What Is Carbon Tetrachloride?

After completing this section, you will be able to describe carbon tetrachloride (CCl₄).

Carbon tetrachloride (CCl₄) is a manufactured chemical that does not occur naturally in the environment. Its chemical structure is shown below:

Figure 1. Carbon tetrachloride chemical structure

CCl₄ is a clear, nonflammable, heavy liquid that evaporates readily, producing a sweet characteristic odor similar to chloroform.

CCl₄ is classified as a volatile organic compound (VOC).

Although CCl₄ does not occur naturally, it is ubiquitous as a result of industrial uses. It is a stable compound, with a half-life of 6-12 months in water or soil and a half-life of 30-100 years in the atmosphere.

Common synonyms for carbon tetrachloride include

• Carbon tet,
• Freon 10,
• Perchloromethane,
• Tetrachloromethane. A more detailed list of synonyms is available from: https://chem.nlm.nih.gov/chemidplus/name/carbon%20tetrachloride%20%5Bnf%5D.

Historically, CCl₄ was mainly used to produce chlorofluorocarbons (CFCs), which are used as heat transfer agents in refrigerating equipment and as aerosol propellants [Holbrook 1991]. In the United States, CCl₄ was also an ingredient in many industrial fluids, and was an effective metal degreaser. It was found in household cleaning supplies and spot removers for carpets, clothing, and furniture [Doherty 2000; Odabasi 2008]. CCl₄ was also used as an antihelminthic, a grain fumigant, and a component in fire extinguishers.

Carbon tetrachloride’s toxicity was recognized in the early 1900s [Abbott and Miller 1948; Hardin 1954], and most of the uses were discontinued by the mid-1960s. The U.S. Environmental Protection Agency cancelled CCl₄‘s use as a fumigant in 1986. In the United States, CCl₄ use is restricted to industrial and laboratory applications only [Seifert 1994; ATSDR 2005; NTP 2016]. It is not permitted in products intended for home use; however, chemicals containing CCl₄ can still be purchased online [EPA 2017].

Both the internationally ratified Montreal Protocol (which first went into effect in 1989) and the United States 1990 Clean Air Act Amendments were instrumental in reducing environmental concentrations of CCl₄ and other ozone-depleting chemicals [ATSDR 2005]. By 2009, the United States no longer regularly imported CCl₄; only 90 pounds (41 kilograms) were imported during 1996-2009. Likewise, U.S. production and export of CCl₄ dropped precipitously during this time [NTP 2016]. By 2009, only 26 manufacturers worldwide produced carbon tetrachloride, including three in the United States [NTP 2016].

• Most industrial CCl₄ is used in the synthesis of CFCs and chlorinated solvents. Production of CCl₄ has been continuously declining in response to regulation.
• Because of CCl₄‘s toxicity, use in consumer products, and as a fumigant it is no longer permitted in the United States; only industrial uses and laboratory applications remain.