Mechanisms and Energetics for Acid Catalyzed β-D-Glucose Conversion to 5-Hydroxymethylfurfurl

Car-Parrinello based ab initio molecular dynamics (CPMD) coupled with metadynamics (MTD) simulations were carried out to investigate the mechanism and energetics for acid catalyzed β-D-glucose conversion to 5−Hydroxymethylfurfurl (HMF) in water, a critical intermediate for biomass conversion to biofuels. It was found that protonation of the C2−OH on glucose, the breakage of the C2−O2 bond and the formation of the C2−O5 bond is the critical rate-limiting step for the direct glucose conversion to HMF without going through fructose, contrary to the wide−spread assumption that fructose is the main intermediate for glucose conversion to HMF. The calculated reaction barrier of 30−35 kcal /mol appears to be solvent induced and is in excellent agreement with experimental observations.