Bio-based green solvent for metal-free aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfural over nitric acid-modified starch
Mei Hong, Shuangyan Wu, Himanshu Sekhar Jena, Jiatong Li, Linfei Ding, Jing Wang, Lifen Wei, Zhi Ling, Kun Li, Shifa Wang
Abstract
The non-toxic biologic material of expanded corn starch (ECS)-supported nitric acid (ECS-HNO3 and ECS-NH2-HNO3) has been prepared via simple procedures. Both the materials are used as heterogeneous catalysts for the selective aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) with an up to 98% yield in γ-butyrolactone (GBL, a bio-based green solvent) containing as little as 10% (v/v) acetic acid (AcOH) after less than 5 h under ambient pressure of dioxygen at 50 oC. The ECS-NH2-HNO3 proved to be more stable than ECS-HNO3 and was repeatedly used five times with almost no change in its catalytic performance.