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

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 degrees 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.