In organic chemistry, 3-hydroxybutanal (acetaldol, aldol) is an organic compound with the formula CH3CH(OH)CH2CHO and the structure H3C−CH(OH)−CH2−CH=O. It is classified as an aldol (R−CH(OH)−CHR'−C(=O)−R") and the word "aldol" can refer specifically to 3-hydroxybutanal. It is formally the product of the dimerization of acetaldehyde (CH3CHO). A thick colorless or pale-yellow liquid, it is a versatile and valuable intermediate with diverse impacts.[2] The compound is chiral although this aspect is not often exploited.
Production
Acetaldehyde dimerizes upon treatment with aqueous sodium hydroxide:[2]
- 2 CH3CHO → CH3CH(OH)CH2CHO + H2O
This is the prototypical aldol reaction.
Reactions and uses
Dehydration of 3-hydroxybutanal gives crotonaldehyde. Distillation of 3-hydroxybutanal is sufficiently forcing to effect this conversion:[2]
- CH3CH(OH)CH2CHO → CH3CH=CHCHO + H2O
Hydrogenation of 3-hydroxybutanal gives 1,3-butanediol:
- CH3CH(OH)CH2CHO + H2 → CH3CH(OH)CH2CH2OH
This diol is a precursor to 1,3-butadiene, precursor to diverse polymers.
Polymerization of 3-hydroxybutanal is also spontaneous, but can be stopped with the addition of water.
Aldol has been used in making perfumes and in ore flotation.[3]
Former or niche uses
It was formerly used in medicine as a hypnotic and sedative.[4]
See also
References
- ^ "3-hydroxybutanal – Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. Retrieved 13 October 2011.
- ^ a b c Kohlpaintner, Christian; Schulte, Markus; Falbe, Jürgen; Lappe, Peter; Weber, Jürgen (2008). "Aldehydes, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_321.pub2. ISBN 978-3527306732.
- ^ American Heritage Dictionary, 1973.
- ^ Hans Brandenberger, Robert A. A. Maes. (1997). Analytical Toxicology: For Clinical, Forensic, and Pharmaceutical Chemists. New York: de Gruyter.
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