Heptane‐soluble homogeneous zirconocene catalyst: Synthesis of a single diastereomer, polymerization catalysis, and effect of silica supports

摘要: Bis(1-indenyl)-di[(1'S, 2'R, 5'S)-menthoxy]silane (1) was converted into a mixture of corresponding ansa-diastereomeric zirconocenes. Further purification afforded single diastereomer, di[(1'S, 5'S)-menthoxy]silylene-bis[η 5 -1(R, R)-(+)-indenyl]dichlorozirconium (2), which is optically active and hydrocarbon soluble. Extremely rapid ethylene, propylene, ethylene-hexene polymerizations were observed both in toluene n-heptane solutions ; for instance, at 50°C, activity ethylene polymerization reaches ∼ 1.5 X 10 (g PE/((mol Zr). [C 2 H 4 ]. h). The bare zirconocenium ion generated from 2/TIBA/Ph 3 CB(C 6 F ) exhibits unusual behaviors the increases monotonically with temperature (T p up to conventional condition (50-70°C), 13 C NMR study shows that isotactic polypropylene obtained has fairly high [mmmm] methyl pentad distributions T (> 25°C 0.93-0.75) perfect stereoregularity low (≤ 0°C > 0.99). catalyst precursors Et(Ind) ZrCl (3) supported on silica by different approaches produced poly(olefins) molecular weights stereoregularities, methylaluminokane Ph free silica-supported zirconocene system found be activated triisobutylaluminum.