Electron-deficient Alkenes
Electron-deficient Alkenes - Related Videos
06:46
Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
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Cited by 1 •
2017
The ruthenium-catalyzed olefination of electron-deficient alkenes with allyl acetate is described here. By using aminocarbonyl as a directing group, this external oxidant-free protocol has high efficiency and good stereo- and regioselectivity, opening a novel synthetic route to (Z,E)-butadiene skeletons.
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...
02:29
Nomenclature of Alkenes
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2023
The IUPAC naming system for alkenes replaces -an- with -en- in the corresponding parent alkanes. Accordingly, a simple alkene replaces the -ane suffix of the alkane with -ene. As per the IUPAC rules, the longest carbon chain containing the maximum number of double bonds is identified as the parent chain and is numbered such that the doubly bonded carbon atoms receive the lowest possible numbers. The location of the double bond is indicated by the number of its first carbon atom. In branched...
02:01
Isomerism in Alkenes
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2025
Alkenes like 1-butene and 2-butene exhibit constitutional isomerism, as they differ in the position of the double bond. Further, 2-butene exhibits stereoisomerism and exists as two distinct compounds differing in spatial arrangement. An isomer is called cis-2-butene when the methyl groups are on the same side of the double bond, and the other stereoisomer, in which methyl groups are on the opposite side of the double bond, is called trans-2-butene. The cis and trans stereoisomers are not...
02:46
Halogenation of Alkenes
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2025
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride. Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate. A...
FAQs
Conjugation and inductive effects act together to redistribute electron density across the alkene and its attached substituents. Conjugation transmits the influence of groups such as carbonyl, cyano, or nitro through the π system, while induction contributes through the molecular framework. This polarization helps explain the electrophilic character of the β-carbon and the resulting nucleophilic reactivity.
The nucleophile donates electron density into the polarized alkene, forming a new bond while changing the electron distribution of the original double bond. This addition can generate either a carbon–carbon or carbon–heteroatom connection, linking the alkene’s electronic structure directly to synthetic bond construction. The reaction outcome depends on how the polarized system accommodates the incoming electron density.
A Michael reaction is a conjugate nucleophilic addition in which a nucleophile reacts with an alkene activated by an electron-withdrawing group. For electron-deficient alkenes, this terminology emphasizes that conjugation influences the reaction pathway rather than treating the double bond as an isolated unit. It provides a useful framework for understanding reactivity, bond formation, and selectivity.
These electron-withdrawing groups help determine how electron density is distributed through conjugation and inductive effects. That distribution strengthens the electrophilic character of the β-carbon and can influence which site participates in nucleophilic addition. Consequently, substituent choice contributes to designing controlled transformations that favor formation of a particular new carbon–carbon or carbon–heteroatom bond.
A conceptual sequence begins by selecting an alkene bearing an electron-withdrawing group and a nucleophile capable of donating electron density. Under controlled conditions, the nucleophile adds to the polarized double bond, and the transformation is considered in terms of the bond it forms. This workflow connects substrate design, reaction control, and the intended synthetic outcome.
Formation of a new bond is not limited to one product class. Depending on the reacting partners, nucleophilic addition to polarized alkenes can create either carbon–carbon or carbon–heteroatom linkages. This flexibility makes the same electronic principle useful for constructing different molecular frameworks, while controlled conditions help align the alkene’s reactivity with the desired synthetic objective.
Their reaction behavior supports synthetic strategies associated with pharmaceuticals, natural products, polymers, and functional materials. In these settings, the value lies in using polarized alkene systems to form new bonds under controlled conditions. The same chemistry also provides a framework for studying how electron distribution, conjugation, and inductive effects influence alkene reactivity and selectivity.