Triflic anhydride



Triflic anhydride is the chemical compound with the formula (CF3SO2)2O. This compound is a particularly strong electrophile, useful for introducing the CF3SO2 group. Triflic anhydride is the acid anhydride of the strong acid triflic acid, CF3SO2OH.

It can be assayed by 19F NMR spectroscopy: −72.6 ppm vs. -77.3 for TfOH (std CFCl3).

Preparation
The compound is prepared by dehydration of triflic acid using phosphorus pentoxide:
 * 2CF3SO2OH + P4O10 &rarr;   [CF3SO2]2O  +  P4O8(OH)2

Illustrative uses
In a representative application, is used to convert an imine into a NTf group.

It will convert phenols into a triflic ester, which enables cleavage of the C-O bond.