(329b) From Cyclic to Open Chain Form - Ab Initio Molecular Dynamics Simulation of Glucose Ring Opening Process

Cellulosic biomass represents an abundant renewable resource for the production of bio-based products and biofuels. Both biochemical and liquid phase chemical processing routes generally require conversion of cellulose to monomer glucose as the first step for biofuel production.  Understanding glucose reactivity is critical for biofuel production.

            Several glucose reactions including α-β mutarotation are thought to be initiated by the opening of the pyranose ring structure.  There are considerable debate exist in literature with respect to whether glucose dehydration to form HMF and isomerization to form fructose proceed via the aldose to ketose transformation with a series of open chain forms or via the direct cyclic mechanism converting a pyranose ring to a furanose ring . In order to resolve this controversy, Car-Parrinello molecular dynamics simulations were conducted to investigate the barriers and free energies associated with the ring-opening and ring closing processes catalyzed by the proton in both aqueous solution and DMSO solvent. These results will be compared directly with data for the direct cyclic mechanism obtained earlier.  The implications for glucose reactions will be discussed.