526-92-1Relevant academic research and scientific papers
Selective Conversion of Various Monosaccharaides into Sugar Acids by Additive-Free Dehydrogenation in Water
Mollar-Cuni, Andres,Byrne, Joseph P.,Borja, Pilar,Vicent, Cristian,Albrecht, Martin,Mata, Jose A.
, p. 3746 - 3752 (2020/06/01)
Abundant sugars of five and six carbon atoms are promising candidates for the production of valuable platform chemicals. Here, we describe the catalytic dehydrogenation of several pentoses and hexoses into their corresponding sugar acids with the concomitant formation of molecular hydrogen. This biomass transformation is promoted by highly active and selective catalysts based on iridium(III) complexes containing a triazolylidene (trz) as ligand. Monosaccharides are converted into sugar acids in an easy and sustainable manner using only catalyst and water, and in contrast to previously reported procedures, in the absence of any additive. The reaction is therefore very clean, and highly selective, which avoids the tedious purification and product separation. Mechanistic investigations using 1H NMR and UV-vis spectroscopies and ESI mass spectrometry (ESI-MS) indicate the formation of an unprecedented diiridium-hydride as dormant species that correspond to the catalyst resting state.
Upgrading of Biomass Monosaccharides by Immobilized Glucose Dehydrogenase and Xylose Dehydrogenase
Zdarta, Jakub,Pinelo, Manuel,Jesionowski, Teofil,Meyer, Anne S.
, p. 5164 - 5173 (2018/10/25)
Direct upgrading and separation of the monosaccharides from biomass liquors is an overlooked area. In this work we demonstrate enzymatic production of gluconic acid and xylonic acid from glucose and xylose present in pretreated birchwood liquor by glucose dehydrogenase (GDH, EC 1.1.1.47) and xylose dehydrogenase (XDH, EC 1.1.1.175), respectively. The biocatalytic conversions were compared using two different kinds of silica support materials (silica nanoparticles (nanoSiO2) and porous silica particles with hexagonal pores (SBA 15 silica) for enzyme immobilization. Upon immobilization, both enzymes showed significant improvement in their thermal stability and robustness at alkaline pH and exhibited over 50 % activity even at pH 10 and 60 °C on both immobilization matrices. When compared to free enzymes at 45 °C, GDH immobilized on nanoSiO2 and SBA silica displayed a 4.5 and 7.25 fold increase in half-life, respectively, whilst XDH immobilized on nanoSiO2 and SBA showed a 4.7 and 9.5 fold improvement in half-life, respectively. Additionally, after five reaction cycles both nanoSiO2GDH and nanoSiO2XDH retained more than 40 % activity and GDH and XDH immobilized on SBA silica maintained around 50 % of their initial activity resulting in about 1.5–1.6 fold increase in biocatalytic productivity compared to the free enzymes.
Aerobic oxidation of xylose to xylaric acid in water over pt catalysts
Sadula, Sunitha,Saha, Basudeb
, p. 2124 - 2129 (2018/10/20)
Energy-efficient catalytic conversion of biomass intermediates to functional chemicals can make bio-products viable. Herein, we report an efficient and low temperature aerobic oxidation of xylose to xylaric acid, a promising bio-based chemical for the production of glutaric acid, over commercial catalysts in water. Among several heterogeneous catalysts investigated, Pt/ C exhibits the best activity. Systematic variation of reaction parameters in the pH range of 2.5 to 10 suggests that the reaction is fast at higher temperatures but high C C scission of intermediate C5-oxidized products to low carbon carboxylic acids undermines xylaric acid selectivity. The C C cleavage is also high in basic solution. The oxidation at neutral pH and 60 8C achieves the highest xylaric acid yield (64 %). O2 pressure and Pt amount have significant influence on the reactivity. Decar-boxylation of short chain carboxylic acids results in formation of CO2, causing some carbon loss; however, such decarboxyla-tion is slow in the presence of xylose. The catalyst retained comparable activity, in terms of product selectivity, after five cycles with no sign of Pt leaching.
Highly selective photocatalytic oxidation of biomass-derived chemicals to carboxyl compounds over Au/TiO2
Zhou, Baowen,Song, Jinliang,Zhang, Zhanrong,Jiang, Zhiwei,Zhang, Pei,Han, Buxing
, p. 1075 - 1081 (2017/03/17)
Highly selective transformation of biomass-derived chemicals into value-added chemicals is of great importance. In this work, selective photooxidation of various biomass-derived chemicals, including ethanol, glucose, xylose, 2-furaldehyde, 5-hydroxymethyl-2-furfural, and furfuralcohol to the corresponding carboxyl compounds was studied using atmospheric air as the oxidant at ambient temperature. It was found that the reactions could be carried out efficiently over Au nanoparticles (AuNPs) supported on TiO2 (AuNPs/TiO2) under both ultraviolet (UV) and visible light in Na2CO3 aqueous solution. Under the optimized conditions, the selectivities for desired products were higher than 95% for all the reactions. Detailed studies indicated that the surface plasmon resonance of AuNPs and the band-gap photoexcitation of TiO2 were responsible for visible-light-responding and UV-light-responding activities, respectively. Na2CO3 acted as the promoter for the visible-light-induced oxidation and the inhibitor of reactive oxygen species with strong oxidation power under UV light.
Expanding the reaction space of aldolases using hydroxypyruvate as a nucleophilic substrate
De Berardinis, Véronique,Guérard-Hélaine, Christine,Darii, Ekaterina,Bastard, Karine,Hélaine, Virgil,Mariage, Aline,Petit, Jean-Louis,Poupard, Nicolas,Sánchez-Moreno, Israel,Stam, Mark,Gefflaut, Thierry,Salanoubat, Marcel,Lemaire, Marielle
, p. 519 - 526 (2017/08/14)
Aldolases are key biocatalysts for stereoselective C-C bond formation allowing access to polyoxygenated chiral units through direct, efficient, and sustainable synthetic processes. The aldol reaction involving unprotected hydroxypyruvate and an aldehyde offers access to valuable polyhydroxy-α-keto acids. However, this undescribed aldolisation is highly challenging, especially regarding stereoselectivity. This reaction was explored using, as biocatalysts, a collection of aldolases selected from biodiversity. Several enzymes that belong to the same pyruvate aldolase Pfam family (PF03328) were found to produce the desired hexulosonic acids from hydroxypyruvate and d-glyceraldehyde with complementary stereoselectivities. One of them was selected for the proof of concept as a biocatalytic tool to prepare five (3S,4S) aldol adducts through an eco-friendly process.
Solid base supported metal catalysts for the oxidation and hydrogenation of sugars
Tathod, Anup,Kane, Tanushree,Sanil,Dhepe, Paresh L.
, p. 90 - 99 (2014/06/09)
Pt impregnated on γ-Al2O3 (acidic support) and hydrotalcite (basic support) catalysts were synthesized, characterized and used in the oxidation and hydrogenation reactions of C5 and C6 sugars. In the absence of homogeneous base, 83% yield for gluconic acid; an oxidation product of glucose can be achieved over Pt/hydrotalcite (HT) catalyst at 50 °C under atmospheric oxygen pressure. Similarly, 57% yield for xylonic acid, an oxidation product of xylose is also possible over Pt/HT catalyst. Hydrogenation of glucose conducted using Pt/γ-Al2O3 + HT catalytic system showed 68% sugar alcohols (sorbitol + mannitol) formation. The 82% yield for C5 sugar alcohols (xylitol + arabitol) was obtained by subjecting xylose to hydrogenation over Pt/γ-Al2O3 + HT at 60 °C. UV analysis helped to establish the fact that under alkaline conditions sugars prefer to remain in open chain form in the solution and thus exposes CHO group which further undergoes oxidation and hydrogenation reactions to yield acids and alcohols.
Kinetic and mechanistic investigation of Pd(II)-catalysed and Hg(II)-co-catalysed oxidation of d(+)melibiose by N-bromoacetamide in acidic medium
Singh, Ashok Kumar,Yadav, Sarita,Srivastava, Rashmi,Srivastava, Jaya,Rahmani, Shahla
experimental part, p. 2213 - 2219 (2010/10/04)
The kinetic and mechanistic study of homogeneously Pd(II)-catalysed and Hg(II)-co-catalysed oxidation of d(+)melibiose (mel) by N-bromoacetamide (NBA) in perchloric acid medium have been made at temperature 40 °C ± 0.1 °C. Kinetic results show first-order kinetics with respect to NBA at its low concentrations, tending to zero-order at its high concentrations. The oxidation rate is directly proportional to [Pd(II)] and [sugar], indicating first-order kinetics with respect to Pd(II) and sugar. Zero effect of Cl- and H+ ions throughout their variation have been noted. First-order kinetics with respect to Hg(II) at its low concentration tends to zero-order at its higher concentration. Addition of acetamide (NHA) decreases the first-order rate constant (k1) while the rate of reaction is not influenced by the change in ionic strength (μ) of the medium. The first-order rate constant decreases with an increase in dielectric constant of the medium. Arabinonic acid, lyxonic acid and formic acid were identified as oxidation products of the reaction. Various activation parameters including the entropy of activation were also calculated. A plausible mechanism conforming to kinetic data, spectrophotometric observations, reaction stoichiometry and product analysis has been proposed.
Solubilization, purification, and properties of membrane-bound D-glucono-δ-lactone hydrolase from Gluconobacter oxydans
Shinagawa, Emiko,Ano, Yoshitaka,Yakushi, Toshiharu,Adachi, Osao,Matsushita, Kazunobu
body text, p. 241 - 244 (2009/06/20)
Membrane-bound glucono-δ-lactonase (MGL) was purified to homogeneity from the membrane fraction of Gluconobacter oxydans IFO 3244. After solubilization with 1 M CaCl2, MGL was purified in the presence of Ca2+ and detergent. A single
NOVEL REACTION WITH A GOLD CATALYST
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Page/Page column 21-23, (2009/01/24)
The invention relates to a process for the catalytic conversion of a carbohydrate, an alcohol, an aldehyde or a polyhydroxy compound in the presence of a catalyst containing gold in a solvent.
Kinetics and mechanism of oxidation of some aldoses by hexacyanoferrate(III) ions in aqueous alkaline buffered medium
Goel, Anjali,Shailja,Ruchi
experimental part, p. 286 - 289 (2009/06/25)
Kinetics of oxidation of some aldoses like glucose, galactose, xylose and ribose by hexacyanoferrate(III) ions in aqueous alkaline buttered medium has been investigated. The kinetic results indicate the zero-order kinetics in hexacyanoferrate(III) and first-order in aldoses and OH-. The ionic strength of the medium has no influence on oxidation rate. Various activation parameters were also calculated at four different temperatures : 30, 35, 40 and 45°C. The corresponding acids were identified as the main oxidation products of the reaction. A suitable mechanism consistent with experimental findings has been proposed.
