Mechanism of the dehydration of d-fructose to 5-hydroxymethylfurfural in dimethyl sulfoxide at 150 °C: an NMR study

The anomeric composition of d-fructose in dimethyl sulfoxide changes when the solution is heated from room temperature to 150 °C, with a small increase in the α-furanose form at the expense of the β-pyranose tautomer. Additionally, a small amount of α-pyranose form was also observed at 150 °C. A mechanism is proposed for the dehydration of d-fructose to 5-hydroxymethylfurfural in DMSO at 150 °C, where the solvent acts as the catalyst. A key intermediate in the reaction was identified as (4R,5R)-4-hydroxy-5-hydroxymethyl-4,5-dihydrofuran-2-carbaldehyde by using 1H and 13C NMR spectra of the sample during the reaction.

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