Crystallization, Dehydration, and Phase Transformations of Diastereomeric Salts: L-Ephedrine and D-Tartaric Acid

摘要

A screening of crystallization conditions for the diastereomeric salts formed by L/D-tartaric acid and a common chiral resolving agent, L-ephedrinc, in water is reported. Eight different salts with 1:1 and 2:1 stoichiometrics were synthesized, identified, and characterized, including three previously reported LL-salts. All new LD-salts were investigated by differential scanning calorimetry, thermogravi-metric and elemental analysis, infrared spectroscopy, solid-state NMR, and powder XRD. 1:1 LD-tartrate is anhydrous and 2:1 LD-tartrate crystallizes as a mono-hydrate; its dehydration and phase transformations on heating were monitored in situ by variable-temperature XRD and hot-stage microscopy.KChiral resolution;; Crystallization;; Hydrates;; Pharmaceutical products;; Polymorphism