Conversion of Cellulose to 5-Hydroxymethylfurfural in Water-Tetrahydrofuran and Byproducts Identification

Conversion of cellulose into platform chemical 5-hydroxymethylfurfural (HMF) in water-tetrahydrofuran (THF) co-solvents under acidic condition was studied. 38.6% of HMF was obtained with low cellulose concentration of 2.4wt%, but levulinic acid (LA) and solid humins became the main products with high cellulose concentration. The soluble byproducts were analyzed by high performance liquid chromatography/multiple stage tandem mass spec-trometry, and chemicals with formula of C₉H₁₆O₄、 C₁₀H₁₄O₄、 C₁₁H₁₂O₄、C₁₂H₁₀O₅ and C₁₂H₁₆O₈ were detected. THF could participate in the reaction via ring-opening into 1,4-butanediol followed by esterification with LA into C₉H₁₆O₄ or etherification with HMF into C₁₀H₁₄O₄. C₁₁H₁₂O₄ was formed by esterification of HMF with LA, C₁₂H₁₀O₅ was formed by self-etherification of HMF, while C₁₂H₁₆O₈ was formed by acetalization of HMF with glucose. Self-etherification of HMF and etherification of HMF with 1,4-butanediol were identified as two main side reactions.