Halogenation of Alkenes Halogenation of cycloalkenes Only trans-stereoisomer of dihalide product is formed Reaction occurs with anti stereochemistry -the two halogen atoms come from opposite faces of double- bond,one from top face and one form bottom face Br-Br Br Br Br Cyclopentene trans-1,2-Dibromo- cis-1,2-Dibromo- cyclopentane cyclopentane (sole product) (Not formed) Halogenation of cycloalkenes ▪ Only trans-stereoisomer of dihalide product is formed ▪ Reaction occurs with anti stereochemistry – the two halogen atoms come from opposite faces of double￾bond, one from top face and one form bottom face Halogenation of Alkenes