Rosenmund–von Braun reaction

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Rosenmund–von Braun reaction

The Rosenmund–von Braun synthesis is an organic reaction that converts an aryl halide into an aryl nitrile using cuprous cyanide (CuCN).

History: It was discovered in 1914 by Karl Wilhelm Rosenmund and his PhD student Erich Struck. They found that an aryl halide reacts with an alcohol–water solution of potassium cyanide in the presence of catalytic CuCN at about 200 °C. Interestingly, this setup produced the carboxylic acid rather than the nitrile, but Rosenmund suspected the nitrile was the intermediate since nitriles on aromatic rings can become carboxylic acids.

Improvements: Alfred Pongratz and Julius von Braun independently improved the reaction by using higher temperatures and carrying out the reaction without solvent.

Later developments: Over the years, the method was further enhanced, for example by using ionic liquids as solvents.