Butanone

Butanone^[1]
Ball-and-stick model of butanone	Space-filling model of butanone
Names
	Preferred IUPAC name Butan-2-one
	Other names Ethyl methyl ketone; Ethylmethylketone; Methyl ethyl ketone (MEK; deprecated); Methylpropanone; Methylacetone;
Identifiers
CAS Number	78-93-3 ;
3D model (JSmol)	Interactive image; Interactive image;
Beilstein Reference	741880
ChEBI	CHEBI:28398 ;
ChEMBL	ChEMBL15849 ;
ChemSpider	6321 ;
ECHA InfoCard	100.001.054
Gmelin Reference	25656
KEGG	C02845 ;
PubChem CID	6569;
RTECS number	EL6475000;
UNII	6PT9KLV9IO ;
CompTox Dashboard (EPA)	DTXSID3021516 ;
	SMILES O=C(C)CC; CCC(=O)C;
Properties
Chemical formula	C4H8O
Molar mass	72.11 g·mol−1
Appearance	Colorless liquid
Odor	Mint or acetone-like
Density	0.8050 g/mL
Melting point	−86 °C (−123 °F; 187 K)
Boiling point	79.64 °C (175.35 °F; 352.79 K)
Solubility in water	27.5 g/100 mL
log P	0.37
Vapor pressure	78 mmHg (20 °C)
Acidity (pKa)	14.7
Magnetic susceptibility (χ)	−45.58·10−6 cm3/mol
Refractive index (nD)	1.37880
Viscosity	0.43 cP
Structure
Dipole moment	2.76 D
Hazards
EU classification	Flammable (F); Irritant (Xi)
	3 1 0
R-phrases	R11 R36 R66 R67
S-phrases	(S2) S9 S16
Explosive limits	1.4–11.4%
U.S. Permissible; exposure limit (PEL)	TWA 200 ppm (590 mg/m3)
Related compounds
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	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Butanone, also called methyl ethyl ketone (MEK), is an organic compound with the chemical formula C H₃C(O)CH₂CH₃. It is a simple ketone with four carbon atoms. It smells sharp and sweet, like butterscotch and acetone mixed. It is soluble in water and is used as a solvent.