The Chlorination of Olefins with Antimony(V) Chloride

Antimony(V) chloride was revealed to be a good reagent for the cis-chlorination of simple olefins in chlorinated hydrocarbon solvents, such as 1,2-dichloroethane, dichloromethane, chloroform, and carbon tetrachloride. The higher the reaction temperature or the solvent polarity was, the higher the selectivity for cis-chlorination became. From 1,3-butadiene, cis-1,4-dichloro-2-butene was formed together with the trans-1,4- and 1,2-dichloro isomers. In the cases of cyclopentene and norbornene, the trans-1,2-dichloride and other various dichlorides were obtained without any formation of the cis-1,2-isomer. Probable mechanisms for this chlorination are briefly discussed.