Sodium tetrafluoroborate is an inorganic compound with formula NaBF4. It is a salt that forms colorless or white water-soluble rhombic crystals and is soluble in water (108 g/100 mL) but less soluble in organic solvents.[1]
Sodium tetrafluoroborate is used in some fluxes used for brazing and to produce boron trifluoride.[2]
Sodium tetrafluoroborate can be prepared by neutralizing tetrafluoroboric acid with sodium carbonate or sodium hydroxide.[3]
NaOH + HBF4 → NaBF4 + H2O
Na2CO3 + 2 HBF4 → 2 NaBF4 + H2O + CO2
Alternatively the chemical can be synthesized from boric acid, hydrofluoric acid, and sodium carbonate:
2H3BO3 + 8HF + Na2CO3 → 2NaBF4 + 7H2O + CO2
On heating to its melting point, sodium tetrafluoroborate decomposes to sodium fluoride and boron trifluoride:[4]
NaBF4 → NaF + BF3It is a source of tetrafluoroborate anion, which is used in organic chemistry for the preparation of salts. Sodium tetrafluoroborate can be used for synthesis of ionic liquids, where tetrafluoroborate is the anion.