The Influence of Aromatic Substituents on the Polymerization Behavior of Bridged Zirconocene Catalysts

Spaleck, Walter; Kueber, F.; Winter, Andreas; Rohrmann, Juergen; Bachmann, Bernd; Antberg, M.; Dolle, Volker; Paulus, E. F.

doi:10.1021/om00015a032

Cited by 564 publications

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“…5 They have also applied Si(CH 3 ) 2 (Ind) 2 ZrCl 2 to the isotactic polymerization of polypropylene. 7 We chose the former metallocene as a parent catalyst for studying the stereochemistry behavior during the first and second insertion. The active catalyst for the present investigation is SiH 2 (Ind) 2 ¹ as CA.…”

Section: Resultsmentioning

confidence: 99%

“…5 This concept has been best exemplified in the [Me 2 Si(Ind) 2 ]ZrCl 2 (Ind = indenyl) and [Me 2 C(Flu)(Cp)]ZrCl 2 (Cp = C 5 H 5 , Flu = fluorenyl) singlesite catalysts. The former affords isotactic polymers, 6,7 whereas the latter produces syndiotactic polymers 8 from propylene. Brintzinger et al synthesized a large number of ansa metallocenes, in which C 2 symmetric metallocenes produce isotactic polymers and C s symmetric metallocenes yield syndiotactic polymers.…”

Section: Introductionmentioning

confidence: 99%

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Revisiting the Stereochemistry of Propylene Isotactic Polymerization Reaction Mechanism on C2 Symmetric [SiH2(Ind)2ZrCH3]+ and [SiH2(Ind)2ZrCH3]+[CH3B(C6F5)3]−

Sandhya¹,

Koga²,

Nagaoka³

2016

Bulletin of the Chemical Society of Japan

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The [SiH 2 (Ind) 2 ZrCH 3 ] + (Ind = indenyl) catalyzed stereoregularity of propylene polymerization mechanism has been investigated at M06 level of theory. Four different approaches of propylene to the reactive catalyst lead to four isomeric products due to the C 2 symmetry of bridged Ind ligand of the catalyst. Consequently, various possibilities of propylene attack as well as orientation of polymer chain yield numerous stereoisomers. The calculations of the first and second insertions with various conformers clarified the most favorable reaction pathway and showed that isotactic propagation is more favorable (3.5 kcal mol ¹1 ) than syndiotactic propagation. The structures of resting state catalysts displayed various agostic interactions of the CH bond with the Zr center which stabilize the catalytic systems and play important roles in determining the favorable reaction pathway. The influence of counter anion¹ on the reactivity of the catalyst was also studied. The results also confirm that the trans orientation of the counter anion with respect to propylene is more favorable than its cis orientation and clarify the most favorable reaction pathway in the first and second insertion. Because agostic interactions are involved in various aspects, AIM analysis has been used to find the bonding nature of agostic interactions as well as ion-pair bonds. The overall results suggest that rigidity of ansa-zirconocene, unique structure of C 2 symmetric ansa ligand, influence of [CH 3 B(C 6 F 5 ) 3 ]¹ and β agostic interaction may restrict the attack of propylene only to isotactic polymerization and not to syndiotactic polymerization.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Revisiting the Stereochemistry of Propylene Isotactic Polymerization Reaction Mechanism on C2 Symmetric [SiH2(Ind)2ZrCH3]+ and [SiH2(Ind)2ZrCH3]+[CH3B(C6F5)3]−

Sandhya¹,

Koga²,

Nagaoka³

2016

Bulletin of the Chemical Society of Japan

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“…The experiments were designed for producing the copolymer with the high incorporation of 4P1O. Although the catalyst, racMe 2 Si(2-Me-4-Ph-Ind) 2 ZrCl 2 , exhibited high activity and offered the polymer with the high molecular weight in propylene polymerization [33], the activity for the copolymerization of 4M1P was pretty low, and the molecular weight of the resulted polymer was also low. The 13 C-NMR spectrum of the copolymer of 4M1P with 4P1O (sample 9) was given in Figure 3, in comparison to that of sample 1.…”

Section: Thementioning

confidence: 99%

Copolymerization of 4-methyl-1-pentene with α,ω-alkenols

Wang¹,

Hou²,

Sheng³

et al. 2016

Express Polym. Lett.

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Abstract. Copolymerization of 4-methyl-1-pentene (4M1P) with 9-decen-1-ol (9D1O) or 4-penten-1-ol (4P1O) was conducted by using metallocene catalysts. The activity could be improved under the higher polymerization temperature. The dyad distribution of poly(4M1P-co-4P1O) was presented. The results showed that 4P1O was uniformly distributed in the copolymer chain. The melting temperature (T m ) of the copolymer was lower than that of poly(4M1P), and was decreased with the increase of the incorporation of comonomer. T m of poly(4M1P-co-4P1O) was determined as 185°C, even the incorporation of 4P1O was high as 15.0 mol%. WAXD (wide-angle X-ray diffraction) results showed that the poly(4M1P) was observed as crystalline form II, and turned to form I when the incorporation of α,ω-alkenols were high. Some new peaks, which were never observed in the previous researches, appeared in the X-ray diffraction profiles for poly(4M1P-co-4P1O). It is inferred that the similar chain length of 4P1O and 4M1P may be the key factor.

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“…The commercial production of iPP has mainly focused on the increase in molecular weight (M w ) and isotacticity of polypropylene, as well as the increase in catalytic activity by the change of catalyst structure. [3][4][5][6] Although many elaborated catalyst structures suitable for commercial iPP have been reported, [7][8][9][10][11][12][13][14] the synthetic procedures towards such C 2 -symmetric catalysts usually require many difficult steps giving rise to the increase in catalyst costs during the course of commercialization of iPP products. The high cost has been one of the principal reasons why the portion of metallocene-iPP products is below 1% of the total iPP market.…”

Section: Introductionmentioning

confidence: 99%

Isospecific Propylene Polymerization Behavior of Lewis Base Functionalized Unbridged Zirconocences under Bulk Conditions

Yoon¹,

Kim²,

Kim³

et al. 2014

Bulletin of the Korean Chemical Society

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Isospecific propylene polymerization behavior of meta-and para-Lewis base (E) functionalized unbridged zirconocenes ([1-(E n -Ph)-3,4-Me 2 C 5 H 2 ] 2 ZrCl 2 , E = NMe 2 , OMe; n = 1 or 2) was investigated under bulk conditions. Catalytic activity of the zirconocenes, and molecular weight and isotacticity of polypropylenes are found to be dependent on the position and number of the Lewis base functional groups in the zirconocenes. All the crude polypropylenes possess a broad molecular weight distribution and multi-melting transitions, indicating an involvement of multi-catalytic active species in the polymerization. The highest [mmmm] value of an isotactic portion of the polypropylenes reached 89%, which is higher than that (85%) from the wellknown C 2 -symmetric EBIZr (rac-Et(Ind) 2 ZrCl 2 ) catalyst. These results support that the in situ generated, rigid rac-like cation-anion pair through the Lewis acid-base interactions between the functional groups of zirconocenes and methylaluminoxane anion is effective in the formation of isotactic polypropylene under bulk propylene polymerization conditions.

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The Influence of Aromatic Substituents on the Polymerization Behavior of Bridged Zirconocene Catalysts

Cited by 564 publications

References 0 publications

Revisiting the Stereochemistry of Propylene Isotactic Polymerization Reaction Mechanism on C2 Symmetric [SiH2(Ind)2ZrCH3]+ and [SiH2(Ind)2ZrCH3]+[CH3B(C6F5)3]−

Revisiting the Stereochemistry of Propylene Isotactic Polymerization Reaction Mechanism on C2 Symmetric [SiH2(Ind)2ZrCH3]+ and [SiH2(Ind)2ZrCH3]+[CH3B(C6F5)3]−

Copolymerization of 4-methyl-1-pentene with α,ω-alkenols

Isospecific Propylene Polymerization Behavior of Lewis Base Functionalized Unbridged Zirconocences under Bulk Conditions

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