Alpha Substituted Carbonyl
Alpha Substituted Carbonyl - Related Videos
01:26
Synthesis of α-Substituted Carbonyl Compounds: The Stork Enamine Reaction
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2025
α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon. However, enamines are neutral and less reactive than enolates, which bear a net negative charge. Consequently, enamines are effective Michael donors...
14:21
Nucleophilic Substitution
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2023
Source: Vy M. Dong and Daniel Kim, Department of Chemistry, University of California, Irvine, CA Nucleophilic substitution reactions are among the most fundamental topics covered in organic chemistry. A nucleophilic substitution reaction is one where a nucleophile (electron-rich Lewis base) replaces a leaving group from a carbon atom. SN1 (S = Substitution, N = Nucleophilic, 1 = first-order kinetics) SN2 (S = Substitution, N = Nucleophilic, 2 = second-order kinetics) This video will help to...
07:56
Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method
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Cited by 5 •
2017
Here we present a potentiometric titration technique for accurately quantifying carbonyl compounds in pyrolysis bio-oils.
10:14
Object Substitution Masking
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2023
Source: Laboratory of Jonathan Flombaum—Johns Hopkins University Visual masking is a term used by perceptual scientists to refer to a wide range of phenomena in which in an image is presented but not perceived by an observer because of the presentation of a second image. There are several different kinds of masking, many of them relatively intuitive and unsurprising. But one surprising and important type of masking is called Object Substitution Masking. It has been a focus of research in vision...
02:23
Alcohols from Carbonyl Compounds: Reduction
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2025
Reduction is a simple strategy to convert a carbonyl group to a hydroxyl group. The three major pathways to reduce carbonyls to alcohols are catalytic hydrogenation, hydride reduction, and borane reduction. Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
FAQs
Removing an alpha hydrogen can generate an enolate, and resonance with the carbonyl group stabilizes this species. That stabilization makes the alpha position a key site for subsequent reaction and helps explain why these compounds participate in carbon-carbon bond-forming processes. The carbonyl and adjacent carbon therefore function as a connected reactivity system.
An alpha substituent changes the environment around both the carbonyl and the neighboring carbon. It can alter alpha-hydrogen acidity, introduce steric effects, and influence enolate geometry. These changes affect which reaction pathway is favored, as well as the regioselectivity and stereochemical outcome observed in alkylation, condensation, or nucleophilic addition.
Enolate geometry provides a structural link between the arrangement of atoms and the products formed during reaction. Because an alpha substituent can influence that geometry, it may affect how the reactive intermediate approaches another component and which stereochemical outcome results. This makes geometric analysis important when predicting selectivity rather than considering carbonyl reactivity alone.
Begin by identifying the carbonyl type and examining the directly adjacent carbon for alpha hydrogens and substituents. Next, consider whether enolate formation is possible, how resonance stabilizes it, and how substitution may change acidity, steric effects, or geometry. This sequence helps connect molecular structure with likely alkylation, condensation, or addition behavior.
They are useful when a reaction requires a carbon-carbon bond to be constructed through control of the carbonyl-adjacent position. Their structural features support transformations such as alkylation and condensation, while the carbonyl also participates in nucleophilic addition. Chemists can therefore use these compounds as platforms for building more structurally complex molecules.
These compounds show how a small structural change near a carbonyl can influence several reaction properties at once. Alpha substitution can modify acidity, steric accessibility, enolate geometry, regioselectivity, and stereochemical outcome. Studying those relationships provides a chemistry context for understanding how molecular structure directs reaction pathways and determines the products formed.