Weilan Xue

Solubility and dissolution thermodynamics of hexaquoiron(III)tris(p-toluenesulfonate) in (ethanol+water) binary mixtures within 291.15–333.15 K

The solubility of hexaquoiron(III)tris(p-toluenesulfonate) [Fe(OTs)3·6H2O] in (ethanol+water) mixtures with a mole fraction of 0–0.327 ethanol was measured from 291.15 to 333.15 K by using a synthetic method. The experimental results show that the solubility of Fe(OTs)3·6H2O increases with an increase in temperature and an enrichment in ethanol content. The solubility data were correlated by the modified Apelblat equation, the Redlich-Kister (CNIBS/R-K) model, and the hybrid model, and the results showed that the three models agree well with experimental data. The thermodynamic properties of the dissolution process, including enthalpy, entropy, and Gibbs energy were estimated from the experimental data by the modified van’t Hoff equation, indicating that the process of the dissolution of Fe(OTs)3·6H2O is endothermic and spontaneous.

Mechanism and kinetics of esterification of adipic acid and ethylene glycol by tetrabutyl titanate catalyst

An eight-step mechanism of esterification reaction between adipic acid (AA) and ethylene glycol (EG) catalyzed by tetrabutyl titanate [Ti(OBu)4] was studied in detail. The kinetic data for the esterification reaction between AA and EG catalyzed by tetrabutyl titanate [Ti(OBu)4] were measured in the temperature range of 403 K-433 K. A second-order kinetic model was established, and the model parameters were obtained through an optimization procedure by minimizing the value differences between the simulated component concentrations in the reaction system with the experimental ones. The results demonstrate that the model is suitable for the esterification reaction between AA and EG catalyzed by tetrabutyl titanate [Ti(OBu)4]. Furthermore, the esterification reaction rate increases with the increase of reaction temperature, concentration of catalyst and the initial reactant ratio of EG to AA.

Response to “Comments on ‘Thermodynamic Models for Correlation of Solubility of Hexaquocobalt(II) Bis(p-toluenesulfonate) in Liquid Mixtures of Water and Ethanol from 288.15 to 333.15 K’”

The comments from Acree et al. [1], which are focused on ‘‘Thermodynamic Models for Correlation of Solubility of Hexaquocobalt(II) Bis(p-toluenesulfonate) in Liquid Mixtures of Water and Ethanol from 288.15 to 333.15 K’’ are appreciated. We have read it carefully and are particularly grateful to you for your hard work on this topic. In order to let other researchers and readers know better about our work, our explanations for the questions proposed by these comments are also given. In our recent paper [2] we reported the solubilities of hexaquocobalt(II) bis(p-toluenesulfonate) [Co(OTs)2 6H2O] in water and ethanol mixtures containing molar fractions of 0–0.342 ethanol from 288.15 to 333.15 K using a synthetic method. The experimental data were correlated by the modified Apelblat equation, the Combined Nearly Ideal Binary Solvent Redlich–Kister (CNIBS/R–K) model, and a hybrid model that was a combination of the Jouyban–Acree and modified Apelblat models. The parameters of the above models were listed in Tables 3–5 in [2]. Before the experiments, we did some pre-experiments that measured the solubility of Co(OTs)2 6H2O in ethanol and found the solubility of Co(OTs)2 6H2O increased little with increasing temperature. Therefore, we thought ethanol might not be a better choice as an antisolvent for crystallization of Co(OTs)2 6H2O in industry, and we decided to measure the solubilities of Co(OTs)2 6H2O in water rich binary solvents. Based on the experimental data, we found that the solubility tends to level out when the molar fraction of ethanol (x2) is in the range of 0.228–0.342. According to Liu et al. [3], some of the ethanol and water molecules in the mixture will form (water)2–ethanol clusters. Therefore, the addition of ethanol leads to the formation of more clusters. Combined with our research, we held the idea that these new clusters (formed by ethanol and water molecules, the molar fraction of ethanol is * 0.333, which is quite close to 0.342) were adverse to the increase of the