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Further Characterization of the Solid Forms of Iopanoic Acid and its Enantiomers
Author(s) -
Pitrè Davide,
Amici Marco De,
Colombo Mario,
Gualberto Gallo Gian,
Nebuloni Marino
Publication year - 1992
Publication title -
archiv der pharmazie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.468
H-Index - 61
eISSN - 1521-4184
pISSN - 0365-6233
DOI - 10.1002/ardp.19923250703
Subject(s) - enantiomer , eutectic system , chemistry , racemic mixture , crystallization , high performance liquid chromatography , chromatography , phase (matter) , acetic acid , analytical chemistry (journal) , stereochemistry , organic chemistry , alloy
The enantiomers of iopanoic acid were purified by crystallization and characterized by optical rotation, DSC, IR spectra, X‐ray powder diffraction, and chiral HPLC. (‐ R )‐enantiomer: [α] 20 D = −6.1°, mp. = 165.4°C; (+ S )‐enantiomer: [α] 20 D = + 6.2°, mp. = 165.6°C. The IR spectra and X‐ray patterns are fingerprints. Chiral HPLC (isocratic method, mobile phase: ethanol/ n ‐hexane, 2/98 with 0.5% acetic acid) gave a resolution = 0.98 and a 99.6% recovery. From X‐ray and thermal analyses the racemate Form I , mp. = 153.8°C, resulted to be a racemic compound. The binary phase diagram between the enantiomers and the racemic compound was constructed from the phase transition temp. obtained by DSC heating curves of appropriate mixtures. At a given enantiomer ratio (71/29) a eutectic compound, mp. = 144.7°C, is formed. In the range 88–100% a solid solution between the components is observed.