ISOMERIC AND ENANTIOMERIC COMPOSITION OF DIFFERENT COMMERCIAL TOXAPHENES AND OF CHLORINATION PRODUCTS OF (-CAMPHENE AND (-)-CAMPHENE())

The isomeric composition of commercial toxaphenes, including products of U.S and former East German origin, and the enantiomeric composition of several key components were investigated using achiral and chiral high-resolution gas chromatography (HRGC) in combination with mass spe ctrometry (MS). Achiral HRGC with electron-capture, negative ionizatio n (ECNI) MS was used for congener group analysis and chiral HRGC with electron ionization (EI) MS/MS for the isomer selective and enantiosel ective determination of some polychlorobornanes and polychlorobornenes . All products showed remarkably similar isomeric and enantiomeric com positions with some components present as almost racemic mixtures and others showing small but definite deviations from exact 1:1 enantiomer ic ratios. Laboratory-scale chlorination of (+)- and (-)-camphene led to similar mixtures of polychlorobornanes with approximate to 50% of t he enantiomeric excess retained. Chiroptical measurements showed a cha nge in the direction of rotation of camphenes upon chlorination: the n et rotation of the chlorination products of (-)-camphene was dextrorot atory, while those of (+)-camphene were levorotatory. The commercial t oxaphenes showed a small net rotation that is levorotatory.