Caesium fluoride

Caesium fluoride (cesium fluoride in North America), is an ionic compound usually found as a hygroscopic white solid. It is more soluble and more readily dissociated than sodium fluoride or potassium fluoride. CsF is commercially available—on a lab scale it costs around $50 per 100 g (Synquest), cheaper than RbF. It is available in anhydrous form, and if water has been absorbed it is easy to dry by heating at 100 °C for two hours in vacuo. It is therefore a useful, less hygroscopic alternative to tetra-n-butylammonium fluoride (TBAF) and TAS-fluoride (TASF) when anhydrous "naked" fluoride ion is needed. Like all soluble fluorides, it is mildly basic. Contact with acid should be avoided, as this forms highly toxic/corrosive hydrofluoric acid.