Dehydrogenative Oxidation of Alcohols by Reusable Iridium Catalysts with a Cooperative Polymer Ligand

A series of iridium-polymer complexes containing bipyridonate moieties were synthesized. The high catalytic performance of the iridium-polymer complex for the dehydrogenative oxidation of alcohols was demonstrated. Notably, the bipyridonate moiety in the polymer structure acts as a chemically non-innocent "functional ligand", realizing the enhancement of dehydrogenation process. While numerous metal-polymer catalysts have been reported so far, to our knowledge, introducing a "functional ligand" into a polymer chain that can operate cooperatively with transition metals by changing their structures during the catalytic processes is rare. The iridium-polymer complex could be easily separated from the product and recovered by precipitation upon the addition of methanol after the catalytic reaction. Furthermore, the recovered catalyst could be reused without loss of catalytic efficiency at least ten times. High catalytic performance of the iridium-polymer complex for the dehydrogenative oxidation of alcohols was demonstrated. Bipyridonate moiety in the polymer structure acts as a cooperative "functional ligand", realizing the enhancement of dehydrogenation of various alcohols. Further, recovered catalyst could be reused without loss of catalytic efficiency at least ten times. image