Trifluoromethanesulfonic anhydride, also known as triflic anhydride, is the

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the formula (CF₃SO₂)₂O. It is the acid anhydride derived from

triflic acid Triflic acid, the short name for trifluoromethanesulfonic acid, TFMS, TFSA, HOTf or TfOH, is a sulfonic acid with the chemical formula CF3SO3H. It is one of the strongest known acids. Triflic acid is mainly used in research as a catalyst for este ...

. This compound is a strong

electrophile In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that carrie ...

, useful for introducing the triflyl group, CF₃SO₂. Abbreviated Tf₂O, triflic anhydride is the

acid anhydride An acid anhydride is a type of chemical compound derived by the removal of water molecules from an acid. In organic chemistry, organic acid anhydrides contain the functional group R(CO)O(CO)R'. Organic acid anhydrides often form when one equivale ...

of the strong acid

, CF₃SO₂OH.

Preparation and uses

Triflic anhydride is prepared by dehydration of triflic acid using P₄O₁₀. Triflic anhydride is useful for converting ketones into enol triflates. In a representative application, is used to convert an imine into a NTf group. It will convert

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...

s into a triflic ester, which enables cleavage of the C-O bond.

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 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.

References

{{Reflist Triflyl compounds Acid anhydrides Reagents for organic chemistry

Preparation and uses

Assay

Safety

See also

References