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General structure of 1,2-, 1,3-, and 1,4-dicarbonyls. In organic chemistry, a dicarbonyl is a molecule containing two carbonyl (C=O) groups.Although this term could refer to any organic compound containing two carbonyl groups, it is used more specifically to describe molecules in which both carbonyls are in close enough proximity that their reactivity is changed, such as 1,2-, 1,3-, and 1,4 ...
A classic example for favoring the keto form can be seen in the equilibrium between vinyl alcohol and acetaldehyde (K = [enol]/[keto] ≈ 3 × 10 −7). In 1,3-diketones, such as acetylacetone (2,4-pentanedione), the enol form is more favored. The acid-catalyzed conversion of an enol to the keto form proceeds by proton transfer from O to carbon.
Dibenzoylmethane (DBM) is an organic compound with the formula (C 6 H 5 C(O)) 2 CH 2.DBM is the name for a 1,3-diketone, but the compound exists primarily as one of two equivalent enol tautomers. [2]
The DeMayo reaction is a photochemical reaction in which the enol of a 1,3-diketone reacts with an alkene (or another species with a C=C bond) and the resulting cyclobutane ring undergoes a retro-aldol reaction to yield a 1,5-diketone: [1] The net effect is to add the two carbon atoms in the C=C double bond between the two carbonyl groups of ...
Benzoylacetone is the organic compound with the nominal formula C 6 H 5 C(O)CH 2 C(O)CH 3. As a 1,3-dicarbonyl, it is a precursor to many heterocycles, such as pyrazoles. [1] It exists predominantly as the enol tautomer C 6 H 5 C(OH)=CHC(O)CH 3. [2] Its conjugate base (pK a =8.7) forms stable complexes with transition metals and lanthanides. [3]
Dibenzyl ketone, or 1,3-diphenylacetone, is an organic compound composed of two benzyl groups attached to a central carbonyl group. This results in the central carbonyl carbon atom being electrophilic and the two adjacent carbon atoms slightly nucleophilic.
The equilibrium constant tends to be high in nonpolar solvents; when K keto→enol is equal or greater than 1, the enol form is favoured. The keto form becomes more favourable in polar, hydrogen-bonding solvents, such as water. [7] The enol form is a vinylogous analogue of a carboxylic acid. [citation needed]
If the enol has an adjacent stereocenter, then the two stereocenters flanking the carbonyl in the product are naturally syn: [23] The underlying mechanistic reason depends on the enol isomer. For an E enolate, the stereoinduction is necessary to avoid 1,3-allylic strain, while a Z enolate instead seeks to avoid 1,3-diaxial interactions: [24]