Trifluoromethanesulfonic anhydride

Trifluoromethanesulfonic anhydride, also known as triflic anhydride, is the chemical compound with the formula (CF₃SO₂)₂O. It is the acid anhydride derived from triflic acid. This compound is a strong electrophile, useful for introducing the triflyl group, CF₃SO₂. Abbreviated Tf₂O, triflic anhydride is the acid anhydride of the superacid triflic acid, CF₃SO₂OH.^[2][3]

Trifluoromethanesulfonic anhydride

Skeletal formula of triflic anhydride
Names
Preferred IUPAC name Trifluoromethanesulfonic anhydride
Identifiers
CAS Number	358-23-6 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:48509
ChemSpider	61068
ECHA InfoCard	100.006.016
EC Number	206-616-8
PubChem CID	67749
UNII	8W034LHG1U Y
CompTox Dashboard (EPA)	DTXSID501014629
InChI InChI=1S/C2F6O5S2/c3-1(4,5)14(9,10)13-15(11,12)2(6,7)8 Key: WJKHJLXJJJATHN-UHFFFAOYSA-N
SMILES C(F)(F)(F)S(=O)(=O)OS(=O)(=O)C(F)(F)F
Properties
Chemical formula	C2F6O5S2
Molar mass	282.13 g·mol−1
Appearance	colourless liquid
Density	1.6770 g/mL
Boiling point	82[1] °C (180 °F; 355 K)
Solubility in water	Reacts to form Triflic acid
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H272, H302, H314, H335
NFPA 704 (fire diamond)	4 0 3 W OX
Safety data sheet (SDS)	Fisher MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Preparation and uses

Triflic anhydride is prepared by dehydration of triflic acid using P₄O₁₀.^[2]

Triflic anhydride is useful for converting ketones into enol triflates.^[4]

In a representative application, is used to convert an imine into a NTf group.^[5] It will convert phenols into a triflic ester, which enables cleavage of the C-O bond.^[6][7]

Assay

The typical impurity in triflic anhydride is triflic acid, which is also a colorless liquid. Samples of triflic anhydride can be assayed by ¹⁹F NMR spectroscopy: −72.6 ppm^[8] vs. −77.3 for TfOH (std CFCl₃).

Safety

It is an aggressive electrophile and readily hydrolyzes to the strong acid triflic acid. It is very harmful to skin and eyes.^[9]

See also

• Methanesulfonic anhydride