Thermodynamic Modeling of Time-Dependent Interfacial Properties in Reactive Liquid–Liquid Systems Close to the Critical Point

In liquid–liquid systems, inhabiting an autocatalyzed chemical equilibrium reaction, the catalyst can additionally act as a solubilizer. Therefore, depending on the time-dependent amount of catalyst present in the system, the mixture can get close to the critical point. This may affect the interfacial properties tremendously, up to a point where the interface vanishes completely, if the critical point is actually reached. If so, the mixture changes from heterogeneous to homogeneous by means of the progressing reaction itself. The purpose of this work is to predict interfacial properties in the reactive liquid–liquid system water + 1-hexanol + hexylacetate + acetic acid. The reaction taking place is the autocatalyzed esterification reaction 1-hexanol + acetic acid ↔ hexylacetate + water. To describe the kinetics of this reaction, rate equations based on activities were applied. By combining these differential rate equations with the incompressible version of the density gradient theory (inc-DGT), the time-...