An efficient and practical approach for the continuous‐flow synthesis of 5‐hydroxymethylfurfural from carbohydrates using an acidic ionic liquid.

BACKGROUND: Flow chemistry is becoming an essential technique in organic synthesis. This trend is expected to continue and broaden in scope and complexity. This miniaturized protocol that includes microreactors enables excellent heat transfer, low solvent wastage, shorter reaction times, higher productivity and higher space–time yields. RESULTS: In this study, we synthesized four ionic liquids and applied them as catalysts for the selective preparation of 5‐hydroxymethylfurfural (5‐HMF) from fructose using the continuous flow system. The effects of reaction time and temperature, catalyst loading, solvent and substrates for carbohydrate conversion to 5‐HMF have been carefully investigated, and 5‐HMF yields were determined by high‐performance liquid chromatography. CONCLUSION: As a result, 1‐(4‐sulfobutyl)pyridinium iron(III) chloride gave 71% yield of 5‐HMF for 30 min. The results of this research demonstrate that this approach is not only straightforward in design but also rapid and convenient in operation, and it has the potential to be carried out on a massive scale. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]