Axially chiral binaphthoic acid (BNA) was studied as a resolving agent for a stereoselective crystallization of 1-(4-chlorophenyl)ethylamine (CPEA). The diastereomeric pair of (R)-BNA/(S)-CPEA crystallizes in methylene chloride, on the other hand, the pair of (S)-BNA/(S)-CPEA crystallizes in acetone. The switch of the solubility of the diastereomeric pair is due to the imine formation with acetone. The very low solubility of the BNA/imine pair appears to be responsible for the fast and complete imine formation. The crystal structure of the BNA part in both crystals of the diastereomers maintains a same feature. Asymmetric chiral channels and pockets composed by intermolecular packing of BNA molecules appear in the crystal structures, and the robustness of them seem to contribute to the recognition of the chirality of CPEA with high selectivity.
Bibliographical noteFunding Information:
This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2013R1A1A2008959), and by the Technology Innovation Program (WPM-10037719). M.-J. Jun is grateful to the ReSEAT Program, Korea Institute of Science & Technology Information for the support. Haofei Huang acknowledges the National Natural Science Foundation of China (no. 21306107).
© 2016 Korean Chemical Society, Seoul & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Binaphthoic acid
- Chirality switching
- Stereoselective crystallization