Solid-liquid equilibrium measurements using DSC for three binary mixtures of 2-methylbenzoic acid + 3-methylbenzoic acid, 2-methoxybenzoic acid + 3-methylbenzoic acid, and N-phenylacetamide + benzamide

Abstract

This study reports the solid-liquid equilibrium (SLE) data for three binary mixtures of 2-methylbenzoic acid + 3-methylbenzoic acid, 2-methoxybenzoic acid + 3-methylbenzoic acid, and N-phenylacetamide + benzamide. These phase equilibrium data were measured using the Differential Scanning Calorimetry (DSC). The solidus and liquidus temperatures for each binary mixture at various compositions are presented. All three binary mixtures show the simple eutectic behavior. The eutectic temperatures and compositions for these binary mixtures were determined using the fractional transformation method. The fractional transformation is defined as the fraction of the mixture that is liquefied during the heating process using DSC. The fractional transformation data at the eutectic point, denoted as the eutectic fraction, were evaluated from the experimental DSC results over various time intervals during the measurements. A triangular plot of the eutectic fractions against various compositions of a binary mixture effectively illustrated the eutectic point condition. The liquidus curves for each binary system were correlated using the Wilson and NRTL (Non-Random Two-Liquid) activity coefficient models. The optimally fitted model parameters for each binary mixture are presented in this study. Satisfactory correlation results are also demonstrated for all binary systems.