycles.

Recent Advances in Reductive Upgrading of 5-Hydroxymethylfurfural via Heterogeneous Thermocatalysis

The catalytic conversion of 5-hydroxymethylfufural (HMF), one of the vital platform chemicals in biomass upgrading, holds great promise for producing highly valuable chemicals through sustainable routes, thereby alleviating the dependence on fossil feedstocks and reducing CO₂ emissions. The reductive upgrading (hydrogenation, hydrogenolysis, ring-opening, ring-rearrangement, amination, etc.) of HMF has exhibited great potential to produce monomers, liquid fuel additives, and other valuable chemicals. Thermocatalytic conversion has a significant advantage over photocatalysis and electrocatalysis in productivity. In this Review, the recent achievements of thermo-reductive transformation of HMF to various chemicals using heterogeneous catalytic systems are presented, including the catalytic systems (catalyst and solvent), reaction conditions, (reaction temperature, pressure, etc.), and reaction mechanisms. The current challenges and future opportunities are discussed as well, aiming at guiding the catalyst design and practical scalable productions.

Molybdenum carbide anchored on glucose-derived carbon (β-Mo2C@C) as a bifunctional catalyst for conversion of fructose to 2,5-diformylfuran

Molybdenum carbide anchored on glucose-derived carbon (β-Mo2C@C) has been successfully synthesized and applied as a bifunctional catalyst for one-pot conversion of fructose to DFF.

Dehydration of fructose to 5-hydroxymethylfurfural over a mesoporous sulfonated high-crosslinked polymer in different solvents

SHCP was active and stable for dehydration of fructose to 5-HMF in DIO/H2O as H2O depressed oligomerization of 5-HMF.

High-efficiency synthesis of 5-hydroxymethylfurfural and 2,5-diformylfuran from fructose over magnetic separable catalysts

In this work, a sulfonic acid-functionalized magnetic separable solid acid (Fe₃O₄@SiO₂-SO₃H) was synthesized, characterized, and tested for fructose conversion to 5-hydroxymethylfurfural (HMF). Results indicated that the prepared catalyst had a good efficacy for fructose dehydration to HMF due to its larger specific surface area, appropriate acid amount and homogeneous acid distribution. The maximum HMF yield of this work was 96.1 mol%. It was obtained at 120 °C for 1.5 h with 100 mol% fructose conversion. More importantly, the produced HMF could be further in-situ oxidized into 2,5-diformylfuran (DFF) after the replacing of the Fe₃O₄@SiO₂-SO₃H with a ZnFeRuO₄ catalyst, and the highest DFF yield of 90.2 mol% (based on initial fructose) was obtained after reaction another 8.5 h. The production of DFF from fructose through the above two consecutive steps avoids the intermediate HMF separation, which saves time and energy. In addition, both Fe₃O₄@SiO₂-SO₃H and ZnFeRuO₄ catalysts exhibited satisfied stability in the recycling experiments, which can be reused at least for five times with the HMF and DFF yield loss<5.3% and 3.3%, respectively. Finally, the plausible reaction mechanisms for fructose conversion to HMF or DFF over Fe₃O₄@SiO₂-SO₃H or/and ZnFeRuO₄ catalysts were also proposed in this work.

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.

Synthesis and characterization of an α-MoO3 nanobelt catalyst and its application in one-step conversion of fructose to 2,5-diformylfuran

α-MoO3 nanobelts have been successfully synthesized and applied as a bifunctional catalyst for one-step conversion of fructose to DFF under atmospheric air.

Critical practices in conducting electrochemical conversion of 5-hydroxymethylfurfural

This work systematically studied the effects of various experimental parameters on the catalytic activity and product yield of HMF conversion and affords a rigorous assessment protocol for conducting electrochemical conversion of HMF.

Highly efficient and tunable visible-light-catalytic synthesis of 2,5-diformylfuran using HBr and molecular oxygen

This paper discloses that inexpensive hydrobromic acid (HBr) is active and highly selective to the photo-oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) with dioxygen (O₂) or even with water under visible light illumination, which can achieve the highest 89.1% DFF yield in DMSO at 80 °C under pure O₂ atmosphere. More importantly, under bifunctional acid-photooxidation catalysis of HBr, fructose can be directly converted to DFF and its two-step cascade conversion in DMSO provides a far higher DFF yield (80.2%) than the one-step cascade conversion in MeCN (42.1%). The results of HMF photooxidation catalyzed by hydrohalic acids, free radical quenching tests and EPR spectrum support that the Br atom and superoxide (O₂⁻˙) anion radicals generated by HBr photolysis in O₂ are active species for the oxidation of HMF to DFF and their activities are adjusted by the reaction medium. This photo-synthetic protocol is very simple and practical, especially with low operating costs, showing a good industrial application prospect.

HBr is a very cheap and efficient bifunctional catalyst for the synthesis of DFF from the photooxidation of HMF by O₂ and from the cascade conversion of fructose via a one-step or especially the two-step protocol.

Insights into the catalytic mechanism of 5-hydroxymethfurfural to phthalic anhydride with MoO3/Cu(NO3)2 in one-pot

A synthetic approach to obtain renewable phthalic anhydride (PA) from 5-hydroxymethfurfural (HMF) with a yield of 63.2% using MoO₃/Cu(NO₃)₂ as a catalyst in one pot.

One-step synthesis of 2,5-diformylfuran from monosaccharides by using lanthanum(III) triflate, sulfur, and DMSO

The combination of lanthanum(iii) triflate, sulfur, and dimethyl sulfoxide prompted a facile, direct preparation of 2,5-diformylfuran from glucose and fructose. The one-step dehydration/oxidation of fructose afforded 2,5-diformylfuran in an excellent yield with high selectivity. The proposed mechanism, large-scale synthesis, and product separation were presented. This approach represents a straightforward and eco-friendly pathway, which can be applied in the large-scale production of 2,5-diformylfuran from fructose.