A MECHANISTIC APPROACH OF THE CHIRAL SEPARATION OF N-ARYLTHIAZOLIN-2-(THI)-ONE ATROPISOMERS ON CHIRALPAK AS AND CHIRALCEL OD-H

The separation of the title compounds was studied on two of the most u sed commercially available chiral stationary phases: amylose tris (S) ethylphenylcarbamate (CHIRALPAK AS) and cellulose tris (3,5-dimethylph enylcarbamate) (CHIRALCEL OD-H). Good resolutions are obtained on amyl ose phase whereas the cellulose phase showed low enantioselectivities for this type of compounds. The chiral recognition mechanism of the ti tle compounds was investigated by attempting to correlate the logarith ms of the capacity factors of each enantiomer on CSPs with the lipophi licity parameter. We obtained a linear correlation for the retention o n CHIRALPAK AS of the (+) enantiomer whereas an attractive effect :in respect to this correlation was pointed out for the retention of the ( -) enantiomer. In contrast, we obtained linear correlations between th e retention of both enantiomers on CHIRALCEL OD-H thus resulting in lo w separation factors. The implication of the hydrogen bonding abilitie s of the tested compounds is discussed.