CYCLODEXTRIN CARBAMATES AS NOVEL CHIRAL STATIONARY PHASES FOR CAPILLARY GAS-CHROMATOGRAPHY

The following carbamate derivatives of cyclodextrins (CDs) were prepar ed as novel chiral stationary phases for capillary gas chromatography: hexakis (2,6-di-O-pentyl)-alpha-cyclodextrin hexa(3-n-propyl, 3-isopr opyl, and 3-phenylcarbamate), heptakis-(2,6-di-O-pentyl)-beta-cyclodex trin hepta(3-n-propyl, 3-isopropyl, and 3-phenylcarbamate), and octaki s(2,6-di-O-pentyl)-gamma-cyclodextrin octa(3-n-propyl, 3-isopropyl, an d 3-phenylcarbamate). Metal capillary columns coated with these statio nary phases resolved many kinds of racemic mixture. In general, they w ere especially effective towards polar compounds such as free alcohols , amines, and epoxides. The types of sample which were effectively res olved depended on the cavity size of the CD: alpha-CD derivatives were specifically effective toward compounds having linear alkyl chains, a nd beta-CD derivatives toward compounds with phenyl groups. The result s indicate that chiral separation with the cyclodextrin carbamates dep ends on the formation of inclusion complexes and also on the hydrogen- bonding interactions between the samples and the CD carbamates.