Technological aspects of fructose conversion to high-purity 5-hydroxymethylfurfural,a versatile platform chemical

Two improved methods for the synthesis of 5-hydroxymethylfurfural by acid-catalyzed dehydration of fructose have been developed. The first one is the synthesis in ionic liquids with continuous removal of water under reduced pressure, and the second is the synthesis in the two-phase system consisting of aqueous NaHSO₄ and methyl isobutyl ketone under atmospheric pressure. Both methods ensure isolation of crystalline 5-hydroxymethylfurfural with high purity and multiple recycling of the catalytic system. The synthesis in ionic liquid is convenient on a laboratory scale. Despite relatively low yield, the two-phase synthesis is preferred for industrial scale-up due to simple isolation and purification procedures combined with efficient regeneration of extractant and the catalytic system.