Cyanation of aryl halides using potassium hexacyanoferrate() direct mechanocatalysis

A cyanation reaction was performed inside a ball mill system utilizing catalytically active milling balls, while avoiding the use of solvents and ligands. Additionally, replacing the highly toxic cyanide source with potassium hexacyanoferrate( ii ) leads to a safer reaction environment. Yields of up to 90% were achieved in as little as 4 hours at room temperature. The oxidative addition and transmetalation step could be observed via X-ray photoelectron spectroscopy (XPS) and powder X-ray diffraction (PXRD) analysis, respectively, giving a first indication of the mechanism of this mechanochemical reaction. A solvent- and ligand-free cyanation reaction using a catalytically active Pd milling ball and K 4 [Fe(CN) 6 ] as a safer cyanide source achieved up to 90% yield in 4 hours at room temp. Mechanistic steps were observed via XPS and PXRD.