Tautomers of Acetylacetone (C₅H₈O₂)

Usually the keto tautomer is favored

Keto = ketone

Enol = alcohol

may also be referred to as an alkenol

The basic reaction

Keto Acetylacetone

With geometry optimization

PubChem's 3D structure has both oxygens pointing in the same direction (left) while NIST has the oxygens pointing in different directions (right)

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Proton NMR (Hartree-Fock)

Proton NMR (Hartree-Fock)