Polarographic studies of CpTiCl2(OC6H4X-p)/MAO and EPR studies of CpTiCl2(OC6H4X-p)/MAO/styrene systems

Skupiński, Wincenty; Niciński, K.; Maksimowski, Paweł; Wasek, M.

doi:10.1016/s1381-1169(01)00300-4

Cited by 13 publications

(16 citation statements)

References 9 publications

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“…Also, the yield of the syndiotactic polystyrene obtained in the presence of these systems exhibits a proportionality to the donor effects of the X substituent (Table 7) [16].…”

Section: Discussionmentioning

confidence: 98%

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Effect of phenoxy ligands on catalytic properties of titanium half-sandwich complexes/MAO systems

Jamanek¹,

Niciński²,

Kazimierczuk³

et al. 2006

Journal of Molecular Catalysis A: Chemical

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“…Also, the yield of the syndiotactic polystyrene obtained in the presence of these systems exhibits a proportionality to the donor effects of the X substituent (Table 7) [16].…”

Section: Discussionmentioning

confidence: 98%

“…LTiCl 2 (OC 6 H 4 X-p) complexes were prepared by the procedures described in the available literature [13][14][15][16].…”

Section: Methodsmentioning

confidence: 99%

Effect of phenoxy ligands on catalytic properties of titanium half-sandwich complexes/MAO systems

Jamanek¹,

Niciński²,

Kazimierczuk³

et al. 2006

Journal of Molecular Catalysis A: Chemical

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“…An abundant group of theses compounds are some EPRactive Ti[III] hydride complexes. These are produced in the reduction of titanium cyclopentadienyl complexes by typical alkyl-or hydrideorganoaluminum compounds [30,31], and in the reduction with alumoxanes [32,33] as well as boron hydrides [34]. In the spectra of hydride complexes formed in these reactions signals are observed which exhibit exceptionally high g values, close to, or even exceeding, 2 [33,34].…”

Section: Epr Of the Systems Studiedmentioning

confidence: 99%

Study on the NaNp/CpTiCl3/Al2O3–SiO2 system

Maksimowski

Skupiński

2007

Journal of Colloid and Interface Science

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“…Our previous results [15,16] and theoretical considerations [17] indicate that Ti(III) ions are responsible for syndiotactic styrene polymerization in hemititanocene catalytic systems. The theoretical considerations claimed that olefin polymerization runs also in the presence of Ti(IV) ions in these systems [17].…”

Section: Introductionmentioning

confidence: 97%

“…We found that the substituents -X of the phenoxy ligand affect the yield of this reaction. In our previous article [15] it has been reported that the content of titanium ions in various oxidation states depends on the electron donor-acceptor properties of the substituent X (Table 1). As can be seen from Table 1, the content of Ti(III) in the solution decreases, and the content of Ti(IV) rises with the electron acceptor properties of X substituents.…”

Section: Introductionmentioning

confidence: 99%

Homo-polymerization of α-Olefins and Co-polymerization of Higher α-Olefins with Ethylene in the Presence of CpTiCl2(OC6H4X-p)/MAO Catalysts (X = CH3, Cl)

et al. 2005

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Cyclopentadienyl-titanium complexes containing –OC6H4X ligands (X = Cl, CH3) activated with methylaluminoxane (MAO) were used in the homo-polymerization of ethylene, propylene, 1-butene, 1-pentene, 1-butene, and 1-hexene, and also in co-polymerization of ethylene with the α-olefins mentioned. The -X substituents exhibit different electron donor-acceptor properties, which is described by Hammett’s factor (σ). The chlorine atom is electron acceptor, while the methyl group is electron donor. These catalysts allow the preparation of polyethylene in a good yield. Propylene in the presence of the catalysts mentioned dimerizes and oligomerizes to trimers and tetramers at 25°C under normal pressure. If the propylene pressure was increased to 7 atmospheres, CpTiCl2(OC6H4CH3)/MAO catalyst at 25°C gave mixtures with different contents of propylene dimers, trimers and tetramers. At 70°C we obtained only propylene trimer. Using the catalysts with a -OC6H4Cl ligand we obtained atactic polymers with Mw 182,000 g/mol (at 25°C) and 100,000 g/mol (at 70°C). The superior activity of the CpTiCl2(OC6H4Cl)/MAO catalyst used in polymerization of propylene prompted us to check its activity in polymerization of higher α-olefins (1-butene, 1-pentene, 1-hexene) and in co-polymerization of these olefins with ethylene. However, when homo-polymerization was carried out in the presence of this catalyst no polymers were obtained. Gas chromatography analysis revealed the presence of dimers. The activity of the CpTiCl2(OC6H4Cl)/MAO catalyst in the co-polymerization of ethylene with higher α-olefins is limited by the length of the co-monomer carbon chain. Hence, the highest catalyst activities were observed in co-polymerization of ethylene with propylene (here a lower pressure of the reagents and shorter reaction time were applied to obtain catalytic activity similar to that for other co-monomers). For other co-monomers the activity of the catalyst decreases as follows: propylene >1-butene > 1-pentene >> 1-hexene. In the case of co-polymerization of ethylene with propylene, besides an increase in catalytic activity, an increase in the average molecular weight Mw of the polymer was observed. Other co-monomers used in this study caused a decrease of molecular weight. A significant increase in molecular weight distribution (Mw/Mn) evidences a great variety of polymer chains formed during the reaction.

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Polarographic studies of CpTiCl2(OC6H4X-p)/MAO and EPR studies of CpTiCl2(OC6H4X-p)/MAO/styrene systems

Cited by 13 publications

References 9 publications

Effect of phenoxy ligands on catalytic properties of titanium half-sandwich complexes/MAO systems

Effect of phenoxy ligands on catalytic properties of titanium half-sandwich complexes/MAO systems

Study on the NaNp/CpTiCl3/Al2O3–SiO2 system

Homo-polymerization of α-Olefins and Co-polymerization of Higher α-Olefins with Ethylene in the Presence of CpTiCl2(OC6H4X-p)/MAO Catalysts (X = CH3, Cl)

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