Acetylacetone
| Names | |
|---|---|
| IUPAC name
Pentane-2,4-dione
| |
| Other names
2,4-Dioxopentane
2,4-Pentanedione Acetyl acetone Acetoacetone Diacetylmethane Hacac Pentanedione | |
| Properties | |
| C5H8O2 CH3COCH2COCH3 | |
| Molar mass | 100.117 g/mol |
| Appearance | Colorless liquid |
| Odor | Ketone-like odor |
| Density | 0.975 g/cm3 (20 °C) |
| Melting point | −23 °C (−9 °F; 250 K) |
| Boiling point | 140 °C (284 °F; 413 K) |
| 16 g/100 ml | |
| Solubility | Reacts with bases Miscible with most organic solvents |
| Vapor pressure | 2.96 mmHg (20 °C) |
| Thermochemistry | |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Flash point | 34 °C (93 °F; 307 K) |
| Lethal dose or concentration (LD, LC): | |
| LD50 (Median dose)
|
570 mg/kg (rat, oral) |
| Related compounds | |
| Related compounds
|
Acetone |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Acetylacetone is an organic compound with the chemical formula CH3COCH2COCH3.
The compound exists in equilibrium with a tautomer CH3C(O)CH=(OH)CH3. These tautomers interconvert so rapidly under most conditions that they are treated as a single compound in most applications.
Contents
Properties
Chemical
The keto and enol tautomers of acetylacetone coexist in solution. The enol form has C2v symmetry, meaning the hydrogen atom is shared equally between the two oxygen atoms. The equilibrium constant tends to be high in nonpolar solvents; the keto form becomes more favorable in polar, hydrogen-bonding solvents, such as water. The enol form is a vinylogous analogue of a carboxylic acid.
Acetylacetone condenses with hydrazine to yield 3,5-dimethylpyrazole.
The acetylacetonate anion, acac−, forms complexes with many transition metal ions. A general method of synthesis is to treat a transition metal salt with acetylacetone in the presence of a base:[3]
- MBz + z Hacac ⇌ M(acac)z + z BH
Both oxygen atoms bind to the metal to form a six-membered chelate ring. In some cases the chelate effect is so strong that no added base is needed to form the complex.
Long term exposure to light will cause polymerization.
Acetylacetone is a weak acid.
Physical
Acetylacetone is a colorless liquid, slightly soluble in water.
Availability
Acetylacetone is sold by chemical suppliers.
Preparation
Acetylacetone is prepared industrially by the thermal rearrangement of isopropenyl acetate.[4]
Another route involves he reaction between acetone and acetic anhydride, with boron trifluoride being used catalyst.[5] Ethyl acetate an also be used.
Reaction between a mixture of acetone and methyl acetate with sodium hydride in anhydrous toluene for 7 h at 40 °C will yield acetylacetone.[6]
Projects
- Make 3,5-dimethylpyrazole
- Make transition metal coordination complexes
Handling
Safety
Acetylacetone is flammable, though due to its flash point of 34 °C it will not ignite easily if kept cold.
Acetylacetone is harmful if ingested. Its vapors may be irritant.
Storage
Should be stored in amber bottles, in a dark, well ventilated place.
Disposal
Should be mixed with a more flammable solvent, like ethanol or acetone and incinerated outside or in an incinerator.
References
- ↑ Gmehling; Becker; Aufderhaar; Journal of Chemical and Engineering Data; vol. 45; nb. 4; (2000); p. 661 - 664
- ↑ Nicholson; Journal of the Chemical Society; (1957); p. 2431
- ↑ http://homepages.gac.edu/~bobrien/Inorganic_Lab/acac/Co.tfa.3.&.Co.acac.3.handout.S01.pdf
- ↑ https://onlinelibrary.wiley.com/doi/10.1002/14356007.a15_077
- ↑ http://orgsyn.org/demo.aspx?prep=CV3P0016
- ↑ Liu, Xin; Cheng, Ran; Zhao, Feifei; Zhang-Negrerie, Daisy; Du, Yunfei; Zhao, Kang; Organic Letters; vol. 14; nb. 21; (2012); p. 5480 - 5483,4
