Selectivity Switch in the Aerobic 1,2‐Propandiol Oxidation Catalyzed by Diamine‐Stabilized Palladium Nanoparticles

Palladium nanoparticles stabilized by a sterically demanding secondary diamine ligand have been synthesized by hydrogen reduction of a palladium acetate complex bearing the corresponding diimine ligand. The obtained nanoparticles were used to catalyze the aerobic oxidation of 1,2‐propandiol in n‐hexane, and after their heterogenization onto a high surface area carbon, in water. In n‐hexane (2,4‐dimethyl‐1,3‐dioxolan‐2‐yl) methanol has been obtained as major product, whereas in water acetic acid with a selectivity of >85 % has been achieved. The selectivity switch observed was a clear induced by water. The robustness of diamine‐stabilized palladium nanoparticles under real aerobic oxidation conditions has been proved by recycling experiments, TEM measurements of the recovered catalysts and by comparison of its performance with that of palladium nanoparticles generated by the metal vapor synthesis technique and supported onto the same carbon in the absence of the stabilizing diamine ligand. Switch it up! Hexane solutions of the diamine‐stabilized palladium nanoparticles efficiently catalyzed the aerobic oxidation of 1,2‐propandiol, giving (2,4‐dimethyl‐1,3‐dioxolan‐2‐yl) methanol as major compound, whereas the same nanoparticles oxidized in water 1,2‐propandiol to acetic acid. The selectivity switch was triggered by water. Selectivity switch in the aerobic 1,2‐propandiol oxidation catalyzed by diamine‐stabilized palladium nanoparticles (Werner Oberhauser CNR‐ICCOM CNR‐ISMN)