ketols

Ketols are a class of organic compounds that contain both a ketone functional group (C=O) and a hydroxyl group (OH) on adjacent carbon atoms. The proximity of the hydroxyl group to the carbonyl allows for the formation of intramolecular hydrogen bonds, which can stabilize the molecule and sometimes result in the formation of a cyclic hemiketal structure. Because of this arrangement, ketols often exist in equilibrium with related lactones or aldehydes through tautomeric shifts.

In many simple ketols, such as acetyl alcohol (CH3COCH2OH), the OH group can donate a proton to the adjacent carbonyl oxygen, forming an intramolecular hydrogen bond that reduces the reactivity of the carbonyl toward nucleophilic attack. This intramolecular stabilization also shifts the absorption characteristics of the compound, making ketols useful in spectroscopic studies of hydrogen bonding dynamics. In more complex ketols derived from sugars, the ketol form can interconvert with an aldehyde form, a process that underpins the Leloir pathway of carbohydrate metabolism.

Ketols are found in natural products, including various plant secondary metabolites where the ketol moiety contributes to biological activity such as antioxidant or anti-inflammatory effects. They also serve as synthetic intermediates in pharmaceutical chemistry, especially in the synthesis of epoxides, lactones, and heterocyclic compounds. Moreover, the unique hydrogen‑bonding patterns in ketols have made them valuable probes in studies of protein–ligand interactions and enzyme catalysis.

Overall, ketols illustrate the interplay between functional group positioning and molecular stability, and they remain an important motif in both natural biosynthesis and synthetic organic chemistry.