Acetylacetone is a colorless liquid with a sweet smell. It is used as a solvent in pharmaceuticals, dyes and pigments, paints and coatings, and many other products. It is also a useful anti-corrosive agent, as it can bind with metals to form a protective barrier against the elements.
It can also form complexes with transition metal ions, where it acts as a metal chelating agent. The acetyl group of the molecule has two oxygen atoms with lone electron pairs that can donate to a central metal ion center. This results in a six-membered ring called a chelate. Complexes of this type are common with the second-row transition metals, such as cobalt (II) and nickel(II).
In coordination chemistry, acetylacetone functions as a bidentate ligand and is an important building block for heterocyclic compounds. It can also be used in the preparation of a variety of metal acetylacetonates, which are used as catalysts and reagents.
The formation of these metal acetylacetonates can be accomplished by reacting a higher-valent hydroxo or oxo metal with a stoichiometric amount of acetylacetone. The reaction is usually exothermic, and the pH of the solution will be 5.5 or lower. As the reaction proceeds, the acetylacetone will release its conjugate base, and a metal acetylacetonate will be formed. Typically, a buffer is not needed as the reaction is exothermic enough to make it proceed at a rapid rate without extraneous heating. A metal acetylacetonate can be isolated from the reaction mixture by recrystallization, and the process can be repeated.