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TASF reagent

TASF reagent
IUPAC name Tris(dimethylamino)sulfonium difluorotrimethylsilicate
CAS number 59218-87-0
SMILES C\[N](C)=S(N(C)C)/N(C)C.C[Si](C)(C)(F)F
Molecular formula C9H272N3SSi
Molar mass 275.48 g mol-1
Appearance Colorless solid
Melting point

98-101 °C

Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

The TASF reagent or tris(dimethylamino)sulfonium difluorotrimethylsilicate is a reagent in organic chemistry with structural formula [((CH3)2N)3S]+[F2Si(CH3)3]-. It is an anhydrous source of fluoride and is used to cleave silyl ether protective groups. Many other fluoride reagents are known, but few are truly anhydrous, because of the extraordinary basicity of "naked" F-. In TASF, the fluoride is masked as an adduct with the weak Lewis acid trimethylsilylfluoride (FSi(CH3)3). The sulfonium cation ((CH3)2N)3S+ is unusually non-electrophilic due to the electron-donating properties of the three (CH3)2N substituents.

This compound is prepared from sulfur tetrafluoride:

3 (CH3)2NSi(CH3)3 + SF4 → 2 (CH3)3SiF + [((CH3)2N)3S]+[F2Si(CH3)3]-

The colorless salt precipitates from the reaction solvent, diethyl ether.


  • W. J. Middleton, TRIS(DIMETHYLAMINO)SULFONIUM DIFLUOROTRIMETHYLSILICATE, Organic Syntheses, Coll. Vol. 7, p.528 (1990); Vol. 64, p.221 (1986) Online article
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "TASF_reagent". A list of authors is available in Wikipedia.
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