Article pubs.acs.org/IECR
Autocatalytic Production of 5‑Hydroxymethylfurfural from FructoseBased Carbohydrates in a Biphasic System and Its Purification Hao Ma, Furong Wang, Yinghao Yu, Lefu Wang, and Xuehui Li* School of Chemistry and Chemical Engineering, Pulp & Paper Engineering State Key Laboratory of China, South China University of Technology, Guangzhou 510640, P. R. China S Supporting Information *
ABSTRACT: An efficient autocatalytic process for the production of 5-hydroxymethylfurfural (HMF) from fructose-based carbohydrates has been investigated without the addition of any external catalysts in a methyl isobutyl ketone/water biphasic system, leading to elevated HMF yield through continuous extraction of HMF from an aqueous solution. The results show that both the reaction temperature and time have significant effects on fructose conversion and HMF yield; 96.8% of fructose can be converted into 73.6% of HMF with a small amount of levulinic acid and formic acid formed at a point of compromise between the reaction temperature and time (160 °C for 2 h). In addition, this autocatalytic system is suitable for other fructose-based feedstocks, such as sucrose and inulin, to achieve acceptable HMF yield. Moreover, a simple and efficient purification strategy for as-prepared HMF, viz., the NaOH neutralization method, has also been tested, achieving more than 99% of HMF recovery with more than 98% of purity correspondingly. product with up to 84.9% yield.12 Moreover, our previous work also provided a catalyst-free route in the functionalized IL 3-(2chloroethyl)-1-methylimidazolium chloride ([ClC2mim]Cl) to achieve 76% yield of isolated HMF.13 However, these contributions still encountered some problems in terms of environmental toxicity, high expensive IL dosage for fructose dissolution, or a difficult product purification process from the high-boiling-point organic solvents. Compared with the solvents mentioned above, the application of cheaper, safer, and more environmentally benign water (H2O) as a reaction medium has attracted considerable attention over recent decades.14−16 Moreover, it was reported that sugars, such as fructose, sucrose, and glucose, can be converted into HMF in H2O with interesting yields in the absence of catalyst under elevated reaction temperatures (>180 °C).17−20 Possible autocatalysis of sugars caused by the formed levulinic acid (LA) and FA is an acceptable mechanism for the transformation, which has been investigated intensively by Ranoux et al.21 Frustratingly, the aqueous medium is still restricted due to the drastic rehydration of HMF into LA and FA or the condensation of HMF into soluble or insoluble byproducts (humins), resulting in poor product yield (
