(157a) A Novel Method of Producing 2,5-Diformylfuran at High Yields from Glucose

We present a process for converting lignocellulosic biomass-derived glucose into 2,5-diformyl furan, a promising bio-based intermediate for polyethylene furanoate. The route to 2,5-diformylfuran (DFF) is oxidation of 5-hydroxymethylfurfural (HMF), which can be prepared via dehydration of fructose. However, there are two major challenges – 1) Unlike glucose, fructose is not naturally abundant and 2) HMF tends to degrade in presence of water during its isolation.

Our process addresses above limitations and demonstrates an environmentally sustainable and economically viable process for production of DFF, a bio-based intermediate for polymers. First, glucose is isomerized into fructose at quantitative yields using a novel Simultaneous-Isomerization-Reactive-Extraction (SIRE) process. In SIRE process, immobilized GXI enzyme isomerizes glucose into fructose, which is concurrently extracted into an immiscible octanol phase. Aryl boronic acid, added to octanol, facilitates the selective extraction of fructose; and thereby overcomes the isomerization equilibrium. Next, fructose is recovered from organic phase into acidic water (pH = 2) by back-extraction. Later, fructose undergoes acid-catalyzed dehydration reaction (T = 120 °C) into HMF in water and in presence of acetone as homogenous solvent. Solvation of HMF by acetone minimizes its degradation under acidic aqueous environment and achieves high yield of 90%. Later, HMF-rich water-acetone solvent system is contacted with toluene. Addition of non-polar solvent, toluene, creates a biphasic system – 1) HMF-rich organic phase of acetone + toluene, 2) HMF deprived and sugar rich water phase which is recycled. From above organic phase, low-boiling acetone is separated to yield HMF-rich toluene phase. Oxidation of HMF in toluene phase is conducted using reusable metal catalyst (Ru/C) to achieve quantitative yields of 2,5-diformylfuran.

The proposed process offers advantages of near-complete utilization of glucose by overcoming isomerization equilibrium and high-yields of DFF by eliminating isolation of unstable HMF intermediate.