Efficient autocatalytic oximation of bio-based 2,5-diformylfuran with aqueous hydroxylamine under mild conditions†
2,5-Diformylfuran dioxime (DFFD), a rigid bio-based material, is a promising precursor for the manufacturing of advanced functional polymers. An acid autocatalytic oximation of bio-based 2,5-diformylfuran (DFF) initiated with 0.10 wt% HCl in 50 wt% aqueous hydroxylamine (AHA) at 30 °C yielded more than 99% DFFD within 5 min. The utilization efficiency of AHA and the conversion of DFF were 93% and 100%, respectively, through a stepwise AHA feeding strategy. The produced DFFD was easily separated at the kilogram scale by simple filtration, as DFFD was insoluble in water. During the reaction, the pH decreased continually from 6.0 to 2.0 along with the rapid generation of DFFD, which provided enough H+ to efficiently autocatalyse the oximation. Compared with hydroxylamine hydrochloride, AHA was much more efficient, and the generation of waste salts and wastewater decreased by 99.94% and 25%, respectively. Hence, we provide an efficient and clean DFFD production route, which is promising for the green utilization of bio-based furanic compounds.