Triphenyl Phosphate Catalyst for Efficient Dehydration of Carbohydrates to 5-Hydroxymethylfurfural

Abstract

5-Hydroxymethylfurfural (5-HMF) is recognized as a versatile renewable feedstock with significant potential for the synthesis of a range of valuable chemicals. It can be converted to furan-2,5-dicarboxylic acid, levulinic acid, 2,5-diformylfuran, and 2,5-dimethylfuran. They are used in the production of fuels, polymers, pharmaceuticals, heat-resistant materials, macrocycles, and as active ingredients in nutraceuticals and biodiesel. In this study, we developed an efficient carbohydrate dehydration protocol for the synthesis of 5-HMF using triphenyl phosphate as a catalyst. The catalyst used showed excellent activity, yielding 88% of 5-HMF from fructose at 100 °C in a dimethyl sulfoxide solvent. After the reaction, the catalyst was recovered by extraction with toluene, while 70% of the 5-HMF product was successfully extracted to tetrahydrofuran using a saturated sodium chloride (NaCl) solution. This methodology was also applied to a variety of other carbohydrates, including sucrose, maltose, and xylose, resulting in the formation of both C6 and C5 furan compounds (5-HMF and furfural) with yields ranging from 6 to 88%. With the addition of NaCl as an external additive (solvating agent), a 56% yield of 5-HMF was obtained with the glucose substrate at 160 °C.