PREPARATIVE GAS-CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF METHYL 2-CHLOROPROPIONATE USING A CYCLODEXTRIN-BASED STATIONARY-PHASE

The enantiomers of methyl Z-chloropropionate, a volatile synthetic pre cursor, have been separated by preparative-scale gas chromatography us ing a 1 m x 22.5 mm I.D. column, packed with 20% (w/w) trichloroacetyl P-cyclodextrin-coated 60-80-mesh Chromosorb A. The preparative column was installed in a custom-designed preparative gas chromatograph and operated in the isothermal mode. An effluent-sampling interface valve, located between the exit of the preparative column and the fraction c ollector took 10- mu l samples of the effluent gas every 20 s and sent the samples onto a short, efficient analytical capillary column to pr ovide on-line enantiomeric analysis of the eluting bands. This near-re al-time knowledge of the enantiomer composition of the effluent gas le ads to aggressive, yet safe, fraction pooling schemes and permits the precise calculation of product purity, recovery and production rate. R esults for the preparative separation of racemic as well as enantiomer ically enriched (95% enantiomeric excess) feedstock are presented in t his paper.