III International Conference

PP-I-50DENDRIMER BASED CATALYSTS IN WACKER-OXIDATION: UNEXPECTEDSELECTIVITY TO TERMINAL DOUBLE BONDSSkorkin V.A., Karakhanov E.A., Kardashev S.V., Maksimov A.L.Moscow State University, Department of Chemistry, Moscow, RussiaE-mail: Skorkinvitaliy@rambler.ruThe esthetically appealing structures of dendrimers have attracted the interest from manydifferent disciplines of science. We demonstrated the unusual change of substrate and processselectivity of catalytic system Pd(II)/Cu(II)/dendrimer based on polypropyleneimine anddifferent diaminoalkanes with terminal nitrile groups for different linear and aromatic olefins.This catalytical system can be easy recycled.The selectivity to the reaction product plays a key role in minimizing of wastes. A smartway to improve selectivity is design of ligands able to bind and orientate substrate due tosupramolecule interaction such as cyclodextrins, calixarenes and dendrimers (a polymers havinga regular branched structure). Dendrimers are characterized by a well-defined highly branchedarchitecture that is obtained via step-wise addition of a number of layers of branched segmentsto a multifunctional core. They are able to bind guest molecules and might be considered asnanosized macromolecular carriers. Dendrimers were shown to improve selectivity for certainreactions depending on the number of branches in the dendrimer molecule.In the present paper we demonstrated the unusual change of substrate and processselectivity of catalytic system Pd(II)/Cu(II)/ dendrimer based on polypropyleneimine anddifferent diaminoalkanes with terminal nitrile groups (PPI (CN) 4 –G0.5; PPI (CN) 8 - G1.5; PPI(CN) 16 -G2.5).Various linear and aromatic 1-alkenes, styrene, cyclohexene, allylbenzene were taken assubstrates. The reaction products were the corresponding ketones, along with the formation ofwhich the isomerization of the double bond was also observed (more than 90 % of alkene-1after 5 min). If dendrimer is absent or the reaction is performed in a homogeneous system, theselectivity with respect to methyl ketone is low (50%). If the reaction is carried out in a twophasesystem in the presence of dendrimer, the process selectivity changes. The results of ourexperiments on the oxidation of C 7 –C 16 alkenes show that, when the ligand is the dendrimermolecule, the fraction of forming methyl ketones substantially increases for the substrates C 7 –C 10 . Also with an increase in the generation from G0.5 to G2.5, the fraction of methyl ketoneswith respect to isomeric ketones increased by a factor of more than two. It was shown, thatreaction rate is affected by the positions of double bond in substrate: in the case of dendrimersthe marked rate was observed only in the case of alkene-1.99