TASF reagent

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ImageFile = TASF.png ImageSize = 200px
IUPACName = Tris(dimethylamino)sulfonium difluorotrimethylsilicate
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Section1 = Chembox Identifiers
CASNo = 59218-87-0
PubChem =
SMILES = C [N] (C)=S(N(C)C)/N(C)C.C [Si] (C)(C)(F)F
Section2 = Chembox Properties
C=9|H=27|F=2|Si=1|S=1|N=3
MolarMass = 275.48
Appearance = Colorless solid
Density =
MeltingPt = 98-101 °C
BoilingPt =
Solubility =
Section3 = Chembox Hazards
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FlashPt =
Autoignition = 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.

References

* W. J. Middleton, Tris(dimethylamino)sulfonium difluorotrimethylsilicate, Organic Syntheses, Coll. Vol. 7, p.528 (1990); Vol. 64, p.221 (1986) [http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?rxntypeid=122&prep=CV7P0528 Online article]