Ullmann Reaction


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Ullmann reaction

[′əl·mən rē‚ak·shən]
(organic chemistry)
A variation of the Fittig synthesis, using copper powder instead of sodium.

Ullmann Reaction

 

a method of obtaining binuclear and polynuclear aromatic compounds by heating aryl halides (ArX, where X = CI, Br, I) at 100°-360°C with powdered copper. One example of the Ullmann reaction is the synthesis of diphenyl from iodobenzene:

2C6H5I + Cu → C6H5 - C6H5 + Cul2

Iodine derivatives enter into the Ullmann reaction more readily. An increased yield is made possible by the activation of copper, for example, with iodine in acetone, and by the application of a solvent—dimethylformamide. It is assumed that the Ullmann reaction proceeds according to a free-radical mechanism. Discovered by F. Ullmann in 1896, the reaction is used, for example, in the manufacture of vat dyes.

References in periodicals archive ?
Ullmann Reaction and the Optimization of Hierarchical Polymerization.
Choosing noble metal for Ullmann reaction is a distinctive characteristic.
This novel way of sequential coupling through Ullmann reaction was applied on 5,15-bis(4'-bromophenyl)-10,20-bis(4'-iodophenyl)porphyrin (trans-[Br.sub.2][I.sub.2]TPP) molecules leading to 2D nanoporous materials (Figure 1) [6].
Through the analysis of a series of factors related to the experiment of Ullmann reaction, the structural quality of covalent networks obtained by kinetically controlled coupling reactions can be improved by optimization of reaction parameters.
Optimization of Hierarchical Polymerization Combined with Ullmann Reaction. To date, the methodology of the bottom-up synthetic method depending on Ullmann coupling has been well-developed.
In addition, the halogen atoms spilt from monomers in the process of Ullmann reaction are still a serious problem that hinders the long-range ordered nanostructure formed on the metal surface.
The N-aryl anthranilic acid derivatives (compound- ii) was obtained starting from O-chlorobenzoic acid with different P-substituted aniline via Ullmann reaction.