Physicochemical Properties of Long Chain Alkylated Imidazolium Based Chloride and Bis(trifluoromethanesulfonyl)imide Ionic Liquids

Article abstract of DOI:10.1021/acs.jced.7b00242

In this research synthesis, purification and characterization of six long-chain imidazolium based ionic liquids (ILs) including C₁₀, C₁₂, and C₁₄ alkyl chain with chloride and NTf₂ anions was investigated. All of these studied ILs were characterized using NMR, CHNSO, and DSC, and some impurities such as water, chloride, and metal contents were reported. The temperature dependence of some physicochemical properties such as density, dynamic and kinematic viscosity, refractive index, surface tension, and thermal stability of the synthesized ILs were also studied in the range 283.15 to 363.15 K, and the results were compared with those from the literature. Moreover, using the measured data, the thermal expansion coefficient and molar polarizability of the ILs were calculated. On the other hand the effects of alkyl chain length and anion were explained. The results revealed that although the refractive indices and viscosities increased as alkyl chain length increased, the density and surface tension results were reciprocally decreased. Besides, the results suggest that the synthesized ILs were the best choice as fuel additives.

Full text of DOI:10.1021/acs.jced.7b00242

Article
pubs.acs.org/jced
Physicochemical Properties of Long Chain Alkylated Imidazolium
Based Chloride and Bis(trifluoromethanesulfonyl)imide Ionic Liquids
†
†
,‡
‡
Nastaran Hazrati, Majid Abdouss, Ali Akbar Miran Beigi,* Ali Asghar Pasban,
and Mahmoud Rezaei†
†
Department of Chemistry, Amirkabir University of Technology, Tehran, Iran
‡
Research Institute of Petroleum Industry, West Boulevard of Azadi Sport Complex, Tehran, Iran
*
S Supporting Information
ABSTRACT: In this research synthesis, purification and character-
ization of six long-chain imidazolium based ionic liquids (ILs)
including C , C , and C alkyl chain with chloride and NTf2
10
12
14
anions was investigated. All of these studied ILs were characterized
using NMR, CHNSO, and DSC, and some impurities such as
water, chloride, and metal contents were reported. The temperature
dependence of some physicochemical properties such as density,
dynamic and kinematic viscosity, refractive index, surface tension,
and thermal stability of the synthesized ILs were also studied in the
range 283.15 to 363.15 K, and the results were compared with those from the literature. Moreover, using the measured data, the
thermal expansion coefficient and molar polarizability of the ILs were calculated. On the other hand the effects of alkyl chain
length and anion were explained. The results revealed that although the refractive indices and viscosities increased as alkyl chain
length increased, the density and surface tension results were reciprocally decreased. Besides, the results suggest that the
synthesized ILs were the best choice as fuel additives.
28
INTRODUCTION
́
for this work. Domanska and co-workers reported 1-octanol/
■
water partition coefficients of 1-alkyl-3-methylimidazolium
chloride where n = 4, 8, 10, and 12. The melting point,
enthalpies of fusion, and phase transitions were stated in their
paper, but density, viscosity, and other properties of 1-alkyl-3-
methylimidazolium chlorides such as n = 10, 12, and 14 are not
reported.
Ionic liquids (ILs) are salts composed of large organic cations
and anions (inorganic or organic) with melting point below
1
3
73.15 K. They are highly promising materials that offer novel
2
−4
solutions to the chemical industry
as well as to its
2
,5
customers.
As a consequence of the special characteristics (negligible
vapor pressure, thermal stability, high ionic conductivity and
mobility, and large electrochemical window),
attractive for many promising applications and a wide variety
fields of research and processes, such as extraction,
absorption,
electrochemistry.
A wide range of arrangements of cations and anions have
One of the benefits of ionic liquids is that their properties can
be tailored to a given application. Long alkyl chain imidazolium
ILs have a high degree of self-organization, which increases with
the increasing chain length. They display the behavior of both
6
−10
they are
1
1
29,30
1
2,13
14
15,16
lyotropic and thermotropic crystals.
Recently, the advan-
corrosion inhibitors, separations,
and
1
7,18
tages of long hydrocarbon tails as amphiphilic head in the
... .
preparation of ordered self-organized structures have received
30−33
further attention.
In petroleum science long alkyl chain
been used to synthesize ionic liquids as more efficient materials
for specific applications.
1
9−21
ionic liquids with surface active properties are used as
Therefore, terms such as
34−36
22
surfactants in enhanced oil recovery.
Besides, 1-decyl-3-
“designer” or “task-specific” solvents are often applied to ILs.
methylimidazolium tetrafluoroborate in oxidative desulfuriza-
The physicochemical properties of ionic liquids depend on
the nature and size of their cation and anion components.
To gain insight into the nature of ionic liquids, a fundamental
understanding must be established for their thermophysical and
electrochemical properties.
Most of the experimental and modeling studies have been
focused on the imidazolium based ILs. Although synthesis of
chloride and bis(trifluoromethanesulfonyl)imide based ionic
liquids has been reported by many researchers, useful data on
the physical and thermodynamic properties are limited. The
lack of some properties reported in the literature for the studied
ionic liquids and the disagreements in reports were the motives
6
,23,24
tion of diesel exhibited high catalytic activity for the removal of
37
dibenzothiophene in diesel. 1-Alkyl-3-methylimidazolium
hydrogen sulfate (C6−C14) ILs are also applied as surfactants
with catalytic activities, as the authors found that “the co-
catalytic properties, both conversion and selectivity, of
alkylimidazolium hydrogen sulfate ionic liquids noticeably
depended on the alkyl chain lengths, and as a of consequence
25,26
27
Received: March 8, 2017
Accepted: September 13, 2017
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.jced.7b00242
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Journal of Chemical & Engineering Data
Article
Table 1. Reactants and Solvents’ Specifications Used for Synthesis of Ionic Liquids
Initial Mole
Purification
Final Mole
Chemical Name
Methylimidazole
Source
Merck
Fraction Purity
Method
Fraction Purity
Analysis Method
a
≥0.990
≥0.980
≥0.95
≥0.950
≥0.980
≥0.999
Distillation
Distillation
Distillation
Distillation
none
≥0.999
≥0.995
≥0.992
≥0.995
GC
GC
GC
GC
1
1
1
-chlorodecane
Merck
-chlorododecane
Merck
-chlorotetradecane
Merck
Lithium bis(trifluoromethanesulfonyl)imide
Merck
alkalimetric after ionic exchange
GC
Diethyl ether
Merck
none
1
1
1
1
1
1
-decyl-3-methylimidazolium chloride
-dodecyl-3-methylimidazolium chloride
-tetradecyl-3-methylimidazolium chloride
Synthesized
Rotary/vacuum
drying
>0.99
>0.99
>0.99
>0.99
>0.99
>0.99
Karl Fischer titration, Potentiometry
1
and H NMR
Synthesized
Synthesized
Synthesized
Synthesized
Synthesized
Rotary/vacuum
drying
Karl Fischer titration, Potentiometry
1
and H NMR
Rotary/vacuum
drying
Karl Fischer titration, Potentiometry
1
and H NMR
-decyl-3-methylimidazolium
bis(trifluoromethanesulfonyl)imide
Rotary/vacuum
drying
Karl Fischer titration, Potentiometry
1
and H NMR
-dodecyl-3-methylimidazolium
bis(trifluoromethanesulfonyl)imide
Rotary/vacuum
drying
Karl Fischer titration, Potentiometry
1
and H NMR
-tetradecyl-3-methylimidazolium
bis(trifluoromethanesulfonyl)imide
Rotary/vacuum
drying
Karl Fischer titration, Potentiometry
1
and H NMR
a
Gas−liquid chromatography.
3
8
their properties”. Recently the application of 1-dodecyl-3-
Viscosity)). Three milliliters of IL was poured into the
measuring cell of the SVM-3000 viscodensimeter by syringe.
The instrument displays density and dynamic and kinematic
viscosity. Each measurement was repeated to establish a repeat
precision.
methylimidazolium chloride in integral membrane proteome
analysis was studied by Zhao et al.
Additionally, understanding of the structure and features of
NTf based ionic liquids is of great interest due to their
39
2
exclusive physicochemical properties. The measurement of
physicochemical properties such as density, viscosity, surface
tension, and refractive index for 1-alkyl-3-methylimidazolium
bis(trifluoromethanesulfonyl)imides with n = 10, 12, and 14 in
The ring method was used to measure the surface tension of
the ILs, with a KRUSS-K9 tensiometer (Germany). The
equipment was calibrated using ultrapure water and acetone.
The measurement cell was thermostated in a temperature
controller with a temperature stability of ±0.02 K, regulated in
a RC6 LAUDA thermostat. Measurements were performed
between temperatures of 283.15 to 363.15 K. The maximum
40−44
different temperature ranges was reported before.
Herein
the synthesis of these six ILs (1-alkyl-3-methylimidazolium
bis(trifluoromethanesulfonyl)imide and 1-alkyl-3-methylimida-
zolium chloride as n = 10, 12, and 14) is reported, and their
properties were accurately measured at atmospheric pressure
and temperature from 283.15 to 363.15 K.
This research work was conducted as a part of a Ph.D.
project in which ionic liquids are synthesized, characterized,
and used as fuel additives such as water in crude oil emulsion
demulsifier, pour point depressant, and scavenger. Herein the
physical and chemical properties of synthesized ionic liquids
were investigated and the dependence of thermal properties on
cation and anion structure was studied.
−1
experimental uncertainty was ±0.1 mN·m .
Refractive indices were determined using a Rudolph
refractometer model J357 (USA). The apparatus was calibrated
at different temperatures from 283.15 to 363.15 K.
An 851 Titrando, Karl Fischer apparatus supplied by
Metrohm (Switzerland) was used to determine the water
content in the synthesized samples.
The melting point was measured using a differential scanning
calorimeter from PerkinElmer DSC 8000 (USA). Samples were
enclosed in a sample pan and heated from room temperature to
4
23.15 K and then cooled to 173.15 K and heated again to
−1
EXPERIMENTAL SECTION
423.15 K with a scan rate of 10 K min .
All the instruments were under manufacturer recommenda-
tions and calibrated periodically by the related certified
reference material.
■
Materials and Methods. All chemicals and solvents used
in this study were purchased from Merck. The chemicals’
detailed specifications are given in Table 1.
Characterization of CHNSO of the samples was performed
using a Vario max elemental analyzer from Elementar
SYNTHESIS OF IONIC LIQUIDS
■
1
13
19
(Germany). H, C, and F NMR spectroscopy was used to
In this work six ionic liquids containing imidazolium cations
were coupled with two anions chloride (Cl) and bis-
characterize the structure of ionic liquids with a Bruker Avance
5
00 spectrometer (Germany).
The density and viscosity of the ionic liquids were measured
(trifluoromethanesulfonyl)imide (NTf ). Ionic liquids with
2
chloride anion are hydrophilic, while NTf -based ionic liquids
2
using an automated Anton Paar (Austria) SVM-3000
Stabinger viscometer) digital double-tube viscodensimeter.
are immiscible with water.
Synthesis of halide salts: 1-alkyl-3-methylimidazolium
(
−4
−3
The precision was better than ±2 × 10 g·cm for the density
and ±1 × 10− mPa·s for the viscosity with standard
uncertainty of ±0.01 K for temperature. The measurements
were performed based on ASTM D7024 (Standard Test
Method for Dynamic Viscosity and Density of Liquids by
Stabinger Viscometer (and the Calculation of Kinematic
chloride ILs were synthesized according to a similar procedure
4
44,45
described in the literature.
In a typical synthesis, a balloon
containing 0.1 mol of methyilmidazole was cooled in a silicone
oil bath. 0.11 mol of 1-chloroalkane (chlorodecane, chlor-
ododecane, chlorotetradecane) was added dropwise by syringe
to methyilmidazole under vigorous stirring. The mixture was
B
DOI: 10.1021/acs.jced.7b00242
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Journal of Chemical & Engineering Data
Article
Scheme 1. Molecular Structure, Abbreviation, Formula, and Molecular Weight of Synthesized Ionic Liquids
heated to 343.15 K and stirred at this temperature for 72 h
under nitrogen atmosphere. Finally the product was washed 3
times with diethyl ether to remove unreacted materials and
dried at 333.15 K under vacuum.
123.68, 136.30. C H ClN (286.88): calculated C 67.0, H
16 31 2
10.9, N 9.8; found C 67.2, H 11.2, N 9.6.
1
1-Tetradecyl-3-methylimidazolium Chloride. H NMR
(D O, 300 MHz): δ 0.697 (t, 3H) J= Hz, 1.124 (d, 22H), 1.739
2
Synthesis of NTf salts: NTf ionic liquids were synthesized
(d, 2H), 3.894 (s, 3H), 4.123 (q, 2H), 7.326 (d, 2H), 8.647 (s,
2
2
13
in a two-step metathesis procedure. At ease with the
1H). C NMR (D2O, 75 MHz): δ 14.095, 22.58, 29.16, 29.47,
29.64, 29.88, 35.87, 49.38, 121.99, 123.72, 136.197.
C H ClN (314.94): calculated C 68.6, H 11.2, N 8.9;
hydrophobicity of NTf ILs, the anion exchange part was
2
carried out in the aquatic phase. The analogous chloride IL was
18
35
2
dissolved in deionized water; in the other beaker LiNTf was
found C 68.8, H 11.1, N 8.9.
2
dissolved in deionized water. The solution of LiNTf was slowly
added to the IL solution. At the time a white emulsion was
formed. After 15 min of stirring it was separated into two
1-Decyl-3-methylimidazolium Bis(trifluoromethane-
2
1
sulfonyl)imide. H NMR (CDCl , 300 MHz): δ 0.842 (t,
3
3H) J= Hz, 1.228 (d, 14H), 1.732 (d, 2H), 3.788 (s, 3H), 4.093
13
phases. A nonaqueous phase containing NTf ionic liquid was
(q, 2H), 7.380 (d, 2H), 8.742 (s, 1H). C NMR (CDCl , 75
2
3
separated and washed with water until the chloride anion was
removed completely. Then it was dried at 333.15 K under
vacuum.
MHz): δ 13.69, 22.57, 29.15, 29.215, 29.343, 29.581, 30.00,
19
36.09, 50.07, 117.62, 121.88, and 135.868, F NMR (D O, 300
2
MHz): δ − 79.218. C H F N O S (503.52): calculated C
16
27
6
3
4 2
The molecular structures of the cations and anions of the ILs
are shown in Scheme 1. The confirmation of the formation of
ionic liquids was carried out by elemental analysis (CHNOS)
and NMR. The NMR spectra of synthesizes ILs are given in
Figures S1−6 in the Supporting Information.
38.2, H 5.4, N 8.3, O 12.7, S 12.7; found C 38.5, H 5.6, N 8.2,
O 12.9, S 12.6.
1-Dodecyl-3-methylimidazolium Bis(trifluoro-
1
methanesulfonyl)imide. H NMR (CDCl , 300 MHz): δ
3
0.873 (t, 3H) J= Hz, 1.250 (d, 18H), 1.826 (d, 2H), 3.929 (s,
-Decyl-3-methylimidazolium Chloride. 1H NMR
3H), 4.149 (q, 2H), 7.321 (d, 2H), 8.707 (s, 1H). C NMR
13
1
(
D O, 300 MHz): δ 0.684 (t, 3H), 1.099 (d, 14H), 1.732 (d,
(CDCl , 75 MHz): δ 13.97, 22.96, 28.85, 29.28, 29.446, 29.561,
2
3
1
9
2
1
2
H), 3.848 (s, 3H), 4.093 (q, 2H), 7.380 (d, 2H), 8.742 (s,
30.06, 36.27, 50.15, 117.64, 121.89, 123.79, and 135.745,
F
H). 13C NMR (D O, 75 MHz): δ 13.69, 22.52, 26.02, 28.97,
NMR (D O, 300 MHz): δ − 79.104. C H F N O S
2
2
18 31
6
3
4 2
9.27, 29.40, 29.52, 29.80, 35.81, 49.43, 122.5, 123.73, 136.20.
(531.577): calculated C 40.7, H 5.9, N 7.9, O 12.0, S 12.1;
found C 40.9, H 6.0, N 7.9, O 12.2, S 12.0.
C H ClN (258.83): calculated C 65.0, H 10.5, N 10.8; found
14
27
2
C 65.1, H 10.6, N 10.7.
-Dodecyl-3-methylimidazolium Chloride. 1H NMR
D O, 300 MHz): δ 0.690 (t, 3H) J= Hz, 1.133 (d, 18H),
1-Tetradecyl-3-methylimidazolium Bis(trifluoro-
1
1
2
methanesulfonyl)imide. H NMR (CDCl , 300 MHz): δ
3
(
0.852 (t, 3H) J= Hz, 1.231 (d, 22H), 1.744 (d, 2H), 3.902 (s,
1
3
1
8
2
.740 (d, 2H), 3.83 (s, 3H), 4.117 (q, 2H), 3.372 (d, 2H),
3H), 4.103 (q, 2H), 7.325 (d, 2H), 8.698 (s, 1H). C NMR
.726 (s, 1H). 13C NMR (D O, 75 MHz): δ 13.66, 22.51,
(CDCl , 75 MHz): δ 13.99, 22.96, 30.03, 30.61, 31.50, 31.87,
2
3
19
9.00, 29.33, 29.45, 29.64, 29.77, 31.80, 35.80, 49.40, 121.99,
36.19, 50.09, 117.63, 121.88, and 135.97, F NMR (D O, 300
2
C
DOI: 10.1021/acs.jced.7b00242
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Journal of Chemical & Engineering Data
Article
Table 2. Density (ρ), Dynamic Viscosity (η), Kinematic Viscosity (ν), Refractive Index (n ), Surface Tension (σ), and Thermal
D
Expansion (α ) of [C mim][Cl], [C mim][NTf ], [C mim][NTf ], and [C mim][NTf ] from 283.15 to 363.15 K at 101
p
10
10
2
12
2
14
2
a
kPa
ρ/(g·cm−3)
10 α /K
4
η/(mPa·s)
ν/(mm2·s−1
)
nD
σ/(mN·m−1
)
T/K
C mim][Cl]
p
[
10
2
2
3
3
3
3
3
3
3
93.15
98.15
03.15
13.15
23.15
33.15
43.15
53.15
63.15
1.5002
1.4988
1.4972
1.4937
1.4897
1.4864
1.4834
1.4806
1.4788
0.9840
0.9797
0.9744
0.9681
0.9624
0.9564
0.9507
0.9438
6.13
6.16
6.21
6.26
6.31
6.36
6.42
6.47
34.0
30.2
28.4
27.8
27.0
26.2
25.5
3716
1613
778.9
411.2
233.7
141.7
3814
1667
809.4
429.9
245.9
150.2
[
C mim][NTf ]
10 2
273.15
289.15
293.15
298.15
303.15
313.15
323.15
333.15
343.15
353.15
363.15
1.2927
1.2873
1.2823
1.2784
1.2742
1.2653
1.2563
1.2475
1.2394
1.2306
1.2223
6.87
6.85
6.82
6.80
6.78
6.73
6.68
6.63
6.57
6.52
6.46
139.9
101.2
79.17
50.86
34.51
24.50
18.08
13.78
10.79
109.8
79.67
62.53
40.46
27.65
19.76
14.69
11.27
8.885
1.4366
1.4351
1.4336
1.4306
1.4278
1.4250
1.4222
1.4194
1.4166
−
29.8
29.2
28.3
27.5
26.9
26.3
25.7
25.2
[
C mim][NTf ]
12 2
2
2
3
3
3
3
3
3
3
93.15
98.15
03.15
13.15
23.15
33.15
43.15
53.15
63.15
1.2531
1.2480
1.2420
1.2322
1.2241
1.2160
1.2081
1.2000
1.1918
8.14
8.01
7.88
7.62
7.35
7.07
6.79
6.50
6.21
1.4385
1.4370
1.4354
1.4324
1.4295
1.4265
1.4237
1.4209
1.4179
130.5
101.1
63.54
42.41
29.67
21.63
16.31
12.65
105.2
81.77
51.90
34.87
24.55
18.02
13.68
10.69
28.1
27.7
26.9
25.9
24.9
24.1
23.3
22.5
[
C mim][NTf ]
14 2
3
3
3
3
3
3
3
03.15
13.15
23.15
33.15
43.15
53.15
63.15
1.1971
1.1876
1.1800
1.1713
1.1631
1.1546
1.1465
7.32
7.31
7.29
7.28
7.26
7.25
7.23
1.4384
1.4352
1.4322
1.4292
1.4262
1.4233
1.4204
26.3
25.3
24.5
23.7
22.9
22.3
83.54
54.36
37.21
26.58
19.68
70.80
46.37
31.97
23.00
17.16
13.20
15.04
21.7
a
−3
−1
Standard uncertainties u are u(T) = 0.1 K, u(P) = 5 kPa, u(ρ) = 0.010 g·cm , u(η) = 0.08 η, u(n ) = 0.002, and u (σ) = 0.4 mN·m .
D
MHz): δ − 79.178. C H F N O S (559.630): calculated C
Therefore, all studies were performed on [C mim][Cl],
10
2
0
35
6
3
4
2
4
2.9, H 6.3, N 7.5, O 11.4, S 11.5; found C 43.1, H 6.5, N 7.4,
[
C mim][NTf ], [C mim][NTf ], and [C mim][NTf ].
10 2 12 2 14 2
O 12.5, S 11.9.
From the results it is observed that ρ, σ, η, and n data fit in
D
eqs 1 and 2 with different values of correlation parameters
which were found by fitting to the experimental data as listed in
Table 3. An exponential model for the temperature dependence
of viscosity was first proposed by Reynolds in 1886.
Fortunately, a good correlation between experimental data
and the suggested equations (eqs 1 and 2) resulted from
RESULTS AND DISCUSSION
■
Physicochemical Properties of Ionic Liquids. In order
for a full presentation of the physicochemical properties of
liquid state synthesized ILs, experimental density (ρ), dynamic
viscosity (η), kinematic viscosity (ν), refractive index (nD),
surface tension (σ), and thermal expansion (α ) data over a
p
2
range of 283.15 to 363.15 K were obtained as summarized in
Table 2. It was noted that [C mim][Cl], [C mim][NTf ],
calculated R as given in Table 3.
1
0
10
2
2
2
and [C mim][NTf ] were room temperature ILs and
y(ρ, σ, or n ) = a + a T (K) + a T (K )
(1)
(2)
1
2
2
D
0
1
2
[
C mim][NTf ] had a melting point about 307 K. On the
14 2
other hand [C mim][Cl] and [C mim][Cl] were solid at
12
14
2 −1
ln η (mPa·s or mm ·s ) = a /T (K) + a
temperatures lower than 369 and 332.15 K, respectively.
0
1
D
DOI: 10.1021/acs.jced.7b00242
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Journal of Chemical & Engineering Data
Article
Table 3. Evaluated Correlation Parameters of the Density, Viscosity, Refractive Index, and Surface Tension of [C mim][Cl],
1
0
[
C mim][NTf ], [C mim][NTf ], and [C mim][NTf ] from eqs 1 and 2
10 2 12 2 14 2
Physical property
C mim][Cl]
a0
a1
a2
R2
[
10
ρ/(g·cm−3)
η/(mPa·s)
ν/(mm ·s−1)
nD
1.1571
7421.5
7350.1
1.7027
334.59
0.0006
−6.00 × 10−8
0.9991
0.9995
0.9974
0.9983
0.9632
−15.555
−15.302
−0.001
−1.7190
2
1.00 × 10−
0.0024
6
σ/(mN·m−1)
[
[
[
C mim][NTf ]
10
2
ρ/(g·cm−3)
1.6008
3852
−0.0009
−8.3106
−8.3056
−0.0004
−0.3570
6.00 × 10−7
0.9998
0.9951
0.9948
0.9999
0.9987
η/(mPa·s)
ν/(mm ·s−1)
nD
2
3779.1
1.5382
97.428
2.00 × 10−
7
σ/(mN m−1)
0.0004
C mim][NTf ]
12
2
ρ/(g·cm−3)
1.7418
3892.6
3816.2
1.5388
65.406
−0.0011
−8.2452
−8.2046
−0.0004
−0.1556
2.00 × 10−6
0.9992
0.9969
0.9968
0.9999
0.9990
η/(mPa·s)
ν/(mm ·s−1)
nD
2
2.00 × 10−
7
σ/(mN m−1)
0.0001
C mim][NTf ]
14
2
ρ/(g·cm−3)
1.4946
3896.4
3815.7
1.5269
88.773
−0.0009
−8.0508
−7.9597
−0.0003
−0.3144
4.00 × 10−7
0.9997
0.9982
0.9981
0.9996
0.9997
η/(mPa·s)
ν/(mm ·s−1)
nD
2
6.00 × 10−
8
σ/(mN·m−1)
0.0004
DIFFERENTIAL SCANNING CALORIMETRY
number of conformations of the cation−anion pairs. That is
■
why they can organize more regularly ordered ionic networks
The melting points T , for [C mim][Cl] and [C mim][NTf ]
m
n
n
2
47
with higher melting points. On the other hand the lower
(
n = 10, 12, and 14), which were determined by differential
melting point of the NTf salt could be ascribed to the anion’s
2
scanning calorimetry are presented in Table 4, and DSC curves
are given in Figure S7. Also the data from the literature are
tabulated. The melting process results in an endothermic peak
in the DSC curve.
48
inability in hydrogen bonding and electron delocalization.
Conversely, even in water free conditions the strong ability of
hydrogen bonding of chloride leads to connecting cations and
anions to form a hydrogen-bonded network in 1,3-dialkylimi-
49
dazolium halides.
Table 4. Phase Transition Temperatures of the Ionic Liquids
a
at 101 kPa
DENSITY AND THERMAL EXPANSION
■
[
C mim]
[Cl]
Tm (K)
302.11
[NTf2]
Tm (K)
276.19
n
The density experimental results are presented in Tables 2 and
3. They are also shown in graphical form in Figure 1a, along
with comparisons with other experimental data sets taken from
the literature (Figure 1b, c).
n
10
12
14
5
0
51
3
11.2
244.15
52
2
77.33
For [C mim][Cl] and [C mim][NTf ] (n = 10, 12, and 14),
10
n
2
densities were measured as a function of temperature over a
range of melting points to 363.15 K in 10 K increments. The
densities of the studied ILs decrease with increasing temper-
ature, but at a rate less than that of organic solvents. In contrast
with other ILs, the density of [C mim][Cl] is lower than that
369.37
295.65
5
3
54
3
69.78
292.4
307.5
5
5
3
69.8
1
0
−3
467.20
of water at room temperature (0.982 g·cm ) and similarly
decreases with increasing temperature.
5
5
6
2
3
16.25
08.77
3
For all 1-alkyl-3-methylimidazolium salts, the density
a
Standard uncertainties u are u(T) = 0.5 K and u(P) = 5 kPa.
decreases as n is increased because addition of CH to the
2
alkyl chain on the cation decreases the density since the CH
2
49
Ionic liquids have melting points below 373 K. The diversity
group is less dense than the imidazolium ring. Also increasing
the volume occupied by aliphatic carbon chains leads to greater
of anions and cations of ILs in size and interaction leads to
different accumulation of ions. The melting point is a function
of the molecular packing. The van der Waals interactions have a
5
7,58
separation in polar and nonpolar regions.
Interionic
separation between the polar domains (cationic heads and
anions) and nonpolar domains (aliphatic chains) results in the
lower packing efficiency, which finally results in lower
46
slight effect on the melting point. In NTf ionic liquids
2
compared with chloride ILs, the ions are poorly coordinated,
59,60
because of the bigger size and low symmetry. [C mim][Cl] ILs
density.
In this study, the halide salt has significantly
n
are more symmetric than NTf based ILs and have a smaller
lower density than the NTf ILs with the same cation (0.9840
2
2
E
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Journal of Chemical & Engineering Data
Article
Figure 1. Comparison of the density data of (a) [C mim][Cl] (blue triangles), [C mim][NTf ] (green triangles), [C mim][NTf ] (magenta
10
10
2
12
2
triangles), and [C mim][NTf ] (red triangles) in this work. (b) [C mim][NTf ] in this work (green triangles), [C mim][NTf ] in Tome et al.
1
4
2
10
67
2
10
2
6
5
66
42
68
(
[
×), Jacquemin et al. (◇), Tariq et al. (○), Nann et al. (▲), Oliveira et al. (■), (c) [C mim][NTf ] in this work (magenta triangles),
12
2
42
41
69
64
C mim][NTf ] in Tariq et al. (○), Tariq et al. (Δ), Domanska et al. (blue triangles),Santos et al. (orange triangles), [C mim][NTf ] in
1
2
2
14
2
42
this work (red triangles), [C mim][NTf ] in Tariq et al. (−).
1
4
2
Figure 2. (a) Plot of ln η as a function of temperature [C mim][Cl] (blue triangles), [C mim][NTf ] (green triangles), [C mim][NTf ]
10
10
2
12
2
(
magenta triangles), and [C mim][NTf ] (red triangles) in this work. (b) Dependence of viscosity on alkyl chain length in NTf ILs at 313.15 K for
14
2
2
40,73
40,74
[
C mim][NTf ],
[C mim][NTf ],
[C mim][NTf ], [C mim][NTf ], and [C mim][NTf ].
6
2
8
2
10
2
12
2
14
2
−
3
and 1.2784 g·cm , respectively). The density increases with
increasing molecular weight of the anion. Here the molecular
weights of the Cl and NTf2 are 35.5 and 280.1 g/mol,
respectively. Similar behavior was observed for different anions
such as BF4− and PF6 with the same cation and alkyl chain in
αp = (−1/ρ)(∂ρ/∂T)
(3)
where α
is the thermal expansion coefficient, ρ is density (g·
p
−3
cm ), and T is temperature (K). The thermal expansion
coefficients for each of the ILs at the measured temperatures
are summarized in Table 2 and shown in Figure S8.
−
61−63
the ILs structure as documented in the literature.
The values of the isobaric thermal expansion coefficient for
It is necessary to say that some impurities, especially water
and chloride ion, significantly affect volumetric and transport
properties such as density and dynamic viscosity. As shown in
Figure 1 for the synthesized [C mim][NTf ] and [C mim]-
[
6
[
C mim][Cl], [C mim][NTf ], and [C mim][NTf ] are
10
10
2
12
−1
2
−
4
−3
.13, 6.80, and 8.14 × 10 g·cm
K
and that for
−4
−3 −1
C mim][NTf ] in 303.15 K is 7.32 × 10 g·cm K .
14 2
1
0
2
12
[
NTf ], deviations with the literature were less than 0.2%
2
64
DYNAMIC AND KINEMATIC VISCOSITY
The influence of temperature on dynamic viscosity for
except for Santos et al., while in the case of [C mim][NTf ]
■
1
4
2
42
the deviations with Tariq et al. was 1.1% through all the
investigated temperature range. Although further purifications
were carried out to achieve a chloride content less than 10 mg·
kg , however, an average deviation of 1% was observed due to
the hygroscopic nature of these materials.
[C mim][Cl] and [C mim][NTf ] is tabulated in Table 2
1
0
n
2
and shown in Figure 2. Also the kinematic viscosity as a
function of temperature is presented in Table 2 and Figure S9.
In all samples the ILs viscosity tends to decrease as temperature
increases. For [C mim][NTf ] ionic liquids, there is an increase
−1
The coefficients of thermal expansion for the studied ILs are
n
2
defined by the following equation.
in viscosity as cation size gets bulkier. Higher viscosities are due
F
DOI: 10.1021/acs.jced.7b00242
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Journal of Chemical & Engineering Data
Article
4
3
40
Figure 3. Temperature dependence of the viscosity of (a) [C mim][NTf ] in this work (green triangles), Ahosseini et al. (○), Tariq et al. (−),
10
2
71
72
40
68
Fitchett et al. (×), McHale et al. (■). (b) [C mim][NTf ] in this work (magenta triangles), Tariq et al. (−) Domanska et al. (blue circles).
1
2
2
4
0
(
c) [C mim][NTf ] in this work (red triangles), Tariq et al. (−).
14
2
Figure 4. Temperature dependence of the refractive index of (a) [C mim][Cl] (blue triangles), [C mim][NTf ] (green triangles),
10
10
2
[
(
C mim][NTf ] (magenta triangles), and [C mim][NTf ] (red triangles) in this work. (b) [C mim][NTf ] (green triangles), [C mim][NTf ]
12 2 14 2 10 2 12 2
magenta triangles), and [C mim][NTf ] (red triangles) in this work, [C mim][NTf ] (○) [C mim][NTf ] (×), and [C mim][NTf ] (•) Tariq
14
2
10
2
12
2
14
2
41
77
78
et al., and [C mim][NTf ] Lago et al. (green circles), Branco et al. (black circles).
10
2
7
0
to increased van der Waals interaction between the alkyl chains.
An almost linear descending (with the slope of 5.4 mPa·s per n)
dependence of η as a function of the alkyl group length is
observed for [C mim][NTf ], n = 6−14 (Figure 2b). The
result in a decrease of the free volume. That is why
[C mim][Cl] was a highly viscous ionic liquid up to 353.15 K
10
as stated in Table 2 and as it is heated the viscosity reduces
more intensely compared with the other three. The viscosity is
greater than that of most organic solvents and even greater than
that of glycerin. Figure 2a shows a relationship between Ln η
and 1/T for all studied ILs. It was found that [C mim][Cl]
exhibited a slope of two times greater than that of the
n
2
symmetry and molar mass of the anions have a strong influence
on the viscosity of imidazolium based ionic liquids. Low
symmetry NTf anion can decrease the van der Waals forces
10
2
between the cations and anions of ILs. The viscosity of the
corresponding cation with NTf anion.
[
C mim] ILs increases with increasing the rigidity and the
10
2
Several measuring methods have been used earlier to
determine the viscosity of [C mim][NTf ]: concentric
43,72
symmetry of the anion. The chloride-based ILs have a smaller
number of conformations of the anion and of the cation−anion
pairs because of the symmetry. Therefore, they can organize
n
2
40
71
cylinders viscometry, capillary tube, moving piston,
40
4
7
and Stabinger methods have been reported in the literature.
The experimental data obtained from our studies by the
Stabinger method for [C mim][NTf ], [C mim][NTf ], and
more regular ordered ionic networks. Unfortunately a
systematic study about most impurities was not performed by
Tariq et al., but the water and chloride content of ILs was
reported as major contamination. The experimental values for
10
2
12
2
[
C mim][NTf ] were also compared with the literature as
14 2
−1
−1
given in Figure 3. The results were adequately in agreement
with previous reported works (Figure 3a, b, and c), so that their
deviations were less than 1.0%. Obviously this was due to their
impurities and differences in choice of measuring methods.
water and chloride were 70 mg·kg and 20−50 mg·kg ,
respectively. These impurities have an inverse effect on viscosity
values. The presence of water caused the viscosity values to
decrease, while chloride has a positive effect, as previously
reported by Seddon and other researchers. This is one of the
reasons that our results are nearly lower than what is obtained
REFRACTIVE INDEX
■
4
1
by Tariq et al.
The refractive index (n ) of a material is a dimensionless
D
Also the bulkier side chains reduce the rotational freedom of
molecules, which leads to high viscosities for long alkyl chain
ILs. These results suggest a complex relationship, as Watanabe
and co-workers stated; differences observed in the transport
properties may be due to different levels of “ionicity”
number that describes how light propagates through that
medium. It can be used as a measure of the electronic
polarizability of a molecule and can provide useful information
when studying the forces between molecules or their behavior
75,76
in solution.
(
association/disassociation) that they explained from diffusion
The refractive index measurement data for the ILs are given
in Table 2 and they also are presented in Figure 4 along with
and ionic conductivity data. A high level of dissociation may
G
DOI: 10.1021/acs.jced.7b00242
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Article
Figure 5. Surface tension as a function of temperature (a) [C mim][Cl] (blue triangles), [C mim][NTf ] (green triangles), [C mim][NTf ]
10
10
2
12
2
(
magenta triangles), and [C mim][NTf ] (red triangles) in this work. (b) [C mim][NTf ] in this work (green triangles), [C mim][NTf ] Tariq
14 2 10 2 10 2
41 44 79
et al. (□), [C mim][NTf ] Carvalho et al. (○), [C mim][NTf ] Kolbeck et al. (●), (c) [C mim][NTf ] in this work (magenta triangles),
10
2
10
2
12
2
4
1
79
[
[
C mim][NTf ] Tariq et al. (+), [C mim][NTf ] Kolbeck et al. (○). (d) [C mim][NTf ] in this work (red triangles), [C mim][NTf ]
12
2
12
2
14
2
14
2
4
1
C mim][NTf ] Tariq et al. (◇).
10
2
2
data from the literature. In all of the studied ILs and the whole
studied temperature range the refractive index is higher than
⎛
⎞
m
n − 1
D
R = ⎜
⎟V
m
2
⎝
n + 2 ⎠
(4)
D
1
.41 which is above the range of most common organic
3
−1
materials. Such materials with a high refractive index are
required for antireflective coating and photonic devices. It can
where V is the molar volume (cm ·mol ). The calculated R
and Vm values of the ILs are presented in Table S1 in the
Supporting Information along with molar free volume (fm).
m
m
be observed that the refractive index (n ) of the ILs can be
D
ordered as [C mim][NTf ] < [C mim][NTf ] < [C mim]-
Molar free volume (f ) is the unoccupied fraction of the
molar volume of an IL, which can be predicted by eq 5.
m
10
2
12
2
14
[
NTf ] < [C mim][Cl]. Refractive index increases with
2 10
increasing alkyl chain length because of the increasing
electronic polarizability of the molecule, which results in
variation of intermolecular interactions.
f = V − R
m
m
(5)
m
Molar free volumes are related to the solubilities of different
types of solutes in the ILs.
41
For a comparison of the refractive index of the ILs, only for
[
C mim][NTf ], [C mim][NTf ] and [C mim][NTf ] data
10 2 12 2 14 2
41
are presented by Tariq et al. who studied in 4 temperatures
293.15, 283.15, 313.15, and 333.15 K) by standard Abbe
refractometry. The data for [C mim][NTf ] are in a good
SURFACE PROPERTIES
■
(
Surface tension of ILs was measured by the ring method as a
function of temperature from 283.15 to 363.15 K. Experiments
were performed in a homemade heating system. The cell
containing 10 mL of sample was placed in a water circulating
heating system. Temperature was stable (better than 1 K)
which was monitored with an alumel−chromel thermocouple.
The surface tension measurement data are presented in
Table 2, and the plots of σ vs temperature are shown in Figure
1
0
2
correlation with Tariq et al. The impurities such as water and
chloride are different in the samples that is why the data for
[
C mim][NTf ] investigated within this work is about 0.7%
12 2
higher than Tariq et al. and for [C mim][NTf ] it is 0.4%
1
4
2
lower. To best of our knowledge, only one single point at
93.15 K was found by Sigma-Aldrich company (USA) for
refractive index of [C mim][Cl] with a purity grade of 0.960.
The related experimental value was reported 1.501 with a
relative deviation of <0.051% in comparison with our studies.
2
5
. In general, with increases in temperature surface tension
1
0
decreases because cohesive forces decrease with an increase of
molecular thermal activity. The measured data present surface
tension values well above those of conventional organic
solvents, but still lower than the surface tension of water
The molar polarizability (R ) was calculated from molar
m
−1
volume (V ) and refractive index (n ) experimental data using
(72.86 mN m ). In NTf ILs, the surface tension decreases
m
D
2
the Lorentz−Lorenz relation eq 4.
with a rise in temperature, almost linearly. [C mim][Cl], with
10
H
DOI: 10.1021/acs.jced.7b00242
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Journal of Chemical & Engineering Data
Article
Table 5. Impurities of the Synthesized Ionic Liquids
Species
[C mim][Cl]
[C mim][Cl]
12
[C mim][Cl]
14
[C mim][NTf ]
[C mim][NTf ]
[C mim][NTf ]
1
0
10
2
12
2
14
2
a
−1
Water content , mg·kg
117
184
123700
<10
119
112700
<10
260
<10
249
<10
230
<10
b
−1
Chloride , mg·kg
137200
<10
b
−1
Bromide , mg·kg
<10
<10
<10
c
−1
Sulfate , mg·kg
<5.0
<5.0
<5.0
<5.0
<0.2
<0.001
<5.0
<0.2
<0.001
<5.0
<0.2
<0.001
c
−1
Heavy metals (as Pb), mg·kg
Ash content , mass %
<0.2
<0.2
<0.2
d
<0.001
<0.001
<0.001
a
b
The water content results are obtained by Karl Fischer titration after the drying treatment described in the Experimental Section. Test method =
c
d
potentiometry. Test method = turbidimetry. Test method = electric furnace and gravimetry.
a high viscosity, has a lower surface tension than that of water.
Different types of arrangements of ions at the surface of liquid,
such as the ratio of the polar to nonpolar moieties of the ionic
liquids changing by chain length increasing, result in reduction
in surface tension. The major source of error in the
measurement of surface tension of ILs is the water content
and other impurities, which is normally reduced to a large
extent prior to experimental session by mild heating under
refractive index data were used to calculate the molar refraction
of the ionic liquids using Lorentz−Lorenz equations.
The experimental data of each were correlated with the
expected equation, and the parameters were calculated.
Reported values from data available in the literature were
compared with the measured data. Deviations between
reported values from different researchers are mostly a
consequence of both the presence of impurities and poor
temperature control. The stated information can be used for
theoretical and experimental studies with considering the
impurities and their quantity.
42
vacuum. Figure 5 also shows the data from Tariq et al.,
7
9
44
Kolbeck et al., Carvalho et al. They used the pendant drop
shape method for measurements.
The fact that the surface tension is a property sensitive to the
presence of small amounts of impurities and measurement
method explains the differences between the literature and our
measurements. In the case of [C mim][NTf ], Carvalho et
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.jced.7b00242.
■
*
S
1
0
2
4
4
−1
al. measurements are 2.4 mN m 4 mean higher than that of
2
79
our study and those of Tariq et al. and Kolbeck et al.
NMR spectra (Figures S1−6) and DSC curve (Figure
S7), thermal expansion coefficient (α ) (Figure S8),
kinematic viscosity (ν) (Figure S9), molar polarizability
It must be noted that impurities can have dramatic effects on
the chemistry and physical properties of the ionic liquids. In the
synthesis of ILs the impurities either need to be eliminated
completely during synthesis or a material with a clearly defined
amount of impurities needs to be investigated. So that the
impurities should be prevented or removed as far as possible
during the preparation of the ionic liquid.
p
(
R ), molar volume (V ), and molar free volume (f )
m m m
(
Table S1) as a function of temperature (PDF)
AUTHOR INFORMATION
Corresponding Author
Tel: +98-21-48255042, Fax: +98-21-44739738, E-mail:
■
*
The level of the main impurities in the ionic liquids is
summarized in Table 5.
amiranbeigi@yahoo.com, miranbeigiaa@ripi.ir.
CONCLUSION
ORCID
■
Ali Akbar Miran Beigi: 0000-0002-2261-6004
Notes
The authors declare no competing financial interest.
In this work synthesis of six imidazolium based ionic liquids
containing [C mim][Cl] and [C mim][NTf ] (n = 10, 12, and
n
n
2
1
4) was reported. As [C mim][Cl] and [C mim][Cl] are
12 14
solid, other ILs were characterized in the range 283.15 to
63.15 K. The effect of temperature on physicochemical
properties, density and thermal expansion, refractive index
dynamic and kinematic viscosity, and surface properties at
atmospheric pressure was investigated. Also the alkyl chain and
anion effect on them was discussed.
ACKNOWLEDGMENTS
3
■
The authors would like to acknowledge the funding sources,
both Department of Chemistry, Amirkabir University of
Technology, and Research Institute of Petroleum Industry
(NIOC-RIPI).
The refractive index and viscosity of the studied ionic liquids
increases with the increase of the alkyl chain length, whereas
the densities show the opposite trend. An increase in the alkyl
chain length of the imidazolium cation produces a decrease in
the surface tension of the ionic liquid.
REFERENCES
■
(1) Welton, T. Room−temperature ionic liquids. Solvents for
synthesis and catalysis. Chem. Rev. 1999, 99, 2071−2084.
(2) Rogers, R. D.; Seddon, K. R.; Volkov, S. Green Industrial
Applications of Ionic Liquids; Springer: Berlin, 2012.
The densities of [C mim][Cl] and [C mim][NTf ] in
98.15 K are 0.9840 and 1.2784 m ·kg , respectively. Because
the higher the molecular weight of the anion, the greater the
1
0
10
2
3
−1
(3) Armand, M.; Endres, F.; MacFarlane, D. R.; Ohno, H.; Scrosati,
B. Ionic−liquid materials for the electrochemical challenges of the
future. Nat. Mater. 2009, 8, 621−629.
2
density.
(
́
4) Tome, L. C.; Mecerreyes, D.; Freire, C. S.; Rebelo, L. P. N.;
Viscosity decreases with decreasing symmetry of the anion
can reduce the van der Waals forces between cations and anions
of ILs, which explains the dramatic difference between the
viscosities of [C mim][Cl] and [C mim][NTf ] (3716 and
Marrucho, I. M. Pyrrolidinium−based polymeric ionic liquid materials:
new perspectives for CO 2 separation membranes. J. Membr. Sci. 2013,
4
28, 260−266.
10
10
2
(5) MacFarlane, D. R.; Tachikawa, N.; Forsyth, M.; Pringle, J. M.;
50.864 mPa·s in 313.15 K, respectively). The density and
Howlett, P. C.; Elliott, G. D.; Davis, J. H.; Watanabe, M.; Simon, P.;
I
DOI: 10.1021/acs.jced.7b00242
J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data
Article
Angell, C. A. Energy applications of ionic liquids. Energy Environ. Sci.
(25) Hayes, R.; Imberti, S.; Warr, G. G.; Atkin, R. The nature of
hydrogen bonding in protic ionic liquids. Angew. Chem., Int. Ed. 2013,
52, 4623−4627.
(26) Martins, M. A.; Neves, C. M.; Kurnia, K. A.; Carvalho, P. J.;
Rocha, M. A.; Santos, L. M.; Pinho, S. P.; Freire, M. G. Densities,
viscosities and derived thermophysical properties of water−saturated
imidazolium−based ionic liquids. Fluid Phase Equilib. 2016, 407, 188−
196.
2
014, 7, 232−250.
6) Chiappe, C.; Pieraccini, D. Ionic liquids: solvent properties and
organic reactivity. J. Phys. Org. Chem. 2005, 18, 275−297.
7) Patil, R. A.; Talebi, M.; Xu, C.; Bhawal, S. S.; Armstrong, D. W.
(
(
Synthesis of Thermally Stable Geminal Dicationic Ionic Liquids and
Related Ionic Compounds: An Examination of Physicochemical
Properties by Structural Modification. Chem. Mater. 2016, 28,
4
(
315−4323.
(27) Mousavisafavi, S. M.; Mirkhani, S. A.; Gharagheizi, F.; Akbari, J.
A predictive quantitative structure−property relationship for glass
transition temperature of 1, 3−dialkyl imidazolium ionic liquids. J.
Therm. Anal. Calorim. 2013, 111, 235−246.
8) Rocha, M. A.; Vilas, M.; Rodrigues, A. S.; Tojo, E.; Santos, L. M.
Physicochemical properties of 2−alkyl−1−ethylpyridinium based ionic
liquids. Fluid Phase Equilib. 2016, 428, 112−120.
(
9) Xue, L.; Gurung, E.; Tamas, G.; Koh, Y. P.; Shadeck, M.; Simon,
(
́
28) Domanska, U.; Bogel-Łukasik, E.; Bogel-Łukasik, R. 1-Octanol/
S. L.; Maroncelli, M.; Quitevis, E. L. Effect of Alkyl Chain Branching
on Physicochemical Properties of Imidazolium−Based Ionic Liquids. J.
Chem. Eng. Data 2016, 61, 1078−1091.
Water Partition Coefficients of 1Alkyl-3-methylimidazolium Chloride.
Chem. - Eur. J. 2003, 9, 3033−3041.
(29) Neve, F.; Francescangeli, O.; Crispini, A. Crystal architecture
(
10) Bobrova, L.; Danilov, F.; Protsenko, V. Effects of temperature
and mesophase structure of long−chain N−alkylpyridinium tetra-
chlorometallates. Inorg. Chim. Acta 2002, 338, 51−58.
and water content on physicochemical properties of ionic liquids
containing CrCl · xH O and choline chloride. J. Mol. Liq. 2016, 223,
3
2
(30) Wang, T.; Kaper, H.; Antonietti, M.; Smarsly, B. Templating
Behavior of a Long−Chain Ionic Liquid in the Hydrothermal
Synthesis of Mesoporous Silica. Langmuir 2007, 23, 1489−1495.
4
(
8−53.
11) Canales, R. I.; Brennecke, J. F. Comparison of Ionic Liquids to
Conventional Organic Solvents for Extraction of Aromatics from
(31) Zhou, Y.; Antonietti, M. Preparation of Highly Ordered
Aliphatics. J. Chem. Eng. Data 2016, 61, 1685−1699.
Monolithic Super-Microporous Lamellar Silica with a Room-Temper-
ature Ionic Liquid as Template via the Nanocasting Technique. Adv.
Mater. 2003, 15, 1452−1455.
(
12) Bahadur, I.; Osman, K.; Coquelet, C.; Naidoo, P.;
Ramjugernath, D. Solubilities of Carbon Dioxide and Oxygen in the
I o n i c L i q u i d s M e t h y l T r i o c t y l A m m o n i u m B i s -
(32) Yu, Z.; Wang, Y.; Liu, X.; Sun, J.; Sha, G.; Yang, J.; Meng, C. A
(
trifluoromethylsulfonyl)imide, 1−Butyl−3−Methyl Imidazolium Bis-
novel pathway for the synthesis of ordered mesoporous silica from
(
trifluoromethylsulfonyl)imide, and 1−Butyl−3−Methyl Imidazolium
diatomite. Mater. Lett. 2014, 119, 150−153.
Methyl Sulfate. J. Phys. Chem. B 2015, 119, 1503−1514.
(33) Kumar, M. A.; Selvam, P. Ionic Liquid Templated Synthesis of
(
13) Moura, L.; Mishra, M.; Bernales, V.; Fuentealba, P.; Padua, A. A.
Hexagonal (IITM−41) and Cubic (IITM−48) Ordered Mesoporous
Silicates. Adv. Porous Mater. 2016, 4, 24−30.
H.; Santini, C. C.; Costa Gomes, M. F. Effect of Unsaturation on the
Absorption of Ethane and Ethylene in Imidazolium−Based Ionic
Liquids. J. Phys. Chem. B 2013, 117, 7416−7425.
(34) Lago, S.; Rodríguez, H.; Khoshkbarchi, M. K.; Soto, A.; Arce, A.
Enhanced oil recovery using the ionic liquid trihexyl (tetradecyl)
phosphonium chloride: phase behaviour and properties. RSC Adv.
(
14) Murulana, L. C.; Singh, A. K.; Shukla, S. K.; Kabanda, M. M.;
Ebenso, E. E. Experimental and Quantum Chemical Studies of Some
Bis(trifluoromethyl−sulfonyl) Imide Imidazolium−Based Ionic
Liquids as Corrosion Inhibitors for Mild Steel in Hydrochloric Acid
Solution. Ind. Eng. Chem. Res. 2012, 51, 13282−13299.
2
(
012, 2, 9392−9397.
35) Hezave, A. Z.; Dorostkar, S.; Ayatollahi, S.; Nabipour, M.;
Hemmateenejad, B. Effect of different families (imidazolium and
pyridinium) of ionic liquids−based surfactants on interfacial tension of
water/crude oil system. Fluid Phase Equilib. 2013, 360, 139−145.
(
15) Berthod, A.; Ruiz-Angel, M.; Carda-Broch, S. Ionic liquids in
separation techniques. J. Chromatogr. A 2008, 1184, 6−18.
16) Pereiro, A.; Araujo, J.; Esperanca, J.; Marrucho, I.; Rebelo, L.
(36) Rodríguez-Palmeiro, I.; Rodríguez-Escontrela, I.; Rodríguez, O.;
(
́
̧
Arce, A.; Soto, A. Characterization and interfacial properties of the
surfactant ionic liquid 1−dodecyl−3−methyl imidazolium acetate for
enhanced oil recovery. RSC Adv. 2015, 5, 37392−37398.
Ionic liquids in separations of azeotropic systems−A review. J. Chem.
Thermodyn. 2012, 46, 2−28.
(
17) Ohno, H. Electrochemical Aspects of Ionic Liquids; Wiley: New
̈
(37) Wang, S.; Li, P.; Hao, L.; Deng, C.; Ren, W.; Lu, H. Oxidative
York, 2011.
18) Lin, Z.; Rozier, P.; Duployer, B.; Taberna, P.−L.; Anasori, B.;
desulfurization of model diesel using a Fenton-like catalyst in ionic
liquid (IL) 1-Decyl-3-methylimidazolium tetrafluoroborate ([Dmim]
BF4). Chem. Eng. Technol. 2017, 40, 555−560.
(
Gogotsi, Y.; Simon, P. Electrochemical and in−situ X−ray diffraction
studies of Ti 3 C 2 T x MXene in ionic liquid electrolyte. Electrochem.
Commun. 2016, 72, 50−53.
(
́
38) Nowicki, J.; Łuczak, J.; Stanczyk, D. Dual functionality of
amphiphilic 1−alkyl−3−methylimidazolium hydrogen sulfate ionic
liquids: surfactants with catalytic function. RSC Adv. 2016, 6, 11591−
(
19) Aparicio, S.; Atilhan, M.; Karadas, F. Thermophysical properties
of pure ionic liquids: review of present situation. Ind. Eng. Chem. Res.
010, 49, 9580−9595.
20) Ma, J.; Ying, Y.; Guo, X.; Huang, H.; Liu, D.; Zhong, C.
1
(
1601.
39) Zhao, Q.; Fang, F.; Liang, Y.; Yuan, H.; Yang, K.; Wu, Q.; Liang,
2
(
Z.; Zhang, L.; Zhang, Y. 1−Dodecyl−3−Methylimidazolium Chlor-
ide−Assisted Sample Preparation Method for Efficient Integral
Membrane Proteome Analysis. Anal. Chem. 2014, 86, 7544−7550.
Fabrication of mixed−matrix membrane containing metal−organic
framework composite with task−specific ionic liquid for efficient CO 2
separation. J. Mater. Chem. A 2016, 4, 7281−7288.
(40) Tariq, M.; Carvalho, P. J.; Coutinho, J. A.; Marrucho, I. M.;
(
21) Rama, R.; Rout, A.; Venkatesan, K.; Antony, M. A novel
Lopes, J. N. C.; Rebelo, L. P. Viscosity of (C 2−C 14) 1−alkyl−3−
methylimidazolium bis (trifluoromethylsulfonyl) amide ionic liquids in
an extended temperature range. Fluid Phase Equilib. 2011, 301, 22−32.
(41) Tariq, M.; Forte, P.; Gomes, M. C.; Lopes, J. C.; Rebelo, L.
Densities and refractive indices of imidazolium−and phosphonium−
based ionic liquids: Effect of temperature, alkyl chain length, and
anion. J. Chem. Thermodyn. 2009, 41, 790−798.
phosphoramide task specific ionic liquid for the selective separation of
plutonium (IV) from other actinides. Sep. Purif. Technol. 2017, 172, 7−
15.
(
22) Earle, M. J.; Seddon, K. R. Ionic liquids. Green solvents for the
future. Pure Appl. Chem. 2000, 72, 1391−1398.
23) Raj, J. J.; Wilfred, C. D.; Shah, S. N.; Pranesh, M.; Mutalib, M.
(
A.; Lethesh, K. C. Physicochemical and thermodynamic properties of
imidazolium ionic liquids with nitrile and ether dual functional groups.
J. Mol. Liq. 2017, 225, 281−289.
(42) Tariq, M.; Serro, A. P.; Mata, J. L.; Saramago, B.; Esperanc a̧ , J.
M.; Lopes, J. N. C.; Rebelo, L. P. N. High-temperature surface tension
and density measurements of 1-alkyl-3-methylimidazolium bistrifla-
mide ionic liquids. Fluid Phase Equilib. 2010, 294, 131−138.
(
24) Rogers, R. D.; Seddon, K. R. Ionic liquids−−solvents of the
future? Science 2003, 302, 792−793.
J
DOI: 10.1021/acs.jced.7b00242
J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data
Article
(
43) Ahosseini, A.; Scurto, A. M. Viscosity of imidazolium−based
(63) Gouveia, A. S.; Tome,
́
L. C.; Marrucho, I. M. Density, viscosity,
ionic liquids at elevated pressures: Cation and anion effects. Int. J.
Thermophys. 2008, 29, 1222−1243.
(
and refractive index of ionic liquid mixtures containing cyano and
amino acid−based anions. J. Chem. Eng. Data 2016, 61, 83−93.
(64) Santos, D.; Santos, M.; Franceschi, E.; Dariva, C.; Barison, A.;
Mattedi, S. Experimental Density of Ionic Liquids and Thermody-
namic Modeling with Group Contribution Equation of State Based on
the Lattice Fluid Theory. J. Chem. Eng. Data 2016, 61, 348−353.
44) Carvalho, P. J.; Freire, M. G.; Marrucho, I. M.; Queimada, A. J.;
Coutinho, J. A. P. Surface Tensions for the 1−Alkyl−3−
methylimidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquids.
J. Chem. Eng. Data 2008, 53, 1346−1350.
(
45) Dupont, J.; Consorti, C. S.; Suarez, P. A.; de Souza, R. F.
́
(65) Tome, L. I. N.; Carvalho, P. J.; Freire, M. G.; Marrucho, I. M.;
Preparation of 1-Butyl-3-Methyl Imidazolium-Based Room Temper-
Fonseca, I. M. A.; Ferreira, A. G. M.; Coutinho, J. A. P.; Gardas, R. L.
Measurements and Correlation of High−Pressure Densities of
Imidazolium−Based Ionic Liquids. J. Chem. Eng. Data 2008, 53,
1914−1921.
ature Ionic Liquids. Org. Synth. 2003, 34, 236−236.
(
46) Bonho
K.; Grat
ature Molten Salts. Inorg. Chem. 1996, 35, 1168−1178.
47) Qi, J.; Hu, Y.; Zhao, Y.; Li, J. The role of the symmetry and the
̂
te, P.; Dias, A.−P.; Papageorgiou, N.; Kalyanasundaram,
zel, M. Hydrophobic, Highly Conductive Ambient−Temper-
̈
(66) Jacquemin, J.; Ge, R.; Nancarrow, P.; Rooney, D. W.; Costa
Gomes, M. F.; Padua, A. A.; Hardacre, C. Prediction of ionic liquid
́
properties. I. Volumetric properties as a function of temperature at 0.1
(
flexibility of the anion on the characteristics of the nanostructures and
the viscosities of ionic liquids. Chin. J. Chem. Eng. 2015, 23, 1565−
MPa. J. Chem. Eng. Data 2008, 53, 716−726.
1571.
̈
(67) Nann, A.; Mundges, J.; Held, C.; Verevkin, S. P.; Sadowski, G.
(
48) Huddleston, J. G.; Visser, A. E.; Reichert, W. M.; Willauer, H.
Molecular Interactions in 1−Butanol + IL Solutions by Measuring and
Modeling Activity Coefficients. J. Phys. Chem. B 2013, 117, 3173−
D.; Broker, G. A.; Rogers, R. D. Characterization and comparison of
hydrophilic and hydrophobic room temperature ionic liquids
incorporating the imidazolium cation. Green Chem. 2001, 3, 156−164.
3
(
185.
́
68) Oliveira, M.; Domínguez-Perez, M.; Freire, M.; Llovell, F.;
Cabeza, O.; Lopes-da-Silva, J.; Vega, L.; Coutinho, J. Surface tension of
binary mixtures of 1−alkyl−3−methylimidazolium bis (trifluorome-
thylsulfonyl) imide ionic liquids: experimental measurements and
Soft−SAFT modeling. J. Phys. Chem. B 2012, 116, 12133−12141.
(
49) Dong, K.; Zhang, S.; Wang, D.; Yao, X. Hydrogen Bonds in
Imidazolium Ionic Liquids. J. Phys. Chem. A 2006, 110, 9775−9782.
(
50) Domanska, U.; Bogel-Lukasik, E. Measurements and correlation
of the (solid+ liquid) equilibria of [1−decyl−3−methylimidazolium
(69) Domanska, U.; Wlazlo, M. Thermodynamics and limiting
chloride+ alcohols (C2−C12)]. Ind. Eng. Chem. Res. 2003, 42, 6986−
activity coefficients measurements for organic solutes and water in the
i o n i c l i q u i d 1 - d o d e c y l - 3 - m e t h y l i m i d z o l i u m b i s -
6992.
(
51) Dzyuba, S. V.; Bartsch, R. A. Influence of structural variations in
-alkyl (aralkyl)-3-methylimidazolium hexafluorophosphates and bis
trifluoromethylsulfonyl) imides on physical properties of the ionic
liquids. ChemPhysChem 2002, 3, 161−166.
52) Paulechka, E.; Blokhin, A. V.; Rodrigues, A. S. M. C.; Rocha, M.
(
trifluoromethylsulfonyl) imide. J. Chem. Thermodyn. 2016, 103, 76−
5.
70) Tokuda, H.; Hayamizu, K.; Ishii, K.; Susan, M. A. B. H.;
1
8
(
(
Watanabe, M. Physicochemical properties and structures of room
temperature ionic liquids. 1. Variation of anionic species. J. Phys. Chem.
B 2004, 108, 16593−16600.
(
A. A.; Santos, L. M. N. B. F. Thermodynamics of long-chain 1-alkyl-3-
methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquids. J.
Chem. Thermodyn. 2016, 97, 331−340.
(
71) Fitchett, B. D.; Knepp, T. N.; Conboy, J. C. 1−Alkyl−3−
methylimidazolium Bis (perfluoroalkylsulfonyl) imide water−immis-
cible ionic liquids the effect of water on electrochemical and physical
properties. J. Electrochem. Soc. 2004, 151, E219−E225.
(
́
53) Domanska, U.; Mazurowska, L. Solubility of 1, 3−
dialkylimidazolium chloride or hexafluorophosphate or methylsulfo-
nate in organic solvents: effect of the anions on solubility. Fluid Phase
Equilib. 2004, 221, 73−82.
(72) McHale, G.; Hardacre, C.; Ge, R.; Doy, N.; Allen, R. W.;
MacInnes, J. M.; Bown, M. R.; Newton, M. I. Density− viscosity
product of small−volume ionic liquid samples using quartz crystal
impedance analysis. Anal. Chem. 2008, 80, 5806−5811.
(
54) Rocha, M. A. A.; Neves, C. M. S. S.; Freire, M. G.; Russina, O.;
Triolo, A.; Coutinho, J. A. P.; Santos, L. M. N. B. F. Alkylimidazolium
Based Ionic Liquids: Impact of Cation Symmetry on Their Nanoscale
Structural Organization. J. Phys. Chem. B 2013, 117, 10889−10897.
(73) Widegren, J. A.; Magee, J. W. Density, viscosity, speed of sound,
and electrolytic conductivity for the ionic liquid 1−hexyl−3−
methylimidazolium bis (trifluoromethylsulfonyl) imide and its
mixtures with water. J. Chem. Eng. Data 2007, 52, 2331−2338.
(
55) Domanska, U.; Bogel-Lukasik, E.; Bogel-Lukasik, R. Solubility of
1
−dodecyl−3−methylimidazolium chloride in alcohols (C2−C12). J.
Phys. Chem. B 2003, 107, 1858−1863.
56) Migowski, P.; Machado, G.; Texeira, S. R.; Alves, M. C.; Morais,
(74) Tokuda, H.; Tsuzuki, S.; Susan, M. A. B. H.; Hayamizu, K.;
(
Watanabe, M. How ionic are room−temperature ionic liquids? An
indicator of the physicochemical properties. J. Phys. Chem. B 2006,
J.; Traverse, A.; Dupont, J. Synthesis and characterization of nickel
nanoparticles dispersed in imidazolium ionic liquids. Phys. Chem.
Chem. Phys. 2007, 9, 4814−4821.
1
(
10, 19593−19600.
́ ́
75) Seoane, R. G.; Corderí, S.; Gomez, E.; Calvar, N.; Gonzalez, E.
(
́
̃
57) Montalban, M. G.; Bolívar, C. L.; Díaz Banos, F. G.; Víllora, G.
J.; Macedo, E. A.; Domínguez, A. n., Temperature dependence and
structural influence on the thermophysical properties of eleven
commercial ionic liquids. Ind. Eng. Chem. Res. 2012, 51, 2492−2504.
Effect of Temperature, Anion, and Alkyl Chain Length on the Density
and Refractive Index of 1−Alkyl−3−methylimidazolium−Based Ionic
Liquids. J. Chem. Eng. Data 2015, 60, 1986−1996.
(
76) Vieira, N.; Reis, P.; Shimizu, K.; Cortes, O.; Marrucho, I.;
(
58) Kolbeck, C.; Lehmann, J.; Lovelock, K.; Cremer, T.; Paape, N.;
Arauj
́
o, J.; Esperanca, J.; Lopes, J. C.; Pereiro, A.; Rebelo, L. A
̧
Wasserscheid, P.; Froba, A.; Maier, F.; Steinruck, H.−P. Density and
thermophysical and structural characterization of ionic liquids with
surface tension of ionic liquids. J. Phys. Chem. B 2010, 114, 17025−
alkyl and perfluoroalkyl side chains. RSC Adv. 2015, 5, 65337−65350.
17036.
(77) Lago, S.; Rodriguez, H.; Soto, A.; Arce, A. Deterpenation of
(
59) Canongia Lopes, J. N.; Padua, A. A. Nanostructural organization
in ionic liquids. J. Phys. Chem. B 2006, 110, 3330−3335.
60) Wang, Y.; Voth, G. A. Unique spatial heterogeneity in ionic
liquids. J. Am. Chem. Soc. 2005, 127, 12192−12193.
61) Huddleston, J. G.; Visser, A. E.; Reichert, W. M.; Willauer, H.
Citrus Essential Oil by Liquid-Liquid Extraction with 1-Alkyl-3-
methylimidazolium Bis(trifluoromethylsulfonyl)amide Ionic Liquids. J.
Chem. Eng. Data 2011, 56, 1273−1281.
(
(78) Branco, A. S. H.; Calado, M. S.; Fareleira, J. M. N. A.; Visak, Z.
(
P.; Lopes, J. N. C. Refraction Index and Molar Refraction in Ionic
D.; Broker, G. A.; Rogers, R. D. Characterization and comparison of
hydrophilic and hydrophobic room temperature ionic liquids
incorporating the imidazolium cation. Green Chem. 2001, 3, 156−164.
Liquid/PEG200 Solutions. J. Solution Chem. 2015, 44, 431−439.
(79) Kolbeck, C.; Lehmann, J.; Lovelock, K. R. J.; Cremer, T.; Paape,
N.; Wasserscheid, P.; Fro
and Surface Tension of Ionic Liquids. J. Phys. Chem. B 2010, 114,
7025−17036.
̈
̈
ba, A. P.; Maier, F.; Steinruck, H. P. Density
(
62) Fredlake, C. P.; Crosthwaite, J. M.; Hert, D. G.; Aki, S. N.;
Brennecke, J. F. Thermophysical properties of imidazolium−based
ionic liquids. J. Chem. Eng. Data 2004, 49, 954−964.
1
K
DOI: 10.1021/acs.jced.7b00242
J. Chem. Eng. Data XXXX, XXX, XXX−XXX