Conversion of carbohydrates into 5‐hydroxymethylfurfural in a green reaction system of CO2‐water‐isopropanol

In this work, a green reaction system of CO₂‐water‐isopropanol was developed for 5‐hydroxymethylfurfural (HMF) production. The conversion of fructose in a CO₂‐water system was first investigated, and the results showed this system could promote the formation of HMF compared to a pure water system. Then, isopropanol was introduced into the CO₂‐water system and the HMF formation became better because the solvent effect of isopropanol increased the tautomeric composition of fructofuranose, which was easy to form HMF. The existence of isopropanol was found to greatly suppress secondary reactions where HMF was converted to levulinic acid and insoluble humin. Meanwhile, the effects of reaction parameters on the conversion of fructose to HMF in the CO₂‐water‐isopropanol system were analyzed, and a high HMF yield of 67.14% was obtained. Finally, to further illustrate the merits of CO₂‐water‐isopropanol system, productions of HMF from other carbohydrates were tested and satisfactory yields were achieved. © 2016 American Institute of Chemical Engineers AIChE J, 63: 257–265, 2017