Tetrabutylammonium fluonde

Early workers using anhydrous tetrabutylammonium fluonde (TBAF) may have actually used mixtures of TBAF and tetrabutylammonium bifluonde It is known that excessive drying at 77 °C in a vacuum below 2 torr (1 torr =133 322 Pa) produces the bifluonde salt [20] TBAF can be obtained by drying commer... 

Tetrabutylammonium fluonde tnhydrate obtained from Fluka AG was dned over phosphorus pentoxide for 48 hr at a pressure of 0 1 mm The hygroscopic fluonde was pulvenzed with the aid of a spatula in a dry atmosphere The checkers prepared the dry salt by this method using matenal obtained from Tndom Chemical, Inc... 

The use of cesium fluoride is limited because of its cost and its availability as a truly anhydrous reagent. Its use with 18-crown-6 shows a 5 times higher rate for the formation of benzyl fluoride from benzyl bromide when compared with cesium fluoride or potassium fluonde supported on calcium fluoride [21] Either cesium fluoride or potassium fluoride supported on calcium fluoride (Procedures 5a and 5b, p 194) provides about a twofold improvement over either unsupported alkali metal fluoride [55, 69]. Cesium fluoride and Aliquat 336 convert benzyl bromide to the fluonde in 94% yield. Using tetrabutylammonium fluoride in place of Aliquat... 

Various sources of fluoride ion have been investigated, of which highly nucleophilic tetraalkylammomum fluondes are the most effective Thus, fluoro alkyl halides and N (fluoroalkyl)amines are efficiently synthesized by treatment of the corresponding trifluoromethanesulfonic esters with tetrabutylammonium fluoride trihydrate in aprotic solvents [50] (equation 34) The displacement reactions proceed quantitatively at room temperature within seconds, but tail with hydrogen fluoride-pyridine and give reasonable yields only with hydrogen fluo ride-alkylamine reagents... 

Epoxides are regio- and stereoselectively transformed into fluorohydnns by silicon tetrafluoride in the presence of a Lewis base, such as diisopropyleth-ylamine and, in certain instances, water or tetrabutylammonium fluoride The reactions proceed under very mild conditions (0 to 20 °C in 1,2-dichloroethane or diethyl ether) and are highly chemoselective alkenes, ethers, long-chain internal oxiranes, and carbon-silicon bonds remain intact The stereochemical outcome of the epoxide ring opening with silicon tetrafluoride depends on an additive used, without addition of water or a quaternary ammonium fluonde, cis fluorohydnns are formed, whereas in the presence of these additives, only anti opening leading to trans isomers is observed [17,18] (Table 2)... 

Dehydrochlorination of bis(tnfluoromethyUhio)acetyl chloride with calcium oxide gives bis(tnfluoromethylthio)ketene [5] (equation 6) Elimination of hydrogen chlonde or hydrogen bromide by means of tetrabutylammonium or potassium fluoride from vinylic chlorides or bromides leads to acetylenes or allenes [d] (equation 7) Addition of dicyclohexyl-18-crown-6 ether raises the yields of potassium fluonde-promoted elimination of hydrogen bromide from (Z)-P-bromo-p-ni-trostyrene m acctonitnle from 0 to 53-71 % In dimethyl formamide, yields increase from 28-35% to 58-68%... 

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