# Stable and Water-Tolerant Deep Eutectic Solvent from Biomass-Derived 5‑Hydroxymethylfurfural (HMF) and Levulinic Acid

## TL;DR

This paper introduces a stable, water-tolerant deep eutectic solvent made from HMF and levulinic acid, which can improve biomass processing efficiency.

## Contribution

The study demonstrates a novel, stable deep eutectic solvent from HMF and levulinic acid that functions well in the presence of water.

## Key findings

- HMF and levulinic acid form a stable liquid phase with eutectic composition at x_HMF = 0.39.
- The solvent remains functional with low water content and enhances HMF extraction from biomass.
- Hydrogen bonding between HMF and levulinic acid is key to the solvent's stability and performance.

## Abstract

The development of
greener extraction systems is essential to improving
the sustainability of biomass valorization processes. Here we report
that 5-hydroxymethylfurfural (HMF) and levulinic acid (LEV)two
bioderived platform molecules often coproduced in biomass processingspontaneously
form a stable liquid phase over a broad compositional range. Differential
scanning calorimetry (DSC) and thermodynamic modeling reveal a eutectic
composition near x
HMF = 0.39 with a melting
temperature of 258 K and significant negative deviation from ideal
behavior. The mixture remains liquid across a wide compositional range
even in the presence of low water content (0.3–1.0 wt %), exhibiting
deep eutectic solvent (DES)-like behavior. Structural and dynamic
analyses using DSC, NMR spectroscopy, molecular dynamics (MD) and
density functional theory (DFT) calculations uncover a nonideal mixing
regime driven by the network of HMF-LEV hydrogen bonding. Notably,
water does not disrupt the HMF-LEV network but enhances its structuration
at the eutectic composition by moderating LEV-LEV interactions and
enabling more favorable HMF-LEV hydrogen bonding. This work shows
that the liquid HMF-LEV phase can be generated in situ within a heterogeneous biomass surrogate, enabling substantially
higher HMF extraction efficiencies than conventional solvents and
eliminating the need for additional organic extractants. This provides
a proof of concept for a solvent-minimized route to HMF recovery,
indicating the HMF-LEV system as a promising, bioderived liquid platform
with potential for integration into future resource-efficient biorefinery
schemes.