1,3-Butadiene

OVERVIEW

1,3-butadiene (one-three-byoo-tah-DYE-een) is a colorless gas with a mild, slightly sweet odor. It occurs naturally in petroleum, from which it is extracted at refineries. The compound was first discovered in petroleum in 1886 by the English chemist Henry E. Armstrong (1848–1937) and his colleague A. K. Miller (no dates available). This discovery apparently had no practical application until 1910 when the Russian chemist Sergei Lebedev (1874–1934) developed a method for polymerizing butadiene to make a rubber-like substance. Even then, Lebedev's invention, called polybutadiene, was primarily a laboratory curiosity. There was relatively little demand for rubber products that could not be met by the vast supplies of natural rubber from Southeast Asia.

KEY FACTS

OTHER NAMES:

Biethylene; bivinyl; divinyl; erythrene; vinylethylene

FORMULA:

CH₂=CHCH=CH₂

ELEMENTS:

Carbon, hydrogen

COMPOUND TYPE:

Alkene (unsaturated hydrocarbon)

STATE:

Gas

MOLECULAR WEIGHT:

54.09 g/mol

MELTING POINT:

−108.91°C (−164.04°F)

BOILING POINT:

−4.41°C (−24.1°F)

SOLUBILITY:

Insoluble in water; soluble in alcohol, ether, and benzene

That situation began to change in the 1920s and 1930s. The demand for rubber products in automobiles and other motor vehicles, especially tires, grew rapidly as car and truck production increased rapidly year after year. At the same time, manufacturers began to worry about losing their supply of natural rubber from traditional suppliers in Java, Malaysia, Sumatra, and other parts of Asia. As a result, chemists in Europe and the United States began to look for synthetic substitutes for natural rubber. Lebedev's discovery provided one solution to this problem, and butadiene-based synthetic rubber products were soon flowing from manufacturing plants.

HOW IT IS MADE

Butadiene is made by three processes in the United States. The first two of those processes begin with four-carbon compounds called butane (CH₃CH₂CH₂CH₃) and butene (CH₂=CHCH₂CH₃ and CH₃CH=CHCH₃). These compounds are treated in one of two ways so as to add one more double bond to the molecules, resulting in the formation of 1,3-butadiene (CH₂=CHCH=CH₂). The third and most common process is known as steam cracking. Steam cracking is a process by which large petroleum molecules are exposed to very hot steam, causing them to break apart into smaller molecules. Steam cracking is the method by which ethylene, the most important organic chemical produced in the United States, is made. 1,3-butadiene is a by-product of this process, and is separated from the major product, ethylene, after cracking is complete.

COMMON USES AND POTENTIAL HAZARDS

Virtually all of the 1,3-butadiene produced is used in the manufacture of polymers. Polybutadiene itself is too soft for most industrial rubber uses. So it is sometimes mixed with other polymers to make products with a variety of desirable qualities. Or it is polymerized with other monomers to make specialized copolymers. One of the most popular of the mixed polymers is polystyrene-polybutadiene. The second polymer in this mixture, polystyrene, is a polymer of the compound styrene (C₆H₅CH=CH₂). Some other uses of 1,3-butadiene include:

• Raw material in the manufacture of fungicides such as Captan and Captofol;
• Manufacture of latex adhesives;
• Production of domestic products, such as the backing on nylon carpet, appliance and electrical equipment, and luggage;
• Manufacture of industrial products, such as piping and conduits.

Interesting Facts

• In 2004, U.S. manufacturers produced 2.2 million metric tons (2.4 million short tons) of 1,3-butadiene, ranking it number 22 among all chemicals produced in the United States.

1,3-butadiene has a variety of harmful effects on humans, including irritation of the respiratory system, fatigue, drowsiness, headache, vertigo, loss of consciousness, respiratory paralysis, and death. The compound is also thought to be a carcinogen. Only people who work directly with the compound, however, are likely to experience such effects, and only then in unusual situations. The average person is likely to have no contact with the compound.

Words to Know

CARCINOGEN

A substance that causes cancer in humans or other animals.

COPOLYMER

A polymer made with two different monomers.

POLYMER

A compound consisting of very large molecules made of one or two small repeated units called monomers.

POLYMERIZING

The process by which polymers are made.

FOR FURTHER INFORMATION

"1,3-Butadiene." National Safety Council. http://www.nsc.org/library/chemical/13-Butad.htm (accessed September 14, 2005).

"1,3-Butadiene Health Effects." Occupational Safety &Health Administration. http://www.osha.gov/SLTC/butadiene/healtheffects.html (accessed September 14, 2005).

Johnson, Peter S. Rubber Processing: An Introduction. Cincinatti, OH: Hanser Gardner Publications, 2001.

"ToxFAQs for 1,3-Butadiene." Agency for Toxic Substances and Disease Registry. http://www.atsdr.cdc.gov/tfacts28.html (accessed September 14, 2005).

See AlsoStyrene