- Bio-based Surfactants
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Bio-based surfactants have great opportunity for use in a variety of applications such as laundry detergents, industrial cleaners, adjuvants, and oil and gas. Surfactants in these applications can be nonionic, anionic, cationic, or amphoteric. Utilizing high oleic soybean oil as a platform chemical, a variety of surfactants and properties can be produced. While early work focused solely on surfactant use in laundry cleaning and fracking, recent work has expanded functional groups and application evaluations in hard surface cleaning. The current invention expands on Battelle's high oleic soybean oil (HOSO) surfactant technology. Use of HOSO overcomes the limitations of regular soybean oil and significantly reduces or eliminates undesirable byproducts in most chemistries. However, with use of select reagents, a few candidates were achievable with regular epoxidized soybean oil (ESO). The HOSO surfactant platform offers several key advantages including: a highly water miscible (not typical of C18 surfactants) and water stable surfactant; ability to adjust and vary hydrophilic-lipophilic (HLB) values for stain removal performance; and increased biodegradability without toxic or persistent by-products.
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- Ethanolysis of selected catalysis by functionalized acidic ionic liquids: An unexpected effect of ILs structural functionalization on selectivity phenomena
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A series of functionalized hydrogen sulfate imidazolium ILs were synthesized and applied as catalysts in the reaction of glucose, xylose and fructose with ethanol. In this research, an unexpected selectivity phenomenon was observed. It showed that in this reaction functionalized ILs should be considered as a special type of catalyst. Functionalization of alkyl imidazolium ILs, especially the addition of electronegative OH groups, causes a clear and unexpected effect manifested via visible changes in the selectivity of the reaction studied. In the case of fructose, an increase in the number of OH groups affects an increase in the selectivity towards ethyl levulinate from 14.2% for [bmim]HSO4 to 20.1% for [glymim]HSO4 with an additional increase in selectivity to 5-hydroxymethyfurfural. In turn, for xylose, the introduction of OH groups to the alkyl chain was manifested by a decrease in selectivity to furfural as its ethyl acetal and an increase in selectivity to ethylxylosides. This journal is
- Nowakowska-Bogdan, Ewa,Nowicki, Janusz
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p. 1857 - 1866
(2022/02/05)
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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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- Synthesis of alkyl α- and β-d-glucopyranoside-based chiral crown ethers and their application as enantioselective phase-transfer catalysts
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Chiral monoaza-15-crown-5-type lariat ethers annelated to alkyl 4,6-O-benzylidene-α- and β-d-glucopyranosides have been synthesized. These macrocycles generated significant asymmetric induction as phase-transfer catalysts in a few two-phase reactions. The catalytic effect of the lariat ethers with methoxy, ethoxy, and i-propoxy substituents on C-1 of the sugar unit in both α and β positions was compared. In liquid–liquid two-phase reactions, the nature and position of the substituents did not have much effect. The α-anomers were somewhat more efficient in terms of enantioselectivity than the β forms. In asymmetric Darzens condensations, in the epoxidation of trans-chalcone, in the Michael addition of β-nitrostyrene and diethyl acetamidomalonate, and in the reaction of 2-benzylidene-1,3-indandione with diethyl bromomalonate, maximum enantioselectivities of 73, 94, 78, and 72%, respectively, were obtained in presence of glucopyranoside-based lariat ethers as catalysts.
- Pálv?lgyi, ádám,Rapi, Zsolt,Ozohanics, Olivér,Tóth, Gábor,Keglevich, Gy?rgy,Bakó, Péter
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p. 1627 - 1645
(2017/11/16)
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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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supporting information
p. 76 - 79
(2018/01/17)
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- Design of Ordered Mesoporous Sulfonic Acid Functionalized ZrO2/organosilica Bifunctional Catalysts for Direct Catalytic Conversion of Glucose to Ethyl Levulinate
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Ordered mesoporous sulfonic acid functionalized ZrO2/organosilica catalysts (SO42?/ZrO2-PMO-SO3H) bearing tunable Br?nsted, and Lewis acid site distributions were prepared by a P123-directed sol-gel co-condensation route followed by ClSO3H functionalization. As-prepared catalysts were applied in the conversion of glucose to ethyl levulinate in ethanol medium. The SO42?/ZrO2-PMO-SO3H-catalyzed target reaction followed a glucose-ethyl glucoside-ethyl fructoside-5-ethoxymethylfurfural-ethyl levulinate pathway dominated by the synergistic effect of the super strong Br?nsted acidity, and moderate Lewis acidity of the catalysts. Additionally, by combining the advantages of the considerably high Br?nsted (696 μeq g?1), Lewis acid site density (703 μeq g?1), optimal Br?nsted/Lewis molar ratio (0.99), and excellent porosity properties, the SO42?/ZrO2-PMO-SO3H1.0 obtained at an initial Si/Zr molar ratio of 1.0 exhibited the highest ethyl levulinate yield (42.3 %) among the various tested catalysts. Moreover, the SO42?/ZrO2-PMO-SO3H can be reused three times without obvious changes in activity, morphology, and chemical structure.
- Song, Daiyu,Zhang, Qingqing,Sun, Yingnan,Zhang, Panpan,Guo, Yi-Hang,Hu, Jiang-Lei
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p. 4967 - 4979
(2018/10/02)
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- Supported Tetrahedral Oxo-Sn Catalyst: Single Site, Two Modes of Catalysis
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Mild calcination in ozone of a (POSS)-Sn-(POSS) complex grafted on silica generated a heterogenized catalyst that mostly retained the tetrahedral coordination of its homogeneous precursor, as evidenced by spectroscopic characterizations using EXAFS, NMR, UV-vis, and DRIFT. The Sn centers are accessible and uniform and can be quantified by stoichiometric pyridine poisoning. This Sn-catalyst is active in hydride transfer reactions as a typical solid Lewis acid. However, the Sn centers can also create Br?nsted acidity with alcohol by binding the alcohol strongly as alkoxide and transferring the hydroxyl H to the neighboring Sn-O-Si bond. The resulting acidic silanol is active in epoxide ring opening and acetalization reactions.
- Beletskiy, Evgeny V.,Hou, Xianliang,Shen, Zhongliang,Gallagher, James R.,Miller, Jeffrey T.,Wu, Yuyang,Li, Tiehu,Kung, Mayfair C.,Kung, Harold H.
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supporting information
p. 4294 - 4297
(2016/05/09)
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- Direct catalytic transformation of biomass derivatives into biofuel component γ-valerolactone with magnetic nickel-zirconium nanoparticles
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A series of mixed oxide nanoparticles were prepared by a coprecipitation method and characterized by many techniques. Nickel-zirconium oxide catalysts and their partially reduced magnetic counterparts were highly efficient in the direct transformation of biomass derivatives, including ethyl levulinate, fructose, glucose, cellobiose, and carboxymethyl cellulose, into γ-valerolactone (GVL) without the use of an external hydrogen source, producing a maximum GVL yield of 95.2 % at 200 °C for 3 h with hydrogen-reduced magnetic Zr5Ni5 nanoparticles (-1 h-1). Moreover, the magnetic Zr5Ni5 nanoparticles were conveniently recovered by means of a magnet for five cycles with almost constant activity. Attractive separation: Acid-base bifunctional NiZr nanocatalysts with strong magnetism show high activity and reusability in the transformation of biomass derivatives, including EL, fructose, glucose, cellobiose, and carboxymethyl cellulose, into γ-valerolactone (GVL) with 95.2 % yield and 98 % selectivity (see figure).
- Li, Hu,Fang, Zhen,Yang, Song
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p. 135 - 142
(2016/02/05)
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- Metal-catalyzed stereoselective and protecting-group-free synthesis of 1,2-cis-glycosides using 4,6-dimethoxy-1,3,5-triazin-2-yl glycosides as glycosyl donors
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4,6-Dimethoxy-1,3,5-triazin-2-yl glycosides, glycosyl donors prepared in one step from free saccharides without protection of the hydroxy groups, were stereoselectively and equivalently converted to the corresponding 1,2-cis-glycosides by using a catalytic amount of metal catalyst. This reaction was successfully applied not only to monosaccharides, but also to di- and oligosaccharides.
- Tanaka, Tomonari,Kikuta, Naoya,Kimura, Yoshiharu,Shoda, Shin-Ichiro
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supporting information
p. 846 - 848
(2015/06/22)
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- Solvent and α-secondary kinetic isotope effects on β-glucosidase
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β-Glucosidase from sweet almond is a retaining, family 1, glycohydrolase. It is known that glycosylation of the enzyme by aryl glucosides occurs with little, if any, acid catalysis. For this reaction both the solvent and α-secondary kinetic isotope effects are 1.0. However, for the deglucosylation reaction (e.g., kcat for 2,4-dinitrophenyl-β-D-glucopyranoside) there is a small solvent deuterium isotope effect of 1.50 (± 0.06) and an α-secondary kinetic isotope effect of 1.12 (± 0.03). For aryl glucosides, kcat/KM is very sensitive to the pKa of the phenol leaving group [βlg - 1; Dale et al., Biochemistry 25 (1986) 2522-2529]. With alkyl glucosides the βlg is smaller (between - 0.2 and - 0.3) but still negative. This, coupled with the small solvent isotope effect on the pH-independent second-order rate constant for the glucosylation of the enzyme with 2,2,2-trifluoroethyl-β-glucoside [D2O(kcat/KM) = 1.23 (± 0.04)] suggests that there is more glycone-aglycone bond fission than aglycone oxygen protonation in the transition state for alkyl glycoside hydrolysis. The kinetics constants for the partitioning (between water and various alcohols) of the glucosyl-enzyme intermediate, coupled with the rate constants for the forward (hydrolysis) reaction provide an estimate of the stability of the glucosyl-enzyme intermediate. This is a relatively stable species with an energy about 2 to 4 kcal/mol higher than that of the ES complex. This article is part of a Special Issue entitled: Enzyme Transition States from Theory and Experiment.
- Xie, Miaomiao,Byers, Larry D.
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p. 1776 - 1781
(2015/03/30)
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- METHOD OF PREPARING FURFURAL COMPOUNDS
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Provided is a two-step method of producing a compound of chemical formula 1 in the presence of an alcohol solvent and a Group 3B metal catalyst or a salt thereof, comprising a first step comprising alkylation or isomerization of an aldohexose-containing substrate to obtain an intermediate, and a second step comprising dehydration of the intermediate to produce a compound of chemical formula 1. Preferably, additional solvent and/or catalyst are not added in the second step.
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Paragraph 0064
(2014/05/20)
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- One-pot conversion of carbohydrates into 5-ethoxymethylfurfural and ethyl d-glucopyranoside in ethanol catalyzed by a silica supported sulfonic acid catalyst
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In this study, prepared silica supported sulfonic acid was used as a heterogeneous catalyst for the production of 5-ethoxymethylfurfural (EMF) from fructose based carbohydrates and the synthesis of ethyl d-glucopyranoside from glucose based carbohydrates in ethanol. EMF was obtained in a high yield of 83.8% from 5-hydroxymethylfurfural (HMF) after 10 h, and a 63.1% yield was obtained from fructose at 100°C for 24 h. Temperature experiments demonstrated that a higher reaction temperature (in the case of 120°C) resulted in side reactions such as polymerization of HMF and alcoholysis of HMF into ethyl levulinates. When di- and poly-saccharides (sucrose and inulin) were used, the fructose moieties in sucrose and inulin were also successfully converted into EMF. However, the silica supported sulfonic acid catalyst was inert for the production of EMF from aldose based carbohydrates such as glucose and cellobiose. Ethyl d-glucopyranoside was formed in a high yield of 91.7% from glucose. More importantly, the catalyst could be reused several times without losing its catalytic activity with an average EMF yield of around 60% from a one-pot reaction of fructose. This work provides a good outlook for the conversion of carbohydrates into fine chemicals and biofuel additive. The Royal Society of Chemistry 2013.
- Liu, Bing,Zhang, Zehui
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p. 12313 - 12319
(2013/09/02)
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- Protection-free synthesis of alkyl glycosides under hydrogenolytic conditions
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A convenient protection-free synthetic route for the preparation of alkyl glycosides has been developed. The alcoholysis of one-step preparable glycosyl donors, 4,6-dibenzyloxy-1,3,5-triazin-2-yl (DBT) glycosides, under hydrogenolytic conditions gave the corresponding glycosides in good yields without the addition of any acid promoters. The method could be successfully applied to the glycosylation of an acidlabile oligosaccharide.
- Ishihara, Masaki,Takagi, Yuka,Li, Gefei,Noguchi, Masato,Shoda, Shin-Ichiro
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supporting information
p. 1235 - 1237
(2013/10/22)
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- Purification, characterization, and gene identification of an α-glucosyl transfer enzyme, a novel type α-glucosidase from Xanthomonas campestris WU-9701
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The α-glucosyl transfer enzyme (XgtA), a novel type α-glucosidase produced by Xanthomonas campestris WU-9701, was purified from the cell-free extract and characterized. The molecular weight of XgtA is estimated to be 57 kDa by SDS-PAGE and 60 kDa by gel filtration, indicating that XgtA is a monomeric enzyme. Kinetic properties of XgtA were determined for α-glucosyl transfer and maltose-hydrolyzing activities using maltose as the α-glucosyl donor, and if necessary, hydroquinone as the acceptor. The Vmax value for α-glucosyl transfer activity was 1.3 × 10-2 (mM/s); this value was 3.9-fold as much as that for maltose-hydrolyzing activity. XgtA neither produced maltooligosaccharides nor hydrolyzed sucrose. The gene encoding XgtA that contained a 1614-bp open reading frame was cloned, identified, and highly expressed in Escherichia coli JM109 as the host. Site-directed mutagenesis identified Asp201, Glu270, and Asp331 as the catalytic sites of XgtA, indicating that XgtA belongs to the glycoside hydrolase family 13.
- Sato, Toshiyuki,Hasegawa, Nobukazu,Saito, Jun,Umezawa, Satoru,Honda, Yuki,Kino, Kuniki,Kirimura, Kohtaro
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body text
p. 20 - 27
(2012/09/05)
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- Isolation and characterization of a novel α-glucosidase with transglycosylation activity from Arthrobacter sp. DL001
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A strain of Arthrobacter sp. DL001 with high transglycosylation activity was successfully isolated from the Yellow Sea of China. To purify the extracellular enzyme responsible for transglycosylation, a four-step protocol was adopted and the enzyme with electrophoretical purity was obtained. The purified enzyme has a molecular mass of 210 kDa and displays a narrow hydrolysis specificity towards α-1,4-glucosidic bond. Its hydrolytic activity was identified as decreasing in the order of maltotriose > panose > maltose. Only 3.61% maltose activity occurs when p-nitrophenyl α-d-glycopyranoside serves as a substrate, suggesting that this enzyme belongs to the type II α-glucosidase. In addition, the enzyme was able to transfer glucosyl groups from the donors containing α-1,4-glucosidic bond specific to glucosides, xylosides and alkyl alcohols in α-1,4- or α-1,6-manners. A decreased order of activity was observed when maltose, maltotriose, panose, β-cyclodextrin and soluble starch served as glycosyl donors, respectively. When maltose was utilized as a donor and a series of p-nitrophenyl-glycosides as acceptors, the glucosidase was capable of transferring glucosyl groups to p-nitrophenyl-glucosides and p-nitrophenyl-xylosides in α-1,4- or α-1,6-manners. The yields of p-nitrophenyl-oligosaccharides could reach 42-60% in 2 h. When a series of alkyl alcohols were utilized as acceptors, the enzyme exhibited its transglycosylation activities not only to the primary alcohols but also to the secondary alcohols with carbon chain length 1-4. Therefore, all the results indicated that the purified α-glucosidase present a useful tool for the biosynthesis of oligosaccharides and alkyl glucosides.
- Zhou, Kun,Luan, Hong-Wei,Hu, Ying,Ge, Guang-Bo,Liu, Xing-Bao,Ma, Xiao-Chi,Hou, Jie,Wang, Xiu-Li,Yang, Ling
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experimental part
p. 48 - 57
(2012/09/07)
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- Significantly improved equilibrium yield of long-chain alkyl glucosides via reverse hydrolysis in a water-poor system using cross-linked almond meal as a cheap and robust biocatalyst
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An array of ten β-D-glucopyranosides with varied alkyl chain lengths were enzymatically synthesized. It was found that for longer alkyl chains a lower initial rate and final yield of glucoside was obtained except for methyl glucoside because of the severe toxicity of methanol to the enzyme. From a thermodynamics point of view, the equilibrium constant and Gibbs free energy variation of the glucoside syntheses were systematically investigated. To improve the final yields of the glucosides containing long alkyl chains the equilibrium of the enzymatic glucoside synthesis was altered. The equilibrium yield of decyl β-D-glucoside increased from 1.9 to 6.1 when the water content was reduced from 10 to 5 (v/v) using tert-butanol as a cosolvent and 0.10 mol/L of glucose as a substrate. As for the other longer alkyl chain glucosides, heptyl β-D-glucoside was found to have significant surface activity as well.
- Wang, Qinqqin,Yu, Huilei,Zhao, Na,Li, Chunxiu,Shang, Yazhuo,Liu, Honglai,Xu, Jianhe
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p. 275 - 280
(2012/06/29)
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- Significantly Improved Equilibrium Yield of Long-Chain Alkyl Glucosides via Reverse Hydrolysis in a Water-Poor System Using Cross-Linked Almond Meal as a Cheap and Robust Biocatalyst
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An array of ten β-D-glucopyranosides with varied alkyl chain lengths were enzymatically synthesized. It was found that for longer alkyl chains a lower initial rate and final yield of glucoside was obtained except for methyl glucoside because of the severe toxicity of methanol to the enzyme. From a thermodynamics point of view, the equilibrium constant and Gibbs free energy variation of the glucoside syntheses were systematically investigated. To improve the final yields of the glucosides containing long alkyl chains the equilibrium of the enzymatic glucoside synthesis was altered. The equilibrium yield of decyl β-D-glucoside increased from 1.9% to 6.1% when the water content was reduced from 10% to 5% (v/v) using tert-butanol as a cosolvent and 0.10 mol/L of glucose as a substrate. As for the other longer alkyl chain glucosides, heptyl β-D-glucoside was found to have significant surface activity as well.
- Wang, Qinqqin,Yu, Huilei,Zhao, Na,Li, Chunxiu,Shang, Yazhuo,Liu, Honglai,Xu, Jianhe
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p. 275 - 280
(2016/04/10)
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- Conversion of mono- and disaccharides to ethyl levulinate and ethyl pyranoside with sulfonic acid-functionalized ionic liquids
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Value-added chemicals from sugars: Sulfonic acid-functionalized ionic liquids are attractive and promising catalyst for the conversion of sugars to ethyl levulinate and ethyl-D-glucopyranoside in ethanol. These task-specific ionic liquids can be recovered and reused in at least three cycles in the conversion of fructose to ethyl levulinate without any loss of activity. Copyright
- Saravanamurugan, Shunmugavel,Buu, Olivier Nguyen Van,Riisager, Anders
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experimental part
p. 723 - 726
(2012/05/19)
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- Levulinic esters from the acid-catalysed reactions of sugars and alcohols as part of a bio-refinery
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Polymeric humin formation greatly diminishes levulinic acid yields in acid treatment of C6 sugars in aqueous medium. Protecting reactive functional groups of sugars and reaction intermediates via acetalisation and etherification in methanol medium effectively suppresses humin formation and remarkably enhances the production of levulinic esters.
- Hu, Xun,Li, Chun-Zhu
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supporting information; body text
p. 1676 - 1679
(2011/09/12)
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- Substrate specificity in hydrolysis and transglucosylation by family 1 β-glucosidases from cassava and Thai rosewood
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Thai rosewood (Dalbergia cochinchinensis Pierre) dalcochinase and cassava (Manihot esculenta Crantz) linamarase are glycoside hydrolase family 1 β-glucosidases with 47% amino acid sequence identity. Each enzyme can hydrolyze its natural substrate, dalcochinin-8′-O-β-d-glucoside and linamarin, respectively, but not the natural substrate of the other enzyme. Linamarase can transfer glucose to primary, secondary and tertiary alcohols with high efficiency, while dalcochinase can transglucosylate primary and secondary alcohols at moderate levels. In this study, eight amino acid residues in the aglycone binding pocket of dalcochinase were individually replaced with the corresponding residues of linamarase, in order to identify residues that may account for their catalytic differences. The residues I185 and V255 of dalcochinase appeared important for its substrate specificity, with their respective mutations resulting in 24- and 12-fold reductions in k cat/Km for the hydrolysis of dalcochinin-8′-O- β-d-glucoside. Transglucosylation activity was improved when I185, N189 and V255 of dalcochinase were replaced with A201, F205 and F271 of linamarase, respectively, suggesting these residues support transglucosylation in linamarase. Among these three mutants, only the N189F mutant showed significant increases in the rate constants for the reactivation of trapped glucosyl-enzyme intermediates by all alcohols. Together, our results suggest that both hydrophobicity and geometry are important determinants for substrate specificity in hydrolysis and transglucosylation by these family 1 β-glucosidases.
- Kongsaeree, Prachumporn T.,Ratananikom, Khakhanang,Choengpanya, Khuanjarat,Tongtubtim, Nusra,Sujiwattanarat, Penporn,Porncharoennop, Chompoonuth,Onpium, Amornrat,Svasti, Jisnuson
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experimental part
p. 257 - 265
(2011/02/22)
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- POLYMER STABILIZER
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A polymer stabilizer comprising the following alkoxy compound: the alkoxy compound: a compound obtained by alkoxylating at least one hydroxyl group contained in a compound of the following formula (1) containing one formyl group or carbonyl group and (n?1) hydroxyl groups in the molecule with an alkyl group having 1 to 12 carbon atoms: [in-line-formulae]CnH2nOn??(1)[/in-line-formulae] (wherein, n represents an integer of 3 or more).
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- Montmorillonite K-10 as a reusable catalyst for fischer type of glycosylation under microwave irradiation
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Montmorillonite K-10-catalyzed Fischer type glycosylation was studied for various monosacharides with different alcohols under microwave irradiation. The method was found to be efficient, economic, simple, and time saving and the catalyst montmorillonite K-10 was reused three times without loss of catalytic activity and anomeric selectivity. With glycerol, the method gave products glycosylated at primary alcohols only.
- Bordoloi, Manobjyoti
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p. 300 - 308
(2008/12/21)
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- A new method of synthesis of alkyl β-glycosides using sucrose as sugar donor
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Cellobiose phosphorylase from Clostridium thermocellum catalyzed the β-anomer-selective synthesis of alkyl glucosides from cellobiose. Synthesis of alkyl β-glucoside from inexpensive sucrose using cellobiose phosphorylase and sucrose phosphorylase from Pseudomonas saccharophilia was investigated. By combined use of these two phosphorylases, alkyl β-glucoside was anomer-selectively synthesized from sucrose and alkyl alcohol.
- Kino, Kuniki,Satake, Ryoko,Morimatsu, Takayuki,Kuratsu, Shoko,Shimizu, Yu,Sato, Masaru,Kirimura, Kohtaro
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p. 2415 - 2417
(2008/12/23)
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- Synthesis of n-alkyl glucosides by amyloglucosidase
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Amyloglucosidase from Rhizopus mold (3.2.1.3) has been employed for the synthesis of n-alkyl glucosides from alcohols of carbon chain lengths Cl to C18 by both shake flask and reflux methods. Glucoside yields obtained from the reflux method (5-44%) are better than those from the shake flask method (3-28%). While the shake flask method favoured glucosylation of medium chain length alcohols, the reflux method at pH 5.0, favoured glucosylation of all the chain lengths. n-Octyl-D-glucoside, n-octyl-maltoside and n-octyl-sucroside are also synthesized and optimum conditions for the synthesis of n-octyl-D-glucoside at both shake flask and reflux methods have been worked out.
- Vijayakumar, Giriyapura R.,George, Charles,Divakar, Soundar
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p. 314 - 319
(2008/02/09)
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- Fast analysis of sugars, fruit acids, and vitamin C in sea buckthorn (Hippophae rhamnoides L.) varieties
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A fast, one-step gas chromatographic method was developed to analyze trimethylsilyl (TMS) derivatives of sugars, fruit acids, and ascorbic acid in sea buckthorn (Hippohae rhamnoides L.) berries. The method was applied to berry press juice of sea buckthorn of different origins grown in Finland during the 2003 and 2004 seasons. The method gave reliable results for D-fructose, D-glucose, ethyl-D-glucose, and malic, quinic, and ascorbic acids, which are the major sugars and acids in sea buckthorn juice. For the first time in sea buckthorn and evidently in any berry, the presence of ethyl β-D-glucopyranoside is reported. The structure of ethyl glucose was verified by high-performance liquid chromatography (HPLC), gas chromatography (GC), MS, and NMR analyses of both the isolated and the synthesized compounds. In the GC method, vitamin C was analyzed as ascorbic acid only, and dehydroascorbic acid was thus not taken into account.
- Tiitinen, Katja M.,Yang, Baoru,Haraldsson, Gudmundur G.,Jonsdottir, Sigridur,Kallio, Heikki P.
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p. 2508 - 2513
(2007/10/03)
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- Pharmacological activity and?hydrolysis behavior of?novel ibuprofen glucopyranoside conjugates
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Novel ester prodrugs (II, III and IV) of ibuprofen (I) were synthesized using α-methyl, ethyl and propyl glucopyranoside as promoieties and tested for their anti-inflammatory, analgesic and ulcerogenic activities. Study of their chemical hydrolysis in aqueous buffer (pH 3.0-10.0) showed that these compounds acted as true prodrugs of ibuprofen, giving the ibuprofen and alkyl glucopyranoside. Additionally, all the derivatives studied did cleave rapidly inside the biological system and on oral administration did elicit a pharmacological profile quite similar to that of ibuprofen, but, unlike this drug, they displayed reduced gastric ulceration. In conclusion, these alkyl glucopyranoside esters have promising properties as prodrugs for oral delivery of ibuprofen.
- Zhao, Xiangguo,Tao, Xinyi,Wei, Dongzhi,Song, Qingxun
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p. 1352 - 1358
(2007/10/03)
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- Process for preparing alkylglycosides
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The invention relates to a process for preparing alkylpolyglycosides from monomeric glycosides, oligo- or polyglycosides and alcohols according to the general scheme [in-line-formulae](Glyc-O)zH+R1—OH→(Glyc-O)z′R1 [/in-line-formulae] where z≧1 z′≦z, preferably from 1 to 10, (Glyc-O)— is a glycoside radical, R1 is a hydrocarbon radical which optionally contains multiple bonds and/or heteroatoms, which comprises carrying out the reaction under supercritical conditions with regard to the alcohol, preferably at pressures and temperatures which are at least 5% above the critical parameters, the alcohols serving both as the solvent and as reactants.
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Page/Page column 4
(2008/06/13)
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- Regioselective acylation of carbohydrate derivatives using lipases leading to a facile two-step procedure for the separation of some α- and β-glucopyranosides and galactopyranosides
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The resolution of α- and β-anomers of glucopyranosides and galactopyranosides was achieved via enzyme-catalysed regioselective acylation. This two-step procedure to prepare pure α- and β-anomers of glycopyranosides would be most useful for the cases where glycosidases are not available or expensive to purchase. From a synthetic viewpoint, the regioselective acylation of glycopyranosides provides access to mono- and di-esters with well-defined substitution patterns.
- Gon?alves, Pedro M.L.,Roberts, Stanley M.,Wan, Peter W.H.
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p. 927 - 932
(2007/10/03)
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- Heteroaryl thioglycosides, a new class of substrates for glycosidases
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We have found that heteroaryl thioglycosides are useful substrates of β-glucosidase from almond and can act as a new class of donors in transglycosylation reaction.
- Niemiec-Cyganek,Szeja
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p. 969 - 973
(2007/10/03)
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- Biotransformation of low-molecular-weight alcohols by Coleus forskohlii hairy root cultures
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Coleus forskohlii hairy root cultures were shown to biotransform methanol and ethanol to the corresponding β-D-glucopyranosides and β-D-ribo-hex-3-ulopyranosides, and 2-propanol to its β-D-glucopyranoside.
- Li, Wei,Koike, Kazuo,Asada, Yoshihisa,Yoshikawa, Takafumi,Nikaido, Tamotsu
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p. 729 - 731
(2007/10/03)
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- Purification and characterization of a novel fungal α-glucosidase from Mortierella alliacea with high starch-hydrolytic activity
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The fungal strain Mortierella alliacea YN-15 is an arachidonic acid producer that assimilates soluble starch despite having undetectable α-amylase activity. Here, a α-glucosidase responsible for the starch hydrolysis was purified from the culture broth through four-step column chromatography. Maltose and other oligosaccharides were less preferentially hydrolyzed and were used as a glucosyl donor for transglucosylation by the enzyme, demonstrating distinct substrate specificity as a fungal α-glucosidase. The purified enzyme consisted of two heterosubunits of 61 and 31 kDa that were not linked by a covalent bond but stably aggregated to each other even at a high salt concentration (0.5 M), and behaved like a single 92-kDa component in gel-filtration chromatography. The hydrolytic activity on maltose reached a maximum at 55°C and in a pH range of 5.0-6.0, and in the presence of ethanol, the transglucosylation reaction to form ethyl-α-D-glucoside was optimal at pH 5.0 and a temperature range of 45-50°C.
- Tanaka, Yoshio,Aki, Tsunehiro,Hidaka, Yuki,Furuya, Yuji,Kawamoto, Seiji,Shigeta, Seiko,Ono, Kazuhisa,Suzuki, Osamu
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p. 2415 - 2423
(2007/10/03)
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- Microwave-assisted synthesis of alkyl glycosides
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The reaction of sugars with alcohols and catalytic amounts of an acid in a high frequency field (2.45 GHz) leads to high yields of the corresponding alkyl glycosides. The ratio of the α/β-anomers is influenced by the reaction conditions and reaction controlling.
- Nuechter,Ondruschka,Lautenschlaeger
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p. 1277 - 1283
(2007/10/03)
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- Enzymatic polymerization of poly(ε-CL) containing an ethyl glucopyranoside head group: An NMR study
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The usefulness of the 2D-NMR techniques in the structure determination of the oligo ε-caprolactone ethyl glucopyranoside (oligo(ε-CL) EGP) conjugate, synthesized by a lipase-catalyzed regioselective reaction, is described. Data from a 13C-13C COSY NMR spectrum of the ethyl glucopyranoside is used for complete and unambiguous assignments of the carbon resonances in the 13C NMR spectrum of the anomeric mixture of EGP. A comparison of the DEPT-135 spectrum of the product oligo(ε-CL) EGP conjugate with that of the starting material, ethyl glucopyranoside (EGP), led to the conclusion that the lipase-catalyzed ring-opening of ε-CL initiated by a multifunctional initiator, EGP, proceeded in a regioselective fashion. Also, a detailed analysis of the NMR data has allowed determination of the site for lipase-catalyzed ring-opening polymerization of ε-CL. Our study suggests that among the possible four initiation sites in EGP only the hydroxyl group on carbon C-6 took part in the initiation process.
- Bisht,Gross,Cholli
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p. 1472 - 1478
(2007/10/03)
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- Monoesters of glycosides and a process for enzymatic preparation thereof
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Compounds of the formula (R-COO)n X-OR1, wherein R1 is optionally substituted alkyl, phenyl, or alkyl phenyl, n is 1, 2 or 3, X is a carbohydrate moiety, and R is optionally substituted alkyl, have superior effects as additives in detergents. These compounds can be prepared by esterification of glycosides using specific enzymes.
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- Enzyme-catalysed synthesis of alkyl β-D-Glucosides in organic media
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The synthetic potential of Almond β-D-Glucosidase for the synthesis of alkyl glucosides was studied. The regio and stereoselectivity of the synthesis were analysed for the reverse hydrolysis and the transglucosylation methods in tert-butanol and acetonitrile media.
- Vic, Gabin,Thomas, Daniel
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p. 4567 - 4570
(2007/10/02)
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- An improved procedure for the regioselective acetylation of monosaccharide derivatives by pancreatin-catalyzed transesterification in organic solvents
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A series of pyranoside and furanosidic monosaccharide derivatives were monoacetylated in the 6-position with high regioselectivity and good to excellent yields by the pancreatin-catalyzed transesterification with vinyl acetate in the solvent system tetrahydrofuran/triethylamine.
- Theil,Schick
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p. 533 - 535
(2007/10/02)
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- Enzyme Catalysed Preparation of 6-O-Acylglucopyranosides
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6-O-Monoesters of alkyl glucopyranosides have been prepared on a large scale in a more than 90percent yield by direct enzyme-catalysed esterification of glucopyranosides with long chain fatty acids in a solvent-free process.
- Adelhorst, Kim,Bjoerkling, Fredrik,Godtfredsen, Sven Erik,Kirk, Ole
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p. 112 - 115
(2007/10/02)
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- A novel approach to the synthesis of variety of aminodeoxy-α-D-glycopyranosides
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Conditions for the replacement of the 3-acetoxy-group of ethyl 3,4,6-tri-O-acetyl-2-deoxy-2-oximino-α-D-arabino-hexopyranoside (1) by nucleophiles including azide, phthalimide, hydride, and thiophenoxide are reported.The reaction was discovered through the formation of dimeric and trimeric derivatives of deacetylated 1 in the course of its alkaline hydrolysis.The possible use of the replacement reaction to achieve precursors for the formation of 3-deoxy-, 3-amino-3-deoxy-, 2-amino-2,3-dideoxy-, 2,3-diamino-2,3-dideoxy-, and 2-amino-2,3,4-trideoxy-α-D-glycopyranosides is demonstrated.
- Lemieux, Raymond U.,Georges, Fawzy F. Z.,Smiatacz, Zygfryd
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p. 1433 - 1438
(2007/10/02)
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- Solvolysis of D-Glucopyranosyl Derivatives in Mixtures of Ethanol and 2,2,2-Trifluoroethanol
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The products of solvolysis of α- and β-D-glucopyranosyl fluorides, 2,4-dinitrophenyl β-D-glucopyranoside, and the trifluoromethanesulfonates of the β-D-glucopyranosyl 3-bromopyridinium and α-D-glucopyranosyl 4-methylpyridinium ions in an equimolar mixture of ethanol and trifluoroethanol buffered with ca. 2 equiv of 2,6-lutidine have been examined by GLC of their trimethylsilyl ethers.The initial products of the solvolyses of phenyl α- and β-D-glucopyranosides catalyzed by trifluoromethanesulfonic acid in an equimolar mixture of ethanol and trifluoroethanol, and the products of uncatalyzed solvolysis of β-D-glucopyranosyl-p-nitrophenyltriazene, have been likewise examined.The composition of the medium for solvolysis of the glucosyl fluorides has also been systematically varied from pure ethanol to pure trifluoroethanol.The percentage of products with the same anomeric configuration as the starting material is in the range 8.1-88.5percent; change of leaving group, at constant anomeric configuration, or of anomeric configuration, at constant leaving group, yields different product distributions.Therefore the transition state for the product-determining step contains the leaving group.The preference for attack by ethanol as compared with trifluoroethanol varies from 0.9 to 20 in a way which shows no general systematic distinction between pathways for retention or inversion.The nucleophilic selectivity for retention is lowered by anionic leaving groups, especially fluoride, which preferentially stabilize the transition state containing trifluoroethanol by hydrogen bonding.Nucleophilic attack at the α face is preferred over nucleophilic attack at the β face, and exibits a lower selectivity: this is ascribed to hydrogen bonding between the oxygen atom of the 2-hydroxyl group and the hydroxyl group of the approaching alcohol.A model for solvolysis involving a reversibly formed ion pair or encounter complex is incompatible with the selectivities still observed with leaving groups less nucleophilic than the solvent components: a model involving selection between the components of a pool of solvent molecules by an irreversibly formed ion pair or encounter complex requires an implausibly large pool to explain observed specificities.It is therefore concluded that the observed selectivities are a consequence of the facilitation of the departure of the leaving group by the solvent, from either side of the reaction center.
- Sinnott, Michael L.,Jencks, William P.
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p. 2026 - 2032
(2007/10/02)
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