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

Bromohydrin Formation: Regiochemistry

 

Reactions of unsymmetrically substituted alkenes with bromine in water form bromohydrins in which the hydroxyl s located on the MORE substituted carbon atom:

 

FIGURE

 

This regiochemistry arises from the electrophilicity of the intermediate cyclic bromonium ion.

 

FIGURE