C6H5N2X

C6H5N2X is a chemical formula that represents a class of organic compounds known as diazonium salts. The core structure is a phenyl group (C6H5) attached to a diazonium group (N2+), with a halide ion (X-) as the counterion. The specific identity of the halide ion, such as chloride (Cl-), bromide (Br-), or iodide (I-), determines the exact compound within this class.

These compounds are typically synthesized by the diazotization of primary aromatic amines, such as aniline, using nitrous acid. The reaction is usually carried out at low temperatures, as diazonium salts are generally unstable. The phenyl diazonium ion is a highly reactive species.

Diazonium salts, including those represented by C6H5N2X, are important intermediates in organic synthesis. They readily undergo various reactions, most notably the Sandmeyer reaction, where the diazonium group can be replaced by a wide range of substituents, including halogens, cyanide, and hydroxyl groups, by reaction with appropriate copper salts or other reagents. They can also be used in coupling reactions to form azo compounds, which are often used as dyes. Due to their instability, they are usually prepared and used in situ without isolation.