Solubility of Glycine Polymorphs and Recrystallization of β-Glycine

The solubilities of α-, β-, and γ-glycine in aqueous solutions containing methanol, ethanol, 2-propanol, or acetone were measured at 310 K. The solubility of all the polymorphs dropped rapidly as a function of the concentration of antisolvent. The solubility of the glycine polymorphs in water−antisolvent mixtures was, in decreasing order: methanol > ethanol > 2-propanol > acetone. The solubility of α-glycine was slightly higher than that of γ-glycine, but the solubility of β-glycine was significantly higher by up to 17 %. The induction time for the recrystallization of β- to α-glycine in those water−antisolvent mixtures was, in decreasing order: methanol > ethanol > acetone > 2-propanol. This signifies that the selection of an antisolvent for preparation of β-glycine can have an important effect on the product.