Cyanation of aryl halides

There are several methods available for the cyanation of aryl halides. However, a common problem with many of the more traditional methods is that they are very toxic# One method to full fill these criteria has been around for a while (Weissman S A et al., J. Org. Chem.2005, 70, 1508-1510.)

  Figure: Ligand-free, palladium-catalyzed cyanation of aryl halides. 

Potassium hexacyanoferrate(II) has been used as a cyanide source. This result increases the list of metal-catalyzed reactions that can be performed without ligand.

This method's advantage is obvious; in contrast to other cyanating agents, potassium hexacyanoferrate(II) is less poisonous# and can be handle without special precaution due to the slow release of cyanide ions. Additionally, it significantly improved catalytic productivity compared to know procedures achieved previously.

#( KCN is extremely toxic (LDL0(oral, human) =2.86mg Kg-1 and develop HCN on contract with acidic water. K4[Fe(CN)6]­ is non-toxic and used in the food industry for metal precipitation in wine. Also, it has been used as an anti-agglutinating auxiliary for NaCl (table salt). It is soluble in water without decomposition. Schareina T et al, Chem Commun., 2004, 1388-1389.)