Selective ruthenium-catalyzed hydration of nitriles to amides in pure aqueous medium under neutral conditions

A study was conducted to demonstrate that water-soluble ruthenium(II) complexes can be used as catalysts for the hydration of nitriles in pure aqueous media and under neutral conditions. The hydration of benzonitrile was investigated as a model reaction and the ruthenium precursor was added to a 0.33M aqueous solution of benzonitrile at 100°C, while the reaction was monitored by gas chromatography. All the complexes checked, were found to be active and selective catalysts in the hydration process, providing benzamide as a specific reaction product. The most relevant results were obtained by using ruthenium complexes, bearing a nitrogen-containing ligand, which led to appropriate production of benzamide. The most effective ruthenium complex was found to be an efficient catalyst for the selective hydration of a large number of other nitriles.