Ultraviolet Light Induced Dechlorination of Vicinal Polychlorocyclohexanes with Triethylamine

Article abstract of DOI:10.1021/jo00160a005

Photochemical dechlorination of trans- and cis-1,2-dichlorocyclohexanes (t-and c-DCC) in the presence of triethylamine (TEA) results in predominant dechlorination to form cyclohexene, where higher reactivity of the trans isomer over that of the cis (Φ_t-DCC/Φ_c-DCC = 4.8) is observed.Four stereoisomers of 1,2,3,4,5,6-hexachlorocyclohexanes, i.e., benzene hexaclorides (BHCs), were similarly dechlorinated to give their stereoselective benzene tetrachlorides (BTC), which mainly lose two adjacent chlorine atoms with a trans configuration to each other among the six chlorines available in BHC.Quantum efficiencies for the dechlorination of the four isomers α-, β-, γ-, and δ-BHC are 0.072, 0.060, 0.19, and 0,11, respectively, which correlate with their reduction potentials, implying that the reaction may be initiated by an electron transfer from TEA to BHC.