Systematic Identification of Solvents Optimal for the Extraction of 5‑Hydroxymethylfurfural from Aqueous Reactive Solutions

To ensure a high efficiency of 5-hydroxymethylfurfural (HMF) synthesis, improved solvents for the extraction of HMF from a reactive aqueous solution were identified using the predictive thermodynamic model COSMO-RS. Utilizing COSMO-RS as a basis for a systematic solvent selection has the advantage of potentially saving significant time and effort by computationally screening several thousand possible solvents. Factors including temperature, concentration, and fructose addition were used for experimental validation of the predictive power of COSMO-RS. Continuous extraction experiments confirmed also kinetics and phase separation to be important for technical implementation. COSMO-RS predicted o-propylphenol and o-isopropylphenol to have partition coefficients as high as 10.02 and 9.82, which are roughly five times higher than the partition coefficient of the previously known, most effective solvent: 2-methyltetrahydrofuran (PHMF = 2). Therefore, the identification of o-propylphenol and o-isopropylphenol as improved solvents constitutes a significant efficiency improvement for the extraction, and by extension for the entire HMF synthesis.