2,3-Di-O-methoxymethyl-6-O-tert-butyldimethylsilyl-β-cyclodextrin, a useful stationary phase for gas chromatographic separation of enantiomers

Heptakis(2,3-di-O-methoxymethyl-6-O-tert-butyldimethylsilyl) -β-cyclodextrin (2,3-MOM-6-TBDMS-β-CD), synthesized by using methoxymethylchloride (MOM-Cl) as derivatization reagent, was used for capillary gas chromatographic separation of enantiomers. The new chiral stationary phase proved to be suitable for the enantiodifferentiation of volatiles from various chemical classes. Compared to the corresponding γ-CD derivative (2,3-MOM-6-TBDMS-γ-CD), the spectrum of compounds for which enantiomers could be separated was more limited and the enantioseparation achieved was generally less pronounced. Unusually high separation factors were observed for 2-alkyl esters of short chain acids (C₂-C₆). Phenomena underlying the enantioseparation of 2-pentyl acetate (α: 4.31; 35°C) were investigated by determining thermodynamic parameters. Data show that only one enantiomer is retained significantly on the chiral stationary phase whereas the other one behaves like the hydrocarbons used as references.