Chiral discrimination studies of (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid by high-performance liquid chromatography and NMR spectroscopy

✍ Scribed by Wonjae Lee; Eunjung Bang; Chae-Sun Baek; Weontae Lee

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 233 KB
• Volume: 42
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1353

✦ Synopsis

Abstract

Chiral discrimination studies using (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid (18‐C‐6‐TA) as a chiral selector were performed by high‐performance liquid chromatography (HPLC) and NMR spectroscopy. The enantiomers of alanine (Ala) or alanine methyl ester (Ala‐ME) were well separated on the chiral stationary phases (CSPs) derived from (+)‐18‐C‐6‐TA by HPLC. The chiral selector, (+)‐18‐C‐6‐TA, used in the CSP was also applied for the chiral discrimination of the Ala and Ala‐ME enantiomers, and it discriminated these enantiomers successfully by NMR spectroscopy. The chemical shift differences (Δ Δ δ) of the α‐proton of these enantiomers in the presence of an equimolecular solution of 18‐C‐6‐TA were observed to be 0.10 ppm for Ala in methanol‐d~4~ containing 10 mM H~2~SO~4~ and 0.11 ppm for Ala‐ME in methanol‐d~4~. The observed NMR results agreed with the chromatographic data on the (+)‐18‐C‐6‐TA‐derived CSP by HPLC in terms of both the elution order and solvents effects. Copyright © 2004 John Wiley & Sons, Ltd.