Density and viscosity of binary mixtures of diethyl oxalate with ethanol, ethyl acetate, tetrahydrofuran, and toluene

Abstract

ABSTRACTThis study presents the densities and viscosities of four binary liquid mixtures containing diethyl oxalate (DEO) with the organic solvents ethanol, ethyl acetate (EA), tetrahydrofuran (THF), and toluene at temperatures ranging from 303.15 to 323.15 K and at atmospheric pressure. DEO is widely used in the pharmaceutical industry as an intermediate or reaction reagent for synthesizing active pharmaceutical ingredients. The measured thermophysical properties are important for pharmaceutical process design and development. A vibrating tube digital density meter and a capillary viscometer were used for density and viscosity measurements, respectively. According to the measurement data, the excess molar volumes (VE) and viscosity deviations () of the binary mixtures were calculated and satisfactorily correlated with the four-parameter Redlich–Kister equation. Ethanol or THF addition to DEO led to a positive deviation of VE, whereas EA or toluene addition to DEO led to a negative deviation. These results indicated the molecular packing of DEO with EA and toluene was more efficient than that with ethanol and THF. By contrast, thevalues of the four binary mixtures were negative, indicating that the viscosity was markedly lower than that of an ideal mixture.