A Computational Study on the Mechanism of the Formose Reaction Catalyzed by the Thiazolium Salt.

Tajima, Hideo; Inoue, Hakuai; Ito, Masato

doi:10.2477/jccj.2.127

Cited by 8 publications

(7 citation statements)

References 20 publications

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“…Base-catalyzed self-condensation of formaldehyde to glycoaldehyde is known in the literature. , Subsequent hydrogenation of glycoaldehyde can produce ethanol as shown in eqs and , respectively. 2HCHO → HOCH 2 CHO HOCH 2 CHO → CH 3 CH 2 OH …”

Section: Catalystsmentioning

confidence: 99%

“…Glycoaldehyde can also be formed by the insertion of CO in formaldehyde followed by hydrogenation over Rh-based catalysts. In fact, ethylene glycol has been produced by the reaction of formaldehyde with syngas as shown in eqs and . , H C H O + C O + H 2 → HOCH 2 CHO HOCH 2 C H O + H 2 → HOCH 2 CH 2 OH …”

Section: Catalystsmentioning

confidence: 99%

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A Review of Recent Literature to Search for an Efficient Catalytic Process for the Conversion of Syngas to Ethanol

2008

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Alternatives to petroleum-derived fuels and chemicals are being sought in an effort to improve air quality and increase energy security through development of novel technologies for the production of synthetic fuels and chemicals using renewable energy sources such as biomass. In this context, ethanol is being considered as a potential alternative synthetic fuel to be used in automobiles or as a potential source of hydrogen for fuel cells as it can be produced from biomass. Renewable ethanol can also serve as a feedstock for the synthesis of a variety of industrial chemicals and polymers. Currently, ethanol is produced primarily by fermentation of biomass-derived sugars, especially those containing six carbons, whereas 5-carbon sugars and lignin, which are also present in the biomass, remain unusable. Gasification of biomass to syngas (CO + H 2 ), followed by catalytic conversion of syngas, could produce ethanol in large quantities. However, the catalytic conversion of syngas to ethanol remains challenging, and no commercial process exists as of today although the research on this topic has been ongoing for the past 90 years. Both homogeneous and heterogeneous catalytic processes have been reported. The homogeneous catalytic processes are relatively more selective for ethanol. However, the need for expensive catalyst, high operating pressure, and the tedious workup procedures involved for catalyst separation and recycling make these processes unattractive for commercial applications. The heterogeneous catalytic processes for converting syngas to ethanol suffer from low yield and poor selectivity due to slow kinetics of the initial C-C bond formation and fast chain growth of the C 2 intermediate. Recently, there is a growing worldwide interest in the conversion of syngas to ethanol. Significant improvements in catalyst design and process development need to be achieved to make this conversion commercially attractive. This paper reviews and critically assesses various catalytic routes reported in the recent past for the conversion of syngas to higher alcohols, with an emphasis on ethanol. The chemistry and thermodynamics of the processes, the type of catalysts developed, reactors used, and the current status of the technology are reviewed and discussed.

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Section: Catalystsmentioning

confidence: 99%

Section: Catalystsmentioning

confidence: 99%

A Review of Recent Literature to Search for an Efficient Catalytic Process for the Conversion of Syngas to Ethanol

2008

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“…[15] For example, when triethylamine is employed as a base, its concentration should be equal to that of the thiazolium salt to provide the maximal efficiency by stabilization of the zwitterion intermediate by ion-pairing with the ammonium ion as predicted by theoretical studies. [91] Variation of the initial concentration of formaldehyde, its ratio to the concentration of the thiazolium catalyst, the nature of the basic catalyst and of the solvent opens an opportunity for governing the selectivity of the synthesis for the production of a target monosaccharide. Thus, preferential syntheses of dihydroxyacetone, [92] DL-glycerotetrulose, [92] Scheme 8.…”

Section: Thiazolium-catalyzed Oligomerization Of Formaldehydementioning

confidence: 99%

Catalytic Formation of Monosaccharides: From the Formose Reaction towards Selective Synthesis

et al. 2014

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The formose reaction (FR) has been long the focus of intensive investigations as a simple method for synthesis of complex biologically important monosaccharides and other sugar-like molecules from the simplest organic substrate-formaldehyde. The fundamental importance of the FR is predominantly connected with the ascertainment of plausible scenarios of chemical evolution which could have occurred on the prebiotic Earth to produce the very first molecules of carbohydrates, amino- and nucleic acids, as well as other vitally important substances. The practical importance of studies on the FR is the elaboration of catalytic methods for the synthesis of rare and non-natural monosaccharides and polyols. This Minireview considers the FR from the point of view of chemists working in the field of catalysis with emphasis on the mechanisms of numerous parallel and consequent catalytic transformations that take place during the FR. Based on its kinetics, the FR may be considered as a non-radical chain process with degenerate branching. The Minireview also considers different approaches to the control of selectivity of carbohydrate synthesis from formaldehyde and lower monosaccharides.

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“…These were also the conditions used in our previous studies on the self-oligomerization of aldehydes. − We are not the first to use computational methods to study some of the reactions in the present system; however, to our knowledge we are the first to systematically provide a broad map of the energy landscape for formaldehyde oligomerization. Previous studies − typically (1) concentrated on isolated reactions of interest, (2) were for gas-phase conditions, and/or (3) were performed semiempirically.…”

Section: Introductionmentioning

confidence: 99%

Mapping the Kinetic and Thermodynamic Landscape of Formaldehyde Oligomerization under Neutral Conditions

et al. 2013

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Density functional theory calculations, including Poisson-Boltzmann implicit solvent and free energy corrections, are applied to study the thermodynamic and kinetic free energy landscape of formaldehyde oligomerization up to the C4 species in aqueous solution at pH 7. Oligomerization via C-O bond formation leads to linear polyoxymethylene (POM) species, which are the most kinetically accessible oligomers and are marginally thermodynamically favored over their oxane ring counterparts. On the other hand, C-C bond formation via aldol reactions leads to sugars that are thermodynamically much more stable in free energy than POM species; however, the barrier to dimerization is very high. Once this initial barrier is traversed, subsequent addition of monomers to generate trimers and tetramers is kinetically more feasible. In the aldol reaction, enolization of the oligomers provides the lowest energy pathway to larger oligomers. Our study provides a baseline free energy map for further study of oligomerization reactions under catalytic conditions, and we discuss how this will lead to a better understanding of complex reaction mixtures with multiple intermediates and products.

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A Computational Study on the Mechanism of the Formose Reaction Catalyzed by the Thiazolium Salt.

Cited by 8 publications

References 20 publications

A Review of Recent Literature to Search for an Efficient Catalytic Process for the Conversion of Syngas to Ethanol

A Review of Recent Literature to Search for an Efficient Catalytic Process for the Conversion of Syngas to Ethanol

Catalytic Formation of Monosaccharides: From the Formose Reaction towards Selective Synthesis

Mapping the Kinetic and Thermodynamic Landscape of Formaldehyde Oligomerization under Neutral Conditions

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