Hydrofluorocarbons (HFCs) are man-made organic compounds that contain fluorine and hydrogen atoms, and are the most common type of

organofluorine Organofluorine chemistry describes the chemistry of the organofluorines, organic compounds that contain the carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, ref ...

compounds. Most are gases at room temperature and pressure. They are frequently used in

air conditioning Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...

and as

refrigerants 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 d ...

;

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

. In order to aid the recovery of the stratospheric ozone layer, HFCs were adopted to replace the more potent

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 pro ...

s (CFCs), which were phased out from use by 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 o ...

, and

hydrochlorofluorocarbon 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 pr ...

s (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 E ...

, with trifluoromethane having 11,700 times the warming potential of carbon dioxide. Their atmospheric concentrations and contribution to anthropogenic

greenhouse gas emissions Greenhouse gas emissions from human activities strengthen the greenhouse effect, contributing to climate change. Most is carbon dioxide from burning fossil fuels: coal, oil, and natural gas. The largest emitters include coal in China and ...

are rapidly increasing, causing international concern about their

radiative forcing Radiative forcing (or climate forcing) is the change in energy flux in the atmosphere caused by natural or anthropogenic factors of climate change as measured by watts / metre2. It is a scientific concept used to quantify and compare the extern ...

Chemistry

Fluorocarbons with few C–F bonds behave similarly to the parent hydrocarbons, but their reactivity can be altered significantly. For example, both

uracil Uracil () (symbol U or Ura) is one of the four nucleobases in the nucleic acid RNA. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced b ...

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, pan ...

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 The trifluoromethyl group is a functional group that has the formula -CF3. The naming of is group is derived from the methyl group (which has the formula -CH3), by replacing each hydrogen atom by a fluorine atom. Some common examples are trifluoro ...

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 of the United Nations, Secret ...

urged a global reduction in the use of HFCs. On 15 October 2016, due to these chemicals' contribution to

climate change 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 ...

, 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 th ...

in Kigali, Rwanda reached a legally-binding accord (the

Kigali Amendment The Kigali Amendment to the Montreal Protocol is an international agreement to gradually reduce the consumption and production of hydrofluorocarbons (HFCs). It is a legally binding agreement designed to create rights and obligations in internatio ...

) to phase down hydrofluorocarbons (HFCs) in an amendment to the

. 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 quickly ...

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 pow ...

on December 21, 2020. The U.S. Environmental Protection Agency signed a final rule phasing down HFCs on 23 September, 2021.

References

{{Reflist Organofluorides

Chemistry

Environmental regulation

See also

References