Tetrabutylammonium Fluoride (Fluoride Soaps)

The fluoride ion is important to synthetic chemistry, often because it can be used to cleave silyl ethers (the silicon analogue of a carbon ether). Fluoride is notorious for holding onto water (like any tiny ion - lithium is about as bad), so even an "anhydrous" solution of TBAF in (say) THF will often contain ca 5% water. The less water you have, the more "naked" fluoride anion you have, which is much, much more reactive than aquated fluoride.