Catalysis of Organic..

Nikoshvili et al . 179Experimental SectionCatalysts on the Basis of Amphiphylic Block-Copolymers.Amphiphylic PEO-b-P2VP and PS-b-P4VP synthesized by the living anionpolymerization were purchased from Polymer Source Inc., Canada, and Max PlanckInstitute, Germany, respectively. PEO-b-P2VP has the following properties: M n PEО =15400, М nP2VP= 14100, D = 1.04. The molecular structure of PEO-b-PVP is shownin Fig. 2 (a). The structure of PS-b-P4VP, which has the following properties: M n =22500, N nP4VP= 0,340, D = 1.02, is presented in Fig. 2 (b).OnN(a)mn(b)NmFigure 2. Molecular structures of PEO-b-P2VP (a) and PS-P4VP (b)Palladium containing homogeneous polymeric catalysts PEO-b-P2VP and PS-b-P4VP were synthesized by the immobilization of appropriate palladium salts intovinyl pyridine cores of PEO-b-P2VP and PS-b-P4VP micelles, respectively,followed by the reduction of the palladium.Bimetallic colloids (Pd-Au, Pd-Pt and Pd-Zn) stabilized into the micelle coresof PS-b-P4VP were investigated to determine the influence of the second metal (18).In this case, during the preparation of the catalyst, the addition of both metals saltsoccurs simultaneously, followed by reduction of metal compounds.Pd-PEO-P2VP/Al 2 O 3 was studied as a heterogeneous catalyst. To obtain such asystem palladium-containing PEO-P2VP was deposited on γ-Al 2 O 3 by theimpregnation method. Al 2 O 3 was dried at 320 o C for 2.5 h.; after cooling, the micellarsolution of block-copolymer containing Pd colloids was added. The resulting mixturewas stirred for 2-3 days at room temperature. The catalyst was filtered, washed withpetroleum ether and dried in vacuum over P 2 O 5 for 2 days.Catalysts on the Basis of Polymeric Matrices.Polymeric matrices such as HPS allow to control the nucleation and growth of theparticles by the existence of nanosized voids with the high degree of monodispersion(6). The structure of HPS is presented in Fig. 3.