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 (CF
3SO
2)
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, CF
3SO
2. Abbreviated Tf
2O, 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
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 ...
, CF
3SO
2OH.
Preparation and uses
Triflic anhydride is prepared by dehydration of triflic acid using P
4O
10.
[
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.
See also
* Methanesulfonic anhydride
Methanesulfonic anhydride (Ms2O) is the acid anhydride of methanesulfonic acid. Like methanesulfonyl chloride (MsCl), it may be used to generate mesylates (methanesulfonyl esters).
Preparation & purification
Ms2O may be prepared by the dehydra ...
References
{{Reflist
Triflyl compounds
Acid anhydrides
Reagents for organic chemistry