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Skeletal formula of butanone
Ball-and-stick model of butanone
Space-filling model of butanone
methyl ethyl ketone
IUPAC name
Other names
Methyl ethyl ketone; MEK; 2-Butanone; Methylpropanone; Ethylmethylketone; Methylacetone
CAS number 78-93-3 YesY
ChEBI CHEBI:28398 YesY
ChemSpider 6321 YesY
Jmol-3D images Image
KEGG C02845 YesY
PubChem 6569
RTECS number EL6475000
Molar mass 72.11 g·mol−1
Appearance Colorless liquid
Odor mint or acetone-like[2]
Density 0.8050 g/cm3
Melting point −86 °C (−123 °F; 187 K)
Boiling point 79.64 °C (175.35 °F; 352.79 K)
27.5 g/100 mL
Vapor pressure 78 mmHg (20°C)[2]
Viscosity 0.43 cP
Dipole moment 2.76 D
MSDS External MSDS
EU classification Flammable (F)
Irritant (Xi)
R-phrases R11 R36 R66 R67
S-phrases (S2) S9 S16
NFPA 704
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasoline) Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity (yellow): no hazard code Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point −9 °C (16 °F; 264 K)
505 °C (941 °F; 778 K)
Explosive limits 1.4%-11.4%[2]
6.86 mL/kg (oral, rat)
US health exposure limits (NIOSH):
TWA 200 ppm (590 mg/m3)[2]
TWA 200 ppm (590 mg/m3) ST 300 ppm (885 mg/m3)[2]
3000 ppm[2]
Related compounds
Related Ketones
Acetone; 3-pentanone; 3-Methylbutanone
Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Phase behaviour
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY verify (what isYesY/N?)
Infobox references

Butanone, also known as methyl ethyl ketone or MEK, is an organic compound with the formula CH3C(O)CH2CH3. This colorless liquid ketone has a sharp, sweet odor reminiscent of butterscotch and acetone. It is produced industrially on a large scale, and also occurs in trace amounts in nature.[3] It is soluble in water and is commonly used as an industrial solvent.[4]


Oxidation of 2-butanol is one way to produce butanone. Butanone is produced by the dehydrogenation of 2-butanol using a catalyst based on copper, zinc, or bronze:


In this way, approximately 700M kg are produced yearly. Other routes that have been examined but not implemented include Wacker oxidation of 2-butene and oxidation of isobutylbenzene (analogous to the industrial route to acetone).[3]

Both liquid-phase oxidation of heavy naphtha and the Fischer-Tropsch reaction produce mixed oxygenate streams, from which 2-butanone is extracted by fractionation.[5]

Butanone is biosynthesized by some trees and found in some fruits and vegetables in small amounts. It is released to the air from car and truck exhausts.


As a solvent[edit]

Butanone is an effective and common solvent[4] and is used in processes involving gums, resins, cellulose acetate and nitrocellulose coatings and in vinyl films.[6] For this reason it finds use in the manufacture of plastics, textiles, in the production of paraffin wax, and in household products such as lacquer, varnishes, paint remover, a denaturing agent for denatured alcohol, glues, and as a cleaning agent. It has similar solvent properties to acetone but boils at a higher temperature and has a significantly slower evaporation rate.[7] Butanone is also used in dry erase markers as the solvent of the erasable dye.

As a plastic welding agent[edit]

As butanone dissolves polystyrene, it is sold as "model cement" for use in connecting together parts of scale model kits. Though often considered an adhesive, it is actually functioning as a welding agent in this context.

Other uses[edit]

Butanone is the precursor to methyl ethyl ketone peroxide, which is a catalyst for some polymerization reactions such as crosslinking of unsaturated polyester resins.


This chemical must be handled carefully.


Butanone can react with most oxidizing materials, and can produce fires.[4] It is moderately explosive; it requires only a small flame or spark to cause a vigorous reaction.[4] Butanone fires should be extinguished with carbon dioxide, dry chemicals or alcohol foam.[4] Concentrations in the air high enough to be flammable are also intolerable to humans due to the irritating nature of the vapour.[7]

Health effects[edit]

Butanone is an irritant, causing irritation to the eyes and nose of humans,[7] but serious health effects in animals have been seen only at very high levels. When inhaled, these effects included birth defects in mice, but only at the highest dose tested (3000 ppm for 7 hours/day).[8]

In 2005, the U. S. Environmental Protection Agency removed butanone from the list of hazardous air pollutants (HAPs). After technical review and consideration of public comments, EPA concluded that potential exposures to butanone emitted from industrial processes may not reasonably be anticipated to cause human health or environmental problems. However, some reviewers have advised caution in using methylethyl ketone because of reports of neuropsychological effects. [9]

Emissions of butanone will continue to be regulated as a volatile organic compound because of its contribution to the formation of tropospheric (ground-level) ozone.

Butanone is listed as a Table II precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances.[10]

See also[edit]


  1. ^ Merck Index, 11th Edition, 5991.
  2. ^ a b c d e f "NIOSH Pocket Guide to Chemical Hazards". National Institute for Occupational Safety and Health (NIOSH). id=0069. 
  3. ^ a b Wilhelm Neier, Guenter Strehlke "2-Butanone" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002.
  4. ^ a b c d e Turner, Charles F.; McCreery, Joseph W. (1981). The Chemistry of Fire and Hazardous Materials. Boston, Massachusetts: Allyn and Bacon, Inc. p. 118. ISBN 0-205-06912-6. 
  5. ^ Ashford's Dictionary of Industrial Chemicals, Third edition, 2011, ISBN 978-0-9522674-3-0, pages 6013-4
  6. ^ Apps, E. A. (1958). Printing Ink Technology. London: Leonard Hill [Books] Limited. p. 101. 
  7. ^ a b c Fairhall, Lawrence T. (1957). Industrial Toxicology. Baltimore: The Williams and Wilkins Company. pp. 172–173. 
  8. ^ Schwetz et al. (1991). "Developmental toxicity of inhaled methyl ethyl ketone in Swiss mice". Fund. Appl. Toxicol. 16 (4): 742–748. doi:10.1016/0272-0590(91)90160-6. 
  9. ^ Thompson, S.B.N. “Implications for cognitive rehabilitation and brain injury from exposure to Methyl Ethyl Ketone (MEK): a review.” Journal of Cognitive Rehabilitation 2010; 28(Winter): 4-14. doi: jofcr.com/vol284/v28i4thompson.pdf.
  10. ^ List of Precursors and Chemicals Frequently Used in the Illicit Manufacture of Narcotic Drugs and Psychotropic Substances Under International Control, International Narcotics Control Board

External links[edit]