Discrimination in Resolving Systems: Ephedrine-Mandelic Acid
Abstract
Resolution of mandelic acid with ephedrine in water and ethanol produces intermediate diastereomeric salts with greatly disparate solubilities and melting points. Single crystal x ray analysis of ephedrinium mandelates shows crystal structures which are isosteric, each crystallizing in the monoclinic system, space group C2. Protonated ephedrines occupy the same relative positions in the L- and M-salts, and mandelates are in the same general locations. Hydrogen bonds link alternating protonated ephedrine nitrogens and mandelate carboxylate oxygens in each salt forming columns of ions. The helical H bonded chain winds down the crystallographic two fold screw axis. Additional H bonds form between two-fold related mandelates in the L-salt. Mixed crystals, containing both mandelate isomers, (2R)- and (2S)-mandelates, are obtained from the resolving system partly depleted of the L-salt. A specimen with nearly equal amounts of the mandelates is also isosteric with the commensurate structures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 07, 1992
- Accession Number
- ADA246491
Entities
People
- Drake S. Eggleston
- Edward J. Valene
- Jeffrey D. Zubkowski
Organizations
- Jackson State University