- Efficient visible-light-driven selective conversion of glucose to high-value chemicals over Bi2WO6/Co-thioporphyrazine composite in aqueous media
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Selective photocatalytic oxidation of glucose to high-value chemicals in aqueous media using atmospheric oxygen as oxidant and solar light as driving force is a greatly attractive topic. Herein, Bi2WO6/CoPz (cobalt tetra(2,3-bis(butylthio)maleonitrile) porphyrazine) composite was served as a visible-light photocatalyst towards selective oxidation of glucose to high-value arabinose and formic acid in aqueous media, which was performed under visible light (λ ≥ 420 nm) irradiation using atmospheric oxygen as oxidant. The reactive parameters for glucose oxidation, such as light intensity, CoPz content, glucose concentration and active species, were studied. The highest activity for Bi2WO6/CoPz composite was obtained when the CoPz content was 0.25 %. Under the optimum reaction conditions, 96.8 % of total selectivity towards arabinose and formic acid at 45.3 % of glucose conversion was obtained after reacting 3 h. The critical role of CoPz and the rationale behind the high photocatalytic performance for Bi2WO6/CoPz composite were further investigated using various techniques.
- Deng, Kejian,Ge, Yanchun,Yang, Changjun,Zhang, Bingguang,Zhang, Quanquan
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- Hydrogenolysis of cellulose combining mineral acids and hydrogenation catalysts
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A catalytic system capable of reaching high performance in the hydrogenolysis of cellulose at low reaction temperature and short reaction times has been developed. Therefore, supported noble metal catalysts based on Pt, Pd and Ru have been combined with dilute mineral acids. A broad variable set in terms of type of noble metal, type of acid, acid concentration and reaction time could be evaluated based on chemical interpretation and supported by a Design of Experiment (DoE) approach. The variables significantly influenced conversion of cellulose, product range and selectivity towards sugar alcohol formation. Thus, at 160 °C, above 60% yield in sugars and sugar alcohols with 84% selectivity at a cellulose conversion of 72% could be reached. Besides, glycerol, propylene glycol, ethylene glycol and methanol were formed as additional valuable by-products leading to an overall carbon utilization above 89%. Furthermore, the concept was successfully transferred to real feedstocks in the form of spruce reaching close to 60% conversion in only one hour reaction time.
- Palkovits, Regina,Tajvidi, Kameh,Procelewska, Joanna,Rinaldi, Roberto,Ruppert, Agnieszka
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scheme or table
p. 972 - 978
(2010/08/19)
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- Synthesis of racemic ribose from D-glucose
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Racemic ribose is a valuable starting material for investigations of the origins of biomolecular homochirality. It can be synthesized in seven steps starting from D-glucose.
- Miculka, Christian
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p. 948 - 950
(2007/10/03)
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- Kinetics, Catalysis, and Mechanism of the Secondary Reaction in the Final Phase of the Formose Reaction
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In the final phase of the formose reaction sugars are formed by the reaction of glycolaldehyde, glyceraldehyde and dihydroxyacetone.The application of high-pressure liquid chromatography allows for the first time to investigate intermediate and final products quantitatively.The results of kinetical investigations allow to suggest a reaction mechanism for the secondary reaction in the final phase of the formose reaction.This mechanism is compared with that of the starting phase and other known mechanisms.From the results metal ion-catalyzed aldol reactions have to be assumed.
- Harsch, Guenther,Bauer, Hermann,Voelter, Wolfgang
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p. 623 - 635
(2007/10/02)
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- THE FORMOIN REACTION
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The formoin reaction, i.e., the autocondensation of formaldehyde in an aprotic solvent catalysed by the conjugate base of a thiazolium ion, has been studied in detail.Glucose, galactose, dihyroxyacetone dimer, xylose, and arabinose have been identified as products.The influence of catalysts, temperature, basicity, and reaction time is documented.N,N-Dimethylformamide is a more convenient solvent than ether, benzene, or diglyme.Ethyldi-isopropylamine affords better yields of carbohydrate material than triethylamine.At =60 deg, aldol condensations are reduced to a minimum.After 1-2 h of reaction (depending on the conditions), the yields begin to decrease and become zero after ca. 24 h.
- Castells, Josep,Lopez-Calahorra, Francisco,Geijo, Fernando
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p. 197 - 208
(2007/10/02)
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