Boron trifuloride is obtained by the treatment of calcium fluoride with boron trioxide in presence of conc. sulphuric acid.
It can also be obtained by treating boron trioxide with carbon and fluorine.
B2O3 + 3C + 3F2 → 2BF3 + 3CO
In the laboratory pure BF3 is prepared by the thermal decomposition of benzene diazonium tetrafluoro borate.
Boron trifluoride has a planar geometry. It is an electron deficient compound and accepts electron pairs to form coordinate covalent bonds. They form complex of the type [BX4]-.
BF3 + NH3 → F3 ← B NH3
BF3 + H2O → F3B ← OH2
On hydrolysis, boric acid is obtained. This then gets converted into fluoro boric acid.
· Boron trifluoride is used for preparing HBF4, a catalyst in organic chemistry
· It is also used as a fluorinating reagent.