OXAZEPINES AND THIAZEPINES .28. OPLC STUDY OF RETENTION OF 2,3-DIHYDRO-1,5-BENZOTHIAZEPINES ON LAYERS IMPREGNATED WITH TRICAPRYLMETHYLAMMONIUM CHLORIDE

The retention behaviour of various 2,3-dihydro-1,5-benzothiazepines was investigated by means of overpressured layer chromatography on silica gel and on alumina layers impregnated with tricapryl-methylammonium chloride (TCMA), with eluents containing methanol and water, but not TCMA. The retention of benzothiazepines, similarly to that of compounds with different chemical structures studied earlier, increased with increasing TCMA concentration on the layer, and decreased with increasing methanol content of the eluent. The interactions between the compounds and the capryl groups of the TCMA adsorbed on the layer are basically hydrophobic; for compounds which have strong acidic character ion-pairing may occur in the stationary phase. The type, number and positions of the benzothiazepine substituents can change the extent of the retention-increasing effect of TCMA. This is explained in detail. Impregnation of the silica gel layers with TCMA improved the resolution of the compounds.