Synthesis of chiral Geminal dicationic ionic liquid from amino acids

Article abstract of DOI:10.14233/ajchem.2013.14463

Chiral imidazolium ionic liquids (3) from amino acid were synthesized when reacted with 1,2-dibromoethane, 1,3-dibromopropane, 1,4-dibromobutane, 1,6-dibromohexane and 1,9-dibromononane, respectively, to obtain a series of chiral geminal dicationic ionic liquid (5), The structures of the synthesized compouds were determined by IR, ¹H and ¹³C NMR, this method for the synthesis of chiral geminal dicationic ionic liquid is simple and rapid with high yield and the study for their application is under way.

Full text of DOI:10.14233/ajchem.2013.14463

Asian Journal of Chemistry; Vol. 25, No. 12 (2013), 6721-6723
http://dx.doi.org/10.14233/ajchem.2013.14463
Synthesis of Chiral Geminal Dicationic Ionic Liquid from Amino Acids
1
2,*
2
AIWU YIN , SAIJIN HUANG and CHUANBIN WU
1
2
Department of Life Science and Chemistry, Hunan University of Science and Engineering, Yongzhou, P.R. China
Department of Chemistry Engineering, Hunan Institute of Engineering, Xiangtan, P.R. China
*Corresponding author: E-mail: huangsaijin@sina.cn
(
Received: 21 August 2012;
Accepted: 27 May 2013)
AJC-13557
Chiral imidazolium ionic liquids (3) from amino acid were synthesized when reacted with 1,2-dibromoethane, 1,3-dibromopropane, 1,4-
dibromobutane, 1,6-dibromohexane and 1,9-dibromononane, respectively, to obtain a series of chiral geminal dicationic ionic liquid (5),
1 13
The structures of the synthesized compouds were determined by IR, H and C NMR, this method for the synthesis of chiral geminal
dicationic ionic liquid is simple and rapid with high yield and the study for their application is under way.
Key Words: Chiral imidazolium ionic liquids, Chiral geminal dicationic ionic liquid, Synthesize, Characterization.
1
1
12
gas chromatography , optical resolution of racemates , stereo
T
INTRODUCTION
13
selective polymerization . But there is no report on the synthesis
and application of chiral geminal dicationic ionic liquids.
In this work, chiral imidazolium ionic liquids were
designed from the natural amino acid, then reacted with 1,2-
dibromoethane, 1,3-dibromopropane, 1,4-dibromobutane, 1,6-
dibromohexane and1,9-dibromononane, respectively, to
obtain a series of chiral geminal dicationic ionic liquid
(Scheme-I), the structures of the synthesized compouds were
Since the first report of geminal dicationic ionic liquids
1
in 2003 , much effort has been devoted to the geminal
dicationic ionic liquids because their superior physical prop-
2
erties compared to traditional monocationic ionic liquids . The
3
application as solvents in high-temperature reactions , novel
4
,5
6
high-temperature lubricants , ultrastable separation phases
7
,8
and dye sensitized solar cells have been reported.
It is well known that the chiral monocationic ionic liquids
9,10
are attractive due to their potential for asymmetric synthesis
1
13
determined by IR, H NMR, C NMR and the study for their
application research in synthesis and separation is under way.
,
N
N
N
N
Scheme-I: Synthetic route of chiral geminal dicationic ionic liquid

6
722 Yin et al.
Asian J. Chem.
TABLE-2
EXPERIMENTAL
All the chemical reagents used are of analytical pure
1
H NMR SPECTRA OF COMPOUNDS 5
1
H NMR, δ (ppm)
Compound
grade,1,2-dibromoethane, 1,3-dibromopropane, 1,4-dibromo-
butane, 1,6-dibromohexane and 1,9-dibromononane was
distilled again. Chiral imidazolium ionic liquids 3 from amino
5
5
5
5
5
a2
8.76 (s, 2H), 7.40(s, 2H), 7.34(s, 2H), 4.82(q, 2H), 3.72
(t, 4H), 1.60(d, 6H).
a3
8.77(s, 2H), 7.43(s, 2H), 7.34(s, 2H), 4.80, (q, 2H), 3.80
(t, 4H), 1.71 (m, 2H), 1.62(d, 6H).
14
acid were synthesized according to the literature procedures
1
and the products were determined by IR, H NMR.
a4
8.84(s, 2H), 7.46(s, 2H), 7.41(s, 2H), 4.78 (d, 2H), 3.76
(t, 4H), 1.75 (m, 4H),1.61(d, 6H).
Melting points were recorded on a digital microscope are
a6
8.89(s, 2H), 7.48(s, 2H),7.37(s, 2H), 4.87(q, 2H), 3.78
(t, 4H), 1.86(m, 4H), 1.56(d, 6H), 1.30(m, 4H).
-
uncorrected. IR (KBr) spectra (ν cm ) were obtained on
1
1
13
a9
8.85(s, 2H), 7.44(s, 2H), 7.35(s, 2H), 4.88(q, 2H), 3.79
Nicolet AVATAR 370 spectrometer, H and C NMR spectra
were taken on a Avance 400 NMR spectrometer, using TMS
as internal standard. The specific rotations were measured on
an Optical Instrument Ltd. WZZ-ZS polarimeter made in
Shanghai Jinke.
(
t, 4H), 1.88(m, 4H), 1.58(d, 6H), 1.33-1.40(m, 10H).
8.76(s, 2H), 7.40(s, 2H), 7.36(s, 2H), 4.82(q, 2H), 3.72
t, 4H), 2.22(m, 2H), 1.01 (d, 6H), 0.80 (d, 6H).
5
b2
b3
(
5
8.76(s, 2H), 7.42(s, 2H), 7.38(s, 2H), 4.81, (q, 2H), 3.79
(t, 4H), 2.22(m, 2H), 1.73 (m, 2H), 1.02 (d, 6H), 0.84 (d,
6
H).
8.87(s, 2H), 7.48(s, 2H), 7.42(s, 2H), 4.80 (d, 2H), 3.78
t, 4H), 2.22(m, 2H), 1.76 (m, 4H), 1.04 (d, 6H), 0.87 (d,
H).
9.01(s, 2H), 7.68(s, 2H), 7.67(s, 2H), 4.80 (br, 2H), 3.73
Procedure for the synthesis of chiral geminal dicationic
ionic liquid (5): 0.25 molar of 1,2-dibromoethane, 1,3-dibromo-
propane, 1,4-dibromobutane, 1,6-dibromohexane and 1,9-
dibromononane, resprctively, reacted with 0.5 molar 3 under
5b4
(
6
5b6
(
(
m, 4H), 2.21 (m, 2H), 1.87 (m, 4H), 1.32 (m, 4H), 1.06
d, 6H), 0.80 (d, 6H).
2
the protection of N at room temperature then all the products
were purified by extraction by 200 mL ethyl acetate four times
when reaction solution changed into viscous and vacuum
drying 72 h to get product 4, which on refluxing in 20 mL
concentrated hydrochloric acid for 4 h, evaporated solvent
under reduced pressure to obtain crude products and then
recrystallized to afford the products 5.
5
b9
8.89(s, 2H), 7.62(s, 2H), 7.58(s, 2H), 4.80(q, 2H),
.81(t, 4H), 1.86(m, 4H), 2.24(m, 2H), 1.32-1.39(m,
10H), 1.01 (d, 6H), 0.85 (d, 6H).
H NMR spectra were taken in D O (5), using TMS as internal
3
1
2
standard.
TABLE-3
13
C NMR SPECTRA OF COMPOUNDS 5
RESULTS AND DISCUSSION
13
Compound
C NMR, δ (ppm)
Melting points and optical activity of chiral geminal
dicationic ionic liquid: Generally speaking, most ionic liquid
are low melting, called room temperature ionic liquids, but
the synthesized chiral geminal dicationic ionic liquid 5 have
high melting (Table-1) and with the linkage chains increase,
the melting pionts decrease.
5
a2
a3
14.6, 25.4, 58.6, 122.4, 123.6, 138.7, 172.2
5
14.8, 25.2, 34.8, 58.9, 122.3, 123.4, 137.4, 172.2
14.8, 25.6, 38.6, 64.6, 122.8, 123.0, 137.4, 172.2
15.0, 27.3, 30.3, 54.8, 72.4, 122.8, 123.6, 137.3, 172.2
15.1, 26.3, 28.3, 30.4, 32.5, 54.8, 72.2, 122.7, 123.6,
5a4
5a
6
5
a9
137.2, 172.1
5b2
5b3
5b4
5b6
17.3, 25.3, 28.9,53.1, 70.7, 122.4, 123.5, 138.7, 172.2
17.4, 25.2, 28.3, 52.3,71.7, 122.3, 123.4, 137.4, 172.2
17.9, 25.3, 30.4, 52.1, 72.5, 122.5, 123.7, 137.4, 172.1
TABLE-1
MELTING POINTS AND OPTICAL ACTIVITY OF 5
18.2, 25.2, 27.6, 30.5, 55.0, 73.2, 120.3, 123.4, 137.0,
172.2
25
Compound
T (ºC)
[α]D
+7.4(C2.0 %, CH
+7.8(C2.0 %, CH
+8.3(C2.0 %, CH
+9.4(C2.0 %, CH
+10.6(C2.0 %, CH
-18.4 (C2.0 %, CH
-18.9(C2.0 %, CH
-19.4(C2.0 %, CH
-20.3(C2.0 %, CH
-22.8(C2.0 %, CH
5
5
5
5
5
a2
a3
a4
218
211
205
197
164
224
216
208
201
171
3
OH)
OH)
OH)
OH)
5b9
17.8, 25.2, 26.1, 28.3, 30.0, 32.5, 52.5, 70.2,
122.3,123.5, 137.1, 172.3
3
3
a6
3
geminal dicationic ionic liquid in different solvent were
investigated (Table-4). It was found that all the chiral geminal
dicationic ionic liquid synthesized were dissolved in water
and methanol and insoluble in ethyl acetate, acetone, chloro-
form, which is quite similar to the monocationic ionic liquids
a9
OH)
3
5b2
5b3
5b4
5b6
5b9
3
OH)
OH)
OH)
OH)
OH)
3
3
3
–
with Br as anion.
3
a
Melting points were recorded on a digital microscope and are
uncorrected.
Conclusion
A synthetic route toward a novel chiral geminal dicationic
ionic liquid from amino acids has been described. The solubility
and other physical properties have been preliminary studied,
further investigations for their application is under way.
Synthesis of chiral geminal dicationic ionic liquid: The
synthesis for chiral geminal dicationic ionic liquid 5 is easy to
purify and have high yields and the products were determined
1
by IR, H NMR (Table-2), C NMR (Table-3). Compounds 5
13
ACKNOWLEDGEMENTS
-1
in IR showed absroption at 3424 cm (-OH), 1736 (C=O),
1
629, 1579 ((imidazole).
Solubility of chiral geminal dicationic ionic liquid:
This work is supported by the Construct Program of the Key
Discipline in Hunan Province (2012) and Aid Program for
Science and Technology Innovative Research Team in Higher
Educational Institutions of Hunan Province (2012-318) and
Great attention has been paid to the ionic liquid as a new type
of green solvent. The solubility of the synthesized chiral

Vol. 25, No. 12 (2013)
Synthesis of Chiral Geminal Dicationic Ionic Liquid from Amino Acids 6723
TABLE-4
SOLUBILITIES OF THE CHIRAL GEMINAL
DICATIONIC IONIC LIQUID
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