|Preferred IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||72.107 g·mol−1|
|Odor||Mint or acetone-like|
|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)|
Refractive index (nD)
|H225, H319, H336|
|P210, P233, P240, P241, P242, P243, P261, P264, P271, P280, P303+P361+P353, P304+P340, P305+P351+P338, P312, P337+P313, P370+P378, P403+P233, P403+P235, P405, P501|
|NFPA 704 (fire diamond)|
|Flash point||−9 °C (16 °F; 264 K)|
|505 °C (941 °F; 778 K)|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
LC50 (median concentration)
|NIOSH (US health exposure limits):|
|TWA 200 ppm (590 mg/m3)|
|TWA 200 ppm (590 mg/m3) ST 300 ppm (885 mg/m3)|
IDLH (Immediate danger)
|Safety data sheet (SDS)||Safety Data Sheet|
|Acetone; 3-pentanone; 3-methylbutanone|
|Supplementary data page|
|Butanone (data page)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
(what is ?)
Butanone, also known as methyl ethyl ketone (MEK) or ethyl methyl ketone,[a] is an organic compound with the formula CH3C(O)CH2CH3. This colorless liquid ketone has a sharp, sweet odor reminiscent of acetone. It is produced industrially on a large scale, but occurs in nature only in trace amounts. It is partially soluble in water, and is commonly used as an industrial solvent. It is an isomer of another solvent, tetrahydrofuran.
- CH3CH(OH)CH2CH3 → CH3C(O)CH2CH3 + H2
This is used to produce approximately 700 million kilograms yearly. Other syntheses that have been examined but not implemented include Wacker oxidation of 2-butene and oxidation of isobutylbenzene, which is analogous to the industrial production of acetone. The cumene process can be modified to produce phenol and a mixture of acetone and butanone instead of only phenol and acetone in the original.
Butanone is an effective and common solvent and is used in processes involving gums, resins, cellulose acetate and nitrocellulose coatings and in vinyl films. 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. Unlike acetone, it forms an azeotrope with water, making it useful for azeotropic distillation of moisture in certain applications. Butanone is also used in dry erase markers as the solvent of the erasable dye.
As butanone dissolves polystyrene and many other plastics, it is sold as "model cement" for use in connecting parts of scale model kits. Though often considered an adhesive, it is functioning as a welding agent in this context.
Butanone is the precursor to methyl ethyl ketone peroxide, which is a catalyst for some polymerization reactions such as crosslinking of unsaturated polyester resins. Dimethylglyoxime can be prepared from butanone first by reaction with ethyl nitrite to give diacetyl monoxime followed by conversion to the dioxime:
In the final step of the process, hydrolysis produces the desired product, hydrazine, and regenerates the butanone.
- Me(Et)C=NN=C(Et)Me + 2 H2O → 2 Me(Et)C=O + N2H4
Butanone can react with most oxidizing materials and can produce fires. It is moderately explosive, requiring only a small flame or spark to cause a vigorous reaction. The vapor is heavier than air, so it can accumulate at low points. It is explosive at concentrations between 1.4 and 11.4%. Concentrations in the air high enough to be flammable are intolerable to humans due to the irritating nature of the vapor. Butanone fires should be extinguished with carbon dioxide, dry agents, or alcohol-resistant foam.
Butanone is a constituent of tobacco smoke. It is an irritant, causing irritation to the eyes and nose of humans. Serious animal health effects have been seen only at very high levels. There are no long-term studies with animals breathing or drinking it, and no studies for carcinogenicity in animals breathing or drinking it.: 96 There is some evidence that butanone can potentiate the toxicity of other solvents, in contrast to the calculation of mixed solvent exposures by simply adding exposures.
As of 2010[update], the United States Environmental Protection Agency (EPA) listed butanone as a toxic chemical. There are reports of neuropsychological effects. It is rapidly absorbed through undamaged skin and lungs. It contributes to the formation of ground-level ozone, which is toxic in low concentrations.
Butanone is listed as a Table II precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances.
Emission of butanone was regulated in the US as a hazardous air pollutant, because it is a volatile organic compound contributing to the formation of tropospheric (ground-level) ozone. In 2005, the US Environmental Protection Agency removed butanone from the list of hazardous air pollutants (HAPs).
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- List of Precursors and Chemicals Frequently Used in the Illicit Manufacture of Narcotic Drugs and Psychotropic Substances Under International Control Archived February 27, 2008, at the Wayback Machine, International Narcotics Control Board
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- Barbara Kanegsberg (n.d.). "MEK No Longer a HAP". Bfksolutions newsletter. Archived from the original on 2 April 2015. Retrieved 2 April 2015. 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.
- "EPA De-Lists MEK from CAA HAP List". www.pcimag.com. Retrieved 2016-07-30.