Glucose-based Carbohydrates Research Articles

Mechanisms contributing to lactose and sucrose-induced postprandial lipaemia

Fructose-containing sugars can exaggerate postprandial lipaemia and stimulate hepatic de novo lipogenesis (DNL) when compared to glucose-based carbohydrates(1). Galactose has recently been shown to increase postprandial lipaemia compared to glucose(2), but mechanisms remain uncharacterised. The aim of this study was to assess the effect and mechanisms of lactose-induced lipaemia.Twenty-four non-obese adults (12 male and 12 female) completed three trials in a randomised, crossover design (28 ± 7-day washout). During trials, participants consumed test drinks containing 50 g fat with 100 g of carbohydrate. The control carbohydrate was a glucose polymer (maltodextrin), the experimental carbohydrate was galactose-containing carbohydrate (lactose) and the active comparator was fructose-containing carbohydrate (sucrose). Hepatic DNL was assessed by the 2H2O method and [U-13C]-palmitate was added to the test drink to trace the fate of the ingested fat. Blood and breath samples were taken to determine plasma metabolite and hormone concentrations, in addition to plasma and breath 2H and 13C enrichments. Data were converted into incremental under the curve (iAUC) and were checked for normality by visual inspection of residuals. Differences between trials were assessed by one-way ANOVA. Where a main effect of trial was detected, post- hoc t-tests were performed to determine which trials differed from lactose according to the principle of closed-loop testing.The plasma triacylglycerol iAUC (mean ± SD) in response to maltodextrin was 51 ± 68 mmol/L*360 min. Following lactose ingestion, plasma triacylglycerol iAUC increased to 98 ± 88 mmol/L*360 min (p<0.001 vs maltodextrin), which was comparable to sucrose [90 ± 95 mmol/L*360 min (p=0.41 vs lactose)]. Hepatic DNL in response to maltodextrin was 6.6 ± 3.0%. Following ingestion of lactose, hepatic DNL increased to 12.4 ± 6.9% (p=0.02 vs maltodextrin), which was comparable to sucrose [12.2 ± 6.9% (p=0.96 vs lactose)]. Exhaled 13CO2 in response to maltodextrin was 10.4 ± 4.1 mmol/kgFFM*360 min. Following ingestion of lactose, exhaled 13CO2 was 8.8 ± 4.9 mmol/kgFFM*360 min (p=0.09 vs maltodextrin), which was lower than sucrose [11.1 ± 3.9 mmol/kgFFM*360 min (p=0.01 vs lactose)].These data are consistent with the hypothesis that hepatic de novo lipogenesis contributes to both lactose and sucrose-induced lipaemia and provide a rationale to investigate the longer-term effects of lactose and sucrose on metabolism.

Discovery of natural agents against Staphylococcus aureus based on EIIC by protein modeling, virtual screening and molecular dynamics

In this study, a reasonable 3D structure of enzyme IIC (EIIC) was established using ab initio methods. Curcumin, baicalein and phloretin were screened out from 127,695 natural products based on EIIC protein in Staphylococcus aureus (S. aureus) by using the virtual screening technology. The antibacterial assays results confirmed that these three compounds could inhibit S. aureus cell growth. The results of molecular docking, molecular dynamics and molecular mechanics/generalized born surface area calculation indicated that curcumin, baicalein and phloretin mainly bound to Glu275, His231, and Phe359 of EIIC through hydrogen bonds and van der Waals forces to obstruct the transport of glucose-based carbohydrates, and thereby inhibited the carbohydrate metabolism of S. aureus. The steered molecular dynamics analysis revealed the existence of transfer channel in EIIC and illustrated that curcumin, baicalein and phloretin could dissociate from EIIC when pulling force on them. Furthermore, alanine scanning and hydrogen bond occupancy analyses found that Glu275 played an important role in stabilizing EIIC-baicalein/curcumin/phloretin complexes, and 275Glu@OE1 was a stable hydrogen bond acceptor. Therefore, Glu275 may be a hot spot residue that can maintain the stable binding of agents to EIIC, which may be a direction for the development of new drugs against S. aureus.

Long-Term Hindrance Effects of Algal Biomatter on the Hydration Reactions of Ordinary Portland Cement

The incorporation of carbon-fixing materials such as photosynthetic algae in concrete formulations offers a promising strategy toward mitigating the concerningly high carbon footprint of cement. Prior literature suggests that the introduction of up to 0.5 wt % chlorella biological matter (biomatter) in ordinary Portland cement induces a retardation of the composite cement’s strength evolution while enabling a long-term compressive strength comparable to pure cement at a lower carbon footprint. In this work, we provide insights into the fundamental mechanisms governing this retardation effect and reveal a concentration threshold above which the presence of biomatter completely hinders the hydration reactions. We incorporate Chlorella or Spirulina, two algal species with different morphology and composition, in ordinary Portland cement at concentrations ranging between 0.5 and 15 wt % and study the evolution of mechanical properties of the resulting biocomposites over a period of 91 days. The compressive strength in both sets of biocomposites exhibits a concentration-dependent long-term drastic reduction, which plateaus at 5 wt % biomatter content. At and above 5 wt %, all biocomposites show a strength reduction of more than 80% after 91 days of curing compared to pure cement, indicating a permanent hindrance effect on hardening. Characterization of the hydration kinetics and the cured materials shows that both algal biomatters hinder the hydration reactions of calcium silicates, preventing the formation of calcium hydroxide and calcium silicate hydrate, while the secondary reactions of tricalcium aluminate that form ettringite are not affected. We propose that the alkaline conditions during cement hydration lead to the formation of charged glucose-based carbohydrates, which subsequently create a hydrogen bonding network that ultimately encapsulates calcium silicates. This encapsulation prevents the formation of primary hydrate products and thus blocks the hardening of cement. Furthermore, we observe new hydration products with composition and micromorphology deviating from the expected hardened cement compounds. Our analysis provides fundamental insights into the mechanisms that govern the introduction of two carbon-negative algal species as fillers in cement, which are crucial for enabling strategies to overcome the detrimental effects that those fillers have on the mechanical properties of cement.

Top-Down Production of Sustainable and Scalable Hemicellulose Nanocrystals.

Polysaccharide nanocrystals have led to the development of multifunctional and sustainable materials, but most are glucose-based carbohydrates derived from valuable natural sources. Here, we present a top-down strategy that enables one, for the first time, to isolate xylose-based hemicellulose nanocrystals from available industrial biowastes. By leveraging the selective oxidation of alkaline periodate, as high as 34 wt % solid yield is accessible. The hemicellulose nanocrystals exhibit platelet-like shapes (10-20 nm thickness, 30-80 nm wide), crystalline features, and superior dispersibility in water. We also showcase their successful interface applications for one-dimensional (1D) carbon nanotube (CNT) nanoinks and two-dimensional (2D) transition-metal dichalcogenide (TMD) nanozymes, which are comparable to the traditional cellulose nanocrystals. The scalable, low-cost, and sustainable hemicellulose nanocrystals can be envisioned to provide an alternative for glucose-based polysaccharide nanocrystals, as well as hold promise for the high-value utilization of biowastes.

Efficient 5-hydroxymethylfurfural synthesis from carbohydrates and food wastes in aqueous-natural deep eutectic solvent (A-NADES) with robust Al2O3 or Al(OH)3

As one of the essential building blocks for bio-chemicals and bio-fuels, the 5-Hydroxymethylfurfural (HMF) production is still challenging in a green and cheap way. This work developed a bio-derived aqueous-natural deep eutectic solvent (A-NADES) to synthesize HMF using α-Al2O3 or Al(OH)3 as robust catalysts, obtaining high yields of 67.1% and 63.6% HMF from glucose under mild reaction reactions, respectively. Different kinds of starches and starchy food waste also exhibited high conversion efficiency in the A-NADES system. The mechanistic study indicated that the in-situ formed Al (III) site of α-Al2O3 during the reaction was critical for converting glucose-based carbohydrates. A-NADES could be effectively reused six times with a more convenient direct reuse method without significant activity loss. This study suggested a novel A-NADES reaction media in the synergistic reaction with robust aluminum-based catalysts for HMF synthesis, and proposed a novel process of food waste utilization in green solvents.

Carb-conscious: the role of carbohydrate intake in recovery from exercise.

The present review summarized evidence on the role of carbohydrates in recovery from exercise within the context of acute and chronic effects on metabolism and performance. Recent studies demonstrate that, in contrast to recovery of muscle glycogen stores, the recovery of liver glycogen stores can be accelerated by the co-ingestion of fructose with glucose-based carbohydrates. Three recent studies suggest this can extend time-to-exhaustion during endurance exercise tests. However, periodically restricting carbohydrate intakes during recovery from some training sessions to slow the recovery of liver and muscle glycogen stores may, over time, result in a modest increase in the ability to oxidize fat during exercise in a fasted state. Whether this periodized strategy translates into a performance advantage in the fed state remains to be clearly demonstrated. To maximize recovery of glycogen stores and the capacity to perform in subsequent endurance exercise, athletes should consider ingesting at least 1.2 g carbohydrate per kilogram body mass per hour - for the first few hours of recovery - as a mixture of fructose and glucose-based carbohydrates. However, if a goal is increased capacity for fat oxidation, athletes should consider restricting carbohydrate intakes during recovery from some key training sessions. http://links.lww.com/COCN/A15.

Selective production of glycolaldehyde via hydrothermal pyrolysis of glucose: Experiments and microkinetic modeling

Pyrolysis of glucose and glucose-based carbohydrates has been shown to produce a range of chemical species that can be used directly as fuels and chemicals or as feedstocks to further chemical transformations. It is known that process operating conditions such as temperature, heating rate, reactor configuration, moisture content, and pretreatment method can have a significant effect on the observed product distribution. Pyrolysis of carbohydrates in the presence of water at high concentrations can significantly alter the product spectrum and favor the production of specific products at unusually high yields. In this work, we show that pyrolysis of aqueous glucose solutions at high temperatures can result in highly selective production of glycolaldehyde, a C2 hydrocarbon with an aldehyde and hydroxyl functionality, toward direct applications in the food industry or as a chemical building block toward value-added products. A glucose pyrolysis model that was developed previously was expanded to capture the pyrolysis kinetics of glucose at hydrothermal conditions, accurately reproducing the observed product yields for a range of temperatures and feedstock compositions. Dominant reaction families were identified and interrogated to quantify the effect of hydrothermal conditions on the predicted kinetics. High yields of glycolaldehyde were achieved experimentally, with the maximum values observed at moderate temperatures and pure glucose feed. Elevated temperatures and increasing fructose concentrations negatively affected observed glycolaldehyde yields, resulting in increased production of undesired decomposition products in the C1-C3 range. The results of this study include preferred operating conditions toward maximizing the yield of glycolaldehyde as described by a predictive kinetic model that explicitly accounts for the major reactions comprising a complex network taking place and the effect of the operating conditions on their relative contributions to glucose conversion and product yields.

Pectin-Alginate Does Not Further Enhance Exogenous Carbohydrate Oxidation in Running.

Maximizing carbohydrate availability is important for many endurance events. Combining pectin and sodium alginate with ingested maltodextrin-fructose (MAL + FRU + PEC + ALG) has been suggested to enhance carbohydrate delivery via hydrogel formation, but the influence on exogenous carbohydrate oxidation remains unknown. The primary aim of this study was to assess the effects of MAL + FRU + PEC + ALG on exogenous carbohydrate oxidation during exercise compared with a maltodextrin-fructose mixture (MAL + FRU). MAL + FRU has been well established to increase exogenous carbohydrate oxidation during cycling compared with glucose-based carbohydrates (MAL + GLU). However, much evidence focuses on cycling, and direct evidence in running is lacking. Therefore, a secondary aim was to compare exogenous carbohydrate oxidation rates with MAL + FRU versus MAL + GLU during running. Nine trained runners completed two trials (MAL + FRU and MAL + FRU + PEC + ALG) in a double-blind, randomized crossover design. A subset (n = 7) also completed a MAL + GLU trial to address the secondary aim, and a water trial to establish background expired CO2 enrichment. Participants ran at 60% V˙O2peak for 120 min while ingesting either water only or carbohydrate solutions at a rate of 1.5 g carbohydrate per minute. At the end of 120 min of exercise, exogenous carbohydrate oxidation rates were 0.9 (SD 0.5) g·min with MAL + GLU ingestion. MAL + FRU ingestion increased exogenous carbohydrate oxidation rates to 1.1 (SD 0.3) g·min (P = 0.038), with no further increase with MAL + FRU + PEC + ALG ingestion (1.1 (SD 0.3) g·min; P = 1.0). No time-treatment interaction effects were observed for plasma glucose, lactate, insulin, or nonesterified fatty acids, or for ratings of perceived exertion or gastrointestinal symptoms (all, P > 0.05). To maximize exogenous carbohydrate oxidation during moderate-intensity running, athletes may benefit from consuming glucose(polymer)-fructose mixtures over glucose-based carbohydrates alone, but the addition of pectin and sodium alginate offers no further benefit.

Bacterial sugar-binding protein as a one-step affinity purification tag on dextran-containing resins

Marinobacter hydrocarbonoclasticus is an oil-eating bacterium that possesses a large adhesion protein (MhLap) with the potential to bind extracellular ligands. One of these ligand-binding modules is the ~20-kDa PA14 domain (MhPA14) that has affinity for glucose-based carbohydrates. Previous studies showed this sugar-binding domain is retained on dextran-based size-exclusion resins during chromatography, requiring the introduction of glucose or EDTA to remove the protein from the column. Given the ready availability of such size-exclusion resins in biochemistry laboratories, this study explores the use of MhPA14 as an affinity tag for recombinant protein purification. Two different fusion proteins were tested: 1) Green fluorescent protein (GFP) linked to the N-terminus of the MhPA14 tag; and 2) the ice-binding domain from the Marinomonas primoryensis ice-binding protein (MpIBD) linked to the MhPA14 C-terminus by a TEV cut site. The GFP_MhPA14 fusion visibly bound to Superdex, Sephadex, and Sephacryl resins, but did not bind to Sepharose. Using Superdex resin, dextran-affinity purification proved to be an effective one-step purification strategy for both proteins, superior to even nickel-affinity chromatography. Dextran-affinity chromatography was also the most effective method of separating the MhPA14 tag from MpIBD following TEV proteolysis, as compared to both nickel-affinity and ice-affinity methods. These results indicate that MhPA14 has potential for widespread use in recombinant protein purification.

Novel instrumentation for tracking molecular products in fast pyrolysis of carbohydrates with sub-second temporal resolution

Despite recent advances, little has been experimentally established regarding the detailed chemical processes that occur during biomass pyrolysis reactions. We developed a new technique that allows for the monitoring of each molecular product from fast pyrolysis with ∼0.2 s temporal resolution. This was achieved by directly coupling a micropyrolyzer with a time-of-flight mass spectrometer via a soft ionization. Molecular products studied were produced in thin-film pyrolysis of a series of glucose-based carbohydrates. Unprecedented details of the pyrolysis reaction process were revealed, including the timescale of molecular product formation and the existence of metastable intermediates. Small carbohydrates are completely pyrolyzed within one second and as short as one-half second for glucose pyrolysis. Individual time profiles could be extracted and examined for each molecular product. Additionally, the effect of sample dimensions on the pyrolysis of cellulose and α-cyclodextrin, as both thin films and particles, was studied. A surprising time delay of one second is observed for the thin-film pyrolysis of cellulose and α-cyclodextrin, which is attributed to the transition to the molten phase. When a large amount of cellulose or α-cyclodextrin is pyrolyzed, random fluctuations of temporal profiles are observed and explained as coming from aerosol ejections. This is well correlated with the high abundance of non-volatile products such as cellobiosan that cannot be detected in typical GC–MS or pyrolysis GC–MS analysis.

Mechanism of cellulose fast pyrolysis: The role of characteristic chain ends and dehydrated units

Understanding the fundamental reactions and mechanisms during biomass fast pyrolysis is essential for the development of efficient pyrolysis techniques. In this work, quantum chemistry calculation, kinetic analysis and fast pyrolysis experiment were combined to reveal the cellulose pyrolysis mechanism. During cellulose pyrolysis, the indigenous interior units, reducing end (RE end) and non-reducing end (NR end) initially form various characteristic chain ends and dehydrated units which then evolve into different pyrolytic products. As the rising of the degree of polymerization (DP), reactions occurring at the interior unit and NR end are more competitive than those taking place at the RE end, resulting in distinct pyrolytic product distribution for cellulose and glucose-based carbohydrates. The reactions occurring at the three indigenous units of cellulose chain all favor the formation of levoglucosan-terminated end (LG end) and/or NR end, which then generate levoglucosan (LG). The acyclic d-glucose end (AG end), which mainly derives from the RE end, is essential for the formation of 1,6-anhydro-β-d-glucofuranose (AGF), 1,4:3,6-dianhydro-α-d-glucopyranose (DGP), furfural (FF), 5-hydroxymethyl furfural (5-HMF) and hydroxyacetaldehyde (HAA). Compared with the chain ends, the dehydrated units are not feasible to be generated, and their decomposition favors the formation of HAA.

From glucose-based carbohydrates to phenol-rich bio-oils integrated with syngas production via catalytic pyrolysis over an activated carbon catalyst

A novel route to selectively produce phenol and carbon monoxide-enriched gas was proposed via the catalytic pyrolysis of glucose-based carbohydrates with an activated carbon catalyst.

Towards first-principles based kinetic modeling of biomass fast pyrolysis

Biomass conversion to chemicals and fuels through fast pyrolysis shows great potential but requires a more fundamental approach for its deployment. To this end, molecular-based kinetic modeling is starting to play a central role in the prediction of the molecular composition of bio-oil. A molecular-level representation of biomass provides the start point for the generation of detailed pyrolysis reaction networks for both the condensed and the gas phases. Significant progress has been made for cellulose, glucose-based carbohydrates, and lignin, together with the incorporation of the catalytic effects of minerals. Ab initio techniques are widely used to discriminate between reaction mechanisms and to calculate kinetic parameters. Automatic kinetic model generation is expected to play an even more important role in fast pyrolysis as it does already today. Experimental techniques enabled to obtain intrinsic kinetics and to decouple the timescales between reaction kinetics and analytic techniques. This greatly benefits the improvement of detailed kinetic models. The prospects for achieving a first-principles based kinetic model of biomass fast pyrolysis are promising. However, significant work is still needed to couple condensed- and gas-phase reaction networks.

Synergy of Lewis and Br\xf8nsted acids on catalytic hydrothermal decomposition of carbohydrates and corncob acid hydrolysis residues to 5-hydroxymethylfurfural

5-hydroxymethylfurfural (HMF) is an important platform molecule in the synthesis of various chemicals and materials. Herein, we reported a simple and effective dehydration of glucose-based carbohydrates to HMF in a biphasic system containing cyclopentyl methyl ether as the organic phase and AlCl3 with minute amounts of HCl as co-catalysts. The results showed that the mixed catalysts had a positive synergistic catalytic effect on glucose conversion to HMF compared with single AlCl3 or HCl catalyst. For glucose, the highest HMF yield of 54.5% was achieved at 175 °C for 20 min. More importantly, the optimal catalytic system was so efficient that it achieved one of the highest reported yields of HMF (30.5%) directly from corncob acid hydrolysis residues. Thus, the catalytic system can become a promising route for effective utilization of biomass in future biorefineries.

Experimental and Mechanistic Modeling of Fast Pyrolysis of Neat Glucose-Based Carbohydrates. 1. Experiments and Development of a Detailed Mechanistic Model

Fast pyrolysis of lignocellulosic biomass, utilizing moderate temperatures ranging from 400 to 600 °C, produces a primary liquid product (pyrolytic bio-oil), which is potentially compatible with existing petroleum-based infrastructure and can be catalytically upgraded to fuels and chemicals. In this work, experiments were conducted with a micropyrolyzer coupled to a gas chromatography–mass spectrometry/flame ionization detector system to investigate fast pyrolysis of neat cellulose and other glucose-based carbohydrates. A detailed mechanistic model building on our previous work was developed for fast pyrolysis of neat glucose-based carbohydrates by integrating updated findings obtained through experiments and theoretical calculations. The model described the decomposition of cellulosic polymer chains, reactions of intermediates, and formation of a range of low molecular weight compounds at the mechanistic level and specified each elementary reaction step in terms of Arrhenius parameters. The mechanistic model for fast pyrolysis of neat cellulose included 342 reactions of 103 species, which included 96 reactions of 67 species comprising the mechanistic model of neat glucose decomposition.

Experimental and Mechanistic Modeling of Fast Pyrolysis of Neat Glucose-Based Carbohydrates. 2. Validation and Evaluation of the Mechanistic Model

A computational framework based on continuous distribution kinetics was constructed to solve the mechanistic model that was developed for fast pyrolysis of glucose-based carbohydrates in the first part of this study [Zhou et al. Ind. Eng. Chem. Res. 2014, 53. DOI 10.1021/ie502259w]. Comparing modeling results with experimental yields from fast pyrolysis over a wide range of reaction conditions validates the model. Agreement between model yields of final pyrolysis products with experimental data of fast pyrolysis of cellulose at temperatures ranging from 400 to 600 °C and maltohexaose, cellobiose, and glucose at 500 °C showed that the mechanistic model was robust and extendable. In comparison to our previous model [Vinu, R.; Broadbelt, L. J. Energy Environ. Sci. 2012, 5, 9808–9826], the mechanistic model presented in this work incorporating new findings from experiments and theoretical calculations showed enhanced performance in capturing experimental yields of major products such as levoglucosan-pyranose,...

Thermogravimetric Analysis of Glucose-Based and Fructose-Based Carbohydrates

Thermogravimetric analysis (TGA) was employed to study the pyrolysis characteristics of four glucose-based and three fructose-based carbohydrates. Kinetic parameters were calculated based on the experiment data. The results indicated that the starting and maximal pyrolysis temperatures of the glucose-based carbohydrates were increased steadily as the rising of their degree of polymerization (DP). The fructose-based carbohydrates exhibited similar pyrolysis behaviors as the glucose-based carbohydrates, but the difference was smaller. Kinetic calculations revealed that the activation energy values of the glucose-based carbohydrates were higher than those of the fructose-based carbohydrates, indicating the glucose-based carbohydrates were more difficult to decompose than the fructose-based carbohydrates.

A mechanistic model of fast pyrolysis of glucose-based carbohydrates to predict bio-oil composition

Bio-oil obtained from fast pyrolysis of biomass has the potential to be upgraded to renewable, drop-in fuel intermediates. The quality of bio-oil produced is critical to downstream process development and is determined by a number of factors like reaction timescale, extent of primary and secondary reactions, and the presence of minerals. In this work, we provide a mechanistic understanding of the various competing reactions in fast pyrolysis of cellulose and other glucose-based carbohydrates through a unified microkinetic model. The model incorporates the reactions of the cellulose chain and of the glucose intermediate to form a variety of bio-oil components, which are confirmed by either experiments or theoretical calculations reported in the literature. The majority of the Arrhenius rate parameters were based on existing studies, while a small number were fitted to match the experimental product distribution over a wide range of temperatures. The model yields of all the major primary fast pyrolysis products, viz., levoglucosan, formic acid, glycolaldehyde, 5-hydroxymethyl furfural, furfural and char, match reasonably well with the experimental data over the temperature range of 400–550 °C. The model predicted that the time required for complete conversion corresponds to 2.5–3 s. Net rate analysis identified key pathways to levoglucosan via either mid-chain initiation, or depropagation and end-chain initiation that were dominant over the timescales of 0–100 ms and 100–1000 ms, respectively, at 500 °C. Unlike the existing lumped kinetic models, our model provides a detailed picture of levoglucosan formation that involves mid-chain glycosidic bond cleavage followed by unzipping of levoglucosan from the chain ends. The model, utilizing the same set of rate coefficients, was able to predict the dominant products of fast pyrolysis of maltohexaose, cellobiose and glucose that also are in good agreement with experimental data. The initial chain length of cellulose was found to have a profound effect on the product yields for chain lengths shorter than 50, while it had no effect on the total reaction time.

Direct conversion of carbohydrates to 5-hydroxymethylfurfural using Sn-Mont catalyst

5-Hydroxymethylfurfural (HMF) is a very important intermediate in the fine chemical industry. This study aims to investigate the direct conversion of glucose or glucose-based carbohydrates, such as sucrose, cellobiose, inulin, starch and cellulose, to HMF by using a Sn-Mont catalyst. With the use of this catalyst, a HMF yield of 53.5% was achieved from glucose in a mono-phase medium of tetrahydrofuran (THF)/dimethylsulfoxide (DMSO) at 160 °C for 3 h. The success of one-step conversion of glucose to HMF is attributed to the Sn-Mont catalyst containing two types of acid sites, Lewis acid and Bronsted acid sites. The former one plays a crucial role in the isomerization of glucose to fructose and the latter one is active in the dehydration of generated fructose to HMF. Furthermore, Sn-Mont catalyst also demonstrated excellent activity in the conversion of disaccharides and polysaccharides and as high as 39.1% HMF was directly obtained from cellulose in a THF/H2O–NaCl bi-phasic system.

Conversion of carbohydrates and lignocellulosic biomass into 5-hydroxymethylfurfural using AlCl3·6H2O catalyst in a biphasic solvent system

AlCl3·6H2O in a biphasic medium of water/tetrahydrofuran (THF) is effective for the synthesis of 5-hydroxymethylfurfural (HMF) from glucose-based carbohydrates. For glucose, an HMF yield of 61% was achieved in 10 min at 160 °C under microwave heating. The reaction time profile revealed the intermediacy of fructose en route to HMF with a dehydration rate constant that is approximately 4 times that of glucose isomerization to fructose. Addition of NaCl did not increase HMF yields significantly but it diminished lactic acid formation. Disaccharides (maltose and cellobiose) and starch gave good yields of HMF. However, cellulose required a higher temperature (180 °C) and longer reaction time (30 min) to give a modest yield of 37%. Several lignocellulosic biomass variants (corn stover, pine wood, grass, and poplar) were investigated with the AlCl3·6H2O biphasic system. The yields of HMF were modest (20–35%) but high concurrent yields of furfural were observed (51–66%). The described AlCl3·6H2O–NaCl–H2O/THF biphasic medium has potential because it is economic, nontoxic, and it exhibits fast kinetics (10 min) under microwave heating.