Biphasic Production of 5‐hydroxymethylfurfural (HMF) in a Recyclable Deep Eutectic Solvent‐based System Catalyzed by H4SiW12O40

Abstract The reaction with in situ extraction to yield 5‐hydroxymethylfurfural (HMF) from d ‐fructose (Fru) was investigated using a biphasic system based on a self‐consuming deep eutectic solvent (DES) as reaction phase. The significance of choline chloride (ChCl), a cost‐effective and safe quaternary ammonium salt, was evident in enhancing HMF yield through fructose dehydration and concurrently suppressing side reactions. The DES system demonstrated fast reactions with high selecivities and recyclability across five cycles. The observed decline in H 4 SiW 12 O 40 activity, primarily due to proton leaching, was successfully restored with the addition of HCl. Furthermore, ChCl exhibited ease of recrystallization in the presence of acetonitrile. This research proposes an environmentally friendlier approach for HMF production through a reusable‐biphasic process. The presented reaction system suppresses completely the formation of levulinic and formic acid leading to HMF yields of up to 84 % of selectivities of up to 88 % after 30 minutes at 80 °C. The system was recycled over 16 runs and after an initial slight loss of activity the system in the run 0–5, run 6–15 has shown a constant HMF output as in the first recycling run.