Free-radical reactions of halogenated bridged polycyclic compounds. Part X. Addition of bromine and chlorine to hexachloronorbornadiene
The addition of bromine in carbon tetrachloride or acetic acid to hexachloronorbornadiene affords the products of endo-cis- and trans-addition of bromine to the unsubstituted double bond, and the rearrangement product 5-exo,-7-anti-dibromo-1,2,3,5-endo,6,6-hexachloronorborn-2-ene. With chlorine, in addition to the products of endo-cis- and trans-addition, two rearrangement products, 1,2,3,5,5,6,6,7-anti-octachloronorborn-2-ene and its 7-syn-epimer, are formed. The effect of changes in temperature, and of added free-radical catalysts and inhibitors, on the product ratios, has been examined to provide evidence for possible intermediates in these addition reactions. Sulphuryl chloride has been used to add, in a free-radical manner, the elements of chlorine to hexachloronorbornadiene. This affords the products of endo-cis- and trans-addition to the unsubstituted double bond together with the rearrangement product 1,2,3,5,5,6,6,7-anti-octachloronorborn-2-ene.