Potassium tetrafluoroborate

Potassium tetrafluoroborate

Names
IUPAC name Potassium tetrafluoroborate
Other names Potassium borofluoride Potassium tetrafluoridoborate Borate(1-), tetrafluoro-, potassium (1:1)
Identifiers
CAS Number	14075-53-7  Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3188573
ChemSpider	24637  Y
ECHA InfoCard	100.034.466
EC Number	237-928-2
PubChem CID	518872
UNII	7D7045L690
CompTox Dashboard (EPA)	DTXSID6037015
InChI InChI=1S/BF4.K/c2-1(3,4)5;/q-1;+1 Key: AKEBROIVCDHVSD-UHFFFAOYSA-N
SMILES [B-](F)(F)(F)F.[K+]
Properties
Chemical formula	K[BF4]
Molar mass	125.90 g·mol−1
Appearance	white crystalline powder
Odor	odorless
Density	2.5 g/mL
Melting point	529.5 °C (985.1 °F; 802.6 K)
Boiling point	decomposes
Solubility in water	0.45g/100g
Solubility in boiling alcohol	sightly soluble
Related compounds
Other anions	Potassium tetrahydroborate
Other cations	Lithium tetrafluoroborate Sodium tetrafluoroborate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Potassium tetrafluoroborate is an inorganic compound with the formula KBF₄. It is a white, odorless crystalline powder, and crystallizes into orthorhombic space group Pbnm. ^[1]

Potassium tetrafluoroborate has been reacted with molten lithium chloride, sodium chloride, and potassium chloride. ^[2] Lithium ions cause the decomposition of tetrafluoroborate leading to the production of BCl₃ gas. The other liquid alkali chlorides do not decompose the tetrafluoroborate, even though they are at higher temperatures. ^[2]

Preparation

Potassium fluoroborate is obtained by treating potassium carbonate with boric acid and hydrofluoric acid.

B(OH)₃ + 4 HF → HBF₄ + 3 H₂O

2 HBF₄ + K₂CO₃ → 2 KBF₄ + H₂CO₃

References

1. Clark, M. J. R.; Lynton, H. (July 1969). "Crystal structures of potassium, ammonium, rubidium, and cesium tetrafluoborates". Canadian Journal of Chemistry. 47 (14): 2579–2586. doi:10.1139/v69-426 . Retrieved 29 July 2025.
2. Danek, V.; Votava, I.; Matiasovsky, K. (1976). "Reactions of potassium tetrafluoroborate in molten alkali chlorides" (PDF). Chem. Zvesti. 30 (3): 377–383. Retrieved 29 July 2025.