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Vapor pressures of propyl acetate, 1-butanol and 2-butanol and the isobaric (vapor + liquid) equilibrium of n-propyl acetate with 1-butanol at 0.1, 0.15 and 0.6 MPa as well as n-propyl acetate with 2-butanol at 0.15 and 0.6 MPa was investigated using a dynamic stainless steel ebulliometer. The experimental data for the binary systems were tested and verified to be thermodynamically consistent by the point-to-point test of Van Ness. Different thermodynamic–mathematical equations together with several activity coefficient models were used to correlate the experimental data. The average absolute deviations for the vapor phase compositions are all below 0.01. In addition, the ASOG and three versions of UNIFAC group contribution models were used to estimate the (vapor + liquid) equilibrium data. The UNIFAC-Dortmund globally generated the best predictions. The mean error in the activity coefficient was less than 7%. For the n-propyl acetate (1) + 1-butanol (2) system an azeotrope has been verified at 0.15 MPa (x1azexp = y1azexp = 0.949 and Tazexp = 387.61 K) and at 0.6 MPa (x1azexp = y1azexp = 0.783 and Tazexp = 445.68 K) while for the n-propyl acetate (1) + 2-butanol (2) system, the azeotrope at 0.15 MPa was found at x1azexp = y1azexp = 0.331 and Tazexp = 383.03 K and was not detected at 0.6 MPa.

Data from isobaric vapor–liquid equilibrium (VLE) for the binary systems methyl acetate, ethyl acetate, and n-propyl acetate with 1-propanol have been determined at 0.6 MPa employing a metal ebulliometer with recirculation of both phases. The thermodynamic consistency of experimental data has been verified with the Van Ness point-to-point test, using the routine in Fortran proposed by Fredenslund et al. The azeotropic point was observed for the binary systems ethyl acetate/1-propanol and propyl acetate/1-propanol. The activity coefficients of the liquid phase were calculated by considering the nonideality of the vapor phase. The binary systems studied show positive deviation from ideal behavior. Predictions obtained from the group contribution models ASOG and different versions of UNIFAC were verified by comparing the values provided by the models with experimental data of VLE.

The vapour pressures of n-propyl acetate, iso-butyl acetate and 2-pro- panol from 0.004 to 1.6 MPa absolute pressure and vapour-liquid equilibria (VLE) data for the binary systems n-propyl acetate+ethanol, n-propyl ace- tate+2-propanol, iso-butyl acetate+ethanol and iso-butyl acetate+2-propanol at 0.15 MPa were determined. The experimental VLE data were verified with the van Ness Test and the Fredenslund Criterion. The n-propyl acetate+ethanol and +2-propanol binary systems have an azeotropic point at 0.15 MPa. Different versions of the universal quasichemical functional group activity coefficients and analytical solutions of groups contribution models were applied.