Catalytic colloidal Pd dispersions in water-organic solutions of quaternary ammonium salt

Colloidal Pd prepared in a water-organic microemulsion in the presence of the cationic surfactant aliquat 336 (trioctylmethylammonium chloride) is useful for the transfer hydrogenolysis of bromotoluene with sodium formate. The Pd catalytic activity is strongly dependent on the particle dimension, being highest for the smallest particles. The size of the particles is determined by the preparation conditions: coarser particles are formed at higher water contents and lower temperatures. The reaction obeys the mechanism of micellar catalysis. (C) 1997 Elsevier Science B.V.