Cumene

Not to be confused with cumin or cumulene.

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).

Cumene

Names
Preferred IUPAC name (Propan-2-yl)benzene[1]
Other names Isopropylbenzene Cumol (1-Methylethyl)benzene
Identifiers
CAS Number	98-82-8 Y
3D model (JSmol)	Interactive image
Beilstein Reference	1236613
ChEBI	CHEBI:34656 Y
ChEMBL	ChEMBL1398949
ChemSpider	7128 Y
ECHA InfoCard	100.002.458
EC Number	202-704-5
KEGG	C14396 Y
PubChem CID	7406
RTECS number	GR8575000
UNII	8Q54S3XE7K Y
UN number	1918
CompTox Dashboard (EPA)	DTXSID1021827
InChI InChI=1S/C9H12/c1-8(2)9-6-4-3-5-7-9/h3-8H,1-2H3 Y Key: RWGFKTVRMDUZSP-UHFFFAOYSA-N Y InChI=1/C9H12/c1-8(2)9-6-4-3-5-7-9/h3-8H,1-2H3 Key: RWGFKTVRMDUZSP-UHFFFAOYAJ
SMILES CC(C)c1ccccc1
Properties
Chemical formula	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)
Solubility in water	negligible
Solubility	soluble in acetone, ether, ethanol
Vapor pressure	4.5 mmHg (25 °C)[2]
Magnetic susceptibility (χ)	-89.53·10−6 cm3/mol
Refractive index (nD)	1.4915 (20 °C)
Viscosity	0.777 cP (21 °C)
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	flammable
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H226, H302, H304, H312, H314, H332, H335, H341, H412, H441
Precautionary statements	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)	2 3 1
Flash point	43 °C (109 °F; 316 K)
Autoignition temperature	424 °C (795 °F; 697 K)
Explosive limits	0.9-6.5%
Lethal dose or concentration (LD, LC):
LD50 (median dose)	12750 mg/kg (oral, mouse) 1400 mg/kg (oral, rat)[3]
LC50 (median concentration)	200 ppm (mouse, 7 hr)[3]
LCLo (lowest published)	8000 ppm (rat, 4 hr)[3]
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 50 ppm (245 mg/m3) [skin][4]
REL (Recommended)	TWA 50 ppm (245 mg/m3) [skin][4]
IDLH (Immediate danger)	900 ppm[4]
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). Y verify (what is YN ?) Infobox references

Production

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

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

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

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

• Pseudocumene

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. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis. 1989.
3. "Cumene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
4. NIOSH Pocket Guide to Chemical Hazards. "#0159". 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.

External links

• National Pollutant Inventory - Cumene fact sheet
• Cumene Production from Benzene and Propylene Using Aluminum Chloride Catalyst