Trichlorofluoromethane, also called freon-11, CFC-11, or R-11, is a chlorofluorocarbon (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 heat pump and refrigeration cycle, 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. Ref ...

. 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 with ...

, 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 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 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 most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

. 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 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) 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