Formula of Diazonium Salt

Diazonium salts are a class of organic compounds with the general formula R-N2+X-. Here, R represents an organic group, and X is an anion such as chloride (Cl-), bromide (Br-), or tetrafluoroborate (BF4-). Diazonium salts are formed by the reaction of primary aromatic amines with nitrous acid (HNO2) under acidic conditions.

Formation of Diazonium Salt

The formation of diazonium salts involves the diazotization reaction, where an amine group (-NH2) is converted into a diazonium group (-N2+). This reaction proceeds via the following steps:
1. Nitrous acid (HNO2) is generated in situ by the reaction of sodium nitrite (NaNO2) with a strong acid like hydrochloric acid (HCl).
2. The amine reacts with nitrous acid to form a diazonium salt, which is stabilized by resonance.
3. The diazonium salt can further react to form various organic compounds such as azo dyes, phenols, and aromatic compounds.

Properties of Diazonium Salts

Diazonium salts are characterized by their instability and reactivity. They are usually kept cold and are sensitive to light and moisture. Diazonium salts are versatile intermediates in organic synthesis, used for various transformations such as coupling reactions, Sandmeyer reactions, and Wolff rearrangements.

In conclusion, the formula of a diazonium salt is R-N2+X-, where R represents an organic group and X is an anion. These compounds are formed through the diazotization reaction of a primary aromatic amine with nitrous acid. Diazonium salts play a crucial role in organic chemistry due to their reactivity and ability to undergo diverse chemical reactions.