User:TaroToro/Aldol
In organic chemistry, an aldol describes a structural motif consisting of a 3-hydroxy ketone or 3-hydroxyaldehyde. An aldol consisting of a 3-hydroxy ketone is called a β-hydroxy ketone, and an aldol consisting of a 3-hydroxy aldehyde is called a β-hydroxy aldehyde. Aldols are usually the product of aldol addition. When used alone, the term "aldol" may refer to 3-hydroxybutanal.[1]
Properties[edit]
Aldols derived from aldehydes (β-hydroxy aldehyde) have higher boiling points than its equivalent saturated compound.[2] This is because aldols have a hydroxyl group (-OH) and a carbonyl group (C=O) that allows for hydrogen bonding[2], while the saturated compound lacks the hydroxyl group.
Stereochemistry[edit]
Despite having only two functional groups, many aldols can have complicated structures arising from the relative positions of the OH group and the substituent between it and the carbonyl.[3] Controlling reactions in order to favor the formation of one of these isomers is of great interest in the area of asymmetric synthesis.
Reactions[edit]
The chemistry of aldols is dominated by one reaction, dehydration:
RC(O)CH2CH(OH)R' → RC(O)CH=CHR' + H2O
At room temperature, aldols release water.
Dehydration of aldols.
Applications[edit]
When two molecules of aldehydes react to form an aldol (β-hydroxy aldehyde), the aldol usually produces secondary compounds since it is unstable.[2] Secondary compounds can be diols, unsaturated aldehydes, or alcohols.[2] This is an example of intermolecular addition.[2]
Aldols can be used as starting materials. 3-hydroxybutanal can synthesize quinaldine, which is used to make dyes such as quinoline Yellow SS.[2]
Aldols are also used as intermediates in the synthesis of natural products and medication.[5][6] The synthesis of Oseltamivir, an antiviral medicine used to treat the flu, involves the aldol reaction.[7]
The structural motif of aldols is often found in polyketide natural products, which can be used to manufacture antibiotics.[5]
Hydroxypivaldehyde is a rare example of a relatively robust aldol. The chemical structure of hydroxypivaldehyde stays the same even after being distilled because of its bulkiness, making it robust.[8][9]
References[edit]
- ^ PubChem. "CID 21282929". National Center for Biotechnology Information. Retrieved 2023-04-15.
- ^ a b c d e f Kohlpaintner, Christian; Schulte, Markus; Falbe, Jürgen; Lappe, Peter; Weber, Jürgen; Frey, Guido D. (15 January 2013). "Aldehydes, Aliphatic". Ullmann's encyclopedia of industrial chemistry (7). doi:10.1002/14356007.a01_321.pub3. Retrieved 1 April 2023 – via Wiley Online Library.
- ^ Smith, Michael B.; March, Jerry (2007). March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure (6th ed.). New York: Wiley-Interscience. p. 1345. ISBN 978-0-471-72091-1.
- ^ Ashenhurst, James. "Aldol Addition and Condensation Reactions". Master Organic Chemistry. Retrieved 15 April 2023.
- ^ a b Schetter, Bernd; Mahrwald, Rainer (2006). "Modern aldol methods for the total synthesis of polyketides". Angewandte Chemie (International ed. in English). 45: 7506-25. doi:10.1002/anie.200602780.
- ^ Ghosh, Arun K.; Dawson, Zachary L. (2009). "Synthesis of Bioactive Natural Products by Asymmetric syn- and anti-Aldol Reactions". Synthesis. 17: 2992-3002. doi:10.1055/s-0029-1216941.
- ^ Ko, Ji S.; Keum, Ji E.; Ko, Soo Y. (15 October 2010). "A synthesis of oseltamivir (Tamiflu) starting from D-mannitol". J Org Chem. 75 (20): 7006–9. doi:10.1021/jo101517g – via National Library of Medicine.
- ^ Zhang, Yanping; Mu, Hongliang; Pan, Li; Wang, Xuling; Li, Yuesheng (May 21, 2018). "Robust Bulky [P,O] Neutral Nickel Catalysts for Copolymerization of Ethylene with Polar Vinyl Monomers". ACS Catal. 8: 5963–5976. doi:10.1021/acscatal.8b01088.
- ^ "distillable". Merriam-Webster. Retrieved 15 April 2023.