Comparative study of C(2) epimerization of d-glucose and d-mannose catalyzed by water soluble organometallic complexes with nitrogen ligands

Kolarić, Snježana; Šunjić, Vitomir

doi:10.1016/1381-1169(96)00089-1

Cited by 11 publications

(3 citation statements)

References 23 publications

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“…Mannose may be involved in a similar degradation pathway not yet identified. Another reason is that the isomerization , reaction ends up in glucose as the more stable form, causing the yields of fructose and mannose to be limited by the equilibrium of this reaction. , …”

Section: Resultsmentioning

confidence: 99%

Decomposition of Cellulose in Hot-Compressed Water: Detailed Analysis of the Products and Effect of Operating Conditions

et al. 2017

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Understanding the reaction pathways of cellulose hydrolysis in hot-compressed water (HCW) is crucial for the optimization of fermentable sugar and chemical production. Advanced analytical strategies are required to better assess the wide range of products from cellulose conversion in HCW. In this work, cellulose conversion in HCW was conducted in an autoclave with sampling upon the reaction time under isothermal conditions (180, 220, and 260 °C from 0 to 120 min). Total water-soluble carbohydrates were quantified (phenol/sulfuric acid method). These products were first characterized by size-exclusion chromatography coupled to evaporative light scattering detection and mass spectrometry (SEC–ELSD–MS). SEC is useful for screening the molecular weight distribution of soluble products. Then, the chemical structure of water solubles has been attributed by hydrophilic interaction liquid chromatography coupled to a linear trap quadrupole Orbitrap mass spectrometer (HILIC–LTQ–Orbitrap–MS). This method notably provides evidence of the formation of a cellobiose conformer under some HCW conditions. A specific high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC–PAD) method has been developed. This method allows for a selective separation of 5-hydroxymethylfurfural (5-HMF), glucose, fructose, mannose, and oligomers up to cellopentaose. Carboxylic acids were quantified by high-performance liquid chromatography with ultraviolet detection (HPLC–UV). Solid residues obtained after HCW conversion were characterized by X-ray diffraction (XRD) and permanent gas by micro-gas chromatography. The global reaction mechanism of cellulose liquefaction in HCW is rationalized on the basis of these complementary methods. Cellulose conversion first proceeds with heterogeneous hydrolysis (fiber surface) to produce soluble oligomers in competition with pyrolysis (inner fibers with limited mass transfer of water), producing levoglucosan (promoted at a higher temperature). Soluble oligomers produce glucose and isomers by homogeneous hydrolysis (liquid phase). C6 sugars can then undergo further conversion to produce notably 5-HMF and erythrose.

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Section: Resultsmentioning

confidence: 99%

Decomposition of Cellulose in Hot-Compressed Water: Detailed Analysis of the Products and Effect of Operating Conditions

et al. 2017

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“…18 Recently, organic amines have been reported as effective isomerization catalysts resulting in high fructose yields and selectivities, superior to those obtained with inorganic bases. 19 Soluble organometallic complexes 20 as well as, Lewis acid salts 21,22 have also been studied, while enhanced fructose yield in the presence of NaAlO 2 has been reported. 23,24 Heterogeneous catalytic systems are beneficial compared to homogeneous ones, owing to the facile separation and reuse of the solid catalysts.…”

Section: ■ Introductionmentioning

confidence: 99%

Isomerization of Glucose into Fructose over Natural and Synthetic MgO Catalysts

Marianou

Michailof

Ipsakis

et al. 2018

ACS Sustainable Chem. Eng.

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Fructose is one of the most important aldoses and has been gaining attention as the starting material for the synthesis of biobased platform and high-added value chemicals such as 5-hydroxymethylfurfural (5-HMF), levulinic acid and lactic acid. However, due to its low natural occurrence, fructose is produced from glucose, an abundant hexose, via isomerization. Currently, the conventional industrial process utilizes glucose isomerase as a catalyst and is therefore subjected to the limitations of enzymatic reactions. Consequently, an alternative efficient solid catalyst is required that will exhibit high activity, selectivity and stability/reusability. Toward this end, we have demonstrated the effectiveness of using natural MgO, derived from simple calcination of magnesite ores, as a low cost catalyst with increased basicity. A series of industrial and laboratory prepared natural MgO materials with different morphology, porosity and basicity were investigated and the optimum catalyst afforded 44.1 wt % glucose conversion and 75.8 wt % fructose selectivity (33.4 wt % fructose yield), at 90 °C for a 45 min reaction in aqueous solution. The activity of the MgO catalysts was directly correlated with their basicity, which in turn depended on their crystal size, surface area and composition. CaO impurities of the natural MgO materials generated strong basic sites that enhanced glucose conversion but at the expense of fructose selectivity. The stability and reuse of the optimum catalyst was confirmed for at least 4 cycles of reaction–regeneration, whereas the mechanism of glucose isomerization was validated via a first-order kinetic modeling set.

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“…Recently, organic amines have been reported as catalysts for the isomerization of glucose, leading to fructose yields and selectivities superior to those obtained with inorganic bases . Soluble organometallic complexes as well as Lewis acid salts have also been studied.…”

Section: Introductionmentioning

confidence: 99%

Glucose to Fructose Isomerization in Aqueous Media over Homogeneous and Heterogeneous Catalysts

et al. 2016

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Isomerization of glucose to fructose is an important reaction with numerous applications in terms of biomass valorization. The reaction is catalyzed enzymatically but may also proceed under alkaline conditions, in which case it is accompanied by low selectivity and formation of byproducts. Solid Lewis acid and basic catalytic materials are being studied as alternative catalysts. In this work, the isomerization of glucose to fructose in aqueous media over homogeneous and heterogeneous catalysts has been investigated. The effect of polar aprotic solvents and their mixtures with water on glucose conversion and fructose selectivity was also studied. Sodium aluminate (NaAlO2) has been proven to be very effective, resulting in high fructose yield (52.1 %) and high selectivity (84.8 %). Among the various solid catalysts tested, MgO afforded glucose conversion of 44 %, with 75.8 % and 33.4 % fructose selectivity and yield, respectively, when the isomerization reaction was conducted in neat H2O.

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Comparative study of C(2) epimerization of d-glucose and d-mannose catalyzed by water soluble organometallic complexes with nitrogen ligands

Cited by 11 publications

References 23 publications

Decomposition of Cellulose in Hot-Compressed Water: Detailed Analysis of the Products and Effect of Operating Conditions

Decomposition of Cellulose in Hot-Compressed Water: Detailed Analysis of the Products and Effect of Operating Conditions

Isomerization of Glucose into Fructose over Natural and Synthetic MgO Catalysts

Glucose to Fructose Isomerization in Aqueous Media over Homogeneous and Heterogeneous Catalysts

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