Isomerism and StereochemistryhardNUMERICAL

In the liquid state, what is the approximate percentage (%) of the enol form present in the tautomerIsomerism and Stereochemistry Chemistry Question

Question

In the liquid state, what is the approximate percentage (%) of the enol form present in the tautomeric equilibrium mixture of acetylacetone (pentane-2,4-dione)?

Answer: 76

💡 Solution & Explanation

While simple mono-ketones heavily favor the keto form (~99%), $\beta$ -diketones like acetylacetone exhibit a much higher enol content due to resonance stabilization and a stable 6-membered intramolecularly hydrogen-bonded pseudo-ring. In the liquid state, its tautomeric mixture consists of roughly 24% keto form and 76% enol form.

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