Illustrated Glossary of Organic Chemistry

Enol: A molecule which has a hydroxyl group (OH) group directly bonded to an alkene (C=C). The name is a contraction derived from alkene alcohol. Enolization is the process of converting a molecule containing a carbonyl group into the corresponding enol tautomer.

General enol structure.

2-Hydroxypropene (a typical enol) is the enol tautomer of acetone. The enol moiety is shown in red.


Ascorbic acid (vitamin C; a hydrophilic antioxidant) has two enols (each shown in red).