What type of reaction occurs between an alkene and a halogen?

When an alkene reacts with a halogen, such as bromine or chlorine, the process that occurs is known as electrophilic addition. Alkenes are characterized by their carbon-carbon double bonds, which consist of a sigma bond and a pi bond. The pi bond is more reactive than the sigma bond, making the alkene a target for electrophiles.

In the first step of the electrophilic addition, the double bond acts as a nucleophile and attacks the halogen molecule. This interaction leads to the formation of a cyclic halonium ion intermediate. As the reaction continues, the halide ion generated from the halogen molecule attacks the intermediate, resulting in the formation of a vicinal dihalide, where two halogen atoms are added to adjacent carbons in the alkene.

This type of reaction is important in organic chemistry as it allows for the conversion of alkenes into more complex structures, often used in various synthetic processes. Electrophilic addition reactions highlight the reactivity of alkenes due to their unsaturation and the presence of electron-rich areas in the double bond.