Ei. Fedin et Va. Davankov, NMR INVESTIGATIONS OF THE ENANTIOMERIC EXCESS EFFECTS IN SOLUTIONS WITH WEAK INTERMOLECULAR ASSOCIATION, Chirality, 7(5), 1995, pp. 326-330
The main features of statistically controlled associate diasteromerism
(SCAD) in solution as measured by nuclear magnetic resonance (NMR) ar
e discussed. In an achiral solvent, (R)- and (S)-enantiomers can demon
strate distinct NMR signals, with the intensity ratio equal to the con
centration ratio, The previous theory of SCADA (anisochronism of nucle
ar magnetic moments caused by SCAD) is supplemented by treatment of en
antiomeric excess phenomena in relation with the hypothesis that a sam
ple consists totally of short-living diastereomeric dimers which are i
nvolved in fast (on the NMR time scale) exchange by enantiomers, Therm
odynamic parameters of SCAD as well as limits for enantioselectivity p
henomena are estimated. (C) 1995 Wiley-Liss, Inc.