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80ꢀꢁꢁꢁꢂꢀX. Huanhuan et al.: Two new 1-acetyl-3-alkylimidazolium ionic liquids
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UV-Vis spectra were measured on an Analytikjena Specord 210 Plus
instrument. Elemental analysis was performed on a Vario EL analysis
system.
1-acetylimidazole
3
3
a
b
1
-Acetyl-3-ethylimidazolium
iodide (3a)
A mixture of 1-acetylimidazole (11.0 g, 0.1 mol) and iodoethane (32.7
g, 0.3 mol) was heated under reflux for approximately 7 h at 50–60°C.
Upon completion of the reaction, the yellow mixture was cooled to
room temperature and washed with ether several times to remove the
excess iodoethane. Af er crystallization from acetonitrile/ether the
compound was obtained as a light yellow solid: yield 17.2 g (65%);
-
0.1
2
50
300
350
λ (nm)
400
450
-1
mp 97–99°C; IR: 3152, 3098, 2986, 1757, 1530, 1478, 1388, 961, 790 cm ;
Figure 1ꢀUV-Vis spectra (MeCN) of 1-acetylimidazole, 3a and 3b.
1
H NMR: δ 10.00 (s, 1H), 8.26 (d, 1H, J = 1.6 Hz), 7.99 (d, 1H, J = 1.6 Hz),
4
1
.30 (q, 2H, J = 7 Hz), 2.76 (s, 3H), 1.47 (t, 3H, J = 7 Hz); ESI-MS: m/z
+
39.11 (M , 60), 97.06 (85), 126.60 (100); UV-Vis (CH CN): λ 207 nm
3
max
3
3
(
ε 4.3 × 10 ), 247 nm (ε 2.9 × 10 ). Anal. Calcd for C H N OI: C, 31.60;
a π-π* electron transition, is bathochromically shifted
by 5–6 nm in comparison with 242 nm for 1-acetylimi-
dazole. The bathochromic shift is in agreement with the
electron-donating nature of alkyl groups attached to the
7 11 2
H, 4.17; N, 10.53. Found: C, 31.50; H, 4.12; N, 10.69.
1
imidazole ring. The H NMR spectra and ESI-MS spectra
1
-Acetyl-3-hexylimidazolium
of compounds 3a and 3b are also fully consistent with
iodide (3b)
the assigned structures.
A mixture of 1-acetylimidazole (1.33 g, 0.01 mol) and 1-iodohexane
6.49 g, 0.03 mol) was heated to 50–60°C for 7 h. Upon completion of
(
the reaction, the yellow mixture was cooled to room temperature and
washed with ether and acetone to remove 1-iodohexane. This com-
pound was obtained as a light yellow liquid: yield 1.76 g (55%); IR:
Conclusion
Two 1-acetyl-3-alkylimidazolium ionic liquids were pre-
pared in high purity and moderate yields. Compared with
literature methods, this new method allows the reaction
to be carried out under solvent-free conditions.
-
1 1
3
092, 2931, 2858, 1718, 1668, 1544, 1409, 940, 762 cm ; H NMR: δ 10.00
s, 1H), 8.26 (d, 1H, J = 2.3 Hz), 8.01 (d, 1H, J = 2.3 Hz), 2.75 (s, 3H),
.16 (t, 2H, J = 7 Hz), 1.72 (m, 8H), 1.24 (t, 3H, J = 7 Hz); ESI-MS: m/z
(
4
+
1
95.10 (M , 57), 153.00 (88), 126.60 (100); UV-Vis(CH CN): λ 208 nm
3 max
3
3
(
ε 4.8 × 10 ), 248 nm (ε 3.1 × 10 ). Anal. Calcd for C H N OI: C, 41.01;
11 19 2
H, 5.94; N, 8.69. Found: C, 40.71; H, 5.65; N, 10.12.
Acknowledgments: This work was supported by the pro-
ject of Key Technology Researches on Desiccant Evapo-
ration Cooling System with Medium Temperature Solar
Experimental
The melting point was obtained on a Laboratory Devices XT4 A melt- Energy of MOHURD and Beijing Forestry University Young
ing apparatus and is uncorrected. IR spectra were determined in
Scientist Fund (2008XJS16).
1
KBr disks with a Thermo Nicolet AVATAR 330 FT-IR spectrometer. H
NMR spectra were recorded in DMSO-d on a Joel A600 (600 MHz)
6
spectrometer. ESI-MS spectra were obtained by using a Finnigan
LCQ Deca XP Plus ion trap mass spectrometer (San Jose, CA, USA).
Received March 12, 2013; accepted April 19, 2013; previously
published online May 25, 2013
References
[
1] Wasserscheid, P.; Keim, W. Ionic liquids – new “solutions” for
[2] Welton, T. Room-temperature ionic liquids. Solvents
for synthesis and catalysis. Chem. Rev. 1999, 99,
2071–2083.
transition metal catalysis. Angew. Chem. Int. Ed. Engl. 2000, 39,
3
772–3789.
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