Molecular simulations of understanding the structure and separation thermodynamics of 5-Hydroxymethylfurfural from 1-Butyl-3-Methyl imidazolium tetrafluoroborate

Abstract

The furfural-based compounds derived from biomass is proven to be reducing greenhouse gas emissions for sustainable chemical processes. 5-hydroxymethylfurfural (5-HMF) is a bio-renewable material that can serve as a significant platform chemical to produce biofuels, green polymers, solvents, etc. Ionic liquids (ILs) have shown promising reaction media to produce 5-HMF from glucose and fructose. However, there is a substantial challenge in separating the 5-HMF from the ILs. In this paper, we use an organic solvent tetrahydrofuran (THF) to understand the molecular level properties of 5-HMF from 1-butyl-3-methyl imidazolium tetra-fluoroborate [BMIM]+[BF4]− using all-atom molecular dynamics simulations. We have analyzed various intermolecular structures, and dynamic and separation thermodynamic properties. Our results show that with an increase in 5-HMF concentration, we observe a favorable intermolecular interaction between 5-HMF and THF compared to the interactions between 5-HMF and [BMIM]+. The 5-HMF presents the dominant intermolecular interactions with cations compared to the anions. The self-diffusion coefficient of 5-HMF shows a decrease in THF and an increase in [BMIM]+[BF4]− with the rise in 5-HMF concentration. The solvation free energy (ΔGsolv) values of 5-HMF in both IL and THF show less negative value with an increase in 5-HMF concentration. The transfer free energy (ΔGtransfer) of 5-HMF (from IL to THF) shows less positive values with an increase in 5-HMF concentration. Overall results presented in this work are promising for understanding the complex interactions between furfural-based compounds and ILs.