NEW CHIRAL POLYSILOXANE DERIVED FROM (R,R)-TARTRAMIDE FOR ENANTIOMER RESOLUTION BY CAPILLARY GAS-CHROMATOGRAPHY

The synthesis was conducted of a polysiloxane in which the (R,R)-tartramide derivative as a chiral selector was attached to the polysiloxane backbone via 11 methylene units. Capillary gas chromatography using this polysiloxane as a chiral stationary phase was found to be capable of recognizing the molecular chirality of broad categories of volatile enantiomers containing 1,2-diols, 1-methoxy-2-alkanols, dialkyl tartrates, methyloximes of 2-hydroxy ketones, N,N'-bis(perfluoroacyl)-1,2- and -1,3-diamines, N-alkylamides of 2- and 3-halo carboxylic acids, and N-alkylamides of 2- and 3-hydroxy carboxylic acids. The mode of complexation responsible for the observed enantioselection was ascribed to dual hydrogen bonding between the (R,R)-tartramide moiety of the polysiloxane and solute enantiomers to be resolved. Dual hydrogen bonding between (R,R)-tartramide and some enantiomers is discussed on the basis of the differences in H-1 NMR chemical shifts observed for the enantiomeric pair in a CDCl3 solution containing (R,R)-N,N'-diisopropyltartramide.