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The binary phase diagrams of hydrogen halides salts of medetomidine (Med.HX, X:Br,I) and hydrogen oxalate salt of medetomidine (Med.Ox) were determined based on thermogravimetric/differential thermal analysis (TGA/DTA) and their crystal structure behavior was confirmed by comparison of the X-ray diffractometry and FT-IR spectroscopy of the racemate and pure enantiomer. All hydrogen halide salts presented racemic compound behavior. Heat of fusion of halides salt of (rac)-medetomidine decreased with ionic radius increase. Eutectic points for Med.HCl (previously reported), Med.HBr, and Med.HI rest were unchanged approximately. The solubility of different enantiomeric mixtures of Med.HBr and Med.HI were measured at 10, 20, and 30°C in 2-propanol showing a solubility increase with ionic radius. A binary phase diagram of Med.Ox shows a racemic conglomerate behavior. The solubility of enantiomeric mixtures of Med.Ox were measured at 10, 20, 30, and 40°C. The ternary phase diagram of Med.Ox in ethanol conforms to a conglomerate crystal forming system, favoring its enantiomeric purification by preferential crystallization.

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Many intermolecular forces and parameters affect the solubility of a compound in a solvent. Various thermodynamic models are presented to predict these parameters and determine solid liquid equilibrium data. By selecting suitable thermodynamic model for solubility modeling, calculation error is reduced and the results will be closer to the experimental data. Herein, the ability of two predictive and two correlative models in solubility modeling of chiral compounds is investigated. Thus, solubility of pure and racemic forms of chiral Ketamine, Mandelic acid and 3-Chloromandelic acid is evaluated using UNIQUAC and NRTL models. The solubility modeling of pure and racemic forms of Ketamine in Ethanol is also determined by UNIFAC and NRTL-SAC models. There are good agreement between experimental data and results of NRTL and UNIQUAC models. Predictive NRTL-SAC model shows smaller deviation than UNIFAC in solubility determination of pure and racemic form of Ketamine.