Sandmeyer reaction

Schematic of the Sandmeyer reaction. Reagents: diazonium salt, copper halide catalyst (CuCl, CuBr, CuCN). Product: aryl halide.

The Sandmeyer reaction is an organic reaction used to convert an aryl diazonium salt to an aryl halide using a copper(I) halide catalyst. The mechanism begins with a single electron transfer (SET) from the copper to the diazonium to form a neutral diaso radical and copper(II) halide. The diazo radical then releases a molecule of nitrogen gas to form an aryl radical. The aryl radical reacts with the copper(II) halide to regenerate the copper(I) halide catalyst and yield the final aryl halide product.[1][2]


Mechanism of the Sandmeyer reaction. Sandmeyer Reaction Catalytic Cycle steps include a single electron transfer (SET), diazonium radical formation, and aryl radical formation.


Sandmeyer, T. Ber. Dtsch. Chem. Ges. 1884, 17, 1633–1635.
Sandmeyer, T. Ber. Dtsch. Chem. Ges. 1884, 17, 2650–2653.