Trifluoroacetic anhydride (TFAA) is the acid anhydride of trifluoroacetic acid

Trifluoroacetic acid

Trifluoroacetic acid is the simplest stable 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...

. In particular, trifluoroacetic anhydride is the perfluorinated derivative of acetic anhydride

Acetic anhydride

Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula 2O. Commonly abbreviated Ac2O, it is the simplest isolatable acid anhydride and is a widely used reagent in organic synthesis...

. Like many acid anhydrides, it may be used to introduce the corresponding trifluoroacetyl group. The corresponding trifluoroacetyl chloride, is a gas, making it inconvenient to work with. Trifluoroacetic anhydride is the recommended desiccant

Desiccant

A desiccant is a hygroscopic substance that induces or sustains a state of dryness in its local vicinity in a moderately well-sealed container....

 for trifluoroacetic acid.

Preparation

Trifluoroacetic anhydride may be prepared from trifluoroacetic acid by dehydrating with excess α-halogenated acid chlorides. For example, with dichloroacetyl chloride:

2 CF₃COOH + Cl₂CHCOCl → (CF₃CO)₂O + Cl₂CHCOOH + HCl