Fluoroform
From Wikipedia, the free encyclopedia
| Fluoroform | |
|---|---|
 |
 |
| IUPAC name | Trifluoromethane |
| Other names | Fluoroform, Carbon trifluoride, Methyl trifluoride, Fluoryl, Freon 23, Arcton 1, HFC 23, R-23, FE-13, UN 1984 |
| Identifiers | |
| CAS number | [75-46-7] |
| PubChem | |
| EINECS number | |
| ChEBI | |
| RTECS number | PB6900000 |
| SMILES | C(F)(F)F |
| InChI | 1/CHF3/c2-1(3)4/h1H |
| Properties | |
| Molecular formula | CHF3 |
| Molar mass | 70.01 g/mol |
| Appearance | Colorless gas |
| Melting point |
-155.2 °C (117.95 K) |
| Boiling point |
-82.1°C (191.05 K) |
| Solubility in water | 1 g/l |
| Solubility in organic solvents | Soluble |
| Vapor pressure | 4.38 MPa at 20 °C |
| kH | 0.013 mol.kg-1.bar-1 |
| Acidity (pKa) | 25 - 28 |
| Hazards | |
| Main hazards | Nervous system depression |
| NFPA 704 |
 0
1
0
|
| S-phrases | S38 |
| Flash point | Non-flammable |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
|
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). Fluoroform is used in diverse niche applications and is produced as a by-product of the manufacture of Teflon. Fluoroform is also generated biologically in small amounts apparently by decarboxylation of trifluoroacetic acid.[1]
Contents |
[edit] 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 |
[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[cfc-13b1] in fire suppression systems as a total flooding gaseous fire suppression agent. It is also used as a low temperature refrigerant (replacement for Chlorotrifluoromethane (cfc-13). It is a byproduct of its manufacture. 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] According to researchers, it is the most abundant of hydrofluorocarbons (HFCs). Its usage has been regulated since December 1997 at Kyoto climate conference.
[edit] Chemistry
It was first obtained by Meslans in the violent reaction of iodoform with dry silver fluoride in 1894. [3] The reaction was improved by Otto 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 method 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 CF3Si(CH3)3[6]
[edit] See also
- Haloalkane
- Halomethane
- Trihalomethane
- Fluoromethane
- Difluoromethane
- Tetrafluoromethane
- Chloroform
- Bromoform
- Iodoform
[edit] References
- ^ Kirschner, E., Chemical and Engineering News 1994, 8.
- ^ "Refrigerant Data Summary" (2001). 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:.
- ^ Henne A. L. (1937). "Fluoroform". Journal of the American Chemical Society 59 (7): 1200–1202. doi:.
- ^ 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:.
- 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:.
