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In this work, a uniquely designed imidazolium-based dicationic ionic liquid (IL) was synthesized as a greener template and applied for the synthesis of ZSM-5 zeolite as a heterogeneous catalyst for the dehydration of fructose to 5-hydroxymethylfurfural (HMF). Characterization results confirmed that due to the presence of dicationic IL as template, effective interactions and structural alterations occurred during the construction of zeolitic framework wherein the vertices of ZSM-5 consisting of Al or Si and O elements were assumed to be bonded between the vertices of dicationic IL-assisted zeolite ZSM-5 catalyst. This resulted in superior structural advantages such as highly crystalline nature and stability as well as variation in mesopores when compared to commercial ZSM-5. Additionally, various reaction variables were investigated wherein synthesized dicationic IL-assisted ZSM-5 zeolite catalyst in the presence of [BMIm][Cl] as solvent demonstrated 95% conversion of fructose and 67.2% yield of HMF at 110°C within 90 min. The altered surface area and porous nature of synthesized ZSM-5 due to the presence of dicationic IL as template was responsible for the enhanced catalytic performance under mild reaction conditions. Most significantly, being a solid catalyst, the newly developed dicationic IL-assisted zeolite ZSM-5 catalyst showed recyclability for four recycles. [ABSTRACT FROM AUTHOR]

Calcium fluoride (CaF 2) quantum dots have many applications in various fields. But there is no report on fluorescent characteristics of CaF 2 quantum dots (CaF 2 QDs). Here, a synthesis of multiple-color emission CaF 2 QDs by changing the temperature, time and raw ratio is reported, by which the CaF 2 QDs with purple, blue, green, and yellow emission can be obtained, respectively. They were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). On this basis, a novel molecular imprinting ratiometric fluorescence sensor (MIR sensor) had been constructed based on the prepared CaF 2 QDs and CdTe QDs, in which the yellow emission CaF 2 QDs was used as a responsive signal material and the red emission CdTe QDs was served as a reference signal material. And the β-CD and methylacrylic acid (MAA) as bifunctional monomers were used for constructing the specific molecularly imprinted polymers (MIPs) in MIR sensor. This MIR sensor was applied for highly selective and excellent sensitive detection of 5-hydroxymethylfurfural (HMF). Under optimum conditions, it exhibited an excellent linear relationship between the fluorescence intensity ratio (I 599 /I 625) and the concentration of HMF in the range of 0.1–6.0 μg/mL with a detection limit of 0.043 μg/mL. Finally, the established HMF-MIR sensor was successfully utilized to detect HMF in honey with satisfactory results. This work provided a reference for the application of the CaF 2 QDs and the detection of the furfural substances. Image 1 • The multiple color emission CaF 2 QDs had been synthesized for the first time. • A novel MIR sensor based on CaF 2 QDs was used for the visual detection of HMF in honey. • A specific HMF-MIR sensor had been constructed by using β-CD and MAA as functional monomers. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ir supported on SiO 2 was investigated for 5-hydroxymethylfurfural (HMF) conversion. • Hydrogenation route from HMF to 2,5- bis -(hydroxymethyl)furan (BHMF) was preferred. • Ir dispersion combined with acid sites and H 2 SO 4 promoted 2,5-dimethylfuran formation. • High activity to value-added products was achieved over Ir supported on SiO 2. Abstract Catalytic performance of iridium supported on SiO 2 was investigated for 5-hydroxymethylfurfural (HMF) transformation. Ir/SiO 2 catalysts exhibiting different metal loading (1, 3, and 5 wt.%) were tested in the preliminary experiments in the hydrogenation of two probe molecules, e.g. ethyl pyruvate (EP) and ketopantolactone (KP) to evaluate the Ir dispersion on the catalyst activity in C O hydrogenation. In the transformation of HMF the influence of metal dispersion, iridium precursor and addition of H 2 SO 4 were studied revealing that 2,5- bis -(hydroxymethyl)furan (BHMF) was the main product with 83% selectivity at 70% conversion of HMF over chlorine free Ir/SiO 2 together with H 2 SO 4 at 333 K in THF under 10 bar H 2 pressure. On the other hand, one-pot synthesis of HMF to 2,5-dimethylfuran (DMF) was promoted in the presence of chlorine containing 1%Ir/SiO 2 (Cl) and H 2 SO 4. Both of these products are considered high value-added chemicals from biomass-derived 5-hydroxymethylfurfural. The exposed iridium atoms together with the total acid sites are an important catalytic descriptor for hydrogenation of HMF to BHMF. [ABSTRACT FROM AUTHOR]

2,5-Furandicarboxylic acid (FDCA) and 5-hydroxymethylfurfural (HMF) are top biomass-based platform chemicals with promising potential and an essential part of the future of green chemistry. HMF can be obtained mainly from fructose or glucose. Lignocellulosic glucose has a high production potential from not edible biomass. In the present paper life cycle assessment (LCA) was performed aiming at a better understanding of the environmental performance of the production of FDCA and HMF from lignocellulosic feedstock. Two case studies from the literature were modeled to obtain the life cycle inventory data. The production routes to FDCA comprise seven different process sections: hydrolysis, HMF synthesis, HMF recovery, FDCA synthesis, FDCA flash separation, FDCA purification and HMF boiler. By means of the LCA methodology, solvents such as dimethyl sulfoxide (DMSO) and dichloromethane (DCM), together with the energy demand, were found to be clear critical points in the process. Two scenarios were in focus: Scenario 1 considered the purification of FDCA through crystallization, whereas in Scenario 2 purification was performed through distillation. [ABSTRACT FROM AUTHOR]

The first principle calculations with on-site Coulomb repulsion U terms were carried out to investigate the 5-hydroxymethylfurfural (HMF) adsorption on the CuO(1 1 1) and Co 3 O 4 (1 1 0) surfaces, two widely used oxidation catalysts. The adsorption of HMF molecule is energetically favoured in both cases, and HMF is more inclined to bridge adsorption via hydroxyl and formyl groups binding with surface O and metal sites. Moreover, the adsorption energy relies on both the coordination type of surface lattice oxygen to which the H atom binds and the formation of H-bond involving hydroxyl and formyl groups on the adsorbed HMF. Also, the hydroxyl O H bond breaking is very easy and is likely to be the first step in HMF oxidation, and then the OH insertion reaction to produce 2,5-furandicarboxylic acid (FDCA). The corresponding experimental results also show that the CuO and Co 3 O 4 surfaces are promising candidate catalysts. [ABSTRACT FROM AUTHOR]

Abstract In this survey, ultrasonic irradiation was used as a source of energy and a mild method for producing 5-hydroxymethylfurfural (5-HMF) from fructose in the presence of SBA-15 grafted with different amount of alumina at room temperature. Effect of different parameters such as the power of ultrasonic irradiation, alumina loading on SBA-15, catalyst amount, reaction time, and solvent was investigated. Catalysts were characterized using different techniques such as FT-IR, XRD, BET, SEM, TEM, EDX, elemental mapping and ICP analysis. While dehydration reaction at room temperature gave <5% 5-HMF after 48 h, after 150 min sonication under the power of 300 W the HMF yield reached to 47% at room temperature. The effect of various solvents such as DMSO, NMP, DMF and sulfolane was investigated and DMSO was selected as suitable solvent for dehydration of fructose. Finally, the reusability of catalyst was examined and it was found that the recovered catalyst showed high activity in repeated experiments. [ABSTRACT FROM AUTHOR]

One-pot synthesis of 5-hydroxymethylfurfural (HMF) from cellulose or glucose through employing a concentrated solution of LiBr as solvent together with a combined metal (II) and surfactant catalyst was studied. First, cellulose was dissolved in the solvent, and then it was hydrolyzed with hydrogen bromide (HBr) under moderate conditions before the solution was neutralized. The next step toward HMF synthesis was performed at 140 °C for 3 h with the addition of the abovementioned catalyst at a 10 mol% level of the substrate. Metal (II) chlorides that could serve as a Lewis acid (i.e., catalysts), or combined metal (II) and surfactant catalysts, were adopted for converting glucose to HMF. The yield of HMF reached 30.5% from glucose, and 33.8% from cellulose when tin (II) dodecylsulfate was used as a Lewis acid catalyst. The catalyst containing tin (II) yielded better results than those that contained zinc (II) or copper (II). [ABSTRACT FROM AUTHOR]

This study investigated acrylamide and 5-hydroxymethylfurfural (HMF) formation during biscuit baking. Four types of wheat flour with different molar ratios of total fructose and glucose to asparagine were investigated. Nevertheless, the molar ratio in all four biscuit doughs exceeded one after proofing due to enzyme action. Data obtained after baking were used to develop a mechanistic model, based on the asparagine-related pathway, for acrylamide and HMF formation in the four baked biscuit types. Asparagine reacted with fructose to form a Schiff base before decarboxylation to produce acrylamide without Amadori rearrangement product and sugar fragmentation. Fructose contributed considerably to acrylamide formation and to HMF formation via caramelization in all four biscuit types. No clear correlation was found between acrylamide and HMF in baked biscuits, nor between asparagine and the sum of glucose and fructose concentrations in the wheat flour. [ABSTRACT FROM AUTHOR]

In this study, a new method was developed for the oxidation of 5-hydroxymethylfurfural (HMF) into 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) over heterogeneous Ru catalyst. Cs-substituted tungstophosphate (CsPW) was prepared by the exchange of H + in H 3 PW 12 O 40 with Cs + , which was then used to immobilize Ru nanoparticles to give the Ru/CsPW catalyst. The Ru/CsPW catalyst was well characterized by TEM, XRD, XPS and FT-IR technologies. The physical characterizations clearly indicated that the spherica Ru nanoparticles with an average size of 2.4 nm were homogeneously dispersed on the surface of the CsPW support. The as-prepared catalyst was studied for the oxidation of HMF, and some important parameters were investigated. The reaction solvent showed a great effect on both HMF conversion and the products selectivity. Aromatic solvents were found to be the best reaction medium for the oxidation of HMF into HMFCA. Increasing the reaction temperature and the amount of the Ru/CsPW catalyst accelerated the HMF conversion and HMFCA yield. High HMF conversion of 97.2% and HMFCA yield of 72.9% were obtained after 12 h at 130 °C with oxygen flow rate of 20 ml/min. Unfortunately, the Ru/CsPW catalyst was not very stable during the reaction, and a slight loss of its catalytic activity was observed during the recycling experiments. [ABSTRACT FROM AUTHOR]

An efficient production of 5-hydroxymethylfurfural (HMF) from raw lignocellulosic biomass is achieved through combinational treatments of diluted acid/base-assisted pretreatment and catalytic conversion. Remarkably, an HMF yield of around 79 mol% could be achieved when the raw lignocellulosic biomass (wood chips) was pre-treated in diluted NaOH solution (3 wt%) and then catalyzed in the system using CrCl 3 ·6H 2 O as the catalyst and 1-butyl-3-methyl imidazolium chloride ([BMIM]Cl) as the solvent at 120 °C for 2 h. In addition, the activation energy for producing HMF was calcuted to be around 74 kJ/mol in our system. The combinational treatments proposed in this study demonstrate an effective transformation of raw lignocellulosic biomass into HMF with a high yield. [ABSTRACT FROM AUTHOR]

The process of dehydration of glucose to 5-hydroxymethylfurfural (HMF), using caprolactam-lithium chloride (CPL/LiCl) as a solvent, was investigated. Dual-wavelength ultraviolet spectrophotometry provides a new approach for the determination of glucose conversion rate and yield of HMF. Experiments were performed to demonstrate the accuracy and precision of this method. Various reaction parameters, such as the ratio of ionic liquid, reaction temperature, reaction time, catalyst dosage, and solid absorbent, were investigated in detail for the dehydration of glucose. The optimal conditions were explored. Finally, a possible mechanism for the dehydration of fructose to HMF was proposed. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of sugar type on the reaction mechanism for formation of acrylamide and 5-hydroxymethylfurfural (HMF) during the baking of biscuits at 200 °C using multiresponse modelling. Four types of biscuits were prepared: (1) with sucrose, (2) with glucose and fructose, (3) with fructose only and (4) with glucose only. Experimental data showed that HMF concentration was highest in biscuits with glucose and fructose, whereas acrylamide concentration was highest in biscuits with glucose, also having the highest asparagine concentration. Proposed mechanistic models suggested that HMF is formed via caramelisation and that acrylamide formation follows the specific amino acid route, i.e., reducing sugars react with asparagine to form the Schiff base before decarboxylation, to generate acrylamide without the Amadori rearrangement product and sugar fragmentation. Study results contribute to understanding chemical reaction pathways in real food products. [ABSTRACT FROM AUTHOR]

Background: Current large-scale pretreatment processes for lignocellulosic biomass are generally accompanied by the formation of toxic degradation products, such as 5-hydroxymethylfurfural (HMF), which inhibit cellulolytic enzymes and fermentation by ethanol-producing yeast. Overcoming these toxic effects is a key technical barrier in the biochemical conversion of plant biomass to biofuels. Pleurotus ostreatus, a white-rot fungus, can efficiently degrade lignocellulose. In this study, we analyzed the ability of P. ostreatus to tolerate and metabolize HMF and investigated relevant molecular pathways associated with these processes. Results: P. ostreatus was capable to metabolize and detoxify HMF 30 mM within 48 h, converting it into 2,5-bis-hydroxymethylfuran (HMF alcohol) and 2,5-furandicarboxylic acid (FDCA), which subsequently allowed the normal yeast growth in amended media. We show that two enzymes groups, which belong to the ligninolytic system, aryl-alcohol oxidases and a dehydrogenase, are involved in this process. HMF induced the transcription and production of these enzymes and was accompanied by an increase in activity levels. We also demonstrate that following the induction of these enzymes, HMF could be metabolized in vitro. Conclusions: Aryl-alcohol oxidase and dehydrogenase gene family members are part of the transcriptional and subsequent translational response to HMF exposure in P. ostreatus and are involved in HMF transformation. Based on our data, we propose that these enzymatic capacities of P. ostreatus either be integrated in biomass pretreatment or the genes encoding these enzymesmay function to detoxify HMF via heterologous expression in fermentation organisms, such as Saccharomyces cerevisiae. [ABSTRACT FROM AUTHOR]

Three zeolitic imidazolate frameworks (ZIF-8, ZIF-90 and ZIF-93) were investigated for adsorption of 5-hydroxymethylfurfural (HMF) from aqueous solution. The equilibrium uptake of HMF decreased following the order of ZIF-8 (465 mg g −1 )>ZIF-90 (307 mg g −1 )>ZIF-93 (279 mg g −1 ), in accordance with the hydrophobicity of the frameworks. The adsorption equilibrium data were found to follow Langmuir adsorption model. The sorption kinetics could be well described by the pseudo-second-order kinetic equation. The HMF-loaded ZIFs could be fully regenerated with ethanol as the desorption solvent. Selective adsorption of HMF from HMF/fructose/water mixtures was also carried out. The uptake of HMF remained unchanged, with no observable adsorption of fructose. In liquid phase breakthrough experiments, the uptake of HMF on ZIF-8 in column was consistent with the batch study. Furthermore, the ZIF-8 packed column could be regenerated effectively and recycled with no discernible loss of adsorption capacity. These findings confirm that ZIF-8 can be employed as an effective and reusable adsorbent for HMF recovery from aqueous solution. [ABSTRACT FROM AUTHOR]

5-hydroxymethylfurfural (HMF) is an important marker of food processing and storage widely recognized as an important parameter of food freshness and quality. Its amount depends on the composition of a food product and on the thermal treatments to which the food is subjected. The aim of this work was to propose for the first time the optimization and validation of an innovative CE-MS2 method for the quantification of HMF in food products exploiting selected product ion monitoring as acquisition mode. The method was applied to the analysis of different kind of samples: cereal-based baby foods, coffee, soft beverages and vinegars. In order to show the reliability of the proposed method, results were compared with those obtained by RP-HPLC-UV, and a good accordance between the two sets of data was found. [ABSTRACT FROM AUTHOR]

Highlights: [•] The extraction process for 5-hydroxymethylfurfural (HMF) was optimised. [•] RP-HPLC method was developed for the detection of HMF in crude palm oil. [•] The method was validated and showed good precision and accuracy. [•] The presence of 5-hydroxymethylfurfural in crude palm oil was confirmed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Unsymmetrical dicationic imidazolium based ILs were synthesized. [•] Imidazolium, pyridinium, and triethyl ammonium cations were used. [•] Prepared ILs showed efficient catalytic activity in fructose dehydration. [•] 100% fructose conversion and 92.3% HMF yield was obtained. [•] 70°C temperature and 40min reaction time gave the good results. [ABSTRACT FROM AUTHOR]

Highlights: [•] The effect of thermal processing on the formation of HMF in honey was studied. [•] Microwave field, greatly accelerates the formation of HMF in honey. [•] Heat treatment did not significantly affect the antioxidant properties of honey. [ABSTRACT FROM AUTHOR]

Abstract: Maize grains were heated by infrared radiation for 50–100 s, than flaked and milled. The output was set to 110, 115, 120 and 140 °C to determine the effect of temperature on the formation of acrylamide, 5-hydroxymethylfurfural (HMF) and furosine, as well as the level of phenolic compounds in maize flour and its total antioxidant capacity (TAC). Acrylamide and HMF levels were increased as the load of the heat treatment was increased in grains, while furosine concentration was rapidly increased to an apparent maximum (34.96 μg/g) followed by decrease during heating. Acrylamide, as well as HMF variables correlated very well with TAC of heat-treated flour (r 2 = 0.98 and 0.86). The process of infrared heating had a great influence on the reduction of phenolic compound contents. However, new antioxidants that were formed as a result of the Maillard reaction increased the total antioxidant capacity of heat-treated maize flour. [Copyright &y& Elsevier]

A novel production of biobased p-xylene from hydroxymethylfurfual has been investigated and presented. This is an important part of a process for the production of aromatics from lignocellulosic biomass. The detailed flow sheets are designed based on laboratory experiments by Leshkov et al. and William et al. and economic analysis has been performed. The minimum biobased p-xylene cost is estimated as $3,962/metric ton, of which the main contribution comes from the HMF cost. Sensitivity analysis has been used to assess the impact of uncertainties of economic parameters and also to determine the most significant reaction factor in the technological development, i.e., selectivity and conversion. It has been shown that high selectivity is favored at the same yield. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2079-2087, 2013 [ABSTRACT FROM AUTHOR]

Abstract: Acidity modified silver exchanged silicotungstic acid (AgSTA) catalyst was prepared and characterized by X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, FT-IR pyridine adsorption, SEM imaging, EDX mapping, and antimicrobial activity was also tested. The catalytic activity was evaluated for the dehydration of fructose and sucrose in superheated water. As a result, 98% conversion of fructose with 85.7% HMF yield and 87.4% HMF selectivity in 120min reaction time at 120°C reaction temperature using 10wt.% of AgSTA catalyst was achieved. While, 92% sucrose conversion with 62.5% of HMF yield was obtained from sucrose at uniform condition in 160min. The effect of reaction parameters, such as reaction temperature, time, catalyst dosage, and effect acidity on HMF yield was also investigated. The AgSTA catalyst was separated from the reaction mixture by filtration process at end of the reaction and reused eight times without loss of catalytic activity. [Copyright &y& Elsevier]

The formation of hydroxymethylfurfural, nonenzymatic brown coloured compounds and free sulphydryl groups in goat milk was studied during heating at 75-95 °C. Analysis of kinetic data suggested that formation of hydroxymethylfurfural and nonenzymatic brown coloured compounds followed zero order reaction kinetics, while formation of free sulphydryl groups during heating varied depending on heating time. A good linear correlation ( r = 0.839) was found between brown coloured compounds and hydroxymethylfurfural content in milk samples during heating. Activation energies ( Ea) for the formation of hydroxymethylfurfural and nonenzymatic brown coloured compounds were 96.31 and 69.79 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Mesoporous SBA-15 materials functionalized with propylsulfonic acid groups (SBA-15-SO3H) were synthesized through a conventional one-pot route. It was used as a catalyst for the selective synthesis of 5-hydroxymethylfurfural (HMF) from the dehydration of fructose using BmimCl as solvent. Reaction time, temperature and fructose concentration were investigated during the HMF synthesis procedure. The catalyst SBA-15-SO3H exhibits high fructose conversion (near 100%) and HMF selectivity (about 81%) with good stability in the HMF synthesis. It was a suitable catalyst to produce HMF from renewable carbohydrates in potential industrial process. [Copyright &y& Elsevier]

[Display omitted] • 3D porous WO 3 /Ni electrodes were controllably synthesized at low temperature. • The 3D porous WO 3 /Ni electrode was efficient for oxidation of HMF into FDCA. • The nanorod-like WO 3 and large ECSA enhanced electrochemical oxidation of HMF. • W6+ species in WO 3 participated in the oxidation of HMF by reduction to W5+. 2,5-furandicarboxylic acid (FDCA) is a key precursor for the sustainable synthesis of environmentally friendly materials such as polyethylene 2,5-furandicarboxylate (PEF). Developing noble-metal free and robust electrocatalysts are of great importance for the eco-friendly upgrading of biomass-derived 5-hydroxymethylfurfural (HMF) to produce FDCA. Herein we demonstrated a facile one-step hydrothermal method to grow tungsten trioxide (WO 3) nanorods on Ni foam, which was efficient for the electrochemical oxidation of HMF to FDCA. The 3D porous WO 3 /Ni electrode was controllably synthesized at low temperature with the aid of polyethylene glycol (PEG) template. Three types of electrodes were investigated and the catalytic results showed excellent electrochemical performance with the high electrochemically active surface area (ECSA) up to 40.0 cm2, 99.4 % HMF conversion rate, 88.3 % FDCA yield and 88.0 % Faradaic efficiency in 1.0 M KOH electrolyte under ambient conditions, avoiding the traditionally harsh environment (e.g. extra oxygen sources, high temperature and pressure). Besides, the product distribution, reaction kinetics and mechanisms were also investigated. This work provides an alternative and efficient way of electrocatalytic processing of biomass-derived monomers using noble-metal free catalysts under ambient conditions. [ABSTRACT FROM AUTHOR]

• The composition of wood dust and its byproducts from SE process were identified. • The constituents of DESs affect the yield and selectivity of HMF was determined. • The reaction conditions affect the yield and selectivity of HMF was explored. • Optimal conditions for using pretreated wood dust to produce HMF were identified. 5-hydroxymethylfurfural (HMF) is a versatile biomass-derived chemical for synthesizing useful compounds. In this work an attempt is made to produce HMF by developing a low-cost process for doing that using cellulosic waste and deep eutectic solvents (DESs). The most effective DES was choline chloride/citric acid (ChCl/citric acid, 2/1), which provided a greater glucose conversion percentage (around 100 mol%), HMF yield (8 mol%), and HMF selectivity (8 %) than other DESs with 0.1 g of pure glucose. To increase the HMF yield further, the species of catalyst, reaction time and reaction temperature were varied. The highest glucose conversion percentage (91.76 mol%), HMF yield (15.02 g/g) and HMF selectivity (8%) were obtained with a reaction time of five minutes, a reaction temperature of 130 ℃, sulfuric acid as the catalyst, and a ChCl/citric acid ratio of the DES of 2/1. These optimal conditions were used with the enzymatic hydrolysate of pretreated wood dusts as a substrate. The experimental results thus obtained revealed a glucose conversion percentage, HMF yield and HMF selectivity of 34.86 mol%, 16.46 g/g and 67.43 %, respectively, under these conditions. These results reveal that using enzymatic hydrolysate from pretreated wood in the production of HMF can yield approximately as much (16.46 g/g) as the use of pure glucose, indicating that this low-cost process may be commercially feasible. [ABSTRACT FROM AUTHOR]