Introduction: 

hexafluorophosphate series is a very important inorganic fluorine salt, among which, ammonium hexafluorophosphate is a more important one of hexafluorophosphate, it can be used to prepare other hexafluorophosphate, is also an important substance to prevent dental caries.

Preparation method: 

Ammonium hexafluorophosphate is fluorinated by ammonium fluoride and phosphorus pentachloride in hydrofluoric acid, or phosphorus pentachloride is mixed with dry ammonium fluoride, heated and cooled, dissolved in water, adding "nitric acid" reagent, forming precipitation, washing with cold water several times, then shaking chloroform and ammonia together, removing "nitric acid" by extraction method, and evaporating on the water bath.