Microreactor Process for the Optimized Synthesis of 5‐Hydroxymethylfurfural: A Promising Building Block Obtained by Catalytic Dehydration of Fructose

Abstract

AbstractA continuous microreaction process was set up to analyze and improve the “green” synthesis of 5‐hydroxymethylfurfural (5‐HMF) based on the HCl‐catalyzed dehydration of fructose in pure aqueous solutions. The process conditions were deliberately shifted to high temperatures and pressures (185 °C, 17 bar) and combined with a reduced reaction time of only 1 min to avoid extensive rehydration of the product. 5‐HMF was obtained with 75 % selectivity and 54 % yield at 71 % fructose conversion. In comparison to published data, a 24 % increase in selectivity and a 21 % increase in conversion could be achieved. Moreover, by adding organic co‐solvents and extraction agents to the reaction system, both 5‐HMF selectivity and yield could be further enhanced to 85 and 82 %, respectively. However, the use of additional organic solvents cannot be considered as a “green” process anymore.