Methyl isobutyl ketone

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Methyl isobutyl ketone
Skeletal formula of methyl isobutyl ketone
Ball-and-stick model of the methyl isobutyl ketone molecule
Preferred IUPAC name
Other names
4-Methyl-2-pentanone, Isopropylacetone, Hexone, Isobutyl methyl ketone, 2-Methylpropyl methyl ketone, 4-Methyl-2-oxopentane, MIK, Isobutylmethyl ketone, MIBK, Isohexanone
3D model (JSmol)
ECHA InfoCard 100.003.228
EC Number
  • 203-550-1
RTECS number
  • SA9275000
Molar mass 100.16 g/mol
Appearance colorless liquid
Odor pleasant[1]
Density 0.802 g/mL, liquid
Melting point −84.7 °C (−120.5 °F; 188.5 K)
Boiling point 117 to 118 °C (243 to 244 °F; 390 to 391 K)
1.91 g/100 mL (20 °C)
Vapor pressure 16 mmHg (20 °C)[1]
-70.05·10−6 cm3/mol
Viscosity 0.58 cP at 20.0 °C
2.8 D
Flammable (F)
Harmful (Xn)
R-phrases (outdated) R11, R20, R36/37, R66
S-phrases (outdated) (S2), S9, S16, S29
NFPA 704 (fire diamond)
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. gasolineHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity (yellow): no hazard codeSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point 14 °C (57 °F; 287 K)
449 °C (840 °F; 722 K)
Explosive limits 1.2–8.0% (93 °C)[1]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 100 ppm (410 mg/m3)[1]
REL (Recommended)
TWA 50 ppm (205 mg/m3) ST 75 ppm (300 mg/m3)[1]
IDLH (Immediate danger)
500 ppm[1]
Related compounds
Related ketones
Methyl isopropyl ketone
Diisobutyl ketone
Related compounds
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

Methyl isobutyl ketone (MIBK) is the organic compound with the formula (CH3)2CHCH2C(O)CH3. This colourless liquid, a ketone, is used as a solvent for gums, resins, paints, varnishes, lacquers, and nitrocellulose.[2]


Methyl isobutyl ketone is made from acetone via a three-step process. Firstly acetone undergoes an aldol reaction to give diacetone alcohol, which readily dehydrates to give mesityl oxide. Mesityl oxide can then be hydrogenated to give MIBK:

Synthesis of MIBK from acetone

Industrially, these three steps are combined. Acetone is treated with a strong acidic, palladium-doped cation exchange resin under medium pressure of hydrogen.[3] Several million kilograms are produced annually.[4] In 2003, the industrial production capacity for MIBK in the United States was 88,000 tons.[5]


MIBK tank car in Europe.

MIBK is used as a solvent for nitrocellulose, lacquers, and certain polymers and resins.[4]

Precursor to 6PPD[edit]

Another major use is as a precursor to N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylene diamine (6PPD), an antiozonant used in tires. 6PPD is prepared by reductive coupling of MIBK with 4-aminodiphenylamine.[6]

Solvent and niche applications[edit]

Unlike the other common ketone solvents, acetone and MEK, MIBK has quite low solubility in water, making it useful for liquid-liquid extraction. It has a similar polarity to ethyl acetate, but greater stability towards aqueous acid and base. It can be used to extract gold, silver and other precious metals from cyanide solutions, such as those found at gold mines, to determine the levels of those dissolved metals. Diisobutyl ketone (DIBK), a related lipophilic ketone, is also used for this purpose. Methyl isobutyl ketone is also used as a denaturing agent for denatured alcohol. When mixed with water or isopropyl alcohol MIBK serves as a developer for PMMA electron beam lithography resist. MIBK is used as a solvent for CS in the preparation of the CS spray used currently by British police forces.[7]


  1. ^ a b c d e f NIOSH Pocket Guide to Chemical Hazards. "#0326". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ US EPA. "Methyl Isobutyl Ketone (Hexone)". Retrieved 13 December 2015.
  3. ^ [1], Uhde Technology Profile: MIBK
  4. ^ a b Stylianos Sifniades, Alan B. Levy, "Acetone" in Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.
  5. ^ International Agency for Research on Cancer. "Methyl Isobutyl Ketone" (PDF). Retrieved 13 December 2015.
  6. ^ Hans-Wilhelm Engels et al., "Rubber, 4. Chemicals and Additives" in Ullmann's Encyclopedia of Industrial Chemistry, 2007, Wiley-VCH, Weinheim. doi:10.1002/14356007.a23_365.pub2
  7. ^ Peter J Gray; Stark, MM; Gray, P. J; Jones, G R. N (2000). "Is CS spray dangerous? : CS is a particulate spray, not a gas" (Response to editorial). BMJ. 321 (7252): 26. doi:10.1136/bmj.321.7252.46. PMC 1127688. PMID 10939811.

External links[edit]