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Free-radical addition is an addition reaction in organic chemistry involving free radicals.〔L.G. Wade's Organic Chemistry 5th Ed. (p 319) – Mechanism supplements original.〕 The addition may occur between a radical and a non-radical, or between two radicals. The basic steps with examples of the free-radical addition (also known as radical chain mechanism) are: * Initiation by a radical initiator: A radical is created from a non-radical precursor. * Chain propagation: A radical reacts with a non-radical to produce a new radical species * Chain termination: Two radicals react with each other to create a non-radical species Free-radical reactions depend on a reagent having a (relatively) weak bond, allowing it to homolyse to form radicals (often with heat or light). Reagents without such a weak bond would likely proceed via a different mechanism. An example of an addition reaction involving aryl radicals is the Meerwein arylation. == Addition of mineral acid to an alkene == To illustrate, consider the alkoxy radical-catalyzed, anti-Markovnikov reaction of hydrogen bromide to an alkene. In this reaction, a catalytic amount of organic peroxide is needed to abstract the acidic proton from HBr and generate the bromine radical, however a full molar equivalent of alkene and acid is required for completion. Note that the radical will be on the more substituted carbon. Free-radical addition does not occur with the molecules HCl or HI. Both reactions are extremely endothermic and are not chemically favored. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Free-radical addition」の詳細全文を読む スポンサード リンク
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