Ullmann reaction

The Ullmann reaction or Ullmann coupling is the coupling of an aromatic halide with a nucleophile or an aromatic halide with the help of 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 - are linked together:

The coupling creates biphenyl .

In general, aryl halides (Ar – Hal) are coupled to form symmetrical biaryls (Ar – Ar). Starting from a mixture of two different aryl halides (Ar ¹ –Hal and Ar ² –Hal), unsymmetrical biaryls of the Ar ¹ –Ar ² type can also be formed in a crossed Ullmann reaction .

presentation

The preparation of biaryls ( e.g. biphenyl ) from aromatic halides with the help of copper powder takes place at approx. 200 ° C.

Further display options for biaryls:

Individual evidence

^ Z. Wang: Comprehensive Organic Name Reactions and Reagents, 3 Volume Set . John Wiley & Sons, Hoboken, New Jersey 2009, ISBN 978-0-471-70450-8 , p. 2843.

literature

Reinhard Brückner : reaction mechanisms . 3rd edition, Spektrum Akademischer Verlag, Munich 2004, ISBN 3-8274-1579-9 .

[Wang_XXX-1] Z. Wang: Comprehensive Organic Name Reactions and Reagents, 3 Volume Set . John Wiley & Sons, Hoboken, New Jersey 2009, ISBN 978-0-471-70450-8 , p. 2843.