1-Butanol with n-Hexane and Water (IUPAC SDS Volume 69)
Evaluator
Adam Skrzecz Institute of Physical Chemistry, Polish Academy of Sciences
Evaluation
A survey of reported compositions along the saturation curve (sat), and compositions of coexisting phases in equilibrium (eq.) for the system 1-butanol-hexane-water is given in Table 75.

Saturation curve
The ternary system 1-butanol-hexane-water forms a miscibility gap of type 2. The system was studied by the titration method in both cases and is presented below at 298.2 K. Two binary systems, hexane-water and 1-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 hexane-water system x"2=2.3·10-6 and x'2=0.999 53, Ref. 3, and for 1-butanol-water system x'1=0.488 and x"1=0.0191, Ref. 4. The solubility of water in hexane, reported by Sugi and Katayana1 (x'2=0.99949) is consistent with recommended value of Ref. 3, while mutual solubility of 1-butanol-water system (x"1=0.0151 and x'1=0.5032) differ a little from recommended data, Ref. 4. Both data sets measured at various temperatures are mutually consistent and are treated as tentative. Compositions of water-rich phase were reported as hexane free in Ref. 1 and therefore this branch cannot be evaluated. The organic-rich phase data of Ref. 1 (saturation and equilibrium data together) were described by the equation:
x1=0.694 76+0.046 08 ln(x2)-0.404 41x2-0.283 19x22.
The model applies to the region 0.03<x2<0.86, as data reported in Ref. 1. The parameters were calculated by the least-squares method. The standard error of estimate was 0.0017. The points on the saturation curve calculated by the above equation for selected concentrations of hexane in the mixture are presented in Table 76 and in Figure 40 as a calculated binodal curve (solid line).

Phases in equilibrium
Compositions of coexisting phases in equilibrium for the ternary system 1-butanol-hexane-water were reported only by Sugi and Katyana.1 Concentration of hexane in the water-rich phase in equilibrium was assumed to be 0.0. The tie lines cover the whole area of the miscibility gap and are consistent within data set. Consequently they are treated as tentative. All experimental data points at 298.2 K are shown in Figure 40 .
TABLE 76. Calculated compositions along the saturation curve 298.2 K
C $T$ ($\pu{K}$) D $x_{1}$ D $x_{2}$
298.2 4.88 x 10-1 0.0
298.2 5.208 x 10-1 3.00 x 10-2
298.2 5.298 x 10-1 4.00 x 10-2
298.2 5.398 x 10-1 6.00 x 10-2
298.2 5.442 x 10-1 8.00 x 10-2
298.2 5.454 x 10-1 1.000 x 10-1
298.2 5.445 x 10-1 1.200 x 10-1
298.2 5.420 x 10-1 1.400 x 10-1
298.2 5.384 x 10-1 1.600 x 10-1
298.2 5.338 x 10-1 1.800 x 10-1
298.2 5.284 x 10-1 2.000 x 10-1
298.2 5.223 x 10-1 2.200 x 10-1
298.2 5.156 x 10-1 2.400 x 10-1
298.2 5.084 x 10-1 2.600 x 10-1
298.2 5.007 x 10-1 2.800 x 10-1
298.2 4.925 x 10-1 3.000 x 10-1
298.2 4.838 x 10-1 3.200 x 10-1
298.2 4.748 x 10-1 3.400 x 10-1
298.2 4.654 x 10-1 3.600 x 10-1
298.2 4.556 x 10-1 3.800 x 10-1
298.2 4.455 x 10-1 4.000 x 10-1
298.2 4.350 x 10-1 4.200 x 10-1
298.2 4.242 x 10-1 4.400 x 10-1
298.2 4.130 x 10-1 4.600 x 10-1
298.2 4.016 x 10-1 4.800 x 10-1
298.2 3.898 x 10-1 5.000 x 10-1
298.2 3.778 x 10-1 5.200 x 10-1
298.2 3.654 x 10-1 5.400 x 10-1
298.2 3.528 x 10-1 5.600 x 10-1
298.2 3.398 x 10-1 5.800 x 10-1
298.2 3.266 x 10-1 6.000 x 10-1
298.2 3.131 x 10-1 6.200 x 10-1
298.2 2.994 x 10-1 6.400 x 10-1
298.2 2.853 x 10-1 6.600 x 10-1
298.2 2.710 x 10-1 6.800 x 10-1
298.2 2.565 x 10-1 7.000 x 10-1
298.2 2.416 x 10-1 7.200 x 10-1
298.2 2.265 x 10-1 7.400 x 10-1
298.2 2.112 x 10-1 7.600 x 10-1
298.2 1.956 x 10-1 7.800 x 10-1
298.2 1.797 x 10-1 8.000 x 10-1
298.2 1.636 x 10-1 8.200 x 10-1
298.2 1.472 x 10-1 8.400 x 10-1
298.2 1.306 x 10-1 8.600 x 10-1
298.2 0.0 9.9953 x 10-1
298.2 0.0 2.3 x 10-6
298.2 1.91 x 10-2 0.0

Figure
Solubility graph
Sources:

1 Sugi, H.; Katayama, T.; J. Chem. Eng. Jpn. 1977, 10, 400-2.
2 Morozov, A. V.; Sarkisov, A. G.;Turovskii, V. B.; Ilyaskin, V. I.; Dep. Doc. VINITI 102-78, 1 (1978).
3 Shaw, D. G.; 'Hydrocarbons with Water and Seawater, Part I: Hydrocarbons C5 to C7' IUPAC Solubility Data Series, 1989, Vol. 37, Pergamon Press.
4 Barton, A. F. M.; ed.; Solubility Data Series, Vol. 15, Alcohols with Water (Pergamon, New York 1984).