A survey of reported compositions along the solubility curve and compositions of coexisting phases in equilibrium for the system nitromethane + ethanol + water is given in Table 1.
Solubility curve
The system nitromethane + ethanol + water forms a miscibility gap of Type I, Treybal.4 Only one binary pair of components, nitromethane + water, is partially miscible. The data for this binary system were previously compiled and critically evaluated5 and are summarized in Table 2.
The solubility of nitromethane in water at 293.2 K reported in Zhuravlev and N. V. Maslovskaya1 and at 313.2 K in Maslovskaya2 are rejected because are inconsistent with recommended values from Savanov et al.5 Data of the solubility nitromethane and water reported in Ref. 3 are consistent with recommended values.
Solubility data obtained by the titration method for the ternary system nitromethane + ethanol + water were reported in three references. The data reported at 313.2 K by Zhuravlev and Maslovskaya1 and by Rezanova et al.3 are in satisfactory agreement, but do not agree with the data at 303 K, from Rezanova et al.3 Therefore, these data were not considered and are not shown in Fig. 6 . The data for the nitromethane + ethanol + water system are consistent with the data for the nitromethane + 1-propanol + water system measured and reported by Maslovskaya in the same paper.2 Experimental errors were reported in Rezanova et al.3 as ( 0.0005 mole fractions. Solubility data1-3 together and separately are described by an algebraic equation in the form
x2 = a + b· x3 + c· (x3)2 + d· (x3)1/2 + e· (x3)3/2.
The proposed equation gives a smaller standard deviation than any other tested equations. The equation parameters (a, b, c, d, e) were calculated by the least squares method and presented in Table 3. Binodal curves in this system were calculated and compared separately for solubility data reported in Zhuravlev and Maslovskaya,2 and Rezanova et al.,3 as well as for the combined data.
The solubility data, as calculated by the proposed equation, are considered tentative and are presented in Fig. 6 and in Table 4. Experimental solubility data1-3 are presented in Fig. 6 for comparison.
Liquid-liquid equilibrium (LLE) data
LLE data for the ternary system nitromethane + ethanol + water were reported in Maslovskaya2 and Rezanova et al.3 Composition of each phase, Maslovskaya,2 was calculated from the index of refraction-composition curve of saturated mixtures prepared at the time of the saturation curve measurements. Compositions of phases in equilibrium reported in Rezanova et al.3 were measured by gas chromatography but detailed experimental procedures are not reported. The tie lines cover the whole range of the miscibility gap. The data reported at 313.2 K by Maslovskaya,2 and Rezanova et al.3 are in agreement. The direction of the tie lines changes with concentration, but is similar in all reported papers. Plait points were reported in Zhuravlev and Maslovskaya1 at 293.2 K (x1 = 0.330, x2 = 0.201) and in Maslovskaya2 at 313.2 K (x1 = 0.451, x2 = 0.168).
Experimental errors were reported only in Rezanova et al.3 to be ± 0.002 mole fractions.
Recommended or tentative data
Solubility and liquid-liquid equilibrium data measured by different methods are in agreement with one another. Experimental data on solubility at all temperatures1-3 are presented in Fig. 6 in mole fractions.
The experimental liquid-liquid equilibrium data at 313.2 K, Maslovskaya2 and Rezanova et al.,3 are used for construction of the smoothed curve for distribution of ethanol between water-rich and nitromethane-rich phases, Fig. 7 . These data also should be considered tentative.