Fluoroform

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). CHF₃ is used in diverse niche applications. It is produced as a by-product of the manufacture of Teflon. CHF₃ is generated biologically in small amounts apparently by decarboxylation of trifluoroacetic acid.^[1]

1 Industrial applications
2 Chemistry
3 Organic chemistry
4 References
5 External links

[edit] Industrial applications

CHF₃ is used in the semiconductor industry in plasma etching of silicon oxide and silicon nitride.

As a refrigerant, CHF₃ is known as R-23 or HFC-23.

HFC-23 is also used as a replacement for Halon 1301 in fire suppression systems as a total flooding gaseous fire suppression agent. When used as a fire suppressant, the chemical 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.

CHF₃ is a potent greenhouse gas. The secretariat of the Clean Development Mechanism estimates that a ton of HFC-23 in the atmosphere has the same effect as 11,700 tons of carbon dioxide. The atmospheric lifetime is 260 years.^[2]

[edit] Chemistry

It was first obtained by Meslans in the violent reaction of iodoform with dry silver fluoride in 1894. ^[3] The reaction was impoved by Ruff by substitution of silver fluoride by a mixture of mercury fluoride and calcium fluoride.^[4] 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 methode was found by Henne.^[5]

[edit] Organic chemistry

CHF₃ is a reagent to generate CF₃^- reagents by deprotonation. The molecule is weakly acidic with a pKa = 25–28. It is a precursor to CHF₃Si(CH₃)₃^[6]

[edit] References

^ Kirschner, E., Chemical and Engineering News 1994, 8.
^ (2001) "Refrigerant Data Summary". Engineered Systems 18: 74-88.
^ Meslans M. M. (1894). ".". Annales de chimie et de physique 7 (1): 346-423.
^ Henne A. L. (1937). "Fluoroform". Journal of the American Chemical Society 59 (7): 1200-1202. DOI:10.1021/ja01286a012.
^ Henne A. L. (1937). "Fluoroform". Journal of the American Chemical Society 59 (7): 1200-1202. DOI:10.1021/ja01286a012.
^ Rozen, S.; Hagooly, A. "Fluoroform" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI:10.1002/047084289 10.1002/047084289

McBee E. T. (1947). "Fluorine Chemistry". Industrial & Engineering Chemistry 39 (3): 236 - 237. DOI:10.1021/ie50447a002.
Oram D. E., Sturges W. T., Penkett S. A., McCulloch A., Fraser P. J. (1998). "Growth of fluoroform (CHF₃, HFC-23) in the background atmosphere". Geophysical Research Letters 25 (1): 236 - 237.
McCulloch A. (2003). "Fluorocarbons in the global environment: a review of the important interactions with atmospheric chemistry and physics". Journal of Fluorine Chemistry 123 (1): 21-29. DOI:10.1016/S0022-1139(03)00105-2.