Kinetic analysis of hexose conversion to methyl lactate by Sn-Beta: effects of substrate masking and of water

Tosi, Irène; Riisager, Anders; Taarning, Esben; Jensen, Pernille Rose; Meier, Sebastián

doi:10.1039/c8cy00335a

Cited by 35 publications

(59 citation statements)

References 39 publications

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“…These findings underline that erythrulose can isomerize to some degree to its aldose tautomers [17] under the current reaction conditions and that acetals form poorlyreactive, masked byproducts in the conversion of carbohydrates in alcohols ( Figure S1). [18] The signals of the substrate erythrulose and HA-MEG intermediate both approach zero and the conversions were treated as overall irreversible steps. Resultant fits of reaction progress curves to a consecutive two-step kinetic model are shown in Figure 4 and the obtained rate constants are plotted on a logarithmic scale versus the inverse absolute temperature for Eyring analysis in Figure 5.…”

Section: Real Time Nmr Of the Acyclic Pathway At Different Temperaturesmentioning

confidence: 99%

Probing the Lewis Acid Catalyzed Acyclic Pathway of Carbohydrate Conversion in Methanol by In Situ NMR

2019

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Future bioindustries will rely on the formation of diverse chemicals at high yield through various reaction pathways. These pathways include reactions to a series of alpha‐hydroxy esters and acids that can be formed from the conversion of C3–C6 carbohydrates by Lewis acidic catalysts in alcohols and water. Definitive kinetic and mechanistic insights to support the development of carbohydrate conversion processes are arguably less developed than for analogous biocatalytic processes. Here, we visualize acyclic pathways of carbohydrate dehydration, using the acyclic C4 carbohydrate erythrulose as a probe molecule for the conversion by homogeneous SnCl4 in methanol. In situ studies allow the detection of previously postulated intermediates, identify the branch point to competing products and provide energetic and mechanistic insight by kinetic analysis. Reversibility of reactions, stereoselectivity and differential propensity for deuterium incorporation in competing pathways can be tracked by the formation of compounds with asymmetric mass distribution.

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Section: Real Time Nmr Of the Acyclic Pathway At Different Temperaturesmentioning

confidence: 99%

Probing the Lewis Acid Catalyzed Acyclic Pathway of Carbohydrate Conversion in Methanol by In Situ NMR

2019

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“…Due to its fairly easy degradation into monomeric fructose [34], inulin was chosen as substrate to investigate the benefits of mesoporous systems, without introducing major obstacles in the form of recalcitrance in an additional step of polymer solvolysis. The crude reaction mixtures were analyzed by 2D NMR [35]. Particularly, 1 H-13 C HSQC allowed the distinction of the different sugars and methyl glycosides in their α/β-anomeric and pyranoside/furanoside forms ( Figure 5).…”

Section: Catalytic Performancementioning

confidence: 99%

“…However, the yields at full conversion are not appropriate indicators of changes in catalytic activity. In fact, methyl fructosides are considered intermediate products in the process [35], which easily hydrolyze in the presence of water to yield fructose as a substrate for the formation of methyl lactate (or other bio-based chemicals) on a longer time scale [38]. All the modified systems showed increased production of these intermediates and a little change to the formation of the desired product.…”

Section: Catalytic Performancementioning

confidence: 99%

Exploring the Synthesis of Mesoporous Stannosilicates as Catalysts for the Conversion of Mono- and Oligosaccharides into Methyl Lactate

et al. 2019

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Sn-Beta zeolites are among the most promising catalysts for the conversion of biomasses due to their high Lewis acidity, which allows coordination to functionalized molecules and promotes cleavage and rearrangement reactions. For applications in biorefining zeolite porosity would ideally be optimized to avoid diffusional limitations, which otherwise may decrease reaction rates and restrict the conversion of bulky substrates. The synthesis of mesoporous zeolites can help alleviating limitations and is a central topic in heterogeneous catalysis, with many synthetic procedures for mesoporous zeolites proposed over the last decades. Here, we explore different syntheses routes to prepare Lewis acidic Sn-containing zeolites, and the main features of the prepared mesoporous materials are characterized. We investigate the correlation between different types of porosity and the activity for the conversion of sugars into methyl lactate. The monomer glucose, the dimer sucrose and the oligomer inulin are applied as model substrates for the reaction in order to probe the accessibility of molecules with different sizes to active sites in zeolites with different pore systems.

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“…However, the aforementioned studies investigated the tin-based zeotypes for efficient production of lactates, and little attention was paid to the systematic investigation of kinetic and mechanistic understanding in the Sn-Betacatalyzed lactates course. With regard to this, Tosi et al designed the relatively detailed kinetic analysis of fructose, glucose, and sucrose transformation to ML through typical Sn-Beta [125]. Emphasis was focused on the influence of substrate masking and water using 1D and 2D NMR spectroscopy method.…”

Section: Sugars Tomentioning

confidence: 99%

Chemocatalytic Production of Lactates from Biomass-Derived Sugars

Zhang

et al. 2018

International Journal of Chemical Engineering

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In recent decades, a great deal of attention has been paid to the exploration of alternative and sustainable resources to produce biofuels and valuable chemicals, with aims of reducing the reliance on depleting confined fossil resources and alleviating serious economic and environmental issues. In line with this, lignocellulosic biomass-derived lactic acid (LA, 2-hydroxypropanoic acid), to be identified as an important biomass-derived commodity chemical, has found wide applications in food, pharmaceuticals, and cosmetics. In spite of the current fermentation of saccharides to produce lactic acid, sustainability issues such as environmental impact and high cost derived from the relative separation and purification process will be growing with the increasing demands of necessary orders. Alternatively, chemocatalytic approaches to manufacture LA from biomass (i.e., inedible cellulose) have attracted extensive attention, which may give rise to higher productivity and lower costs related to product work-up. is work presents a review of the state-of-the-art for the production of LA using homogeneous, heterogeneous acid, and base catalysts, from sugars and real biomass like rice straw, respectively. Furthermore, the corresponding bio-based esters lactate which could serve as green solvents, produced from biomass with chemocatalysis, is also discussed. Advantages of heterogeneous catalytic reaction systems are emphasized. Guidance is suggested to improve the catalytic performance of heterogeneous catalysts for the production of LA.

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Kinetic analysis of hexose conversion to methyl lactate by Sn-Beta: effects of substrate masking and of water

Abstract: Strategies to tailor the Sn-Beta-catalysed methyl lactate process are identified by kinetic and mechanistic insights.

Cited by 35 publications

References 39 publications

Probing the Lewis Acid Catalyzed Acyclic Pathway of Carbohydrate Conversion in Methanol by In Situ NMR

Probing the Lewis Acid Catalyzed Acyclic Pathway of Carbohydrate Conversion in Methanol by In Situ NMR

Exploring the Synthesis of Mesoporous Stannosilicates as Catalysts for the Conversion of Mono- and Oligosaccharides into Methyl Lactate

Chemocatalytic Production of Lactates from Biomass-Derived Sugars

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