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| Names | |||
|---|---|---|---|
| IUPAC name Trifluoromethane | |||
| Other names Fluoroform, carbon trifluoride,[citation needed] methyl trifluoride, Fluoryl, Freon 23, Arcton 1 | |||
| Identifiers | |||
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3D model (JSmol) | |||
| Abbreviations | HFC 23, R-23,FE-13, UN 1984 | ||
| ChEBI | |||
| ChemSpider |
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| ECHA InfoCard | 100.000.794 | ||
| EC Number |
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| RTECS number |
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| UNII | |||
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| Properties | |||
| CHF3 | |||
| Molar mass | 70.014 g·mol−1 | ||
| Appearance | Colorless gas | ||
| Density | 2.946 kg/m3 (gas, 1 bar, 15 °C) | ||
| Melting point | −155.2 °C (−247.4 °F; 118.0 K) | ||
| Boiling point | −82.1 °C (−115.8 °F; 191.1 K) | ||
| 1 g/L | |||
| Solubility in organic solvents | Soluble | ||
| Vapor pressure | 4.38 MPa at 20 °C | ||
Henry's law constant (kH) | 0.013 mol·kg−1·bar−1 | ||
| Acidity (pKa) | 25–28 | ||
| Structure | |||
| Tetrahedral | |||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards | Nervous system depression | ||
| GHS labelling:[1] | |||
 | |||
| Warning | |||
| H280 | |||
| P403 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | Non-flammable | ||
| Related compounds | |||
Related compounds |
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Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Fluoroform, ortrifluoromethane, is thechemical compound with the formulaCHF3. It is ahydrofluorocarbon as well as being a part of thehaloforms, a class of compounds with the formulaCHX3 (X =halogen) with C3vsymmetry. Fluoroform is used in diverse applications inorganic synthesis. It is not anozone depleter but is agreenhouse gas.[2]
About 20 million kg per year are produced industrially as both a by-product of and precursor to the manufacture ofTeflon.[2] It is produced by reaction ofchloroform withHF:[3]
It is also generated biologically in small amounts apparently bydecarboxylation oftrifluoroacetic acid.[4]
Fluoroform was first obtained byMaurice Meslans in the violent reaction ofiodoform with drysilver fluoride in 1894.[5] The reaction was improved byOtto Ruff by substitution of silver fluoride by a mixture ofmercury fluoride andcalcium fluoride.[6] The exchange reaction works with iodoform andbromoform, and the exchange of the first twohalogen atoms by fluorine is vigorous. By changing to a two step process, first forming abromodifluoromethane in the reaction ofantimony trifluoride with bromoform and finishing the reaction with mercury fluoride the first efficient synthesis method was found by Henne.[6]
CHF3 is used in thesemiconductorindustry inplasma etching ofsilicon oxide andsilicon nitride. Known as R-23 or HFC-23, it was also a usefulrefrigerant, sometimes as a replacement forchlorotrifluoromethane (CFC-13) and is a byproduct of its manufacture.
When used as a fire suppressant, the fluoroform carries theDuPont trade name, FE-13.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 forHalon 1301(CFC-13B1) infire suppression systems as a total floodinggaseous fire suppression agent.
Fluoroform is weakly acidic with a pKa = 25–28 and quite inert. Attempted deprotonation results in defluorination to generateF− anddifluorocarbene (CF2). Some organocopper andorganocadmium compounds have been developed as trifluoromethylation reagents.[7]
Fluoroform is a precursor of the Ruppert-Prakash reagentCF3Si(CH3)3, which is a source of the nucleophilicCF−3 anion.[8][9]
CHF3 is a potentgreenhouse 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-yrglobal warming potential, is slightly larger at 14,800 for HFC-23.[10]The atmospheric lifetime is 270 years.[10]
HFC-23 was the most abundant HFC in the global atmosphere until around 2001, when the global mean concentration ofHFC-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 refrigerantHCFC-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.[11]
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 agreedKigali Amendment of 2020.[12][13]
TheUNFCCC Clean Development Mechanismprovided 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.[14][15][16] Emissions of all HFCs are included in the UNFCCCs Kyoto Protocol. To mitigate its impact,CHF3 can be destroyed with electric plasma arc technologies or by high temperature incineration.[17]
| 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 |
