Infinite dilution activity coefficient measurements of organic solutes in fluorinated ionic liquids by gas-liquid chromatography and the inert gas stripping method

5.1.8. 1-methyl-3-octylimidazolium hexafluorophosphate, [MOIM][PF6]

Table 5-26: Activity coefficients at infinite dilution of organic solutes in 1-methyl-3-

octylimidazolium hexafluorophosphate with n3 = 6.69 mmol (28.55 %)
at T = (313.15, 323.15 and 333.15) K.

Experimental at /K

Solute	n3/mmol	T=313.15	T=323.15		T=333.15	n-pentane
6.69	8.21	8.06	7.83		n-hexane
6.69	10.75	10.56	10.20		n-heptane
6.69	14.07	13.78	13.24		n-octane
6.69	18.34	17.87	17.04		n-decane
6.69	31.75	30.25	28.23		n-undecane
6.69	42.06	39.62	36.52		Hex-1-ene
6.69	6.17	6.15	6.06		Hept-1-ene
6.69	8.23	8.18	8.02		Oct-1-ene
6.69	10.77	10.66	10.39		Non-1-ene
6.69	14.16	13.93	13.50		Dec-1-ene
6.69	16.32	16.52	16.34		Undec-1-ene
6.69	25.10	24.01	22.75		Pent-1-yne
6.69	1.70	1.75	1.78		Hex-1-yne
6.69	2.24	2.30	2.34		Hept-1-yne
6.69	2.81	2.87	2.93		Oct-1-yne
6.69	3.77	3.87	3.94		Non-1-yne
6.69	4.38	4.65	4.83		Cyclopentane
6.69	5.02	4.92	4.77		Cyclohexane
6.69	6.74	6.56	6.29		Cycloheptane
6.69	8.24	7.97	7.63		Cyclooctane
6.69	10.21	9.85	9.39		Methanol
6.69	1.77	1.61	1.46		Ethanol
6.69	2.22	2.00	1.79		Benzene
6.69	0.96	0.99	1.00		Toluene
6.69	1.31	1.35	1.37		Ethylbenzene
6.69	1.95	1.98	1.99

Table 5-27: Activity coefficients at infinite dilution of organic solutes in 1-methyl-3-

octylimidazolium hexafluorophosphate with n3 = 5.135 mmol (33.26 %)
at T = (313.15, 323.15 and 333.15) K.

Experimental at /K

Solute	n3/mmol	T=313.15	T=323.15		T=333.15	n-pentane
5.14	8.32	8.11	7.99		n-hexane
5.14	11.01	10.68	10.41		n-heptane
5.14	14.30	13.59	13.21		n-octane
5.14	17.64	17.09	16.93		n-decane
5.14	31.68	30.80	28.98		n-undecane
5.14	41.33	40.13	36.99		Hex-1-ene
5.14	6.45	6.29	6.15		Hept-1-ene
5.14	8.19	8.12	8.14		Oct-1-ene
5.14	10.30	10.23	10.34		Non-1-ene
5.14	13.48	13.25	13.28		Dec-1-ene
5.14	16.66	16.30	16.36		Undec-1-ene
5.14	25.24	24.79	22.52		Pent-1-yne
5.14	1.72	1.79	1.84		Hex-1-yne
5.14	2.33	2.38	2.43		Hept-1-yne
5.14	2.93	2.98	3.04		Oct-1-yne
5.14	3.90	3.94	4.03		Non-1-yne
5.14	4.47	4.71	4.91		Cyclopentane
5.14	5.06	4.95	4.79		Cyclohexane
5.14	6.82	6.61	6.30		Cycloheptane
5.14	8.02	7.74	7.75		Cyclooctane
5.14	9.92	9.51	9.37		Methanol
5.14	1.85	1.65	1.50		Ethanol
5.14	2.32	2.05	1.82		Benzene
5.14	0.97	0.99	1.03		Toluene
5.14	1.36	1.37	1.41		Ethylbenzene
5.14	1.95	1.98	2.02

Table 5-28: Average activity coefficients at infinite dilution of organic solutes in 1-

methyl-3-octylimidazolium hexafluorophosphate at T = (313.15, 323.15 and 333.15) K.

Experimental		at /K			Solute
T=313.15	T=323.15	T=333.15		n-pentane
8.27	8.09	7.91		n-hexane
10.88	10.62	10.31		n-heptane
14.19	13.69	13.23		n-octane
17.99	17.48	16.99		n-decane
31.72	30.53	28.61		n-undecane
41.70	39.88	36.76		Hex-1-ene
6.31	6.22	6.11		Hept-1-ene
8.21	8.15	8.08		Oct-1-ene
10.54	10.45	10.37		Non-1-ene
13.82	13.59	13.39		Dec-1-ene
16.49	16.41	16.35		Undec-1-ene
25.17	24.40	22.64		Pent-1-yne
1.71	1.77	1.81		Hex-1-yne
2.29	2.34	2.39		Hept-1-yne
2.87	2.93	2.99		Oct-1-yne
3.84	3.91	3.99		Non-1-yne
4.43	4.68	4.87		Cyclopentane
5.04	4.94	4.78		Cyclohexane
6.78	6.59	6.30		Cycloheptane
8.13	7.86	7.69		Cyclooctane
10.07	9.68	9.38		Methanol
1.81	1.63	1.48		Ethanol
2.27	2.03	1.81		Benzene
0.97	0.99	1.02		Toluene
1.34	1.36	1.39		Ethylbenzene
1.95	1.98	2.01

Table 5-29: Excess molar enthalpies at infinite dilution of organic solutes for the ionic

liquid 1-methyl-3-octylimidazolium hexafluorophosphate, calculated using the Gibbs-
Helmholtz equation.

SOLUTE	Linear regression using Eq.(2-11)
	n-pentane
0.229		1.381	0.999	1.90			n-hexane
0.283		1.485	0.994	2.35			n-heptane
0.366		1.485	1.000	3.04			n-octane
0.300		1.933	0.999	2.49			n-decane
0.537		1.748	0.973	4.46			n-undecane
0.656		1.643	0.966	5.45			Hex-1-ene
0.172		1.294	0.991	1.43			Hept-1-ene
0.083		1.840	0.996	0.69			Oct-1-ene
0.085		2.084	0.999	0.71			Non-1-ene
0.165		2.099	0.999	1.37			Dec-1-ene
0.045		2.660	0.996	0.37			Undec-1-ene
0.551		1.473	0.937	4.58			Pent-1-yne
-0.297		1.487	0.989	-2.47			Hex-1-yne
-0.224		1.541	0.998	-1.86			Hept-1-yne
-0.205		1.708	0.999	-1.70			Oct-1-yne
-0.200		1.982	0.997	-1.66			Non-1-yne
-0.501		3.088	0.994	-4.16			Cyclopentane
0.276		0.739	0.982	2.29			Cyclohexane
0.386		0.684	0.980	3.21			Cycloheptane
0.291		1.165	0.986	2.42			Cyclooctane
0.368		1.133	0.998	3.06			Methanol
1.050		-2.760	1.000	8.73			Ethanol
1.195		-2.996	0.999	9.94			Benzene
-0.263		0.806	0.999	-2.19			Toluene
-0.210		0.960	0.996	-1.75			Ethylbenzene
-0.145		1.132	0.999	-1.21

2.95 3 3.05 3.1 3.15 3.2 3.25

1000K/T

4

3.5

¹¹¹( EP13)

3

2.5

2

1.5

Figure 5-48: Plots of versus for n-alkanes in [MOIM] [PF6] together with a linear

correlation of the data using the Gibbs-Helmholtz equation; () n-pentane, () n-hexane,
(?) n-heptane, (?) n-octane, () n-decane and (?) n-undecane.

	3.5
3
2
1.5

2.95 3 3.05 3.1 3.15 3.2 3.25

1000/T/K^-1

Figure 5-49: Plots of versus for alk-1-enes in [MOIM] [PF6] together with a linear

correlation of the data using the Gibbs-Helmholtz equation; () hex-1-ene, () hept-1-ene,
(?) oct-1-ene, (?) non-1-ene, () dec-1-ene and (?) undec-1-ene.

2.95 3 3.05 3.1 3.15 3.2 3.25

1000K/T

In(L13)

0.8

0.6

0.4

1.8

1.6

1.4

1.2

1

Figure 5-50: Plots of versus for alk-1-ynes in [MOIM] [PF6] together with a linear

correlation of the data using the Gibbs-Helmholtz equation; () pent-1-yne, () hex-1-yne,
(?) hept-1-yne, (?) oct-1-yne and () non-1-yne.

2.95 3 3.05 3.1 3.15 3.2 3.25

1000K/T

2.5

2

ln( L13)

1.5

1

Figure 5-51: Plots of versus for cycloalkanes in [MOIM] [PF6] together with a linear

correlation of the data using the Gibbs-Helmholtz equation; () cyclopentane, () cyclohexane,
(?) cycloheptane and (?) cyclooctane.

2.95 3 3.05 3.1 3.15 3.2 3.25

1000K/T

In( EF13)

0.8

0.6

0.4

0.2

1

Figure 5-52: Plots of versus for alkanols in [MOIM] [PF6] together with a linear

correlation of the data using the Gibbs-Helmholtz equation; () methanol and () ethanol.

^-0.22.95 3 3.05 3.1 3.15 3.2 3.25

1000K/T

In( E1:13)

0.8

0.6

0.4

0.2

0

Figure 5-53: Plots of versus for alkylbenzenes in [MOIM] [PF6] together with a linear

correlation of the data using the Gibbs-Helmholtz equation; () benzene, () toluene and
(?) ethylbenzene.

0 1 2 3 4 5 6 7 8 9 10 11 12 13

4

3

In( EF13)

2

1

0

-1

Nc

Figure 5-54: Plots of versus the number of carbon atoms at 313.15 K for () n-alkanes,

() alk-1-enes, (?) alk-1-ynes, and (?) cycloalkanes, (+) alkanols and (?) alkylbenzenes in
[MOIM] [PF6]

5.2. Results from the inert gas stripping technique

5.2.1. N-methyl-2-pyrrolidone, NMP

Table 5-30: Experimental infinite dilution activity coefficients of n-hexane as well as cyclohexane in NMP obtained by the dilutor method and comparison with literature data taken from Gruber et al. (1999). Experimental values were determined using equation (3-90).

T K	Experimental data		Literature data				Deviation# %
		D/ cm^3.min^-1
303.15
7.550	13.278	21.4 -35.4	13.10			1.359	303.15
14.96	13.28	21.4 -35.4	13.10			1.374	303.15
20.23	13.271	21.4 -35.4	13.10			1.305	313.15
7.480	11.561	21.4 -35.4	11.80			-2.025	313.15
15.21	11.568	21.4 -35.4	11.80			-1.966	313.15
19.94	11.549	21.4 -35.4	11.80			-2.127	323.15
7.620	10.992	21.4 -35.4	10.90			0.844	323.15
15.09	11.009	21.4 -35.4	10.90			1.000	323.15
19.85	10.983	21.4 -35.4	10.90			0.761	Cyclohexane
303.15
7.510	8.199	21.4 -35.4	8.06			1.725	303.15
15.07	8.213	21.4 -35.4	8.06			1.898	303.15
21.53	8.184	21.4 -35.4	8.06			1.538	313.15
7.660	7.546	21.4 -35.4	7.40			1.973	313.15
15.14	7.539	21.4 -35.4	7.40			1.878	313.15
20.39	7.541	21.4 -35.4	7.40			1.905	323.15
7.480	6.836	21.4 -35.4	6.80			0.529	323.15
14.98	6.841	21.4 -35.4	6.80			0.603	323.15
21.43	6.839	21.4 -35.4	6.80			0.574

# Relative deviation, R.D., given by