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 center dot 6H(2)O; COCl2 center dot 6H(2)O; CuCl2 center dot 2H(2)O; VOSO4 center dot 5H(2)O; Na2MoO4 center dot 2H(2)O and Na2WO4 center dot 2H(2)O 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-MoO22+>D32-VO2+>D32-WO22+ > D32-Co2+ > D32-Cu2+>D32-Fe3+. The order of reactivity of organic hydroperoxides in the reaction studied was: t-BHP > EBHP > CHP. (C) 2009 Elsevier Ltd. All rights resmed.