Chemistry of Materials
Article
2.3.2. 2-(2-Methoxyethoxy)ethyl p-toluenesulfonate. The general
procedure was followed starting from 2-(2-methoxyethoxy)ethanol
(90 mmol, 10.8 g), K2CO3 (300 mmol, 41.46 g) and p-toluenesulfonyl
especially polymers, has not been fully explored yet. Even
though, pyrrolidinium is known to possess a better electro-
chemical stability than imidazolium because of its nonaromatic
character, which can be beneficial for electrochemical
applications.14,15
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chloride (75 mmol, 14.25 g). Clear liquid. Yield: 19.32 g (94%). H
NMR (500 MHz, CDCl3): δ 7.78 (d, 2H, J = 8.3 Hz, Ph), 7.32 (d, 2H,
J = 8.0 Hz, Ph), 4.16 (t, 2H, J = 4.8 Hz, CH2OTs), 3.68 (t, 2H, J = 4.8
Hz, OCH2CH2OTs), 3.57−3.56 (m, 2H, OCH2CH2O), 3.47−3.46
(m, 2H, OCH2CH2O), 3.30 (s, 3H, OCH3), 2.43 (s, 3H, PhCH3).
2.3.3. 2-(2-(2-Methoxyethoxy)ethoxy)ethyl p-toluenesulfonate.
The general procedure was followed starting from 2-(2-(2-
methoxyethoxy)ethoxy)ethanol (90 mmol, 14.78 g), K2CO3 (300
mmol, 41.46 g) and p-toluenesulfonyl chloride (75 mmol, 14.25 g).
Clear liquid. Yield: 19.125 g (66%).1H NMR (500 MHz, CDCl3): δ
7.76 (d, 2H, J = 8.3 Hz, Ph), 7.31 (d, 2H, J = 8.0 Hz, Ph), 4.13 (t, 2H,
J = 4.9 Hz, CH2OTs), 3.65 (t, 2H, J = 4.8 Hz, OCH2CH2OTs), 3.61−
3.55 (m, 6H, OCH2CH2O), 3.50−3.48 (m, 2H, OCH2CH2O), 3.33 (s,
3H, OCH3), 2.41 (s, 3H, PhCH3).
2.4. General Procedure for Iodination. The products were
obtained following literature procedures.19 The p-toluenesulfonate
derivatives (1 equiv.) were dissolved in acetone and sodium iodide
(1.2 equiv.) was added. The reaction mixtures were stirred at room
temperature under nitrogen in the dark for 24 h. The reaction mixtures
were filtered and the solvent removed under reduced pressure. The
products were purified by flash chromatography.
2.4.1. (2-Methoxyethoxy)ethyl Iodide. General procedure was
followed starting from (2-methoxy)ethyl p-toluenesulfonate (60 mmol,
13.82 g) and NaI (72 mmol, 10.79 g) in acetone (150 mL). Yellowish
liquid. Yield: 10.60 g (95%). 1H NMR (500 MHz, CDCl3): δ 3.64 (t,
2H, J = 6.6 Hz, OCH2), 3.39 (s, 3H, OCH3), 3.25 (t, 2H, J = 6.7 Hz,
CH2I).
2.4.2. 2-(2-Methoxyethoxy)ethyl Iodide. General procedure was
followed starting from 2-(2-methoxyethoxy)ethyl p-toluenesulfonate
(60 mmol, 16.46 g) and NaI (72 mmol, 10.79 g) in acetone (150 mL).
Yellowish liquid. Yield: 12.84 g (93%). 1H NMR (500 MHz, CDCl3):
δ 3.73 (t, 2H, J = 6.7 Hz, OCH2CH2I), 3.64−3.62 (m, 2H,
OCH2CH2O), 3.54−3.52 (m, 2H, OCH2CH2O), 3.37 (s, 3H, OCH3),
3.24 (t, 2H, J = 6.8 Hz, CH2I).
This article reports on the synthesis and characterization of a
new class of pyrrolidinium-based poly(ionic liquid) electrolytes.
This was achieved by starting from a diallyl methyl amine
hydrochloride monomer, which was prepared in large quantities
using a modified Eschweiler-Clarke reaction. The correspond-
ing polymer was obtained by free radical polymerization, then
neutralized and subsequently modified with PEG side chains of
different lengths by quaternization reactions. In addition,
several pyrrolidinium ILs with PEG groups were synthesized
and used as plasticizers for these new polymer electrolytes. All
materials revealed excellent thermal stabilities and very good
ionic conductivities, making them suitable for being applied in a
wide range of electrochemical devices.
2. EXPERIMENTAL SECTION
2.1. Materials. Diallylamine (99%), formaldehyde solution (37 wt.
% in H2O), formic acid (98%), p-toluenesulfonyl chloride (≥98%), 2-
methoxyethanol (99.8%), 2-(2-methoxyethoxy)ethanol (≥99.0%), 2-
(2-(2-metoxyethoxy)ethoxy)ethanol (≥97.0%), potassium carbonate
(≥99.0%), sodium methoxide solution (25 wt.% in methanol), sodium
iodide (≥99.0%), 1-methylpyrrolidine (≥99.0%), bis-
(trifluoromethane)sulfonimide lithium salt (≥99.0%) and silver nitrate
solution (1.0 N in H2O) were purchased from Aldrich. 2,2′-Azobis(2-
methylpropionamidine) dihydrochloride (98%), hydrochloric acid (37
wt.% in H2O), N,N-dimethylformamide (DMF, 99.0%), toluene
(99.5%), diethyl ether (99.5%), ethanol (≥99.8%) and acetone
(99.5%) were purchased from Scharlab. 1-Butyl-1-methylpyrrolidinium
bis(trifluoromethane)sulfonimide (PYR14TFSI) was provided by
Solvionic. All chemicals were used as received. Bis(trifluoromethane)-
sulfonimide lithium salt was dried under vacuum at 120 °C for 24 h
before use.
2.4.3. 2-(2-(2-Methoxyethoxy)ethoxy)ethyl Iodide. General proce-
dure was followed starting from 2-(2-(2-methoxyethoxy)ethoxy)ethyl
p-toluenesulfonate (60 mmol, 19.10 g) and NaI (72 mmol, 10.79 g) in
2.2. Synthesis of Diallyl Methyl Amine Hydrochloride. The
product was obtained using a modified Eschweiler-Clarke reaction.16,17
Diallylamine (1 equiv., 0.45 mol, 43.7 g) was slowly added to a
solution of formic acid (5.3 equiv., 2.38 mol, 122 g) cooled to 0 °C in
a 500 mL round-bottom flask. To the resulting clear solution a
formaldehyde solution (37% solution; 1.5 equiv., 0.675 mol, 55 g) was
added and the mixture was stirred at room temperature for 1 h
(evolution of carbon dioxide). After this time, the flask was connected
to a reflux condenser and the reaction mixture was heated overnight at
100 °C. After, the solution was cooled and aqueous HCl (4 N, 2
equiv., 0.9 mol, 225 mL) was added. The crude reaction was
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acetone (150 mL). Yellowish liquid. Yield: 14.80 g (90%). H NMR
(500 MHz, CDCl3): δ 3.73 (t, 2H, J = 6.8 Hz, OCH2CH2I), 3.65−3.62
(m, 6H, OCH2CH2O), 3.54−3.52 (m, 2H, OCH2CH2O), 3.36 (s, 3H,
OCH3), 3.24 (t, 2H, J = 7.0 Hz, CH2I).
2.5. Synthesis of 1-Methylpyrrolidinium-Based Ionic
Liquids. The products were obtained by adapting literature
procedures.5,20 To pyrrolidine (1 equiv.) in toluene the alkyl iodides
(1.2 equiv.) were added. The reaction mixtures were vigorously stirred
at room temperature for 48 h. The formed iodide ionic liquids were
insoluble in toluene and could be separated by decantation. The ionic
liquids were washed with diethylether (3x) and residual solvent was
removed under reduced pressure. The slightly yellow ionic liquids
were stirred in water with activated carbon for 24 h to decolorize and
then filtered. To the aqueous ionic liquid solutions (1.0 equiv.)
bis(trifluoromethane)sulfonimide (LiTFSI, 1.2 equiv.) aqueous
solution was slowly added. The reaction mixtures were stirred at
room temperature. A phase separation was observed due to an anion
exchange of the iodide by the hydrophobic TFSI anion. The ionic
liquids were separated by decantation and successively washed with
water several times. The aqueous phases were tested with AgNO3 until
all lithium iodide was removed. The ionic liquids were dried under
vacuum at 120 °C for 24 h before use.
2.5.1. 1-(2-Methoxyethyl)-1-methylpyrrolidinium bis-
(trifluoromethane)sulfonimide (IL2). The general procedure was
followed starting from methylpyrrolidine (28 mmol, 2.38 g) and (2-
methoxyethoxy)ethyl iodide (34 mmol, 6.80 g) in toluene (10 mL) to
obtain the iodide ionic liquid. Yield: 6.15 g (81%). For the anion
exchange, bis(trifluoromethane)sulfonimide lithium salt (24 mmol,
6.89 g) aqueous solution was slowly added to 1-(2-methoxyethyl)-1-
methylpyrrolidinium iodide (5.42 g, 20 mmol) aqueous solution. Clear
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evaporated to dryness under reduced pressure. H NMR (500 MHz,
CDCl3): δ 5.95 (m, 2H, NCH2CHCH2), 5.62 (m, 4H,
NCH2CHCH2), 3.77 (d, 4H, J = 7.0 Hz, NCH2CHCH2), 2.82 (s,
3H, NCH3).
2.3. General Procedure for the Tosylation of Primary
Alcohols. The products were obtained by adapting literature
procedures.18 A mortar was charged with the alcohol (1.2 equiv.),
K2CO3 (4 equiv.), and p-toluenesulfonyl chloride (1.0 equiv.), and
grinded vigorously for 10 min and allowed to set for another 10 min.
The reaction was followed by TLC (hexane) until total consumption
of tosyl chloride was observed. The product was extracted with diethyl
ether and filtered. The organic layer was washed with water and
KHCO3 (sat. solution) and dried over MgSO4. The solvent was
evaporated under reduced pressure.
2.3.1. (2-Methoxy)ethyl p-toluenesulfonate. The general proce-
dure was followed starting from 2-methoxyethanol (90 mmol, 6.84 g),
K2CO3 (300 mmol, 41.46 g) and p-toluenesulfonyl chloride (75 mmol,
14.25 g). Clear liquid. Yield: 16.35 g (95%).1H NMR (500 MHz,
CDCl3): δ 7.8 (d, 2H, J = 8.2 Hz, Ph), 7.35 (d, 2H, J = 8.1 Hz, Ph),
4.16 (t, 2H, J = 4.7 Hz, CH2OTs), 3.58 (t, 2H, J = 4.8 Hz,
OCH2CH2OTs), 3.30 (s, 3H, OCH3), 2.45 (s, 3H, PhCH3).
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dx.doi.org/10.1021/cm203790z | Chem. Mater. 2012, 24, 1583−1590