'Tetra-''n''-butylammonium fluoride' or 'TBAF' is a
quaternary ammonium salt with the chemical formula (CH
3CH
2CH
2CH
2)
4N
+F
-. It is commercially available as the trihydrate and as a solution in
tetrahydrofuran.
In the laboratory the compound is usually encountered in the latter form as a source of organic-soluble
fluoride ion to remove
silyl ether protecting groups. It is also used as a
phase transfer catalyst and as a mild
base.
As fluoride is such a strong
hydrogen bond acceptor it is quite impossible to dry hydrated samples. Heating to 77 °C under vacuum causes decomposition to the
hydrogen difluoride salt,
[{{cite journal | author= Ramesh K. Sharma, James L. Fry | title= Instability of anhydrous tetra-n-alkylammonium fluorides | journal= Journal of Organic Chemistry | year= 1983 | volume= 48 | pages= 2112-4 |id=] and samples dried at 40 °C under high vacuum still contain 10-30 mol % of water and some 10 % of difluoride.
[{{cite journal | author= D. Phillip Cox, Jacek Terpinski, Witold Lawrynowicz | title= 'Anhydrous' tetrabutylammonium fluoride: a mild but highly efficient source of nucleophilic fluoride ion | journal= Journal of Organic Chemistry | year= 1984 | volume= 49 | pages= 3216-9 |id=] Preparing anhydrous samples is of interest as the basicity of
fluoride increases by more than 20
p''K'' units on passing from aqueous to aprotic solvent. Recently, a preparation of anhydrous tetra-''n''-butylammonium fluoride from hexafluorobenzene and tetrabutylammonium cyanide has been reported. Despite the considerable basicity of "naked" fluoride ion, in the absence of water, solutions of the salt in
acetonitrile and
dimethylsulfoxide are surprisingly stable towards
elimination.
[{{cite journal | author= Haoran Sun and Stephen G. DiMagno | title= Anhydrous Tetrabutylammonium Fluoride | journal= Journal of the American Chemical Society | year= 2005 | volume= 127 | pages= 2050-1| id=]
References
العربية
中国
Français
Deutsch
Ελληνική
हिन्दी
Italiano
日本語
Português
Русский
Español
