Enantimeric separation of epxides by gas chromatography using derivatized alpha-cyclodextrins as stationary phases

Abstract

Enantiomeric separations of 42 aromatic epoxides and 6 aliphatic epoxides were studied by means of capillary gas chromatography using derivatized α-cyclodextrins: hexakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)cyclomaltohexaose (or ASiMe) and hexakis(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)cyclomaltohexaose (or ASiAc) as chiral stationary phases. The effects of substitution types, number and position of epoxides on retention and enantioselectivity have been investigated. The results showed that all epoxides were successfully separated with either ASiMe or ASiAc or both columns, except benzyl glycidyl ether (8) and 1,2-epoxydodecane (dodec). ASiMe column could enantioseparate 41 analytes while ASiAc column could resolve only 16 analytes. Aromatic epoxides were better separated on ASiMe column. Furthermore, the position and type of substituent on aromatic ring of styrene oxide played important roles on enantioseparation. Thermodynamic data were acquired to clarify the interaction strength between analyte and stationary phase as well as the enantioselectivity towards the selected groups of epoxides.