Synthesis of elastomeric polypropylene in bulk using C
1-symmetric ansa-metallocenes. New aspects of the synthesis of 1-(fluoren-9-yl)-2-(2-methyl-5,6-dihydrocyclopenta [f]-1H-inden-1-yl)ethane and complexes of zirconium and hafnium with this ligand |
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Authors: | P M Nedorezova E N Veksler E S Novikova V A Optov A O Baranov A M Aladyshev V I Tsvetkova B F Shklyaruk D P Krut’ko A V Churakov L G Kuz’mina J A K Howard |
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Institution: | (1) N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4 ul. Kosygina, 119991 Moscow, Russian Federation;(2) A. V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, 29 Leninsky prosp., 119991 Moscow, Russian Federation;(3) Department of Chemistry, M. V. Lomonosov Moscow State University, 1 Leninskie Gory, 119992 Moscow, Russian Federation;(4) N. S. Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, 31 Leninsky prosp., 119991 Moscow, Russian Federation;(5) Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE, UK |
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Abstract: | Isomeric 1-(fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta f]-1 H-indenyl) ethanes 1a,b and C
1-symmetric metallocenes, viz., rac-1-(η5-fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta f]-η5-inden-1-yl) ethanezirconium dichloride (9) and rac-1-(η5-fluoren-9-yl)- 2-(2-methyl-5, 6-dihydrocyclopenta f]η5-inden-1-yl)ethanehafnium dichloride (10), with these ligands were synthesized by modified procedures. The structures of compounds 1b (two crystalline modifications) and 10 were established by X-ray diffraction analysis. The synthesis of polypropylene (PP) in bulk was studied in the presence of polymethylalumoxane-activated metallocenes 9 and 10 in the temperature range of 30–70°C. It was demonstrated that triisobutylaluminum can be used as a cocatalyst. In this case, the molecular weight of PP increases by a factor of ∼2. An increase in the reaction temperature leads to an increase in stereoregularity and crystallinity of PP. The polymer synthesized at high temperatures crystallizes in the γ form. The resulting PP is characterized by a wide range of properties from rigid crystalline thermoplastic to amorphous elastomeric. Samples, which have a high molecular weight and moderate isotacticity, exhibit high elastomeric and durability properties.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 400–413, February, 2005. |
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Keywords: | zirconium hafnium C
1-symmetric ansa-metallocenes X-ray diffraction analysis propene polymerization elastomeric polypropylene microstructure phase state |
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