Trifluoroacetic acid

Trifluoroacetic acid
General
Systematic name	trifluoroethanoic acid
Other names	perfluoroacetic acid trifluoracetic acid TFA
Molecular formula	C2HF3O2
SMILES	FC(F)(F)C(O)=O
Molar mass	114.03 g/mol
Appearance	colorless liquid
CAS number	[76-05-1]
Properties
Density and phase	1.5351 g/cm3, 20 °C
Solubility in water	miscible
Melting point	-15.4 °C; 257.75 K
Boiling point	72.4 °C; 345.55 K
Acidity (pKa)	0.3
Viscosity	? cP at ? °C
Hazards
MSDS	External MSDS
Main hazards	corrosive
NFPA 704
Flash point	? °C
R/S statement	R: Template:R20 Template:R35 Template:R52/53 S: Template:S9 Template:S26 Template:S27 Template:S28 Template:S45 Template:S61
RTECS number	?
Related compounds
Related compounds	acetic acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Trifluoroacetic acid (TFA) is a strong, hygroscopic, non-oxidizing, organic acid with a molecular formula C₂HF₃O₂. The molecular structure is similar to acetic acid, with substitution of three fluorine atoms on the methyl group. The electronic-withdrawing nature of the fluorine atoms stabilizes the dissociated anion, leading to stronger acidity compared to acetic acid. TFA is a reagent used frequently in organic synthesis due to its nature as an organic-soluble strong acid. It is also frequently used as a buffer in liquid chromatography for separation of organic compounds, particularly peptides and small proteins.

Synthesis

Electrofluorination of acetic acid with the Simons method is the best way to obtain trifluoroacetic acid. The anodic reaction of the electrolysis of a mixture of hydrogen fluoride and acetic acid below the voltage at which elemental fluorine (F₂) develops is a mild reaction which leaves the carboxylic group intact.