High Catalytic Efficiency Combined with High Selectivity for the Aldehyde–Water Shift Reaction using (para-cymene)Ruthenium Precatalysts

A family of (para-cymene)­Ru^II complexes are shown to be competent precatalysts for the oxidation of aldehydes to carboxylic acids using water as the oxidant. This reaction, known as the “aldehyde–water shift” (AWS), has been previously demonstrated to be in competition with aldehyde disproportionation. For the few reported mononuclear catalysts for this reaction, either high selectivity for AWS and low conversion or low AWS selectivity and high conversion is observed. A homogeneous precatalyst which is both highly selective for the desired AWS and is highly efficient for conversion of the aldehyde to products is reported herein. In addition, catalyst activity is found to be general to a variety of sterically unencumbered aliphatic aldehydes producing the corresponding carboxylic acid and hydrogen gas.