Journal of Chromatogruphy, 5 13 (1990) 3 15-320 Elsevier Science Publishers B.V., Amsterdam zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON CHROM . 22 472 Note Gas chromatographic separation of monoterpene hydrocarbon enantiomers on a-cyclodextrWb MIKAEL LINDSTROM and TORBJdRN NORIN Department of Organic Chemistry, Royal institute of Technology, S-100 44 Stockholm (Sweden) and JOHAN ROERAADE* Department of Analytical Chemistry, Royal Institute of Technology, S-100 44 Stockholm (Sweden) (First received September 25th, 1989; revised manuscript received March 28th, 1990) Monoterpene hydrocarbons are common natural products, and are the major constituents in turpentine and other essential oils’. Several monoterpenes are important mediators in the chemical communication between organisms and are essential in insect-plant interactions’. Most of these monoterpenes are chiral with the (+)- and (-)enantiomers often having different biological properties. The individual enantiomers of a compound such as a-pinene can be transformed to chiral auxiliaries, which are used in organic synthesis, e.g., hydroboration reactions3. Hence there is a need for rapid and accurate methods for the determination of the enantiomeric composition of monoterpene hydrocarbons. The classical polarimetric method and NMR techniques require large amounts of sample and are not suitable for complex mixtures or impure compounds. Chromatographic techniques are therefore more attractive [4-6]. A perpentyl-fl-cyclodextrin phase has been reported’ for gas chromatographic (GC) separations of some chiral olefins, including a-pinene and limonene. However, the enantioselectivity of such columns is limited, requiring high plate numbers, which lead to long analysis times. We have reported that the enantiomeric purity of monoterpene hydrocarbons can be determined by GC via transformation to carbamates that can be separated on a Chirasil-Val column’. Chiral olefins have also been converted to the corresponding diastereomeric ketal of (2R,3R)-2,3-butanediol that can be separated on standard GC columns’. However, these procedures are experimentally laborious and are therefore not suitable for routine analysis. In 1983, Koscielski et aL9 described a promising method for the enantiomeric separation of both a- and /3-pinenes using a-cyclodextrin in formamide as the stationary phase. Later, the same workers separated the enantiomers of pinanes and ’ Dedicated to Giinther Ohloff on the Occasion of his 65th Birthday. b Presented in part at the 1st International Symposium on the Separation of Chiral Molecules, Paris, 1988. 0021-9673/90/%03.50 0 1990 Elsevier Science Publishers B.V.