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Stereospecificity of propene polymerization with achiral titanocene‐based catalysts
Author(s) -
Hagihara Hideaki,
Shiono Takeshi,
Ikeda Tomiki
Publication year - 1998
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19981101)199:11<2439::aid-macp2439>3.0.co;2-4
Subject(s) - propene , polymerization , toluene , stereospecificity , chemistry , polymer chemistry , catalysis , solvent , tacticity , metallocene , polymer , organic chemistry
Propene polymerization was conducted with titanocene (Cp 2 TiMe 2 , Cp 2 * TiMe 2 ; Cp = η 5 ‐C 5 H 5 , Cp * = η 5 ‐C 5 Me 5 )/organoborane (B(C 6 F 5 ) 3 , Ph 3 CB(C 6 F 5 ) 4 ) catalysts at −50°C using toluene as a solvent. The polymer obtained with Cp 2 TiMe 2 /Ph 3 CB(C 6 F 5 ) 4 is less isotactic than that obtained with Cp 2 TiMe 2 /B(C 6 F 5 ) 3 . However, the isospecificity of the former catalyst is improved with respect to that of the latter one when a toluene/CH 2 Cl 2 mixture is used as a solvent instead of toluene. As similar enhancement in isospecificity was observed when alkylaluminium is added to the polymerization system. On the other hand, only Ph 3 CB(C 6 F 5 ) 4 is an efficient cocatalyst for the propene polymerization with Cp 2 * TiMe 2 . The polymer obtained with Cp 2 * TiMe 2 /Ph 3 CB(C 6 F 5 ) 4 as catalyst is atactic, even in the presence of CH 2 Cl 2 or alkylaluminium. Based on these results, the stereospecificity of achiral titanocenes is discussed.