Limitations in determining enantiomeric excess of alcohols by 31P-NMR of the phosphonate derivatives
The use of diastereomeric alcohol dialkylphosphonate derivatives to determine the enantiomeric excesses via 31P-NMR signal ratios of anisochronous meso and threo isomers was successfully applied to secondary alcohols (Feringas method). Expansion of the methodology to primary alcohols possessing the hydroxyl groups thethered to the stereogenic centers by two or more methylene groups proved the method to be inefficent. The comparison between the coupled and decoupled spectra is important in order to identify the signals corresponding to the dialkylphosphonates. Nevertheless the methodology should be applied whenever the amount of the alcohol and its structure are not the limiting factors.
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| Main Authors: | , , , , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedade Brasileira de Química
1999
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50531999000400007 |
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| Summary: | The use of diastereomeric alcohol dialkylphosphonate derivatives to determine the enantiomeric excesses via 31P-NMR signal ratios of anisochronous meso and threo isomers was successfully applied to secondary alcohols (Feringas method). Expansion of the methodology to primary alcohols possessing the hydroxyl groups thethered to the stereogenic centers by two or more methylene groups proved the method to be inefficent. The comparison between the coupled and decoupled spectra is important in order to identify the signals corresponding to the dialkylphosphonates. Nevertheless the methodology should be applied whenever the amount of the alcohol and its structure are not the limiting factors. |
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