What is "gattermann reaction"

The Gattermann reaction, (also known as the Gattermann aldehyde synthesis) is a chemical reaction in which aromatic compounds are formylated by hydrogen cyanide in the presence of a Friedel–Crafts catalyst (e.g. AlCl). 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/AlCl combination with zinc cyanide. Although it is also highly toxic, Zn(CN) is a solid, making it safer to work with than gaseous HCN; additionally, because the reaction uses HCl, Zn(CN) also supplies the reaction with ZnCl in-situ, where it acts as a Lewis acid catalyst. Examples of Zn(CN) being used in this way include the synthesis of 2-Hydroxy-1-nafthaldehyde and Mesitaldehyde.