Reactivity of Metallocene Catalysts for Olefin Polymerization: Influence of Activator Nature and Structure

Pédeutour, Jean-Noël; Kannan, R. Sayee; Cramail, Henri; Deffieux, Alain

doi:10.1002/1521-3927(20011001)22:14<1095::aid-marc1095>3.0.co;2-r

Cited by 158 publications

(111 citation statements)

References 143 publications

(212 reference statements)

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“…Nucleophilicity, coordinating ability and bulkiness of the cocatalyst affect the activity of the catalyst. [18] Borate anions are less bulky, more polar and have better coordinating ability than MAO. [19] In all the polymerisation experiments with [HNMe 2 Ph][B(C 6 F 5 ) 4 ]/TIBA as a cocatalyst, the initial activity was high, but the catalyst deactivated very fast.…”

Section: The Effect Of Counterionmentioning

confidence: 99%

Effect of Metallocene Structures on their Performance in Ethene Polymerisation

Piel¹,

Saarinen²,

Löfgren³

et al. 2007

Macro Chemistry & Physics

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Six (Cp)(4‐phenyl‐indenyl)MCl2 (A) and four (Cp)(1‐phenyl‐indenyl)MCl2 (C) (M = Zr/Hf) based complexes were tested in ethene homo‐ and copolymerisation under different conditions to explain how the differences in the complex structure affect the polymerisation process and the formed polymer. Polymerisation experiments reveal that hafnocene catalysts need a higher amount of MAO to reach the maximum activity than zirconocenes. Hafnocenes also incorporate better 1‐hexene. Catalysts with the Cp* or 1,2,4‐Me3Cp ligand show higher activity, and work well with [HNMe2Ph][B(C6F5)4]/TIBA as cocatalyst, but produce polymers with lower $\overline M _{\rm n} $ than the corresponding catalyst with a plain Cp ligand. The Cp* ligand seems to prevent 1‐hexene incorporation. A methyl group in the 2‐position of (Cp)(4‐PhInd)ZrCl2 decreases the activity and $\overline M _{\rm n} $ but favours 1‐hexene insertion. Polymerisation activity is higher with catalysts with a 1‐PhInd‐ligand than with a 4‐PhInd‐ligand.magnified image

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Section: The Effect Of Counterionmentioning

confidence: 99%

Effect of Metallocene Structures on their Performance in Ethene Polymerisation

Piel¹,

Saarinen²,

Löfgren³

et al. 2007

Macro Chemistry & Physics

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“…1 H NMR analysis of the reaction products indicates the almost total consumption of TMA for [TMA]/[AA] up to 4, while for ratio > 4, a signal at around À0.3 ppm reveals the presence of free TMA. For [TMA]/[AA] ratio equal to 4, the 1 H NMR spectrum (see Figure 1) shows the presence of two series of signals at 1.2-1.6 ppm and À0.4 to À1.0 ppm that can be attributed, respectively, to the methyl groups of various products derived from AA (II to IV, see Scheme 1) and to the methyl groups of -OAlMe 2 structures, on the basis of previous investigations with BA and TMA.…”

Section: Resultsmentioning

confidence: 99%

“…[1] The MAO used in such reactions is usually synthesized by the controlled hydrolysis of trimethylaluminum (TMA) and presents a cage-like structure with tetra-coordinated aluminum centers exhibiting a latent Lewis acidic character. [2,3] In recent years, a series of studies was carried out in order to develop novel routes to MAO or to find substitutes that could be more efficient towards transition metal derivatives activation.…”

Section: Introductionmentioning

confidence: 99%

Novel Organic Activators for Single Site Iron Catalysts

Tudella

Ribeiro

Cramail

et al. 2007

Macro Chemistry & Physics

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The synthesis of new organo‐aluminum derivatives based on the reaction of carboxylic acids with trialkylaluminum and their use as co‐catalysts for ethylene polymerization, in the presence of iron catalyst is described. These co‐catalysts were obtained through the reaction of acetic acid, benzoic acid, or benzoic acid derivatives with different trialkylaluminums. The most promising co‐catalyst was obtained from the reaction of benzene tricarboxylic acid (BTCA) with trimethylaluminum (TMA). The influence of alkylaluminum/BTCA ratio, reaction time, and temperature on the ethylene polymerization activity was investigated. 1H NMR spectra of some of the most active co‐catalysts confirm the formation of alumoxane‐type species.Polymerization activities of the same order or even higher to those found using “pure” trialkylaluminums or methylaluminoxane (MAO) co‐catalysts were obtained.magnified image

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“…A similar strategy facilitates the interpretation of the NMR spectra due to the fact that active sites (AS) of polymerization are formed in these systems already at the stoichiometric zirconocene/activator ratio [9] unlike the systems containing methylaluminoxane (MAO) as an activator. However, the majority of the most active and promising for industrial use catalytic systems contain just MAO, viz., the product of incomplete hydrolysis of trimethylaluminum, the structure and role of which in the formation of AS of the polymerization of ethylene and olefins have not been established so far [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…Later, the study of the NMR spectra of the Cp 2 ZrMe 2 -MAO and Cp 2 ZrCl 2 -MAO systems [23] made it possible to reliably detect heterobinuclear species (III), the formation of which involves, most likely, trimethylaluminum from MAO [10]. According to the data obtained [23], the amount of species (III) increases with an increase in the Al/Zr molar ratio in the catalytic system and is accompanied by an increase in the activity of the system in the course of polymerization.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of the interaction of components in the metallocene catalytic systems containing titanium and zirconium tetracyclopentadienyls and methylaluminoxane

Седов

Matkovskiy

Кнерельман

et al. 2016

Reac Kinet Mech Cat

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The reactions of components of the catalytic systems (C 5 H 5 ) 4 Zr-MAO and (C 5 H 5 ) 4 Ti-MAO in the absence and in the presence of the monomer were studied in order to obtain information on the mechanism of polymerization and copolymerization of ethylene. It was shown that the reactions accompanied by a change in the coordination mode of the ligands in the metallocene complex, a change in the coordination number of the transition metal, and the reduction of the transition metal can occur in these systems. A mechanism for the interaction of components in the indicated catalytic systems was proposed on the basis of our results obtained by various physicochemical methods and literature data.

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Reactivity of Metallocene Catalysts for Olefin Polymerization: Influence of Activator Nature and Structure

Cited by 158 publications

References 143 publications

Effect of Metallocene Structures on their Performance in Ethene Polymerisation

Effect of Metallocene Structures on their Performance in Ethene Polymerisation

Novel Organic Activators for Single Site Iron Catalysts

Mechanism of the interaction of components in the metallocene catalytic systems containing titanium and zirconium tetracyclopentadienyls and methylaluminoxane

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