## 3 Results and Discussion
### Recovery and Reusability of [DBDIm]I in Glucose Conversion  
The HMF, LA, and FA were easily separated from the aqueous phase due to their difference in polarity, which is significantly different from [DBDIm]I. The efficient extraction of HMF requires a suitable solvent that should have low miscibility with water and lead to a high partition coefficient for each compound [24; 43; 46; 50]. Therefore, [DBDIm]I can be used as a potential solvent. The conversion products in the [DBDIm]I phase can be easily separated by extracting in demineralized water. This advantage has led to the recycling and reuse of [DBDIm]I several times. Thus, the recovered [DBDIm]I can be reapplied for the next glucose conversion to the HMF process. The extraction of products was carried out using the mixtures of toluene and water (4:1, v/v) by liquid-liquid extraction to separate the HMF from LA and FA. After washing twice, the recycled [DBDIm]I was further used in the conversion process of 0.5 g of glucose with or without the addition of 0.5 mL 1 M H\({}_{2}\)SO\({}_{4}\) at 100 \({}^{\circ}\)C for 2 h in an oven, for up to five cycles. The results are shown in Figure 5. The %mole yield trend of the glucose conversion products (HMF, LA, and FA) in the presence of H\({}_{2}\)SO\({}_{4}\) decreased in each subsequent cycle, resulting in lower yields of products after the fifth cycle: 77.2% HMF, 14.0% LA, and 2.8% FA. Similarly, the use of recycled IL for glucose conversion in the absence of H\({}_{2}\)SO\({}_{4}\) produced a lower %mole yield of HMF, LA, and FA, which were 48.2%, 8.8%, and 1.7%, respectively.  
Figure 4: Proposed mechanism of glucose dehydration in [DBDIm]I as a solvent in the presence of a Bronsted acid catalyst. Note: (**a**) hydrolyze glucose with acid; (**b**) ring opening of glucose (dehydration); (**c**) closing pentacyclic; (**d**) de-carbonion; (**e**) oxidation of anomeric carbon; (**f**) HMF.  
This study showed that [DBDIm]I has potential as a solvent and catalyst for glucose conversion. The yields of HMF, LA, and FA decreased during each cycle because [DBDIm]I was consumed during the reaction. The recycled [DBDIm]I supported by H\({}_{2}\)SO\({}_{4}\) presented a relatively good performance, with an HMF yield higher than 70.0%, for up to five cycles, as shown in Figure 5. [PERSON] et al. [16] showed that the HMF from fructose conversion supported by metal halides as a Lewis acid was under 70.0% when reacted for 3 h. [PERSON] et al. [14] used [BMIm]Cl and CrCl\({}_{3}\)-AlCl\({}_{3}\) as catalysts in glucose conversion for 2 h at 120 \({}^{\circ}\)C, producing approximately 54.7% HMF. [PERSON] et al. [15] also reported the yield of 31.2% HMF when cellulose was used as a substrate with [EMIm]Cl and ATP-SO\({}_{3}\)H-Cr(III) as catalysts. Our study showed that [DBDIm]I is a more effective medium due to its recyclability and its capability to retain its catalytic property in glucose conversion up to the five cycles.  
The use of imidazolium-based IL, such as [DBDIm], has some advantages, such as being environmentally friendly, non-toxic, and easy to be produced on an industrial scale [25; 51; 52; 53]. Other reports showed the use of [BMIm]Cl and [HMim]HSO\({}_{4}\) as eco-friendly Lewis acid imidazolium-based ILs in cellulose conversion, with the addition of a metal ion catalyst, was more effective and efficient compared to other methods [3; 40]. [PERSON] et al. [45] reported that the tetrabutylammonium-chloride (TBAC) and chromium(III) trichloride (CrCl\({}_{3}\)\(\cdot\)6H\({}_{2}\)O) catalysts have significantly accelerated the conversion process  
Figure 5: Results of glucose conversion in recycled [DBDIm]I at 100 \({}^{\circ}\)C for 2 h with H\({}_{2}\)SO\({}_{4}\) (**a**) and without H\({}_{2}\)SO\({}_{4}\) (**b**).  
of cellulose to HMF. However, this ammonium-based IL is more toxic to the environment than the imidazolium-based IL [25; 51; 52; 53]. The present study showed the versatility of [DBDIm]I, which acts as a catalyst and as a solvent, in improving the glucose dehydration to HMF.