Green synthesis of furfural from xylose and corn cob biomass

Furfural is a versatile, high-value-added platform molecule that can be produced from five carbon atom (C5) carbohydrates present in lignocellulosic biomass. It has numerous industrial applications in view and has the potential to replace materials derived from fossil resources. Therefore, in this work, the synthesis of furfural from xylose and corn cob biomass was proposed, using p-sulfonic acid calix[4]arene (CX4SO(3)H) as an organocatalyst, a biphasic system (butyl acetate and saturated aqueous solution of NaCl) and a microwave-assisted (MW) method. Thus, furfural was obtained in 77.0% yield from xylose, by MW at 160 degrees C for 10 min and using 1.0 mol% of CX4SO(3)H (5 wt%). These same conditions were used for the synthesis of furfural from arabinose, and a yield of 40.5% was obtained. When using corn cob biomass as a substrate, furfural was obtained with 56% yield, by mass, by MW at 160 degrees C for 60 min and using 12.5 wt% of CX4SO(3)H. In addition to the satisfactory yields, the methodology developed in this work has other advantages, such as obtaining furfural directly from renewable raw materials, saving carbon and generating water as the only by-product, short reaction time, using a recyclable catalytic system (CX4SO(3)H and saturated aqueous NaCl solution), employing a non-corrosive and low-toxicity catalyst and being metal-free. The sum of these characteristics makes the developed process consistent with the principles of green chemistry.