Trichlorofluoromethane, also called freon-11, CFC-11, or R-11, is a

chlorofluorocarbon Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are fully or partly halogenated hydrocarbons that contain carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F), produced as volatile derivatives of methane, ethane, and p ...

(CFC). It is a colorless, faintly ethereal, and sweetish-smelling liquid that boils around room temperature. CFC-11 is a Class 1 ozone-depleting substance which damages Earth's protective stratospheric ozone layer.

Historical use

Trichlorofluoromethane was first widely used as a

refrigerant A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated ...

. Because of its high boiling point (compared to most refrigerants), it can be used in systems with a low operating pressure, making the mechanical design of such systems less demanding than that of higher-pressure refrigerants R-12 or R-22. Trichlorofluoromethane is used as a reference compound for fluorine-19 NMR studies. Trichlorofluoromethane was formerly used in the drinking bird novelty, largely because it has a boiling point of . The replacement,

dichloromethane Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible wit ...

, boiling point , requires a higher ambient temperature to work. Prior to the knowledge of the ozone depletion potential of chlorine in refrigerants and other possible harmful effects on the environment, trichlorofluoromethane was sometimes used as a cleaning/rinsing agent for low-pressure systems.

Production moratorium

Trichlorofluoromethane was included in the production moratorium agreed in the

Montreal Protocol The Montreal Protocol is an international treaty designed to protect the ozone layer by phasing out the production of numerous substances that are responsible for ozone depletion. It was agreed on 16 September 1987, and entered into force ...

of 1987. It is assigned an ozone depletion potential of 1.0, and U.S. production was ended on January 1, 1996.

Regulatory challenges

In 2018, the atmospheric concentration of CFC-11 was noted by researchers to be declining more slowly than expected, and it subsequently emerged that it remains in widespread use as a

blowing agent A blowing agent is a substance which is capable of producing a cellular structure via a foaming process in a variety of materials that undergo hardening or phase transition, such as polymers, plastics, and metals. They are typically applied wh ...

for polyurethane foam insulation in the construction industry of

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

. In 2021, researchers announced that emissions declined by 20,000 U.S. tons from 2018 to 2019, which mostly reversed the previous spike in emissions. In 2022, the

European Commission The European Commission (EC) is the executive of the European Union (EU). It operates as a cabinet government, with 27 members of the Commission (informally known as "Commissioners") headed by a President. It includes an administrative body ...

announced an updated regulation that mandates the recovery and prevention of emissions of CFC-11 blowing agents from foam insulation in demolition waste, which is still emitted at significant scale from building demolition waste.

Dangers

R11, like most chlorofluoroalkanes, forms phosgene gas when exposed to a naked flame.

Gallery

File:CFC-11 mm.png, CFC-11 measured by the Advanced Global Atmospheric Gases Experiment
AGAGE
in the lower atmosphere (

troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. Fro ...

) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion. File:Hats_f11_global.png , Hemispheric and Global mean concentrations of CFC-11 (NOAA/ESRL) Image:AYool CFC-11 history.png , Time-series of atmospheric concentrations of CFC-11 (Walker ''et al.'', 2000) File:GLODAP sea-surf CFC11 AYool.png , "Present day" (1990s) sea surface CFC-11 concentration File:GLODAP invt CFC11 AYool.png , "Present day" (1990s) CFC-11 oceanic vertical inventory

References

External links

CFC-11 NOAA/ESRL Global measurements

Public health goal for trichlorofluoromethane in drinking water

Names at webbook.nist.gov

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Phase change data at webbook.nist.gov

materialsproject.org
{{fluorine compounds Halomethanes Chlorofluorocarbons Refrigerants Greenhouse gases