Freon

• DEFINITION: A nontoxic, nonflammable refrigerant gas
• Freon and other chlorofluorocarbons served a number of purposes in many industries, but it was found that they were harmful to the Earth’s ozone layer, and nations around the world united in banning their use.

Freon is the DuPont Corporation’s trade name for a compound used as a refrigerant. Freon, which was introduced in 1930, is an example of a class of gases known as chlorofluorocarbons (CFCs), carbon compounds that contain fluorine and chlorine. They are derivatives of simple alkanes—such as methane, ethane, propane, and butane—through direct or selective ultraviolet halogenation using chlorine or fluorine gas.

Freon found extensive uses in industry. CFCs have served as dispersing gases in aerosol cans, in the preparation of foamed plastics, and, primarily, as refrigerants. Their manufacture, together with that of the closely related halons, rose in the mid-1970s and peaked in 1986, with production reaching almost 1.25 million tons. At that time, these compounds were universally used in aerosol products ranging from insecticides to shaving foams and hair sprays, as well as in the insulation of buildings and as cleaning solutions for circuit boards and other electronic parts. One of them, bromotrifluoromethane (Freon 13B1), was used as a fire extinguisher in situations where the use of water had to be avoided, such as electrical fires.

Common members of this family of chemicals include trichlorofluoromethane (Freon or CFC 11), dichlorodifluoromethane (CFC 12), and 1,2-dichloro 1,1,2,2-tetrafluoroethane (CFC 114). They are all either gases or low-boiling liquids at room temperature and are virtually insoluble in water. They are generally dense, easily liquefied, not flammable, thermally stable, virtually odorless, and inexpensive to manufacture. They do not undergo decomposition via the ordinary chemical reactions that take place in the troposphere. As a result, they were seen as ideal for use as propellants in aerosol cans of deodorants, hair sprays, and various commercially available food products. Their relative inertness toward other chemicals allows them also to persist in the atmosphere, causing environmental problems.

Because they are water-insoluble, rain cannot dissolve them and wash them down to the ground. As a result, they drift upward into the stratosphere and the ozone layer, which they reach after approximately seven to ten days. They may stay in the stratosphere for several decades, absorb the sun’s ultraviolet light, and yield free radicals, which appear to undergo chemical reactions that lead to the depletion of the ozone layer. Although ozone is toxic to human lungs, its presence in the stratosphere is critical in protecting the Earth from the harmful ultraviolet part of the electromagnetic radiation associated with sunlight. If the ozone layer gets thin, exposure to ultraviolet radiation will exponentially increase the cases of skin cancer and other diseases, while at the same time destroying crops and other plants.

CFCs have been found to escape into the atmosphere from old refrigerators and air-conditioning units. Most industrialized countries have banned their use and have replaced them with methylene chloride or nonhalogenated hydrocarbons, such as isobutane. The flammability of those hydrocarbons and the suspected carcinogenicity of methylene chloride have created an incentive for the development of CFC substitutes. In 1970, the US Congress passed legislation aimed at curbing the sources of air pollution by setting standards for air quality. In 1987, more than twenty nations signed the Montreal Protocol, an agreement to downscale production of CFCs, with the intent of eventually eradicating their use. By 2009, all members of the United Nations had ratified the protocol. The agreement called for the complete phasing out of freon as a refrigerant in all products by January 1, 2020. That goal was met in the United States, but some air conditioning products made before 2015 may still contain freon. Since 2015, a refrigerant called puron (R-410A) became the industry standard, but after further research, scientists discovered that this, too, may contribute to climate change. Under the American Innovation and Manufacturing (AIM) Act, newly installed residential and small commercial air conditioning units could not use puron beginning January 2025. Sustainable alternatives became the new industry standard, including R-32 and R-454B.

Bibliography

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Dauvergne, Peter. “Refrigerating the Ozone Layer.” The Shadows of Consumption: Consequences for the Global Environment. MIT Press, 2008.

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Joesten, Melvin D., et al. “Chlorofluorocarbons and the Ozone Layer.” The World of Chemistry: Essentials. 4th ed., Thomson Brooks/Cole, 2007.

Parson, Edward A. Protecting the Ozone Layer: Science and Strategy. Oxford UP, 2003.