|Jmol-3D images||Image 1|
|Molar mass||86.0892 g/mol|
|Appearance||Yellowish green liquid|
|Density||0.990 g/mL at 15 °C|
|Melting point||−2 to −4 °C|
|Boiling point||88 °C|
|Solubility in water||Soluble in 4 parts|
|R-phrases||R10 R22 R36 R37 R38|
|S-phrases||S9 S16 S33|
|Main hazards||Harmful, flammable|
(what is: / ?)|
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Diacetyl (IUPAC systematic name: butanedione or butane-2,3-dione) is an organic compound with the chemical formula (CH3CO)2. It is a volatile, colourless liquid with an intensely buttery flavor. It is a vicinal diketone (two C=O groups, side-by-side) with the molecular formula C4H6O2. Diacetyl occurs naturally in alcoholic beverages and is added to some foods to impart its buttery flavor.
A distinctive feature of diacetyl (and other 1,2-diketones) is the long C-C bond linking the carbonyl centers. This bond distance is about 1.54 Å, compared to 1.45 Å for the corresponding C-C bond in 1,3-butadiene. The elongation is attributed to repulsion between the polarized carbonyl carbon centers.