Ab initio molecular dynamics simulations of β-d-glucose and β-d-xylose degradation mechanisms in acidic aqueous solution

Liquid‐Phase Catalytic Processing of Biomass‐Derived Oxygenated Hydrocarbons to Fuels and Chemicals

“…Dehydration of hexoses has been studied in water, organic solvents, biphasic systems, ionic liquids, and near-or supercritical water, using a variety of catalysts such as mineral and organic acids, organocatalysts, salts, and solid acid catalysts such as ion-exchange resins [23] and zeolites [24] in the temperature range of 370-470 K. Although evidence exists that supports both the open-chain and the cyclic fructofuransyl intermediate pathways (Scheme 1), it is clear that the reaction intermediates and the HMF product degrade by means of various processes. [24][25][26][27] Similarly, glycerol can be dehydrated to acrolein, a polymer intermediate used in the production of polyesters such as SORONA. Ott et al have shown promising results using sub-and supercritical water with zinc sulfate salts as catalysts to achieve yields of acrolein of up to 80 %; however, corrosion induced by water and salt at these conditions necessitates the use of expensive corrosionresistant materials for the reaction.…”

“…[63] Previous studies suggested that HMF formation can take place through an open-chain 1,2-enediol mechanism or through fructofuranosyl intermediates. [24,27,64] However, Antal et al showed that the formation of HMF from fructose proceeds via cyclic intermediates, providing evidence such as 1) facile conversion of 2,5-anhydro-dmannose (an intermediate enol in cyclic mechanism) to HMF; 2) facile formation of HMF from the fructose part of sucrose; and 3) lack of carbon-deuterium bond formation in HMF owing to keto-enol tautomerism in the open-chain mechanism when the reaction is carried out in D 2 O. [25,26,65] Similarly, results from theoretical calculations reinforce the conclusion that cyclic reaction pathways are dominant for HMF formation from glucose and xylose.…”

“…[25,26,65] Similarly, results from theoretical calculations reinforce the conclusion that cyclic reaction pathways are dominant for HMF formation from glucose and xylose. [27] While selectivity in the presence of water is low, high yields (> 90 %) can be achieved in aprotic solvents such as DMSO. [66] Previous studies suggest that fructose is predominantly present in the furanose form in aprotic solvents such as DMSO and at higher temperatures, when compared to the dominant b-pyranose form in pure water.…”

Optimizing Dilute-acid Hydrolysis (DACH) of Distillers Grains and Ethanol Fermentation

“…Thus, sulfuric acid is more efficient, because sulfuric acid has an extra hydrogen ion which creates more acidic medium to promote hydrolysis of the acid-sensitive 1,4-glycosidic linkages. As explained by Qian et al, the hydrogen ion concentration is significant for RS release [19].…”

Ab initio and semi-empirical Molecular Dynamics simulations of chemical reactions in isolated molecules and in clusters

“…In due course, many applications to chemical processes were made. Thus, CPMD has been applied to a large variety of chemical reactions, including classical organic chemistry reactions, 5 proton transfer reactions, 6,7 reactions on metal surfaces, 8 in aqueous solutions, 9 and organometallic catalysis, 10 to name but a few. Likewise, BOMD has been applied to many chemical processes.…”