Density, dynamic viscosity, and saturated vapor pressure of four difluoroaniline isomers at different temperatures and atmospheric pressure

Difluoroanilines are key fine chemical intermediates, widely used in dyestuff, pharmaceutical, and pesticides, but literature on their thermophysical properties remains limited. In this work, experimental measurements of thermophysical properties were carried out for four pure difluoroaniline isomers (2,6-difluoroaniline, 2,4-difluoroaniline, 2,5-difluoroaniline, and 3,4-difluoroaniline) at atmospheric pressure over defined temperature ranges: density (293.15–353.15 K), dynamic viscosity (293.15–353.15 K), and saturated vapor pressure (336–465 K). For each isomer, 13 data points were collected for density, 13 data points for dynamic viscosity (11 points for 3,4-difluoroaniline due to bubble formation above 343.15 K), and 22 data points for saturated vapor pressure. The instrumental uncertainties are: temperature (±0.02 K for density, ±0.005 K for dynamic viscosity, ±0.1 K for saturated vapor pressure), pressure (±0.2 kPa), density (±5 × 10 −5  g/cm 3 ), and dynamic viscosity (0.1 % relative standard uncertainty). The density-temperature dependence was successfully correlated using the DIPPR equation. Meanwhile, dynamic viscosity data were analyzed via the Litovitz, Ghatee, VFT, and Andrade models, among which the VFT model yielded the most accurate predictions. Furthermore, the Antoine and Riedel equations facilitated precise correlation of saturated vapor pressure with temperature. Additionally, the isobaric thermal expansion coefficient was derived from the density dataset, and the molar vaporization enthalpies of four of the target isomers were estimated employing the Clausius-Clapeyron equation. Collectively, the thermophysical properties of these pure components are crucial for the development and optimization of separation processes involving the four difluoroaniline isomers.