Ind. Eng. Chem. Res. 2008, 47, 8953–8956
8953
Measurement and Correlation of Solubility of Diphenyl Carbonate in Alkanols Dongwei Wei* and Yanhong Pei Tianjin Research and DeVelopment Center for Petrochemical Technology, Tianjin UniVersity, Tianjin 300072, People’s Republic of China
In an equilibrium vessel, the solubility of diphenyl carbonate (DPC) in alkanols was measured in the temperature range of 283-338 K, using a method in which an excess amount of solute was equilibrated with the alkanol solution. The liquid concentrations of the investigated DPC in the saturated solution were analyzed by spectrophotometry. The solubility data have been correlated as functions of the temperature. Activity coefficients for DPC have been calculated by means of the Wilson, NRTL, and UNIQUAC equations and, with them, were correlated solubility data that were compared with the experimental data. The best correlation of the solubility data has been obtained by the Wilson equation, by which the average root-mean-square deviation of temperature for the seven systems is 1.72 K. Introduction The chemical structure of diphenyl carbonate (DPC) (C13H10O3, CAS Registry No. 102-09-0) involved in this study is shown in Figure 1. DPC, which commonly appears as white flakes or crystalline powder, is an important chemical intermediate; it has been used extensively for the production of many organic and polymer materials, and it is particularly valuable for the synthesis of polycarbonate, because the use of highly toxic phosgene can be avoided.1,2 DPC quality directly impacts the downstream polycarbonate quality, so high-quality DPC is critical for polycarbonate optical media applications. The purification of DPC, according to the patent, may be performed using crystallization processes.3,4 To determine the proper solvent and design, an optimized crystallization process is necessary, to know its solubility in different solvents. In this paper, the solubility of DPC in methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and 2-methyl-1-propanol was measured in the temperature range of 283-338 K via a static analytical method. Experimental Section Materials. The chemicals of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and 2-methyl-1-propanol were supplied by Tianjin Kewei Chemical Reagent Co.; all were analytical research grade with a purity of >99.5%. All of the aforementioned solvents were refluxed over freshly activated CaO for 2 h and then fractionally distilled. Liquids were stored over freshly activated molecular sieves of type 4A. Analysis, using the Karl Fischer technique, showed that the water content in each of the solvents was
