Sulfonic acid functionalized dendrimer-grafted cellulose as a solid acid catalyst for the high-yield and green production of 5-hydroxymethylfurfural

Abstract

An efficient heterogeneous acid catalyst was prepared via the growth of a thiol-functionalized third-generation dendrimer on the surface of cellulose employing thiol–ene click chemistry, followed by the formation of sulfonic acid groups via the oxidation of thiol groups. X-ray photoelectron spectroscopy confirmed the complete oxidation of the thiol groups to sulfonic acid groups utilizing H₂O₂ as an oxidant. The synthesized catalyst was studied for its ability to catalyze the conversion of fructose to 5-hydroxymethylfurfural (5-HMF). The effects of different factors on the yield of 5-HMF production were investigated. Over 96% of 5-HMF was achieved from fructose at 110 °C for 45 min in a biphasic acetone:water (2 : 1) medium. The excellent activity of this catalyst could be ascribed to the existence of a dendritic structure, which makes acidic active sites easily accessible. This catalytic system can also be used for efficiently transforming other carbohydrates to 5-HMF. After a fifth cycle of the dehydration of fructose, the catalyst exhibited no remarkable change in its catalytic activity and structure, demonstrating its high stability and recyclability.