High-Efficiency Synthesis of 5-Hydroxymethylfurfural from Fructose over Highly Sulfonated Organocatalyst

The high-efficiency conversion of fructose to 5-hydroxymethylfurfural (HMF) with approving yields is challenging in biorefinery. In this work, we develop an efficient method of preparing HMF from fructose catalyzed by a highly sulfonated polyaniline-based organocatalyst (S-A-PAN-H). We show that the novel organocatalyst is mainly Lewis acidic with a total acid density of 2.3 mmol.g(-1) with lower acidic strength. For converting low-concentration fructose (45.0 g.L-1), a maximum HMF yield of 88.8% has been achieved in dimethyl sulfoxide (DMSO) or low-boiling 1,4-dioxane/water within 40-45 min, wherein the side reaction of HMF rehydration could be completely restrained. Notably, the S-A-PAN-H organocatalyst exhibits excellent catalytic performance and good recyclability for converting high-concentration fructose (100.0-400.0 g.L-1) to HMF, thereby representing an effective strategy for HMF production.