Acetylacetone

A beta-diketone with coupled carbonyl and enol chemistry.

Formula
C5H8O2
Molar mass
100.12 g/mol
Also known as
pentane-2,4-dione, 2,4-Pentanedione, 2,4-Dioxopentane, Acetoacetone, Diacetylmethane, ACAC

Overview

A beta-diketone with coupled carbonyl and enol chemistry.

The central methylene lies between two ketone groups. Its conjugate base delocalises charge across both carbonyl systems, increasing acidity relative to a simple ketone. Keto and enol forms are tautomers, not resonance structures, because a hydrogen changes position.

Identifiers

Formula
C5H8O2
Molar mass
100.12 g/mol
Also known as
pentane-2,4-dione, 2,4-Pentanedione, 2,4-Dioxopentane, Acetoacetone, Diacetylmethane, ACAC
Chemical identifiers
SMILES
CC(=O)CC(=O)C
InChI
InChI=1S/C5H8O2/c1-4(6)3-5(2)7/h3H2,1-2H3
PubChem CID
31261

Properties

Melting Point
-23 °C
Boiling Point
138 °C
Relative density (water = 1)
Relative density (water = 1): 0.98
Water solubility
In water, 166,000 mg/L at 20 °C

References

  1. PubChem Compound Summary: Acetylacetone (CID 31261)National Center for Biotechnology Information · PubChem

    Identity, molecular formula, molecular weight and aliases retrieved via PUG REST on 2026-09-08.

  2. OpenStax Organic Chemistry: Acidity of alpha hydrogen atoms: enolate ion formationJohn McMurry · OpenStax · 2023

    Supports the qualitative structure and reactivity context; identity and numerical measurements retain their original references.

  3. OpenStax Organic Chemistry: Keto–enol tautomerismJohn McMurry · OpenStax · 2023

    Supports the distinction between proton-transfer tautomerism and resonance forms.

  4. Hazardous Substances Data Bank (HSDB): Acetylacetone — melting pointHazardous Substances Data Bank (HSDB)

    Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/31261#section=Melting-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V4: 3857

  5. Hazardous Substances Data Bank (HSDB): Acetylacetone — boiling pointHazardous Substances Data Bank (HSDB)

    Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/31261#section=Boiling-Point. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V4: 3857

  6. ILO-WHO International Chemical Safety Cards (ICSCs): Acetylacetone — densityILO-WHO International Chemical Safety Cards (ICSCs)

    Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/31261#section=Density. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred.

  7. Hazardous Substances Data Bank (HSDB): Acetylacetone — solubilityHazardous Substances Data Bank (HSDB)

    Retrieved through PubChem PUG View on 2026-09-08. https://pubchem.ncbi.nlm.nih.gov/compound/31261#section=Solubility. Source value, complete property clause or compact miscibility statement retained; absent pressure, temperature or phase conditions are not inferred. Original reference: Riddick, J.A., W.B. Bunger, Sakano T.K. Techniques of Chemistry 4th ed., Volume II. Organic Solvents. New York, NY: John Wiley and Sons., 1985., p. 359