Cyanation of aryl bromides with K4[Fe(CN)6] using polydopamine supported Pd nanoparticle catalysis: formation of magnetite during the reaction

We report the application of polydopamine (PDA) supported Pd nanoparticles in the cyanation of aryl halides with inexpensive and non-toxic K-4[Fe(CN)(6)]. We found that Pd/PDA is an efficient catalyst in the reaction of electron poor aryl halides, however, in other cases the addition of tetrabutyl ammonium bromide was necessary for conversion. The main limitation of the system is suggested to be catalyst deactivation due to Pd aggregation, polymer degradation/functionalization under the high temperature required for catalysis. In several cases we found the formation of magnetite upon reaction, suggesting that K-4[Fe(CN)(6)] is giving away all its six CN groups in cyanation reaction.