Synthesis and characterization of dendritic salicylaldimine complexes of copper and cobalt and their use as catalyst precursors in the aerobic hydroxylation of phenol

A series of generation 1 (G1) and generation 2 (G2) salicylaldimine functionalized polypropylene imine dendrimers were used to prepare a range of new copper and cobalt metallodendrimers. These were found to be efficient catalysts in the aerobic hydroxylation of phenol using H2O2 and molecular oxygen as oxidants. The major products obtained were catechol and hydroquinone. The selectivity to these two products was greatly influenced by the nature of the metallodendrimer as well as by the pH of the reaction medium.