1,3-Cyclohexanedione is an organic compound with the formula (CH<sub>2</sub>)<sub>4</sub>(CO)<sub>2</sub>. It is one of three isomeric cyclohexanediones. It is a colorless compound that occurs naturally. It is the substrate for cyclohexanedione hydrolase. The compound exists mainly as the enol tautomer.
1,3-Cyclohexanedione is produced by semi-hydrogenation of resorcinol:
1,3-Cyclohexanedione exists in solution predominantly as the enol tautomer.
It reacts under acid catalysis with alcohols to 3-alkoxyenones. Its pK<sub>a</sub> is 5.26. Treatment of the sodium salt of the enolate with methyl iodide gives 2-methyl-1,3-cyclohexanedione, which also exists predominantly as the enol.
Dimedone (5,5-dimethyl-1,3-cyclohexanedione) is a well established reagent.
Several herbicides against grasses are formal derivatives of 1,3-cyclohexanedione. Examples of commercial products include cycloxydim, clethodim, tralkoxydim, butroxydim, sethoxydim, profoxydim, and mesotrione.
1,3-Cyclohexanedione is also used in the manufacture of Ondansetron.