Ethylbenzene

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Ethylbenzene

OVERVIEW

Ethylbenzene (eth-il-BEN-zeen) is a colorless flammable liquid with a pleasant aromatic odor. It is an aromatic hydrocarbon, that is, a compound consisting of carbon and hydrogen only with a molecular structure similar to that of benzene (C₆H₆). In 2004 it ranked fifteenth among chemicals produced in the United States. Its primary use is in the manufacture of another aromatic hydrocarbon, styrene (C₆H₅CH=CH₂), widely used to make a number of polymers, such as polystyrene, styrene-butadiene latex, SBR rubber, and ABS rubber.

KEY FACTS

OTHER NAMES:

Phenylethane; ethylbenzol

FORMULA:

C₆H₅C₂H₅

ELEMENTS:

Carbon, hydrogen

COMPOUND TYPE:

Aromatic hydrocarbon (organic)

STATE:

Liquid

MOLECULAR WEIGHT:

106.16 g/mol

MELTING POINT:

−94.96°C (−138.9°F)

BOILING POINT:

136.19°C (277.14°F)

SOLUBILITY:

Immiscible with water; miscible with ethyl alcohol and methyl alcohol

HOW IT IS MADE

Ethylbenzene occurs to some extent as a component of petroleum. It can be extracted from petroleum by fractional distillation, the process by which individual components of petroleum are separated from each other by heating in a distilling tower. Ethylbenzene can also be made synthetically by reacting benzene with ethene (ethylene; CH₂=CH₂) over a catalyst of aluminum chloride (AlCl₃): C₆H₆ + CH₂=CH₂ → C₆H₅C₂H₅.

COMMON USES AND POTENTIAL HAZARDS

More than 99 percent of the ethylbenzene made is used for a single purpose—the production of styrene. Styrene is a very important industrial chemical, ranking seventeenth among all chemicals produced in the United States in 2004. It is used to make a number of important and popular polymers, the best known of which may be polystyrene. Much smaller amounts of ethylbenzene are used in solvents or as additives to a variety of products. Some products that contain ethylbenzene include synthetic rubber, gasoline and other fuels, paints and varnishes, inks, carpet glues, tobacco products, and insecticides.

The concentration of ethylbenzene in consumer products is so low that it probably poses no threat to human health or to the environment. It may be a problem, however, when it leaks from industrial or chemical plants into the soil and becomes part of the groundwater. In such cases, it may be consumed by humans and other animals, or it may evaporate into the air, where it may be breathed by humans and other animals. Ethylbenzene has been found in about half (731 of 1467) of all the sites surveyed for pollutants by the U.S. Environmental Protection Agency, although concentrations are so low in most cases as to pose no threat to human health or the environment.

Ethylbenzene is an irritant to the skin, eyes, and respiratory system. In small quantities, it may cause dizziness, tightness in the chest, and burning of the eyes. In larger doses, it may cause narcotic effects, producing drowsiness and disorientation. The greatest safety concerns about ethylbenzene relate to its combustibility. Since it is more dense than air, it tends to settle to the ground and travel to any source of fire that may be near by.

Words to Know

CATALYST: A material that increases the rate of a chemical reaction without undergoing any change in its own chemical structure.
IMMISCIBLE: Does not mix with another liquid.
MISCIBLE: Able to be mixed; especially applies to the mixing of one liquid with another.
POLYMER: A compound consisting of very large molecules made of one or two small repeated units called monomers.

FOR FURTHER INFORMATION

"Consumer Factsheet on: Ethylbenzene." U.S. Environmental Protection Agency. http://www.epa.gov/safewater/contaminants/dw_contamfs/ethylben.html (accessed on December 22, 2005).

"Ethylbenzene." Australian Government. Department of the Environment and Heritage. http://www.npi.gov.au/database/substance-info/profiles/40.html (accessed on December 22, 2005).

"ToxFAQs™ for Ethylbenzene." Agency for Toxic Substances and Disease Registry. http://www.atsdr.cdc.gov/tfacts110.html (accessed on December 22, 2005).

Chemical Compounds