Poly(propylene imine) dendrimer complexes as catalysts for oxidation of alkenes

Complexes of poly(propylene imine) dendrimers D8[DAB-dendr-(NH2)8] and D32 [DAB-dendr-(NH2)32] were prepared by interaction of the dendrimers with transition metal salts such as FeCl3.6H2O; CoCl2.6H2O; CuCl2.2H2O; VOSO4.5H2O; Na2MoO4.2H2O and Na2WO4.2H2O at room temperature in aqueous solutions. The content of metal ions in the complexes was found to be from 8.2 to 69.6 mg metal ion/g polymer carrier. The complexes were characterized by using IR, UV–VIS, Moessbauer spectroscopy and EPR. The anticipated co-ordination structure of the compounds was suggested. It was found that the order of the catalytic activity of the complexes of poly(propylene imine) dendrimers D8 and D32 in the reaction of epoxidation of cyclohexene with organic hydroperoxides such as tert-butyl hydroperoxide (t-BHP), ethylbenzene hydroperoxide (EBHP) and cumene hydroperoxide (CHP) was as follows: D32-MoО22+>D32-VО2+>D32-WО22+ > D32-Co2+ > D32-Cu2+>D32-Fe3+. The order of reactivity of organic hydroperoxides in the reaction studied was: t-BHP > EBHP > CHP.