Page 227 - Chiral Separation Techniques

8.2 Chemistry 205

oped by IBC Advanced Technologies Inc. (IBC) of American Fork, Utah, USA for
use in enantiomeric separations, and a comparison of this technique with chromato-
graphic methods together with advantages and disadvantages of the methods; (iii) a
summary of the economic aspects of nonchromatographic separations together with
details of the operating aspects of the nonchromatographic separations system; (iv)
the use of the nonchromatographic system for the separation of valine enantiomers,
and (v) areas of potential industrial interest for nonchromatographic separations.

8.2 Chemistry

The similar stereochemistry of enantiomers makes their separation on a large scale
a challenging problem. We and others reasoned that separations of enantiomer guests
containing primary amines could be facilitated by designing host receptors whose
interaction with one of the enantiomers over the other was favored from a steric
standpoint [6]. This approach was successful, and has been used to show significant
differentiation by a given host between enantiomers in single phase homogeneous
solvents [6].

+
Fig. 8-1. Schematic representations of the interaction of the (R)NapEtNH enantiomer guest with a chi-
3
ral pyridine-18-crown-6 host (S,S)-1 and possible conformations of the (S,S)R P18C – (R)NapEt com-
2 6
plexes.