Diazotization reaction, also known as diazotization, is a chemical reaction that involves the conversion of a primary aromatic amine (containing an -NH2 group attached to an aromatic ring) into a diazonium salt. This reaction is achieved by treating the primary aromatic amine with sodium nitrite (NaNO2) in the presence of an acid, typically hydrochloric acid (HCl). The diazotization reaction proceeds through several steps: Formation of Nitrous Acid: In the presence of an acid, sodium nitrite (NaNO2) reacts with water (H2O) to produce nitrous acid (HNO2): NaNO2 + HCl → HNO2 + NaCl Diazotization: The nitrous acid then reacts with the primary aromatic amine (Ar-NH2) to form a diazonium salt (Ar-N2+X-), where X represents the counterion, usually chloride (Cl-) or tetrafluoroborate (BF4-): HNO2 + Ar-NH2 → Ar-N2+X- + 2H2O Isolation and Utilization: The diazonium salt is typically isolated as a solid or used directly in further reactions. Diazonium salts are versatile intermediates and can undergo various reactions, including coupling reactions, diazo-coupling reactions, and other substitution reactions, to produce a wide range of organic compounds, such as azo dyes, aromatic compounds, and pharmaceuticals. Diazotization reactions have significant importance in organic synthesis and the preparation of various organic compounds. The resulting diazonium salts are highly reactive and can be used for the introduction of functional groups onto aromatic rings, leading to the synthesis of diverse organic molecules. Additionally, diazonium salts can undergo reactions like Sandmeyer reactions, Schiemann reactions, and Gomberg-Bachmann reactions, which further expand their synthetic utility.