Physical properties of binary and ternary mixtures of ethyl acetate, ethanol, and 1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide at 298.15 K

Article abstract of DOI:10.1021/je800899w

Densities, viscosities, and refractive indices for binary and ternary mixtures of ethanol, ethyl acetate, and l-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide have been determined at 298.15 K and atmospheric pressure. Excess molar volumes, and viscosity and molar refraction changes of mixing have been calculated from the measured physical properties. These changes of mixing have been adequately fitted to the Redlieh - Kister polynomial equation. The adjustable parameters and the standard deviations between experimental and calculated values are reported.

Full text of DOI:10.1021/je800899w

1022
J. Chem. Eng. Data 2009, 54, 1022–1028
Physical Properties of Binary and Ternary Mixtures of Ethyl Acetate, Ethanol,
and 1-Octyl-3-methyl-imidazolium Bis(trifluoromethylsulfonyl)imide at 298.15 K
Alfonsina E. Andreatta,† Alberto Arce,* Eva Rodil, and Ana Soto
Chemical Engineering Department, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain
Densities, viscosities, and refractive indices for binary and ternary mixtures of ethanol, ethyl acetate, and
1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide have been determined at 298.15 K and
atmospheric pressure. Excess molar volumes, and viscosity and molar refraction changes of mixing have
been calculated from the measured physical properties. These changes of mixing have been adequately
fitted to the Redlich-Kister polynomial equation. The adjustable parameters and the standard deviations
between experimental and calculated values are reported.
Introduction
Experimental Section
Materials. Ethyl acetate (ω > 99.8 %) was supplied by
Aldrich, and ethanol (ω > 99.9 %) was supplied by Merck. No
further purification of these products was carried out. The IL,
1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide,
[C8mim][NTf2], was synthesized in our laboratory by reaction
of 1-methylimidazole (Aldrich, > 99 %, GC) with an excess
of 1-chlorooctane (99 %, Aldrich) to produce [C8mim][Cl]. This
chloride was mixed with Li[NTf2] salt in deionized water, and
thus we obtained the [C8min][NTf2] by ion metathesis. More
details of the experimental procedure can be found in earlier
publications.5 After being washed, the purification of [C8min]-
[NTf2] was completed by being heated under high vacuum for
48 h (1 mbar, 353.15 K). The water mass fraction was
determined by means of a Karl Fisher titration method carried
out in a Metrohm 737 KF and resulted in ω ) 36·10-6. The
chloride concentration was 14.2 ·10-6, measured by means of
capillary electrophoresis. The IL was analyzed by 1H NMR and
13C NMR spectroscopy (Supporting Information) to confirm the
absence of any major impurities.
Ionic liquids (ILs) have gained increasing attention during
recent years because of their extraordinary properties.1 More-
over, the large number of cation and anion combinations allows
the modification of their thermodynamic properties. Therefore,
ILs can be adjusted or tuned2 to provide a desired density,
viscosity, melting point, hydrophobicity, miscibility, and so on
to suit the requirements of a particular process. This creates
new opportunities for separation or reaction processes. ILs are
the basis of an emerging technology3 that could significantly
benefit the chemical industry by providing more environmentally
friendly and efficient synthesis and processing systems.
Numerous physical and chemical properties are required for
the synthesis, characterization, and applications of ILs. To design
any process involving ILs on an industrial scale, it is necessary
to know a range of physical properties including viscosity and
density among others. Physical properties are necessary for
hydraulic calculations, fluid transport through pipes and pore
surfaces, mass and energy transfer calculations, and so on.
Table 1 shows a comparison between experimental and
literature6-9 data of density, refractive index, and dynamic
viscosity in addition to the water content of pure components.
Experimental Apparatus and Procedure. All weighing was
carried out in a Mettler Toledo AT 261 balance with an
uncertainty of ( 10-4 g. The uncertainty in the mole fractions
of the prepared mixtures was estimated to be ( 0.0002.
Densities were measured in an Anton Paar DMA 5000 den-
simeter. This instrument automatically corrects the viscosity
influence on density over the whole viscosity range. The
viscosity correction for this densimeter is adequately checked.10
In this work, we investigated the ethanol + ethyl acetate +
1-octyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide
ternary system. The interest of the system is based on the
possibility of using the ILs as entrainers in the extractive
distillation of the mixture ethanol + ethyl acetate.4 The IL has
been selected according to its miscibility with these components,
its low melting point (below room temperature), and its easy
synthesis. Experimental data of densities, F, refractive indices,
nD, and dynamic viscosities, η, of the binary and ternary
mixtures of ethanol, ethyl acetate, and 1-octyl-3-methyl-
imidazolium bis(trifluoromethylsulfonyl)imide were determined
over the entire composition range at 298.15 K and atmospheric
pressure. Moreover, the excess molar volumes, VE, viscosity,
∆η, and molar refraction, ∆R, changes of mixing were
calculated and correlated with composition using the Redlich-
Kister polynomial equations. No comparable data for this ternary
system were found in the surveyed literature.
The uncertainty in the measurement is ( 3·10-5 g·cm-3
.
Refractive indices were measured in an ATAGO RX-5000
refractometer with a Hero Therm thermostat to maintain the
temperature. The uncertainty in the refractive index measure-
ment is ( 4·10-5
.
The kinematic viscosity was determined by micro Ubbelohde
viscometer technique. Three micro Ubbelohde viscometers
(capillaries I, II, and III) were used in the experiments according
to the different viscosity values of the mixtures. The capillaries
are calibrated and credited by the company and verified by
ourselves by measuring the viscosity of different pure liquids.
* Corresponding author. Tel: +34981563100 ext. 16790. Fax: +34981528050.
E-mail: alberto.arce@usc.es.
† Present address: PLAPIQUI, Universidad Nacional del Sur-CONICET,
Camino La Carrindanga Km 7, Casilla 717, 8000 Bah´ıa Blanca, Argentina.
10.1021/je800899w CCC: $40.75
2009 American Chemical Society
Published on Web 02/11/2009

Journal of Chemical & Engineering Data, Vol. 54, No. 3, 2009 1023
Table 1. Physical Properties of the Pure Components at T ) 298.15 K
F/(g·cm-3
literature
)
nD
η/(mPa·s)
component
CASRNa
10-6ω (H2O)
this work
this work
literature
this work
literature
ethyl acetate
ethanol
[C8mim][NTf2]
141-78-6
64-17-5
178631-04-4
167
347
36
0.89440
0.78514
1.32059
0.894556
1.36983
1.35928
1.43298
1.369786
1.359416
1.433317
0.4256
1.054
92.51
0.4266
0.784936
1.08266
1.32076,7 1.32,8 1.321,9
90.0,8 95.0,9
a CASRN: Chemical Abstract Service registry number.
Table 2. Physical and Excess Properties for the Binary Systems at 298.15 K and Atmospheric Pressure
F
η
VE
∆η
x
g·cm-3
nD
mPa·s
cm3 ·mol-1
∆R
mPa·s
x Ethyl Acetate + (1 - x) Ethanol
0.0941
0.1919
0.2836
0.4044
0.5014
0.6085
0.6949
0.7929
0.8957
0.80065
0.81509
0.82727
0.84169
0.85205
0.86253
0.87030
0.87851
0.88660
1.36064
1.36193
1.36309
1.36447
1.36548
1.36649
1.36724
1.36811
1.36895
0.855
0.692
0.619
0.541
0.505
0.467
0.444
0.436
0.424
0.056
0.097
0.127
0.147
0.158
0.154
0.145
0.122
0.076
0.005
0.009
0.013
0.015
0.017
0.016
0.014
0.013
0.007
-0.140
-0.241
-0.257
-0.259
-0.234
-0.204
-0.173
-0.120
-0.067
x Ethyl Acetate + (1 - x) [C8mim][NTf2]
0.0493
0.1112
0.1546
0.2125
0.3102
0.4040
0.4779
0.5967
0.7035
0.8233
0.9016
1.31493
1.30734
1.30155
1.29310
1.27660
1.25753
1.23988
1.20386
1.16022
1.08962
1.02264
1.43216
78.89
65.93
58.25
48.82
34.78
24.15
17.54
9.795
5.384
2.284
1.233
-0.077
-0.005
-0.003
0.005
0.011
0.045
0.030
0.035
0.035
0.044
0.034
0.037
-9.081
-16.35
-20.02
-24.13
-29.17
-31.16
-30.96
-27.77
-22.35
-14.41
-8.254
1.43115
1.43042
1.42930
1.42726
1.42453
1.42219
1.41721
1.41123
1.40097
1.39100
-0.215
-0.312
-0.425
-0.589
-0.730
-0.879
-1.027
-1.120
-1.049
-0.815
x Ethanol + (1 - x) [C8mim][NTf2]
0.0959
0.1162
0.1935
0.2269
0.3304
0.4164
0.5412
0.6012
0.7033
0.8067
0.8967
1.31129
1.30917
1.30029
1.29602
1.28078
1.26519
1.23517
1.21621
1.17346
1.10685
1.01050
1.43164
1.43133
1.43016
1.42965
1.42766
1.42549
1.42143
1.41886
1.41319
1.40447
1.39142
71.28
67.63
55.53
51.54
0.051
0.047
0.036
0.029
0.004
0.001
0.013
0.026
0.039
0.028
0.024
0.022
0.023
0.034
0.025
-12.46
-14.25
-19.28
-20.21
-23.06
-24.54
-23.09
-21.67
-17.93
-12.90
-7.426
39.23
29.89
19.92
15.86
10.25
5.830
3.079
-0.009
-0.070
-0.148
-0.181
-0.264
-0.316
-0.315
Results were found to be in good agreement with published
values. Flow time measurements are performed by the Lauda
processor viscosity system PVS1 with a resolution of 0.01 s.
The temperature of the viscometer was kept constant using a
Lauda clear view thermostat D 20 KP with a through-flow cooler
DLK 10. Viscosity measurements were repeated at least three
times for each sample and were found to be repeatable to within
0.03 s for times less than 100 s and ( 0.5 s for longer times.
The kinematic viscosity of solution υ is given by
tion, ∆R, changes of mixing at 298.15 K and atmospheric
pressure are reported in Tables 2 and 3 for the ethyl acetate +
ethanol + [C8min][NTf2] ternary system and its binary systems:
ethyl acetate + ethanol, ethyl acetate + [C8min][NTf2], and
ethanol + [C8min][NTf2]. The excess molar volumes, VE,
viscosity, and molar refraction changes of mixing were calcu-
lated from experimental values using the following expressions
VE ) V -
x V
(2)
(3)
(4)
∑
M
i
i
i
υ ) K(t - y)
(1)
∆η ) η -
x η
∑
i
i
where υ is the kinematic viscosity, t is the flow time, K is the
capillary constant provided by manufacturer, and y is the kinetic
energy correction used if necessary. Dynamic viscosities are
calculated from kinematic viscosities and densities. The uncer-
tainty for the dynamic viscosity determination is estimated to
be ( 0.5 %.
Temperatures of the densimeter, refractometer, and viscometer
were measured with uncertainties of (( 0.01, ( 0.02, and (
0.005) K, respectively.
i
∆R ) R -
x R
i i
∑
M
i
where VM is the molar volume of the mixture, η is the dynamic
viscosity, RM is the molar refraction of the mixture obtained
from the Lorentz-Lorenz equation, and Vi, ηi, and Ri are the
molar volume, viscosity, and molar refraction, respectively, of
the component i.
Figure 1 shows the excess volumes and viscosity changes of
mixing for the three binary systems: (a) ethyl acetate + ethanol,
(b) ethyl acetate + [C8min][NTf2], and (c) and ethanol+
[C8min][NTf2]. For the ethyl acetate + ethanol binary system,
Results
The densities, F, refractive indices, nD, dynamic viscosities,
η, excess molar volumes, VE, viscosity, ∆η, and molar refrac-

1024 Journal of Chemical & Engineering Data, Vol. 54, No. 3, 2009
Table 3. Physical and Excess Properties for the Ethyl Acetate (1) + Ethanol (2) + [C8mim][NTf2] (3) Ternary System at 298.15 K and
Atmospheric Pressure
F
η
VE
∆η
x1
x2
g·cm-3
nD
mPa·s
cm3 ·mol-1
∆R
mPa·s
0.8849
0.8735
0.7954
0.6802
0.5940
0.5043
0.4189
0.3104
0.2274
0.1905
0.1248
0.0800
0.8748
0.7846
0.6915
0.5910
0.4913
0.3835
0.2797
0.1952
0.1462
0.1078
0.0502
0.8768
0.7742
0.6981
0.5954
0.4921
0.3889
0.2817
0.1993
0.1489
0.0995
0.0424
0.8932
0.7892
0.6998
0.6078
0.5162
0.4132
0.3042
0.2069
0.1578
0.0987
0.0576
0.8999
0.8028
0.7065
0.5911
0.4990
0.3979
0.3119
0.2071
0.1685
0.1118
0.0645
0.8901
0.7900
0.7002
0.5947
0.4877
0.3874
0.2689
0.1848
0.1753
0.1317
0.0370
0.8981
0.8137
0.7173
0.5899
0.4936
0.3880
0.2964
0.1035
0.1138
0.1840
0.2876
0.3650
0.4457
0.5225
0.6200
0.6947
0.7278
0.7869
0.8272
0.0997
0.1715
0.2456
0.3256
0.4050
0.4908
0.5734
0.6406
0.6797
0.7103
0.7561
0.0857
0.1570
0.2099
0.2813
0.3531
0.4249
0.4994
0.5567
0.5917
0.6261
0.6658
0.0638
0.1261
0.1795
0.2345
0.2893
0.3509
0.4160
0.4742
0.5036
0.5389
0.5635
0.0505
0.0995
0.1480
0.2063
0.2528
0.3037
0.3471
0.4000
0.4195
0.4481
0.4719
0.0443
0.0846
0.1208
0.1634
0.2065
0.2469
0.2947
0.3286
0.3324
0.3499
0.3881
0.0294
0.0536
0.0814
0.1181
0.1458
0.1762
0.2026
0.90663
0.90787
0.91647
0.92911
0.93865
0.94876
0.95846
0.97093
0.98048
0.98468
0.99241
0.99776
0.92911
0.95243
0.97543
0.99895
1.02098
1.04363
1.06426
1.08046
1.08956
1.09663
1.10682
0.94728
0.98577
1.01159
1.04336
1.07192
1.09793
1.12262
1.14002
1.15003
1.15956
1.17020
0.95585
1.00541
1.04198
1.07466
1.10346
1.13182
1.15833
1.17936
1.18933
1.20038
1.20775
0.96521
1.02001
1.06452
1.10845
1.13790
1.16575
1.18642
1.20888
1.21641
1.22676
1.23502
0.98547
1.04730
1.09139
1.13322
1.16773
1.19476
1.22172
1.23808
1.23985
1.24764
1.26257
0.99407
1.05407
1.10678
1.15950
1.19054
1.21845
1.23884
1.37241
1.37266
1.37435
1.37686
1.37889
1.38068
1.38257
1.38481
1.38642
1.38705
1.38831
1.38928
1.37615
1.38022
1.38412
1.38800
1.39149
1.39496
1.39804
1.40051
1.40165
1.40272
1.40418
1.37908
1.38552
1.38960
1.39451
1.39884
1.40273
1.40640
1.40852
1.40998
1.41124
1.41273
1.38071
1.38845
1.39430
1.39903
1.40329
1.40722
1.41110
1.41388
1.41526
1.41676
1.41770
1.38193
1.39061
1.39739
1.40394
1.40803
1.41194
1.41486
1.41787
1.41886
1.42028
1.42156
1.38518
1.39468
1.40130
1.40733
1.41238
1.41595
1.41984
1.42183
1.42207
1.42315
1.42512
1.38673
1.39582
1.40358
1.41099
1.41530
1.41909
1.42194
0.498
0.503
0.555
0.679
0.773
0.928
1.076
1.371
1.610
1.824
2.113
2.461
0.588
0.733
0.936
1.199
1.570
2.037
2.726
3.493
4.020
4.540
5.392
0.685
0.930
1.261
1.663
2.392
3.145
4.576
5.829
6.763
7.881
9.352
0.743
1.085
1.610
2.286
3.107
4.382
6.305
8.621
10.05
11.96
13.66
0.800
1.212
1.953
2.980
4.430
6.374
8.577
12.06
13.74
16.28
18.90
0.931
1.547
2.524
3.856
6.229
9.092
13.86
18.21
18.85
21.47
28.31
0.992
1.727
2.906
5.526
8.229
12.79
17.52
-0.081
-0.090
-0.156
-0.223
-0.261
-0.300
-0.327
-0.351
-0.353
-0.345
-0.345
-0.347
-0.250
-0.362
-0.453
-0.511
-0.528
-0.520
-0.483
-0.453
-0.428
-0.415
-0.373
-0.355
-0.528
-0.608
-0.662
-0.644
-0.606
-0.554
-0.485
-0.429
-0.382
-0.337
-0.428
-0.635
-0.737
-0.758
-0.748
-0.676
-0.581
-0.475
-0.439
-0.350
-0.294
-0.482
-0.713
-0.808
-0.813
-0.763
-0.675
-0.566
-0.461
-0.413
-0.328
-0.273
-0.598
-0.829
-0.906
-0.887
-0.801
-0.692
-0.559
-0.429
-0.420
-0.373
-0.162
-0.648
-0.871
-0.944
-0.915
-0.827
-0.693
-0.569
0.013
0.013
0.014
0.020
0.033
0.028
0.034
0.032
0.028
0.023
0.018
0.019
0.015
0.024
0.030
0.035
0.038
0.036
0.034
0.035
0.022
0.022
0.019
0.019
0.033
0.035
0.037
0.044
0.049
0.054
0.027
0.031
0.024
0.021
0.036
0.032
0.047
0.040
0.043
0.035
0.045
0.031
0.026
0.025
0.018
0.023
0.031
0.037
0.048
0.039
0.038
0.043
0.029
0.023
0.023
0.036
0.028
0.029
0.036
0.037
0.055
0.037
0.050
0.023
0.022
0.020
0.021
0.043
0.042
0.046
0.037
0.034
0.025
0.028
-1.062
-1.170
-1.887
-2.898
-3.654
-4.383
-5.076
-5.850
-6.429
-6.578
-6.937
-7.031
-2.252
-3.846
-5.438
-7.113
-8.663
-10.28
-11.59
-12.45
-12.87
-13.09
-13.35
-3.252
-5.931
-7.767
-10.29
-12.51
-14.70
-16.32
-17.41
-17.92
-18.21
-18.36
-3.675
-7.227
-10.04
-12.81
-15.41
-17.99
-20.15
-21.47
-21.88
-22.17
-22.01
-4.223
-8.276
-11.96
-16.23
-19.02
-21.72
-23.47
-24.80
-24.90
-24.96
-24.51
-5.564
-10.47
-14.46
-18.95
-22.49
-25.17
-26.94
-27.23
-27.12
-26.91
-25.30
-6.137
-10.95
-16.11
-21.86
-25.49
-27.88
-29.16

Journal of Chemical & Engineering Data, Vol. 54, No. 3, 2009 1025
Table 3. Continued
F
η
VE
∆η
x1
x2
g·cm-3
nD
mPa·s
cm3 ·mol-1
∆R
mPa·s
0.2087
0.1575
0.1042
0.0538
0.8952
0.7968
0.6913
0.5970
0.4956
0.4014
0.3052
0.2045
0.1600
0.0967
0.0507
0.9031
0.7979
0.7077
0.5961
0.5102
0.4059
0.2967
0.2012
0.1527
0.0984
0.0545
0.2279
0.2426
0.2580
0.2725
0.0203
0.0394
0.0598
0.0781
0.0978
0.1160
0.1347
0.1542
0.1628
0.1751
0.1840
0.0093
0.0194
0.0281
0.0388
0.0471
0.0571
0.0676
0.0768
0.0815
0.0867
0.0909
1.25550
1.26441
1.27292
1.28042
1.00754
1.07980
1.13610
1.17423
1.20682
1.23148
1.25239
1.27074
1.27808
1.28749
1.29387
1.01113
1.09370
1.14388
1.19009
1.21765
1.24463
1.26733
1.28374
1.29110
1.29872
1.30443
1.42415
1.42541
1.42652
1.42758
1.38867
1.39946
1.40764
1.41310
1.41760
1.42096
1.42365
1.42629
1.42715
1.42850
1.42930
1.38906
1.40184
1.40879
1.41523
1.41901
1.42271
1.42574
1.42795
1.42893
1.43013
1.43071
23.50
27.51
32.57
37.90
1.126
2.230
4.029
6.502
10.28
15.35
21.83
30.54
35.37
42.55
47.86
1.138
2.769
4.389
8.007
12.10
18.76
28.46
39.19
45.00
52.99
60.11
-0.403
-0.340
-0.253
-0.170
-0.715
-0.956
-1.024
-0.952
-0.842
-0.721
-0.560
-0.365
-0.308
-0.178
-0.095
-0.745
-1.004
-1.028
-0.951
-0.850
-0.687
-0.493
-0.298
-0.198
-0.087
0.001
0.023
0.025
0.017
0.021
0.037
0.031
0.031
0.042
0.039
0.033
0.012
0.033
0.009
0.021
0.010
0.026
0.060
0.041
0.037
0.033
0.032
0.023
0.022
0.019
0.046
0.014
-28.95
-28.31
-26.75
-24.74
-7.092
-13.31
-19.35
-23.89
-27.65
-29.59
-30.26
-29.03
-27.51
-25.04
-23.15
-7.356
-14.49
-20.38
-26.06
-29.12
-31.15
-30.55
-27.77
-25.99
-22.53
-19.07
Table 4. Polynomial Coefficients and Standard Deviations, σ,
Obtained for Fits of Equation 5 to the VE, ∆η, and ∆R Composition
Data for the Binary Systems
Correlation
The calculated data of VE, ∆η, and ∆R were correlated with
the composition data by the Redlich-Kister polynomial,14 which
for binary mixtures is
property
A0
A1
A2
A3
σ
{x Ethyl Acetate + (1 - x) Ethanol}
VE/(cm3 ·mol-1
∆R
∆η/(mPa·s)
)
0.6489
0.0666
0.0913
0.6009
0.005
0.001
0.013
k
Q ) x x
A x - x
j
(5)
(
)
∑
ij
i
j
k
i
-1.0142
k
{x Ethyl Acetate + (1 - x) [C8mim][NTf2]}
where Qij is VE, ∆η, or ∆R, xi is the mole fraction of component
i, Ak is the polynomial coefficient, and k is the number of the
polynomial coefficient. For ternary systems, the corresponding
equation is
VE/(cm3 ·mol-1
∆R
)
-3.5608 -2.8750
-3.0927 -2.2077 0.011
0.1567
-121.87
0.1388
30.129
0.0130
-6.9516 30.054
0.008
0.331
∆η/(mPa·s)
{x Ethanol + (1 - x) [C8mim][NTf2]}
VE/(cm3 ·mol-1
∆R
)
-0.4330 -1.2497
0.1119 -0.1248
-1.3793 -1.8064 0.009
Q123 ) Q12 + Q23 + Q13 + x1x2x3(A + B(x1 - x2) +
C(x2 - x3) + D(x1 - x3) + E(x1 - x2)2 +
F(x2 - x3)2 + G(x1 - x3)2 + ....) (6)
0.0987
-27.029
0.4952 0.003
0.401
∆η/(mPa·s)
-94.048
30.794
Figure 1a also shows data previously published10-12 by other
authors to establish a comparison. As it can be seen, the excess
molar volumes determined in this work are in good agreement
with those of Pires et al.11 and Gonza´lez et al.12 However, there
is a discrepancy with the data measured by Nikam et al.,13 which
are not in concordance with most published values. In the case
of ∆η, our experimental data are in agreement with the
previously published results.12,13 No comparable data were
found in the surveyed literature for the other binary systems.
where Q123 represents VE, ∆η, or ∆R for the ternary system
and Qij is the Redlich-Kister polynomial for the same property
fitted to the binary systems data.
The Redlich-Kister coefficients for the binary and ternary
systems and the standard deviations obtained in the correlations
are listed in Tables 4 and 5, respectively. The coefficients were
obtained by fitting eqs 5 and 6 by least-squares regression.
Fisher’s F-test was used to define the polynomial degree.
Conclusions
For the ethyl acetate + ethanol + [C8min][NTf2] ternary
system, Figures 2, 3, and 4 show density, refractive index, and
dynamic viscosity isolines, respectively. Figure 5 shows excess
molar volume isolines, and Figure 6 shows the viscosity changes
of mixing isolines.
Density, refractive index, and dynamic viscosity data were
determined for the ethyl acetate + ethanol + [C8mim][NTf2]
ternary system and also for its binary systems at 298.15 K and
atmospheric pressure. The excess molar volumes, VE, viscosity,
Table 5. Polynomial Coefficients and Standard Deviations, σ, Obtained for Fits of Equation 6 to the VE, ∆η, and ∆R Composition Data for the
Ternary System
property
A
B
C
D
E
F
G
σ
VE/(cm3 ·mol-1
∆R
∆η/(mPa·s)
)
-6.7198
-0.0126
27.504
3.3935
0.2847
17.625
-9.2515
1.0119
7.9383
-9.9298
0.3943
2.8134
5.5346
-1.3647
-5.1804
0.2558
-19.491
0.029
0.007
0.29
1.3191

1026 Journal of Chemical & Engineering Data, Vol. 54, No. 3, 2009
Figure 1. Excess molar volume and dynamic viscosity changes of mixing for binary systems at 298.15 K and atmospheric pressure: (a) ethyl acetate (1) +
ethanol (2), (b) ethyl acetate (1) + [C8mim][NTf2] (2), and (c) ethanol (1) + [C8mim][NTf2] (2): ×, this work; 9, ref 11; O, ref 12; 2, ref 13; s, Redlich-Kister
correlation.
Figure 2. Density (g ·cm-3) isolines for {ethyl acetate (1) + ethanol (2) +
Figure 3. Refractive index isolines for {ethyl acetate (1) + ethanol (2) +
[C8mim][NTf2] (3)} at 298.15 K and atmospheric pressure.
[C8mim][NTf2](3)} at 298.15 K and atmospheric pressure.
∆η, and molar refraction, ∆R, changes of mixing were
calculated from the physical properties.
The excess molar volumes for the ethyl acetate +
[C8mim][NTf2] binary system are negative over the whole
composition range and reach a minimum around -1.1
cm3 ·mol-1. Strong ion-dipole interactions between unlike
molecules justify negative values of this property. The ethanol
+ [C8mim][NTf2] binary system show an S-shaped dependence

Journal of Chemical & Engineering Data, Vol. 54, No. 3, 2009 1027
Figure 4. Dynamic viscosity (mPa ·s) isolines for {ethyl acetate (1) +
ethanol (2) + [C8mim][NTf2] (3)} at 298.15 K and atmospheric pressure.
Figure 6. Viscosity change of mixing (mPa ·s) isolines for {ethyl acetate
(1) + ethanol (2) + [C8mim][NTf2] (3)} at 298.15 K and atmospheric
pressure.
more attractive interactions in the mixtures than in the pure
liquids. It reaches a minimum around -1.1 cm3 ·mol-1, which
corresponds to the ethyl acetate + [C8mim][NTf2] binary system.
Viscosity changes of mixing for the ternary systems are negative
with a minimum around -31 mPa·s corresponding to the ethyl
acetate + [C8mim][NTf2] binary system. Values of molar
refraction changes of mixing are so small that it is difficult to
establish any conclusion.
The Redlich-Kister equation was successfully applied to
the correlation of all excess properties of binary and ternary
systems.
Supporting Information Available:
1H NMR and 13C NMR spectra. This material is available free
of charge via the Internet at http://pubs.acs.org.
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Received for review November 24, 2008. Accepted January 19, 2009.
We thank the Universidad de Santiago de Compostela, Ministerio de
Educacio´n y Ciencia (Spain) (project CTQ2006-07687/PPQ), CONICET,
Universidad Nacional del Sur (Argentine), and European Union (project
ALFA II-400-FA) for financial support.
JE800899W