The aldol reaction (aldol addition) is a reaction in organic chemistry that combines two carbonyl compounds (e.g. aldehydes or ketones) to form a new β-hydroxy carbonyl compound. Its simplest form might involve the nucleophilic addition of an enolized ketone to another:
These products are known as aldols, from the aldehyde + alcohol, a structural motif seen in many of the products. The use of aldehyde in the name comes from its history: aldehydes are more reactive than ketones, so that the reaction was discovered first with them.[2][3][4]
The aldol reaction is paradigmatic in organic chemistry and perhaps the most common means of forming carbon–carbon bonds in organic chemistry.[5][6][7] It lends its name to the family of aldol reactions and similar techniques analyze a whole family of carbonyl α-substitution reactions, as well as the diketone condensations. When the nucleophile and electrophile are different, the reaction is called a crossed aldol reaction; on the converse, when the nucleophile and electrophile are the same, the reaction is called an aldol dimerization.
Aldol structural units are found in many important molecules, whether naturally occurring or synthetic.[8][9] The reaction is used in several industrial syntheses, notably of pentaerythritol,[10] trimethylolpropane, the plasticizer 2-ethylhexanol, and the drug Lipitor (atorvastatin, calcium salt).[11] For many of the commodity applications, the stereochemistry of the aldol reaction is unimportant, but the topic is of intense interest for the synthesis of many specialty chemicals.
A typical experimental setup for an aldol reaction in a research laboratory. The flask on the right is a solution of lithium diisopropylamide (LDA) in tetrahydrofuran (THF). The flask on the left is a solution of the lithium enolate of tert-butyl propionate (formed by addition of LDA to tert-butyl propionate). An aldehyde can then be added to the enolate flask to initiate an aldol addition reaction. Both flasks are submerged in a dry ice/acetone cooling bath (−78 °C) the temperature of which is being monitored by a thermocouple (the wire on the left).
^Klein, David R. (December 22, 2020). Organic chemistry (4th ed.). Hoboken, NJ: Wiley. p. 1014. ISBN 978-1-119-65959-4. OCLC 1201694230.
^Cite error: The named reference Wurtz1872 was invoked but never defined (see the help page).
^Cite error: The named reference Wurtz1872b was invoked but never defined (see the help page).
^Cite error: The named reference Wurtz1872c was invoked but never defined (see the help page).
^Wade, L. G. (2005). Organic Chemistry (6th ed.). Upper Saddle River, New Jersey: Prentice Hall. pp. 1056–66. ISBN 978-0-13-236731-8.
^Smith, Michael B.; March, Jerry (2006). March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. doi:10.1002/0470084960. ISBN 9780470084960.
^Mahrwald, R. (2004). Modern Aldol Reactions, Volumes 1 and 2. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA. pp. 1218–23. ISBN 978-3-527-30714-2.
^Heathcock, C. H. (1991). "The Aldol Reaction: Acid and General Base Catalysis". In Trost, B. M.; Fleming, I. (eds.). Comprehensive Organic Synthesis. Vol. 2. Elsevier Science. pp. 133–179. doi:10.1016/B978-0-08-052349-1.00027-5. ISBN 978-0-08-052349-1.
^Paterson, I. (1988). "New Asymmetric Aldol Methodology Using Boron Enolates". Chem. Ind. 12: 390–394.
^Mestres R. (2004). "A green look at the aldol reaction". Green Chemistry. 6 (12): 583–603. doi:10.1039/b409143b.
^Jie Jack Li; et al. (2004). Contemporary Drug Synthesis. Wiley-Interscience. pp. 118–. ISBN 978-0-471-21480-9.
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The aldolreaction (aldol addition) is a reaction in organic chemistry that combines two carbonyl compounds (e.g. aldehydes or ketones) to form a new...
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...
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bond-formation reaction, giving them wide applicability as a pre-cursor for a variety of other compounds. Aldols are usually synthesized from an aldol addition...
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transformations termed Tandem Michael-aldolreactions, that sequentially combine Michael addition and aldolreaction into a single reaction. As is the case with Robinson...
active substrate; the reaction provides gramine derivatives. The Mannich reaction can be considered to involve a mixed-aldolreaction, dehydration of the...
with a C=C bond) and the resulting cyclobutane ring undergoes a retro-aldolreaction to yield a 1,5-diketone: The net effect is to add the two carbon atoms...
stereoselective transformations, including aldolreactions, alkylation reactions, and Diels-Alder reactions. The oxazolidinones are substituted at the...
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development of related reactions including the Michael addition, asymmetric aldolreaction, and the Mannich reaction. This reaction has likewise been used...
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β-unsaturated aromatic acid or α-substituted β-aryl acrylic acid by the aldol condensation of an aromatic aldehyde and an acid anhydride, in the presence...
deprotonation there, leading to enolates and possible aldolreactions. Under ideal conditions the reaction produces 50% of both the alcohol and the carboxylic...
beta-unsaturated aldehyde or ketone hydrolysis of the enamine back to a ketone The reaction also applies to acyl halides as electrophiles, which results in the formation...
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nucleophilic substitution, as well as being the co-discoverer of the aldolreaction. Borodin was a promoter of education in Russia and founded the School...
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enolate, or as an electrophile; the combination of the two is called the aldolreaction. Designing practically useful syntheses always requires conducting the...
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