Fluoroform: Difference between revisions
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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|pages=n/a|bibcode=2010GeoRL..37.2808M|s2cid=13583576 |url=https://escholarship.org/uc/item/3f31077f}}</ref> | 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|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 | 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 |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 }}</ref> | ||
The [[United Nations Framework Convention on Climate Change|UNFCCC]] Clean Development Mechanism [[Clean Development Mechanism#Destruction of HFC-23|provided funding and facilitated the destruction of HFC-23]]. | The [[United Nations Framework Convention on Climate Change|UNFCCC]] Clean Development Mechanism [[Clean Development Mechanism#Destruction of HFC-23|provided funding and facilitated the destruction of HFC-23]]. | ||
Latest revision as of 05:37, 23 June 2025
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Fluoroform, or trifluoromethane, is the chemical compound with the formula Template:Chem2. It is a hydrofluorocarbon as well as being a part of the haloforms, a class of compounds with the formula Template:Chem2 (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.[1]
Synthesis
About 20 million kg per year are produced industrially as both a by-product of and precursor to the manufacture of Teflon.[1] It is produced by reaction of chloroform with HF:[2]
It is also generated biologically in small amounts apparently by decarboxylation of trifluoroacetic acid.[3]
Historical
Fluoroform was first obtained by Maurice Meslans in the violent reaction of iodoform with dry silver fluoride in 1894.[4] The reaction was improved by Otto Ruff by substitution of silver fluoride by a mixture of mercury fluoride and calcium fluoride.[5] 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.[5]
Industrial applications
Template:Chem2 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. Template:Chem2 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 pKa = 25–28 and quite inert. Attempted deprotonation results in defluorination to generate Template:Chem2 and difluorocarbene (Template:Chem2). Some organocopper and organocadmium compounds have been developed as trifluoromethylation reagents.[6]
Fluoroform is a precursor of the Ruppert-Prakash reagent [[Trifluoromethyltrimethylsilane|Template:Chem2]], which is a source of the nucleophilic Template:Chem2 anion.[7][8]
Greenhouse gas
Template:Chem2 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.[9] The atmospheric lifetime is 270 years.[9]
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.[10]
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.[11][12]
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.[13][14][15] Emissions of all HFCs are included in the UNFCCCs Kyoto Protocol. To mitigate its impact, Template:Chem2 can be destroyed with electric plasma arc technologies or by high temperature incineration.[16]
Additional physical properties
| 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
Literature
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External links
- International Chemical Safety Card 0577
- MSDS at Oxford University
- MSDS at mathesontrigas.com
- Coupling of fluoroform with aldehydes using an electrogenerated base
Template:Halomethanes Template:Fluorine compounds
- ↑ a b Script error: No such module "Citation/CS1".
- ↑ Template:Ullmann
- ↑ Kirschner, E., Chemical and Engineering News 1994, 8.
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- ↑ a b Script error: No such module "Citation/CS1".
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- ↑ Rozen, S.; Hagooly, A. "Fluoroform" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. Script error: No such module "doi".
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- ↑ Profits on Carbon Credits Drive Output of a Harmful Gas August 8, 2012 New York Times
- ↑ Subsidies for a Global Warming Gas
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