What is sandmeyer's reaction?

The substitution of an aromatic amino group is possible via preparation of its diazonium salt and subsequent displacement with a nucleophile (Cl-, I-, CN-, RS-, HO-). Many Sandmeyer Reactions proceed under copper(I) catalysis, while the Sandmeyer-type reactions with thiols, water and potassium iodide don ''t require catalysis.

The Sandmeyer Reaction is a very important transformation in aromatic chemistry, because it can result in some substitution patterns that are not achievable by direct substitution.

Sandmeyer’s Reaction is a reaction used for conversion of diazonium salt to aryl halide.It is applicable to primary aromatic amines.

Step 1: preparation of diazonium salt.

Step 2: Preparation of aryl halide from diazonium salt.

For Cl and Br:

For I:

this reaction consists of treating freshly prepared diazonium salt with cuprous chloride or cuprous bromide. the copper salt is dissolved in the corresponding halogen acids i.e., chloro and bromo arenes

diazonium satls required for this purpose are prepared by treating ice-cold solution of amino derivatives of arenes with excess of dil.HCL and with an aqueous solution of sodium nitrate at low temperature .

this reaction is known as sandmeyer''s reaction.