Solid–Liquid Phase Equilibria, Molecular Interaction and Microstructural Studies on (N-(2-ethanol)-p-nitroaniline + N-(2-acetoxyethyl)-p-nitroaniline) Binary Mixtures

Abstract

Differential scanning calorimetry (DSC) is used to investigate the thermal properties of N-(2-ethanol)-p-nitroaniline + N-(2-acetoxyethyl)-p-nitroaniline, and their binary systems. The experimental results demonstrate that the studied binary system presents a simple eutectic behavior and the corresponding mole fraction (x eu) of N-(2-ethanol)p-nitroaniline at the eutectic point is 0.5486, whereas the temperature (T eu) is found to be equal to 363.6 K. The quality of the solid-liquid equilibria (SLE) data has been checked by thermodynamic consistency tests, presenting good quality factor. The SLE data have been correlated by means of Wilson, NRTL, and UNIQUAC equations. The three models describe satisfactorily the phase diagram as the root-mean-square deviations for the equilibrium temperatures vary from 1.25 K to 2.07 K. Nevertheless, the Wilson model provides the best correlation results. The three equations have also been used to compute excess thermodynamic functions viz. excess Gibbs energy, enthalpy and entropy. The obtained results revealed a sensitive positive deviation to ideality thus demonstrating the nature of the interactions between the compounds forming the mixture. Microstructural studies have been carried out by FTIR, XRD and optical microscopy showing weak molecular interactions for the eutectic mixture.

Characterization and Testing for Lowest Eutectic Mixture of TNBA/DNTF

“…The characteristic peaks at 2878 cm −1 and 3094 cm −1 were due to the vibrations of Ar−O−CH 3 in the raw material TNBA and the C−H bond for hydrogen atoms connected to the benzene ring. We confirmed that the lowest eutectic (Figure 6(a)) for the TNBA/DNTF system showed all of the peaks for the pure components without translations, shape modification, absences, shifts or broadening of the characteristic bands; no new peaks were observed, indicating very weak intermolecular interactions between the two components of the lowest eutectic [31–33].…”

“…In fact, the X-ray patterns of the lowest eutectic exhibited all the peaks of the pure compounds. The slight variations in the relative intensities of reflections for the pure components in the lowest eutectic can be explained by weak intermolecular interactions between the components of the eutectic [32,33].…”

Experimental Investigation and Modeling of Cocrystal Formation in L-Menthol/Thymol Eutectic System

“…According to the DSC curves shown in Figure A, it is highly probable that the second solid is a cocrystal with a stoichiometric ratio of 3:2 for l -menthol:thymol (3:2 cocrystal). An analysis of the powder XRD patterns and the DSC curves in Figure shows that the solidus peaks at x thymol = 0.50 and 0.33 with onset temperatures of 271.6 and 272.7 K, respectively, represent the two eutectic points of the system. − …”

Experimental Measurements and Thermodynamic Modeling of Melting Temperature of the Binary Systems n-C11H24–n-C14H30, n-C12H26–n-C13H28, n-C12H26–n-C14H30, and n-C13H28–n-C15H32 for Cryogenic Thermal Energy Storage

“…The theoretical calculation results were almost consistent with previous experimental data. Trache et al and Chelouche et al , investigated the solid–liquid equilibria for six binary organic mixtures and observed the simple eutectic behaviors for these systems. The Wilson, NRTL, and the UNIQUAC models were employed in correlating the experimental results.…”