200009-41-2Relevant academic research and scientific papers
Coordination copolymerization of severely encumbered isoalkenes with ethylene: Enhanced enchainment mediated by binuclear catalysts and cocatalysts
Li, Hongbo,Li, Liting,Schwartz, David J.,Metz, Matthew V.,Marks, Tobin J.,Liable-Sands, Louise,Rheingold, Arnold L.
, p. 14756 - 14768 (2005)
This contribution describes the implementation of the binuclear organotitanium constrained geometry catalysts (CGCs), (μ-CH 2CH2-3,3′){(η5-indenyl)[1-Me 2Si(tBuN)](TiMe2)}2[EBICGC(TiMe 2)2; Ti2] and (μ-CH2-3,3′) {(η5-indenyl)[1-Me2Si(tBuN)](TiMe 2)}2[MBICGC(TiMe2)2; C1-Ti 2], in combination with the bifunctional bisborane activator 1,4-(C6F5)2BC6F4B(C 6F5)2 (BN2) in ethylene + olefin copolymerization processes. Specifically examined are the classically poorly responsive 1,1-disubstituted comonomers, methylenecyclopentane (C), methylenecyclohexane (D), 1,1,2-trisubstituted 2-methyl-2-butene (E), and isobutene (F). For the first three comonomers, this represents the first report of their incorporation into a polyethylene backbone via a coordination polymerization process. C and D are incorporated via a ring-unopened pathway, and E is incorporated via a novel pathway involving 2-methyl-1 -butene enchainment in the copolymer backbone. In ethylene copolymerization, Ti 2 + BN2 enchains ～2.5 times more C, ～2.5 times more D, and ～2.3 times more E than the mononuclear catalyst analogue [1-Me2Si(3-ethylindenyl)-(tBuN)]TiMe2 (Ti 1) + B(C6F5)3 (BN) under identical polymerization conditions. Polar solvents are found to weaken the catalyst-cocatalyst ion pairing, thus influencing the comonomer enchainment selectivity.
Catalyst/cocatalyst nuclearity effects in single-site olefin polymerization. Significantly enhanced 1-octene and isobutene comonomer enchainment in ethylene polymerizations mediated by binuclear catalysts and cocatalysts
Li, Hongbo,Li, Liting,Marks, Tobin J.,Liable-Sands, Louise,Rheingold, Arnold L.
, p. 10788 - 10789 (2003)
This Communication describes the implementation of a new binuclear homometallic organotitanium constrained geometry catalyst (CGC), (μ-CH2CH2-3,3′){ (η5-indenyl )[1-Me2Si (tBuN)](TiMe2)}2[EBICGC(TiMe2)2; Ti2], together with the bifunctional activators (Ph3C+)2[1,4-(C6F5)3BC6F4B(C6F5)3]2- (B2) and new bisborane 1,4-(C6F5)2BC6F4B(C6F5)2 (BN2) in ethylene + α-olefin copolymerization processes. Specifically examined are the comonomers 1-octene and poorly responsive isobutene. Large increases in comonomer enchainment efficiency into the polyethylene microstructure are observed versus the corresponding mononuclear catalyst [1-Me2Si(3-ethylindenyl)(tBuN)]TiMe2 (Ti1) + Ph3C+B(C6F5)4- (B1) or B(C6F5)3 (BN) under identical polymerization conditions. In ethylene + 1-octene copolymerization, 11 times more 1-octene incorporation is observed for Ti2 + B2 vs Ti1 + B1. In ethylene + isobutene copolymerization, 5 times more isobutene incorporation is observed for Ti2 + BN2 vs Ti1 + BN. Copyright
