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 prop ...
(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. 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
Fluorine-19 nuclear magnetic resonance spectroscopy (fluorine NMR or 19F NMR) is an analytical technique used to detect and identify fluorine-containing compounds. 19F is an important nucleus for NMR spectroscopy because of its receptivity and ...
studies.
Trichlorofluoromethane was formerly used in the
drinking bird
Drinking birds, also known as insatiable birdies, dunking birds, drinky birds, water birds, dipping birds, and “Sippy Chickens” are toy heat engines that mimic the motions of a bird drinking from a water source. They are sometimes incorrect ...
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 w ...
, 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
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. 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
See also
*
List of refrigerants
This is a list of refrigerants, sorted by their ASHRAE-designated numbers, commonly known as R numbers. Many modern refrigerants are man-made halogenated gases, especially fluorinated gases and chlorinated gases, that are frequently referred to as ...
*
IPCC list of greenhouse gases
This is a list of the most influential long-lived, well-mixed greenhouse gases, along with their tropospheric concentrations and direct radiative forcings, as identified by the Intergovernmental Panel on Climate Change (IPCC). Abundances of thes ...
References
External links
CFC-11 NOAA/ESRL Global measurementsPublic health goal for trichlorofluoromethane in drinking waterNames at webbook.nist.gov*
*
Phase change data at webbook.nist.govmaterialsproject.org
{{fluorine compounds
Halomethanes
Chlorofluorocarbons
Refrigerants
Greenhouse gases