Radical Addition
Radical Addition - Related Videos
00:47
Radical Formation: Addition
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2023
Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical. Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an unpaired...
01:25
Radical Anti-Markovnikov Addition to Alkenes: Overview
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2023
The addition of hydrogen bromide to alkenes in the presence of hydroperoxides or peroxides proceeds via an anti-Markovnikov pathway and yields alkyl bromides. The observed regioselectivity can be explained based on the radical stability and steric effect. From the radical stability perspective, adding hydrogen bromide in the presence of peroxide directs the bromine radical at the less substituted carbon via a more stable tertiary radical intermediate. Similarly, in the steric framework, the...
01:32
Radical Anti-Markovnikov Addition to Alkenes: Thermodynamics
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2025
The anti-Markovnikov addition of hydrogen halides to an alkene is thermodynamically feasible only with HBr. The radical addition reaction with other hydrogen halides like HCl and HI is thermodynamically unfavorable. Thermodynamic factors The temperature influences the spontaneity of a reaction, which can be evaluated based on the change in the Gibbs free energy, ΔG. If the change in Gibbs free energy, ΔG, is negative, the reaction occurs spontaneously. As shown below, ΔG can be evaluated...
01:17
Radical Anti-Markovnikov Addition to Alkenes: Mechanism
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2025
The reaction of hydrogen bromide with alkenes in the presence of hydroperoxides or peroxides proceeds via anti-Markovnikov addition. The radical chain reaction comprises initiation, propagation, and termination steps. The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy radical...
14:22
Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development
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Cited by 9 •
2013
Radical-based biomimetic chemistry has been applied to building-up libraries necessary for biomarker development.
FAQs
Initiation creates radicals through heat, light, or a peroxide initiator. During propagation, a radical attacks a multiple bond and produces a new carbon-centered radical, allowing the sequence to continue through further additions. Termination occurs when radicals combine, removing reactive species from the chain. The balance among these stages influences whether addition proceeds efficiently or stops.
The carbon-centered radical formed after the initial attack is the key intermediate that connects one addition event to the next. Because it remains reactive, it can participate in further addition rather than ending the reaction immediately. This stepwise behavior allows chemists to build new carbon-carbon or carbon-heteroatom bonds from unsaturated starting materials.
Radical Addition proceeds through species containing unpaired electrons and carbon-centered radical intermediates, whereas ionic reactions follow a different electronic pathway. Its initiation can rely on heat, light, or peroxide conditions, so the transformation may operate under conditions that differ from ionic addition. This distinction helps chemists select a suitable mechanism for a planned organic conversion.
Analysis begins by identifying how radicals are generated, whether by heat, light, or a peroxide initiator. Next, follow attack at the alkene or alkyne multiple bond and formation of the carbon-centered radical. Finally, determine whether that intermediate propagates through additional addition or is removed by radical combination. This sequence clarifies the reaction pathway and outcome.
Chemists use this approach when they need to functionalize unsaturated molecules or create new carbon-carbon and carbon-heteroatom bonds. Its stepwise radical pathway can provide a synthetic option distinct from ionic reactions, especially when different reaction conditions are desirable. The resulting transformations support broader organic synthesis by converting alkene or alkyne functionality into more elaborated structures.
In polymerization, repeated radical additions can connect unsaturated units as the reactive sequence propagates. In molecular functionalization, addition across an alkene or alkyne introduces a new bond and changes the structure of the starting molecule. These applications make the process relevant both to chain-building chemistry and to the targeted modification of unsaturated compounds.