Halohydrin formation reaction

A halohydrin formation reaction is an organic chemical reaction where a halogen is added to an alkene in aqueous solution to form a halohydrin. The reaction is similar to the halogen addition reaction.

The basic chemical equation for this reaction is as follows:

C=C + X₂ in H₂O --> X-C-C-OH

(X represents a halogen, either Cl or Br).

The reaction occurs with anti addition, leaving the newly added X and OH groups trans to each other.

The reaction is a form of electrophilic addition.

In the first step, a halogen attacks the pi bond of the carbon-carbon double bond, forming a single bond to each of the two carbons. Then an H₂O molecule bumps into the slightly positively charged carbon atom that results from step one, bonding before the negative halogen atom left over can bond. The oxygen at this point has three bonds and a positive formal charge. Another water molecule happens by quickly enough to escort off the extra H ion, leaving the final product.