Rozróżnianie molekuł a spektroskopia NMR cieczy

The high resolution NMR spectroscopy in liquids is a convenient tool for differentiating stereoisomers. Diastereomeric structures having different spatial distribution of electron density produce different magnetic environments for their nuclei and in consequence have, in general, different NMR spectra. The same concerns diastereotopic groups in a molecule. On the other hand, enantiomers or enantiotopic groups can be differentiated only when they are placed in a chiral environment. It can be accomplished by transforming enantiomers into their diastereomeric derivatives with the aid of chiral derivatising reagents, or by using chiral complexing or solvating agents. The most popular methods of practical realization of these approaches have been reviewed and illustrated with some examples. The spectroscopic differentiation of enantiomers provides a possibility of determining their absolute configurations.