Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Diethyl citrate was synthesized and isolated to obtain the first set of thermodynamic data of this component. It was synthesized by partial esterification of citric acid with ethanol. The final product was separated from the resulting mixture using a pH controlled solvent extraction method. Characterization using 1H NMR and 13C NMR spectroscopy confirmed the presence of both DEC isomers with few impurities. Results indicate that a 6:5 molar ratio of the symmetric to the non-symmetric ester structures was attained during synthesis. Thermogravimetric analysis and differential scanning calorimetry allowed to measure for the first time the diethyl citrate melting temperature (234 K); its decomposition temperature (493 K); and the heat capacity dependence with temperature (1.25-1.45 kJ/kg K) in the range of 300-390 K. Additionally, P-x data for the vapor-liquid equilibrium of the binary mixtures diethyl citrate + ethanol and diethyl citrate + water were collected at 308 K using an accurate dynamic device. Data were regressed to generate binary interaction parameters for the UNIQUAC equation. The regressed model shows good agreement, and it can be used for further process design in the esterification of citric acid.