Hydrofluorocarbons (HFCs) are man-made organic compounds that contain fluorine and hydrogen atoms, and are the most common type of
organofluorine compounds. Most are gases at room temperature and pressure. They are frequently used in
air conditioning and as
refrigerants;
R-134a
1,1,1,2-Tetrafluoroethane (also known as norflurane (INN), R-134a, Freon 134a, Forane 134a, Genetron 134a, Green Gas, Florasol 134a, Suva 134a, or HFC-134a) is a hydrofluorocarbon (HFC) and haloalkane refrigerant with thermodynamic properties ...
(1,1,1,2-tetrafluoroethane) is one of the most commonly used HFC
refrigerants. In order to aid the recovery of the stratospheric ozone layer, HFCs were adopted to replace the more potent
chlorofluorocarbons (CFCs), which were phased out from use by the
Montreal Protocol, and
hydrochlorofluorocarbons (HCFCs) which are presently being phased out. HFCs replaced older chlorofluorocarbons such as
R-12 and hydrochlorofluorocarbons such as
R-21.
[
] HFCs are also used in insulating foams, aerosol propellants, as solvents and for fire protection.
They do not harm the ozone layer as much as the compounds they replace, but they do contribute to
global warming
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...
, with trifluoromethane having 11,700 times the warming potential of carbon dioxide. Their atmospheric concentrations and contribution to
anthropogenic greenhouse gas emissions are rapidly increasing, causing international concern about their
radiative forcing.
Chemistry
Fluorocarbons with few C–F
bonds behave similarly to the parent hydrocarbons, but their reactivity can be altered significantly. For example, both
uracil and
5-fluorouracil
Fluorouracil (5-FU), sold under the brand name Adrucil among others, is a cytotoxic chemotherapy medication used to treat cancer. By intravenous injection it is used for treatment of colorectal cancer, oesophageal cancer, stomach cancer, panc ...
are colourless, high-melting crystalline solids, but the latter is a potent anti-cancer drug. The use of the C-F bond in pharmaceuticals is predicated on this altered reactivity.
[G. Siegemund, W. Schwertfeger, A. Feiring, B. Smart, F. Behr, H. Vogel, B. McKusick "Fluorine Compounds, Organic" in "Ullmann's Encyclopedia of Industrial Chemistry" 2005, Wiley-VCH, Weinheim. ] Several drugs and
agrochemicals contain only one fluorine center or one
trifluoromethyl group.
Environmental regulation
Unlike other greenhouse gases in the
Paris Agreement, hydrofluorocarbons are included in other international negotiations.
In September 2016, the
New York Declaration on Forests The New York Declaration on Forests is a voluntary and non-legally binding political declaration which grew out of dialogue among governments, companies and civil society, spurred by the United Nations Secretary-General’s Climate Summit held in ...
urged a global reduction in the use of HFCs.
[
] On 15 October 2016, due to these chemicals' contribution to
climate change, negotiators from 197 nations meeting at a summit of the
United Nations Environment Programme
The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the United Nations Conference on ...
in Kigali, Rwanda reached a legally-binding accord (the
Kigali Amendment) to phase down hydrofluorocarbons (HFCs) in an amendment to the
Montreal Protocol. As of February 2020, 16 U.S. states ban or are phasing down HFCs.
COVID-19
Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was identified in Wuhan, China, in December 2019. The disease quick ...
relief legislation, which included a measure that would require chemical manufacturers to phase down the production and use of HFCs, was passed by the
United States House of Representatives
The United States House of Representatives, often referred to as the House of Representatives, the U.S. House, or simply the House, is the lower chamber of the United States Congress, with the Senate being the upper chamber. Together they ...
and
United States Senate
The United States Senate is the upper chamber of the United States Congress, with the House of Representatives being the lower chamber. Together they compose the national bicameral legislature of the United States.
The composition and po ...
on December 21, 2020. The U.S. Environmental Protection Agency signed a final rule phasing down HFCs on 23 September, 2021.
See also
* - comparative chart
References
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Organofluorides