Cumene

OVERVIEW

Cumene (KYOO-meen) is a colorless, flammable liquid with a penetrating gasoline-like odor. Chemically, it is classified as an aromatic hydrocarbon. Aromatic hydrocarbons are compounds of carbon and hydrogen with a molecular structure based on that of benzene. Although cumene is probably not well known to the average person, it is a very important industrial chemical. In 2004, some 3.74 million metric tons(4.12 million short tons) of cumene were produced in the United States, making it the twentieth most important chemical made in that year by weight. Cumene is used primarily as a raw material in the synthesis of other organic compounds, such as phenol, acetone, acetophenone, and methyl styrene, and as a thinner for paints and lacquers.

KEY FACTS

OTHER NAMES:

Isopropylbenzene;1-(methylethyl) benzene

FORMULA:

C₆H₅CH(CH₃)₂

ELEMENTS:

Carbon, hydrogen

COMPOUND TYPE:

Aromatic hydrocarbon (organic)

STATE:

Liquid

MOLECULAR WEIGHT:

120.19 g/mol

MELTING POINT:

96.02°C ( 140.8°F)

BOILING POINT:

152.41°C (306.34°F)

SOLUBILITY:

Insoluble in water; miscible with ethyl alcohol, benzene, ether, acetone, and most organic solvents

HOW IT IS MADE

Cumene is made in a straight-forward chemical reaction between benzene (C₆H₆) and propene (propylene; CH₃CH=CH₂). It can also be extracted from petroleum or from coal tar, the thick black material left after soft coal is converted to coke.

COMMON USES AND POTENTIAL HAZARDS

Small amounts of cumene are used as thinners for paints, lacquers, and enamels, and as solvents in paints and other types of coatings. By far the greatest amount of cumene, however, is used as a raw material in the manufacture of phenol, acetone, and methyl styrene. These compounds, in turn, have a great many chemical and industrial uses. Some of the most important uses are the production of plastics, such as polystyrene, phenol-formaldehyde resins, and polycarbonates.

Cumene is a skin, eye, and respiratory system irritant. If inhaled, it can cause coughing, dizziness, drowsiness, sore throat, headache, and loss of muscular coordination. In large doses, it has a narcotic effect, resulting in drowsiness and insensitivity to pain and other stimuli, and may lead to unconsciousness. There is no evidence that cumene is carcinogenic or that it causes hereditary damage to a person or to offspring of individuals exposed to the compound.

Interesting Facts

• Traditionally, the synthesis of cumene has involved the use of phosphoric acid (H₃PO₄) as a catalyst. That process results in the release of harmful by-products into the environment, and a new process that uses zeolites as a catalyst has now become more popular. Zeolites are a naturally occurring, earthy material that can be as effective as phosphoric acid in promoting the synthesis of cumene.

Words to Know

AROMATIC HYDROCARBON

A compound of carbon and hydrogen with a molecular structure based on that of benzene.

CATALYST

A material that increases the rate of a chemical reaction without undergoing any change in its own chemical structure.

MISCIBLE

Able to be mixed; especially applies to the mixing of one liquid with another.

SOLVENT

A substance that is able to dissolve one or more other substances.

SYNTHESIS

A chemical reaction in which some desired chemical product is made from simple beginning chemicals, or reactants.

FOR FURTHER INFORMATION

"Cumene." International Programme on Chemical Safety. http://www.inchem.org/documents/cicads/cicads/cicad18.htm#PartNumber:1 (accessed on December 22,2005)

"Cumene." Technology Transfer Network, Air Toxics Website http://www.epa.gov/ttn/atw/hlthef/cumene.html (accessed on December 22, 2005).

"Cumene (1-methylethylbenzene)." Australian Government. Department of the Environment and Heritage. http://www.npi.gov.au/database/substance-info/profiles/28.html (accessed on December 22, 2005).

See Also Acetone; Phenol; Styrene