- A one-pot reaction for biorefinery: Combination of solid acid and base catalysts for direct production of 5-hydroxymethylfurfural from saccharides
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5-Hydroxymethylfurfural (HMF), one of the most important intermediates derived from biomass, was directly produced from monosaccharides (fructose and glucose) and disaccharides (sucrose and cellobiose) by a simple one-pot reaction including hydrolysis, isomerization and dehydration using solid acid and base catalysts under mild conditions.
- Takagaki, Atsushi,Ohara, Mika,Nishimura, Shun,Ebitani, Kohki
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- Uncatalysed wet oxidation of d-glucose with hydrogen peroxide and its combination with hydrothermal electrolysis
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An increasing interest in biomass as a renewable feedstock for the chemical industry has risen over the last decades, and glucose, the monomer unit of cellulose, has been widely studied as a source material to produce value-added products such as carboxylic acids, mainly gluconic and formic. In this work, the non-catalysed wet oxidation of glucose using hydrogen peroxide has been analysed, obtaining molar yields to gluconic and formic acids up to 15% and 64%, respectively. Glucose conversion was generally between 40 and 50%, reaching over 80% under the highest temperature (200°C). An appropriate choice of temperature can tune product distribution as well as reaction rates. The interaction of the wet oxidation with an electrolytic reaction was also analysed.
- Moreno, Teresa,Kouzaki, Goushi,Sasaki, Mitsuru,Goto, Motonobu,Cocero, María José
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- Sulfonic acid-functionalized carbon coated red mud as an efficient catalyst for the direct production of 5-HMF from D-glucose under microwave irradiation
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Though suitable for the fructose conversion to 5-hydroxymethylfurfural (5-HMF), sulfonated carbon catalysts are inefficient for the direct glucose transformation to 5-HMF due to the lack of appropriate Lewis acids. Here, we have reported an efficient and inexpensive catalyst by suitably modifying red mud (RM), a by-product from the aluminum industry. The AD-1:1/SO3H catalyst produced by the acid (HCl) treatment, carbon coating, and SO3H grafting on RM exhibited enhanced surface area, mesoporous characteristics, and suitable Lewis and Bronsted acid sites. The XRD, FTIR, and XPS analysis suggested Fe2(SO4)3, Fe2O3, and various carbon functionalities as the major active components in the AD-1:1/SO3H catalyst. The NH3-TPD analysis revealed an appreciable acid site density of 6.8 mmol g?1. Under microwave heating at 180 °C, 30 min, and 90:10 DMSO/water weight percentage ratio, the catalyst produced a D-glucose conversion and 5-HMF yield of 93.05 % and 51.5 %, respectively.
- Das, Bikashbindu,Mohanty, Kaustubha
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- Producing Glucose 6-phosphate from cellulosic biomass: Structural insights into levoglucosan bioconversion
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The most abundant carbohydrate product of cellulosic biomass pyrolysis is the anhydrosugar levoglucosan (1, 6-anhydro-β-D-glucopyranose), which can be converted to glucose 6-phosphate by levoglucosan kinase (LGK). In addition to the canonical kinase phosphotransfer reaction, the conversion requires cleavage of the 1, 6-anhydro ring to allow ATP-dependent phosphorylation of the sugar O6 atom. Using x-ray crystallography, we show that LGK binds two magnesium ions in the active site that are additionally coordinated with the nucleotide and water molecules to result in ideal octahedral coordination. To further verify the metal binding sites, we co-crystallized LGK in the presence of manganese instead of magnesium and solved the structure de novo using the anomalous signal from four manganese atoms in the dimeric structure. The first metal is required for catalysis, whereas our work suggests that the second is either required or significantly promotes the catalytic rate. Although the enzyme binds its sugar substrate in a similar orientation to the structurally related 1, 6-anhydro-N-acetylmuramic acid kinase (AnmK), it forms markedly fewer bonding interactions with the substrate. In this orientation, the sugar is in an optimal position to couple phosphorylation with ring cleavage. We also observed a second alternate binding orientation for levoglucosan, and in these structures, ADP was found to bind with lower affinity. These combined observations provide an explanation for the high Km of LGK for levoglucosan. Greater knowledge of the factors that contribute to the catalytic efficiency of LGK can be used to improve applications of this enzyme for levoglucosan-derived biofuel production.
- Bacik, John-Paul,Klesmith, Justin R.,Whitehead, Timothy A.,Jarboe, Laura R.,Unkefer, Clifford J.,Mark, Brian L.,Michalczyk, Ryszard
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- Free energy landscape for glucose condensation and dehydration reactions in dimethyl sulfoxide and the effects of solvent
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The mechanisms and free energy surfaces (FES) for the initial critical steps during proton-catalyzed glucose condensation and dehydration reactions were elucidated in dimethyl sulfoxide (DMSO) using Car-Parrinello molecular dynamics (CPMD) coupled with me
- Qian, Xianghong,Liu, Dajiang
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- Glucose to value-added chemicals: Anhydroglucose formation by selective dehydration over solid acid catalysts
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Selective dehydration of glucose to anhydroglucoses, 1,6-anhydro-β-D- glucopyranose (levoglucosan) and 1,6-anhydro-β-D-glucofuranose, which are highly value-added intermediates for drugs, polymers, and surfactants was performed. Solid acids with sulfonic acid groups like Amberlyst-15 were found to effectively produce anhydroglucoses in polar aprotic solvents. Copyright
- Takagaki, Atsushi,Ebitani, Kohki
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- Isotope labeling studies on the formation of 5-(hydroxymethyl)-2- furaldehyde (HMF) from sucrose by pyrolysis-GC/MS
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Although it is generally assumed that the reactivity of sucrose, a nonreducing sugar, in the Maillard reaction is due to its hydrolysis into free glucose and fructose, however, no direct evidence has been provided for this pathway, especially in dry and high temperature systems. Using specifically Relabeled sucrose at C-1 of the fructose moiety, HMF formation was studied at different temperatures. Under dry pyrolytic conditions and at temperatures above 250°C, 90% of HMF originated from fructose moiety and only 10% originated from glucose. Alternatively, when sucrose was refluxed in acidic methanol at 65°C, 100% of HMF was generated from the glucose moiety. Moreover, the relative efficiency of the known HMF precursor 3-deoxyglucosone to generate HMF was compared to that of glucose, fructose and sucrose. Glucose exhibited a much lower conversion rate than 3-deoxyglucosone, however, both fructose and sucrose showed much higher conversion rates than 3-deoxyglucosone thus precluding it as a major precursor of HMF in fructose and sucrose solutions. Based on the data generated, a mechanism of HMF formation from sucrose is proposed. According to this proposal sucrose degrades into glucose and a very reactive fructofuranosyl cation. In dry systems this cation can be effectively converted directly into HMF.
- Locas, Carolina Perez,Yaylayan, Varoujan A.
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- Syntheses of 5-hydroxymethylfurfural and levoglucosan by selective dehydration of glucose using solid acid and base catalysts
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Selective dehydration of glucose, the most abundant monosaccharide, was examined using a solid acid catalyst individually or a combination of solid acid and base catalysts to form anhydroglucose (levoglucosan) or 5-hydroxymethylfurfural (HMF), respectively. Glucose was dehydrated to anhydroglucose by acid catalysis in polar aprotic solvents including N,N-dimethylformamide. Amberlyst-15, a strongly acidic ion-exchange resin, functioned as an efficient solid acid catalyst for anhydroglucose production with high selectivity. In the presence of solid base, aldose-ketose isomerization of glucose to fructose preferentially occurred by base catalysis, even in coexistence with the solid acid, resulting in successive dehydration of fructose to 5-hydroxymethylfurfural by acid catalysis with high yield in a one-pot reaction. A combination of Amberlyst-15 and hydrotalcite, an anionic layered clay, afforded high HMF selectivity under a moderate reaction temperature, owing to prevention of anhydroglucose formation.
- Ohara, Mika,Takagaki, Atsushi,Nishimura, Shun,Ebitani, Kohki
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- Production of solubilized carbohydrate from cellulose using non-catalytic, supercritical depolymerization in polar aprotic solvents
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We report yields of solubilized and depolymerized carbohydrate from solvent processing of cellulose as high as 94% without use of catalysts. Cellulose was converted using a variety of polar aprotic solvents at supercritical conditions, including 1,4-dioxane, ethyl acetate, tetrahydrofuran, methyl iso-butyl ketone, acetone, acetonitrile, and gamma-valerolactone. Maximum yield of solubilized products from cellulose, defined as both depolymerized carbohydrate and products of carbohydrate dehydration, was 72 to 98% at 350 °C for reaction times of 8-16 min. In all cases solvents were recovered with high efficiency. Levoglucosan was the most prevalent solubilized carbohydrate product with yields reaching 41% and 34% in acetonitrile and gamma-valerolactone, respectively. Levoglucosan yields increased with increasing polar solubility parameter, corresponding to decreasing activation energy for cellulose depolymerization.
- Ghosh, Arpa,Brown, Robert C.,Bai, Xianglan
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- Biochemical Characterization and Mechanistic Analysis of the Levoglucosan Kinase from Lipomyces starkeyi
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Levoglucosan kinase (LGK) catalyzes the simultaneous hydrolysis and phosphorylation of levoglucosan (1,6-anhydro-β-d-glucopyranose) in the presence of Mg2+–ATP. For the Lipomyces starkeyi LGK, we show here with real-time in situ NMR spectroscopy at 10 °C and pH 7.0 that the enzymatic reaction proceeds with inversion of anomeric stereochemistry, resulting in the formation of α-d-glucose-6-phosphate in a manner reminiscent of an inverting β-glycoside hydrolase. Kinetic characterization revealed the Mg2+ concentration for optimum activity (20–50 mm), the apparent binding of levoglucosan (Km=180 mm) and ATP (Km=1.0 mm), as well as the inhibition by ADP (Ki=0.45 mm) and d-glucose-6-phosphate (IC50=56 mm). The enzyme was highly specific for levoglucosan and exhibited weak ATPase activity in the absence of substrate. The equilibrium conversion of levoglucosan and ATP lay far on the product side, and no enzymatic back reaction from d-glucose-6-phosphate and ADP was observed under a broad range of conditions. 6-Phospho-α-d-glucopyranosyl fluoride and 6-phospho-1,5-anhydro-2-deoxy-d-arabino-hex-1-enitol (6-phospho-d-glucal) were synthesized as probes for the enzymatic mechanism but proved inactive with the enzyme in the presence of ADP. The pyranose ring flip 4C1→1C4 required for 1,6-anhydro-product synthesis from d-glucose-6-phosphate probably presents a major thermodynamic restriction to the back reaction of the enzyme.
- Rother, Christina,Gutmann, Alexander,Gudiminchi, Ramakrishna,Weber, Hansj?rg,Lepak, Alexander,Nidetzky, Bernd
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- Applications of Shoda's reagent (DMC) and analogues for activation of the anomeric centre of unprotected carbohydrates
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2-Chloro-1,3-dimethylimidazolinium chloride (DMC, herein also referred to as Shoda's reagent) and its derivatives are useful for numerous synthetic transformations in which the anomeric centre of unprotected reducing sugars is selectively activated in aqueous solution. As such unprotected sugars can undergo anomeric substitution with a range of added nucleophiles, providing highly efficient routes to a range of glycosides and glycoconjugates without the need for traditional protecting group manipulations. This mini-review summarizes the development of DMC and some of its derivatives/analogues, and highlights recent applications for protecting group-free synthesis.
- Fairbanks, Antony J.
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- Unravelling the catalytic influence of naturally occurring salts on biomass pyrolysis chemistry using glucose as a model compound: A combined experimental and DFT study
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Fast pyrolysis is an efficient thermochemical decomposition process to produce bio-oil and renewable chemicals from lignocellulosic biomass. It has been suggested that alkali- and alkaline-earth metal (AAEM) ions in biomass alter the yield and composition of bio-oil, but little is known about the intrinsic chemistry of metal-catalyzed biomass pyrolysis. In this study, we combined thin-film pyrolysis experiments and density functional theory (DFT) calculations to obtain insights into AAEM-catalyzed glucose decomposition reactions, especially forming major bio-oil components and char. Experiments reveal the difference in the yield and composition of bio-oil of metal-free and AAEM complexed glucose. Metal-free glucose produced 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DHMDHP) as the predominant compound in bio-oil, while 1,6-anhydroglucofuranose (AGF) was dominant in Na(i)/glucose, levoglucosan (LGA) in K(i)/glucose, levoglucosenone (LGO) in Ca(ii)/glucose and furfural in Mg(ii)/glucose. To evaluate the stereoelectronic basis of metal ions in altering pyrolysis reaction kinetics, the reaction mechanisms of AGF, LGA, 5-hydroxymethylfurfural (5-HMF), furfural, 1,5-anhydro-4-deoxy-d-glycerohex-1-en-3-ulose (ADGH), LGO, and char formation were investigated using DFT calculations. DFT results showed that the presence of Ca(ii) and Mg(ii) ions catalyzed furfural and LGO formation, while alkali ions decatalyzed the formation of these products. Conversely, Na(i) and K(i) ions catalyzed the concerted dehydrative ring closure of glucofuranose during AGF formation. For ADGH, AAEMs showed an anti-catalytic effect. We also described a novel route for char formation via coupling between 1,2-anhydroglucopyranose and a carbonyl compound. The presence of alkali ions catalyzed char formation. Thus, the atomistic insights obtained from DFT calculations assist in understanding the observed change in experimental yields of individual bio-oil compounds governing their composition.
- Arora, Jyotsna S.,Ansari, Khursheed B.,Chew, Jia Wei,Dauenhauer, Paul J.,Mushrif, Samir H.
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p. 3504 - 3524
(2019/07/09)
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- Carbon Materials as Phase-Transfer Promoters for Obtaining 5-Hydroxymethylfurfural from Cellulose in a Biphasic System
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Different carbonaceous materials were tested as mass-transfer promoters for increasing the yield of 5-hydroxymethylfurfural (5-HMF) in biphasic cellulose hydrolysis. The benefits of working with a biphasic system (water/methyl isobutyl ketone) under soft acid conditions were taken as starting point (no humins or levulinic acid production), with slow extraction kinetics as the weakest point of this approach. Carbon nanotubes (CNTs) and activated carbon (AC) were proposed to improve 5-HMF liquid–liquid mass transfer. A kinetic analysis of the extraction process indicated the competition between 5-HMF and glucose adsorption as the main cause of the poor results obtained with AC. In contrast, very promising results were obtained with CNTs, mainly at 1.5 wt % loading, with complete transfer of HMF and a high global mass-transfer coefficient. The use of CNTs improved the amount of 5-HMF in the organic phase by more than 270 %.
- Faba, Laura,Garcés, Diego,Díaz, Eva,Ordó?ez, Salvador
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p. 3769 - 3777
(2019/07/04)
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- Method for synthesizing intermediate of fondaparinux sodium
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The invention discloses a method for synthesizing an intermediate of fondaparinux sodium represented by a formula 1. The method comprises the step of subjecting a compound represented by a formula 2 and benzaldehyde, which serve as reaction raw materials, to acetal protective reaction and diacetyl removing reaction in an organic solvent in the presence of mixed acid, thereby obtaining the intermediate of fondaparinux sodium represented by the formula 1 in one step, wherein the mixed acid is prepared from concentrated sulfuric acid and para-toluenesulfonic acid which are in the mass ratio of 1to (0.1 to 5), the concentrated sulfuric acid is a sulfuric acid aqueous solution with the mass fraction of 70% to 98%, the organic solvent contains toluene, of which the volume accounts for 5% to 15%that of the organic solvent; a volume ratio of water to the organic solvent in an initial reaction system is controlled to (0.005 to 0.04) to 1. The method has the advantages of being high in conversion ratio, high in reaction rate, simple in operation and applicable to large-scale production. The formula 1 and formula 2 are shown in the description.
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Paragraph 0033; 0066-0068
(2018/03/26)
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- Glycosyl Bunte Salts: A Class of Intermediates for Sugar Chemistry
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S-Glycosyl thiosulfates have been discovered as a new class of synthetic intermediates in sugar chemistry, named "glycosyl Bunte salts" after 19th-century German chemist, Hans Bunte. The synthesis was achieved by direct condensation of unprotected sugars and sodium thiosulfate using a formamidine-type dehydrating agent in water-acetonitrile mixed solvent. The application of glycosyl Bunte salts is demonstrated with transformation reactions into other glycosyl compounds such as a 1-thio sugar, a glycosyl disulfide, a 1,6-anhydro sugar, and an O-glycoside.
- Meguro, Yasuhiro,Noguchi, Masato,Li, Gefei,Shoda, Shin-Ichiro
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- Synergetic Effect of Br?nsted/Lewis Acid Sites and Water on the Catalytic Dehydration of Glucose to 5-Hydroxymethylfurfural by Heteropolyacid-Based Ionic Hybrids
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The effective dehydration of glucose to 5-hydroxymethylfurfural (HMF) has attracted increasing attention. Herein, a series of sulfonic-acid-functionalized ionic liquid (IL)–heteropolyacid (HPA) hybrid catalysts are proposed for the conversion of glucose to HMF. A maximum total yield of HMF and levoglucosan (LGA; ≈71 %) was achieved in the presence of pyrazine IL-HPA hybrid catalyst [PzS]H2PW in THF/H2O–NaCl (v/v 5:1). The mechanism of glucose dehydration was studied by tailoring the Br?nsted/Lewis acid sites of the hybrid catalysts and altering the solvent composition. It was found that water and heteropolyanions have a significant effect on the reaction kinetics. Heteropolyanions are able to stabilize the intermediates and promote the direct dehydration of glucose and intermediate LGA to HMF. A small amount of water could facilitate the conversion of glucose to LGA and suppress the dehydration of LGA to levoglucosenone. In addition, the synergetic effect of Br?nsted/Lewis acid sites and a little water was conducive to accelerated proton transfer, which improved the yield of HMF from glucose dehydration.
- Zhao, Pingping,Cui, Hongyou,Zhang, Yunyun,Zhang, Yuan,Wang, Yong,Zhang, Yali,Xie, Yujiao,Yi, Weiming
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p. 824 - 832
(2018/10/31)
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- PURE HEPTASULFATED DISACCHARIDES HAVING IMPROVED ORAL BIOAVAILABILITY
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Hypersulfated disaccharides with utility in asthma or asthma related disorders are disclosed. The heptasulfated disaccharides administered orally have comparable bioavailability to the intravenous administered dosage form.
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- Protecting group free synthesis of glycosyl thiols from reducing sugars in water; application to the production of N-glycan glycoconjugates
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Glycosyl thiols may be accessed from the corresponding reducing sugars in water without recourse to any sugar projecting groups by way of a DMC mediated reaction with thioacetic acid in the presence of base, and hydrolysis of the anomeric thioacetate. Glycosyl thiols produced by this method may be used to access glycoconjugates, such as glycopeptides by use of the thiol-ene click reaction.
- Alexander,Lim,Amso,Brimble,Fairbanks
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p. 2152 - 2156
(2017/03/20)
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- Production of levoglucosenone and 5-hydroxymethylfurfural from cellulose in polar aprotic solvent-water mixtures
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We demonstrate a process to produce levoglucosenone (LGO) and 5-hydroxymethylfurfural (HMF) from cellulose in up to 65% carbon yield using sulfuric acid as catalyst and a solvent consisting of a mixture of tetrahydrofuran (THF) with water. In pure THF, LGO is the major product of cellulose dehydration, passing through levoglucosan as an intermediate. Increasing the water content (up to 5 wt%) results in HMF as the major product. HMF is formed both by glucose dehydration and direct dehydration of LGA. The maximum combined yield of LGO and HMF (～65 carbon%) is achieved in the presence of 1-2.5 wt% H2O, such that comparable amounts of these two co-products are formed. THF gave the highest total yields of LGO and HMF among the solvents investigated in this study (i.e., THF, diglyme, tetraglyme, gamma-valerolactone (GVL), cyclopentyl methyl ether (CPME), 1,4-dioxane, and dimethyl sulfoxide (DMSO)). Furthermore, the rate of LGO and HMF degradation in THF was lower than in the other solvents. LGO/HMF yields increased with increased strength of the acid catalyst (H2SO4 > H3PO4 > HCOOH), and HMF was produced more selectively than LGO in the presence of hydrochloric acid. Techno-economic analysis for LGO and HMF production from cellulose shows that the lowest LGO/HMF production costs are less than $3.00 per kg and occur at a cellulose loading and water content of 2-3% and 1.5-2.5% respectively.
- He, Jiayue,Liu, Mingjie,Huang, Kefeng,Walker, Theodore W.,Maravelias, Christos T.,Dumesic, James A.,Huber, George W.
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p. 3642 - 3653
(2017/08/09)
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- Catalytic conversion of glucose into alkanediols over nickel-based catalysts: A mechanism study
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The conversion of isotope-labeled glucose (d-1-13C-glucose) into alkanediols was carried out in a batch reactor over a Ni-MgO-ZnO catalyst to reveal the C-C cleavage mechanisms. The unique role of the MgO-ZnO support was highlighted by 13C NMR and GC-MS analysis qualitatively and the MgO-ZnO favored isomerization of glucose to fructose. 13C NMR, GC-MS and HPLC analysis demonstrated that the C1 position of ethylene glycol, the C1 and C3 positions of 1,2-propanediol and the C1 position of glycerin were labeled with 13C, which is attributed to a C-C cleavage at d-1-13C-glucose's corresponding positions through retro-aldol condensation. A hydrogenolysis followed by hydrogenation pathway was proposed for glucose converted into alkanediols at 493 K with 6.0 MPa of H2 pressure over Ni based catalysts.
- Tan, Zhichao,Miao, Gai,Liu, Chang,Luo, Hu,Bao, Liwei,Kong, Lingzhao,Sun, Yuhan
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p. 62747 - 62753
(2016/07/13)
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- Catalytic fast pyrolysis of cellulose using nano zeolite and zeolite/matrix catalysts in a GC/micro-pyrolyzer
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Cellulose, as a model compound of biomass, was catalyzed over zeolite (HY, HZSM-5) and zeolite/matrix (HY/Clay, HM/Clay) in a GC/micro-pyrolyzer at 500 °C, to produce the valuable products. The catalysts used were pure zeolite and zeolite/matrix including 20 wt% matrix content, which were prepared into different particle sizes (average size; 0.1 mm, 1.6 mm) to study the effect of the particle size of the catalyst for the distribution of product yields. Catalytic pyrolysis had much more volatile products as light components and less content of sugars than pyrolysis only. This phenomenon was strongly influenced by the particle size of the catalyst in catalytic fast pyrolysis. Also, in zeolite and zeolite/matrix catalysts the zeolite type gave the dominant impact on the distribution of product yields.
- Lee, Kyong-Hwan
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p. 4631 - 4637
(2016/06/01)
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- Aqueous Glycosylation of Unprotected Sucrose Employing Glycosyl Fluorides in the Presence of Calcium Ion and Trimethylamine
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We report a synthetic glycosylation reaction between sucrosyl acceptors and glycosyl fluoride donors to yield the derived trisaccharides. This reaction proceeds at room temperature in an aqueous solvent mixture. Calcium salts and a tertiary amine base promote the reaction with high site-selectivity for either the 3′-position or 1′-position of the fructofuranoside unit. Because nonenzymatic aqueous oligosaccharide syntheses are underdeveloped, mechanistic studies were carried out in order to identify the origin of the selectivity, which we hypothesized was related to the structure of the hydroxyl group array in sucrose. The solution conformation of various monodeoxysucrose analogs revealed the co-operative nature of the hydroxyl groups in mediating both this aqueous glycosyl bond-forming reaction and the site-selectivity at the same time.
- Pelletier, Guillaume,Zwicker, Aaron,Allen, C. Liana,Schepartz, Alanna,Miller, Scott J.
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supporting information
p. 3175 - 3182
(2016/03/19)
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- Mass spectrometric studies of fast pyrolysis of cellulose
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A fast pyrolysis probe/linear quadrupole ion trap mass spectrometer combination was used to study the primary fast pyrolysis products (those that first leave the hot pyrolysis surface) of cellulose, cellobiose, cellotriose, cellotetraose, cellopentaose, and cellohexaose, as well as of cellobiosan, cellotriosan, and cellopentosan, at 600°C. Similar products with different branching ratios were found for the oligosaccharides and cellulose, as reported previously. However, identical products (with the exception of two) with similar branching ratios were measured for cellotriosan (and cellopentosan) and cellulose. This result demonstrates that cellotriosan is an excellent small-molecule surrogate for studies of the fast pyrolysis of cellulose and also that most fast pyrolysis products of cellulose do not originate from the reducing end. Based on several observations, the fast pyrolysis of cellulose is suggested to initiate predominantly via two competing processes: The formation of anhydro-oligosaccharides, such as cellobiosan, cellotriosan, and cellopentosan (major route), and the elimination of glycolaldehyde (or isomeric) units from the reducing end of oligosaccharides formed from cellulose during fast pyrolysis.
- Degenstein, John C.,Hurt, Matt,Murria, Priya,Easton, McKay,Choudhari, Harshavardhan,Yang, Linan,Riedeman, James,Carlsen, Mark S.,Nash, John J.,Agrawal, Rakesh,Nicholas Delgass,Ribeiro, Fabio H.,Kentt?maa, Hilkka I.
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p. 321 - 326
(2016/03/25)
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- Catalytic conversion of glucose to 5-hydroxymethyl-furfural with a phosphated TiO2 catalyst
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Nanosized phosphated TiO2 catalysts with different phosphate contents were synthesized and tested for the conversion of glucose to 5-hydroxymethylfurfural. The resulting materials were characterized by using N2-adsorption, XRD, inductively coupled plasma atomic emission spectroscopy, X-ray spectroscopy, TEM, temperature-programmed desorption of ammonia, and FTIR spectroscopy of pyridine adsorption techniques to determine their structural, bulk, surface, and acid properties. We found that TiO2 nanoparticles catalyzed this reaction under mild conditions in a water-butanol biphasic system. The incorporation of phosphorus into the TiO2 framework remarkably enhances the target product selectivity, which is ascribed to increased surface area, enhanced acidity, as well as thermal stability resulting from the Ti-O-P bond formation. Under optimal reaction conditions, phosphated TiO2 was found to exhibit excellent catalytic performance, which resulted in 97-% glucose conversion and 81-% HMF yield after 3 h of reaction at 175-°C. More importantly, the catalyst showed good stability and could be reused for several reaction cycles. A moment of truth: The as-synthesized nanosized phosphated TiO2 material serves as a bifunctional catalyst in the production of 5-hydroxymethylfurfural (HMF) from glucose. The relationship between catalyst synthesis, properties, and performance indicates a high potential of the TiO2-based catalyst for HMF production. This provides a step further toward a sustainable route to generate HMF from renewable carbohydrate feedstock.
- Atanda, Luqman,Mukundan, Swathi,Shrotri, Abhijit,Ma, Qing,Beltramini, Jorge
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p. 781 - 790
(2015/03/04)
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- β-Selective C-Arylation of Diisobutylaluminum Hydride Modified 1,6-Anhydroglucose: Synthesis of Canagliflozin without Recourse to Conventional Protecting Groups
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The β-selective phenylation of benzyl and boronate protected 1,6-anhydroglucose and the direct phenylation of unprotected 1,6-anhydroglucose (10), pretreated with i-Bu2AlH, i-Bu3Al, Et3Al, Me3Al, or n-octyl3Al, with triphenylalane or aryl(chloro)alanes is reported. The utility of the unprotected version of the method is demonstrated by the synthesis of the SGLT2 inhibitor, canagliflozin (1a), from commercially available 10 in one C-C bond-forming step. This approach circumvents the need for conventional protecting groups, and therefore no formal protection and deprotection steps are required. (Chemical Presented).
- Henschke, Julian P.,Lin, Chen-Wei,Wu, Ping-Yu,Tsao, Wen-Shing,Liao, Jyh-Hsiung,Chiang, Pei-Chen
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supporting information
p. 5189 - 5195
(2015/05/27)
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- Fast pyrolysis of 13c-labeled cellobioses: Gaining insights into the mechanisms of fast pyrolysis of carbohydrates
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A fast-pyrolysis probe/tandem mass spectrometer combination was utilized to determine the initial fast-pyrolysis products for four different selectively 13C-labeled cellobiose molecules. Several products are shown to result entirely from fragmentation of the reducing end of cellobiose, leaving the nonreducing end intact in these products. These findings are in disagreement with mechanisms proposed previously. Quantum chemical calculations were used to identify feasible low-energy pathways for several products. These results provide insights into the mechanisms of fast pyrolysis of cellulose.
- Degenstein, John C.,Murria, Priya,Easton, McKay,Sheng, Huaming,Hurt, Matt,Dow, Alex R.,Gao, Jinshan,Nash, John J.,Agrawal, Rakesh,Delgass, W. Nicholas,Ribeiro, Fabio H.,Kentt?maa, Hilkka I.
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p. 1909 - 1914
(2015/02/19)
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- OSDA-Free Zeolite Beta with High Aluminum Content Efficiently Catalyzes a Tandem Reaction for Conversion of Glucose to 5-Hydroxymethylfurfural
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Organic structure-directing agent (OSDA)-free zeolite Beta with high Al content exhibit remarkably high catalytic performance in the conversion of glucose to 5-hydroxymethylfurfural (HMF) by virtue of their appropriate acid properties; specifically, a sufficient number of Lewis acid sites were generated by calcination of the NH4-form zeolite, while the original Bronsted acid sites were substantially maintained, with both acid sites being in close proximity. The OSDA-free Beta catalyst, having a large number of Bronsted acid sites and sufficient Lewis acid sites, showed superior catalytic performance to a physical mixture of each type of acid catalyst with a similar number of each acid site. This behavior could be ascribed to the high reactivity and slow intrazeolitic diffusion of fructose. The structure of the Al species active in the isomerization of glucose to fructose is discussed based on relationships between catalytic activities and changes in Al species by the calcination, changes that were observed by 27Al magic-angle spinning (MAS) NMR and IR spectroscopies. Lewis and Bronsted, working together: Organic structure-directing agent (OSDA)-free zeolite Beta with high Al content effectively promotes conversion of glucose to 5-hydroxymethylfurfural (HMF). The high aluminum content of the zeolite provides suitable acid properties; specifically, a large number of Bronsted acid sites with a sufficient number of Lewis acid sites in close proximity. The zeolite calcined at 773 K showed >70 % yield of HMF.
- Otomo, Ryoichi,Yokoi, Toshiyuki,Tatsumi, Takashi
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p. 4180 - 4187
(2015/12/26)
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- Glucose dehydration to 5-hydroxymethylfurfural by a combination of a basic zirconosilicate and a solid acid
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A recently reported layered zirconosilicate Na2ZrSi4O11 displays good activity in the isomerization of glucose to fructose in water at mild conditions. Part of the activity derives from the homogeneous base-catalyzed reaction due to exchange of the sodium ions of the layered zirconosilicate in water. Following ion-exchange, the isomerization is mainly catalyzed by the basic sites of the re-used heterogeneous zirconosilicate catalyst. Combined with the solid acid Amberlyst-15, 5-hydroxymethylfurfural (5-HMF) can be produced from glucose in a one-pot reaction. In a THF/H2O mixture solvent system, 5-HMF was obtained with 45 % selectivity at 87 % glucose conversion at a temperature of 180 °C in 1.5 h. Graphical Abstract: [Figure not available: see fulltext.]
- Yue, Chaochao,Rigutto, Marcello S.,Hensen, Emiel J. M.
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p. 2121 - 2128
(2015/02/19)
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- Selective conversion of cellulose to hydroxymethylfurfural in polar aprotic solvents
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Herein, we report a new reaction pathway to produce hydroxymethylfurfural (HMF) from cellulose under mild reaction conditions (140-190°C; 5 mM H 2SO4) in polar aprotic solvents (i.e. THF) without the presence of water. In this system, levoglucosan is the major decomposition product of cellulose, followed by dehydration to produce HMF. Glucose, levulinic acid, and formic acid are also produced as a result of side reactions with water, which is a by-product of dehydration. The turnover frequency for cellulose conversion increases as the water content in the solvent decreases, with conversion rates in THF being more than twenty times higher than those in water. The highest HMF yield from cellulose was 44% and the highest combined yield of HMF and levulinic from cellulose was 53%, which are nearly comparable to yields obtained in ionic liquids or biphasic systems. Moreover, the use of a low boiling point solvent, such as THF, facilitates recovery of HMF in downstream processes.
- Weingarten, Ronen,Rodriguez-Beuerman, Alexandra,Cao, Fei,Luterbacher, Jeremy S.,Alonso, David Martin,Dumesic, James A.,Huber, George W.
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p. 2229 - 2234
(2014/08/18)
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- Catalytic conversion of fructose, glucose, and sucrose to 5-(hydroxymethyl)furfural and levulinic and formic acids in γ- valerolactone as a green solvent
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The conversion of fructose, glucose, and sucrose to 5-(hydroxymethyl) furfural (HMF) and levulinic acid (LA)/formic acid (FA) was investigated in detail using sulfuric acid as the catalyst and γ-valerolactone (GVL) as a green solvent. The H2SO4/GVL/H2O system can be tuned to produce either HMF or LA/FA by changing the acid concentration and thus allowing selective switching between the products. Although the best yields of HMF were around 75%, the LA/FA yields ranged from 50% to 70%, depending on the structure of the carbohydrates and the reaction parameters, including temperature, acid, and carbohydrate concentrations. While the conversion of fructose is much faster than glucose, sucrose behaves like a 1:1 mixture of fructose and glucose, indicating facile hydrolysis of the glycosidic bond in sucrose. The mechanism of the conversion of glucose to HMF or LA/FA in GVL involves three intermediates: 1,6-anhydro-β-d-glucofuranose, 1,6-anhydro-β-d-glucopyranose, and levoglucosenone.
- Qi, Long,Mui, Yiu Fung,Lo, See Wing,Lui, Matthew Y.,Akien, Geoffrey R.,Horvath, Istvan T.
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p. 1470 - 1477
(2014/05/20)
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- Catalytic conversion of cellulose over mesoporous y zeolite
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Mesoporous Y zeolite (Meso-Y) was applied, for the first time, to the catalytic pyrolysis of cellulose which is a major constituent of lignocellulosic biomass, to produce high-quality bio-oil. A representative mesoporous catalyst Al-MCM-41 was also used t
- Park, Young-Kwon,Jun, Bo Ram,Park, Sung Hoon,Jeon, Jong-Ki,Lee, See Hoon,Kim, Seong-Soo,Jeong, Kwang-Eun
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p. 5120 - 5123
(2014/07/21)
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- High-pressure fast-pyrolysis, fast-hydropyrolysis and catalytic hydrodeoxygenation of cellulose: Production of liquid fuel from biomass
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A lab-scale, high-pressure, continuous-flow fast-hydropyrolysis and vapor-phase catalytic hydrodeoxygenation (HDO) reactor has been successfully designed, built and tested with cellulose as a model biomass feedstock. We investigated the effects of pyrolysis temperature on high-pressure cellulose fast-pyrolysis, hydrogen on high-pressure cellulose fast-hydropyrolysis, reaction pressure (27 bar and 54 bar) on our reactor performance and candidate catalysts for downstream catalytic HDO of cellulose fast-hydropyrolysis vapors. In this work, a liquid chromatography-mass spectrometry (LC-MS) method has been developed and utilized for quantitative characterization of the liquid products. The major compounds in the liquid from cellulose fast-pyrolysis (27 bar, 520 °C) are levoglucosan and its isomers, formic acid, glycolaldehyde, and water, constituting 51 wt%, 11 wt%, 8 wt% and 24 wt% of liquid respectively. Our results show that high pressures of hydrogen do not have a significant effect on the fast-hydropyrolysis of cellulose at 480 °C but suppress the formation of reactive light oxygenate species like glycolaldehyde and formic acid at 580 °C. The formation of permanent gases (CO, CO2, CH4) and glycolaldehyde and formic acid increased with increasing pyrolysis temperature in the range of 480 °C-580 °C in high-pressure cellulose fast-pyrolysis, in the absence of hydrogen. Candidate HDO catalysts Al 2O3, 2% Ru/Al2O3 and 2% Pt/Al 2O3 resulted in extents of deoxygenation of 20%, 22% and 27%, respectively, but led to carbon loss to gas phase as CO and CH4. These catalysts provide useful insights for other candidate HDO catalysts for improving the extent of deoxygenation with higher carbon recovery in the liquid product.
- Venkatakrishnan, Vinod Kumar,Degenstein, John C.,Smeltz, Andrew D.,Delgass, W. Nicholas,Agrawal, Rakesh,Ribeiro, Fabio H.
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p. 792 - 802
(2014/02/14)
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- Total synthesis of herbicidin C and aureonuclemycin: Impasses and new avenues
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The undecose nucleoside antibiotics herbicidin C and aureonuclemycin are biologically highly active and represent challenging targets for total synthesis. Herein, the gradual evolution of our synthetic strategy toward these natural products is described in detail. The initial route encompasses metalate addition chemistry but suffers from poor stereochemical control. In contrast, the ultimately successful strategy benefits from a variety of reagent-controlled stereoselective transformations, including a surprisingly facile and highly diastereoselective N-glycosylation process. The presented work also describes new building blocks that might find further application in carbohydrate chemistry.
- Hager, Dominik,Paulitz, Christian,Tiebes, Joerg,Mayer, Peter,Trauner, Dirk
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p. 10784 - 10801
(2013/11/19)
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- Direct microwave-assisted hydrothermal depolymerization of cellulose
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A systematic investigation of the interaction of microwave irradiation with microcrystalline cellulose has been carried out, covering a broad temperature range (150 → 270°C). A variety of analytical techniques (e.g., HPLC, 13C NMR, FTIR, CHN analysis, hydrogen-deuterium exchange) allowed for the analysis of the obtained liquid and solid products. Based on these results a mechanism of cellulose interaction with microwaves is proposed. Thereby the degree of freedom of the cellulose enclosed CH2OH groups was found to be crucial. This mechanism allows for the explanation of the different experimental observations such as high efficiency of microwave treatment; the dependence of the selectivity/yield of glucose on the applied microwave density; the observed high glucose to HMF ratio; and the influence of the degree of cellulose crystallinity on the results of the hydrolysis process. The highest selectivity toward glucose was found to be ～75% while the highest glucose yield obtained was 21%.
- Fan, Jiajun,De Bruyn, Mario,Budarin, Vitaliy L.,Gronnow, Mark J.,Shuttleworth, Peter S.,Breeden, Simon,Macquarrie, Duncan J.,Clark, James H.
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supporting information
p. 12728 - 12731
(2013/09/02)
-
- A stepwise solvent-promoted SNi reaction of α-d- glucopyranosyl fluoride: Mechanistic implications for retaining glycosyltransferases
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The solvolysis of α-d-glucopyranosyl fluoride in hexafluoro-2- propanol gives two products, 1,1,1,3,3,3-hexafluoropropan-2-yl α-d-glucopyranoside and 1,6-anhydro-β-d-glucopyranose. The ratio of these two products is essentially unchanged for reactions that are performed between 56 and 100 °C. The activation parameters for the solvolysis reaction are as follows: ΔH? = 81.4 ± 1.7 kJ mol -1, and ΔS? = -90.3 ± 4.6 J mol -1 K-1. To characterize, by use of multiple kinetic isotope effect (KIE) measurements, the TS for the solvolysis reaction in hexafluoro-2-propanol, we synthesized a series of isotopically labeled α-d-glucopyranosyl fluorides. The measured KIEs for the C1 deuterium, C2 deuterium, C5 deuterium, anomeric carbon, ring oxygen, O6, and solvent deuterium are 1.185 ± 0.006, 1.080 ± 0.010, 0.987 ± 0.007, 1.008 ± 0.007, 0.997 ± 0.006, 1.003 ± 0.007, and 1.68 ± 0.07, respectively. The transition state for the solvolysis reaction was modeled computationally using the experimental KIE values as constraints. Taken together, the reported data are consistent with the retained solvolysis product being formed in an SNi (DN? A Nss) reaction with a late transition state in which cleavage of the glycosidic bond is coupled to the transfer of a proton from a solvating hexafluoro-2-propanol molecule. In comparison, the inverted product, 1,6-anhydro-β-d-glucopyranose, is formed by intramolecular capture of a solvent-equilibrated glucopyranosylium ion, which results from dissociation of the solvent-separated ion pair formed in the rate-limiting ionization reaction (DN? + AN). The implications that this model reaction have for the mode of action of retaining glycosyltransferases are discussed.
- Chan, Jefferson,Tang, Ariel,Bennet, Andrew J.
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supporting information; experimental part
p. 1212 - 1220
(2012/03/12)
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- Method for conversion of carbohydrate polymers to value-added chemical products
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Methods are described for conversion of carbohydrate polymers in ionic liquids, including cellulose, that yield value-added chemicals including, e.g., glucose and 5-hydroxylmethylfurfural (HMF) at temperatures below 120° C. Catalyst compositions that include various mixed metal halides are described that are selective for specified products with yields, e.g., of up to about 56% in a single step process.
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-
Page/Page column 9-10
(2012/02/14)
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- Catalytic fast pyrolysis of cellulose to prepare levoglucosenone using sulfated zirconia
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Sulfated zirconia was employed as catalyst for fast pyrolysis of cellulose to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The yield and the selectivity of LGO were studied in a fixed-bed reactor at different temperatures and cellulose/catalyst mass ratios. The experiments of catalyst recycling were also carried out. The results displayed that from 290 to 400 °C, the liquid and solid accounted for more than 95 wt % of products, and the higher temperature led to more liquid and less solid products. The introduction of SO42-/ZrO2 could promote cellulose conversion and LGO production. The temperature had a similar effect on the yield and selectivity of LGO at different cellulose/catalyst mass ratios. The maximum yield was obtained at 335 °C. Although the structure of the parent ZrO2 was retained after recycles, which was confirmed by X-ray diffraction and N2 adsorption-desorption measurements, the activity of SO42-/ZrO2 could only be partially recovered by simply calcination. The catalytic activity decrease could be mainly attributed to SO42- leaching, and the activity could be restored by further impregnation of H2SO4. It′s not diamond, it′s zirconia: SO42-/ZrO2 is an efficient catalyst for the production of levoglucosenone by fast pyrolysis of cellulose admixing catalysts. The optimal temperature for preparation of levoglucosenone is in the range of 320-350 °C. In the presence of the SO42-/ZrO2, the levoglucosenone content of pyrolysis liquid is greatly increased at 335 °C compared to pure cellulose.
- Wang, Zhi,Lu, Qiang,Zhu, Xi-Feng,Zhang, Ying
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experimental part
p. 79 - 84
(2012/01/06)
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- Reductive splitting of cellulose in the ionic liquid 1-butyl-3-methylimidazolium chloride
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The depolymerization of cellulose is carried out in the ionic liquid 1-butyl-3-methylimidazolium chloride in the presence of hydrogen gas. First, the ketal 1,1-diethoxycyclohexane and cel-lobiose were used as model substrates. For the depolymerization of cellulose itself, the combination of a heterogeneous metal catalyst and a homogeneous ruthenium catalyst proved effective. One of the possible roles of the ruthenium compound is to enhance the transfer of hydrogen to the metallic surface. The cellulose is fully converted under relatively mild conditions, with sorbitol as the dominant product in 51-74% yield.
- Ignatyev, Igor A.,Doorslaer, Charlie Van,Mertens, Pascal G. N.,Binnemans, Koen,De Vos, Dirk E.
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scheme or table
p. 91 - 96
(2011/02/22)
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- Cellulose conversion into alkylglycosides in the ionic liquid 1-butyl-3-methylimidazolium chloride
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The conversion of cellulose into alkylglycosides is carried out in the ionic liquid 1-butyl-3-methylimidazolium chloride in the presence of an acidic catalyst. Primary alcohols like n-butanol and n-octanol were used as alkylating reagents. The acidic resin Amberlyst 15DRY proved to be the optimum heterogeneous catalyst: it catalyzes the hydrolysis of the β(1→4) links in the cellulose polymeric chain as well as the alkylation of the hydroxyl groups at the C1 position of the glucose intermediate. The cellulose was fully converted under mild conditions; in a reaction with n-butanol, the obtained yield of butylglucopyranoside isomers was 86%.
- Ignatyev, Igor A.,Mertens, Pascal G. N.,Van Doorslaer, Charlie,Binnemans, Koen,De Vos, Dirk E.
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scheme or table
p. 1790 - 1795
(2011/02/21)
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- Mechanocatalysis for biomass-derived chemicals and fuels
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Heterogeneous catalysis cannot be easily applied to solids such as cellulose. However, by mechanically grinding the correct catalyst and reactant, it is possible to induce solid-solid catalysis or mechanocatalysis. This process allows a wide range of solids to be effectively utilized as feedstock for commercially relevant compounds. Here we show a set of structural and physical parameters important for the implementation of catalysts in mechanocatalytic processes and their application in the catalytic depolymerization of cellulose. Using the best catalysts, which possess high surface acidities and layered structures, up to 84% of the available cellulose can be converted to water-soluble compounds in a single pass. This approach offers significant advantages over current methods - less waste, insensitivity to feedstock, multiple product pathways, and scalability. It can be easily integrated into existing biorefineries - converting them into multi-feedstock and multi-product facilities. This will expand the use of non-food polysaccharide sources such as switch grass.
- Hick, Sandra M.,Griebel, Carolin,Restrepo, David T.,Truitt, Joshua H.,Buker, Eric J.,Bylda, Caroline,Blair, Richard G.
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experimental part
p. 468 - 474
(2010/08/06)
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- Direct synthesis of 1,6-anhydro sugars from unprotected glycopyranoses by using 2-chloro-1,3-dimethylimidazolinium chloride
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Various 1,6-anhydro sugars have been synthesized directly from the corresponding unprotected glycopyranoses in excellent yields by using 2-chloro-1,3-dimethylimidazolinium chloride (DMC) as a dehydrative condensing agent. The reactions took place smoothly under mild reaction conditions in aqueous media. The present method would be a practical tool for synthesis of 1,6-anhydro derivatives of monosaccharides, linear-oligosaccharides, and branched-oligosaccharides.
- Tanaka, Tomonari,Huang, Wei Chun,Noguchi, Masato,Kobayashi, Atsushi,Shoda, Shin-ichiro
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supporting information; experimental part
p. 2154 - 2157
(2009/08/17)
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- Thermochemical transformation of glucose to 1,6-anhydroglucose in high-temperature steam
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An aqueous solution of glucose was reacted at temperatures from 200 to 400 °C under atmospheric pressure using a continuous flow reactor. For reaction temperatures above 300 °C, the liquid product yield was not sensitive to the temperature change; on the other hand, below 300 °C, it decreased rapidly with decreasing temperature. 1,6-Anhydro-β-d-glucopyranose (AGP) and 1,6-anhydro-β-d-glucofuranose (AGF) were the major components in the liquid product. The yields of AGP and AGF were 40% and 19%, respectively, at 360 °C and a feed rate of 0.5 mL/min. The optimum space time to produce AGP and AGF was about 0.2-0.4 s under the present temperature conditions.
- Sasaki, Masahide,Takahashi, Kenji,Haneda, Yui,Satoh, Hiroe,Sasaki, Akiyoshi,Narumi, Atsushi,Satoh, Toshifumi,Kakuchi, Toyoji,Kaga, Harumi
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p. 848 - 854
(2008/09/16)
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- A kinetic model for production of glucose by hydrolysis of levoglucosan and cellobiosan from pyrolysis oil
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Anhydro sugars, produced during wood pyrolysis, can by hydrolyzed to sugars under acidic conditions. The acid hydrolysis of two common anhydro sugars in wood pyrolysis oils, levoglucosan (1,6-anhydro-β-d-glucopyranose) and cellobiosan (β-d-glucopyranosyl-(1→4)-1,6-anhydro-d-glucopyranose), was investigated. Levoglucosan hydrolysis to glucose follows a first-order reaction, with an activation energy of 114 kJ mol-1. For cellobiosan hydrolysis, 44% of the cellobiosan is hydrolyzed initially via the β-(1→4) glycosidic bond to form levoglucosan and glucose. The remaining cellobiosan is hydrolyzed initially at the 1,6 anhydro bond to form cellobiose. Both reactions are first order with respect to cellobiosan, with an activation energy of 99 kJ mol-1. The intermediate levoglucosan and cellobiose are hydrolyzed to glucose.
- Helle, Steve,Bennett, Nicole M.,Lau, Karen,Matsui, Justin H.,Duff, Sheldon J.B.
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p. 2365 - 2370
(2008/02/12)
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- Glucose reactions within the heating period and the effect of heating rate on the reactions in hot compressed water
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Glucose reactions were conducted in hot compressed water (473-773 K, 4-40 MPa) by means of a batch-type reactor. The reactions in the heating period (about for 60 s) were observed. More than 80% of the glucose was consumed in the heating period above 573 K. Gasification of glucose was promoted with increasing temperature. The effect of heating rate (from 4.2 to 15.8 K/s) on glucose conversion was also examined, and gasification of glucose was enhanced with increasing the heating rate.
- Watanabe, Masaru,Aizawa, Yuichi,Iida, Toru,Levy, Caroline,Aida, Taku M.,Inomata, Hiroshi
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p. 1931 - 1939
(2007/10/03)
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- Glucose reactions with acid and base catalysts in hot compressed water at 473 K
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The effects of the homogeneous catalysts (H2SO4 and NaOH) and heterogeneous catalysts (TiO2 and ZrO2) on glucose reactions were examined in hot compressed water (473 K) by a batch-type reactor. From the homogeneous catalyst studies, we confirmed that the acid catalyst promoted dehydration, while isomerization of glucose to fructose was catalyzed by alkali. Anatase TiO2 was found to act as an acid catalyst to promote formation of 5-hydroxymethylfuraldehyde (HMF). Zirconia (ZrO2) was a base catalyst to promote the isomerization of glucose. The effects of the additives were also confirmed through fructose reactions.
- Watanabe, Masaru,Aizawa, Yuichi,Iida, Toru,Aida, Taku M.,Levy, Caroline,Sue, Kiwamu,Inomata, Hiroshi
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p. 1925 - 1930
(2007/10/03)
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- Methoxyphenols from burning of Scandinavian forest plant materials
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Semivolatile compounds in smoke from gram-scale incomplete burning of plant materials were assessed by gas chromatography and mass spectrometry. Gas syringe sampling was shown to be adequate by comparison with adsorbent sampling. Methoxyphenols as well as 1,6-anhydroglucose were released in amounts as large as 10 mg kg-1 of dry biomass at 90% combustion efficiency. Wood, twigs, bark and needles from the conifers Norway spruce and Scots pine emitted 12 reported 2-methoxyphenols in similar proportions. Grass, heather and birchwood released the same 2-methoxyphenols but also the corresponding 2,6-dimethoxyphenols which are characteristic of angiosperms. The methoxyphenols are formed from lignin and differ in structure by the group in para position relative to the phenolic OH group. Prominent phenols were those with trans-l-propenyl and ethenyl groups in that position. Vanillin, 4- hydroxy-3-methoxybenzaldehyde, was a prominent carbonyl compound from the conifer materials. (C) 2000 Elsevier Science Ltd.
- Kjaellstrand, Jennica,Ramnaes, Olle,Petersson, Goeran
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p. 735 - 741
(2007/10/03)
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- Polymer pyrolysis and oxidation studies in a continuous feed and flow reactor: Cellulose and polystyrene
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A dual-zone, continuous feed tubular reactor is developed to assess the potential for formation of products from incomplete combustion in thermal oxidation of common polymers. Solid polymer (cellulose or polystyrene) is fed continuously into a volatilization oven where it fragments and vaporizes. The gas-phase polymer fragments flow directly into a second, main flow reactor to undergo further reaction. Temperatures in the main flow reactor are varied independently to observe conditions needed to convert the initial polymer fragments to CO2 and H2O. Combustion products are monitored at main reactor temperatures from 400 to 850 °C and at 2.0-s total residence time with four on-line GC/FIDs; polymer reaction products and intermediates are further identified by GC/MS analysis. Analysis of polymer decomposition fragments at 400 °C encompasses complex oxygenated and aromatic hydrocarbon species, which range from high-molecular-weight intermediates of ca. 300 amu, through intermediate mass ranges down to C1 and C2 hydrocarbons, CO, and CO2. Approximately 41 of these species are positively identified for cellulose and 52 for polystyrene. Products from thermal oxidation of cellulose and polystyrene are shown to achieve complete combustion to CO2 and H2O at a main reactor temperature of 850 °C under fuel-lean equivalence ratio and 2.0-s reaction time. A dual-zone, continuous feed tubular reactor is developed to assess the potential for formation of products from incomplete combustion in thermal oxidation of common polymers. Solid polymer (cellulose or polystyrene) is fed continuously into a volatilization oven where it fragments and vaporizes. The gas-phase polymer fragments flow directly into a second, main flow reactor to undergo further reaction. Temperatures in the main flow reactor are varied independently to observe conditions needed to convert the initial polymer fragments to CO2 and H2O. Combustion products are monitored at main reactor temperatures from 400 to 850°C and at 2.0-s total residence time with four on-line GC/FIDs; polymer reaction products and intermediates are further identified by GC/MS analysis. Analysis of polymer decomposition fragments at 400°C encompasses complex oxygenated and aromatic hydrocarbon species, which range from high-molecular-weight intermediates of ca. 300 amu, through intermediate mass ranges down to C1 and C2 hydrocarbons, CO, and CO2. Approximately 41 of these species are positively identified for cellulose and 52 for polystyrene. Products from thermal oxidation of cellulose and polystyrene are shown to achieve complete combustion to CO2 and H2O at a main reactor temperature of 850°C under fuel-lean equivalence ratio and 2.0-s reaction time.
- Park, Byung-Ik,Bozzelli, Joseph W.,Booty, Michael R.,Bernhard, Mary J.,Mesuere, Karel,Pettigrew, Charles A.,Shi, Ji-Chun,Simonich, Staci L.
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p. 2584 - 2592
(2007/10/03)
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- On the regioselective acylation of 1,6-anhydro-β-D- and L-hexopyranoses catalysed by lipases: Structural bass and synthetic applications
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With the aim of providing new methods for the regioselective protection at the 2,3 and 4 positions of monosaccharides, we have studied the acetylation of a class of rigid sugars: the 1,6-anhydro-β-D- and L-hexopyranoses (hexopyranosanes D-1 to D-5 and L-1 to L-5), using vinyl acetate as an acyl donor and two common lipases,Candida rugosa and Pseudomonas cepacia, as catalysts. Our results indicate that the relative orientation of the hydroxyls governs the regioselectivity of acetylation. In the D-series, when the 3-OH is in the axial position, acetylation occurs mainly at the 4-axial OH, while the 2-axial OH is preferred when the 4-OH is equatorial. Conversely, when the 3-OH is equatorial, a strong selectivity affects the equatorial 2-OH. Compounds of the L-series were shown to be poor substrates for the lipase Pseudomonas cepacia except for L-galactosane for which the 2-monoacetyl ester was obtained in good yield. An attempt to rationalize the results by means of molecular modelling is also made to account for the catalytic activity of the Candida rugosa lipase on hexopyranosanes 1-3.
- Boissière-Junot, Nathalie,Tellier, Charles,Rabiller, Claude
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- Enolic ortho esters. VI* A new 'pyranose → cyclohexane' transformation via 1,6-dideoxy-1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-xylo-hex-5-enopyranose
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Hydrolysis of methyl 6-chloro-6-deoxy-2,3,4-tri-O-methyl-α-D-glucopyranoside (19b) and Swern oxidation of the resulting anomeric hemiacetals (20) gave 6-chloro-6-deoxy-2,3,4-tri-O-methyl-D-glucono-1,5-lactone (21), treatment of which with 1,2-bis(trimethylsilyloxy)ethane in the presence of trimethylsilyl trifluoromethanesulfonate gave 6-chloro-1,6-dideoxy-1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-glucopyranose (23a). Conversion of (23a) into the corresponding 6-iodo compound (23b) and treatment of this with 1,8-diazabicyclo[5.4.0]undec-7-ene afforded the enolic ortho ester 1,6-dideoxy-1,1-ethylenedioxy-2,3,4-triO-methyl-D-xylo-hex-5-enopyranose (26). Reaction of (26) with methylmagnesium iodide, or with titanium tetrachloride, gave (1R,6S,7R,8R,9S)-7,8,9-trimethoxy-6-methyl-2,5-dioxabicyclo[4.3.1]decan-1-ol (34), or (2S,3R,4R)-5,5-ethylenedioxy-2,3,4-trimethoxycyclohexanone (28), respectively.
- Bourke, David G.,Collins, David J.,Hibberd, Angus I.,McLeod, Malcolm D.
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p. 425 - 434
(2007/10/03)
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- Process for the production of anhydrosugars from lignin and cellulose containing biomass by pyrolysis
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A process is described for the production of anhydrosugars such as levoglucosan (1,6-anhydro-β-D-glucopyranose), from liquids obtained by the fast thermal pyrolysis of pretreated lignocellulosics or celluloses. In this process, the pyrolytic liquids containing the anhydrosugars are produced with a substantially reduced amount of lignin-derived components by using as feedstock materials which have been previously delignified and then pretreated, or by preferential oxidation of the lignin fraction of a pretreated biomass during pyrolysis. The preparation from pretreated biomass of pyrolytic liquors from which the lignin derived chemical products of fast pyrolysis are absent or in low concentrations permits simpler and more economical recovery of crystalline levoglucosan and other anhydrosugars, or a more economical preparation of readily fermentable aqueous sugar solutions therefrom. A new procedure for the recovery of crystalline levoglucosan from such solutions is described.
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