continuously, which would produce more HMF and reduce
the by-products. The separation of the product was also easy
because the upper phase consisted only of the solvent and the
product. A yield of 64% was achieved in the biphasic system with
ChoCl/oxalic acid as the solvent and AcOEt as the extraction
solvent, which is considerably higher than that in the neat IL
was recycled 6 times. We believe that this highly efficient and
greener route has great potential for application.
Acknowledgements
We thank the National Natural Science Foundation of
China (20533010) and the Chinese Academy of Sciences
(
Table 1, entries 1 and 9).
(KJCX2.YW.H16).
Reusability of the IL
The recycling of ChoCl/oxalic acid in the biphasic system was
investigated. The conditions were the same as those of entry 9 in
Table 1. After reaction, there were two phases in the reactor. The
upper phase consisted of AcOEt and HMF and the other phase
was rich in IL. After separation of the two phases, the product
in the IL was further extracted using fresh AcOEt and the IL
was reused directly. The results of recycling the IL are presented
in Fig. 3. It should be indicated that the activity of the recycled
IL was still very high after being used six times.
References
1
(a) M. St o¨ cker, Angew. Chem., Int. Ed., 2008, 47, 9200–9211; (b) A.
Corma, S. Iborra and A. Velty, Chem. Rev., 2007, 107, 2411–
2
502; (c) J. N. Chheda, G. W. Huber and J. A. Dumesic, Angew.
Chem., Int. Ed., 2007, 46, 7164–7183; (d) T. Werpy and G. Petersen,
Top Value Added Chemicals from Biomass, U. S. Department
of Energy report No. DOE/GO-102004-1992, Golden, CO, 2004
(www.Osti.gov/bridge).
2
3
(a) Y. R o´ man-Leshkov, C. J. Barrett, Z. Y. Liu and J. A. Dumesic,
Nature, 2007, 447, 982–985; (b) Y. R o´ man-Leshkov, J. N. Chheda
and J. A. Dumesic, Science, 2006, 312, 1933–1937.
H. B. Zhao, J. E. Holladay, H. Brown and Z. C. Zhang, Science,
2
007, 316, 1597–1600.
4
5
M. Biker, J. Hirth and H. Vogel, Green Chem., 2003, 5, 280–284.
G. W. Huber, J. N. Chheda, C. J. Barrett and J. A. Dumesic, Science,
2
005, 308, 1446–1450.
M. J. Antal, Jr., W. S. L. Mok and G. N. Richards, Carbohydr. Res.,
990, 109, 91–109.
Y. Nakamura and S. Morikawa, Bull. Chem. Soc. Jpn., 1980, 53,
705–3706.
6
7
8
1
3
(a) K. Seri, Y. Inoue and H. Ishida, Bull. Chem. Soc. Jpn., 2001, 74,
1
2
145–1150; (b) K. Seri, Y. Inoue and H. Ishida, Chem. Lett., 2000,
2–23.
9
(a) F. S. Asghari and H. Yoshida, Ind. Eng. Chem. Res., 2006, 45,
2
163–2173; (b) F. S. Asghari and H. Yoshida, Cabohydr. Res., 2006,
41, 2379–2387.
3
1
1
1
0 J. N. Chheda, Y. R o´ man-Leshkov and J. A. Dumesic, Green Chem.,
2
007, 9, 342–350.
1 C. Moreau, R. Durand, S. Razigade, J. Duhamet, P. Faugeras, P.
Rivalier, P. Ros and G. Avignon, Appl. Catal., A, 1996, 145, 211–224.
2 M. Nagamori and T. Funazukuri, J. Chem. Technol. Biotechnol.,
2004, 79, 229–233.
Fig. 3 Results of recycling ChoCl/oxalic acid in the ChoCl/oxalic
acid/AcOEt biphasic reaction system. The conditions were the same as
those of entry 9 in Table 1.
13 A. K. Gupta and I. S. Bhatia, Phytochemistry, 1982, 21, 1249–1253.
1
1
4 A. K. Gupta and N. Kaur, Curr. Sci., 2007, 93, 595–596.
5 (a) J. R. Rocha, R. Catana, B. S. Ferreira, J. M. S. Cabral and P.
Fernandes, Food Chem., 2006, 95, 77–82; (b) R. S. Singh, R. Dhaliwal
and M. Puri, J. Ind. Microbiol. Biotechnol., 2008, 35, 777–782; (c) C.
Blecker, C. Fougnies, J. C. V. Herck, J.-P. Chevaller and M. Paquot,
J. Agric. Food Chem., 2002, 50, 1602–1607.
Our experiment showed that the accumulated residue (mainly
di-D-fructose dianhydrides) and the IL in the IL phase could
be separated by extraction using ethanol because the IL is
soluble in ethanol, while the residue is not soluble in ethanol
at room temperature. At room temperature, when 2 mL of
ethanol were added into the IL phase which was recycled 6 times,
the IL dissolved in the ethanol and the accumulated residue
precipitated from the ethanol solution. Then, the precipitate was
removed by filtration and the IL was refreshed after removing
the ethanol from the filtrate by distillation.
16 (a) F. Benvenuti, C. Carlini, P. Patrono, A. M. R. Galletti, G. Sbrana,
M. A. Massucci and P. Galli, Appl. Catal., A, 2000, 193, 147–153;
(
b) C. Carlini, M. Giuttari, A. M. R. Galletti, G. Sbrana, T. Armaroli
and G. Busca, Appl. Catal., A, 1999, 183, 295–302; (c) C. Carlini, P.
Patrono, A. M. R. Galletti and G. Sbrana, Appl. Catal., A, 2004, 275,
1
11–118.
1
7 (a) P. Wassercheid and T. Welton, in Ionic Liquids in Synthesis, Sec-
ond, Completely Revised and Enlarged Edition, vol. 1, ed. J. S. Wilkes,
P. Wassercheid and T. Welton, WILEY-VCH, Weinheim, 2008, pp.
1–6; (b) P. Wassercheid and W. Keim, Angew. Chem., Int. Ed., 2000,
3
9, 3772–3789.
8 (a) R. D. Rogers and K. R. Seddon, Science, 2003, 302, 792–793;
b) R. D. Rogers and K. R. Seddon, in Ionic Liquids as green solvents:
1
(
Conclusion
process and prospects, ACS, Washington, D. C., 2003.
9 M. Avalos, R. Babiano, P. Cintas, J. L. Jim e´ nez and J. C. Palacios,
Angew. Chem., Int. Ed., 2006, 45, 3904–3098.
0 (a) A. P. Abbott, G. Capper, D. L. Davies, R. K. Rasheed and V.
Tambyrajah, Chem. Commun., 2003, 70–71; (b) A. P. Abbott, D.
Boothby, G. Capper, D. L. Davies and R. K. Rasheed, J. Am. Chem.
Soc., 2004, 126, 9142–9147.
1 (a) S. Q. Hu, Z. F. Zhang, Y. X. Zhou, B. X. Han, H. L. Fang,
W. J. Li, J. L. Song and Y. Xie, Green Chem., 2008, 10, 1280–1283;
(b) R. C. Morales, V. Tambyrajah, P. R. Jenkins, D. L. avies and
1
2
In summary, inulin was efficiently converted to HMF in a one-
pot reaction in ChoCl/oxalic acid or ChoCl/citric acid, which
were prepared from cheap biorenewable materials. Moreover,
the yield of HMF in the AcOEt/ChoCl/oxalic acid biphasic
system was considerably higher. The IL phase could be recycled
directly after removing the AcOEt phase that contained HMF,
and the reduction in the yield was not considerable after the IL
2
8
76 | Green Chem., 2009, 11, 873–877
This journal is © The Royal Society of Chemistry 2009