Lisäysradikaalikovettuminen

Lisäysradikaali, often translated as "addition radical" or "radical addition," refers to a chemical reaction where a radical species adds across a double or triple bond. This process typically involves the breaking of a pi bond in the unsaturated molecule and the formation of a new sigma bond with the radical. The outcome is the generation of a new radical intermediate, which can then participate in further reactions, such as hydrogen abstraction or another addition.

The mechanism of addition radical reactions generally follows a chain process. Initiation involves the formation of a radical species, often through homolytic cleavage of a weak bond, for example, by heat or light, or by the action of an initiator. Propagation then involves the addition of the initial radical to the unsaturated substrate, creating a new radical. This new radical can then react with another molecule of the unsaturated substrate or with a different reagent in the system. Termination occurs when two radical species combine, ending the chain.

Common examples of addition radical reactions include the polymerization of alkenes, where monomers add to growing radical chains, and the halogenation of alkanes, where a halogen radical adds to an alkane. These reactions are important in organic synthesis and industrial processes, enabling the formation of various carbon-carbon and carbon-heteroatom bonds. Control over regioselectivity and stereoselectivity can be achieved by carefully selecting the reactants, initiators, and reaction conditions.