Ullmann reaction

Under the Ullmann reaction or Ullmann coupling means the coupling of an aromatic halide with a nucleophile or an aromatic halide using a copper powder. It is named after Fritz Ullmann (1875 - 1939).

Overview reaction

In the Ullmann reaction, two aryl halides - in the example, two molecules of chlorobenzene - linked:

By the clutch biphenyl results.

General aryl halides (Ar - Hal) are coupled to biaryls (Ar - Ar). Starting from a mixture of two different aryl halides ( Ar1 - Ar2 - Hal and Hal) also biaryls of type Ar1 - Ar2 can develop in a crossed Ullmann reaction.

Representation

The preparation of biaryls (eg biphenyl ) of aromatic halides using copper powder takes place at about 200 ° C.

Other preparative methods for biaryl: