What reaction do alkenes undergo in the presence of halogens?

Alkenes undergo an addition reaction in the presence of halogens. This type of reaction involves the breaking of the double bond between the carbon atoms in the alkene, allowing two halogen atoms (such as chlorine, bromine, or iodine) to bond with the carbon atoms.

The double bond is a region of high electron density, which is reactive toward electrophiles like halogens. When a halogen molecule interacts with an alkene, the double bond facilitates the formation of a cyclic halonium ion intermediate. This intermediate leads to the subsequent addition of the halogen across the double bond, converting the alkene into a dihaloalkane.

This addition reaction is significant in organic chemistry because it illustrates how alkenes can be transformed into more saturated compounds through the addition of halogen atoms, altering their chemical properties and potentially enhancing their utility in various applications, such as the synthesis of pharmaceuticals and other organic compounds.