Ethylene Glycol
Overview
Ethylene glycol (ETH-uh-leen GLYE-kol) is clear, colorless, syrupy liquid with a sweet taste. One should not attempt to confirm the compound's taste, however, as it is toxic. In recent years, more than 4 billion kilograms (9 billion pounds) of ethylene glycol has been produced in the United States annually. The compound is used primarily as an antifreeze and in the manufacture of a number of important chemical compounds, including polyester fibers, films, bottles, resins, and other materials.
Key Facts
Other Names:
Ethylene alcohol; monoethylene glycol
Formula:
CH2OHCH2OH
Elements:
Carbon, hydrogen, oxygen
Compound Type:
Dihydric alcohol (organic)
State:
Liquid
Molecular Weight:
62.07 g/mol
Melting Point:
−12.69°C (9.16°F)
Boiling Point:
197.3°C (387.1°F)
Solubility:
Miscible with water, alcohol, acetone, and ether
Ethylene glycol was first prepared in 1859 by the French chemist Charles Adolphe Wurtz (1817–1884). Wurtz's discovery did not find an application, however, until the early twentieth century, when the compound was manufactured for use in World War I (1914–1918) in the manufacture of explosives and as a coolant. By the 1930s, a number of uses for the compound had been found, and the chemical industry began producing ethylene glycol in large quantities.
How It Is Made
The primary method of producing ethylene glycol involves the hydration of ethylene oxide, a ring compound consisting of two methylene (-CH2) groups and one oxygen atom. Hydration is the process by which water is added to a compound. The hydration of ethylene oxide is conducted at a temperature of about 383°F (195°C) without a catalyst, or at about 50°C to 70°C (122°F to 158°F) with a catalyst, usually a strong acid, either process resulting in a yield of at least 90 percent of ethylene glycol.
Other methods of preparation are also available. For example, the compound can be produced directly from synthesis gas, a mixture of carbon monoxide and hydrogen; or by treating ethylene (CH2=CH2) with oxygen in an acetic acid solution using a catalyst of tellurium oxide or bromide ion.
Common Uses and Potential Hazards
One of the first major uses of ethylene glycol was as a radiator coolant in airplanes. The compound actually made possible a change in the design of airplanes. At one time, plain water was used as the coolant in airplane radiators. The faster the airplane flew, the greater the risk that its radiator would boil over. Adding ethylene glycol to the water raised the boiling point of the coolant and allowed airplanes to fly faster with smaller radiators. This change was especially useful in the construction of military airplanes used in combat.
Ethylene glycol is still used extensively as a coolant and antifreeze in cooling systems. It is also used as a deicing fluid for airport runways, cars, and boats. Brake fluids and shock-absorber fluids often contain ethylene glycol as protection against freezing. About 26 percent of all the ethylene glycol made in the United States is used for some kind of cooling or antifreeze application.
Interesting Facts
- In 1996, 60 children died in Haiti of ethylene glycol poisoning after drinking cough syrup made in China that had accidentally been contaminated with the compound.
The largest single use of ethylene glycol today is in the manufacture of a plastic called polyethylene terephthalate (PET). PET's primary application is in the manufacture of plastic bottles, an application that accounts for about a third of all the ethylene glycol made in the United States. Large amounts of PET are also used in the manufacture of polyester fibers and films. Some additional uses of the compound include:
- As a humectant (a substance that attracts moisture) in keeping some food, tobacco, and industrial products dry;
- As a solvent in some paints and plastics;
- In the dyeing of leathers and textiles;
- In the manufacture of printing inks, wood stains, ink for ball-point pens, and adhesives;
- In the production of artificial smoke and fog for theatrical productions;
- As a stabilizer in the soybean-based foam sometimes used to extinguish industrial fires; and
- In the manufacture of specialized types of explosives.
Ethylene glycol poses a number of potential health and safety hazards. It is very flammable and highly toxic. Ingestion of the compound may cause nausea, vomiting, abdominal pain, weakness, convulsions, and cardiac problems. Higher doses can result in severe kidney damage that leads to death.
Words to Know
A material that increases the rate of a chemical reaction without undergoing any change in its own chemical structure. A substance that attracts moisture more easily than other substances. able to be mixed; especially applies to the mixing of one liquid with another.For Further Information
"Ethylene Glycol." Environmental Protection Agency. http://www.epa.gov/ttn/atw/hlthef/ethy-gly.html (accessed on October 7, 2005).
"Ethylene Glycol." National Safety Council. http://www.nsc.org/library/chemical/Ethylen1.htm (accessed on October 7, 2005).
"Medical Management Guidelines (MMGs) for Ethylene Glycol." Agency for Toxic Substances and Disease Registry. http://www.atsdr.cdc.gov/MHMI/mmg96.html (accessed on October 7, 2005).
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