Benzenediazonium tetrafluoroborate is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...

₆H₅N₂F₄. It is a salt of a diazonium cation and

tetrafluoroborate Tetrafluoroborate is the anion . This tetrahedral species is isoelectronic with tetrafluoroberyllate (), tetrafluoromethane (CF4), and tetrafluoroammonium () and is valence isoelectronic with many stable and important species including the perchl ...

. It exists as a colourless solid that is soluble in polar solvents. It is the parent member of the aryl

diazonium compound Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. General propert ...

s, which are widely used in organic chemistry.

Synthesis

Diazotization Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. General properti ...

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine In organic chemistry, an aromatic amine is an organic compound consisting of an aroma ...

in the presence of hydrochloric acid: : C₆H₅NH₂ + HNO₂ + HCl → ₆H₅N₂l + 2 H₂O The tetrafluoroborate can be obtained from crude benzenediazonium chloride by salt metathesis using

tetrafluoroboric acid Fluoroboric acid or tetrafluoroboric acid (archaically, fluoboric acid) is an inorganic compound with the chemical formula +BF4−], where H+ represents the solvated proton. The solvent can be any suitably Lewis-basic entity. For instance, in w ...

. : 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 reaction A name reaction is a chemical reaction named after its discoverers or developers. Among the tens of thousands of organic reactions that are known, hundreds of such reactions are well-known enough to be named after people. Well-known examples include ...

s including the

Schiemann reaction Schiemann is a surname. Notable people with the surname include: * Elisabeth Schiemann (1881–1972), German geneticist, crop researcher and resistance fighter in the Third Reich * Konrad Schiemann, PC (born 1937), British barrister and judge *Paul ...

Sandmeyer reaction The Sandmeyer reaction is a chemical reaction used to synthesize aryl halides from aryl diazonium salts using copper salts as reagents or catalysts. It is an example of a radical-nucleophilic aromatic substitution. The Sandmeyer reaction provides ...

, 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. The reaction of phenyldiazonium salts with aniline gives

1,3-diphenyltriazene 1,3-Diphenyltriazene is the organic compound with the formula PhN=N-N(H)Ph (Ph = C6H5). It is a prototypical triazene, i.e. a compound with the functional group RN=N-NR2. It is a pale yellow solid, prepared by the reaction of phenyldiazonium sa ...

. The structure of the salt has been verified by

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

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

Safety

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

References

{{Reflist Benzene derivatives Diazo compounds Tetrafluoroborates Phenyl compounds