Carbon tetrachloride

May 25, 2020
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Readers of a certain age can remember when “carbon tet” was the go-to household solvent that easily removed organic residues such as adhesives and oils from almost any surface. It was also a widely used dry-cleaning solvent, refrigerant, and fire suppressant.

During the 1970s and ’80s, however, toxicologists discovered that inhalation of or skin contact with carbon tetrachloride (CCl4) can damage many organs, including the liver, kidneys, and central nervous system (see hazard table). CCl4 is also a “greenhouse gas” that, according to the 1995 Montreal Protocol, depletes ozone in the Earth’s stratosphere. Consequently, production and use have been significantly reduced.

In its heyday, CCl4 was produced by chlorinating C1 compounds such as chloroform, carbon disulfide, and, in later years, methane. What little is available today is a coproduct from the manufacture of chloroform and dichloromethane; however, US production is still 15 times the amount called for in the Montreal Protocol.

The CCl4 currently produced is used as a feedstock for ozone-safe refrigerants and in some minor agricultural and industrial processes. In a recent draft risk assessment of CCl4 standards under the Toxic Substances Control Act, the US Environmental Protection Agency reports that the compound is safe to use in manufacturing plants if workers wear appropriate personal protective equipment. The assessment is scheduled to be finalized by June.

Carbon tetrachloride hazard information

Hazard class* Hazard statement
Acute toxicity, oral, category 3 H301—Toxic if swallowed Chemical Safety Warning
Acute toxicity, dermal, category 3 H311—Toxic in contact with skin Chemical Safety Warning
Skin sensitisation, category 1B H317—May cause an allergic skin reaction  Chemical Safety Warning
Acute toxicity, inhalation, category 3 H331—Toxic if inhaled Chemical Safety Warning
Carcinogenicity, category 2 H351—Suspected of causing cancer Chemical Safety Warning
Specific target organ toxicity (liver, kidney), repeated exposure, inhalation, category 1  H372—Causes damage to organs (liver, kidney) through prolonged or repeated exposure if inhaled Chemical Safety Warning
Hazardous to the aquatic environment, acute hazard, category 3 H402—Harmful to aquatic life Chemical Safety Warning
Hazardous to the aquatic environment, long-term hazard, category 3 H412—Harmful to aquatic life with long-lasting effects Chemical Safety Warning
Hazardous to the ozone layer, category 1 H420—Harms public health and the environment by destroying ozone in the upper atmosphere Chemical Safety Warning

*Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

Carbon tetrachloride  
fast facts

CAS Reg. No. 56-23-5
Methane, tetrachloro-
Empirical formula CCl4
Molar mass 153.82 g/mol
Appearance Colorless liquid
Boiling point 77 ºC
Water solubility 0.81 g/L

MOTW Update

Vanillin was the Molecule of the Week for September 12, 2016. It is, of course, the major flavor component of vanilla. Most vanillin is made from petrochemical precursors, but now producers are seeking more sustainable sources. Siegfried R. Waldvogel and co-workers at Johannes Gutenberg University Mainz (Germany) report that by using an electrochemical reaction, they can produce vanillin and other useful compounds from lignin, a paper pulp byproduct.

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