In this work, bubble point pressures of the system of methanol + methyl propionate were measured for several isopleths within temperature and pressure ranges of 382-444 K and 0.437-2.285 MPa, respectively. The vapor pressures of pure methanol and methyl propionate were also measured. The two-suffix Margules equation was used to represent the nonidealities of the liquid phase and the virial equation of state was used to take into account the nonidealities of the vapor phase. The temperature-dependent parameter of the two-suffix Margules equation was determined using Barker's method. The results show that the model can successfully estimate the bubble points of this system with average errors less than 0.69%.

In continuation of our earlier publication on the phase behavior of binary and ternary mixtures involving acetaldehyde, Versatic 10, and Veova 10, in this work we present bubble-point pressures of the binary and ternary systems of acetaldehyde, Versatic 9, and Veova 9. The measurements were carried out in the Cailletet equipment, which operates according to the synthetic method. The solubility data are presented within a temperature range of 298-353 K for the two binaries of acetaldehyde + Versatic 9 and acetaldehyde + Veova 9. The pressures required for complete solubility into one homogeneous phase ranged from 0.083 to 0.414 MPa in the temperature and concentration range considered. While both Versatic and Veova contain a C=O group, Versatic also contains an alcoholic OH, which makes its solubility in acetaldehyde more difficult. The solubility curve of Versatic 9 not only shifts to higher pressures compared to that of Veova 9, but also has an increased curvature, indicating its greater deviations from ideality. As the alkyl chain is increased by one carbon number to Veova 10 and Versatic 10, the absence and presence of the OH group in Veova and Versatic also result in greater and smaller curvatures of the solubility curves, respectively. The Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) equations of state were used to model phase equilibria of the binary systems of acetaldehyde + Versatic 9 and acetaldehyde + Veova 9. Results showed that both models have good agreement with the experimental values in this study. Two ternary mixtures of acetaldehyde + Versatic 9 + Veova 9 were also investigated experimentally for their bubble point pressures. While both components have one C=O group, Versatic 9 also contains an alcoholic OH, which Veova 9 lacks. Therefore, nonideal interactions are increased between the molecules of acetaldehyde and Versatic 9 due to the presence of this hydrogen-bonding group, as compared to the system of acetaldehyde + Veova 9.