Alkene Addition
Alkene Addition - Related Videos
02:24
Introduction to Electrophilic Addition Reactions of Alkenes
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2023
The double bond in a simple, unconjugated alkene is a region of high electron density that can act as a weak base or a nucleophile. The filled π orbital (HOMO) of the double bond can interact with the empty LUMO of an electrophile. A bonding interaction occurs when the electrophile attacks between the two carbons; the electrophile then accepts a pair of electrons from the π bond and undergoes addition across the double bond, yielding a single product. Addition and elimination reactions can be...
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...
06:52
Ozonolysis of Alkenes
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2023
Source: Vy M. Dong and Zhiwei Chen, Department of Chemistry, University of California, Irvine, CA This experiment will demonstrate an example of an ozonolysis reaction to synthesize vanillin from isoeugenol (Figure 1). Ozonolysis of alkenes, an oxidation reaction between ozone and an alkene, is a common method to prepare aldehydes, ketones, and carboxylic acids. This experiment also demonstrates the use of an ozone generator and a low temperature (−78 °C) reaction. Figure 1. Diagram showing...
FAQs
The π bond contains electron density that can interact with an electrophile, making it the first point of chemical engagement. This interaction changes the original bonding arrangement and initiates formation of new bonds. The resulting pathway then continues through either a discrete intermediate or a coordinated transition state before the remaining reactant becomes bonded to the alkene-derived structure.
An electrophile or another reactive species first interacts with the electron-rich π bond, while a nucleophile or second reactant participates in the subsequent bonding step. Their sequence determines how the reaction progresses from initial activation to product formation. Consequently, the identities and reactivities of these participants help control which new functional groups appear in the final molecule.
Reagents and conditions determine which reactive pathway the alkene follows and therefore which groups become attached across the former double bond. Depending on those choices, the products may include alkyl halides, alcohols, alkanes, or other functionalized compounds. Selecting conditions is therefore central to directing the chemical outcome toward the desired type of molecular modification.
The reacting species do not all follow an identical bonding sequence. In some pathways, initial interaction produces an intermediate that undergoes a later reaction with a nucleophile or second reactant. In others, the bonding changes are represented by a coordinated transition state. This distinction describes the reaction mechanism and helps explain why different reagent systems can produce different outcomes.
Begin by identifying the alkene and its carbon–carbon double bond, then determine which electrophile, nucleophile, or second reactive species is present. Next, follow the proposed bonding sequence through its intermediate or coordinated transition state. Finally, identify the new σ bonds and classify the product, such as an alkyl halide, alcohol, alkane, or other functionalized compound.
The product class depends on the atoms or groups delivered across the alkene and on the selected reaction conditions. Supported outcomes include alkyl halides, alcohols, alkanes, and other functionalized products. This range makes the reaction family useful for changing an alkene-containing starting material into molecules with different chemical functions and synthetic potential.
Researchers choose this reaction family when they need to modify an alkene and introduce new chemical groups into a molecular framework. Such transformations support the construction of compounds relevant to pharmaceuticals, polymers, and materials chemistry. The approach is especially useful when the starting alkene provides a defined site for building additional σ bonds and increasing molecular functionality.
Its value extends from mechanism-based product formation to broader molecular design. By converting an alkene into a more functionalized structure, the process can help construct frameworks used in pharmaceutical research and materials development. In polymer chemistry, the same reaction family is part of the wider toolkit for preparing or modifying substances whose properties depend on molecular structure.