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IUPAC-NIST Solubility Database
NIST Standard Reference Database 106
Solubility System:
Methanol with Cyclohexane and Water
Components:
(1) Water; H2O; [7732-18-5]
NIST Chemistry WebBook
for detail
(2) Cyclohexane; C6H12; [110-82-7]
NIST Chemistry WebBook
for detail
(3) Methanol (methyl alcohol); CH4O; [67-56-1]
NIST Chemistry WebBook
for detail
Evaluator:
A. Skrzecz, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland (1996.04)
Critical Evaluation:
A survey of reported compositions along the saturation curve (sat.), compositions of coexisting phases in equilibrium (eq.) and distribution of methanol between phase (dist.) for the system methanol-cyclohexane-water is given in Table 6.
Saturation curves
The system methanol-cyclohexane-water forms a large miscibility gap of type 2 covering the majority of the concentration triangle. Two binary systems, cyclohexane-water and cyclohexane-methanol, form miscibility gaps. The data of these binary systems were compiled and critically evaluated in previously published SDS volumes, Refs. 5 and 6, respectively. The recommended values
5
of mutual solubility of the cyclohexane-water system at 298.2 K are
x
"
2
=1.2·10
–5
and
x
'
3
=3.7·10
–4
. The mutual solubility at 298.2 K and upper critical solubility temperature of the methanol-cyclohexane system calculated on the basis of Ref. 6 are
x
'
1
=0.128 and
x
"
1
=0.822 and 318.7 K. Reported data on the saturation curves describe mainly the cyclohexane poor phase; there are few experimental points in the cyclohexne-rich region. Data for both temperatures are in agreement with one another with the exception of the Washburn and Spencer data
1
in the cyclohexane-rich phase, which presents too high concentration of water. All experimental solubility and equilibrium data at 298 K in cyclohexane-poor phase
1,3,4
were described by the equation:
x
1
1.07468+0.05543 ln(
x
3
–1.07833
x
3
.
The parameters were calculated by the least-squares method and the standard error of estimate was 0.0030. The equation is valid in the region of 0.02<
x
3
<0.50. The points on the saturation curve calculated by the above equation for the selected concentrations of water in the mixture together with the recommended data of binary systems are presented in Table 7 and in
Figure 3
as a solid line.
Phases in equilibrium
Compositions of coexisting phases in equilibrium for the ternary system methanol-cyclohexane-water were reported in Refs. 2, 3, and 4. In Ref. 1 the distribution of methanol between two phases (hydrocarbon-rich and hydrocarbon-poor) was reported. The lines reported by Letcher
et al
.
3
were measured at the pressure of 94.7
k
Pa, but the influence of such pressure difference (6.6
k
Pa) on liquid-liquid equilibria may be neglected. The experimental tie lines of Budantseva
et al
., Ref. 2, even they were measured at 293.2 K, are in agreement with tie lines of Plackov and Stern,
4
measured at a little higher temperature of 298.2 K. The three tie lines presented by Letcher
et al
.
3
were measured with the accuracy 0.01 mole fraction, as was reported in the paper and are not consistent with data of Ref. 4. Therefore data of Plackov and Stern,
4
in the opinion of evaluator, appear reliable and are considered as tentative. They are presented in
Figure 3
.
Experimental Data:
(Notes on the Nomenclature)
TABLE 6. Summary of experimental data for the system methanol-cyclohexane-water
Author
T/K
DataType
Reference
Washburn and Spencer, 1934
298
sat. (16), dist. (6)
1
Budantseva
et al
., 1976
293
eq. (10)
2
Letcher
et al
., 1991
298
sat. (12), eq. (3)
3
Plackov and Stern, 1992
298
sat. (14), eq. (7)
4
TABLE 7. Calculated compositions along the saturation curve at 298.2 K
T/K
Mole Fraction x
1
Mole Fraction x
3
298.2
0.822
0.718 Ref. 6
298.2
0.8363
0.0200
298.2
0.8531
0.0400
298.2
0.8540
0.0600
298.2
0.8484
0.0800
298.2
0.8392
0.1000
298.2
0.8278
0.1200
298.2
0.8147
0.1400
298.2
0.8006
0.1600
298.2
0.7855
0.1800
298.2
0.7698
0.2000
298.2
0.7535
0.2200
298.2
0.7368
0.2400
298.2
0.7197
0.2600
298.2
0.7022
0.2800
298.2
0.6844
0.3000
298.2
0.6665
0.3200
298.2
0.6483
0.3400
298.2
0.6299
0.3600
298.2
0.6113
0.3800
298.2
0.5926
0.4000
298.2
0.5737
0.4200
298.2
0.5547
0.4400
298.2
0.5356
0.4600
298.2
0.5164
0.4800
298.2
0.4971
0.5000
298.2
0.0000
0.999988 Ref. 5
298.2
0.0000
0.00037 Ref. 5
298.2
0.128
0.0000 Ref. 6
View Figure 1 for this Evaluation
Notes:
Table 6
Number of experimental points in parentheses.
References: (Click a link to see its experimental data associated with the reference)
1 Washburn, E.R., Brockway, C.E.; Graham, C.L.; Deming, P., J. Am. Chem. Soc. 64, 1886 (1942).
2
Budantseva, L.S.; Lesteva, T.M.; Nemstov, M.S., Zh. Fiz. Khim. 1976, 50, 1344. Deposited doc. 1976, VINITI 437-76.
3
Letcher, T.M.; Siswana, P.; Radloff, S.E., S. Afr. J. Chem. 44, 118 (1991).
4
Plackov, D.; Stern, I., Fluid. Phase Equilib. 71, 189 (1992).
5 Shaw, D.G., ed., Solubility Data Series, Vol. 37, Hydrocarbons with Water and Seawater, Part I: Hydrocarbons C5 to C7 (Pergamon, New York, 1989).
6 Shaw, D.G.; Skrzecz, A.; Lorimer, J.W.; Maczynski, A., eds., Solubility Data Series, Vol 56, Alcohols with Hydrocarbons (Pergamon, New York, 1994).