Solubility measurement and correlation of 2-chlorothioxanthone (CTX) in twelve mono organic solvents

Abstract

• Solubility of 2-chlorothioxanthone in twelve pure solvents was determined. • Solubility was correlated by Apelblat, λh , Wilson and NRTL model. • Thermodynamic properties of mixing process were also discussed. 2-Chlorothioxanthone (CTX) is one of the most widely used commercial photoinitiators for pharmaceutical preparations as well as for preparations of synthetic resins. The solubility of CTX in twelve pure organic solvents was measured using the gravimetric method from 287.55 to 335.95 K at normal pressure. The results shows that the solubility of CTX in all the solvents increases as temperature rising. The melting point and fusion enthalpy of CTX were measured with differential scanning calorimeter. The experimental solubility data were correlated with four thermodynamic models, including modified Apelblat equation, λh equation, Wilson equation and NRTL equation. The best correlation results were found with modified Apelblat equation and NRTL equation. The mixing thermodynamic functions (Gibbs free energy, enthalpy and entropy) were calculated based on the Wilson equation. The results showed that the entire mixing process is spontaneous.