Methyl isobutyl ketone

Methyl isobutyl ketone (MIBK) is the common name for the organic compound 4-methylpentan-2-one, condensed chemical 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
Skeletal formula of methyl isobutyl ketone
Ball-and-stick model of the methyl isobutyl ketone molecule
Names
Preferred IUPAC name
4-Methylpentan-2-one
Other names
4-Methyl-2-pentanone, Isopropylacetone, Hexone, Isobutyl methyl ketone, 2-Methylpropyl methyl ketone, 4-Methyl-2-oxopentane, MIK, Isobutylmethyl ketone, MIBK, Isohexanone
Identifiers
3D model (JSmol)
Abbreviations MIBK
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.228
EC Number
  • 203-550-1
KEGG
RTECS number
  • SA9275000
UNII
UN number 1245
  • InChI=1S/C6H12O/c1-5(2)4-6(3)7/h5H,4H2,1-3H3 ☒N
    Key: NTIZESTWPVYFNL-UHFFFAOYSA-N ☒N
  • InChI=1/C6H12O/c1-5(2)4-6(3)7/h5H,4H2,1-3H3
    Key: NTIZESTWPVYFNL-UHFFFAOYAQ
  • CC(C)CC(=O)C
Properties
C6H12O
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
1.3958
Viscosity 0.58 cP at 20.0 °C
Structure
2.8 D
Hazards
GHS labelling:
GHS02: FlammableGHS07: Exclamation markGHS08: Health hazard
Danger
H225, H319, H332, H335, H351
P210, P233, P240, P241, P242, P243, P261, P264, P271, P280, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P312, P337+P313, P370+P378, P403+P233, P403+P235, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
2
3
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
2-Pentanone
Diisobutyl ketone
Related compounds
 2-Methylpentan-4-ol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Infobox references

Production

At laboratory scale, MIBK can be produced via a three-step process using acetone as the starting material. Self-condensation, a type of aldol reaction, produces diacetone alcohol,[3] which readily dehydrates to give 4-methylpent-3-en-2-one (commonly, mesityl oxide).[4] Mesityl oxide is then hydrogenated to give MIBK.[5]

Synthesis of MIBK from acetone

Industrially, these three steps are combined. Acetone is treated with a strongly acidic, palladium catalyst-doped cation exchange resin under medium pressure of hydrogen.[6] Several million kilograms are produced annually.[5]

Uses
MIBK tank car in Europe.

MIBK is used as a solvent for nitrocellulose, lacquers, and certain polymers and resins.[5]

Precursor to 6PPD

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.[7]

Solvent and niche applications

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 American and British police forces.[8][9]

References
  1. NIOSH Pocket Guide to Chemical Hazards. "#0326". National Institute for Occupational Safety and Health (NIOSH).
  2. United States Environmental Protection Agency (September 2016). "Methyl Isobutyl Ketone (Hexone)". Retrieved 2015-12-13.
  3. Conant, J. B.; Tuttle, N. (1921). "Diacetone Alcohol". Organic Syntheses. 1: 45. doi:10.15227/orgsyn.001.0045.
  4. Conant, J. B.; Tuttle, N. (1921). "Mesityl Oxide". Organic Syntheses. 1: 53. doi:10.15227/orgsyn.001.0053.
  5. Stylianos Sifniades, Alan B. Levy, "Acetone" in Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005.
  6. Uhde GmbH (2005). "Uhde Technology Profile: MIBK" (PDF). Archived from the original (PDF) on 2013-12-03. Retrieved 18 October 2021.
  7. 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
  8. 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.
  9. Roger Eardley-Pryor (2017). "A Tear Gas Tale". Science History Institute. Retrieved 2021-02-22.
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