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Synthesis of Silylene-Bridged Thiophene-Fused Cyclopentadienyl ansa-Metallocene Complexes for High-Performance Supported Catalyst
- Author(s)
- 정선미
- Advisor
- 이분열
- Department
- 일반대학원 분자과학기술학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2022-02
- Language
- eng
- Keyword
- ethylene polymerization; metallocene catalyst; methylaluminoxane; silica; slurry process; supported catalyst
- Alternative Abstract
- A series of Me2Si-bridged ansa-zirconocene complexes coordinated with thiophene-fused cyclopentadienyl ligand and fluorenyl ligand [Me2Si(2-R1-3-R2-4,5-Me2C7S)(2,7-R32C13H6)]ZrMe2 (9, R1 = Me, R2 = H, R3 = H; 10, R1 = Me, R2 = Me, R3 = H; 11, R1 = H, R2 = H, R3 = H; 12, R1 = Me, R2 = H, R3 = tBu; 13, R1 = Me, R2 = H, R3 = Cl) were synthesized with an aim to prepare a supported catalyst adoptable in a commercial process. Fluorenyl anion is more basic than thiophene-fused cyclopentadienyl, and sequence of reaction order to Me2SiCl2 was crucial to achieve high yield; successive addition of fluorenyl-Li and thiophene-fused cyclopentadienyl-Li to Me2SiCl2 resulted in high yield (87%) while addition in the reverse sequence afforded the ligand precursor in low yield (27%). X-ray crystallography studies of 9 revealed that fluorenyl ligand adopts an 3-binding mode. Related Me2Si-bridged ansa-zirconocene complex 15 was also prepared replacing fluorenyl ligand in 9 with 2-methyl-4-(4-tert-butylphenyl)indenyl ligand, although it was obtained as a mixture of two diastereomers. Furthermore, ansa-metallocene complexes 20 and 23 containing tBuO(CH2)6- were prepared by replacing Me2Si-bridge in 12 and 15 with tBuO(CH2)6(Me)Si-bridge. Silica supported catalysts prepared with 12 showed two times higher productivity than the one prepared with the conventional (THI)ZrCl2 (26 vs. 12 kg-PE/g-(supported catalyst)) with polymers with comparable molecular weight (Mw, 330 vs. 300 kDa) but containing higher amount of 1-hexene content (1.3 and 1.0 mol%) being produced, although the bulk density of generated polymer particles was rather inferior (0.35 vs. 0.42 g/mL).
- Fulltext
- Appears in Collections:
- Graduate School of Ajou University > Department of Molecular Science and Technology > 3. Theses(Master)
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