Experimental high-temperature, high-pressure (HTHP) density of three solvents including dimethyl sulfoxide, benzyl alcohol, and isoamyl acetate was measured at temperatures of 293.15–473.15 K and pressures up to 35–37.5 MPa. The density was measured with an Anton Paar density meter (DMA HP) at 20 K and 2.5 MPa intervals. The calibration fluids were water and benzene. The combined expanded uncertainty of density taking into account the device specification and the impurities of the materials was 1 kg·m–3 (0.95 level of confidence). The experimental density data were correlated with the Tait and new modified Tait equations. The thermal expansion coefficient (α p ) and isothermal compressibility (κ T ) were calculated with the new modified Tait equations. Moreover, the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state was used to model the density data at HTHP. In most cases, the PC-SAFT parameters are obtained from saturated vapor pressure and liquid phase density; however, these parameters were calculated from the density at HTHP in the present study. Regarding these parameters, thermodynamic properties such as the thermal expansion coefficient (α p ), isothermal compressibility (κ T ), isobaric heat capacity (C P ), and speed of sound (u) were calculated. Acceptable agreement between the results with experimental data demonstrated the accuracy of modeling with the obtained parameters.

New experimental densities for diethylamine (DEA), dibutylamine (DBA), and tributylamine (TBA) at 11 isotherms in the range of 293.15–473.15 K and 18 isobars up to 37.5 MPa are reported. PρT measurements (176 experimental data points) have been performed using a high-pressure vibrating-tube densimeter. These data were correlated with a new modified Tait-like equation considering standard deviations of less than 2 × 10–4 g·cm–3, and then isothermal compressibility (κT) and thermal expansion coefficient (αP) were calculated. This study is supported by the results of modeling using the perturbed-chain statistical associating fluid theory (PC-SAFT). The parameters of PC-SAFT equation of state (EoS), for pure solvents, were rigorously determined by fitting the equation to the liquid PρT experimental data. In this study, the correlations, which are based on minimizing the total objective functions (density, pressure, and temperature) simultaneously, were developed to estimate the PC-SAFT parameters. The model reasonably predicted the behavior of PρT and the first- and second-derivative properties such as isothermal compressibility (κT), thermal expansion coefficient (αP), isobaric heat capacities (C P), and speed of sound (u). The results undoubtedly suggest that the model performance is enhanced for either cases of the new modified Tamman–Tait equation and the PC-SAFT EoS, based on employing the proposed parameters.