A survey of reported compositions along the solubility curve and compositions of coexisting phases in equilibrium for the system nitromethane + toluene + methylcyclohexane is given in Table 1.
Solubility curve
The system nitromethane + toluene + methylcyclohexane forms a miscibility gap of Type I, Treybal.3. Only one binary pair of components, nitromethane + methylcyclohexane, is partially miscible. The data for this system were compiled and critically evaluated (Sazonov et al.4). The tentative values of mutual solubility of the binary nitromethane + methylcyclohexane system at 293 K are: x1″ = 0.013 and x1′ = 0.994. The solubility of nitromethane in methylcyclohexane (0.018 mass fraction; 0,029 mole fraction) and cyclohexane in nitromethane (0.042 mass fraction; 0.027 mole fraction) reported in Kotarski,1 differ from tentative values noticeably, Sazonov et al.4 Binary data reported in Lafyatis et al.2 also differ from tentative values Sazonov et al.4
Solubility data obtained by the titration method for the ternary system nitromethane + toluene + methylcyclohexane were reported in Kotarski.1 Experimental error of titration was reported in the paper as ± 0.005 mL. Solubility data at 293 K (nitromethane-rich and hydrocarbon-rich branches together) are described by an algebraic equation in the form:
x2 = a + b·x3 + c·ln(x3) + d·[ln(x3)]2 + e·(x3)1/2.
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:a= –5.0920, b = –3.6993, c = –1.6341 and d = –0.1647, e = 8.7560; standard deviation of calculated and experimental values is 0.0053 (0.53 %). The binodal curve for this system was calculated and compared to solubility data reported in Kotarski.1 The solubilities calculated by the proposed equation are presented in Table 2 and Fig. 25 .
Liquid-liquid equilibrium (LLE) data
LLE data for the ternary system nitromethane + toluene + methylcyclohexane were reported in both references. Composition of each phase, Kotarski,1 was calculated from the index of refraction-composition curve of the saturated mixtures prepared at the time of the saturation curve measurements. Samples of each phase, Lafyatis et al.,2 were analyzed by gas chromatography. Data reported at 293.2 K, 323.15 K, 348.15 K and 363.15 K, Kotarski1 and Lafyatis et al.,2 are in reasonable agreement. Experimental errors were reported in Lafyatis et al.2 : the discrepancy between 2 determinations always less than 0.005 mole fraction. The critical solubility point was presented only in Kotarski1 to be x1 = 0.520, x2 = 0.280 at 293.2 K.
All experimental data are considered tentative.