Benzenediazonium tetrafluoroborate is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula ₆H₅N₂F₄. It is a salt of a diazonium cation and tetrafluoroborate. It exists as a colourless solid that is soluble in polar solvents. It is the parent member of the aryl diazonium compounds, which are widely used in organic chemistry.

Synthesis

Diazotization of aniline: : C₆H₅NH₂ + HNO₂ (from NaNO₂ and HCl) + HCl → ₆H₅N₂l + 2 H₂O The tetrafluoroborate can be obtained from crude benzenediazonium chloride by salt metathesis using tetrafluoroboric acid. : ₆H₅N₂l + HBF₄ → ₆H₅N₂F₄ + HCl The tetrafluoroborate is more stable than the chloride.

Properties

The diazo group (N₂) can be replaced by many other groups, usually anions, giving a variety of substituted phenyl derivatives: :C₆H₅N₂⁺ + Nu⁻ → C₆H₅Nu + N₂ These transformations are associated with many named reactions including the Schiemann reaction, Sandmeyer reaction, and Gomberg–Bachmann reaction. A wide range of groups that can be used to replace N₂ including halide, SH⁻, CO₂H⁻, OH⁻. Of considerable practical value in the dye industry are the diazo coupling reactions. Reaction with aniline gives 1,3-diphenyltriazene. The structure of the salt has been verified by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

. The N-N bond distance is 1.083(3) Å.

Safety

Whereas the chloride salt is explosive, the tetrafluoroborate is readily isolated.

References

{{Reflist Diazo compounds Tetrafluoroborates Phenyl compounds