Allyl Anion
Allyl Anion - Related Videos
01:18
π Molecular Orbitals of the Allyl Cation and Anion
0 Views •
2025
An allyl group is a three-carbon conjugated system where the sp³-hybridized allylic carbon is bonded to a CH=CH2 group via a single bond. Allyl anions can be obtained by treating propene with a strong base that can deprotonate methyl groups. Allyl cations are formed as intermediates during substitution reactions involving allylic halides. In both cases, the hybridization of the allylic carbon changes from sp3 to sp2, giving rise to a carbon chain with three sp2-hybridized carbons, each with an...
06:46
Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
0 Views •
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.
02:38
Anion Exchange Resin–Based Detection of Viruses from Bioaerosols
0 Views •
2026
Source: Schaeffer, J. W., Chandler, et al. Detection of Viruses from Bioaerosols Using Anion Exchange Resin. J. Vis. Exp. (2018).This video demonstrates the detection of viruses from bioaerosols using an anion exchange resin. A liquid impinger containing the resin is used to capture viruses from the air. The resin is collected and treated with a virus lysis buffer containing carrier RNA. The lysate is transferred to a microcentrifuge tube for viral RNA isolation, followed by qRT-PCR to amplify...
01:27
π Molecular Orbitals of the Allyl Radical
0 Views •
2025
Allyl radicals are three-carbon conjugated systems. They are readily formed as intermediates in halogenation reactions of alkenes involving the addition of halogen to the allylic carbon instead of the double bond. As seen in allyl cations and anions, each of the three sp2-hybridized carbon atoms in allyl radicals has an unhybridized p orbital. These orbitals combine to give three π molecular orbitals. The allyl systems have identical molecular orbitals but differ in the number of π electrons.
01:31
Radical Substitution: Allylic Chlorination
0 Views •
2023
Typically, when alkenes react with halogens at low temperatures, an addition reaction occurs. However, upon increasing the temperature or under reaction conditions that form radicals, providing a low but steady concentration of halogen radicals, allylic substitution reaction is favored. This is because allylic hydrogens are very reactive as the formed intermediate is resonance stabilized. For example, when propene is treated with chlorine in the gas phase at 400 °C, it undergoes allylic...
FAQs
Its stability comes from conjugation between the negatively charged carbon p orbital and the neighboring carbon-carbon pi bond. This overlap creates a continuous three-carbon electronic system rather than confining the charge to one atom. Because the charge is delocalized, the anion has distinctive reactivity that differs from a carbanion with no adjacent pi bond.
The delocalized charge is concentrated primarily at the two terminal carbons of the three-carbon framework. Both ends therefore represent chemically important reaction sites, while the central carbon connects the conjugated system. This distribution explains why reactions involving allylic species can produce connectivity at either terminus rather than at only the carbon initially bearing the charge.
An ambident nucleophile can form a new bond through more than one atom. In this case, delocalization makes either terminal carbon available for bond formation. The two possible sites are not independent isolated charges; they are connected through the same conjugated system. Consequently, the electronic structure provides a basis for regioselectivity in reactions of allylic intermediates.
Resonance creates two terminal positions that can participate in carbon-carbon bond formation, so the reaction outcome depends on which site reacts under the particular conditions. The key issue is not simply where the negative charge is drawn in one structure, but how the delocalized system interacts with the reacting partner. This helps interpret products formed from allylic species.
Allyl anion equivalents provide the reactivity of an allylic nucleophile without requiring the free anion to be handled as an isolated species. They are especially useful for constructing carbon-carbon bonds through allylic alkylation. In synthesis, this strategy translates the anion's delocalized, two-ended reactivity into a controlled method for assembling more complex carbon frameworks.
Enolates and organometallic reagents can display reaction behavior that is interpreted through allylic anion-like delocalization or related nucleophilic frameworks. Examining where their electron density can form a bond helps explain regioselectivity, meaning the preference for one bonding position over another. This connection makes allyl anion chemistry useful for understanding broader carbon-carbon bond-forming reactions in organic synthesis.