Which of the following best describes the reaction of alkenes with halogens?

The reaction of alkenes with halogens typically occurs without the need for any special reaction conditions, such as heat or a catalyst, making it a straightforward addition reaction. In this process, a halogen molecule (like Cl2 or Br2) adds across the carbon-carbon double bond of the alkene. The double bond is broken, leading to the formation of a cyclic halonium ion intermediate, followed by the addition of the halogen atoms to the alkene, resulting in the formation of a halogenated alkane.

This characteristic of proceeding without special conditions makes the reaction accessible under normal conditions, which is a key feature of halogen reactions with alkenes. Understanding this aspect helps explain why alkenes are reactive and engage in addition reactions so readily, showcasing their importance in organic synthesis.