Liquid–Liquid Equilibrium in Systems with Transesterification of Alcohol (<i>n</i>-Propanol Or <i>n</i>-Butanol)–Ethyl Formate with Deep Eutectic Solvent Based on Choline Chloride at 293.15 and 313.15 K

Deep eutectic solvents (DESs) formed by choline chloride and malonic or glutaric acid were tested for separating azeotropic mixtures. To separate alcohol-ester systems (n-propanol–ethyl formate, n-butanol–ethyl formate), the experimental data of liquid-liquid equilibria (LLE) together with phase diagrams for pseudoternary systems including the DESs were obtained at temperatures of 293.15 and 313.15 K and atmospheric pressure. Liquid–liquid tie lines were determined using NMR spectroscopy and analyzed. Along with LLE data, density and viscosity measurements for the studied DESs in the temperature range of 293.15–353.15 K were carried out. The separation performance of DESs was characterized by distribution coefficients and values of selectivity to alcohol. Comparison of selectivity values in systems containing alcohols and esters and two DESs composed of choline chloride and malonic or glutaric acids was performed. It was found that the studied DESs are capable of catalyzing the transesterification reaction, and the conversion values in the organic phase were determined depending on the alcohol concentration.