ISSN:
0749-1581
Schlagwort(e):
31P
;
NMR
;
Aminoalkylphosphonic acids
;
PdII complexes
;
Enantiomeric purity determination
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
A convenient 31P NMR method for determining the enantiomeric excess of free 1-aminoalkylphosphonic acids is presented. It was found by NMR that the interaction of PdII ions with 1-aminophosphonate ligands (L) yields, in a non-diastereoselective manner, diastereoisomeric chelate pairs (PdL2) observable in alkaline D2O solutions. The chelate complexes give two peaks in the 31P NMR spectra; one corresponds to the chiral species e (both ligands are R or S enantiomers) and the second to the meso forms (R and S ligands). The shapes of these peaks and the differences in the chemical shifts for the species (Δδ) depend on the temperature and the resonance frequency, typical for a dynamic process. Under the experimental conditions used (273-293 K and 40.48 or 121.5 MHz) Δδ values in the range 0.03-0.18 ppm were obseved. The separation of the 31P NMR signals of eight of the ten investigated racemic acids allowed the determination of the enantiomeric purity. The measured enantiomeric excess of an enantiomerically enriched sample of 1-aminobenzylphosphonic acid (prepared by weighing) was in excellent agreement with the expected value.
Zusätzliches Material:
1 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/mrc.1260271004
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