Full Papers
Synthesis of [CH3C2PhC2Phim]Cl IL 5
Experimental Section
2-Methylimidazole (0.122 mol, 10 g) and NaOH (0.122 mol, 4.87 g)
were stirred at 1508C for 5 h. The resulting salt (0.067 mol, 7.015 g)
and (2-chloroethyl)benzene (0.135 mol, 19 g) were stirred at 808C
for 48 h. The resulting IL was washed with diethyl ether (3ꢃ10 mL)
and dried under vacuum (yield=90%). 1H NMR (400 MHz, CDCl3,
258C): d=7.62 (s, 1H), 7.3–7.37 (m, 5H), 4.48 (t, J=6 Hz, 2H), 3.11
(t, J=6 Hz, 2H), 1.93 ppm (s, 1H), 13C NMR (CDCl3, 258C): d=143.7,
136.2, 129.1, 128.8, 127.7, 121.9, 50.4, 36.3, 9.4 ppm. ESI-MS (m/z)
291.19 [cation]+. Elemental analysis (%) for C20H23ClN2 (299.13):
calcd. C 73.49, H 7.09, N 8.57; found: C 73.29, H 7.01, N 8.29.
All starting materials including IL 6 were obtained from commer-
cial sources and used as received. [C2OHmim]Cl, IL 1 and IL 7–IL
11 were prepared using literature procedures.[8b,34] Electrospray ion-
ization mass spectra (ESI-MS) were recorded on a ThermoFinnigan
LCQ Deca XP Plus quadrupole ion trap instrument in positive ion
mode.[35] NMR spectra were recorded on a Bruker DMX 400 instru-
ment. Elemental analysis was performed at the Institute of Chemi-
cal Sciences and Engineering, Ecole Polytechnique Fꢂdꢂrale de Lau-
sanne.
Conversion of glucose to HMF
Ball milling pretreatment of cellulose
In
a
typical reaction, glucose (0.28 mmol, 50 mg), CrCl2
Microcrystalline cellulose (1 g) was loaded in a ball mill (Retsch MM
400) equipped with a steel jar (10 mL) and two steel balls (12 mm
diameter) and operated at 30 Hz for 24 h. FTIR spectra of micro-
crystalline and ball-milled cellulose were recorded using a Per-
kinElmer FTIR 2000 spectrometer. For each spectrum, 16 scans
(0.019 mmol, 2.3 mg,), [C2OHmim]Cl (450 mg), and a second IL
(50 mg) were placed in a glass vial. The vial was sealed and the re-
action mixture was then heated to 1008C for the required time.
After reaction the mixture was cooled to RT and the mixture dilut-
ed with water and methanol (4:1, 25 mL) for analysis.
were averaged from 4500 to 500 cmÀ1
.
Dehydration of starch
Synthesis of IL 2
In a typical reaction starch (50 mg), CrCl2 (16 mg), IL [C2OHmim]Cl
(900 mg), IL 1 (100 mg) or IL 4 (100 g) were placed in a glass vial.
The vial was sealed and the reaction mixture was heated to 1408C
for 4 h. After reaction the mixture was cooled to RT and diluted
with water and methanol (3:1, 10 mL) for analysis.
1-Methylimidazole (0.1 mol, 8.2 g) and (2-chloroethyl)benzene (0.1
mol, 14.1 g) were stirred at 808C for 48 h. The resulting IL was
washed with diethyl ether (3ꢃ10 mL) and dried under vacuum
(yield=90%). 1H NMR (400 MHz, DMSO, 258C): d=9.31 (s, 1H),
7.80 (s, 1H), 7.72 (s, 1H), 7.24–7.33 (m, 5H), 4.46 (t, J=8 Hz, 2H),
3.84 (s, 3H), 3.15 ppm (t, J=8 Hz, 2H), 13C NMR (DMSO, 258C): d=
137.4, 137.2, 129.2, 129, 127.3, 123.9, 122.8, 50.1, 36.2, 35.9 ppm.
ESI-MS (m/z) 187.12 [cation]+. Elemental analysis (%) for C12H15ClN2
(222.09): calcd. C 64.72, H 6.79, N 12.58; found: C 64.73, H 6.74, N
11.48.
Conversion of cellulose to HMF
In a typical reaction cellulose (100 mg), CrCl2 (10 mg), [C2OHmim]Cl
(900 mg), IL 1 (100 mg) or IL 4 (100 mg), and the acidic IL (11 mg)
were placed in a glass vial. The vial was sealed and the reaction
mixture was then heated to 1408C for the desired time. After reac-
tion the mixture was cooled to RT and diluted with water and
methanol (4:1, 25 mL) for further analysis. When necessary, MIBK or
DME (6 mL) was added to the reaction vessel. After 80 min the or-
ganic solvent (upper layer) was removed with a syringe and anoth-
er 6 mL of solvent added. At the end of the reaction the mixture
was cooled to RT, the phases were combined and diluted with
water and methanol (4:1, 25 mL) for MIBK or water (for DME) for
Synthesis of IL 3
IL 3 was prepared with the same method as IL 2 using 1,2-dime-
thylimidazole (1 equiv.) and (2-chloroethyl)benzene (1 equiv.) as
starting materials. H NMR (400 MHz, CDCl3, 258C): d=7.86 (s, 1H),
7.72 (s, 1H), 7.04–7.28 (m, 5H), 4.53 (t, J=8 Hz, 2H), 3.91 (s, 3H),
3.15 (t, J=8 Hz, 2H), 2.26 ppm (s, 3H), 13C NMR (CDCl3, 258C): d=
143.9, 136.3, 129.1, 128.9, 127.6, 123.3, 121.5, 50.4, 36.6, 35.8,
9.8 ppm. ESI-MS (m/z) 201.14 [cation]+. Elemental analysis (%) for
C13H17ClN2 (236.11): calcd. C 65.95, H 7.24, N 11.83; found: C 65.87,
H 7.19, N 11.93.
1
1
analysis. The purity of the HMF was evaluated by H NMR spectros-
copy following air drying and dissolving in water and extraction
into ethyl acetate (Figure S4). In the recycling study the upper
DME phase was collected every hour and a new portion of solvent
was added for 6 cycles. A new portion of cellulose was added
every 4 h. Each collected sample was analyzed immediately.
Synthesis of IL 4
Stability tests
1-(Trimethylsilyl)imidazole (0.028 mol, 3.985 g) and (2-chloroethyl)-
benzene (0.057 mol, 7.97 g) were stirred at 808C for 48 h. The re-
sulting IL was that was washed with diethyl ether (3ꢃ10 mL) and
dried under vacuum (yield=90%). 1H NMR (400 MHz, CD2Cl2,
258C): d=11.2 (s, 1H), 7.3–7.37 (m, 5H), 4.61 (t, J=7 Hz, 2H),
3.25 ppm (t, J=7 Hz, 2H), 13C NMR (CDCl3, 258C): d=143.9, 136.3,
129.1, 128.9, 127.6, 123.3, 121.5, 50.4, 36.6, 35.8, 9.8 ppm. ESI-MS
(m/z) 277.17 [cation]+. Elemental analysis (%) for C19H21ClN2
(312.14): calcd. C 72.95, H 6.77, N 8.95; found: C 72.98, H 6.64, N
9.09.
HMF (0.16 mmol, 20 mg) and CrCl2 (0.019 mmol, 2.3 mg,) were
placed in
a
glass vial containing [C2OHmim]Cl (500 mg),
[C2OHmim]Cl/IL 1 (500/50 mg) or [C2OHmim]Cl/IL 4 (450/50 mg).
The vial was sealed and the reaction mixture was heated to 1008C
for 1 h. After this time the mixture was cooled to RT and diluted
with water and methanol (4:1, 25 mL) for analysis. The initial
amount of HMF was recovered in all systems. Next, glucose
(0.028 mmol, 5 mg) was added to each vial described above and
tested under identical reaction conditions. With [C2OHmim]Cl, HMF
was recovered in 43% yield and for the mixture of [C2OHmim]Cl/IL
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ChemSusChem 2016, 9, 1 – 9
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