Final answer:
The reaction of halogens with alkenes in dichloromethane leads to halogenation, forming dihaloalkanes where the alkene double bond is substituted by halogen atoms, resulting in products like dibromoalkane or dichloroalkane.
Step-by-step explanation:
The reaction of halogens (Br₂, Cl₂) with an alkene in an inert solvent such as dichloromethane (CH₂Cl₂) typically results in a halogenation reaction where the alkene double bond is broken and a dihaloalkane is formed. This is known as the addition reaction, where each halogen atom adds across the carbon-carbon double bond. If we react bromine (Br₂) with an alkene, for example, the alkene will undergo a color change from brownish-red to colorless, indicating that the reaction has occurred and a dibromoalkane has been formed.
The reaction with chlorine (Cl₂) behaves similarly, resulting in a dichloroalkane. Alkanes can also react with halogens, but more controlled conditions such as ultraviolet light or high temperatures are needed. This process converts less reactive alkanes to more reactive haloalkanes, which have polar carbon-halogen bonds and are useful as intermediates in organic synthesis.