Tetrafluoroborate salts are commonly employed as non-coordinating anions. They undergo rapid halide exchange reactions:īecause of the facility of this exchange process, the mixed halides cannot be obtained in pure form.īoron trifluoride is a versatile Lewis acid that forms adducts with such Lewis bases as fluoride and ethers:ĬsF + BF 3 → Cs O(CH 2CH 3) 2 + BF 3 → BF 3 Unlike the aluminium and gallium trihalides, the boron trihalides are all monomeric. The grease used in the equipment should be fluorocarbon based, as boron trifluoride reacts with the hydrocarbon-based ones. Polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, and polypropylene show satisfactory resistance. In presence of moisture it corrodes steel, including stainless steel. Suitable metals for equipment handling boron trifluoride include stainless steel, monel, and hastelloy. Storage or transport vessels should be designed to withstand internal pressure, since a refrigeration system failure could cause pressures to rise to the critical pressure of 49.85 bar (4.985 MPa). A well documented route involves the thermal decomposition of diazonium salts of −: + − → PhF + BF 3 + N 2Īlternatively it arises from the reaction of sodium tetrafluoroborate, boron trioxide, and sulfuric acid: 6 Na + B 2O 3 + 6 H 2SO 4 → 8 BF 3 + 6 NaHSO 4 + 3 H 2O Properties Īnhydrous boron trifluoride has a boiling point of −100.3 ☌ and a critical temperature of −12.3 ☌, so that it can be stored as a refrigerated liquid only between those temperatures. Laboratory routes to the solvent-free materials are numerous.

Laboratory scale įor laboratory scale reactions, BF 3 is usually produced in situ using boron trifluoride etherate, which is a commercially available liquid. Approximately 2300-4500 tonnes of boron trifluoride are produced every year. Typically the HF is produced in situ from sulfuric acid and fluorite ( CaF 2). īF 3 is manufactured by the reaction of boron oxides with hydrogen fluoride: Others point to the ionic nature of the bonds in BF 3. A facile explanation invokes the symmetry-allowed overlap of a p orbital on the boron atom with the in-phase combination of the three similarly oriented p orbitals on fluorine atoms. In the boron trihalides, BX 3, the length of the B–X bonds (1.30 Å) is shorter than would be expected for single bonds, and this shortness may indicate stronger B–X π-bonding in the fluoride. The molecule is isoelectronic with the carbonate anion, CO 2− 3.īF 3 is commonly referred to as ' electron deficient,' a description that is reinforced by its exothermic reactivity toward Lewis bases. The molecule has no dipole moment by virtue of its high symmetry. Its D 3h symmetry conforms with the prediction of VSEPR theory. The geometry of a molecule of BF 3 is trigonal planar. It is a useful Lewis acid and a versatile building block for other boron compounds. This pungent, colourless, and toxic gas forms white fumes in moist air. Boron trifluoride is the inorganic compound with the formula BF 3.

Boron atom bohr model