Acetylacetone is an organic compound with the formula CH3COCH2COCH3. It is a colorless liquid classified as a 1,3-diketone. It is in equilibrium with the tautomer CH3C(O)CH=(OH)CH3. These tautomers interconvert in most cases so rapidly that they are considered a single compound in most applications. [2] It is a colorless liquid that is the precursor of the acetylacetonate anion (often abbreviated acac-), a bidentate ligand. It is also the basic material for the synthesis of heterocyclic compounds.
The ketone and enol tautomers of acetylacetone coexist in solution. The enol form has C2v symmetry, which means that the hydrogen atom is shared equally between the two oxygen atoms. [4] In the gas phase, the equilibrium constant Kketo?enol is 11.7, favoring the enol form. These two tautomers can be distinguished by nuclear magnetic resonance spectroscopy, infrared spectroscopy and other methods [5][6].

The equilibrium constant tends to be high in nonpolar solvents; when k = >1, the enol form is favored. The ketone form becomes more favorable in polar hydrogen-bonding solvents such as water. [7] The enol form is the alkenyl analog of the carboxylic acid.
Acetylacetone is a weak acid:

C5H8O2 ? C5H7O?2+ H+
The IUPAC recommended pKa values for this equilibrium in aqueous solution at 25 °C are 8.99 ± 0.04 (I = 0), 8.83 ± 0.02 (I = 0.1 M NaClO4) and 9.00 ± 0.03 (I = 1.0 M NaClO4; I = ionic strength) . [9] Values for mixed solvents are available. Very strong bases, such as organolithium compounds, will deprotonate acetylacetone twice. The resulting dilithium species can then be alkylated at C-1.
Acetylacetone is produced industrially by thermal rearrangement of isopropenyl acetate.
The laboratory route to acetylacetone also starts with acetone. Acetone and acetic anhydride after addition of boron trifluoride (BF3) catalyst:
Due to the ease of these syntheses, many analogs of acetylacetone are known. Some examples include benzoylacetone, dibenzoylmethane (dbaH), and the tert-butyl analog tetramethyl-3,5-heptanedione. Trifluoroacetylacetone and hexafluoroacetylacetone are also used to form volatile metal complexes.
In the latter reaction, an excess of carboxylic acid or chelating reagent such as acetylacetone (Fig. 33C), diol, or aminoalcohol produces a more soluble, higher MW, and processible material. The bulk of the evidence suggests that the products are highly crosslinked network structures. These preceramic polymers are used to prepare high-performance alumina (Al2O3) fibers. Generally, Alsingle bondO polymers range from gums to brittle solids. In addition to ceramic fibers, they have applications as lubricants, fuel additives, catalysts, gelling and drying agents, water repellants, and additives to paints and varnishes. If oxygen in the backbone is replaced with NH or NR, the polymers are thermally unstable and sensitive to acids, bases, and water.

A variety of Alsingle bondOsingle bondSisingle bondO polymers, poly(aluminosiloxanes), with Si:Al ratios from 0.8 to 23, are known. These materials are prepared by the reaction of sodium oligo(organosiloxanate)s with AlCl3 [Eq. (28)]: