Structural Elucidation of the Chlordene Isomer Constituents of Technical Chlordane

The technical chlordane constituents designated α-, β-, and γ-chlordene are isomers of chlordene (C₁₀H₆Cl₆). These isomers are formed via the rearrangement of chlordene by the action of Cl₂ or free-radical initiating agents, and they no longer possess the cyclodiene-type structure. Elucidation of these isomeric structures involved various chemical derivitization reactions. Oxidation with chromic oxide yielded ketones and epoxides while reduction with Zn-HOAc or CrCl₂ produced mono- and didechlorinated homologs. Photoisomers in which the two original ClC=CCl bonds had been cross-linked, resulted from their unsensitized uv irradiation. Spectral confirmation of structure was obtained by ¹H NMR and gas chromatography-mass spectrometry (GC-MS) studies. It is postulated that α-chlordene is 1,2,3,5,7,8-hexachloro-1,3a,4,5,6,6a-hexahydro-1,4-ethenopentalene (III) and β-chlordene is 2,3,3a,4,5,7-hexachloro-3a,6,7,7a-tetrahydro-1,6-methano-1H-indene (XIII), with γ-chlordene (XI) being the 2,3,3a,4,5,8-hexachloro isomer of β-chlordene.