Potassium fluoride
It is an alkali halide salt and occurs naturally as the rare mineral carobbiite.Solutions of KF will etch glass due to the formation of soluble fluorosilicates, although HF is more effective.[4] In organic chemistry, KF can be used for the conversion of chlorocarbons into fluorocarbons, via the Finkelstein (alkyl halides)[5] and Halex reactions (aryl chlorides).[6] More efficient fluorination of aliphatic halides can be achieved with a combination of crown ether and bulky diols in acetonitrile solvent.[8] Like other sources of the fluoride ion, F−, KF is poisonous, although lethal doses approach gram levels for humans.