Trifluoroacetic acid: Difference between revisions
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Corrected Density value |
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| MolarMass = 114.02 g/mol |
| MolarMass = 114.02 g/mol |
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| Appearance = colorless liquid |
| Appearance = colorless liquid |
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| Density = 1. |
| Density = 1.489 g/cm<sup>3</sup>, 20 °C |
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| Solubility = miscible |
| Solubility = miscible |
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| MeltingPtC = -15.4 |
| MeltingPtC = -15.4 |
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Revision as of 07:38, 19 May 2010
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| Names | |||
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| IUPAC name
2,2,2-Trifluoroacetic acid
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| Other names
Perfluoroacetic acid
Trifluoroethanoic acid TFA | |||
| Identifiers | |||
3D model (JSmol)
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| ChemSpider | |||
| ECHA InfoCard | 100.000.846 | ||
| RTECS number |
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CompTox Dashboard (EPA)
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| Properties | |||
| C2HF3O2 | |||
| Molar mass | 114.02 g/mol | ||
| Appearance | colorless liquid | ||
| Density | 1.489 g/cm3, 20 °C | ||
| Melting point | −15.4 °C (4.3 °F; 257.8 K) | ||
| Boiling point | 72.4 °C (162.3 °F; 345.5 K) | ||
| miscible | |||
| Acidity (pKa) | 0.3 | ||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards
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Highly corrosive | ||
| NFPA 704 (fire diamond) | |||
| Flash point | -3 °C | ||
| Related compounds | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Trifluoroacetic acid (TFA) is the simplest stable[1] perfluorinated carboxylic acid chemical compound, with the formula CF3CO2H. It is a strong carboxylic acid due to the influence of the electronegative trifluoromethyl group. TFA is almost 100,000-fold more acidic than acetic acid. TFA is widely used in organic chemistry.
Synthesis
Trifluoroacetic acid is prepared industrially by the electrofluorination of acetyl chloride and acetic anhydride, followed by hydrolysis of the resulting trifluoroacetyl fluoride:[2]
- CH3COCl + 4 HF → CF3COF + 3 H2 + HCl
- CF3COF + H2O → CF3CO2H + HF
An older route to TFA proceeds via the oxidation of 1,1,1-trifluoro-2,3,3-trichloropropene with potassium permanganate. The trifluorotrichloropropene can be prepared by Swarts fluorination of hexachloropropene.[3]
Uses
TFA is the precursor to trifluoroacetic anhydride and 2,2,2-trifluoroethanol. It is a reagent used in organic synthesis because of a combination of convenient properties: volatility, solubility in organic solvents, and its strength as an acid.[4]
Another use of TFA is in peptide synthesis, and related reactions where TFA is used as a strong acid to remove the t-butoxycarbonyl protecting group from boc-protected amines.
TFA is used to produce trifluoroacetate salts that serve as precursors to ceramic materials such as YBa2Cu3O{7-x}.[5]
As a solvent
It is also less oxidizing than sulfuric acid but more readily available in anhydrous form than many other acids. One complication to its use is that TFA forms an azeotrope with water (b. p. 105 °C). It is used in ion pairing agent in liquid chromatography (HPLC) of organic compounds, particularly peptides and small proteins.[6] TFA is a versatile solvent for NMR spectroscopy (for materials stable in acid). It is also used as a calibrant in mass spectrometry.[7]
References
- ^ The even simpler fluoroformic acid would be a very unstable compound; on formation it disintegrates immediately into hydrogen fluoride and carbon dioxide
- ^ G. Siegemund, W. Schwertfeger, A. Feiring, B. Smart, F. Behr, H. Vogel, B. McKusick “Fluorine Compounds, Organic” in “Ullmann’s Encyclopedia of Industrial Chemistry” 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a11 349
- ^ Max Gergel "Excuse me, would you like to buy a kilo of isopropyl bromide" 1979, Pierce Chemical Company. A vivid account is found in chapter 10.
- ^ Eidman, K. F.; Nichols, P. J. "Trifluoroacetic Acid" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. doi:10.1002/047084289
- ^ O. Castano, A. Cavallaro, A. Palau, J. C. Gonzalez, M. Rossell, T. Puig, F. Sandiumenge, N. Mestres, S. Pinol, A. Pomar, and X. Obradors (2003). "High quality YBa2Cu3O{7-x} thin films grown by trifluoroacetates metal-organic deposition". Supercond. Sci. Technol. 16: 45–53. doi:10.1088/0953-2048/16/1/309.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ "TFA (Proteomics Grade)". ProteoChem. Retrieved 2010-03-31.
{{cite web}}: Check|url=value (help) - ^ Stout, Steven J.; Dacunha, Adrian R. (1989). "Tuning and calibration in thermospray liquid chromatography/mass spectrometry using trifluoroacetic acid cluster ions". Analytical Chemistry. 61: 2126. doi:10.1021/ac00193a027.