Silanolytic Chain Transfer in Ziegler−Natta Catalysis. Organotitanium-Mediated Formation of New Silapolyolefins and Polyolefin Architectures

Koo, Kwangmo; Marks, Tobin J.

doi:10.1021/ja972194x

Cited by 76 publications

(43 citation statements)

References 14 publications

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“…In this instance, the styrene complex acts as a polymerization-limiting agent in the catalytic system (2) but preserves the cationic species from fast deactivation. In these terms recent data of Koo and Marks 44 on PhSiH 3 chain transfer in olefins and/or styrene copolymerization with catalyst (1) support the observations presented above. Thus, effective chain transfer with phenyl-containing silane was shown to proceed in the course of propylene, ethylene/hexene-1, and E/S polymerizations with catalyst (1).…”

Section: Catalytic System In Copolymerization Of E/ssupporting

confidence: 82%

Catalytic systems Me2SiCp*NtBuMX2/(CPh3)(B(C6F5)4) (M?Ti, X?CH3, M?Zr, X?iBu) in copolymerization of ethylene with styrene

Sukhova

Панин

Babkina

et al. 1999

J. Polym. Sci. A Polym. Chem.

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Catalytic activity of Me2SiCp*NtBuMX2/(CPh3)(B(C6F5)4) [MTi, XCH3 (1); MZr, X=iBu (2)] systems in the ethylene/styrene (E/S) feed was examined. Experimental data revealed high activity for the catalytic system (1) for copolymerization ethylene with styrene, whereas the system with enhanced catalytic activity for ethylene homopolymerization (2) was temporarily blocked in the styrene presence yielding, even at high styrene content, homopolyethylene as the final product. Properties of thus obtained polymers were analyzed. Catalytic system (1) occurred very sensitive to S/E ratio in the comonomers feed. The 10‐fold acceleration for ethylene consumption was shown in two experimental sets conducted at S/E = 1.3 ratio, 1 bar, and 7.5 bar ethylene pressure, respectively. The consequent enhancement in S/E ratio resulted in slowing down both ethylene consumption and catalyst deactivation rates. Atactic polystyrene was formed at high styrene content with the catalyst (1). Catalytic system (1) allowed design of products with the highest styrene content (20 mol %) at low ethylene pressure, moderate temperature, and high S/E ratio. The apparent activation energy estimated from the initial rates of ethylene consumption was 54.6 kJ/mol. Analysis of apparent reactivity factors (rE = 9 and rS = 0.04; rE × rS = 0.4) and 13C‐NMR copolymer spectra revealed an alternating tendency of the comonomers for active center incorporation. DSC measurements showed considerable decrease of melting points and crystallinity even for copolymers with low styrene content. The catalyst produced relatively high–molecular weight copolymers (140–150 kg/mol) even at 80°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1083–1093, 1999

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Section: Catalytic System In Copolymerization Of E/ssupporting

confidence: 82%

Catalytic systems Me2SiCp*NtBuMX2/(CPh3)(B(C6F5)4) (M?Ti, X?CH3, M?Zr, X?iBu) in copolymerization of ethylene with styrene

Sukhova

Панин

Babkina

et al. 1999

J. Polym. Sci. A Polym. Chem.

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“…45,46 Run 12 used triethylsilane in place of hexene/H 2 /D 2 . In accordance with previous results, 47 a significantly lower productivity rate was recorded than with either hexene, H 2 , or D 2 ; however, Et 3 Si was incorporated onto the end of some P(TBS) chains.…”

Section: Articlementioning

confidence: 99%

Zirconium-Catalyzed Polymerization of a Styrene: Catalyst Reactivation Mechanisms Using Alkenes and Dihydrogen

2011

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Zirconium salicylaldiminates in the presence of Al i Bu 3 /[Ph 3 C][B(C 6 F 5 ) 4 ] are inactive for the homopolymerization of p-tertbutylstyrene (TBS), but the addition of hexene leads to a highly active system. Analysis of the polymers by NMR and MALDI indicates surprisingly that most of the product chains contain no hexene, while some contain a single hexene unit. Addition of dihydrogen also leads to the production of poly(TBS) without substantial reduction in molecular weight and with main-chain endgroup unsaturation. These and other observations lead us to two related mechanisms for the hexene-and dihydrogen-promoted reactions. Synthetic and catalytic studies indicate that the active species is not a typical bis(salicylaldiminato) compound but an amido/alkoxido system. An authentic compound of this class is highly active for the TBS polymerization even in the absence of added aluminum alkyl.

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“…Siloxanes containing the SiH functional group are not useful for the polymerization of these monomers since the siloxane group is sufficiently nucleophilic to interact with the carbocationic intermediates in these polymerizations. It should be mentioned, however, that there is some evidence that alkyl and arylsilanes may function as chain transfer agents in the carbocationic polymerization of these monomers 31. At the same time, more highly reactive vinyl monomers such as vinyl ethers and N ‐vinylcarbazole as well as the ring‐opening polymerizations of heterocyclic monomers such as epoxides, oxetanes, and 1,3,5‐trioxane undergo facile cationic polymerization using redox couples based on N ‐aryl heteroaromatic onium salts and both simple silanes as well as SiH functional siloxanes.…”

Section: Resultsmentioning

confidence: 99%

Redox initiated cationic polymerization: Silane‐N‐aryl heteroaromatic onium salt redox couples

Crivello

Lee

2010

J. Polym. Sci. A Polym. Chem.

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In this article, a new route for the synthesis of N‐aryl heteroaromatic onium salts by the direct copper catalyzed arylation of pyridine, substituted pyridines, isoquinoline, and acridine with diaryliodonium salts is described. It was demonstrated that these N‐aryl heteroaromatic onium salts undergo facile platinum or rhodium‐catalyzed reduction by silanes bearing SiH groups. The reduction of N‐aryl heteroaromatic onium salts generates Brønsted acids. When this redox reaction was carried out in situ in the presence of an appropriate monomer, cationic polymerization was observed. Using this approach, the cationic polymerizations of epoxides, oxetanes, 1,3,5‐trioxane, styrene, and vinyl ethers were carried out. The use of optical pyrometry to monitor the redox initiated cationic polymerizations of some representative multifunctional monomers is described. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

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Silanolytic Chain Transfer in Ziegler−Natta Catalysis. Organotitanium-Mediated Formation of New Silapolyolefins and Polyolefin Architectures

Cited by 76 publications

References 14 publications

Catalytic systems Me2SiCp*NtBuMX2/(CPh3)(B(C6F5)4) (M?Ti, X?CH3, M?Zr, X?iBu) in copolymerization of ethylene with styrene

Catalytic systems Me2SiCp*NtBuMX2/(CPh3)(B(C6F5)4) (M?Ti, X?CH3, M?Zr, X?iBu) in copolymerization of ethylene with styrene

Zirconium-Catalyzed Polymerization of a Styrene: Catalyst Reactivation Mechanisms Using Alkenes and Dihydrogen

Redox initiated cationic polymerization: Silane‐N‐aryl heteroaromatic onium salt redox couples

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