6(A),6(B)-BETA-CYCLODEXTRIN HEXASILOXANE COPOLYMERS - ENANTIOMERIC SEPARATIONS BY A BETA-CYCLODEXTRIN-CONTAINING ROTOXANE COPOLYMER

6(A),6(B)-Bis-O-[p-(allyloxy)phenyl]per-O-methyl-beta-cyclodextrin, prepared from beta-cyclodextrin (CD) by a five-step process, has two isomeric forms, Form A has the two p-(allyloxy)phenyl substituents directed away from the CD cavity, while form B is a rotoxane with one p-(allyloxy)phenyl group in the CD cavity. CD-hexasiloxane copolymers were prepared by treating each form with 1,1,3,3,5,5,7,7,9,9,11,11-dodecamethylhexasiloxane (with Si-H functions on each end) using a platinum catalyst. These copolymeric stationary phases were coated on fused silica capillary columns and found to separate enantiomeric solutes in gas chromatography (GC). The copolymer prepared from form A separated both enantiomeric hydrocarbons and polar solutes, Rotoxane copolymer prepared from form B separated only polar solutes. Since form B copolymer is a rotoxane with the benzene part of the copolymer in the cavity, these results show that an open CD cavity is necessary for interaction and enantiomeric resolution of nonpolar hydrocarbons; however, polar solutes interact effectively with the polar CD rim or exterior surface.