A survey of reported compositions along the saturation curve (sat), and compositions of coexisting phases in equilibrium (eq.) and distribution of ethanol between phases (distr.) for the system ethanol-toluene-water is given in Table 25.

Saturation curve The ternary system ethanol-toluene-water forms a miscibility gap of type 1. There are 12 references for this system over the temperature range 243-353 K. This evaluation was made on the basis of original papers with the exception of data of Ormandy and Craven,³ Tarasenkov and Polozhentseva,⁴ and Leikola,⁶ which were taken from the handbook of Kafarov,¹³ these data were also taken into account during evaluation but are not reported as compilation sheet because they do not contribute further to knowledge of the system. Only the binary system toluene-water is partially miscible. The data for this system were compiled and critically evaluated in a previously published SDS volume.¹⁴ The recommended values of mutual solubility at 298 K are x'₂=0.9972 and x"₂=0.000 0104. The papers of Borisova et al.,⁹ (x'₂=0.9976 and x"₂=0.0001 at 293.2 K) and Letcher and Siswana,¹² (x'₂=0.999 and x"₂=0.000 at 298.2 K) report mutual solubility of the binary system. Accuracy of experimental data reported in Ref. 12 was stated by the authors to be 0.005 mole fraction, so these data are consistent. The water-rich phase, Ricna et al.¹¹ is reported to be toluene free over a wide range of temperatures and water concentrations. This indicates that their experimental accuracy was in the range of 0.001-0.005 mole fraction; lower than reported (0.001 mole fraction). Data of Arzhanov et al.⁹ reported for the temperature range 348-347 K describe the vapor-liquid-liquid equilibrium. (The boiling temperatures of two-phase mixture of Ref. 8 were estimated from authors graph.) The point (x₁=0.5536 and x₂=0213) on saturation curve at 278.2 K, Rican et al.¹¹ appears to contain a typing error and is rejected. Data reported for 273.2, 293.2, 313.2 K by Tarasenkov and Polozhentseva⁴ contain errors for the toluene-rich phase; the experimental points are inconsistent with saturation curve in the region of low concentration of ethanol. These data are also rejected. Data of Borisova et al.⁹ at 293.2 K close to the plait point, show a miscibility gap similar to the data at 273 K and larger than data of Leikola.⁶ All other data for the saturation curve are consistent with one another. Ormandy and Craven³ reported seven isotherms which clearly show the temperature dependence of the saturation data in the range 243-303 K. Characteristic points of the binodal curve of the system ethanol-toluene-water at selected temperatures, reported in literature, are presented in Table 26. At the maximum ethanol concentration point, the errors estimated by the evaluator are to be 0.005 and 0.015 mole fraction of ethanol and benzene, respectively.
The temperature of 298.2 K was selected to present the behavior of the system. All experimental saturation and equilibrium points at 298.2 K water-rich and benzene-rich branches together, were described by the equation: x₁=0.718 83+0.092 81 ln(x₂)-0.488 76x₂-0.230 41x²₂. The least-squares method was used and the standard error of estimate was 0.0125. The compositions on the saturation curve calculated by the proposed equation are presented in Table 27 for selected concentrations to toluene in the mixture. The results of calculations (solid line) are also presented graphically in Figure 14 together with all experimental data reported at 298.2 K.

Phases in equilibrium Compositions of the coexisting phases in equilibrium for the ternary system ethanol-toluene-water were reported in six references over the temperature range 273-357 K as 11 data sets. Two of these data sets, of Arzhanov et al.,⁸ and Borisova et al.,⁹ were measured at the boiling temperatures of two-phase mixtures at atomospheric pressure. Data reported by Tarasenkov and Polozhentseva⁴ contain errors in the toluene-rich phase, as discussed above, and are rejected. Equilibrium phases for a boiling point of 248.2 K, Borisova et al,⁹ contain presumably an analytical error. This tie line is inconsistent within the data set; other tie lines at boiling temperatures, Refs. 8 and 9, are consistent and cover the full miscibility gap. Other reported data are consistent within each data set. The distrbution of ethanol (direction of tie lines) between the phases changes with temperature and at the boiling point (348-357 K) the concentration of ethanol in both phases becomes nearly the same. The reported plait points are presented above in Table 2. All equilibrium data are treated as tentative. All experimental points at 298.2 K, both saturation and equilibrium data, ^{3,5,7,10,11,12,} are presented in Figure 14 .