- Aqueous oxidation of sugars into sugar acids using hydrotalcite-supported gold nanoparticle catalyst under atmospheric molecular oxygen
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Hydrotalcite-supported gold nanoparticles show good activity as a heterogeneous catalyst for the oxidation of monosaccharides (xylose, ribose, galactose and mannose) and disaccharides (lactose and cellobiose) into the corresponding sugar acids under external base-free conditions in water solvent using atmospheric pressure of molecular oxygen. The produced sugar acids were thoroughly identified by 1H-, 13C-, and HMQC-NMR and ESI-FT-ICR MS spectroscopic techniques.
- Tomar, Ravi,Sharma, Jatin,Nishimura, Shun,Ebitani, Kohki
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supporting information
p. 843 - 845
(2016/07/16)
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- Gold as active phase of BN-supported catalysts for lactose oxidation
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Au/h-BN catalysts have been prepared by wet impregnation in order to combine the high activity of gold with the promising h-BN support to optimize the catalytic performances in lactose oxidation. After 1 h reaction, the catalysts were more active than all the Pd/h-BN catalysts described in previous works: 100% yield was reached after 2 h for a Au/h-BN catalyst prepared in water and containing only 1 wt.% of gold. The influence of α-Al2O3, γ-Al2O3 and Cblack as supports for Au was compared to h-BN and Au/α-Al2O3 was the most active. All of them exhibited 100% selectivity toward lactobionic acid. After a second run, Au/γ-Al2O3 presented a loss of selectivity and all were less active than during their first run. Au/h-BN and Au/α-Al2O3 have been regenerated and a thermal treatment permits to keep the catalysts active with 100% selectivity. Au/h-BN was the most active after regeneration thanks to the more facile poison removal from its surface and the high stability of boron nitride.
- Meyer, Nathalie,Renders, Coralie,Lanckman, Rapha?l,Devillers, Michel,Hermans, Sophie
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p. 549 - 558
(2015/01/30)
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- Boron nitride as an alternative support of Pd catalysts for the selective oxidation of lactose
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The potential of boron nitride as innovative support for the selective oxidation of carbohydrates has been evaluated. Pd/h-BN catalysts as well as Pd/α-Al2O3 have been synthesized by two different methods for comparison: dry impregnation and deposition-precipitation. It is shown that BN is a suitable alternative to alumina and carbon for sugar oxidation in liquid phase. Very active and selective Pd/h-BN catalysts were obtained by the two synthetic methods under consideration.
- Meyer, Nathalie,Bekaert, Kevin,Pirson, Damien,Devillers, Michel,Hermans, Sophie
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p. 170 - 174
(2013/01/15)
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- Selective production of lactobionic acid by aerobic oxidation of lactose over gold crystallites supported on mesoporous silica
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Partial oxidation of lactose over Au-based catalyst system using nanostructured silica materials with improved activity, selectivity and stability was investigated as a novel chemo-catalytic approach for selective synthesis of lactobionic acid (LBA) for therapeutic, pharmaceutical and food grad applications. Highly active gold crystallites dispersed on mesoporous silica (SiO2-meso) using bis-[3-(triethoxysilyl) propyl] tetrasulfide (BTSPT), a silane coupling agent to immobilize gold, were successfully formulated, and their catalytic activity was evaluated in an agitated semi-batch reactor. The catalysts were characterized by N2 physisorption, XRD, XPS and TEM. The influence of the reaction conditions, i.e., temperature, pH value, metal loading and catalyst/lactose ratio on lactose conversion were investigated. After 100 min of reaction, the catalyst containing 0.7% Au showed the highest catalytic activity (100% lactose conversion) and a 100% selectivity towards LBA, when it was used at a catalyst/lactose ratio of 0.2 under alkaline (pH 9.0) and mild reaction temperature (65 °C).
- Gutierrez, Luis-Felipe,Hamoudi, Safia,Belkacemi, Khaled
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body text
p. 94 - 103
(2012/04/10)
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- Production of lactose-free galacto-oligosaccharide mixtures: comparison of two cellobiose dehydrogenases for the selective oxidation of lactose to lactobionic acid
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Galacto-oligosaccharides, complex mixtures of various sugars, are produced by transgalactosylation from lactose using β-galactosidase and are of great interest for food and feed applications because of their prebiotic properties. Most galacto-oligosaccharide preparations currently available in the market contain a significant amount of monosaccharides and lactose. The mixture of galacto-oligosaccharides (GalOS) in this study produced from lactose using recombinant β-galactosidase from Lactobacillus reuteri contains 48% monosaccharides, 26.5% lactose and 25.5% GalOS. To remove efficiently both monosaccharides and lactose from this GalOS mixture containing significant amounts of prebiotic non-lactose disaccharides, a biocatalytic approach coupled with subsequent chromatographic steps was used. Lactose was first oxidised to lactobionic acid using fungal cellobiose dehydrogenases, and then lactobionic acid and monosaccharides were removed by ion-exchange and size-exclusion chromatography. Two different cellobiose dehydrogenases (CDH), originating from Sclerotium rolfsii and Myriococcum thermophilum, were compared with respect to their applicability for this process. CDH from S. rolfsii showed higher specificity for the substrate lactose, and only few other components of the GalOS mixture were oxidised during prolonged incubation. Since these sugars were only converted once lactose oxidation was almost complete, careful control of the CDH-catalysed reaction will significantly reduce the undesired oxidation, and hence subsequent removal, of any GalOS components. Removal of ions and monosaccharides by the chromatographic steps gave an essentially pure GalOS product, containing less than 0.3% lactose and monosaccharides, in a yield of 60.3%.
- Maischberger, Thomas,Nguyen, Thu-Ha,Sukyai, Prakit,Kittl, Roman,Riva, Sergio,Ludwig, Roland,Haltrich, Dietmar
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p. 2140 - 2147
(2008/12/21)
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- Catalytic Wet Oxidation of Lactose
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A process for converting lactose into carbon dioxide and/or carbon monoxide using catalytic wet oxidation. Oxygen gas and an aqueous solution of lactose are fed to a reactor comprising a Pt/Al2O3 catalyst, a Mn/Ce catalyst or a Pt/Mn—Ce catalyst, and the lactose is oxidized in the reactor at elevated temperature and pressure to produce at least one of small organic acids, carbon dioxide, carbon monoxide, water and combinations thereof. The small organic acids may be further degraded by feeding the small organic acids and oxygen gas into a reactor containing a Mn/Ce catalyst and oxidizing the small organic acids to water and at least one of carbon dioxide, carbon monoxide and combinations thereof.
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Page/Page column 16-18; sheet 26-29
(2008/06/13)
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- Synthesis and preliminary biological studies of hemifluorinated bifunctional bolaamphiphiles designed for gene delivery
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The multistep synthesis of a new series of dissymmetric hemifluorocarbon bolaamphiphiles designed for gene transport is described. The dissymmetric functionalization of diiodoperfluoroctane leads to bolaamphiphile molecules composed of a partially fluorocarbon core end-capped with a glycoside and an ammonium salt derived from histidine or lysine. Initial biological results indicate that one of the bolaamphiphile - end-capped with a lysine and a lactobionamide residue - induces a remarkably low cytotoxicity on COS-7 cells and, when self-assembled with DNA plasmid, generates a significant in vitro transfection efficiency without the addition of any fusogenic lipid. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.
- Denoyelle, Severine,Polidori, Ange,Brunelle, Melanie,Vuillaume, Pascal Y.,Laurent, Sylvette,ElAzhary, Yousef,Pucci, Bernard
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p. 629 - 646
(2007/10/03)
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- METHOD FOR SELECTIVE CARBOHYDRATE OXIDATION USING SUPPORTED GOLD CATALYSTS
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The invention relates to a method for the selective oxidation of a carbohydrate in the presence of a gold catalyst comprising gold particles distributed in a nanodispersed manner on a metal oxide support, and to a method for the selective oxidation of an oligosaccharide in the presence of a gold catalyst comprising gold particles distributed in a nanodispersed manner on a carbon or metal oxide support. The invention also relates to aldonic acid oxidation products produced using said method.
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Page/Page column 52-53
(2010/02/09)
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- Pd(II) inhibition during hexacyanoferrate (III) oxidation of sugars: a kinetic study
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An inhibition effect of PdCl2 on the rate of oxidation of sugars, by alkaline hexacyano-ferrate(III) has been observed. The order of reactions in hexacyanoferrate(III) and OH- is zero and unity, respectively, while that in sugars decreases from unity at higher sugar concentration. The kinetic data and spectrophotometric evidence support the formation of {PdII - (sugar)} and {PdII - sugar)2} complexes and their resistance to react with Fe(CN)63-.
- Bajpai,Shukla,Upadhyay
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p. 413 - 419
(2007/10/03)
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