Sandmeyer’s reaction involves treating a primary aromatic amine with sodium nitrite in cold aqueous mineral acid to form a diazonium salt. Mixing the diazonium salt with cuprous chloride or cuprous bromide replaces the diazonium group by –Cl or –Br. For iodination, shaking the diazonium salt with potassium iodide is sufficient, and no cuprous halide is required.
Describe the Sandmeyer’s reaction for the preparation of aryl halides from amines. What conditions and reagents are involved in this reaction?
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Sandmeyer’s reaction is a method for preparing aryl halides from amines. In this reaction, an amine is treated with sodium nitrite (NaNO2) in the presence of hydrochloric acid (HCl) or hydrobromic acid (HBr) at low temperatures. The diazonium salt intermediate formed undergoes substitution reactions with various nucleophiles, such as copper(I) halides (CuX), to yield aryl halides. For example, with CuCl, the reaction produces aryl chlorides. The Sandmeyer’s reaction provides a versatile route for introducing halogen substituents onto aromatic rings, enabling the synthesis of diverse aryl halides with different substituents.