Organic Carbonates: Efficient Extraction Solvents for the Synthesis of HMF in Aqueous Media with Cerium Phosphates as Catalysts

We describe a process for the selective conversion of C-6-polyols into 5-hydroxymethylfurfural (5-HMF) in biphasic systems of organic carbonate/water (OC/W), with cerium(IV) phosphates as catalysts. Different reaction parameters such as the OC/W ratio, catalyst loading, reaction time, and temperature, were investigated for the dehydration of fructose. Under the best reaction conditions, a yield of 67.7% with a selectivity of 93.2% was achieved at 423K after 6h of reaction using [(Ce(PO4)(1.5)(H2O)(H3O)(0.5)(H2O)(0.5))] as the catalyst. A maximum yield of 70% with the same selectivity was achieved after 12h. At the end of the reaction, the catalyst was removed by centrifugation, the organic phase was separated from water and evaporated in vacuo (with solvent recovery), and solid 5-HMF was isolated (purity >99%). The recovery and reuse of the catalyst and the relationship between the structure of the OC and the efficiency of the extraction are discussed. The OC/W system influences the lifetime of the catalysts positively compared to only water.