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Skeletal formula of hexane-2,5-dione
Preferred IUPAC name
Other names
Acetonyl acetone
3D model (JSmol)
ECHA InfoCard 100.003.400
RTECS number MO3150000
Molar mass 114.1438 g mol−1
Appearance colorless liquid
Density 0.973 g cm−3, liquid
Melting point −5.5 °C (22.1 °F; 267.6 K)
Boiling point 191.4 °C (376.5 °F; 464.5 K)
≥ 10 g/100 mL (22 °C)
-62.51·10−6 cm3/mol
trigonal planar at carbonyl
tetrahedral elsewhere
Flash point 78 °C (172 °F; 351 K)
Related compounds
Related diketones
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

2,5-Hexanedione (Acetonylacetone) is an aliphatic diketone. In humans, it is a toxic metabolite of hexane and of 2-hexanone.

Symptoms of poisoning[edit]

The chronic toxicity of hexane is attributed to hexane-2,5-dione. The symptoms are tingling and cramps in the arms and legs, followed by general muscular weakness. In severe cases, atrophy of the skeletal muscles is observed, along with a loss of coordination and vision problems.[1]

Similar symptoms are observed in animal models. They are associated with a degeneration of the peripheral nervous system (and eventually the central nervous system), starting with the distal portions of the longer and wider nerve axons.

Mechanism of action[edit]

It appears that the neurotoxicity of 2,5-hexanedione resides in its γ-diketone structure since 2,3-, 2,4-hexanedione and 2,6-heptanedione are not neurotoxic, while 2,5-heptanedione and 3,6-octanedione and other γ-diketones are neurotoxic.[2] In fact, higher α-diketones, like 2,3-pentanedione and 2,3-hexanedione, are found in small amounts in various foods. They are used as aroma components in alcohol-free beverages and in baked goods.[3]

2,5-Hexanedione reacts with critical lysine residues in axonal proteins by Schiff base formation followed by cyclization to give pyrroles. Oxidation of the pyrrole residues then causes cross-linking between two n-hexane-modified proteins. The resulting denaturation of proteins perturbs axonal transport and function and causes damage to nerve cells.[4]


A Process for preparing 2,5-hexanedione has been described:[5][6]


Acetonylacetone can be used in the synthesis of isocarboxazid,[7] rolgamidine,[8] and mopidralazine.


  1. ^ Couri D, Milks M. "Toxicity and metabolism of the neurotoxic hexacarbons n-hexane, 2-hexanone, and 2,5-hexanedione" Annu. Rev. Pharmacol. Toxicol. 1982;22:145-66.
  2. ^ Stephen R Clough; Leyna Mulholland (2005), "Hexane", Encyclopedia of Toxicology, 2 (2nd ed.), Elsevier, pp. 522–525
  3. ^ Hardo Siegel; Manfred Eggersdorfer (2007), "Ketones", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, p. 16
  4. ^ Wolfgang Dekant; Spiridon Vamvakas (2007), "Toxicology", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, p. 23
  5. ^ U.S. Patent 3,819,714
  6. ^ http://www.prepchem.com/synthesis-of-2-5-hexanedione/ Primary: Systematic organic chemistry, by W. M. Cumming, 194, 1937.
  7. ^ U.S. Patent 2,908,688
  8. ^ U.S. Patent 4,140,793