Fluoroform

{{Redirect|CHF3|the Transport Canada LID|Westlock (Hnatko Farms) Aerodrome}} {{Chembox | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 461102015 | ImageFileL1 = Fluoroform.svg | ImageClassL1 = skin-invert-image | ImageFileR1 = Fluoroform-3D-vdW.png | ImageClassR1 = bg-transparent | IUPACName = Trifluoromethane | OtherNames = Fluoroform, carbon trifluoride,{{citation needed|date=August 2023}} methyl trifluoride, Fluoryl, Freon 23, Arcton 1 |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | Abbreviations = HFC 23, R-23, FE-13, UN 1984 | ChemSpiderID = 21106179 | InChIKey = XPDWGBQVDMORPB-UHFFFAOYAM | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/CHF3/c2-1(3)4/h1H | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = XPDWGBQVDMORPB-UHFFFAOYSA-N | CASNo = 75-46-7 | CASNo_Ref = {{cascite|correct|CAS}} | EINECS = 200-872-4 | PubChem = 6373 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = ZJ51L9A260 | SMILES = FC(F)F | InChI = 1/CHF3/c2-1(3)4/h1H | RTECS = PB6900000 | ChEBI_Ref = {{ebicite|changed|EBI}} | ChEBI = 24073 }} |Section2={{Chembox Properties | C=1|H=1|F=3 | Appearance = Colorless gas | MeltingPtC = −155.2 | BoilingPtC = −82.1 | Solubility = 1 g/L | SolubleOther = Soluble | Solvent = organic solvents | VaporPressure = 4.38 MPa at 20 °C | HenryConstant = 0.013 mol·kg−1·bar−1 | pKa = 25–28 | Density = 2.946 kg/m3 (gas, 1 bar, 15 °C) }} |Section3={{Chembox Structure | CrystalStruct = | Coordination = | MolShape = Tetrahedral }} |Section7={{Chembox Hazards | MainHazards = Nervous system depression | GHSPictograms = {{GHS04}} | GHSSignalWord = Warning | HPhrases = {{HPhrases|H280}} | PPhrases = {{PPhrases|P403}} | GHS_ref = <ref>GHS: [https://gestis.dguv.de/data?name=038260 GESTIS 038260]</ref> | NFPA-H = 2 | NFPA-F = 0 | NFPA-R = 0 | NFPA-S = | FlashPt = Non-flammable | AutoignitionPt = }} |Section9 = {{Chembox Related |OtherFunction_label = chloromethanes |OtherCompounds = {{ubl|Fluoromethane {{chem2|CH3F}}|Difluoromethane {{chem2|CH2F2}}|Tetrafluoromethane {{chem2|CF4}}|Chloroform {{chem2|CHCl3}}|Bromoform {{chem2|CHBr3}}|Iodoform {{chem2|CHI3}}|Chlorodifluoromethane {{chem2|CHF2Cl}}|Dichlorofluoromethane {{chem2|CHFCl2}}|Bromodichloromethane {{chem2|CHCl2Br}}|Dibromochloromethane {{chem2|CHClBr2}}|Bromodifluoromethane {{chem2|CHF2Br}}|Dibromofluoromethane {{chem2|CHFBr2}}|Deuterated chloroform {{chem2|CDCl3}}}} }} }}

'''Fluoroform''', or '''trifluoromethane''', is the chemical compound with the formula {{chem2|CHF3}}. It is a hydrofluorocarbon as well as being a part of the haloforms, a class of compounds with the formula {{chem2|CHX3}} (X = halogen) with C3v symmetry. Fluoroform is used in diverse applications in organic synthesis. It is not an ozone depleter but is a greenhouse gas.<ref name=SynLett>{{cite journal|journal=Synlett|year=2015|volume=26|issue=13|pages=1911–1912|doi=10.1055/s-0034-1380924|title=Fluoroform (CHF3)|author=ShivaKumar Kyasa|doi-access=free}}</ref>

== Synthesis == About 20 million kg per year are produced industrially as both a by-product of and precursor to the manufacture of Teflon.<ref name=SynLett/> It is produced by reaction of chloroform with HF:<ref name=Ullmann>{{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}}</ref> :{{chem2|CHCl3 + 3 HF → CHF3 + 3 HCl}}

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

===Historical=== Fluoroform was first obtained by Maurice Meslans in the violent reaction of iodoform with dry silver fluoride in 1894.<ref>{{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}}</ref> The reaction was improved by Otto Ruff by substitution of silver fluoride by a mixture of mercury fluoride and calcium fluoride.<ref name="JACS_1937">{{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 | bibcode=1937JAChS..59.1200H }}</ref> 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.<ref name="JACS_1937"/>

== Industrial applications == {{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.

=== Organic chemistry === 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.<ref>{{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|bibcode=2011JAChS.13320901Z |issn=0002-7863}}</ref>

Fluoroform is a precursor of the Ruppert-Prakash reagent {{chem2|CF3Si(CH3)3}}, which is a source of the nucleophilic {{chem2|CF3−}} anion.<ref>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}}</ref><ref>{{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}}</ref>

== Greenhouse gas == [[File:HFC-23_mm.png|thumb|class=skin-invert-image|left|upright=1.2|HFC-23 measured by the Advanced Global Atmospheric Gases Experiment ([http://agage.mit.edu/ 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.]]

thumb|class=skin-invert-image|left|upright=1.2|Atmospheric concentration of HFC-23 vs. similar man-made gases (right graph), log scale. {{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.<ref name="R. Van Dorland-2007">{{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 }}</ref> The atmospheric lifetime is 270 years.<ref name="R. Van Dorland-2007"/>

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.<ref>{{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|article-number=2009GL041195 |pages=n/a|bibcode=2010GeoRL..37.2808M|s2cid=13583576 |url=https://escholarship.org/uc/item/3f31077f}}</ref>

However, research in 2024 strongly indicates that the HFC-23 emission decrease is much less than has been reported and does not meet the internationally agreed Kigali Amendment of 2020.<ref>{{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}}</ref><ref>{{Cite journal |last1=Adam |first1=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 |journal=Communications Earth & Environment |language=en |volume=5 |issue=1 |pages=1–8 |article-number=783 |doi=10.1038/s43247-024-01946-y |pmid=39717369 |issn=2662-4435|pmc=11663144 |bibcode=2024ComEE...5..783A }}</ref>

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.<ref>{{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 }}</ref><ref>[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</ref><ref>[https://www.nytimes.com/interactive/2012/08/09/world/subsidies-for-a-global-warming-gas.html ''Subsidies for a Global Warming Gas'']</ref> 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.<ref>{{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}}</ref>

== Additional physical properties == {| class="wikitable" |- ! Property ! Value |- | Density (ρ) at -100 °C (liquid) | 1.52 g/cm3 |- | Density (ρ) at -82.1 °C (liquid) | 1.431 g/cm3 |- | Density (ρ) at -82.1 °C (gas) | 4.57 kg/m3 |- | Density (ρ) at 0 °C (gas) | 2.86 kg/m3 |- | Density (ρ) at 15 °C (gas) | 2.99 kg/m3 |- | Dipole moment | 1.649 D |- | Critical pressure (pc) | 4.816 MPa (48.16 bar) |- | Critical temperature (Tc) | 25.7 °C (299 K) |- | Critical density (ρc) | 7.52 mol/l |- | Compressibility factor (Z) | 0.9913 |- | Acentric factor (ω) | 0.26414 |- | Viscosity (η) at 25 °C | 14.4 μPa.s (0.0144 cP) |- | Molar specific heat at constant volume (CV) | 51.577 J.mol−1.K−1 |- | Latent heat of vaporization (lb) | 257.91 kJ.kg−1 |}

== References == {{Reflist}}

== Literature == *{{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 | bibcode=2003JFluC.123...21M }}

== External links == * {{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] {{Webarchive|url=https://web.archive.org/web/20070930211732/http://rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=a801406j&JournalCode=CC |date=2007-09-30 }}

Category:Fluoroalkanes Category:Halomethanes Category:Refrigerants Category:Fire suppression agents Category:Greenhouse gases Category:Trifluoromethyl compounds Category:Hydrofluorocarbons