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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
2-Butanol with Toulene and Water
Components:
(1) Water; H2O; [7732-18-5]
NIST Chemistry WebBook
for detail
(2) 2-Butanol (sec-butanol, sec-butyl alcohol, (RS)-2-butanol, dl-2-butanol, DL-2-butanol); C4H10O; [78-92-2]
NIST Chemistry WebBook
for detail
(3) Toluene (methylbenzene); C7H8; [108-88-3]
NIST Chemistry WebBook
for detail
Evaluator:
A. Skrzecz, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland (1996.06)
Critical Evaluation:
A survey of reported compositions along the saturation curve (sat), and compositions of coexisting phases in equilibrium (eq.) for the system 2-butanol-toluene-water is given in Table 81.
Saturation curve
The system 2-butanol-toluene-water forms a miscibility gap of type 2. Two binary systems, 2-butanol-water and toluene-water are partially miscible. The data of these systems were compiled and critically evaluated in previously published SDS volumes, Refs. 3 and 4, respectively. The recommended values of mutual solubility of toluene-watter system at 298.2 K are
x
'
2
=0.9972 and
x
"
2
=0.000 104 (Ref. 3). The mutual solubility of 2-butanol-water system at 298.2 K calculated on the basis of Ref. 4 are
x
'
1
=0.322 and
x
"
1
=0.0510. Letcher and Siswana
2
report at 298.2 K mutual solubility of the binary systems toluene-water and 2-butanol-water as
x
'
2
=0.999,
x
"
2
=0.000 and
x
'
1
=0.312,
x
"
1
=0.051, respectively. These binary data are consistent with recommended data since they are within the accuracy estimated by the authors (0.01 mole fraction). The experimental data on saturation curve were reported in Refs. 1 and 2 at the same temperature and are consistent with one another. Data presented by Evans and Lin
1
show the miscibility gap slightly to be smaller (of about 0.02-0.03 mole fraction of water) than found by Letcher and Siswana,
2
especially in the region of 0.26<
x
2
<0.75. The maximum 2-butanol concentration observed on the organic-rich branch of the saturation curve at 298 K in
x
1
=0.489±0.005. The data for the organic-rich phase of the saturation curve,
1,2
(points reported as phases in equilibrium were included) were used to construct the equation:
x
1
=0.618 84+0.053 26 ln(
x
2
)–0.183 05
x
2
–0.452 04
x
2
2
.
The model applies to the region 0.004<
x
2
<0.94. The parameters were calculated by the least-squares method and the standard error of estimate was 0.0083. There was an error (presumably a typographic) in Ref. 2 at the point
x
1
=0.120
x
2
=0.885 on saturation curve (the sum of compositions was greater than 1.0) and the experimental point was rejected. Selected points on the saturation curve, calculated the above equation together with the “best” values of Refs. 3 and 4 are presented in Table 82 and as solid line in
Figure 44
. The water-rich branch of saturation curve contains small amount of toluene (
x
2
<0.0001) and toluene concentration was not reported in either paper. These experimental points were not described by any model.
Phases in equilibrium
Compositions of coexisting phases in equilibrium for ther ternary system 2-butanol-toluene-water were reported in both references at 298.2 K and cover the whole range of the miscibility gap. The compositions of phases in equilibrium reported in Refs. 1 and 2 are consistent with one another. Both data sets are considered tentative. All experimental tie lines are presented in
Figure 44
together with experimental points forming the solubility curve.
Experimental Data:
(Notes on the Nomenclature)
TABLE 81. Summary of experimental data for the system 2-butanol-toluene-water
Author
T/K
DataType
Reference
Evans and Lin, 1968
298
sol. (21), eq. (5)
1
Letcher and Siswana, 1992
298
sol. (15), eq. (4)
2
TABLE 82. Calculated compositions along the saturation curve 298.2 K. (organic-rich phase)
T/K
Mole Fraction x
1
Mole Fraction x
2
298.2
0.312
0.0000 Ref. 4
298.2
0.3717
0.0100
298.2
0.4066
0.0200
298.2
0.4394
0.0400
298.2
0.4564
0.0600
298.2
0.4668
0.0800
298.2
0.4734
0.1000
298.2
0.4774
0.1200
298.2
0.4796
0.1400
298.2
0.4804
0.1600
298.2
0.4799
0.1800
298.2
0.4784
0.2000
298.2
0.4761
0.2200
298.2
0.4729
0.2400
298.2
0.4689
0.2600
298.2
0.4644
0.2800
298.2
0.4591
0.3000
298.2
0.4533
0.3200
298.2
0.4469
0.3400
298.2
0.4399
0.3600
298.2
0.4325
0.3800
298.2
0.4245
0.4000
298.2
0.4160
0.4200
298.2
0.4071
0.4400
298.2
0.3976
0.4600
298.2
0.3877
0.4800
298.2
0.3774
0.5000
298.2
0.3666
0.5200
298.2
0.3554
0.5400
298.2
0.3437
0.5600
298.2
0.3316
0.5800
298.2
0.3191
0.6000
298.2
0.3061
0.6200
298.2
0.2928
0.6400
298.2
0.2790
0.6600
298.2
0.2648
0.6800
298.2
0.2502
0.7000
298.2
0.2198
0.7200
298.2
0.2198
0.7400
298.2
0.2040
0.7600
298.2
0.1878
0.7800
298.2
0.1712
0.8000
298.2
0.1542
0.8200
298.2
0.1368
0.8400
298.2
0.1191
0.8600
298.2
0.1009
0.8800
298.2
0.0823
0.9000
298.2
0.0634
0.9200
298.2
0.0441
0.9400
298.2
0.0000
0.9972 Ref. 3
298.2
0.0000
0.000 104 Ref. 3
298.2
0.1510
0.0000 Ref. 4
View Figure 1 for this Evaluation
Notes:
Table 81
Number of experimental points in parentheses.
References: (Click a link to see its experimental data associated with the reference)
1
Evans, L.R.; Lin, J.S., J. Chem. Eng. Data 13, 14 (1968).
2
Letcher, T.M.; Siswana, P.M., Fluid Phase Equilib. 74, 203 (1992).
3 Shaw, D.G., ed., Solubility Data Series, Vol. 37, Hydrocarbons with Water and Seawater, Part I: Hydrocarbons C5 to C7 (Pergamon, New York, 1989).
4 Barton, A.F. M., ed., Solubility Data Series, Vol. 15, Alcohols with Water (Pergamon, New York 1984).