Formation of Halohydrins (Addition of Hal₂ and H₂O to Alkenes)

Step 2: Nucleophilic Ring-opening

The molecule of water donates a lone pair of electrons to the electrophilic carbon atom of the cyclic bromonium ion.  A carbon-bromine bond is broken at the same time.  Examine the geometry for the attack of water on the electrophilic carbon atom in the 3D structure on the right.  What kind of reaction takes place at the electrophilic carbon atom?

Step 1 - Step 2 - Step 3

Key reaction: Nucleophilic attack of water on cyclic bromonium ion

Overall Reaction