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Cumene

From Wikipedia, the free encyclopedia
Not to be confused with cumin or cumulene.
Cumene
Skeletal formula of cumene
Ball-and-stick model of the cumene molecule
Names
Preferred IUPAC name
(Propan-2-yl)benzene[1]
Other names
  • Isopropylbenzene
  • Cumol
  • (1-Methylethyl)benzene
Identifiers
3D model (JSmol)
1236613
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.458 Edit this at Wikidata
EC Number
  • 202-704-5
KEGG
RTECS number
  • GR8575000
UNII
UN number 1918
  • InChI=1S/C9H12/c1-8(2)9-6-4-3-5-7-9/h3-8H,1-2H3 checkY
    Key: RWGFKTVRMDUZSP-UHFFFAOYSA-N checkY
  • InChI=1/C9H12/c1-8(2)9-6-4-3-5-7-9/h3-8H,1-2H3
    Key: RWGFKTVRMDUZSP-UHFFFAOYAJ
  • CC(C)c1ccccc1
Properties
C9H12
Molar mass 120.195 g·mol−1
Appearance Colorless liquid
Odor Sharp, gasoline-like
Density 0.862 g cm−3, liquid
Melting point −96 °C (−141 °F; 177 K)
Boiling point 152 °C (306 °F; 425 K)
negligible
Solubility soluble in acetone, ether, ethanol
Vapor pressure 4.5 mmHg (25 °C)[2]
-89.53·10−6 cm3/mol
1.4915 (20 °C)
Viscosity 0.777 cP (21 °C)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 flammable
GHS labelling:
GHS02: FlammableGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
Warning
H226, H302, H304, H312, H314, H332, H335, H341, H412, H441
P201, P202, P260, P261, P264, P270, P271, P273, P280, P281, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P308+P313, P310, P312, P321, P322, P330, P363, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 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. gasolineInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
2
3
1
Flash point 43 °C (109 °F; 316 K)
424 °C (795 °F; 697 K)
Explosive limits 0.9-6.5%
Lethal dose or concentration (LD, LC):
12750 mg/kg (oral, mouse)
1400 mg/kg (oral, rat)[4]
200 ppm (mouse, 7 hr)[4]
8000 ppm (rat, 4 hr)[4]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 50 ppm (245 mg/m3) [skin][3]
REL (Recommended)
 TWA 50 ppm (245 mg/m3) [skin][3]
IDLH (Immediate danger)
 900 ppm[3]
Related compounds
Related compounds
 ethylbenzene
toluene
benzene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Cumene (isopropylbenzene) is an organic compound that contains a benzene ring with an isopropyl substituent. It is a constituent of crude oil and refined fuels. It is a flammable colorless liquid that has a boiling point of 152 °C. Nearly all the cumene that is produced as a pure compound on an industrial scale is converted to cumene hydroperoxide, which is an intermediate in the synthesis of other industrially important chemicals, primarily phenol and acetone (known as the cumene process).

Production

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Commercial production of cumene is by Friedel–Crafts alkylation of benzene with propylene. The original route for manufacturing of cumene was by alkylation of benzene in the liquid phase using sulfuric acid as a catalyst, but because of the complicated neutralization and recycling steps required, together with corrosion problems, this process has been largely replaced. As an alternative, solid phosphoric acid (SPA) supported on alumina has been used as the catalyst.

Reaction of benzene with propylene to give cumene in the presence of phosphoric acid supported on silica and promoted with boron trifluoride
Reaction of benzene with propylene to give cumene in the presence of phosphoric acid supported on silica and promoted with boron trifluoride

Since the mid-1990s, commercial production has switched to zeolite-based catalysts. In this process, the efficiency of cumene production is generally 70-75%. The remaining components are primarily polyisopropyl benzenes. In 1976, an improved cumene process that uses aluminum chloride as a catalyst was developed. The overall conversion of cumene for this process can be as high as 90%.

The addition of two equivalents of propylene gives diisopropylbenzene (DIPB). Using transalkylation, DIPB is comproportionated with benzene to give cumene.[5]

Autoxidation

[edit]

Depending on the conditions, autoxidation of cumene gives dicumyl peroxide or cumene hydroperoxide. Both reactions exploit the weakness of the tertiary C-H bond. The tendency of cumene to form peroxides by autoxidation poses safety concerns.[6] Tests for peroxides are routinely conducted before heating or distilling.

Applications

[edit]

Cumene is frequently found as an ingredient in thread locking fluids.[7][8] Cumene is also a precursor chemical to the herbicide isoproturon.[9]

See also

[edit]

References

[edit]
  1. ^ Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. 139, 597. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
  2. ^ Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis. 1989.
  3. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0159". National Institute for Occupational Safety and Health (NIOSH).
  4. ^ a b c "Cumene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  5. ^ Bipin V. Vora; Joseph A. Kocal; Paul T. Barger; Robert J. Schmidt; James A. Johnson (2003). "Alkylation". Kirk-Othmer Encyclopedia of Chemical Technology. Kirk‐Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.0112112508011313.a01.pub2. ISBN 0471238961.
  6. ^ CDC - NIOSH Pocket Guide to Chemical Hazards
  7. ^ "LOCTITE 242 MS TL Safety Data Sheet".
  8. ^ "Wurth Blue Thread Locker Safety Data Sheet" (PDF).
  9. ^ Unger, Thomas A. (1996). Pesticide synthesis handbook (1st ed.). Noyes Publications. p. 239.
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