Free-radical reactions of halogenated bridged polycyclic compounds. Part XVI. Addition of methanethiol and 1,1-dimethylethanethiol to 5-substituted 1,2,3,4,7,7-hexachloronorbornadienes

Abstract

The attack of alkylthio-radicals on a 5-substituted 1,2,3,4,7,7-hexachloronorbornadiene affords the 5-substituted 6-endo-alkylthio-1,2,3,4,7,7-hexachloronorborn-2-en-5-yl radical, which may undergo chain transfer from either the exo- or the endo-direction to afford a 5-endo(or 5-exo)-substituted 6-endo-alkylthio-1,2,3,4,7,7-hexachloronorborn-2-ene. Alternatively the radical can rearrange to the 4-substituted 7-syn-alkylthio-1,2,3,5,6,6-hexachloronorborn-2-en-5-yl radical, which on chain transfer affords the 4-substituted 7-syn-alkylthio-1,2,3,5-endo-6,6-hexachloronorborn-2-ene. Product proportions depend on the nature of the 5-substituent in the diene, and may be rationalised in terms of the possible structure of the first-formed radical, and of interactions between the 5-substitutent and the alkylthio-group in this radical. The major product from reaction of an alkanethiol with 5-chloromethyl-1,2,3,4,7,7-hexachloronorbornadiene is a 1,4,5,6,7,7-hexachloro-3-methylenenorborn-5-en-2-endo-yl alkyl sulphide.