Anti Markovnikov
Anti Markovnikov - Related Videos
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...
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...
02:20
Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
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2026
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others. The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
13:21
Antibody Generation: Producing Monoclonal Antibodies Using Hybridomas
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2023
Source: Frances V. Sjaastad1,2, Whitney Swanson2,3, and Thomas S. Griffith1,2,3,4 1 Microbiology, Immunology, and Cancer Biology Graduate Program, University of Minnesota, Minneapolis, MN 55455 2 Center for Immunology, University of Minnesota, Minneapolis, MN 55455 3 Department of Urology, University of Minnesota, Minneapolis, MN 55455 4 Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455 Polyclonal antibodies are defined as a collection of antibodies directed against...
FAQs
Peroxides promote a radical chain pathway for adding HBr to an unsymmetrical alkene. In this mechanism, the reaction proceeds through radicals rather than the concerted transition state associated with hydroboration. The chain process produces the complementary regiochemical result, allowing the bromine-derived functionality to appear at the less substituted position. This is useful when that specific brominated product is required.
Hydroboration places boron at the less substituted carbon because its concerted, sterically influenced transition state favors that arrangement. Oxidation then converts the carbon-boron placement into an alcohol at the corresponding position. This two-stage sequence links regioselective alkene addition to alcohol synthesis and provides a mechanistic alternative to peroxide-promoted HBr addition.
Although both approaches can produce complementary regiochemistry, they do so through different mechanistic logic. Peroxide-promoted HBr addition uses a radical chain, whereas hydroboration proceeds through a concerted transition state followed by oxidation. Recognizing this distinction helps chemists choose between an HBr-derived product and an alcohol while explaining how different mechanisms can produce the desired orientation.
Steric influence guides the concerted hydroboration transition state toward placement of boron at the less substituted carbon of the alkene. That orientation is important because oxidation preserves the carbon framework established during hydroboration while converting the boron-containing position into an alcohol. Consequently, steric control becomes a key source of regioselectivity in the overall sequence.
The sequence begins with hydroboration of the unsymmetrical alkene, which establishes the position of boron through a concerted, sterically influenced transition state. An oxidation step follows, converting the boron-substituted position into an alcohol. This workflow transforms the regioselective addition intermediate into an isolable oxygen-containing product and is distinct from direct HBr addition promoted by peroxides.
A chemist would choose this approach when the synthesis requires the complementary regioisomer rather than the product from the usual Markovnikov pattern. The choice can provide either an HBr-derived product through peroxide-promoted radical addition or an alcohol through hydroboration and oxidation. Such control is valuable for planning the position of functional groups in an organic molecule.
These reactions provide control over where new carbon-heteroatom bonds form during alkene transformations. Depending on the pathway, the result can be an HBr-derived product or an alcohol with the complementary regiochemical arrangement. This capability expands access to regioisomers and supports synthetic planning when the position of a functional group influences the usefulness of the final organic product.