Toxaphene chemistry: Separation and characterisation of selected enantiomers of the Polychloropinene mixtures

The primary goal for the study presented here was the preparation and characterisation of enantiomeric pure chlorobornane standards (Toxaphene®). In this context, we partially modeled the procedure for Polychloropinene production in the former USSR. The initial reaction was ionic addition of hydrogen chloride to (1S)-α-pinene resulting predominantly in (1S)-2-endo-chlorobornane. Further photochlorination gave mixtures of chlorinated terpenes with different average content of Cl per molecule. The resulting mixtures were separated on a silica-gel column and a number of known hepta to decachlorobornanes were identified in fractions with the help of NMR and GC (using electron capture and mass spectrometric detection) - but in very unusual ratios as compared to the technical Toxaphene® mixture formerly produced by Hercules (USA). Also several previously unknown congeners were isolated or detected. Three of the isolated congeners were obtained in crystalline state and X-ray crystallography showed their enantiomeric purity.