Mechanistic Insights into the Brønsted Acid-Catalyzed Dehydration of β‑d‑Glucose to 5‑Hydroxymethylfurfural under Ambient and Subcritical Conditions

Conversion of biomass to fuels and other useful chemicals is one of the most active fields of research today. In this respect, dehydration of glucose to 5-hydroxymethylfurfural (HMF) has gained much attention recently. Carrying out this reaction with high efficiency in green solvents, especially in water, is a major challenge to overcome. In spite of several years of experimental and computational studies, the detailed mechanism of the conversion of glucose to HMF remains elusive. Detailed mechanistic understanding of this reaction can aid in the development of novel catalysts for carrying out the reaction in water. In addition, understanding the effects of reaction conditions such as temperature and pressure on the mechanism and kinetics of this reaction could provide additional information to optimize thermodynamic conditions for HMF production on an industrial scale, and thus, we study that here in detail. Our study is based on computational modeling of this chemical reaction in explicit water under different thermodynamic conditions using molecular dynamics simulations at the level of density functional theory. This work addresses the long-standing open questions on the mechanism and the effects of the thermodynamic conditions. Our simulations shed light on the critical steps for which a catalyst could be designed to improve the efficiency.