fluoroform

About 20 million kg per year are produced industrially as both a by-product of and precursor to the manufacture of Teflon. It is produced by reaction of chloroform with HF:{{Ullmann|author=G. Siegemund|author2=W. Schwertfeger|author3=A. Feiring|author4= B. Smart|author5=F. Behr|author6= H. Vogel|author7=B. McKusick|title=Fluorine Compounds, Organic|year=2005|doi=10.1002/14356007.a11_349}}

:{{chem2|CHCl3 + 3 HF → CHF3 + 3 HCl}}

It is also generated biologically in small amounts apparently by decarboxylation of trifluoroacetic acid.Kirschner, E., Chemical and Engineering News 1994, 8.

Fluoroform was first obtained by Maurice Meslans in the violent reaction of iodoform with dry silver fluoride in 1894.{{cite journal|title = Recherches sur quelques fluorures organiques de la série grasse|author = Meslans M. M.

|journal = Annales de chimie et de physique|year = 1894|volume = 7|issue = 1|pages = 346–423|url = http://gallica.bnf.fr/ark:/12148/bpt6k34901c/f344.table}} The reaction was improved by Otto Ruff by substitution of silver fluoride by a mixture of mercury fluoride and calcium fluoride.{{cite journal|title = Fluoroform|author = Henne A. L.|journal = Journal of the American Chemical Society|year = 1937|volume = 59|issue = 7|pages = 1200–1202|doi = 10.1021/ja01286a012}} The exchange reaction works with iodoform and bromoform, and the exchange of the first two halogen atoms by fluorine is vigorous. By changing to a two step process, first forming a bromodifluoromethane in the reaction of antimony trifluoride with bromoform and finishing the reaction with mercury fluoride the first efficient synthesis method was found by Henne.

{{chem2|CHF3}} is used in the semiconductor industry in plasma etching of silicon oxide and silicon nitride. Known as R-23 or HFC-23, it was also a useful refrigerant, sometimes as a replacement for chlorotrifluoromethane (CFC-13) and is a byproduct of its manufacture.

When used as a fire suppressant, the fluoroform carries the DuPont trade name, FE-13. {{chem2|CHF3}} is recommended for this application because of its low toxicity, its low reactivity, and its high density. HFC-23 has been used in the past as a replacement for Halon 1301(CFC-13B1) in fire suppression systems as a total flooding gaseous fire suppression agent.

Fluoroform is weakly acidic with a pK_a = 25–28 and quite inert. Attempted deprotonation results in defluorination to generate {{chem2|F−}} and difluorocarbene ({{chem2|CF2}}). Some organocopper and organocadmium compounds have been developed as trifluoromethylation reagents.{{Cite journal|last1=Zanardi|first1=Alessandro|last2=Novikov|first2=Maxim A.|last3=Martin|first3=Eddy|last4=Benet-Buchholz|first4=Jordi|last5=Grushin|first5=Vladimir V.|date=2011-12-28|title=Direct Cupration of Fluoroform|journal=Journal of the American Chemical Society|volume=133|issue=51|pages=20901–20913|doi=10.1021/ja2081026|pmid=22136628|issn=0002-7863}}

Fluoroform is a precursor of the Ruppert-Prakash reagent Trifluoromethyltrimethylsilane, which is a source of the nucleophilic {{chem2|CF3−}} anion.Rozen, S.; Hagooly, A. "Fluoroform" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. {{doi| 10.1002/047084289X.rn00522}}{{Cite journal|last1=Prakash|first1=G. K. Surya|last2=Jog|first2=Parag V.|last3=Batamack|first3=Patrice T. D.|last4=Olah|first4=George A.|date=2012-12-07|title=Taming of Fluoroform: Direct Nucleophilic Trifluoromethylation of Si, B, S, and C Centers|journal=Science|language=en|volume=338|issue=6112|pages=1324–1327|doi=10.1126/science.1227859|issn=0036-8075|pmid=23224551|bibcode=2012Sci...338.1324P|s2cid=206544170}}

File:HFC-23_mm.png) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion.]]

File:Halogenated gas concentrations 1978-present.png

{{chem2|CHF3}} is a potent greenhouse gas. A ton of HFC-23 in the atmosphere has the same effect as 11,700 tons of carbon dioxide. This equivalency, also called a 100-yr global warming potential, is slightly larger at 14,800 for HFC-23.{{cite conference|title = Changes in Atmospheric Constituents and in Radiative Forcing.|book-title = Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change|url = http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf|author = Forster, P.|author2 = V. Ramaswamy|author3 = P. Artaxo|author4 = T. Berntsen|author5 = R. Betts|author6 = D.W. Fahey|author7 = J. Haywood|author8 = J. Lean|author9 = D.C. Lowe|author10 = G. Myhre|author11 = J. Nganga|author12 = R. Prinn|author13 = G. Raga|author14 = M. Schulz|author15 = R. Van Dorland|name-list-style = amp|date = 2007 }}

The atmospheric lifetime is 270 years.

HFC-23 was the most abundant HFC in the global atmosphere until around 2001, when the global mean concentration of HFC-134a (1,1,1,2-tetrafluoroethane), the chemical now used extensively in automobile air conditioners, surpassed those of HFC-23. Global emissions of HFC-23 have in the past been dominated by the inadvertent production and release during the manufacture of the refrigerant HCFC-22 (chlorodifluoromethane).

Substantial decreases in HFC-23 emissions by developed countries were reported from the 1990s to the 2000s: from 6-8 Gg/yr in the 1990s to 2.8 Gg/yr in 2007.{{cite journal |doi=10.1029/2009GL041195|title=Recent increases in global HFC-23 emissions|year=2010|last1=Montzka|first1=S. A.|last2=Kuijpers|first2=L.|last3=Battle|first3=M. O.|last4=Aydin|first4=M.|last5=Verhulst|first5=K. R.|last6=Saltzman|first6=E. S.|last7=Fahey|first7=D. W.|journal=Geophysical Research Letters|volume=37|issue=2|pages=n/a|bibcode=2010GeoRL..37.2808M|s2cid=13583576 |url=https://escholarship.org/uc/item/3f31077f}}

However, research in 2024 strongly indicates that the HFC-23 emission decrease is much less than has been reported and does not meet the internationaly agreed Kigali Amendment of 2020.{{Cite web |last=Cuff |first=Madeleine |date=3 Jan 2025 |title=Global treaty is failing to curb ultra-potent greenhouse gas emissions |url=https://www.newscientist.com/article/2462478-global-treaty-is-failing-to-curb-ultra-potent-greenhouse-gas-emissions/ |access-date=2025-01-03 |website=New Scientist |language=en-US}}{{Cite journal |last=Adam |first=Ben |last2=Western |first2=Luke M. |last3=Mühle |first3=Jens |last4=Choi |first4=Haklim |last5=Krummel |first5=Paul B. |last6=O’Doherty |first6=Simon |last7=Young |first7=Dickon |last8=Stanley |first8=Kieran M. |last9=Fraser |first9=Paul J. |last10=Harth |first10=Christina M. |last11=Salameh |first11=Peter K. |last12=Weiss |first12=Ray F. |last13=Prinn |first13=Ronald G. |last14=Kim |first14=Jooil |last15=Park |first15=Hyeri |date=2024-12-21 |title=Emissions of HFC-23 do not reflect commitments made under the Kigali Amendment |url=https://www.nature.com/articles/s43247-024-01946-y |journal=Communications Earth & Environment |language=en |volume=5 |issue=1 |pages=1–8 |doi=10.1038/s43247-024-01946-y |issn=2662-4435|pmc=11663144 }}

The UNFCCC Clean Development Mechanism provided funding and facilitated the destruction of HFC-23.

Developing countries have become the largest producers of HCFC-23 in recent years according to data compiled by the Ozone Secretariat of the World Meteorological Organization.{{Cite web |url=http://ozone.unep.org/Data_Reporting/Data_Access/ |title=Data Access Centre |access-date=2010-04-03 |archive-url=https://web.archive.org/web/20110721233408/http://ozone.unep.org/Data_Reporting/Data_Access/ |archive-date=2011-07-21 |url-status=dead }}[https://www.nytimes.com/2012/08/09/world/asia/incentive-to-slow-climate-change-drives-output-of-harmful-gases.html Profits on Carbon Credits Drive Output of a Harmful Gas] August 8, 2012 New York Times[https://www.nytimes.com/interactive/2012/08/09/world/subsidies-for-a-global-warming-gas.html Subsidies for a Global Warming Gas] Emissions of all HFCs are included in the UNFCCCs Kyoto Protocol. To mitigate its impact, {{chem2|CHF3}} can be destroyed with electric plasma arc technologies or by high temperature incineration.{{cite journal|author=Han, Wenfeng|author2=Li, Ying|author3=Tang, Haodong|author4=Liu, Huazhang

|journal=Journal of Fluorine Chemistry|title=Treatment of the potent greenhouse gas, CHF₃. An overview|year=2012|volume=140|pages=7–16|doi=10.1016/j.jfluchem.2012.04.012}}

{{Reflist}}

• {{cite journal|title = Fluorine Chemistry|author = McBee E. T.|journal = Industrial & Engineering Chemistry|year = 1947|volume = 39|issue = 3|pages = 236–237|doi = 10.1021/ie50447a002}}
• {{cite journal|title = Growth of fluoroform (CHF₃, HFC-23) in the background atmosphere|author1 = Oram D. E.|author2 = Sturges W. T.|author3 = Penkett S. A.|author4 = McCulloch A.|author5 = Fraser P. J.|journal = Geophysical Research Letters|year = 1998|volume = 25|issue = 1|pages = 236–237|doi = 10.1029/97GL03483|bibcode = 1998GeoRL..25...35O|doi-access = free}}
• {{cite journal|title = Fluorocarbons in the global environment: a review of the important interactions with atmospheric chemistry and physics|author = McCulloch A.|journal = Journal of Fluorine Chemistry|year = 2003|volume = 123|issue = 1|pages = 21–29|doi = 10.1016/S0022-1139(03)00105-2}}

• {{ICSC|0577|05}}
• [https://web.archive.org/web/20071011165927/http://ptcl.chem.ox.ac.uk/MSDS/TR/trifluoromethane.html MSDS at Oxford University]
• [https://web.archive.org/web/20061015041042/https://www.mathesontrigas.com/pdfs/msds/MAT09970.pdf MSDS at mathesontrigas.com]
• [http://rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=a801406j&JournalCode=CC Coupling of fluoroform with aldehydes using an electrogenerated base]

{{Halomethanes}}

{{fluorine compounds}}

Category:Fluoroalkanes

Category:Halomethanes

Category:Refrigerants

Category:Fire suppression agents

Category:Greenhouse gases

Category:Trifluoromethyl compounds

Category:Hydrofluorocarbons