α,β-unsaturated Aldehyde or α,β-unsaturated Ketone
Conditions
Temperature
+Δ, ~100°C[a]
Catalyst
−OH or H+
Identifiers
Organic Chemistry Portal
aldol-condensation
RSC ontology ID
RXNO:0000017
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.
The overall reaction equation is as follows (where the Rs can be H)
Aldol condensations are important in organic synthesis and biochemistry as ways to form carbon–carbon bonds.[2][3][4][5]
In its usual form, it involves the nucleophilic addition of a ketone enolate to an aldehyde to form a β-hydroxy ketone, or aldol (aldehyde + alcohol), a structural unit found in many naturally occurring molecules and pharmaceuticals.[6][7][8]
The Aldol reaction
The term aldol condensation is also commonly used, especially in biochemistry, to refer to just the first (addition) stage of the process—the aldol reaction itself—as catalyzed by aldolases. However, the first step is formally an addition reaction rather than a condensation reaction because it does not involve the loss of a small molecule.
^Klein, David R. (December 22, 2020). Organic chemistry (4th ed.). Hoboken, NJ: Wiley. p. 1014. ISBN 978-1-119-65959-4. OCLC 1201694230.
^Smith, M. B.; March, J. (2001). Advanced Organic Chemistry (5th ed.). New York: Wiley Interscience. pp. 1218–1223. ISBN 0-471-58589-0.
^Carey, Francis A.; Sundberg, Richard J. (1993). Advanced Organic Chemistry Part B Reactions and Synthesis (3rd ed.). New York, NY: Plenum. pp. 55. ISBN 0-306-43440-7.
^Wade, L. G. (2005). Organic Chemistry (6th ed.). Upper Saddle River, NJ: Prentice Hall. pp. 1056–1066. ISBN 0-13-236731-9.
^Mahrwald, R. (2004). Modern Aldol Reactions. Vol. 1, 2. Weinheim, Germany: Wiley-VCH. pp. 1218–1223. ISBN 3-527-30714-1.
^Heathcock, C. H. (1991). Additions to C-X π-Bonds, Part 2. Comprehensive Organic Synthesis. Selectivity, Strategy and Efficiency in Modern Organic Chemistry. Vol. 2. Oxford: Pergamon. pp. 133–179. ISBN 0-08-040593-2.
^Mukaiyama T. (1982). "The Directed Aldol Reaction". Organic Reactions. 28: 203–331. doi:10.1002/0471264180.or028.03. ISBN 0471264180.
^Paterson, I. (1988). "New Asymmetric Aldol Methodology Using Boron Enolates". Chemistry and Industry. 12. London: Paterson Group: 390–394.
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and 24 Related for: Aldol condensation information
An aldolcondensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde...
family of aldol reactions and similar techniques analyze a whole family of carbonyl α-substitution reactions, as well as the diketone condensations. When...
Many variations of condensation reactions exist. Common examples include the aldolcondensation and the Knoevenagel condensation, which both form water...
allows for a crossed aldol reaction between an aldehyde and a ketone (>C=O), or a different aldehyde without self-condensation of the aldehyde. For this...
chemist Emil Knoevenagel. It is a modification of the aldolcondensation. A Knoevenagel condensation is a nucleophilic addition of an active hydrogen compound...
β-hydroxyketone. In an aldolcondensation, water is subsequently eliminated and an α,β-unsaturated carbonyl is formed. The aldol cleavage or Retro-aldol reaction is...
the new ring. The final step is a dehydration, as seen following an aldolcondensation. It was discovered by the German chemist Hans von Pechmann . To synthesize...
stereoselective syntheses in the active area of asymmetric synthesis. Aldols may also undergo a condensation reaction in which the hydroxy group is replaced by a pi...
ester in the last step. Aldolcondensation Stobbe condensation Fatty acid synthesis Polyketide synthase Dieckmann condensation Carey, F. A. (2006). Organic...
Stobbe condensation is also illustrated by the synthesis of the drug tametraline. Aldolcondensation Polyketide synthase Dieckmann condensation Claisen...
β-unsaturated aromatic acid or α-substituted β-aryl acrylic acid by the aldolcondensation of an aromatic aldehyde and an acid anhydride, in the presence of...
ketone in a cyclohexane ring by a Michael addition followed by an aldolcondensation. This procedure is one of the key methods to form fused ring systems...
colorless, volatile liquid with a honey-like odor. It is prepared by the aldolcondensation of acetone to give diacetone alcohol, which readily dehydrates to...
nucleophilic. For this reason, dibenzyl ketone is frequently used in an aldolcondensation reaction with benzil (a dicarbonyl) and base to create tetraphenylcyclopentadienone...
metabolites. Octocrylene can convert to benzophenone through a retro-aldolcondensation. The reaction occurs slowly over time, yielding significant concentration...
used primarily as a source of the "CH3C+H(OH)" synthon in aldol reactions and related condensation reactions. Grignard reagents and organolithium compounds...
triflate is used in such reactions as aldol reactions and Diels–Alder reactions. An example is the Mukaiyama aldol addition reaction between benzaldehyde...
point the opposite way from the second and fourth. It is made by aldolcondensation of D- and L-glyceraldehyde. L-Idose is a C-5 epimer of D-glucose....
[−O−C(CH3)2−]n. The other type could be obtained through repeated aldolcondensation, with one molecule of water removed at each step, yielding a poly(methylacetylene)...
atom. Enols are commonly used in condensation reactions, including the Claisen condensation and the aldolcondensation reactions.[citation needed] Examples...
The Darzens reaction (also known as the Darzens condensation or glycidic ester condensation) is the chemical reaction of a ketone or aldehyde with an...
equilibrate with cyclic hemiacetal. Monomeric glutaraldehyde polymerizes by aldolcondensation and Michael reactions yielding alpha, beta-unsaturated poly-glutaraldehyde...
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