Lactol
Functional group >C(OH)O, on a cyclic compound
In organic chemistry, a lactol is a functional group which is the cyclic equivalent of a hemiacetal (−CH(OH)O−) or a hemiketal (>C(OH)O−). The compound is formed by the intramolecular, nucleophilic addition of a hydroxyl group (−OH) to the carbonyl group (C=O) of an aldehyde (−CH=O) or a ketone (>C=O).
A lactol is often found as an equilibrium mixture with the corresponding hydroxyaldehyde. The equilibrium can favor either direction depending on ring size and other conformational effects.
The lactol functional group is prevalent in nature as component of aldose sugars.
01Chemical reactivity
Lactols can participate in a variety of chemical reactions including:
- Oxidation to form lactones
- Reaction with alcohols to form acetals
- The reaction of sugars with alcohols or other nucleophiles leads to the formation of glycosides
- Reduction (deoxygenation) to form cyclic ethers
Sources and credits
This article is adapted from the Wikipedia article “Lactol”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Lactol group in ribose.png by Edgar181, Public domain
- Lactol equilibrium.png by Edgar181, Public domain
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