Lactol

In organic chemistry, a lactol is the functional group formed by the intramolecular nucleophilic addition of a hydroxyl group to an aldehyde. A lactol is the cyclic equivalent of a hemiacetal.

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.

Chemical reactivity

Lactols can participate in a variety of chemical reactions including: [cite journal| title=Oxidation, reduction and deoxygenation of carbohydrates |author=Lundt, Inge |journal=Glycoscience |year=2001 |issue=1 |pages=501-531]
* 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

References