Thermodynamic equilibrium of hydroxyacetic acid in pure and binary solvent systems

Abstract

The solubility of hydroxyacetic acid in five pure organic solvents and two binary solvent mixtures were experimentally measured from 273.15 K to 313.15 K at atmospheric pressure (p=0.1 MPa) by using a dynamic method. The order of solubility in pure organic solvents is ethanol > isopropanol > n-butanol > acetonitrile > ethyl acetate within the investigated temperature range, except for temperature lower than 278 K where the solubility of HA in ethyl acetate is slightly larger than that in acetonitrile. Furthermore, the solubility data in pure solvents were correlated with the modified Apelblat model, NRTL model, and Wilson model and that in the binary solvents mixtures were fitted to the CNIBS/R-K model and Jouyban-Acree model. Finally, the mixing thermodynamic properties of hydroxyacetic acid in pure and binary solvent systems were calculated and discussed.

Commentary on “thermodynamic equilibrium of hydroxyacetic acid in pure and binary solvent systems”

“…Readers should exercise caution in using the curve-fit equation coefficients in Table 1. The equation coefficients that I obtained for the binary (ethanol + ethyl acetate) solvent system are significantly different than the values that Huang and coworkers report in Table 6 of their published paper [1]. As a quick check of my regression analysis, I substitute the numerical values given in Table 1 into Eqn.…”

“…One further comment is provided regarding the curve-fit equation coefficients given in the published paper by Huang and coworkers [1]. The curve-fit equation coefficients for the expression based on the Combined Apelblat-Jouyban-Acree model for the binary (acetone + ethanol) will likely have limited predictive ability as the experimental data used in determining the numerical values did not include solubility measurements in the acetone-rich concentration region.…”

“…In a recent paper appearing in This Journal Huang and coworkers [1] reported the solubility of hydroxyacetic acid in five neat organic mono-solvents, in binary (ethanol + ethyl acetate) and binary (acetone + ethanol) solvent mixtures in the temperature from 273.15 K to 313.15 K. The solubility was determined with a synthetic method that involved incremental solute addition until no more solute dissolved. Solute dissolution was followed with a laser monitoring method.…”

“…of the Huang et al paper[1].Errors can occur in curve-fitting experimental solubility data in accordance to specific mathematical equations and representations. In the case of the simplified version of the Combined NIBS/Redlick-Kister equation it is possible to check for errors simply by looking at the derived curve-fit equation coefficients.…”

Comment on “Measurement and Correlation of the Solubility of Maltitol in Different Pure Solvents, Methanol–Water Mixtures, and Ethanol–Water Mixtures”

“…The models are commonly used in the chemical and pharmaceutical industries. In the past two years there have been several incorrect applications ,− of the models that have led to calculated mole fraction solubilities that have exceeded unity in one or both of the monosolvents used to prepare the binary solvent mixture. Several of the incorrect applications ,, have involved solubility studies in which the authors performed experimental measurements in a very narrow range of binary solvent composition.…”