Preparative Chromatography - The Preparative Separation of the Enantiomers of Chlorokynurenine > Page 68

Enantiomers of a single substance are essentially chemically identical and only differ in the spatial arrangement of chemical groups or atoms around a single atom, referred to as the stereogenic center or the chiral center(s). Such differences impart very subtle physical chemical variations between the individual isomers and, thus, must be carefully exploited if a chromatographic separation of the individual enantiomers is to be achieved. A number of antibiotics have been shown to be very effective stationary phases for the separation of chiral mixtures. An example of one of these is Vancomycin the structure of which is depicted in figure 37. Vancomycin has three fused rings (shown as rings A, B and C in figure 37) and 18 chiral centers which endows it with the characteristic strong chiral selectivity exhibited by many antibiotics.


Figure 37. The Structure of Vancomycin