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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
2-Butanol with Cyclohexene 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) Cyclohexane; C6H12; [110-82-7]
NIST Chemistry WebBook
for detail
Evaluator:
A. Skrzecz, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland (1995.09)
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-cyclohexane-water is given in Table 79.
Saturation curve
The ternary system 2-butanol-cyclohexane-water forms a miscibility gap of type 2. Two binary systems, cyclohexane-water and 2-butanol-water, form miscibility gaps. The data for these binary systems were compiled and critically evaluated in previously published SDS volumes, Refs. 3 and 4, respectively. The recommended values of mutual solubility at 298 K are: for cyclohexane-water system
x
"
2
=1.2·10
–5
and
x
'
3
=3.7·10
–4
, Ref. 3, and for 2 butanol-water systems
x
'
1
=0.322 and
x
"
1
=0.051, Ref. 4. Letcher
et al
.
2
reported ternary data and mutual solubility for binary systems. The end points of saturation curve were reported to be
x
'
2
=0.999 and pure water. This is inconsistent with the recommended values but within the accuracy of experimental measurements (0.001 mole fraction) stated by the authors. Binary solubility data of the 2-butanol-water system reported in Ref. 2 as
x
'
1
=0.312 and
x
"
1
=0.051 are consistent with the “best values” reported in the critical evaluation, Ref. 3. Plackov and Stern
1
reported only solubility of 2-butanol in water,
x
"
1
=0.0544. This result is also consistent with recommended data. These experimental data are consistent with one another.
Compositions of the water-rich phase of the ternary system, Refs. 1 and 2, were reported as binary 2-butanol-water mixtures. The analytical methods could not detect cyclohexane. Therefore the water-rich branch could not be evaluated. Phase equilibrium data were used to construct the saturation curve for the organic-rich phase. Data for 298.2 K were described by the equation:
x
"
1
=0.683 11+0.066 20 ln(
x
2
)–0.341 40
x
2
=–0.349 78
x
2
2
.
The model describes the region 0.01<
x
2
<0.96. The parameters were calculated by the least-squares method. The standard error estimate was 0.0061. The points on the saturation curve calculated by this equation for selected concentrations of cyclohexane in the mixture are presented in Table 80 and in
Fig. 43
as a calculated binodal curve (solid line).
Phases in equilibrium
Compositions of coexisting phases in equilibrium for the ternary system 2-butanol-cyclohexane-water were reported in two references at 298.2 K using similar experimental procedures. First equilibrium was reached, then the phases were separated and the composition of each phase was determined. Compositions of water-rich phase in equilibrium were reported as binary 2-butanol-water mixtures; the analytical methods could not detect cyclohexane. The tie lines cover the whole area of the miscibility gap and are consistent within each data set. Distribution of 2-butanol differs between data sets with Letcher
et al
.
2
reporting lower concentrations of alcohol in the water-rich phase than Plackov and Stern.
1
Both data sets are treated as tentative. All experimental data points at 298.2 K are reported in
Fig. 43
.
Experimental Data:
(Notes on the Nomenclature)
TABLE 79. Summary of experimental data for the system 2-butanol-cyclohexane-water
Author
T/K
DataType
Reference
Plackov and Stern, 1990
298
sat. (13), eq. (8)
1
Letcher
et al
., 1991
298
sat. (160, eq. (5)
2
TABLE 80. Calculated compositions along the saturation curve at 298.2 K.
T/K
Mole Fraction x
1
Mole Fraction x
2
298.2
0.322
0.000 Ref. 4
298.2
0.3748
0.0100
298.2
0.4172
0.0200
298.2
0.4558
0.0400
298.2
0.4751
0.0600
298.2
0.4863
0.0800
298.2
0.4930
0.1000
298.2
0.4967
0.1200
298.2
0.4983
0.1400
298.2
0.4982
0.1600
298.2
0.4968
0.1800
298.2
0.4943
0.2000
298.2
0.4908
0.2200
298.2
0.4865
0.2400
298.2
0.4815
0.2600
298.2
0.4758
0.2800
298.2
0.4695
0.3000
298.2
0.4626
0.3200
298.2
0.4552
0.3400
298.2
0.4472
0.3600
298.2
0.4388
0.3800
298.2
0.4299
0.4000
298.2
0.4206
0.4200
298.2
0.4108
0.4400
298.2
0.4006
0.4600
298.2
0.3901
0.4800
298.2
0.3791
0.5000
298.2
0.3677
0.5200
298.2
0.3560
0.5400
298.2
0.3438
0.5600
298.2
0.3314
0.5800
298.2
0.3185
0.6000
298.2
0.3053
0.6200
298.2
0.2918
0.6400
298.2
0.2779
0.6600
298.2
0.2637
0.6800
298.2
0.2491
0.7000
298.2
0.2342
0.7200
298.2
0.2190
0.7400
298.2
0.2034
0.7600
298.2
0.1876
0.7800
298.2
0.1714
0.8000
298.2
0.1548
0.8200
298.2
0.1380
0.8400
298.2
0.1208
0.8600
298.2
0.1033
0.8800
298.2
0.0855
0.9000
298.2
0.0674
0.9200
298.2
0.0490
0.9400
298.2
0.0303
0.9600
298.2
0.0000
0.99963 Ref. 3
298.2
0.0000
0.000012 Ref. 3
298.2
0.051
0.0000 Ref. 4
View Figure 1 for this Evaluation
Notes:
Table 79
Number of experimental points in parentheses.
References: (Click a link to see its experimental data associated with the reference)
1
Plackov, D.; Stern, I, Fluid. Phase Equilib. 57, 327 (1990).
2
Letcher, T.M.; Siswana, P.; Radloff, S.E., S. Afr. J. Chem. 44, 118 (1991).
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).