Calcium fluoride potassium fluondes

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 fluonde or potassium fluoride 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 fluoride in 94% yield. Using tetrabuty lammonium fluoride in place of Aliquat... 

A slurry of pure calcium fluoride in a solution of potassium fluoride in methanol is slowly evaporated to dryness (KF CaF molar ratio of 1 5) for ca 1 h at 80 °C under reduced pressure Fluonnation of benzyl bromide for 2 h at 120 °C in sulfolane gives 74% yield (92% conversion), compared with 36% with potassium fluonde alone... 

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%... 

---