Supplementary Information
Structural Effects of Polyethers and Ionic Liquids in
Their Binary Mixtures on Lower Critical Solution
Temperature Liquid-Liquid Phase Separation
Koichi Kodama, Ryohei Tsuda, Kazuyuki Niitsuma, Takashi Tamura, Takeshi Ueki, Hisashi Kokubo,
and Masayoshi Watanabe*
Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai,
Hodogaya-ku, Yokohama 240-8501, Japan
*mwatanab@ynu.ac.jp
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Preparation and Characterization of Ionic Liquids
The ionic liquids used in this study were synthesized by utilizing the methods described in the
literature.1 [P5222][NTf2] was obtained from Nippon Chemical Industrial Co., Ltd. All the ILs were
dried under vacuum at 60 °C and stored in a glovebox ([O2], [H2O] < 1 ppm).
1,3-Dimethylimidazolium bis(trifluoromethane sulfonyl)imide ([C1mim][NTf2]).
In a three-necked round-bottom flask, methyl iodide (100 g, 0.7 mol) was dissolved in 100 mL of
cyclohexane and stirred at 0 °C in an ice-cooled bath. After the dropwise addition of distilled 1methyl imidazole (47 mL, 0.58 mol), the mixture was stirred overnight at room temperature. The
white precipitate was filtered and dried, followed by repeated recrystallization from 2-propanol/ethyl
acetate to afford 1,3-dimethylimidazolium iodide ([C1mim][I]) as a white solid (yield: 65 g, 50%).
To an aqueous solution of [C1mim][I] (25 g, 0.11 mol), lithium bis(trifluoromethane sulfonyl)imide
(38 g, 0.13 mol) was added and stirred to afford a biphasic solution. The organic phase was separated,
diluted with CH2Cl2, and washed with water until the remaining iodide ions could not be detected by
an AgNO3 solution. After it was dried over anhydrous MgSO4, the solvent was removed, and the
remaining liquid was dried under vacuum at 80 °C to afford 1,3-dimethylimidazolium
bis(trifluoromethane sulfonyl)imide as colorless liquid (yield: 85%). 1H NMR (DMSO-d6, 400 MHz)
: 9.02 (s, 1H), 7.67 (d, 2H, J = 2.7 Hz), 3.84 (s, 6H).
1-Ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([C2mim][NTf2]).
In a three-necked round-bottom flask, ethyl bromide (89.6 mL, 1.2 mol) was dissolved in 100 mL of
cyclohexane and stirred at room temperature. After the dropwise addition of distilled 1-methyl
imidazole (79.5 mL, 1.0 mol), the mixture was stirred overnight at room temperature. The white
precipitate was filtered and dried, followed by repeated recrystallization from 2-propanol/ethyl acetate
to afford 1-ethyl-3-methylimidazolium bromide ([C2mim][Br]) as a white solid (yield: 146 g, 77%).
To an aqueous solution of [C2mim][Br] (124 g, 0.654 mol), lithium bis(trifluoromethane
sulfonyl)imide (208 g, 0.72 mol) was added and stirred to afford a biphasic solution. The organic
phase was separated, diluted with CH2Cl2, and washed with water until the remaining bormide ions
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could not be detected by an AgNO3 solution. After it was dried over anhydrous MgSO4, the solvent
was removed and the remaining liquid was dried under vacuum at 80 °C to afford 1-ethyl-3methylimidazolium bis(trifluoromethane sulfonyl)imide as a colorless liquid (yield: 85%). 1H NMR
(DMSO-d6, 400 MHz) : 9.10 (s, 1H), 7.77 (t, 1H, J = 1.4 Hz), 7.68 (t, 1H, J = 1.4 Hz), 4.19 (q, 2H, J
= 8.1 Hz), 3.84 (s, 3H), 1.42 (t, 3H, J = 5.4 Hz).
1-Propyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([C3mim][NTf2]).
1-Propyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide was prepared by the modified
synthetic procedure followed to prepare [C2mim][NTf2].
1-Bromopropane was used as a
quarternizing reagent. After the reaction, the solvent was removed and water was added to dissolve
the remaining liquid. The aqueous phase was washed with ethyl acetate to afford a colorless aqueous
solution of 1-propyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([C3mim][Br]). The
solution was directly used for the following anion exchange reaction to afford 1-propyl-3methylimidazolium bis(trifluoromethane sulfonyl)imide as a colorless liquid.
1H
NMR (DMSO-d6,
400 MHz) : 9.09 (s, 1H), 7.75 (t, 1H, J = 1.4 Hz), 7.70 (t, 1H, J = 1.4 Hz), 4.12 (t, 2H, J = 6.8 Hz),
3.85 (s, 3H), 1.87–1.74 (m, 2H), 0.86 (t, 3H, J = 8.1 Hz).
1-Butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([C4mim][NTf2]). 1-Butyl-3methylimidazolium bis(trifluoromethane sulfonyl)imide was prepared by a similar synthetic
procedure to that followed to prepare [C2mim][NTf2] to afford a colorless liquid. 1H NMR (DMSOd6, 400 MHz) : 9.10 (s, 1H), 7.76 (t, 1H, J = 2.7 Hz), 7.69 (t, 1H, J = 1.4 Hz), 4.16 (t, 2H, J = 6.8
Hz), 3.85 (s, 3H), 1.82–1.71 (m, 2H), 1.33–1.20 (m, 2H), 0.90 (t, 3H, J = 8.1 Hz).
1-Propyl-2,3-dimethylimidazolium bis(trifluoromethane sulfonyl)imide ([C3dmim][NTf2]).
1-Propyl-2,3-dimethylimidazolium bis(trifluoromethane sulfonyl)imide was prepared by utilizing
the methods presented in the literature.1 1,2-Dimethylimidazole and 1-bromopropane were used as
reagents and a colorless liquid was obtained. 1H NMR (CDCl3, 400 MHz) : 7.19 (dd, 2H, J = 6.8
and 2.0 Hz), 3.98 (t, 2H, J = 7.3 Hz), 3.73 (s, 3H), 2.54 (s, 3H), 1.91–1.72 (m, 2H), 0.92 (t, 3H, J =
7.4 Hz).
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1-Butyl-2,3-dimethylimidazolium bis(trifluoromethane sulfonyl)imide ([C4dmim][NTf2]).
1-Butyl-2,3-dimethylimidazolium bis(trifluoromethane sulfonyl)imide was prepared by a similar
synthetic procedure to that followed to prepare [C3dmim][NTf2]. 1-Bromobutane was used, and a
colorless liquid was obtained. 1H NMR (CDCl3, 400 MHz) : 7.19 (d, 2H, J = 9.5 Hz), 4.04 (t, 2H,
J = 7.6), 3.98 (s, 3H), 2.60 (s, 3H), 1.81–1.70 (m, 2H), 1.42–1.29 (m, 2H), 0.92 (t, 3H, J = 7.3 Hz).
1-Pentyl-2,3-dimethylimidazolium bis(trifluoromethane sulfonyl)imide ([C5dmim][NTf2]).
1-Pentyl-2,3-dimethylimidazolium bis(trifluoromethane sulfonyl)imide was prepared by a similar
synthetic procedure to that followed to prepare [C3dmim][NTf2]. 1-Bromopentane was used, and the
purification of [C5dmim][Br] was carried out as in the case of [C3mim][Br]. [C5dmim][NTf2] was
obtained as a pale yellow liquid.
1H
NMR (DMSO-d6, 400 MHz) : 7.62 (dd, 2H, J = 9.9 and 2.0
Hz), 4.09 (t, 2H, J = 7.3 Hz), 3.74 (s, 3H), 2.57 (s, 3H), 1.76–1.65 (m, 2H), 1.39–1.18 (m, 4H), 0.87 (t,
3H, J = 7.1 Hz).
1-Hexyl-2,3-dimethylimidazolium bis(trifluoromethane sulfonyl)imide ([C6dmim][NTf2]).
1-Pentyl-2,3-dimethylimidazolium bis(trifluoromethane sulfonyl)imide was prepared by a similar
synthetic procedure to that followed to prepare [C5dmim][NTf2]. 1-Bromohexane was used, and a
pale yellow liquid was obtained.
1H
NMR (DMSO-d6, 400 MHz) : 7.62 (dd, 2H, J = 9.9 and 2.0
Hz), 4.10 (t, 2H, J = 7.3 Hz), 3.74 (s, 3H), 2.57 (s, 3H), 1.70 (t, 2H, J = 6.8), 1.31–1.23 (m, 6H), 0.87
(t, 3H, J = 6.6 Hz).
1-Butyl-2,3,4,5-tetramethylimidazolium bis(trifluoromethane sulfonyl)imide ([C4m4im][NTf2]).
1-Bromobutane and 1,2,4,5-tetramethylimidazole (purified by sublimation) were used, and the
reaction was carried out at 80 °C for a day under a N2 atmosphere. A pale yellow liquid was obtained.
1H
NMR (Acetone-d6, 400 MHz) : 4.18 (t, 2H, J = 7.8 Hz), 3.76 (s, 3H), 2.73 (s, 3H), 2.31 (d, 6H, J
= 7.6 Hz), 1.81–1.69 (m, 2H), 1.50–1.36 (m, 2H), 0.96 (t, 3H, J = 7.3 Hz).
1-Butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]).
[C4mim][Br] was dissolved in water, and then, NaPF6 (1.1eq.) was added and the mixture was
stirred for a day at room temperature. A colorless liquid was obtained.
1H
NMR (Acetone-d6, 400
4
MHz) : 8.82 (s, 1H), 7.68 (t, 1H, J = 1.8 Hz), 7.62 (t, 1H, J = 1.8 Hz), 4.31 (t, 2H, J = 7.3 Hz), 4.01
(s, 3H), 1.92–1.86 (m, 2H), 1.45–1.31 (m, 2H), 0.94 (t, 3H, J = 7.4 Hz).
References
1 (a) Ionic Liquids in Synthesis; Wasserscheid, P., Welton, T., Eds.; Wiley-VCH Verlag, GmbH &
Co, KgaA: Weinheim, 2003. (b) Welton, T. Room-temperature ionic liquids. Solvents for synthesis
and catalysis, Chem. Rev., 99, 2071 (1999). (c) Smiglak, M., Metlen, A. & Rogers, R. D. The
second evolution of ionic liquids: From solvents and separations to advanced materials energetic
examples from the ionic liquid cookbook, Acc. Chem. Res. 40, 1182 (2007). (d) Plechkova, N. V. &
Seddon, K. R. Applications of ionic liquids in the chemical industry, Chem. Soc. Rev. 37, 123
(2008).
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