2-Propanol with Toluene 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 2-propanol-toluene-water is given in Table 62.

Saturation curve
The ternary system 2-propanol-toluene-water forms a miscibility gap of type 1. The system was measured at 293 K, 298 K, and at boiling temperatures at 101.3 kPa. Only toluene-water binary system forms a miscibility gap. The data of this binary system were compiled and critically evaluated in a previously published SDS volume.6 The recommended values of mutual solubility of toluene-water system at 298 K are x'2=0.9972 and x"2=0.000 104.6 This critical evaluation is based on the original papers with the exception of data of Liekola,1 which were taken from the handbook of Kafarov,7 this data set was also taken into account during evaluation but is not reported as a compilation sheet because it does not contribute further to knowledge of the system. At 293 K the experimental data of Borisova et al.4 present a slightly larger miscibility gap than those of Stankova et al.3 which are very close to the results at 298 K. The data for the saturation curve are consistent within each data set, as well as with one another. The miscibility gap decreases with increasing temperature. A maximum value of 2-propanol concentration on saturation curve observed at 298 K is equal to x1=0.39±0.01 (differences between data sets, Refs. 2.5 are about 0.02 mole fraction). The saturation curve was described by the equation proposed by Hlavaty8 and used also with success by Letcher et al.9 for the description of saturation curves of ternary systems containing alcohols
x1=a1·z1·ln(z1)+a2·z2 ln(z2)+a3·z1·z2,
where z1=(x2+0.5·x1-x"20)/(x'20-x"20), z2=(x'20-x2-0.5·x1)/(x'20-x"20), x1, x2-mole fractions of component (1) and (2), respectively, x'20, x"20-values of x2 on the saturation curve which cuts the x1=0 axis.
All experimental compositions on the saturation curve at 298.2 K (compositions of tie lines were included), Refs. 2 and 5, as well as the “best” mutual solubility values of the binary system, Ref. 6, were used in the calculations. The parameters calculated by the least-squares method are: a1=-0.319 92, a2=-0.005 56, a3=1.107 75. The standard error of estimate was 0.0071. The compositions of the saturation curve calculated by the proposed equation at 298.2 K are presented in Table 63 and in Fig. 32 .

Phases in equilibrium
The phases in equilibrium were measured also at 293 K, 298 K, and at boiling temperatures at 101.3 kPa. The tie lines cover the whole area of miscibility gap. They are consistent within each data set, as well as with one another. However, the tie lines reported at 298.2 K,2,5 cross slightly as could be noticed if a large scale graph were plotted. The tie lines are treated as tentative.
The plait point of the system changes with temperature. At 293.2 K it was reported to be x1=0.292, x2=0.069, (Ref. 4) at 298.2 K-x1=0.27, x2=0.07 (Ref. 5) while at 101 kPa at boiling temperature (348.9±0.1 K) it was estimated by the evaluator to be x1=0.370±0.004, x2=0.209±0.001.
TABLE 63. Calculated compositions along the saturation curve at 298.2 K
C $T$ ($\pu{K}$) D $x_{1}$ D $x_{2}$
298.2 0.0 1.04 x 10-4
298.2 1.982 x 10-1 2.00 x 10-2
298.2 2.479 x 10-1 4.00 x 10-2
298.2 2.828 x 10-1 6.00 x 10-2
298.2 3.093 x 10-1 8.00 x 10-2
298.2 3.300 x 10-1 1.000 x 10-1
298.2 3.464 x 10-1 1.200 x 10-1
298.2 3.594 x 10-1 1.400 x 10-1
298.2 3.696 x 10-1 1.600 x 10-1
298.2 3.774 x 10-1 1.800 x 10-1
298.2 3.833 x 10-1 2.000 x 10-1
298.2 3.874 x 10-1 2.200 x 10-1
298.2 3.900 x 10-1 2.400 x 10-1
298.2 3.912 x 10-1 2.600 x 10-1
298.2 3.912 x 10-1 2.800 x 10-1
298.2 3.901 x 10-1 3.000 x 10-1
298.2 3.879 x 10-1 3.200 x 10-1
298.2 3.848 x 10-1 3.400 x 10-1
298.2 3.809 x 10-1 3.600 x 10-1
298.2 3.761 x 10-1 3.800 x 10-1
298.2 3.706 x 10-1 4.000 x 10-1
298.2 3.645 x 10-1 4.200 x 10-1
298.2 3.576 x 10-1 4.400 x 10-1
298.2 3.502 x 10-1 4.600 x 10-1
298.2 3.421 x 10-1 4.800 x 10-1
298.2 3.336 x 10-1 5.000 x 10-1
298.2 3.245 x 10-1 5.200 x 10-1
298.2 3.149 x 10-1 5.400 x 10-1
298.2 3.049 x 10-1 5.600 x 10-1
298.2 2.944 x 10-1 5.800 x 10-1
298.2 2.835 x 10-1 6.000 x 10-1
298.2 2.722 x 10-1 6.200 x 10-1
298.2 2.605 x 10-1 6.400 x 10-1
298.2 2.484 x 10-1 6.600 x 10-1
298.2 2.360 x 10-1 6.800 x 10-1
298.2 2.232 x 10-1 7.000 x 10-1
298.2 2.101 x 10-1 7.200 x 10-1
298.2 1.967 x 10-1 7.400 x 10-1
298.2 1.830 x 10-1 7.600 x 10-1
298.2 1.689 x 10-1 7.800 x 10-1
298.2 1.546 x 10-1 8.000 x 10-1
298.2 1.401 x 10-1 8.200 x 10-1
298.2 1.252 x 10-1 8.400 x 10-1
298.2 1.101 x 10-1 8.600 x 10-1
298.2 9.48 x 10-2 8.800 x 10-1
298.2 7.92 x 10-2 9.000 x 10-1
298.2 6.33 x 10-2 9.200 x 10-1
298.2 4.73 x 10-2 9.400 x 10-1
298.2 3.10 x 10-2 9.600 x 10-1
298.2 1.44 x 10-2 9.800 x 10-1
298.2 0.0 9.972 x 10-1

Figure
Solubility graph
Sources:

8 Hlavaty, K.; Collect. Czech. Chem. Commun. 37, 4005 (1972).
1 Leikola, E.; Suomen Kemistil B. 13, 13 (1940).
2 Washburn, E. R.; Brockway, C. E.; Graham, C. L.; Deming, P.; J. Am. Chem. Soc. 64, 1886 (1942).
3 Staňková, L.; Veselý, F.; Pick, J.; Collect. Czech. Chem. Commun. 35, 1 (1970).
4 Borisova, I. A.; Vatskova, V. G.; Gorbunov, A. I.; Sokolov, N. M.; Khim. Prom. 347 (1978).
5 Letcher, T. M.; Siswana, P. M.; Fluid Phase Equilib. 74, 203 (1992).
6 Shaw, D. G.; 'Hydrocarbons with Water and Seawater, Part I: Hydrocarbons C5 to C7' IUPAC Solubility Data Series, 1989, Vol. 37, Pergamon Press.
7 Kafarov, V. V.; ed.; Spravochnik po Rastvorimosti Vol. 2, Troinye, Mnogokomponentnye Sistemy, Kniga II (Izd. Akademii Nauk USSR, Moskva, 1963).
9 Letcher, T. M.; Ravindran, S.; Radloff, S. E.; Fluid Phase Equilib, 69, 251 (1991).