|Jmol-3D images||Image 1|
|Molar mass||114.02 g/mol|
|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)|
|Solubility in water||miscible|
|Acidity (pKa)||0.23 |
|R-phrases||R20 R35 R52/53|
|S-phrases||S9 S26 S27 S28 S45 S61|
|Main hazards||Highly corrosive|
|Flash point||−3 °C (27 °F; 270 K)|
|Related perfluorinated acids||Perfluorooctanoic acid
|Related compounds||Acetic acid
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)|
|(what is: / ?)|
Trifluoroacetic acid (TFA) is an organofluorine compound with the chemical formula CF3CO2H. It is a colorless liquid with a sharp odor similar to vinegar, but stronger in acidity. TFA is an analogue of acetic acid with the three hydrogen atoms replaced by three fluorine atoms. The acidity of TFA is approximately 34,000 times stronger than that of acetic acid due to the electronegativity of the trifluoromethyl group. TFA is widely used in organic chemistry for various purposes.
3COCl + 4 HF → CF
3COF + 3 H
2 + HCl
3COF + H
2O → CF
3COOH + 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.
TFA is the precursor to many other fluorinated compounds such as 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. TFA 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).
At a low concentration, TFA is used as an ion pairing agent in liquid chromatography (HPLC) of organic compounds, particularly peptides and small proteins. TFA is a versatile solvent for NMR spectroscopy (for materials stable in acid). It is also used as a calibrant in mass spectrometry.
TFA is used to produce trifluoroacetate salts.
Trifluoroacetic acid is a corrosive acid but it does not pose the hazards associated with hydrofluoric acid because the carbon-fluorine bond is not labile. Toxic. Irreversible inhibitor of acetylcholinesterase enzyme.
- Ref 1 in Milne, J. B.; Parker, T. J. (1981). "Dissociation constant of aqueous trifluoroacetic acid by cryoscopy and conductivity". Journal of Solution Chemistry 10 (7): 479. doi:10.1007/BF00652082.
- Note: Calculated from Ka ratio of TFA and acetic acid
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- Stout, Steven J.; Dacunha, Adrian R. (1989). "Tuning and calibration in thermospray liquid chromatography/mass spectrometry using trifluoroacetic acid cluster ions". Analytical Chemistry 61 (18): 2126. doi:10.1021/ac00193a027.
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