An efficient approach to produce 2,5‐diformylfuran from 5‐hydroxymethylfurfural using air as oxidant

BACKGROUND 2,5‐Diformylfuran (DFF) is a versatile bio‐derived platform chemical. Multiple catalytic systems including homogeneous and heterogeneous catalysts have been studied for the oxidation of 5‐hydroxymethylfurfural (HMF) to DFF, but a more efficient and economical approach to produce DFF via HMF remains to be developed. RESULTS This study provides a practical approach to oxidizing HMF to DFF using Fe(NO 3 ) 3 /Cu(NO 3 ) 2 as catalysts and air as oxidant with the assistance of K 2 S 2 O 8 . The typical oxidation of HMF to DFF was conducted under conditions of 4 wt% catalyst, 80 °C and 3 h, achieving an excellent DFF yield of over 99%. CONCLUSION In this oxidation reaction, Fe(NO 3 ) 3 played a crucial catalytic role by the redox cycle of Fe(III) and Fe(II), while Cu(NO 3 ) 2 functioned as a co‐catalyst to promote the redox cycle of Fe(II) and Fe(III) by the redox cycle of Cu(II) and Cu(I) with the assistance of oxygen. Meanwhile, NO 2 released from the decomposition of Fe(NO 3 ) 3 during the redox cycle of Fe(II) and Fe(III) also participated in the oxidation of Fe(II) to Fe(III) by the redox cycle of NO 2 and NO with the assistance of oxygen. Noteworthily, K 2 S 2 O 8 provided an essential acidity to the oxidation of HMF to DFF through its decomposition product SO 3 . All these factors together ensured the efficient conversion of HMF and high selectivity of DFF. © 2019 Society of Chemical Industry