Crystallization, Spectral, Crystallographical, and Thermoanalytical Studies of Succinobucol Polymorphism

Four different polymorphs, A, C, D, and E, of succinobucol were isolated and characterized by means of solid-state nuclear magnetic resonance spectroscopy, single crystal and powder X-ray diffraction, differential scanning calorimetry, thermogravimetry, and attenuated total reflection-infrared spectroscopy. From a number of experiments, the same polymorphs (C, D, and E) and an equilibrium phase mixture B consisting of polymorphs C and D were repeatedly gained using different solvents or their mixtures. Although polymorph A was obtained directly from recrystallization only on few occasions, polymorphs C, D, and E proved to be metastable kinetic polymorphs, which slowly transform to a thermodynamically more stable form A during long-term storage. The single-crystal structures of polymorph C and D were determined by X-ray single-crystal diffraction. © 2012 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 101:1794-1802, 2012