Fluoroform

  (Redirected from FE-13)

Trifluoromethane or fluoroform is the chemical compound with the formula CHF3. It is one of the "haloforms", a class of compounds with the formula 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.[2]

Fluoroform
Fluoroform.svg
Fluoroform-3D-vdW.png
Names
IUPAC name
Trifluoromethane
Other names
Fluoroform, carbon trifluoride, methyl trifluoride, Fluoryl, Freon 23, Arcton 1, HFC 23, R-23, FE-13, UN 1984
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.000.794 Edit this at Wikidata
EC Number
  • 200-872-4
RTECS number
  • PB6900000
UNII
  • InChI=1S/CHF3/c2-1(3)4/h1H checkY
    Key: XPDWGBQVDMORPB-UHFFFAOYSA-N checkY
  • InChI=1/CHF3/c2-1(3)4/h1H
    Key: XPDWGBQVDMORPB-UHFFFAOYAM
  • FC(F)F
Properties
CHF3
Molar mass 70.01 g/mol
Appearance Colorless gas
Density 2.946 kg·m−3 (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
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]
GHS04: Compressed Gas
Warning
H280
P403
NFPA 704 (fire diamond)
2
0
0
Flash point Non-flammable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

SynthesisEdit

About 20M kg/y are produced industrially as both a by-product of and precursor to the manufacture of Teflon.[2] It is produced by reaction of chloroform with HF:[3]

CHCl3 + 3 HF → CHF3 + 3 HCl

It is also generated biologically in small amounts apparently by decarboxylation of trifluoroacetic acid.[4]

HistoricalEdit

Fluoroform was first obtained by Maurice Meslans in the violent reaction of iodoform with dry silver fluoride in 1894.[5] The reaction was improved by Otto Ruff by substitution of silver fluoride by a mixture of mercury fluoride and calcium fluoride.[6] 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 bromodifluoro methane in the reaction of antimony trifluoride with bromoform and finishing the reaction with mercury fluoride the first efficient synthesis method was found by Henne.[6]

Industrial applicationsEdit

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. 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 chemistryEdit

Fluoroform is weakly acidic with a pKa = 25–28 and quite inert. Attempted deprotonation results in defluorination to generate F and difluorocarbene (CF2). Some organocopper and organocadmium compounds have been developed as trifluoromethylation reagents.[7]

Fluoroform is a precursor of the Ruppert-Prakash reagent CF3Si(CH3)3, which is a source of the nucleophilic CF3 anion.[8][9]

Greenhouse gasEdit

 
HFC-23 measured by the Advanced Global Atmospheric Gases Experiment (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.
 
Atmospheric concentration of HFC-23 vs. similar man-made gases (right graph), log scale.

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.[10] The atmospheric lifetime is 270 years.[10]

HFC-23 was the most abundant HFC in the global atmosphere until around 2001, which is 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.[11]

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.[12][13][14] 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.[15]

ReferencesEdit

  1. ^ GHS: GESTIS 038260
  2. ^ a b ShivaKumar Kyasa (2015). "Fluoroform (CHF3)". Synlett. 26 (13): 1911–1912. doi:10.1055/s-0034-1380924.
  3. ^ G. Siegemund; W. Schwertfeger; A. Feiring; B. Smart; F. Behr; H. Vogel; B. McKusick (2005). "Fluorine Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_349.
  4. ^ Kirschner, E., Chemical and Engineering News 1994, 8.
  5. ^ Meslans M. M. (1894). "Recherches sur quelques fluorures organiques de la série grasse". Annales de chimie et de physique. 7 (1): 346–423.
  6. ^ a b Henne A. L. (1937). "Fluoroform". Journal of the American Chemical Society. 59 (7): 1200–1202. doi:10.1021/ja01286a012.
  7. ^ Zanardi, Alessandro; Novikov, Maxim A.; Martin, Eddy; Benet-Buchholz, Jordi; Grushin, Vladimir V. (2011-12-28). "Direct Cupration of Fluoroform". Journal of the American Chemical Society. 133 (51): 20901–20913. doi:10.1021/ja2081026. ISSN 0002-7863. PMID 22136628.
  8. ^ 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
  9. ^ Prakash, G. K. Surya; Jog, Parag V.; Batamack, Patrice T. D.; Olah, George A. (2012-12-07). "Taming of Fluoroform: Direct Nucleophilic Trifluoromethylation of Si, B, S, and C Centers". Science. 338 (6112): 1324–1327. Bibcode:2012Sci...338.1324P. doi:10.1126/science.1227859. ISSN 0036-8075. PMID 23224551. S2CID 206544170.
  10. ^ a b Forster, P.; V. Ramaswamy; P. Artaxo; T. Berntsen; R. Betts; D.W. Fahey; J. Haywood; J. Lean; D.C. Lowe; G. Myhre; J. Nganga; R. Prinn; G. Raga; M. Schulz & R. Van Dorland (2007). "Changes in Atmospheric Constituents and in Radiative Forcing." (PDF). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change.
  11. ^ Montzka, S. A.; Kuijpers, L.; Battle, M. O.; Aydin, M.; Verhulst, K. R.; Saltzman, E. S.; Fahey, D. W. (2010). "Recent increases in global HFC-23 emissions". Geophysical Research Letters. 37 (2): n/a. Bibcode:2010GeoRL..37.2808M. doi:10.1029/2009GL041195. S2CID 13583576.
  12. ^ "Archived copy". Archived from the original on 2011-07-21. Retrieved 2010-04-03.{{cite web}}: CS1 maint: archived copy as title (link)
  13. ^ Profits on Carbon Credits Drive Output of a Harmful Gas August 8, 2012 New York Times
  14. ^ Subsidies for a Global Warming Gas
  15. ^ 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.

LiteratureEdit

External linksEdit

Additional physical propertiesEdit

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 densityc) 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