Trifluoroacetic acid

Trifluoroacetic acid

Names
IUPAC name Trifluoroacetic acid
Preferred IUPAC name Trifluoroacetic acid
Other names 2,2,2-Trifluoroacetic acid 2,2,2-Trifluoroethanoic acid Perfluoroacetic acid Trifluoroethanoic acid TFA
Identifiers
Jmol-3D images	Image
SMILES C(=O)(C(F)(F)F)O
Properties
Chemical formula	C2HF3O2 CF3COOH
Molar mass	114.02 g/mol
Appearance	Colorless fuming liquid
Odor	Strong pungent odor
Density	1.531 g/cm3 (20 °C) 1.489 g/cm3 (25 °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
Solubility	Reacts with alkali, amines Miscible with acetone, benzene, carbon tetrachloride, diethyl ether, ethanol, hexane
Vapor pressure	82.5 mmHg (20 °C)
Acidity (pKa)	0.23
Hazards
Safety data sheet	Sigma-Aldrich
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (Median dose)	200 mg/kg (rat, oral)
Related compounds
Related compounds	Acetic acid Fluoroacetic acid Difluoroacetic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Trifluoroacetic acid (TFA) is an organofluorine compound, an organic acid with the formula CF₃COOH. 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.

Properties

Chemical

Trifluoroacetic acid reacts with bases to form trifluoroacetate salts.

CF₃COOH + MOH → CF₃COOM + H₂O

Decarboxylation of trifluoroacetic acid yields fluoroform.

Physical

Trifluoroacetic acid is a colorless volatile liquid, which fumes in open air, with a strong pungent acetic smell. It reacts with bases and amines, and it is miscible with water and a variety of organic solvents, like alcohols and ethers.

Availability

TFA is sold by various chemical suppliers, but it's not cheap.

Preparation

TFA can be synthesized by the electrofluorination of acetyl chloride and acetic anhydride, followed by hydrolysis of the resulting trifluoroacetyl fluoride:

CH₃COCl + 4 HF → CF₃COF + 3 H₂ + HCl

CF₃COF + H₂O → CF₃COOH + HF

An older route to TFA involves the oxidation of 1,1,1-trifluoro-2,3,3-trichloropropene with potassium permanganate, the latter being prepared by Swarts fluorination of hexachloropropene.

Oxidation of 1,1,1-trifluoroethane aka R-143a, a freon commonly used as refrigerent and propellant in canned air products will also yield TFA. The oxidation is done by mixing R-143a with air and passing the mixture through an electric discharge of 15,000 V. Water vapor is used as carrying medium, which also helps preventing the degradation of TFA and unreacted R-143a.

Projects

• Removal of nitrogen and oxygen protecting groups in organic chemistry
• Make copper (II) trifluoroacetate
• Make trifluoroacetic anhydride
• Make 2,2,2-trifluoroethanol
• Make holmium trifluoroacetate
• Compound collecting

Handling

Safety

TFA is volatile and corrosive and should be handled with proper protection, in well ventilated areas.

Storage

Trifluoroacetic acid should be kept in closed bottles, away from heat and light, in a corrosive acid cabinet. Don't store it near ammonia or other volatile chemicals.

Disposal

Trifluoroacetic acid can be neutralized with a base. Trifluoroacetates have low toxicity and generally do not require special disposal.

References

Relevant Sciencemadness threads

• Trifluoroacetic acid What to do with it?
• Trifluoroacetic acid from Freon 143a
• TFA Formation - How?
• Removing/neutralizing TFA from carbamate