Hydrofluorocarbons(HFCs) are synthetic organic compounds that contain fluorine and hydrogen atoms, and are the most common type oforganofluorinecompounds. Most are gases at room temperature and pressure. They are frequently used inair conditioningand asrefrigerants;R-134a(1,1,1,2-tetrafluoroethane) is one of the most commonly usedHFCrefrigerants.In order to aid the recovery of the stratospheric ozone layer, HFCs were adopted to replace the more potentchlorofluorocarbons(CFCs), which were phased out from use by theMontreal Protocol,andhydrochlorofluorocarbons(HCFCs) which are presently being phased out.[1]HFCs replaced older chlorofluorocarbons such asR-12and hydrochlorofluorocarbons such asR-21.[2]HFCs are also used in insulating foams, aerosol propellants, as solvents and for fire protection.
They may not harm the ozone layer as much as the compounds they replace, but they still contribute toglobal warming--- with some like trifluoromethane having 11,700 times the warming potential of carbon dioxide.[3]Their atmospheric concentrations and contribution toanthropogenicgreenhouse gas emissionsare rapidly increasing --- consumption rose from near zero in 1990 to 1.2 billion tons of carbon dioxide equivalent in 2010[4]--- causing international concern about theirradiative forcing.
Chemistry
editFluorocarbons with fewC–Fbondsbehave similarly to the parenthydrocarbons,but their reactivity can be altered significantly. For example, bothuraciland5-fluorouracilare 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.[5]Several drugs andagrochemicalscontain only one fluorine center or onetrifluoromethylgroup.
Environmental regulation
editUnlike other greenhouse gases in theParis Agreement,hydrofluorocarbons are included in other international negotiations.[6]
In September 2016, theNew York Declaration on Forestsurged a global reduction in the use of HFCs.[7]On 15 October 2016, due to these chemicals' contribution toclimate change,negotiators from 197 nations meeting at a summit of theUnited Nations Environment Programmein Kigali, Rwanda reached a legally-binding accord (theKigali Amendment) to phase down hydrofluorocarbons (HFCs) in an amendment to theMontreal Protocol.[8][9][10]As of February 2020, 16 U.S. states ban or are phasing down HFCs.[11]
COVID-19relief legislation, which included a measure that would require chemical manufacturers to phase down the production and use of HFCs, was passed by theUnited States House of RepresentativesandUnited States Senateon December 21, 2020.[12]The U.S. Environmental Protection Agency signed a final rule phasing down HFCs on 23 September 2021.[13]
See also
edit- Greenhouse gas § Sources- comparative chart
References
edit
- ^Zaelke, Durwood; Borgford-Parnell, Nathan; Andersen., Stephen (11 January 2018)."Primer on HFCs"(PDF).Kristin Campbell, Xiaopu Sun, Dennis Clare, Claire Phillips, Stela Herschmann, Yuzhe PengLing, Alex Milgroom, Nancy J. Sherman. Institute for Governance & Sustainable Development (IGSD): 5.
{{cite journal}}:Cite journal requires|journal=(help) - ^ Milman, Oliver (22 September 2016)."100 countries push to phase out potentially disastrous greenhouse gas".The Guardian.London, UK.Retrieved22 September2016.
- ^Han, Wenfeng; Li, Ying; Tang, Haodong; Liu, Huazhang (2012)."Treatment of the potent greenhouse gas, CHF3—An overview".Journal of Fluorine Chemistry.140:7–16.doi:10.1016/j.jfluchem.2012.04.012.
- ^Toit, Louise du (2023-12-01),"Strengthening the Global Regulation of Hydrofluorocarbons under the Montreal Protocol",Reducing Emissions of Short-Lived Climate Pollutants,Brill Nijhoff, pp.90–124,doi:10.1163/9789004684089_006,ISBN978-90-04-68408-9,retrieved2024-04-30
- ^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.doi:10.1002/14356007.a11_349
- ^Davenport, Carol (23 July 2016)."A Sequel to the Paris Climate Accord Takes Shape in Vienna".New York Times.Retrieved17 August2016.
- ^ "The New York Declaration of the Coalition to Secure an Ambitious HFC Amendment".Washington, DC: US Department of State. 22 September 2016.Retrieved22 September2016.
- ^Johnston, Chris; Milman, Oliver; Vidal, John (15 October 2016)."Climate change: global deal reached to limit use of hydrofluorocarbons".The Guardian.Retrieved15 October2016.
- ^"Climate change: 'Monumental' deal to cut HFCs, fastest growing greenhouse gases".BBC News. 15 October 2016.Retrieved15 October2016.
- ^"Nations, Fighting Powerful Refrigerant That Warms Planet, Reach Landmark Deal".New York Times.15 October 2016.Retrieved15 October2016.
- ^Baker Administration Planning Rule To Ban Hydrofluorocarbons
- ^Davenport, Coral (2020-12-22)."Congress included climate change legislation in its coronavirus relief deal".The New York Times.ISSN0362-4331.Retrieved2020-12-22.
- ^Volcovici, Valerie (2021-09-23)."Biden administration takes aim at climate warming gas".Yahoo! News.Retrieved2021-09-23.