Crystallization in Polymorphic Systems:  The Solution-Mediated Transformation of β to α Glycine

The crystallization and subsequent polymorphic transformation from the β to the α form of glycine has been studied using optical microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy techniques. The crystal structure and morphology of β glycine have been determined, and the influence of solvent, solubility, and process scale on its solvent-mediated transformation to the α form was quantified. It is concluded that for the low solubility environments used in this study, the rate-determining step in the transformation process is the dissolution rate of the metastable β polymorph.