CHROMATOGRAPHIC BEHAVIOR OF DIASTEREOMERS .4. PATTERNS OF ADSORPTION OF SOME RELATED ACYCLIC AND CYCLIC DIASTEREOMERS IN THIN-LAYER CHROMATOGRAPHY ON SILICA-GEL

For diastereomers of the types {A figure is presented}RM values on silica gel are investigated as a function of the mole fraction of the more polar solvent in binary solvent systems, according to Soczewiński's method. The correlation between RF and pKa is discussed, and thin-layer chromatographic comparison between acyclic and cyclic compounds is made. The data are consistent with two-point adsorption by the X and COOCH3 groups for the compounds where X is NCH3 or O and with one-point adsorption by X, where it is the NH group, via definite conformations. Thus, the semi-empirical postulates, made earlier on the basis of Snyder's theory, about the relative order of such diastereomers in thin-layer chromatography on silica gel, are both confirmed and specified. © 1979.