A survey of solubility (soly) and equilibrium of coexisting liquid phases (equil.) for the system nitromethane + heptane + water is given in Table.

Solubility data
All three binary pairs of components, nitromethane + heptane, nitromethane + water and heptane + water, are partially miscible. The data for first two systems were compiled and critically evaluated (Sazonov et al.⁴). The system heptane + water was critically evaluated in Shaw.⁵ The UCST (upper critical solution temperature) binary system nitromethane + heptane has been reported in Zhilyaeva et al.² as 381.5 K and to agree with recommended value in Sazonov et al.⁴
The solubility temperatures of the three and two liquid phases were determined in Zhilyaeva et al.² by the synthetic method in ternary mixtures with constant mass content of heptane, and also in ternary mixtures with a constant mass content of water. The system nitromethane + heptane + water includes a three-phase region. Depending on temperature the system nitromethane + heptane + water forms a miscibility gaps of Type I to III, Treybal.⁶ In the temperature range 273 K to 376.5 K, where three binary systems partially miscible, the solubility curves correspond to Type III (Treybal⁶). A three-phase region occurs below 391.6 K (Zhilyaeva et al.²). Maximal temperature of the three-phase liquid equilibrium was reported to be 391.6 K (Zhilyaeva et al.²) and 395.65 K (Malesinska and Malesinski¹). In the temperature range 376.5 K to 381.5 K ( Fig. 16 ) where two binary systems nitromethane + heptane and heptane + water are partially miscible, the solubility curves correspond to Type II (Treybal⁶). Above 381.5 K this ternary system has only one partially miscible region, Zhilyaeva et al.² Experimental errors were not reported, but are estimated by the evaluator to be ±0.1 K (temperature) and ±0.002 mass fractions (solubility).

Liquid-liquid equilibrium data

Compositions of three coexisting liquid phases for the ternary system nitromethane + heptane + water were reported at 368 K and 378 K in graphical form (Zhilyaeva et al.²), and also at 298.15 K, 303.15 K, 313.15 K, 323.15 K and 333.15 K (Rezanova et al.³). These data are obtained by interpretation of the graphical cloud-point data in Zhilyaeva et al.² and presented in Fig. 16, and also by titration method (Rezanova et al.³). The area of the three-phase region decreases with increasing temperature. Experimental errors were reported in Ref. 3 as ±0.02 K (temperature) and ±0.003 mole fractions (composition).
All experimental data are considered tentative.