Gattermann-Koch reaction
The Gattermann reaction, (also known as the Gattermann salicylaldehyde synthesis) is a chemical reaction in which aromatic compounds are formylated by hydrogen cyanide in the presence of a Friedel–Crafts catalyst (e.g. AlCl3). It is named for the German chemist Ludwig Gattermann and is similar to the Friedel-Crafts reaction.
The reaction can be simplified by replacing the HCN/AlCl3 combination with zinc cyanide. Although it is also highly toxic, Zn(CN)2 is a solid, making it safer to work with than gaseous HCN; additionally, because the reaction uses HCl, Zn(CN)2 also supplies the reaction with ZnCl2 in-situ, where it acts as a Lewis acid catalyst. Examples of Zn(CN)2 being used in this way include the synthesis of 2-Hydroxy-1-nafthaldehyde and Mesitaldehyde.
The Gattermann–Koch reaction, named after the German chemists Ludwig Gattermann and Julius Arnold Koch, refers to a Friedel–Crafts acylation reaction in which carbon monoxide, hydrochloric acid, and a Friedel–Crafts catalyst (e.g. AlCl3) are used to produce aromatic aldehydes from various aromatic compounds, including derivatives of benzene and naphthalene:
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