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Aldehyde structure. In organic chemistry, an aldehyde (/ ˈ æ l d ɪ h aɪ d /) is an organic compound containing a functional group with the structure R−CH=O. [1] The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl group.
The Norrish type I reaction is the photochemical cleavage or homolysis of aldehydes and ketones into two free radical intermediates (α-scission). The carbonyl group accepts a photon and is excited to a photochemical singlet state. Through intersystem crossing the triplet state can be obtained.
The Reformatsky reaction (sometimes transliterated as Reformatskii reaction) is an organic reaction which condenses aldehydes or ketones with α-halo esters using metallic zinc to form β-hydroxy-esters: [1] [2] The Reformatsky reaction. The organozinc reagent, also called a 'Reformatsky enolate', is prepared by treating an alpha-halo ester ...
An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration to give a conjugated enone.
Ketones are trigonal planar around the ketonic carbon, with C–C–O and C–C–C bond angles of approximately 120°. Ketones differ from aldehydes in that the carbonyl group (C=O) is bonded to two carbons within a carbon skeleton. In aldehydes, the carbonyl is bonded to one carbon and one hydrogen and are located at the ends of carbon chains.
Aldol reactions may proceed by two distinct mechanisms. Carbonyl compounds, such as aldehydes and ketones, can be converted to enols or enol ethers. These species, being nucleophilic at the α-carbon, can attack especially reactive protonated carbonyls such as protonated aldehydes. This is the 'enol mechanism'.
Aldehydes and to some extent even ketones, hydrate to geminal diols. The reaction is especially dominant for formaldehyde, which, in the presence of water, exists significantly as dihydroxymethane. Conceptually similar reactions include hydroamination and hydroalkoxylation, which involve adding amines and alcohols to alkenes.
The Dakin oxidation. The Dakin oxidation (or Dakin reaction) is an organic redox reaction in which an ortho- or para-hydroxylated phenyl aldehyde (2-hydroxybenzaldehyde or 4-hydroxybenzaldehyde) or ketone reacts with hydrogen peroxide (H 2 O 2) in base to form a benzenediol and a carboxylate.