| Butanone[1] | |
|---|---|
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Butan-2-one |
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Other names
Methyl ethyl ketone; MEK; 2-Butanone; Methylpropanone; Ethylmethylketone; Methylacetone |
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| Identifiers | |
| CAS number | 78-93-3 |
| PubChem | 6569 |
| ChemSpider | 6321 |
| UNII | 6PT9KLV9IO |
| KEGG | C02845 |
| ChEBI | CHEBI:28398 |
| ChEMBL | CHEMBL15849 |
| RTECS number | EL6475000 |
| Jmol-3D images | Image 1 Image 2 |
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| Properties | |
| Molecular formula | C4H8O |
| Molar mass | 72.11 g mol−1 |
| Appearance | Colorless liquid |
| Density | 0.8050 g/cm3 |
| Melting point |
-86 °C, 187 K, -123 °F |
| Boiling point |
79.64 °C, 353 K, 175 °F |
| Solubility in water | 27.5 g/100 mL |
| Refractive index (nD) | 1.37880 |
| Viscosity | 0.43 cP |
| Structure | |
| Dipole moment | 2.76 D |
| Hazards | |
| MSDS | External MSDS |
| EU classification | Flammable (F) Irritant (Xi) |
| R-phrases | R11 R36 R66 R67 |
| S-phrases | (S2) S9 S16 |
| NFPA 704 |
3
1
0
|
| Flash point | −9 °C |
| Autoignition temperature |
505 °C |
| LD50 | 6.86 mL/kg (oral, rat) |
| Related compounds | |
| Related Ketones | Acetone; 3-pentanone; 3-Methylbutanone |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| 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.[2] It is soluble in water and is commonly used as an industrial solvent.[3]
Contents |
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).[2]
Both liquid-phase oxidation of heavy naphtha and the Fischer-Tropsch reaction produce mixed oxygenate streams, from which 2-butanone is extracted by fractionation.[4]
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.
Butanone is an effective and common solvent[3] and is used in processes involving gums, resins, cellulose acetate and nitrocellulose coatings and in vinyl films.[5] 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 has a significantly slower evaporation rate.[6] Butanone is also used in dry erase markers as the solvent of the erasable dye.
As butanone dissolves polystyrene, it is sold as "polystyrene 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.
Butanone is the precursor to methyl ethyl ketone peroxide, a catalyst for some polymerization reactions. It can also initiate crosslinking of unsaturated polyester resins.
Butanone can react with most oxidizing materials, and can produce fires.[3] It is moderately explosive; it requires only a small flame or spark to cause a vigorous reaction.[3] Butanone fires should be extinguished with carbon dioxide, dry chemicals or alcohol foam.[3] Concentrations in the air high enough to be flammable are also intolerable to humans due to the irritating nature of the vapour.[6]
Butanone is an irritant, causing irritation to the eyes and nose of humans,[6] but serious health effects in animals have been seen only at very high levels. When inhaled, these effects included birth defects.[7]
Butanone is listed as a Table II precursor under the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances.[8]
On December 19, 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. 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.