1 H NMR Spectral Simplification with Achiral and Chiral Lanthanide Shift Reagents. Clenbuterol. Method for Direct Optical Purity Determination |
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| Authors: | Rolf Martin Robert Rothchild |
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| Institution: | 1. West Virginia State College, Department of Chemistry Institute , WV, 25112;2. The City University of New York John Jay College of Criminal Justice, Department of Science Toxicology Research and Training Center , 445 West 59th Street, New York, NY, 10019-1199 |
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| Abstract: | The 60 MHz 1H NMR spectra of clenbuterol, 1, have been studied in CDCl3 solution with the achiral shift reagent, tris (6,6,7,7,8,8,8-hepta-fluoro-2,2-dimethyl-3,5-octanedionato)europium (III), 2, and the chiral reagent tris3-(heptafluoropropylhydroxyn1ethyl-ene)-(+)-canphorato]europiunr(III), 3. Use of 3 resulted in observable enantiomeric shift differences, ΔΔσ, for the t-butyl, NH2 benzylic CH and the aryl proton signals. Values of ΔΔσ as high as 135.1 Hz (2.25 ppm) and 86.5 Hz (1.44 ppn) were seen for the methine and aryl protons, respectively, with a solution 0.1035 molal in 1 and a 1:3 molar ratio of 0.551. The aryl resonance is especially well suited for direct optical purity determinations of 1. |
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| Keywords: | Clenbuterol Lanthanide NMR Shift Reagents Optical Purity Enantiomers Chiral Conformation Europium |
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