Diketone

A diketone or dione is a molecule containing two ketone groups. The simplest diketone is diacetyl, also known as 2,3-butanedione. Diacetyl, acetylacetone, and hexane-2,5-dione are examples of 1,2-, 1,3-, and 1,4-diketones, respectively. Dimedone is an example of a cyclic diketone. A diketone or dione is a molecule containing two ketone groups. The simplest diketone is diacetyl, also known as 2,3-butanedione. Diacetyl, acetylacetone, and hexane-2,5-dione are examples of 1,2-, 1,3-, and 1,4-diketones, respectively. Dimedone is an example of a cyclic diketone. An important member is biacetyl, CH3C(O)C(O)CH3. These compounds are often generated by dehydrogenation of the diols: A distinctive feature of 1,2-diketones is the long C-C bond linking the carbonyl groups. This bond distance is about 1.54 Å, compared to 1.45 Å for the corresponding bond in 1,3-butadiene. The effect is attributed to repulsion between the partial positive charges of the carbonyl carbon atoms. 1,2-Diketones condense with many bifunctional nucleophiles, such as urea and thiourea to give heterocycles. Upon condensation with aromatic amines, they convert to the diketimine ligands. An important member is acetylacetone, CH3C(O)CH2C(O)CH3. Acetylacetone is prepared industrially by the thermal rearrangement of isopropenylacetate.