Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=gpch20 Download by: [University of North Texas] Date: 15 November 2016, At: 10:15 Physics and Chemistry of Liquids An International Journal ISSN: 0031-9104 (Print) 1029-0451 (Online) Journal homepage: http://www.tandfonline.com/loi/gpch20 Ion-specific equation coefficient version of the Abraham model for ionic liquid solvents: determination of coefficients for tributylethylphosphonium, 1-butyl-1- methylmorpholinium, 1-allyl-3-methylimidazolium and octyltriethylammonium cations Bihan Jiang, Melissa Y. Horton, William E. Acree Jr. & Michael H. Abraham To cite this article: Bihan Jiang, Melissa Y. Horton, William E. Acree Jr. & Michael H. Abraham (2016): Ion-specific equation coefficient version of the Abraham model for ionic liquid solvents: determination of coefficients for tributylethylphosphonium, 1-butyl-1-methylmorpholinium, 1-allyl-3-methylimidazolium and octyltriethylammonium cations, Physics and Chemistry of Liquids, DOI: 10.1080/00319104.2016.1218009 To link to this article: http://dx.doi.org/10.1080/00319104.2016.1218009 Published online: 08 Aug 2016. Submit your article to this journal Article views: 25 View related articles View Crossmark data Citing articles: 1 View citing articles
29
Embed
Ion specific equation coefficient version of the Abraham model for ionic liquid solvents determination of coefficients for tributylethylphosphonium 1
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Full Terms & Conditions of access and use can be found athttp://www.tandfonline.com/action/journalInformation?journalCode=gpch20
Download by: [University of North Texas] Date: 15 November 2016, At: 10:15
Physics and Chemistry of LiquidsAn International Journal
Ion-specific equation coefficient versionof the Abraham model for ionic liquidsolvents: determination of coefficientsfor tributylethylphosphonium, 1-butyl-1-methylmorpholinium, 1-allyl-3-methylimidazoliumand octyltriethylammonium cations
Bihan Jiang, Melissa Y. Horton, William E. Acree Jr. & Michael H. Abraham
To cite this article: Bihan Jiang, Melissa Y. Horton, William E. Acree Jr. & Michael H. Abraham(2016): Ion-specific equation coefficient version of the Abraham model for ionic liquid solvents:determination of coefficients for tributylethylphosphonium, 1-butyl-1-methylmorpholinium,1-allyl-3-methylimidazolium and octyltriethylammonium cations, Physics and Chemistry ofLiquids, DOI: 10.1080/00319104.2016.1218009
To link to this article: http://dx.doi.org/10.1080/00319104.2016.1218009
Published online: 08 Aug 2016. Submit your article to this journal
Article views: 25 View related articles
View Crossmark data Citing articles: 1 View citing articles
Ion-specific equation coefficient version of the Abraham modelfor ionic liquid solvents: determination of coefficients fortributylethylphosphonium, 1-butyl-1-methylmorpholinium,1-allyl-3-methylimidazolium and octyltriethylammonium cationsBihan Jianga, Melissa Y. Hortona, William E. Acree Jr.a and Michael H. Abrahamb
aDepartment of Chemistry, University of North Texas, Denton, TX, USA; bDepartment of Chemistry, UniversityCollege London, London, UK
ABSTRACTGas-to-ionic liquid partition coefficient data have been assembled fromthe published chemical literature for solutes dissolved in 1-allyl-3-methy-limidazolium dicyanamide, 1-allyl-3-methylimidazolium bis(trifluoro-methylsulphonyl)imide, octyltriethylammonium bis(trifluomethyl-sulphonyl)imide, tributylethylphosphonium diethylphosphate and 1-butyl-1-methylmorpholinium tricyanomethanide. The published experi-mental data were converted to water-to-ionic liquid partition coefficientsusing standard thermodynamic relationships. Both sets of partition coeffi-cients were correlated with the Abraham solvation parameter model. Thederived Abraham model correlations described the observed partitioncoefficient data to within 0.13 log units. Cation-specific equation coeffi-cients were calculated for each of the cations present in the five ionicliquid solvents studied. The calculated cation-specific equation coefficientscan be combined with previously reported ion-specific equation coeffi-cients for 19 different anions to yield Abraham model correlations forpredicting the partitioning the behaviour of solutes in 76 different anhy-drous ionic liquid solvents.
ARTICLE HISTORYReceived 30 June 2016Accepted 25 July 2016
Ionic liquid (IL) solvents have been successfully employed in separation processes involving theremoval of nitrogen and sulphur heteroatom compounds from crude petroleum products,[1–6]efficient removal of carbon dioxide from other light inorganic gas (nitrogen and oxygen) andcombustion organic gas (methane, ethane, ethene, acetylene) samples,[7–11] and removal of acidicgases (sulphur dioxide and carbon dioxide) from post-combustion flue gas effluents.[12–18]Considerable effort has been expended in experimentally determining the capacity that IL solventshave towards absorbing various organic compounds and separation factors that IL solvents exhibitfor performing various practical chemical separations. Selectivity factors have been measured andcompiled for alkane vs. alkene (hexane/1-hexene,[19,20] cyclohexane/cyclohexene [20]), alkane vs.benzene (hexane/benzene [20,21]) and alkane vs. heteroatom aromatic hydrocarbon (cyclohexane/pyridine,[22] cyclohexane/thiophene,[22] hexane/pyridine,[21] hexane/thiophene [21]) separationsbased on experimentally determined infinite dilution activity coefficients, γ1solute, for the respectivesolutes dissolved in the IL solvents. While the observed thermodynamic data provide valuableinformation regarding whether the desired chemical separation can be achieved using the IL
solvents studied, it is not practical to perform measurements for every organic solute pair dissolvedin every IL solvent. It is estimated that the number of possible IL solvents may exceed 1014 [23]when one considers all of the different cation–anion pair combinations.
To facilitate the use of ILs in industrial processes involving separations, researchers haveturned to predictive methods to generate activity coefficients of solutes dissolved in IL solvents,as well as to estimate other physical properties of IL solvents that may be needed in process designcomputations. Predictive methods have involved both theoretical and semi-theoretical treatments,as well as approaches based on group contribution and molecular fragment schemes, linear freeenergy relationships (LFERs) and quantitative structure–property relationships (QSPRs). Groupcontribution methods have been proposed, which enable one to predict infinite dilution activitycoefficients and gas–to-liquid partition coefficients of solutes dissolved in ILs,[24–26] to predictenthalpies of solvation of organic solutes dissolved in ILs,[27] and to estimate viscosities,[28,29]thermal conductivities,[30,31] isobaric heat capacities,[32–34] surface tensions [35] and densities[36] of ILs at both 298 K and as a function of temperature. In several of the above methods theentire cation was defined as one functional group and the entire counter-anion was defined as asecond functional group.
Our contribution towards facilitating the use of IL solvents in chemical separation processeshas been to develop mathematical correlations based on the Abraham model that enable one topredict infinite dilution activity coefficients and chemical separation factors. The Abraham model[37] is an LFER approach that can describe solute transfer between two condensed phases:
In the present study one of the condensed phases is the IL solvent. Equation (1) will thus describethe water-to-IL solvent partition coefficient, log P, while Equation (2) will describe the gas-to-ILpartition coefficient, log K. Uppercase alphabetic letters on the right-hand side of Equations (1)and (2) represent the properties of the dissolved solute and are called solute descriptors, which areunique to a given solute molecule. Solute descriptors are defined as follows: the solute excessmolar refractivity in units of (cm3 mol–1)/10 (E), the solute dipolarity/polarisability (S), the overallor summation hydrogen-bond acidity and basicity (A and B, respectively), the McGowan volumein units of (cm3 mol–1)/100 (V), and the logarithm of the gas-to-hexadecane partition coefficientat 298 K (L). Once calculated, the solute descriptors can be used to predict log K and log P valuesfor the solute in any IL solvent for which the lowercase equation coefficients (cp,il, ep,il, sp,il, ap,il,bp,il, vp,il, ck,il, ek,il, sk,il, ak,il, bk,il and lk,il) are known. The equation coefficients are unique to the ILsolvent, and provide information regarding the IL properties, such as polarity, polarisability andhydrogen-bonding character. To date IL-specific equation coefficients have been calculated formore than 70 ILs. See Table 1 for a list of the published equation coefficients for the various ILsolvents that have been studied thus far. Included in the tabulation is the statistical informationassociated with each Abraham model correlation expression, which includes: the standard devia-tion (SD) and the number of experimental data points used in the regression analysis (N) tocalculate the equation coefficients. The ionic liquids are listed according to the cation and anionabbreviation (see Table 2 for the names that correspond to the different abbreviations).
The predictive ability of the IL-specific version of the Abraham model (Equations (1) and (2))is limited in applicability to only those IL solvents for which equation coefficients have beendetermined. The model’s predictive ability can be increased by recognising that each term in thelog P and log K correlations corresponds to a different type of solute–IL interaction. Sprunger andco-workers [38–40] split each type of molecular interaction into a cation contribution and anioncontribution:
2 B. JIANG ET AL.
Table1.
IL-specific
equatio
ncoefficientsforgeneratin
gAb
raham
mod
ellogPandlogKequatio
nsfordescrib
ingsolute
transfer
into
anhydrou
sionicliquidsolvents.
Ionicliquid
SolvNo.
ce
sa
bv/l
NSD
Water-to-ionicliquidsolvent
([MBIm]+[Tf 2N]–)
1−0.018
0.416
0.153
−1.312
−4.187
3.347
101
0.131
([MHIm]+[Tf 2N]–)
2−0.065
0.010
0.260
−1.476
−4.313
3.587
750.115
([M3BAm
]+[Tf 2N]–)
30.047
−0.051
0.356
−1.262
−4.400
3.209
570.120
([MOIm]+[BF 4]–)
4−0.115
0.210
0.000
−0.511
−4.338
3.617
590.159
([MBIm]+[PF 6]–)
5−0.056
0.193
0.737
−1.351
−4.526
3.109
860.154
([4-M
BPy]+[BF 4]–)
6−0.032
0.489
0.466
−0.873
−4.143
2.944
380.141
([MBIm]+[BF 4]–)
7−0.082
0.454
0.541
−0.427
−4.583
2.961
660.132
([MEIm]+[EtSO4]–)
8−0.059
−0.013
0.609
1.526
−5.054
2.894
480.138
([MEIm]+[Tf 2N]–)
90.029
0.351
0.202
−1.684
−3.585
3.059
640.119
([M2EIm]+[Tf 2N]–)
100.095
0.299
0.360
−1.906
−3.805
3.177
380.131
([4-M
BPy]+[Tf 2N]–)
11−0.192
−0.219
1.326
−1.021
−4.429
3.545
370.120
([MBIm]+[OtSO4]–)
12−0.050
0.198
0.179
1.146
−5.154
4.008
550.179
([PM2Im]+[BF 4]–)
13−0.603
0.799
0.824
0.883
−4.417
2.636
340.130
([MBIm]+[Trif]–)
14−0.220
0.209
0.479
0.066
−4.314
3.294
520.124
([D2M
Im]+[Tf 2N]–)
15−0.093
−0.052
0.040
−1.620
−4.667
4.034
400.118
([MOIm]+[PF 6]–)
160.085
−0.123
0.000
−1.255
−4.088
3.509
470.156
([EtOHMIm]+[Tf 2N]–)
17−0.402
0.304
0.470
−1.082
−3.512
2.977
790.133
([EtOHMIm]+[PF 6]–)
18−0.541
−0.145
1.102
−0.596
−3.684
2.723
360.169
([HexM3Am]+[Tf 2N]–)
19−0.322
0.242
0.287
−1.383
−4.265
3.513
900.138
([EMIm]+[N(CN) 2]–)
20−0.329
0.326
0.909
0.933
−4.540
2.904
720.127
([(Hexom
) 2Im]+[Tf 2N]–)
210.107
−0.628
0.747
−1.441
−4.808
3.750
340.106
([Hexom
MIm]+[Tf 2N]–)
22−0.039
−0.645
1.184
−1.374
−4.779
3.609
340.108
([CNPrMIm]+[N(CN) 2]–)
23−0.928
0.373
1.224
1.042
−4.307
3.046
440.150
([MeoeM
Im]+[Tf 2N]–)
24−0.150
0.012
0.818
−1.289
−4.263
3.116
490.129
([(Meo) 2Im]+[Tf 2N]–)
25−0.412
−0.104
0.761
−1.124
−3.776
3.055
460.103
([MEIm]+[E2PO4]–)
260.022
0.289
0.434
3.796
−5.041
3.346
380.165
([H3TdP
]+[Tf 2N]–)
27−0.155
0.163
−0.029
1.271
−5.042
4.246
590.136
([Et 3S]+[Tf 2N]–)
28−0.062
−1.347
2.716
−1.350
−5.274
3.242
310.097
([3-M
BPy]+[Trif]–)
29−0.088
−0.110
1.121
0.330
−5.188
3.310
360.121
([MEIm]+[B(CN) 4]–)
30−0.151
−0.111
1.141
−0.875
−4.682
3.002
410.118
([HMIm]+[FAP
]–)
310.067
0.150
0.254
−2.530
−4.014
3.446
840.159
([EMIm]+[FAP
]–)
320.093
0.448
0.027
−2.667
−3.673
3.082
660.163
([1-PrOHPy]+[FAP
]–)
33−0.098
0.294
0.393
−2.160
−2.785
2.961
760.161
([PMPip]
+[Tf 2N]–)
34−0.231
0.453
0.352
−1.263
−4.290
3.401
780.153
([BMPyrr]+[SCN
]–)
35−0.368
0.728
0.624
1.587
−4.715
3.104
640.177
([EMIm]+[M
eSO3]–)
36−0.799
0.493
0.644
2.842
−4.440
3.007
400.189
([MDIm]+[B(CN) 4]–)
370.108
−0.138
0.742
−1.279
−4.667
3.526
420.116
([H3TdP
]+[OtSO4]–)
380.138
−0.077
−0.248
1.073
−5.028
4.037
380.149
([1-PrOHPy]+[Tf 2N]–)
39−0.117
−0.034
1.056
−0.934
−4.147
2.922
450.113
(Con
tinued)
PHYSICS AND CHEMISTRY OF LIQUIDS 3
Table1.
(Con
tinued).
Ionicliquid
SolvNo.
ce
sa
bv/l
NSD
([BMPyrr]+[B(CN) 4]–)
40−0.071
0.354
0.562
−1.030
−4.415
3.346
800.139
([BMPip]
+[Tf 2N]–)
41−0.129
0.494
0.235
−1.165
−4.385
3.422
780.162
([BMIm]+[BETI]–)
420.023
0.083
0.334
−1.701
−4.236
3.041
510.110
([BMIm]+[N(CN) 2]–)
43−0.272
0.448
0.722
1.103
−4.437
3.131
670.118
([BMPyrr]+[FAP
]–)
440.100
0.227
0.392
−2.607
−4.285
3.245
900.156
([BMPyrr]+[Trif]–)
45−0.366
0.448
0.628
0.362
−4.469
3.327
650.134
([MHIm]+[B(CN) 4]–)
460.000
0.119
0.730
−1.083
−4.431
3.389
560.108
([MeoeM
Pip]
+[Tf 2N]–)
47−0.068
0.126
0.726
−1.122
−4.642
3.276
590.118
([MeoeM
Morp]
+[FAP
]–)
480.000
0.000
0.830
−2.362
−4.022
3.064
990.164
([MeoeM
Morp]
+[Tf 2N]–)
49−0.188
0.094
0.918
−1.180
−4.346
3.043
620.119
([MeoeM
Pyrr]+[FAP
]–)
500.130
0.168
0.477
−2.483
−4.245
3.215
102
0.158
([MeoeM
Pip]
+[FAP
]–)
510.114
0.260
0.391
−2.448
−4.245
3.281
103
0.163
([BMPyrr]+[C(CN) 3]–)
52−0.126
0.430
0.398
0.000
−4.563
3.333
950.120
([MeoeM
2EAm
]+[FAP
]–)
530.034
0.119
0.628
−2.408
−4.070
3.156
105
0.149
([EtOHMIm]+[FAP
]–)
540.000
0.111
0.490
−2.383
−2.523
2.858
102
0.140
([MBIm]+[TDI]–)
55−0.032
0.099
0.616
−0.254
−4.499
3.496
660.107
([3-M
BPy]+[TDI]–)
56−0.062
0.278
0.544
−0.833
−4.517
3.586
660.113
[(H3TdP
]+[L-Lact]–)
570.000
0.000
0.000
3.241
−5.329
4.158
310.158
[(H3TdP
]+[+CS]–)
580.000
0.000
0.229
2.749
−5.343
4.555
400.125
([MB 3Am
]+[Tf 2N]–)
59−0.233
0.000
0.404
−1.313
−4.542
3.687
440.113
([OM3Am]+[Tf 2N]–)
60−0.165
−0.181
0.569
−1.419
−4.677
3.711
440.123
([DM3Am]+[Tf 2N]–)
61−0.128
−0.131
0.329
−1.458
−4.550
3.816
460.132
[(O4Am]+[Tf 2N]–)
620.226
0.000
−0.212
−1.756
−4.739
3.825
420.164
([PMPyrr]+[Tf 2N]–)
63−0.236
0.000
0.908
−1.015
−4.691
3.446
390.143
([BMPyrr]+[Tf 2N]–)
64−0.269
0.000
0.747
−1.094
−4.594
3.512
430.133
([PeM
Pyrr]+[Tf 2N]–)
65−0.303
0.000
0.727
−1.107
−4.622
3.630
420.132
([HMPyrr]+[Tf 2N]–)
66−0.226
−0.083
0.560
−1.301
−4.501
3.673
360.123
([OMPyrr]+[Tf 2N]–)
67−0.253
0.000
0.520
−1.460
−4.696
3.815
370.102
([DMPyrr]+[Tf 2N]–)
68−0.083
−0.142
0.419
−1.467
−4.859
3.824
400.108
([QUIN6]+[Tf 2N]–)
69−0.360
0.138
0.594
−0.936
−4.776
3.864
430.133
([QUIN8]+[Tf 2N]–)
70−0.149
0.000
0.451
−1.080
−4.886
3.861
430.133
([BM2Im]+[Tf 2N]–)
71−0.347
0.111
0.718
−1.195
−4.418
3.502
600.121
([4-CNBPy]+[Tf 2N]–)
72−0.316
0.132
1.015
−1.040
−4.399
3.272
640.123
([4-M
BPy]+[C(CN) 3]–)
73−0.800
0.910
2.100
2.350
2.070
2.990
330.170
([MBIm]+[C(CN) 3]–)
74−0.700
0.730
2.030
1.930
1.640
2.780
330.120
Gas-to-ionicliquidsolvent
([MBIm]+[Tf 2N]–)
1−0.394
0.089
1.969
2.283
0.873
0.696
104
0.111
([MHIm]+[Tf 2N]–)
2−0.384
−0.240
2.060
2.184
0.561
0.754
770.117
([M3BAm
]+[Tf 2N]–)
3−0.457
0.000
2.188
2.375
0.663
0.668
580.120
([MOIm]+[BF 4]–)
4−0.409
−0.049
1.562
2.911
0.803
0.778
610.140
(Con
tinued)
4 B. JIANG ET AL.
Table1.
(Con
tinued).
Ionicliquid
SolvNo.
ce
sa
bv/l
NSD
([MBIm]+[PF 6]–)
5−0.460
−0.191
2.747
2.228
0.363
0.663
910.154
([4-M
BPy]+[BF 4]–)
6−0.611
0.487
2.484
3.190
0.558
0.606
380.062
([MBIm]+[BF 4]–)
7−0.600
0.356
2.534
3.312
0.284
0.604
660.099
([MEIm]+[EtSO4]
–)
8−0.709
0.137
2.544
5.262
0.042
0.592
490.104
([MEIm]+[Tf 2N]–)
9−0.486
0.068
2.296
2.278
0.988
0.651
650.094
([M2EIm]+[Tf 2N]–)
10−0.565
0.214
2.347
2.075
0.896
0.655
380.071
([4-M
BPy]+[Tf 2N]–)
11−0.522
−0.113
2.777
2.673
0.122
0.741
370.080
([MBIm]+[OtSO4]–)
12−0.288
−0.287
1.940
4.862
−0.302
0.880
560.116
([PM2Im]+[BF 4]–)
13−1.025
0.997
2.728
4.525
0.518
0.458
340.126
([MBIm]+[Trif]–)
14−0.649
0.164
2.278
3.850
0.552
0.694
520.105
([D2M
Im]+[Tf 2N]–)
15−0.252
−0.269
1.603
1.946
0.354
0.856
400.082
([MOIm]+[PF 6]–)
16−0.118
−0.130
1.535
2.146
1.025
0.703
480.142
([EtOHMIM]+[Tf 2N]–)
17−0.793
0.139
2.404
2.587
1.353
0.581
810.100
([EtOHMIM]+[PF 6]–)
18−1.044
−0.042
3.092
3.116
1.189
0.508
370.125
([HexM3Am]+[Tf 2N]–)
19−0.469
−0.058
2.085
2.185
0.617
0.689
930.128
([EMIm]+[N(CN) 2]–)
20−0.990
0.379
2.880
4.789
0.421
0.617
750.114
[(Hexom
) 2Im]+[Tf 2N]–)
21−0.314
−0.479
2.076
2.376
0.287
0.835
340.050
([Hexom
MIm]+[Tf 2N]–)
22−0.462
−0.397
2.486
2.428
0.333
0.785
340.050
([CNPrMIm]+[N(CN) 2]–)
23−1.489
−0.418
3.089
4.807
0.626
0.644
450.121
([MeoeM
Im]+[Tf 2N]–)
24−0.509
0.065
2.476
2.271
0.671
0.603
520.108
([(Meo) 2Im]+[Tf 2N]–)
25−0.762
−0.013
2.557
2.427
1.157
0.584
480.084
([MEIm]+[E2PO4]–)
26−0.412
0.195
2.237
7.432
−0.091
0.714
380.135
([H3TdP
]+[Tf 2N]–)
27−0.406
−0.576
1.602
2.338
−0.009
0.959
590.112
([Et 3S]+[Tf 2N]–)
28−0.606
−0.196
2.992
2.444
0.355
0.690
310.055
([3-M
BPy]+[Trif]–)
29−0.564
0.035
2.697
3.977
−0.050
0.699
360.070
([MEIm]+[B(CN) 4]–)
30−0.407
0.141
2.743
2.783
0.469
0.625
410.061
([HMIm]+[FAP
]–)
31−0.189
−0.086
2.077
1.090
0.844
0.696
840.122
([EMIm]+[FAP
]–)
32−0.290
0.053
2.123
1.106
0.997
0.617
690.150
([1-PrOHPy]+[FAP
]–)
33−0.448
0.096
2.467
1.563
1.898
0.563
770.136
([PMPip]
+[Tf 2N]–)
34−0.432
0.145
2.287
2.489
0.402
0.674
790.126
([BMPyrr]+[SCN
]–)
35−0.686
0.543
2.622
5.352
0.000
0.602
650.130
([EMIm]+[M
eSO3]–)
36−1.398
0.485
2.562
6.616
0.495
0.642
420.153
([MDIm]+[B(CN) 4]–)
37−0.335
−0.176
2.388
2.421
0.372
0.772
420.050
([H3TdP
]+[OtSO4]–)
38−0.181
−0.320
1.361
4.749
0.000
0.902
390.129
([1-PrOHPy]+[Tf 2N]–)
39−0.630
0.316
2.587
2.758
1.025
0.583
450.061
([BMPyrr]+[B(CN) 4]–)
40−0.387
0.057
2.498
2.686
0.343
0.688
810.093
([BMPip]
+[Tf 2N]–)
41−0.347
0.111
2.242
2.472
0.294
0.687
790.119
([BMIm]+[BETI]–)
42−0.460
0.141
2.206
1.980
0.696
0.613
530.093
([BMIm]+[N(CN) 2]–)
43−0.773
0.435
2.553
4.844
0.505
0.658
670.082
([BMPyrr]+[FAP
]–)
44−0.196
0.000
2.288
1.078
0.505
0.649
900.127
(Con
tinued)
PHYSICS AND CHEMISTRY OF LIQUIDS 5
Table1.
(Con
tinued).
Ionicliquid
SolvNo.
ce
sa
bv/l
NSD
([BMPyrr]+[Trif]–)
45−0.681
0.177
2.553
4.092
0.283
0.677
660.089
([MHIm]+[B(CN) 4]–)
46−0.373
−0.022
2.559
2.594
0.450
0.711
560.069
([MeoeM
Pip]
+[Tf 2N]–)
47−0.453
0.075
2.519
2.535
0.279
0.672
590.078
([MeoeM
Morp]
+[FAP
]–)
48−0.364
0.000
2.645
1.319
0.887
0.595
990.140
([MeoeM
Morp]
+[Tf 2N]–)
49−0.648
0.142
2.748
2.475
0.594
0.614
620.092
([MeoeM
Pyrr]+[FAP
]–)
50−0.145
0.000
2.360
1.248
0.523
0.629
104
0.137
([MeoeM
Pip]
+[FAP
]–)
51−0.177
0.000
2.311
1.249
0.542
0.655
103
0.137
([BMPyrr]+[C(CN) 3]–)
52−0.461
0.214
2.497
3.701
0.243
0.684
960.080
([MeoeM
2EAm
]+[FAP
]–)
53−0.321
−0.071
2.557
1.329
0.722
0.631
106
0.128
([EtOHMIm]+[FAP
]–)
54−0.400
0.000
2.494
1.340
2.272
0.542
102
0.120
([MBIm]+[TDI]–)
55−0.432
−0.044
2.366
3.466
0.438
0.752
660.067
([3-M
BPy]+[TDI]–)
56−0.419
0.104
2.269
3.367
0.413
0.772
660.069
[(H3TdP
]+[L-Lact]–)
57−0.191
−0.353
1.622
6.653
−0.332
0.907
310.135
[(H3TdP
]+[+CS]–)
58−0.201
−0.408
1.727
6.367
−0.241
1.035
400.118
([MB 3Am
]+[Tf 2N]–)
59−0.506
−0.169
2.103
2.298
0.412
0.777
440.083
([OM3Am]+[Tf 2N]–)
60−0.426
−0.338
2.242
2.195
0.684
0.779
440.092
([DM3Am]+[Tf 2N]–)
61−0.363
−0.339
1.986
2.144
0.422
0.809
460.102
[(O4Am]+[Tf 2N]–)
620.000
−0.287
1.478
1.845
0.189
0.816
420.124
([PMPyrr]+[Tf 2N]–)
63−0.466
0.000
2.562
2.505
0.271
0.682
390.116
([BMPyrr]+[Tf 2N]–)
64−0.522
0.000
2.388
2.446
0.381
0.711
430.099
([PeM
Pyrr]+[Tf 2N]–)
65−0.549
0.000
2.317
2.425
0.385
0.747
420.097
([HMPyrr]+[Tf 2N]–)
66−0.533
−0.110
2.146
2.278
0.650
0.767
360.088
([OMPyrr]+[Tf 2N]–)
67−0.587
−0.064
2.080
2.176
0.486
0.822
370.080
([DMPyrr]+[Tf 2N]–)
68−0.395
−0.241
1.991
2.112
0.268
0.822
400.063
([QUIN6]+[Tf 2N]–)
69−0.562
−0.071
2.201
2.569
0.238
0.815
430.103
([QUIN8]+[Tf 2N]–)
70−0.363
−0.186
2.048
2.430
0.142
0.816
430.100
([BM2Im]+[Tf 2N]–)
71−0.641
0.000
2.429
2.663
0.521
0.721
600.085
([4-CNBPy]+[Tf 2N]–)
72−0.768
0.086
2.810
2.685
0.553
0.691
640.091
([4-M
BPy]+[C(CN) 3]–)
73−0.620
0.510
2.300
3.420
0.530
0.720
350.200
([MBIm]+[C(CN) 3]–)
74−0.780
0.365
2.380
3.325
0.740
0.664
350.170
([PeM
Pip]
+[Tf 2N]–)
75−0.477
−0.186
2.639
2.450
0.103
0.761
410.075
([HMPip]
+[Tf 2N]–)
76−0.404
−0.245
2.469
2.348
0.075
0.775
420.066
6 B. JIANG ET AL.
Table 2. Names and abbreviations of the various cations and anions contained in the differentionic liquid solvents.
In other words, the lowercase equation coefficients now become cation-specific and anion-specificnumerical values, which can then be combined as a cation–anion sum to yield Abraham modelequation coefficients that would be specific for the one IL solvent containing the given cation–anion pair combination. In some respects the treatment proposed by Sprunger and co-workers isanalogous to estimating each of the different Abraham model equation coefficients by a groupcontribution or fragment group method, where the entire cation serves as one functional group inthe IL and the entire counter-anion defines the second functional group.
To date we have reported ion-specific equation coefficients for 45 different cations and 19different anions. The most updated set of ion-specific equation coefficients was publishedapproximately 2 years ago.[41] Since the last update was published, we have calculated ion-specific equation coefficients for five additional cations: 1-butyl-2,3-dimethylimidazolium,[42] 4-cyano-1-butylpyridinium,[42] 2-methoxyethyl(dimethyl)ethylammonium,[43] 1-hexylquinuclidi-nium,[21] 1-octylquinuclidinium [21] and for three additional anions: L-lactate,[44] (1S)-(+)-10-camphorsulphonate,[44] and 4,5-dicyano-2-(trifluoromethyl)imidazolide.[45] The 45 differentcation and 19 different anion equation coefficients that we have determined can be combinedto give Abraham model correlations for predicting log K and log P values for 855 (45 × 19)different IL solvents. This is significantly more IL solvents than the 76 IL solvents listed in Table 1for which we have IL-specific Abraham model correlations. Through standard thermodynamicrelationships, the predicted log K and log P values can be converted first to infinite dilutionactivity coefficients, γ1solute:
logK ¼ log P þ logKW ¼ logRT
γ1solutePosoluteVsolvent
� �(5)
and then to separation factors, S11;2:
S11;2 ¼γ1solute1γ1solute2
(6)
that can be used to determine whether or not a desired chemical separation can be achieved using aparticular IL solvent. In Equation (5), R is the universal gas constant,Vsolvent is themolar volume of theIL solvent, Po
soluteis the vapour pressure of the solute at the system temperature, T is the systemtemperature, and log Kw is the logarithm of the solute’s gas-to-water partition coefficient. In thepresent communication we have determined Abraham model correlations from published γ1solute andlog K data for solutes dissolved in 1-allyl-3-methylimidazolium dicyanamide ([AllMIm]+[N(CN)2]
–)[49] and 1-butyl-1-methylmorpholiniumtricyanomethanide ([BMMorp]+[C(CN)3]
–).[50] Also calculated as part of this study are the ion-specific equation coefficients for [AllMIm]+, [OE3Am]+, [B3EP]
+ and [BMMorp]+ cations.
2. Computation methodology and the partition coefficient data sets
The Abraham model has been successfully used to correlate solute transfer processes. The transferprocess might involve solute partitioning between two immiscible (or partly immiscible) phases aswould be the case for solvent extractions, or might involve solute transfer where the two phasesare physically separated from each other. The latter would be referred to as a hypotheticalpartition coefficient where the numerical value would be calculable as either a solubility ratio orthrough a thermodynamic cycle, such as water-to-organic solvent partition coefficient equals thegas-to-organic solvent partition coefficient divided by the gas-to-water partition coefficient(P = K/Kw). A major difference between the two types of solute transfer processes is that firstinvolves mutually saturated phases, while the second involves the ‘neat’ liquid solvents. The water-to-IL solvent partitioning systems that are listed in Table 1 all pertain to solute transfer into neatIL solvents that are not saturated with water.
The data sets for ([AllMIm]+[N(CN)2]–), ([AllMIm]+[Tf2N]
–), ([OE3Am]+[Tf2N]–),
([B3EP]+[E2PO4]
–) and ([BMMorp]+[C(CN)3]–) were constructed from published partition coeffi-
cient data for solutes dissolved in the anhydrous IL solvents. For each IL solvent the partitioncoefficient measurements were performed at several temperatures slightly higher than 298.15 K. Thenumerical log K (at 298.15 K) values used in the present study were calculated from the standardthermodynamic log K vs. 1/T linear relationship based on the measured values at either 318.15 and328,15 K for ([AllMIm]+[Tf2N]
–), ([OE3Am]+[Tf2N]–) and ([BMMorp]+[C(CN)3]
–), or 328.15 and338.15 K for ([B3EP]
+[E2PO4]–), or 308.15 and 318.15 K for ([AllMIm]+[N(CN)2]
–). The foremen-tioned temperatures were the two lowest temperatures that were studied for each of the four ILsolvents. The linear extrapolation should be valid as the measurements were performed at tempera-tures not too far removed from the desired temperature of 298.15 K (about 40 K in the worst case).The respective log P values for each solute–IL combination were calculated by subtracting log Kw
from the extrapolated log K values as indicated in Equation (5).The calculated log K and log P values at 298.15 K are assembled in Tables 3–7 for solutes
dissolved in ([AllMIm]+[N(CN)2]–), ([AllMIm]+[Tf2N]
–), ([B3EP]+[E2PO4]
–), ([OE3Am]+[Tf2N]–)
and ([BMMorp]+[C(CN)3]–), respectively. Each data set contains between 49 and 63 chemically
diverse organic liquid solutes. The list of organic solutes includes alkanes, alkenes, alkynes,aromatic and heterocyclic compounds, primary and secondary alcohols, dialkyl ethers and cyclicethers, alkanones, alkyl alkanoates, and nitroalkanes. We searched the published literature but wasunable to find partition coefficient or solubility data for gaseous or solid solutes in the five ILsolvents. Also collected in Tables 3–7 are the numerical solute descriptors for the organiccompounds studied in the present investigation. Numerical values of the solute descriptors inour database are of experimental origin and are based on observed solubility data and Henry’s lawconstants,[51–54] on measured gas–liquid and high-performance liquid chromatographic reten-tion times and retention factors,[55,56] and on experimental practical partition coefficient mea-surements for the equilibrium solute distribution between water and an immiscible (or partiallymiscible) organic solvent.[57]
Calculation of the Abraham model IL-specific equation coefficients is relatively straightforwardand begins with writing a log K and log P equation for each solute–IL solvent pair. For eachequation the measured log K and log P values, as well as the five solute descriptors that appear onthe right-hand side of Equations (1) and (2), are known. This leaves only the six unknownequation coefficients that must be calculated. The resulting set of log K equations are solved
PHYSICS AND CHEMISTRY OF LIQUIDS 9
Table3.
Logarithm
ofgas-to-anh
ydrous
ILpartition
coefficient,log
K,andlogarithm
ofwater-to-anhydrou
sILpartition
coefficient,log
P,fororganicsolutesdissolvedin
([AllM
Im]+[N(CN) 2]–)at
298K.
Solute
ES
AB
LV
logK
logP
Pentane
0.000
0.000
0.000
0.000
2.162
0.8131
0.249
1.949
Hexane
0.000
0.000
0.000
0.000
2.668
0.9540
0.501
2.321
3-Methylpentane
0.000
0.000
0.000
0.000
2.581
0.9540
0.487
2.327
2,2-Dimethylbutane
0.000
0.000
0.000
0.000
2.352
0.9540
0.294
2.134
Heptane
0.000
0.000
0.000
0.000
3.173
1.0949
0.772
2.732
Octane
0.000
0.000
0.000
0.000
3.677
1.2358
1.041
3.151
2,2,4-Trimethylpentane
0.000
0.000
0.000
0.000
3.106
1.2358
0.664
2.784
Non
ane
0.000
0.000
0.000
0.000
4.182
1.3767
1.315
3.465
Decane
0.000
0.000
0.000
0.000
4.686
1.5176
1.600
3.920
Cyclop
entane
0.263
0.100
0.000
0.000
2.477
0.7045
0.845
1.725
Cycloh
exane
0.305
0.100
0.000
0.000
2.964
0.8454
1.105
2.005
Methylcyclohexane
0.244
0.060
0.000
0.000
3.319
0.9863
1.198
2.448
Cycloh
eptane
0.350
0.100
0.000
0.000
3.704
0.9863
1.875
2.455
Cyclooctane
0.413
0.100
0.000
0.000
4.329
1.1272
2.011
2.781
1-Pentene
0.093
0.080
0.000
0.070
2.047
0.7701
0.581
1.811
1-Hexene
0.078
0.080
0.000
0.070
2.572
0.9110
0.862
2.022
Cycloh
exene
0.395
0.280
0.000
0.090
2.952
0.8204
1.576
1.846
1-Heptene
0.092
0.080
0.000
0.070
3.063
1.0519
1.109
2.329
1-Octene
0.094
0.080
0.000
0.070
3.568
1.1928
1.371
2.781
1-Decene
0.093
0.080
0.000
0.070
4.554
1.4746
1.868
3.508
1-Pentyne
0.172
0.230
0.120
0.120
2.010
0.7271
1.471
1.481
1-Hexyne
0.166
0.220
0.100
0.120
2.510
0.8680
1.741
1.951
1-Heptyne
0.160
0.230
0.120
0.100
3.000
1.0089
1.985
2.425
1-Octyne
0.155
0.220
0.090
0.100
3.521
1.1498
2.230
2.750
Benzene
0.610
0.520
0.000
0.140
2.786
0.7164
2.425
1.795
Toluene
0.601
0.520
0.000
0.140
3.325
0.8573
2.703
2.053
Ethylbenzene
0.613
0.510
0.000
0.150
3.778
0.9982
2.889
2.309
o-Xylene
0.663
0.560
0.000
0.160
3.939
0.9982
3.169
2.509
m-Xylene
0.623
0.520
0.000
0.160
3.839
0.9982
2.963
2.353
p-Xylene
0.613
0.520
0.000
0.160
3.839
0.9982
2.973
2.383
Prop
ylbenzene
0.604
0.500
0.000
0.150
4.230
1.1391
3.058
2.668
Isop
ropylbenzene
0.602
0.490
0.000
0.160
4.084
1.1391
2.963
2.523
Styrene
0.849
0.650
0.000
0.160
3.908
0.9550
3.434
2.484
α-Methylstyrene
0.851
0.640
0.000
0.190
4.290
1.0960
3.608
2.648
Methano
l0.278
0.440
0.430
0.470
0.970
0.3082
3.059
−0.681
Ethano
l0.246
0.420
0.370
0.480
1.485
0.4491
3.094
−0.576
1-Prop
anol
0.236
0.420
0.370
0.480
2.031
0.5900
3.362
−0.198
2-Prop
anol
0.212
0.360
0.330
0.560
1.764
0.5900
2.996
−0.484
1-Bu
tano
l0.224
0.420
0.370
0.480
2.601
0.7309
3.650
0.190
(Con
tinued)
10 B. JIANG ET AL.
Table3.
(Con
tinued).
Solute
ES
AB
LV
logK
logP
2-Bu
tano
l0.217
0.360
0.330
0.560
2.338
0.7309
3.254
−0.136
2-Methyl-1-propano
l0.217
0.390
0.370
0.480
2.413
0.7309
3.456
0.156
tert-Butanol
0.180
0.300
0.310
0.600
1.963
0.7309
2.897
−0.383
1-Pentanol
0.219
0.420
0.370
0.480
3.106
0.8718
3.921
0.571
Thioph
ene
0.687
0.570
0.000
0.150
2.819
0.6411
2.746
1.706
Tetrahydrofuran
0.289
0.520
0.000
0.480
2.636
0.6223
2.343
−0.207
1,4-Dioxane
0.329
0.750
0.000
0.640
2.892
0.6810
3.187
−0.523
Methyltert-bu
tyle
ther
0.024
0.220
0.000
0.550
2.372
0.8718
1.408
−0.212
Ethyltert-bu
tyle
ther
−0.020
0.180
0.000
0.590
2.699
1.0127
1.213
−0.057
Methyltert-am
ylether
0.050
0.210
0.000
0.600
2.916
1.0127
1.675
0.205
Diethylether
0.041
0.250
0.000
0.450
2.015
0.7309
1.132
−0.038
Dipropyle
ther
0.008
0.250
0.000
0.450
2.954
1.0127
1.426
0.536
Diisop
ropyle
ther
−0.063
0.170
0.000
0.570
2.501
1.0127
1.077
0.027
Dibutylether
0.000
0.250
0.000
0.450
3.924
1.2945
1.909
1.219
Aceton
e0.179
0.700
0.040
0.490
1.696
0.5470
2.450
−0.340
2-Pentanon
e0.143
0.680
0.000
0.510
2.755
0.8288
2.812
0.232
3-Pentanon
e0.154
0.660
0.000
0.510
2.811
0.8288
2.786
0.286
Methylacetate
0.142
0.640
0.000
0.450
1.911
0.6057
2.249
−0.051
Ethylacetate
0.106
0.620
0.000
0.450
2.314
0.7466
2.341
0.181
Methylp
ropano
ate
0.128
0.600
0.000
0.450
2.431
0.7470
2.417
0.267
Methylb
utanoate
0.106
0.600
0.000
0.450
2.943
0.8880
2.604
0.524
Butanal
0.187
0.650
0.000
0.450
2.270
0.6880
2.452
0.122
Aceton
itrile
0.237
0.900
0.070
0.320
1.739
0.4042
2.996
0.146
Pyrid
ine
0.631
0.840
0.000
0.520
3.022
0.6750
3.463
0.023
1-Nitrop
ropane
0.242
0.950
0.000
0.310
2.894
0.7055
3.587
1.137
Water
0.000
0.600
0.590
0.460
0.245
0.1673
3.938
−0.752
PHYSICS AND CHEMISTRY OF LIQUIDS 11
Table4.
Logarithm
ofgas-to-anh
ydrous
ILpartition
coefficient,log
K,andlogarithm
ofwater-to-anhydrou
sIL
partition
coefficient,log
P,fororganicsolutesdissolvedin
([AllM
Im]+[Tf 2N]–)at
298K.
Solute
ES
AB
LV
logK
logP
Hexane
0.000
0.000
0.000
0.000
2.668
0.9540
1.266
3.086
3-Methylpentane
0.000
0.000
0.000
0.000
2.581
0.9540
1.255
3.095
2,2-Dimethylbutane
0.000
0.000
0.000
0.000
2.352
0.9540
1.086
2.926
Heptane
0.000
0.000
0.000
0.000
3.173
1.0949
1.601
3.561
Octane
0.000
0.000
0.000
0.000
3.677
1.2358
1.921
4.031
2,2,4-Trimethylpentane
0.000
0.000
0.000
0.000
3.106
1.2358
1.595
3.715
Non
ane
0.000
0.000
0.000
0.000
4.182
1.3767
2.245
4.395
Decane
0.000
0.000
0.000
0.000
4.686
1.5176
2.554
4.874
Cyclop
entane
0.263
0.100
0.000
0.000
2.477
0.7045
1.360
2.240
Cycloh
exane
0.305
0.100
0.000
0.000
2.964
0.8454
1.702
2.602
Methylcyclohexane
0.244
0.060
0.000
0.000
3.319
0.9863
1.873
3.123
Cycloh
eptane
0.350
0.100
0.000
0.000
3.704
0.9863
2.199
2.779
Cyclooctane
0.413
0.100
0.000
0.000
4.329
1.1272
2.635
3.405
1-Pentene
0.093
0.080
0.000
0.070
2.047
0.7701
1.180
2.410
1-Hexene
0.078
0.080
0.000
0.070
2.572
0.9110
1.509
2.669
Cycloh
exene
0.395
0.280
0.000
0.090
2.952
0.8204
2.029
2.299
1-Heptene
0.092
0.080
0.000
0.070
3.063
1.0519
1.830
3.050
1-Octene
0.094
0.080
0.000
0.070
3.568
1.1928
2.169
3.579
1-Decene
0.093
0.080
0.000
0.070
4.554
1.4746
2.785
4.425
1-Pentyne
0.172
0.230
0.120
0.120
2.010
0.7271
1.828
1.838
1-Hexyne
0.166
0.220
0.100
0.120
2.510
0.8680
2.167
2.377
1-Heptyne
0.160
0.230
0.120
0.100
3.000
1.0089
2.493
2.933
1-Octyne
0.155
0.220
0.090
0.100
3.521
1.1498
2.820
3.340
Benzene
0.610
0.520
0.000
0.140
2.786
0.7164
2.833
2.203
Toluene
0.601
0.520
0.000
0.140
3.325
0.8573
3.186
2.536
Ethylbenzene
0.613
0.510
0.000
0.150
3.778
0.9982
3.445
2.865
o-Xylene
0.663
0.560
0.000
0.160
3.939
0.9982
3.686
3.026
m-Xylene
0.623
0.520
0.000
0.160
3.839
0.9982
3.523
2.913
p-Xylene
0.613
0.520
0.000
0.160
3.839
0.9982
3.514
2.924
Prop
ylbenzene
0.604
0.500
0.000
0.150
4.230
1.1391
3.709
3.319
Isop
ropylbenzene
0.602
0.490
0.000
0.160
4.084
1.1391
3.600
3.160
Styrene
0.849
0.650
0.000
0.160
3.908
0.9550
3.914
2.964
α-Methylstyrene
0.851
0.640
0.000
0.190
4.290
1.0960
4.102
3.142
Methano
l0.278
0.440
0.430
0.470
0.970
0.3082
2.563
−1.177
Ethano
l0.246
0.420
0.370
0.480
1.485
0.4491
2.773
−0.897
1-Prop
anol
0.236
0.420
0.370
0.480
2.031
0.5900
3.114
−0.446
2-Prop
anol
0.212
0.360
0.330
0.560
1.764
0.5900
2.835
−0.645
1-Bu
tano
l0.224
0.420
0.370
0.480
2.601
0.7309
3.474
0.014
2-Bu
tano
l0.217
0.360
0.330
0.560
2.338
0.7309
3.141
−0.249
(Con
tinued)
12 B. JIANG ET AL.
Table4.
(Con
tinued).
Solute
ES
AB
LV
logK
logP
2-Methyl-1-propano
l0.2170
0.390
0.370
0.480
2.413
0.7309
3.293
−0.007
tert-Butanol
0.180
0.300
0.310
0.600
1.963
0.7309
2.865
−0.415
1-Pentanol
0.219
0.420
0.370
0.480
3.106
0.8718
3.822
0.472
Thioph
ene
0.687
0.570
0.000
0.150
2.819
0.6411
2.958
1.918
Tetrahydrofuran
0.289
0.520
0.000
0.480
2.636
0.6223
2.808
0.258
1,4-Dioxane
0.329
0.750
0.000
0.640
2.892
0.6810
3.575
−0.135
Methyltert-bu
tyle
ther
0.024
0.220
0.000
0.550
2.372
0.8718
2.097
0.477
Ethyltert-bu
tyle
ther
−0.020
0.180
0.000
0.590
2.699
1.0127
2.013
0.743
Methyltert-am
ylether
0.050
0.210
0.000
0.600
2.916
1.0127
2.427
0.957
Diethylether
0.041
0.250
0.000
0.450
2.015
0.7309
1.750
0.580
Dipropyle
ther
0.008
0.250
0.000
0.450
2.954
1.0127
2.196
1.306
Diisop
ropyle
ther
−0.063
0.170
0.000
0.570
2.501
1.0127
1.917
0.867
Dibutylether
0.000
0.250
0.000
0.450
3.924
1.2945
2.813
2.123
Aceton
e0.179
0.700
0.040
0.490
1.696
0.5470
2.913
0.123
2-Pentanon
e0.143
0.680
0.000
0.510
2.755
0.8288
3.446
0.866
3-Pentanon
e0.154
0.660
0.000
0.510
2.811
0.8288
3.421
0.921
Methylacetate
0.142
0.640
0.000
0.450
1.911
0.6057
2.751
0.451
Ethylacetate
0.106
0.620
0.000
0.450
2.314
0.7466
2.975
0.815
Methylp
ropano
ate
0.128
0.600
0.000
0.450
2.431
0.7470
3.021
0.871
Methylb
utanoate
0.106
0.600
0.000
0.450
2.943
0.8880
3.278
1.198
Butanal
0.187
0.650
0.000
0.450
2.270
0.6880
2.948
0.618
Aceton
itrile
0.237
0.900
0.070
0.320
1.739
0.4042
3.265
0.415
Pyrid
ine
0.631
0.840
0.000
0.520
3.022
0.6750
3.804
0.364
1-Nitrop
ropane
0.242
0.950
0.000
0.310
2.894
0.7055
3.987
1.537
Water
0.000
0.600
0.590
0.460
0.245
0.1673
2.731
−1.959
PHYSICS AND CHEMISTRY OF LIQUIDS 13
Table5.
Logarithm
ofgas-to-anh
ydrous
ILpartition
coefficient,log
K,andlogarithm
ofwater-to-anhydrou
sILpartition
coefficient,log
P,foro
rganicsolutesdissolvedin([B
3EP]
+[E2PO4]–)at2
98K.
Solute
ES
AB
LV
logK
logP
Pentane
0.000
0.000
0.000
0.000
2.162
0.8131
1.475
3.175
Hexane
0.000
0.000
0.000
0.000
2.668
0.9540
1.929
3.749
3-Methylpentane
0.000
0.000
0.000
0.000
2.581
0.9540
1.864
3.704
2,2-Dimethylbutane
0.000
0.000
0.000
0.000
2.352
0.9540
1.617
3.457
Heptane
0.000
0.000
0.000
0.000
3.173
1.0949
2.357
4.317
Octane
0.000
0.000
0.000
0.000
3.677
1.2358
2.794
4.904
2,2,4-Trimethylpentane
0.000
0.000
0.000
0.000
3.106
1.2358
2.287
4.407
Non
ane
0.000
0.000
0.000
0.000
4.182
1.3767
3.206
5.356
Decane
0.000
0.000
0.000
0.000
4.686
1.5176
3.619
5.939
Cyclop
entane
0.263
0.100
0.000
0.000
2.477
0.7045
1.888
2.768
Cycloh
exane
0.305
0.100
0.000
0.000
2.964
0.8454
2.312
3.212
Methylcyclohexane
0.244
0.060
0.000
0.000
3.319
0.9863
2.557
3.807
Cycloh
eptane
0.350
0.100
0.000
0.000
3.704
0.9863
2.899
3.479
Cyclooctane
0.413
0.100
0.000
0.000
4.329
1.1272
3.422
4.192
1-Pentene
0.093
0.080
0.000
0.070
2.047
0.7701
1.532
2.762
1-Hexene
0.078
0.080
0.000
0.070
2.572
0.9110
1.991
3.151
Cycloh
exene
0.395
0.280
0.000
0.090
2.952
0.8204
2.465
2.735
1-Heptene
0.092
0.080
0.000
0.070
3.063
1.0519
2.407
3.627
1-Octene
0.094
0.080
0.000
0.070
3.568
1.1928
2.828
4.238
1-Decene
0.093
0.080
0.000
0.070
4.554
1.4746
3.646
5.286
1-Pentyne
0.172
0.230
0.120
0.120
2.010
0.7271
2.254
2.264
1-Hexyne
0.166
0.220
0.100
0.120
2.510
0.8680
2.697
2.907
1-Heptyne
0.160
0.230
0.120
0.100
3.000
1.0089
3.108
3.548
1-Octyne
0.155
0.220
0.090
0.100
3.521
1.1498
3.545
4.065
Benzene
0.610
0.520
0.000
0.140
2.786
0.7164
2.732
2.102
Toluene
0.601
0.520
0.000
0.140
3.325
0.8573
3.115
2.465
Ethylbenzene
0.613
0.510
0.000
0.150
3.778
0.9982
3.462
2.882
o-Xylene
0.663
0.560
0.000
0.160
3.939
0.9982
3.618
2.958
m-Xylene
0.623
0.520
0.000
0.160
3.839
0.9982
3.483
2.873
p-Xylene
0.613
0.520
0.000
0.160
3.839
0.9982
3.488
2.898
Styrene
0.849
0.650
0.000
0.160
3.908
0.9550
3.892
2.942
Thioph
ene
0.687
0.570
0.000
0.150
2.819
0.6411
3.024
1.984
Tetrahydrofuran
0.289
0.520
0.000
0.480
2.636
0.6223
2.471
−0.079
1,4-Dioxane
0.329
0.750
0.000
0.640
2.892
0.6810
3.039
−0.671
Methyltert-bu
tyle
ther
0.024
0.220
0.000
0.550
2.372
0.8718
1.984
0.364
Ethyltert-bu
tyle
ther
−0.020
0.180
0.000
0.590
2.699
1.0127
2.115
0.845
Methyltert-am
ylether
0.050
0.210
0.000
0.600
2.916
1.0127
2.455
0.985
Diethylether
0.041
0.250
0.000
0.450
2.015
0.7309
1.678
0.508
Dipropyle
ther
0.008
0.250
0.000
0.450
2.954
1.0127
2.432
1.542
Diisop
ropyle
ther
−0.063
0.170
0.000
0.570
2.501
1.0127
2.013
0.963
(Con
tinued)
14 B. JIANG ET AL.
Table5.
(Con
tinued).
Solute
ES
AB
LV
logK
logP
Dibutylether
0.000
0.250
0.000
0.450
3.924
1.2945
3.239
2.549
Aceton
e0.179
0.700
0.040
0.490
1.696
0.5470
2.380
−0.410
2-Pentanon
e0.143
0.680
0.000
0.510
2.755
0.8288
3.097
0.517
3-Pentanon
e0.154
0.660
0.000
0.510
2.811
0.8288
3.092
0.592
2-Hexanon
e0.136
0.680
0.000
0.510
3.286
0.9697
3.530
1.120
3-Hexanon
e0.136
0.660
0.000
0.510
3.271
0.9697
3.419
1.149
Pyrid
ine
0.631
0.840
0.000
0.520
3.022
0.6750
3.618
0.178
1-Nitrop
ropane
0.242
0.950
0.000
0.310
2.894
0.7055
3.987
1.537
Water
0.000
0.600
0.590
0.460
0.245
0.1673
4.344
−0.346
PHYSICS AND CHEMISTRY OF LIQUIDS 15
Table6.
Logarithm
ofgas-to-anh
ydrous
ILpartition
coefficient,log
K,andlogarithm
ofwater-to-anhydrou
sIL
partition
coefficient,log
P,fororganicsolutesdissolvedin
([OE 3Am
]+[Tf 2N]–)at
298K.
Solute
ES
AB
LV
logK
logP
Pentane
0.000
0.000
0.000
0.000
2.162
0.8131
1.300
3.000
Hexane
0.000
0.000
0.000
0.000
2.668
0.9540
1.748
3.568
3-Methylpentane
0.000
0.000
0.000
0.000
2.581
0.9540
1.682
3.522
2,2-Dimethylbutane
0.000
0.000
0.000
0.000
2.352
0.9540
1.438
3.278
Heptane
0.000
0.000
0.000
0.000
3.173
1.0949
2.160
4.120
Octane
0.000
0.000
0.000
0.000
3.677
1.2358
2.558
4.668
2,2,4-Trimethylpentane
0.000
0.000
0.000
0.000
3.106
1.2358
2.126
4.246
Non
ane
0.000
0.000
0.000
0.000
4.182
1.3767
2.960
5.110
Decane
0.000
0.000
0.000
0.000
4.686
1.5176
3.352
5.672
Cyclop
entane
0.263
0.100
0.000
0.000
2.477
0.7045
1.701
2.581
Cycloh
exane
0.305
0.100
0.000
0.000
2.964
0.8454
2.096
2.996
Methylcyclohexane
0.244
0.060
0.000
0.000
3.319
0.9863
2.335
3.585
Cycloh
eptane
0.350
0.100
0.000
0.000
3.704
0.9863
2.649
3.229
Cyclooctane
0.413
0.100
0.000
0.000
4.329
1.1272
3.149
3.919
1-Pentene
0.093
0.080
0.000
0.070
2.047
0.7701
1.437
2.667
1-Hexene
0.078
0.080
0.000
0.070
2.572
0.9110
1.874
3.034
Cycloh
exene
0.395
0.280
0.000
0.090
2.952
0.8204
2.329
2.599
1-Heptene
0.092
0.080
0.000
0.070
3.063
1.0519
2.275
3.495
1-Octene
0.094
0.080
0.000
0.070
3.568
1.1928
2.673
4.083
1-Decene
0.093
0.080
0.000
0.070
4.554
1.4746
3.459
5.099
1-Pentyne
0.172
0.230
0.120
0.120
2.010
0.7271
1.966
1.976
1-Hexyne
0.166
0.220
0.100
0.120
2.510
0.8680
2.370
2.580
1-Heptyne
0.160
0.230
0.120
0.100
3.000
1.0089
2.777
3.217
1-Octyne
0.155
0.220
0.090
0.100
3.521
1.1498
3.170
3.690
Benzene
0.610
0.520
0.000
0.140
2.786
0.7164
2.944
2.314
Toluene
0.601
0.520
0.000
0.140
3.325
0.8573
3.357
2.707
Ethylbenzene
0.613
0.510
0.000
0.150
3.778
0.9982
3.677
3.097
o-Xylene
0.663
0.560
0.000
0.160
3.939
0.9982
3.900
3.240
m-Xylene
0.623
0.520
0.000
0.160
3.839
0.9982
3.765
3.155
p-Xylene
0.613
0.520
0.000
0.160
3.839
0.9982
3.744
3.154
Styrene
0.849
0.650
0.000
0.160
3.908
0.9550
4.114
3.164
α-Methylstyrene
0.851
0.640
0.000
0.190
4.290
1.0960
4.359
3.399
Methano
l0.278
0.440
0.430
0.470
0.970
0.3082
2.372
−1.368
Ethano
l0.246
0.420
0.370
0.480
1.485
0.4491
2.620
−1.050
1-Prop
anol
0.236
0.420
0.370
0.480
2.031
0.5900
3.019
−0.541
2-Prop
anol
0.212
0.360
0.330
0.560
1.764
0.5900
2.730
−0.750
1-Bu
tano
l0.224
0.420
0.370
0.480
2.601
0.7309
3.450
−0.010
2-Bu
tano
l0.217
0.360
0.330
0.560
2.338
0.7309
3.108
−0.282
2-Methyl-1-propano
l0.2170
0.390
0.370
0.480
2.413
0.7309
3.249
−0.051
(Con
tinued)
16 B. JIANG ET AL.
Table6.
(Con
tinued).
Solute
ES
AB
LV
logK
logP
tert-Butanol
0.180
0.300
0.310
0.600
1.963
0.7309
2.804
−0.476
1-Pentanol
0.219
0.420
0.370
0.480
3.106
0.8718
3.869
0.519
Thioph
ene
0.687
0.570
0.000
0.150
2.819
0.6411
3.039
1.999
Tetrahydrofuran
0.289
0.520
0.000
0.480
2.636
0.6223
2.767
0.217
1,4-Dioxane
0.329
0.750
0.000
0.640
2.892
0.6810
3.378
−0.332
Methyltert-bu
tyle
ther
0.024
0.220
0.000
0.550
2.372
0.8718
2.140
0.520
Ethyltert-bu
tyle
ther
−0.020
0.180
0.000
0.590
2.699
1.0127
2.126
0.856
Methyltert-am
ylether
0.050
0.210
0.000
0.600
2.916
1.0127
2.545
1.075
Diethylether
0.041
0.250
0.000
0.450
2.015
0.7309
1.783
0.613
Dipropyle
ther
0.008
0.250
0.000
0.450
2.954
1.0127
2.423
1.533
Diisop
ropyle
ther
−0.063
0.170
0.000
0.570
2.501
1.0127
2.048
0.998
Dibutylether
0.000
0.250
0.000
0.450
3.924
1.2945
3.177
2.487
Aceton
e0.179
0.700
0.040
0.490
1.696
0.5470
2.702
−0.088
2-Pentanon
e0.143
0.680
0.000
0.510
2.755
0.8288
3.404
0.824
3-Pentanon
e0.154
0.660
0.000
0.510
2.811
0.8288
3.403
0.903
Methylacetate
0.142
0.640
0.000
0.450
1.911
0.6057
2.554
0.254
Ethylacetate
0.106
0.620
0.000
0.450
2.314
0.7466
2.861
0.701
Methylp
ropano
ate
0.128
0.600
0.000
0.450
2.431
0.7470
2.923
0.773
Methylb
utanoate
0.106
0.600
0.000
0.450
2.943
0.8880
3.265
1.185
Butanal
0.187
0.650
0.000
0.450
2.270
0.6880
2.885
0.555
Aceton
itrile
0.237
0.900
0.070
0.320
1.739
0.4042
3.006
0.156
Pyrid
ine
0.631
0.840
0.000
0.520
3.022
0.6750
3.730
0.290
1-Nitrop
ropane
0.242
0.950
0.000
0.310
2.894
0.7055
3.882
1.432
Water
0.000
0.600
0.590
0.460
0.245
0.1673
2.456
−2.234
PHYSICS AND CHEMISTRY OF LIQUIDS 17
Table7.
Logarithm
ofgas-to-anh
ydrous
ILpartition
coefficient,log
K,andlogarithm
ofwater-to-anhydrou
sILpartition
coefficient,log
P,fororganicsolutesdissolvedin
([BMMorp]
+[C(CN) 3]–)a
t298K.
Solute
ES
AB
LV
logK
logP
Pentane
0.000
0.000
0.000
0.000
2.162
0.8131
0.519
2.219
Hexane
0.000
0.000
0.000
0.000
2.668
0.9540
0.895
2.715
3-Methylpentane
0.000
0.000
0.000
0.000
2.581
0.9540
0.834
2.674
2,2-Dimethylbutane
0.000
0.000
0.000
0.000
2.352
0.9540
0.551
2.391
Heptane
0.000
0.000
0.000
0.000
3.173
1.0949
1.254
3.214
Octane
0.000
0.000
0.000
0.000
3.677
1.2358
1.574
3.684
2,2,4-Trimethylpentane
0.000
0.000
0.000
0.000
3.106
1.2358
1.119
3.239
Non
ane
0.000
0.000
0.000
0.000
4.182
1.3767
1.909
4.059
Decane
0.000
0.000
0.000
0.000
4.686
1.5176
2.187
4.507
Cyclop
entane
0.263
0.100
0.000
0.000
2.477
0.7045
1.191
2.071
Cycloh
exane
0.305
0.100
0.000
0.000
2.964
0.8454
1.502
2.402
Methylcyclohexane
0.244
0.060
0.000
0.000
3.319
0.9863
1.627
2.857
Cycloh
eptane
0.350
0.100
0.000
0.000
3.704
0.9863
2.058
2.638
Cyclooctane
0.413
0.100
0.000
0.000
4.329
1.1272
2.520
3.290
1-Hexene
0.078
0.080
0.000
0.070
2.572
0.9110
1.261
2.421
Cycloh
exene
0.395
0.280
0.000
0.090
2.952
0.8204
1.958
2.228
1-Heptene
0.092
0.080
0.000
0.070
3.063
1.0519
1.578
2.798
1-Octene
0.094
0.080
0.000
0.070
3.568
1.1928
1.893
3.303
1-Decene
0.093
0.080
0.000
0.070
4.554
1.4746
2.513
4.133
1-Pentyne
0.172
0.230
0.120
0.120
2.010
0.7271
1.732
1.742
1-Hexyne
0.166
0.220
0.100
0.120
2.510
0.8680
2.067
2.277
1-Heptyne
0.160
0.230
0.120
0.100
3.000
1.0089
2.379
2.819
1-Octyne
0.155
0.220
0.090
0.100
3.521
1.1498
2.680
3.200
Benzene
0.610
0.520
0.000
0.140
2.786
0.7164
2.777
2.147
Toluene
0.601
0.520
0.000
0.140
3.325
0.8573
3.116
2.466
Ethylbenzene
0.613
0.510
0.000
0.150
3.778
0.9982
3.364
2.784
o-Xylene
0.663
0.560
0.000
0.160
3.939
0.9982
3.634
2.974
m-Xylene
0.623
0.520
0.000
0.160
3.839
0.9982
3.451
2.841
p-Xylene
0.613
0.520
0.000
0.160
3.839
0.9982
3.443
2.853
Styrene
0.849
0.650
0.000
0.160
3.908
0.9550
3.890
2.940
α-Methylstyrene
0.851
0.640
0.000
0.190
4.290
1.0960
4.065
3.105
Methano
l0.278
0.440
0.430
0.470
0.970
0.3082
2.868
−0.872
Ethano
l0.246
0.420
0.370
0.480
1.485
0.4491
2.994
−0.676
1-Prop
anol
0.236
0.420
0.370
0.480
2.031
0.5900
3.318
−0.242
2-Prop
anol
0.212
0.360
0.330
0.560
1.764
0.5900
2.972
−0.508
1-Bu
tano
l0.224
0.420
0.370
0.480
2.601
0.7309
3.680
0.220
2-Bu
tano
l0.217
0.360
0.330
0.560
2.338
0.7309
3.294
−0.096
2-Methyl-1-propano
l0.2170
0.390
0.370
0.480
2.413
0.7309
3.473
0.173
tert-Butanol
0.180
0.300
0.310
0.600
1.963
0.7309
2.923
−0.357
(Con
tinued)
18 B. JIANG ET AL.
Table7.
(Con
tinued).
Solute
ES
AB
LV
logK
logP
Thioph
ene
0.687
0.570
0.000
0.150
2.819
0.6411
3.043
2.003
Tetrahydrofuran
0.289
0.520
0.000
0.480
2.636
0.6223
2.684
0.134
1,4-Dioxane
0.329
0.750
0.000
0.640
2.892
0.6810
3.537
−0.173
Methyltert-bu
tyle
ther
0.024
0.220
0.000
0.550
2.372
0.8718
1.778
0.158
Ethyltert-bu
tyle
ther
−0.020
0.180
0.000
0.590
2.699
1.0127
1.563
0.293
Methyltert-am
ylether
0.050
0.210
0.000
0.600
2.916
1.0127
2.100
0.630
Diethylether
0.041
0.250
0.000
0.450
2.015
0.7309
1.456
0.286
Dipropyle
ther
0.008
0.250
0.000
0.450
2.954
1.0127
1.882
0.992
Diisop
ropyle
ther
−0.063
0.170
0.000
0.570
2.501
1.0127
1.475
0.425
Dibutylether
0.000
0.250
0.000
0.450
3.924
1.2945
2.464
1.774
Aceton
e0.179
0.700
0.040
0.490
1.696
0.5470
2.711
−0.079
2-Pentanon
e0.143
0.680
0.000
0.510
2.755
0.8288
3.226
0.646
3-Pentanon
e0.154
0.660
0.000
0.510
2.811
0.8288
3.213
0.713
Methylacetate
0.142
0.640
0.000
0.450
1.911
0.6057
2.536
0.236
Ethylacetate
0.106
0.620
0.000
0.450
2.314
0.7466
2.696
0.536
Methylp
ropano
ate
0.128
0.600
0.000
0.450
2.431
0.7470
2.799
0.649
Methylb
utanoate
0.106
0.600
0.000
0.450
2.943
0.8880
3.037
0.957
Butanal
0.187
0.650
0.000
0.450
2.270
0.6880
2.818
0.488
Aceton
itrile
0.237
0.900
0.070
0.320
1.739
0.4042
3.193
0.343
Pyrid
ine
0.631
0.840
0.000
0.520
3.022
0.6750
3.755
0.315
1-Nitrop
ropane
0.242
0.950
0.000
0.310
2.894
0.7055
3.931
1.481
Water
0.000
0.600
0.590
0.460
0.245
0.1673
3.479
−1.211
PHYSICS AND CHEMISTRY OF LIQUIDS 19
simultaneously to give the numerical values of ck,il, ek,il, sk,il, ak,il, bk,il and lk,il that best describe theobserved gas-to-IL partition coefficient data. The equation coefficients for the set of log Pequations are solved in similar fashion to yield the numerical values of cp,il, ep,il, sp,il, ap,il, bp,il,vp,il. The Abraham model IL-specific equation coefficients for all derived correlations wereobtained by regression analysis using the IBM SPSS Statistics Package, Version 22. The statisticalinformation for each derived correlation equation was also determined using the statistical soft-ware package. Ion-specific equation coefficients for the [AllMIm]+, [OE3Am]+, [B3EP]
+ and[BMMorp]+ cations were calculated simply by subtracting the known anion-specific values fromthe IL-specific equation coefficients (e.g. ccation = cIL – canion; ecation = eIL – eanion, etc.). Thecomputational procedure will be illustrated in the next section.
3. Results and discussion
The ([AllMIm]+[N(CN)2]–) and ([AllMIm]+[Tf2N]
–) data sets are the two largest of the five data sets andcontain partition coefficients for 65 and 64 organic solutes, respectively. An analysis of the experimentallog P and log K values in Tables 3 and 4 yielded the following four Abraham model IL-specificcorrelations:
The standard errors in each of the calculated equation coefficients are given in parenthesesimmediately after the respective coefficient. An examination of the associated statistical informa-tion reveals that the derived correlations provide a very good mathematical description of solutetransfer into ([AllMIm]+[N(CN)2]
–) and ([AllMIm]+[Tf2N]–) as evidenced by the small standard
deviations, SD = 0.079 to 0.112 log units, near-unity squared correlation coefficients, R2 = 0.990 to0.998, and large Fisher F-statistical values, F = 1160 to 5328, for Equations (7)–(10). Figures 1 and2 depict a graphical comparison of the experimental log P data vs. back-calculated values based onour derived Abraham model correlations for solutes dissolved in ([AllMIm]+[N(CN)2]
–) and([AllMIm]+[Tf2N]
–), respectively. Similar comparisons of the log K values are shown in Figures3 and 4. There are insufficient experimental data to permit a training set and test set assessment ofthe predictive ability of Equations (7)–(10) by randomly splitting the entire databases in half.
The four mathematical correlations that have been obtained thus far should enable one topredict log P and log K values for additional organic solutes dissolved in ([AllMIm]+[N(CN)2]
–)
20 B. JIANG ET AL.
and ([AllMIm]+[Tf2N]–), provided of course that the solute’s descriptor values fall within the in
range of numerical values used in deriving Equations (7)–(10) above. Greater predictive abilitycan be obtained through the ion-specific equation coefficient version of the Abraham model. The[AllMIm]+-specific equation coefficients can be determined using the derived correlations foreither IL solvent. From a purely mathematical standpoint it is easier to perform the calculationsusing the correlations for ([AllMIm]+[Tf2N]
–). In developing the ion-specific model, Sprungerand co-workers [38–40] needed a reference point for calculating the numerical values forindividual ions. In an IL solvent the ions come as a cation–anion pair, and to calculate the valuesfor the cation one must know the values for the anion, and vice versa. To get around this problem,the authors set all of the equation coefficients for the [Tf2N]
– anion equal to zero. Hence, the
Figure 1. Comparison of the experimental log P data and back-calculated values based on Equation (7) for solutes dissolved in([AllMIm]+[N(CN)2]
–).
Figure 2. Comparison of the experimental log P data and back-calculated values based on Equation (9) for solutes dissolved in([AllMIm]+[Tf2N]
–).
PHYSICS AND CHEMISTRY OF LIQUIDS 21
coefficients in Equations (9) and (10) are not only the IL-specific equation coefficients for theentire ([AllMIm]+[Tf2N]
–) IL solvent, but also the ion-specific equation coefficients for the[AllMIm]+ cation.
Alternatively, one can calculate the ion-specific equation coefficients for the [AllMIm]+ cationfrom Equations (7) and (8) as log P and log K equation coefficients for the [N(CN)2]]
– anion areknown: (cp,anion = –0.257; ep,anion = 0.164; sp,anion = 0.446; ap,anion = 2.217; bp,anion = –0.256 andvp,anion = –0.243) and (ck,anion = –0.372; ek,anion = 0.345; sk,anion = 0.476; ak,anion = 2.270; bk,anion =–0.198 and lk,anion = –0.055).[41] We have summarised in Table 8 the results of this computation.We have taken the average of the two sets of calculations as the [AllMIm]+-specific equation
Figure 3. Comparison of the experimental log K data and back-calculated values based on Equation (8) for solutes dissolved in([AllMIm]+[N(CN)2]
–).
Figure 4. Comparison of the experimental log K data and back-calculated values based on Equation (10) for solutes dissolvedin ([AllMIm]+[Tf2N]
–).
22 B. JIANG ET AL.
coefficients for the log P and log K correlations. The average [AllMIm]+-specific equationcoefficients have been summed with the respective [Tf2N]
–-specific and [N(CN)2]–-specific
equation coefficients to constructive predictive Abraham model correlations for both([AllMIm]+[N(CN)2]
–) and ([AllMIm]+[Tf2N]–). The log K correlations predicted the experimen-
tal values in Tables 3 and 4 to within standard errors (SE) of 0.179 log units and 0.177 log units,respectively. Standard errors corresponding to the log P predictions were SE = 0.183 log units andSE = 0.189 log units for ([AllMIm]+[N(CN)2]
–) and ([AllMIm]+[Tf2N]–), respectively. Standard
errors are slightly larger for the log P predictions because of the added uncertainties in the log Kw
values that were used to convert the experimentally determined gas-to-IL partition coefficients towater-to-IL partition coefficients. The computations are in accord with our earlier observations inthat the best predictions are obtained using the IL-specific Abraham model correlations, which forthese two ILs would be Equations (7)–(10).
We suspect that we can improve on the predictions by recalculating the equation coefficientsfor the [N(CN)2]
– anion. Recently published experimental data for solutes dissolved in 1-butyl-3-methylimidazolium dicyanamide [19] and 1-butyl-4-methylpyridiniun dicyanamide [58] wouldnearly double the number of data points for IL solvents containing the [N(CN)2]
– anion.Reanalysis would be a massive computation task, however, as it would require regression analysison our entire IL database. The last regression analysis of the entire IL database was done just over2 years ago,[41] and at the time there were 3731 experimental log P values and 3786 experimentallog K values. It is not computationally feasible to perform a complete reanalysis every time that anew cation or anion is added to the database. A complete reanalysis will change most (if not all) ofthe existing values that have been calculated for the 40 cations and 16 anions that were in thedatabase when the values were last updated. It will be difficult for readers to keep track of thelatest set of equation coefficients. We prefer to update values every few years whenever there hasbeen sufficient new experimental values added to the large database to warrant the computationaleffort.
The ([B3EP]+[E2PO4]
–) data set is the smallest of the five IL data sets, and it containsexperimental partition coefficients for only 49 solutes. Preliminary regression analysis of theexperimental data in Table 5 gave an Abraham model log K correlation:
which had a negative numerical value for the bk,il coefficient. A negative bk,il coefficient is notrealistic as this would indicate that the H-bond acidity of ([B3EP]
+[E2PO4]–) is less than that of
Table 8. Summary of determination of the ion-specific equation coefficients for the [AllMIm]+ cation.
IL Solvent/ion Property c e s a b v l
([AllMIm]+[Tf2N]–) log P 0.000 0.058 0.703 −1.301 −4.344 3.159
[AllMIm]+ log P 0.000 0.058 0.703 −1.301 −4.344 3.159([AllMIm]+[N(CN)2]
–) log P −0.202 0.360 0.780 0.789 −4.475 2.621[N(CN)2]– log P −0.257 0.164 0.446 2.217 −0.256 −0.243[AllMIm]+ log P 0.055 0.196 0.334 −1.428 −4.219 2.864Average for [AllMIm]+ log P 0.028 0.127 0.519 −1.365 −4.282 3.012([AllMIm]+[Tf2N]
–) log K −0.420 0.081 2.493 2.368 0.599 0.643[AllMIm]+ log K −0.420 0.081 2.493 2.368 0.599 0.643([AllMIm]+[N(CN)2]
–) log K −0.815 0.534 2.719 4.550 0.450 0.514[N(CN)2]– log K −0.372 0.345 0.476 2.270 −0.198 −0.055[AllMIm]+ log K −0.443 0.189 2.243 2.280 0.648 0.569Average for [AllMIm]+ log K −0.432 0.135 2.368 2.324 0.624 0.606
PHYSICS AND CHEMISTRY OF LIQUIDS 23
the gas phase. We removed the bk,il·B from Equation (11), and re-analysed all of the experimentaldata in Table 5. The final Abraham model correlations,
describe the partitioning behaviour of 49 organic solutes into ([B3EP]+[E2PO4]
–) to within astandard deviation of 0.128 log units. As an informational note, there was very little loss indescriptive ability by removing the bk,il·B term from the log K equation. The standard deviationwas SD = 0.089 log units with the term included in the correlation vs. SD = 0.102 log unitswithout the term. Ion-specific equation coefficients are available in the published literature [41]for the [E2PO4]
– anion: (cp,anion = 0.071; ep,anion = 0.073; sp,anion = 0.006; ap,anion = 5.089; bp,anion= –0.832 and vp,anion = 0.184) and (ck,anion = 0.093; ek,anion = 0.107; sk,anion = –0.068; ak,anion = 5.071;bk,anion = –0.774 and lk,anion = 0.061). Subtraction of the anion-specific equation coefficients fromthe respective coefficients in Equations (12) and (13) results in the following set of coefficients forthe [B3EP]
The experimental partition coefficient data in Tables 6 and 7 were analysed in a similar fashionto yield the following two sets of Abraham model IL-specific correlations:
As an informational note, the ap,il·A term made a negligible contribution to the overall log Pcorrelation. The calculated ap,il coefficient was very small (0.021) and the standard error in thecoefficient was approximately seven times larger than the coefficient itself. Equations (14)–(17)provide reasonably accurate mathematical descriptions of the observed log P and log K values forsolute transfer into both ([OE3Am]+[Tf2N]
–) and ([BMMorp]+[C(CN)3]–). There is insufficient
24 B. JIANG ET AL.
experimental data to perform training set and test set analyses by splitting the data sets in half.Based on our past experience in deriving and using Abraham model correlations for IL solvents,however, we fully expect that Equations (14)–(17) will allow one to predict log P and log K valuesfor additional organic solutes to within approximately 0.13 log units of the observed values.
As noted above, for IL solvents that contain the [Tf2N]– anion the calculated equation
coefficients pertain not only the entire IL solvent, but to the cation as well. The coefficients thatare given in Equations (14) and (15) are the ion-specific equation coefficients for the [OE3Am]+
cation. Determination of the ion-specific equation coefficients for [BMMorp]+ is slightly moreinvolved and requires knowledge of the equation coefficients for the [C(CN)3]
– anion, which areavailable in the published tabulations in the paper by Stephens and co-workers.[41] The equationcoefficients for the [C(CN)3]
– anion are: (cp,anion = –0.079; ep,anion = 0.056; sp,anion = 0.276; ap,anion= 1.223; bp,anion = –0.070 and vp,anion = –0.008) and (ck,anion = –0.098; ek,anion = 0.094; sk,anion= 0.290; ak,anion = 1.338; bk,anion = –0.145 and lk,anion = 0.005). Subtraction of the anion-specificequation coefficients from the respective coefficients in Equations (16) and (17) results in thefollowing set of coefficients for the [BMMorp]+ cation: (cp,cation = –0.239; ep,cation = 0.318; sp,cation= 0.675; ap,cation = –1.223; bp,cation = –4.414 and vp,cation = 3.130) and (ck,cation = –0.676; ek,cation= 0.277; sk,cation = 2.472; ak,cation = 2.369; bk,cation = 0.597 and lk,cation = 0.638). The calculatedcation-specific equation coefficients can be combined with the 19 anion-specific equation coeffi-cients that we have previously determined.[41,44,45] For each of the four cations that we havestudied in the present communication, we can build log K and log P Abraham model predictivecorrelations for an additional 19 different IL solvents. This increases the Abraham model’spredictive capability by an additional 76 different IL solvents.
4. Conclusion
The Abraham model has been shown to provide very good mathematical descriptions of thewater-to-anhydrous IL and gas-to-anhydrous IL partition coefficients for solutes dissolved in([AllMIm]+[N(CN)2]
–), ([AllMIm]+[Tf2N]–), ([B3EP]
+[E2PO4]–), ([OE3Am]+[Tf2N]
–) and([BMMorp]+[C(CN)3]
–). The derived correlations back-calculate the observed partition coefficientdata to within standard deviations from SD = 0.073 log units to SD = 0.128 log units. As part ofthe present communication, cation-specific equation coefficients have been calculated for[AllMIm]+, [OE3Am]+, [B3EP]
+ and [BMMorp]+. For each of the four cations that we havestudied in the present communication, we can build log K and log P Abraham model predictivecorrelations for an additional 19 different IL solvents. This increases the Abraham model’spredictive capability by an additional 76 different IL solvents.
Acknowledgements
Bihan Jiang and Melissa Horton thank the University of North Texas’s Texas Academy of Math and Science(TAMS) program for a summer research award.
Disclosure statement
No potential conflict of interest was reported by the authors.
References
[1] Asuman C, Yu G, Guan Y, et al. Extractive denitrogenation of fuel oils with dicyanamide-based ionic liquids.Green Chem. 2011;13:3300–3305. doi:10.1039/c1gc15747g.
[2] Asumana C, Haque R, Yu L, et al. Desulfurization of real fuel oils by extraction with ionic liquids. SepSciTechnol. 2013;48:2582–2588. doi:10.1080/01496395.2013.804559.
[3] Gao H, Li Y, Wu Y, et al. Extractive desulfurization of fuel using 3-methylpyridinium-based ionic liquids.Energy Fuels. 2009;23:2690–2694. doi:10.1021/ef900009g.
[4] Farzin Najad N, Shams Soolan E, Adibi M, et al. Imidazolium-based alkylsulfate ionic liquids and removal ofsulfur content from model of gasoline. Petrol Sci Technol. 2013;31:472–480. doi:10.1080/10916466.2010.481651.
[5] Anantharaj R, Banerjee T. COSMO-RS-based screening of ionic liquids as green solvents in denitrificationstudies. Ind Eng Chem Res. 2010;49:8705–8725. doi:10.1021/ie901341k.
[6] Banerjee T, Anantharaj R. COSMO-RS based predictions for the desulphurization of diesel oil using ionicliquids: effect of cation and anion combination. Fuel Process Technol. 2010;92:39–52.
[7] Oliveira LMC, Ribeiro FRG, Alcantara ML, et al. High pressure vapor-liquid equilibria for binary methaneand protic ionic liquid based on propionate anions. Fluid Phase Equilibr. Forthcoming 2016. doi:10.1016/j.fluid.2016.03.021.
[8] Singh ZV, Cowan MG, McDanel WM, et al. Determination and optimization of factors affecting CO2/CH4
[9] Liu X, He M, Lv N, et al. Selective absorption of CO2 from H2, O2 and N2 by 1-hexyl-3-methylimidazoliumtris(pentafluoroethyl)trifluorophosphate. J Chem Thermodyn. 2016;97:48–54. doi:10.1016/j.jct.2016.01.013.
[10] Mohshim DF, Mukhtar H, Man Z. Comparison study of emim [Tf2N] and emim [CF3SO3] effects onpolyethersulfone membrane for CO2/CH4 separation. J Appl Sci. 2014;14:1083–1087. doi:10.3923/jas.2014.1083.1087.
[11] Cowan MG, Gin DL, Noble RD. Poly(ionic liquid)/ionic liquid ion-gels with high ‘free’ ionic liquid content:platform membrane materials for CO2/light gas separations. Acc Chem Res. 2016;49:724–732. doi:10.1021/acs.accounts.5b00547.
[12] Wang G, Hou W, Xiao F, et al. Low-viscosity triethylbutylammonium acetate as a task-specific ionic liquid forreversible CO2 absorption. J Chem Eng Data. 2011;56:1125–1133. doi:10.1021/je101014q.
[13] Huang K, Wang G-N, Dai Y, et al. Dicarboxylic acid salts as task-specific ionic liquids for reversibleabsorption of SO2 with a low enthalpy change. RSC Adv. 2013;3:16264–16269. doi:10.1039/c3ra42256a.
[14] Gimeno MP, Mayoral MC, Andres JM. Influence of temperature on CO2 adsorption rate and capacity in ionicliquids. Energy Fuels. 2013;27:3928–3935. doi:10.1021/ef401063r.
[15] Karousos DS, Kouvelos E, Sapalidis A, et al. Novel inverse supported ionic liquid absorbents for acidic gasremoval from flue gas. Ind Eng Chem Res. 2016;55:5748–5762. doi:10.1021/acs.iecr.6b00664.
[16] Bates ED, Mayton R, Ntai I, et al. CO2 capture by a task-specific ionic liquid. J Am Chem Soc. 2002;124:926–927. doi:10.1021/ja017593d.
[17] Li X, Zhang L, Zheng Y, et al. Effect of SO2 on CO2 absorption in flue gas by ionic liquid 1-ethyl-3-methylimidazolium acetate. Ind Eng Chem Res. 2015;54:8569–8578. doi:10.1021/acs.iecr.5b02208.
[18] Chen K, Lin W, Yu X, et al. Designing of anion-functionalized ionic liquids for efficient capture of SO2 fromflue gas. AIChE J. 2015;61:2028–2034. doi:10.1002/aic.14793.
[19] Domanska U, Wlazlo M, Karpinska M. Activity coefficients at infinite dilution of organic solvents and waterin 1-butyl-3-methylimidazolium dicyanamide. A literature review of hexane/hex-1-ene separation. FluidPhase Equilibr. 2016;417:50–61. doi:10.1016/j.fluid.2016.02.004.
[20] Wlazlo M, Karpinska M, Domanska U. A 1-alkylcyanopyridinium-based ionic liquid in the separationprocesses. J Chem Thermodyn. 2016;97:253–260. doi:10.1016/j.jct.2016.01.017.
[21] Ayad A, Mutelet F, Negadi A, et al. Activity coefficients at infinite dilution for organic solutes dissolved in two1-alkylquinuclidinium bis(trifluoromethylsulfonyl)imides bearing alkyl side chains of six and eight carbons. JMol Liq. 2016;215:176–184. doi:10.1016/j.molliq.2015.12.029.
[22] Ayad A, Mutelet F, Abumandour E-S, et al. Activity coefficients at infinite dilution of organic solutes inmethylphosphonate based ionic liquids using gas-liquid chromatography. J Chem Thermodyn. 2015;86:116–122. doi:10.1016/j.jct.2015.02.023.
[23] Wytze Meindersma G, Galan Sanchez LM, Hansmeier AR, et al. Application of task-specific ionic liquids forintensified separations. Monatsh Chem. 2007;138:1125–1136. doi:10.1007/s00706-007-0757-4.
[24] Revelli A-L, Mutelet F, Jaubert J-N. Prediction of partition coefficients of organic compounds in ionic liquids:use of a linear solvation energy relationship with parameters calculated through a group contribution method.Ind Eng Chem Res. 2010;49:3883–3892. doi:10.1021/ie901776z.
[25] Grubbs LM, Ye S, Saifullah M, et al. Correlations for describing gas-to-ionic liquid partitioning at 323 K basedon ion-specific equation coefficient and group contribution versions of the Abraham model. Fluid PhaseEquilibr. 2011;301:257–266. doi:10.1016/j.fluid.2010.12.005.
[26] Mutelet F, Ortega-Villa V, Moise J-C, et al. Prediction of partition coefficients of organic compounds in ionicliquids using a temperature-dependent linear solvation energy relationship with parameters calculatedthrough a group contribution method. J Chem Eng Data. 2011;56:3598–3606. doi:10.1021/je200454d.
[27] Grubbs LM, Acree WE Jr, Abraham MH. Correlation of enthalpies of solvation of organic vapors and gases inionic liquid solvents using a group contribution version of the Abraham solvation parameter model.Thermochim Acta. 2010;511:96–101. doi:10.1016/j.tca.2010.07.030.
[28] Lazzus JA, Pulgar-Villarroel G. A group contribution method to estimate the viscosity of ionic liquids atdifferent temperatures. J Mol Liq. 2015;209:161–168. doi:10.1016/j.molliq.2015.05.030.
[29] Gharagheizi F, Ilani-Kashkouli P, Mohammadi AH, et al. Development of a group contribution method fordetermination of viscosity of ionic liquids at atmospheric pressure. Chem Eng Sci. 2012;80:326–333.doi:10.1016/j.ces.2012.06.045.
[30] Lazzus JA. A group contribution method to predict the thermal conductivity λ(T,P) of ionic liquids. FluidPhase Equilibr. 2015;405:141–149. doi:10.1016/j.fluid.2015.07.015.
[31] Wu K-J, Zhao C-X, He C-H. Development of a group contribution method for determination of thermalconductivity of ionic liquids. Fluid Phase Equilibr. 2013;339:10–14. doi:10.1016/j.fluid.2012.11.024.
[32] Nancarrow P, Lewis M, Abou Chacra L. Group contribution methods for estimation of ionic liquid heatcapacities: critical evaluation and extension. Chem Eng Technol. 2015;38:632–644. doi:10.1002/ceat.v38.4.
[33] Albert J, Mueller K. A group contribution method for the thermal properties of ionic liquids. Ind Eng ChemRes. 2014;53:17522–17526. doi:10.1021/ie503366p.
[34] Mueller K, Albert J. Contribution of the individual ions to the heat capacity of ionic liquids. Ind Eng ChemRes. 2014;53:10343–10346. doi:10.1021/ie501575n.
[35] Gharagheizi F, Ilani-Kashkouli P, Mohammadi AH. Group contribution model for estimation of surfacetension of ionic liquids. Chem Eng Sci. 2012;78:204–208. doi:10.1016/j.ces.2012.05.008.
[36] Paduszynski K, Domanska U. A new group contribution method for prediction of density of pure ionicliquids over a wide range of temperature and pressure. Ind Eng Chem Res. 2012;51:591–604. doi:10.1021/ie202134z.
[37] Abraham MH. Scales of solute hydrogen-bonding: their construction and application to physicochemical andbiochemical processes. Chem Soc Rev. 1993;22:73–83. doi:10.1039/cs9932200073.
[38] Sprunger L, Clark M, Acree WE Jr, et al. Characterization of room temperature ionic liquids by the Abrahammodel with cation-specific and anion-specific equation coefficients. J Chem Inf Model. 2007;47:1123–1129.doi:10.1021/ci7000428.
[39] Sprunger LM, Proctor A, Acree WE Jr, et al. LFER Correlations for room temperature ionic liquids:separation of equation coefficients into individual cation-specific and anion-specific contributions. FluidPhase Equilibr. 2008;265:104–111. doi:10.1016/j.fluid.2008.01.006.
[40] Sprunger LM, Gibbs J, Proctor A, et al. Linear free energy relationship correlations for room temperatureionic liquids: revised cation-specific and anion-specific equation coefficients for predictive applicationscovering a much larger area of chemical space. Ind Eng Chem Res. 2009;48:4145–4154. doi:10.1021/ie801898j.
[41] Stephens TW, Chou V, Quay AN, et al. Thermochemical investigations of solute transfer into ionic liquidsolvents: updated Abraham model equation coefficients for solute activity coefficient and partition coefficientpredictions. Phys Chem Liq. 2014;52:488–518. doi:10.1080/00319104.2014.880114.
[42] Lu A, Jiang B, Cheeran S, et al. Abraham model ion-specific equation coefficients for the 1-butyl-2,3-dimethyimidazolium and 4-cyano-1-butylpyridinium cations calculated from measured gas-to-liquid partitioncoefficient data. Phys Chem Liq. 2016;1–20. Ahead of Print. doi:10.1080/00319104.2016.1191634.
[43] Twu P, Anderson JL, Stovall DM, et al. Determination of the solubilising character of 2-methoxyethyl(dimethyl)-ethylammonium tris(pentafluoroethyl)trifluorophosphate based on the Abraham solvation para-meter model. Phys Chem Liq. 2016;54:110–126. doi:10.1080/00319104.2015.1068665.
[44] Mutelet F, Alonso D, Stephens TW, et al. Infinite dilution activity coefficients of solutes dissolved in twotrihexyl(tetradecyl)phosphonium ionic liquids. J Chem Eng Data. 2014;59:1877–1885. doi:10.1021/je500050p.
[45] Stephens TW, Hart E, Kuprasertkul N, et al. Abraham model correlations for describing solute transfer intoionic liquid solvents: calculation of ion-specific equation coefficients for the 4,5-dicyano-2-(trifluoromethyl)imidazolide anion. Phys Chem Liq. 2014;52:777–791. doi:10.1080/00319104.2014.929949.
[46] Wlazlo M, Gawkowska J, Domanska U. Separation based on limiting activity coefficients of various solutes in1-allyl-3-methylimidazolium dicyanamide ionic liquid. Ind Eng Chem Res. 2016;55:5054–5062. doi:10.1021/acs.iecr.6b00942.
[47] Wlazlo M, Karpinska M, Domanska U. Thermodynamics and selectivity of separation based on activitycoefficients at infinite dilution of various solutes in 1-allyl-3-methylimidazolium bis[(trifluoromethyl)sulfo-nyl]imide ionic liquid. J Chem Thermodyn. Forthcoming 2016.
[48] Wlazlo M, Domanska U. Gamma infinity data for the separation of water-butan-1-ol mixtures using ionicliquids. Sep Purification Technol. 2016;162:162–170. doi:10.1016/j.seppur.2016.02.015.
[49] Krolikowska M, Orawiec M. Activity coefficients at infinite dilution of organic solutes and water intributylethylphosphonium diethylphosphate using gas-liquid chromatography: thermodynamic properties ofmixtures containing ionic liquids. J Chem Eng Data. 2016;61:1793–1802. doi:10.1021/acs.jced.5b00980.
[50] Domanska U, Lukoshko EV. Thermodynamics and activity coefficients at infinite dilution for organic solutesand water in the ionic liquid 1-butyl-1-methylmorpholinium tricyanomethanide. J Chem Thermodyn.2014;68:53–59. doi:10.1016/j.jct.2013.08.030.
[51] Abraham MH, Acree WE Jr, Brumfield M, et al. Deduction of physicochemical properties from solubilities: 2,4-dihydroxybenzophenone, biotin, and caprolactam as examples. J Chem Eng Data. 2015;60:1440–1446.doi:10.1021/je501140p.
[52] Schmidt A, Grover D, Zettl H, et al. Determination of Abraham model solute descriptors for isophthalic acidfrom experimental solubility data in organic solvents at 298 K. Phys Chem Liq. 2016;1–11. Ahead of Print.doi:10.1080/00319104.2016.1149178.
[53] Brumfield M, Wadawadigi A, Kuprasertkul N, et al. Determination of Abraham model solute descriptors forthree dichloronitrobenzenes from measured solubilities in organic solvents. Phys Chem Liq. 2015;53:163–173.doi:10.1080/00319104.2014.972555.
[54] Holley K, Acree WE Jr, Abraham MH. Determination of Abraham model solute descriptors for 2-ethylan-thraquinone based on measured solubility ratios. Phys Chem Liq. 2011;49:355–365. doi:10.1080/00319101003646553.
[55] Abraham MH, Ibrahim A, Zissimos AM. Determination of sets of solute descriptors from chromatographicmeasurements. J Chromatogr A. 2004;1037:29–47. doi:10.1016/j.chroma.2003.12.004.
[56] Zissimos AM, Abraham MH, Du CM, et al. Calculation of Abraham descriptors from experimental data fromseven HPLC systems; evaluation of five different methods of calculation. J Chem Soc Perkin Trans 2.2002;2001–2010. doi:10.1039/b206927j.
[57] Zissimos AM, Abraham MH, Barker MC, et al. Calculation of Abraham Descriptors from solvent-waterpartition coefficients in four different systems; evaluation of different methods of calculation. J Chem SocPerkin Trans 2. 2002;470–477. doi:10.1039/b110143a.
[58] Krolikowski M, Krolikowska M. The study of activity coefficients at infinite dilution for organic solutes andwater in 1-butyl-4-methylpyridinium dicyanamide, [B4MPy][DCA] using GLC. J Chem Thermodyn.2014;68:138–144. doi:10.1016/j.jct.2013.09.007.