title: Anion effect on the binary and ternary phase diagrams of chiral medetomidine salts and conglomerate crystal formation.
abstract: 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.
authors.affiliation: Department of Chemistry, Shahid Beheshti University, Evin, Tehran, Iran.
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Choobdari
authors.forename: Hossein
authors.initials: H
authors.lastname: Fakhraian
authors.forename: Mohammad Hassan
authors.initials: MH
authors.lastname: Peyrovi
mesh_terms: D003460:Crystallization; D006219:Halogens / Q000737:chemistry; D020926:Medetomidine / Q000737:chemistry*; D010070:Oxalates / Q000737:chemistry; D012492:Salts / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D006219:Halogens; D010070:Oxalates; D012492:Salts; D020926:Medetomidine
keywords: X-ray diffractometry; chiral resolution; conglomerate; differential thermal analysis; enantiomer; medetomidine; phase diagram; preferential crystallization; racemic compound; thermogravimetric analysis