Cumene

Cumene (isopropylbenzene) is an organic compound that is based on an aromatic hydrocarbon with an aliphatic substitution. 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.

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
EC Number
  • 202-704-5
KEGG
RTECS number
  • GR8575000
UNII
UN number 1918
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 8 mm (20°C)[2]
-89.53·10−6 cm3/mol
1.4915 (20 °C)
Viscosity 0.777 cP (21 °C)
Hazards
Main hazards flammable
GHS pictograms
GHS Signal word Warning
H226, H302, H304, H312, H314, H332, H335, H341, H412, H441
P201, P202, P260, P261, P264, P270, P271, P273, P280, P281, P301+312, P301+330+331, P302+352, P303+361+353, P304+312, P304+340, P305+351+338, P308+313, P310, P312, P321, P322, P330, P363, P405
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 code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
3
2
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)[3]
200 ppm (mouse, 7 hr)[3]
8000 ppm (rat, 4 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 50 ppm (245 mg/m3) [skin][2]
REL (Recommended)
 TWA 50 ppm (245 mg/m3) [skin][2]
IDLH (Immediate danger)
 900 ppm[2]
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).
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Infobox references

Production

Commercial production of cumene is by Friedel–Crafts alkylation of benzene with propylene. Cumene producers account for approximately 20% of the global demand for benzene.[4] 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 was used as the catalyst.

Reaction of benzene with propene to cumene in the presence of phosphoric acid supported on silica & promoted with boron trifluoride

Since the mid-1990s, commercial production has switched to zeolite-based catalysts.[5] 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.[6]

Safety

Cumene forms peroxides upon long exposure to air.[7] Tests for peroxides are routinely conducted before heating or distilling.

References
  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. NIOSH Pocket Guide to Chemical Hazards. "#0159". National Institute for Occupational Safety and Health (NIOSH).
  3. "Cumene". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  4. Market Study Benzene, published by Ceresana, July 2011
  5. The Innovation Group website, page accessed 15/11/07
  6. 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.CS1 maint: uses authors parameter (link)
  7. CDC - NIOSH Pocket Guide to Chemical Hazards
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