white crystals or powder
Sodium tetrafluoroborate is an organic compound that has the molecular formula NaBF4. The compound is a salt that forms white or colorless water-soluble rhombic crystals. It is less soluble in organic solvents and readily soluble in water.
Fluorinating agent, see Lawton, Levy, J. Am. Chem. Soc. 77, 6083 (1955).
Sodium tetrafluoroborate can be prepared by reacting tetrafluoroboric with sodium carbonate or hydroxide.
NaOH + HBF4 → NaBF4 + H2O
Na2CO3 + 2 HBF4 → 2 NaBF4 + H2O + CO2
Sodium tetrafluoroborate can be used as a catalyst for the synthesis of bis(indolyl)methanes via electrophilic substitution reaction of indoles with ketones and aldehydes. In the synthesis of ionic liquids such as trihexyl(tetradecyl)phosphonium tetrafluoroborat and 1-butyl-3-methylimidazolium tetrafluoroborate.
In the laboratory, sodium tetrafluoroborate may be used for the synthesis of boron fluoride. It may also be used in the synthesis of fluoroheterocyclic and fluoro-nucleic acids. The compound is also used in metal finishing, fluxes, and plating circuits.
Crystallise the fluoroborate from hot water (50mL/g) by cooling to 0o. Alternatively, free it from insoluble material by dissolving it in a minimum amount of water; then fluoride ions are removed by adding concentrated lanthanum nitrate in excess. After removing lanthanum fluoride by centrifugation, the supernatant is passed through a cation-exchange column (Dowex 50, Na+-form) to remove any remaining lanthanum [Anbar & Guttman J Phys Chem 64 1896 1960]. It has also been recrystallised from anhydrous MeOH and dried in a vacuum at 70o for 16hours. Keep it dry as it is hygrosopic. [Delville et al. J Am Chem Soc 109 7293 1987.]