End-capped Oligomers of Ethylene, Olefins and Dienes, by means of Coordinative Chain Transfer Polymerization using Rare Earth Catalysts

Chenal, Thomas; Visseaux, Marc

doi:10.5772/58217

Cited by 3 publications

(4 citation statements)

References 57 publications

(78 reference statements)

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“…During these studies, we found that the rate of CCTP of ethylene in toluene at 40 °C dramatically decreases after the formation of Mg(PE) 2 species with P n ∼ 16–20 . Additionally, it has been established experimentally that higher molecular masses of Mg(PE) 2 ( P n ∼ 70–150, SEC data) can be achieved for complexes I and II (Scheme ) at ∼80 °C; − however, at increased temperatures, the reaction is complicated by β-hydride elimination with the formation of terminal vinyl groups. ,, …”

Section: Resultsmentioning

confidence: 97%

“…14 Additionally, it has been established experimentally that higher molecular masses of Mg(PE) 2 (P n ∼ 70−150, SEC data) can be achieved for complexes I and II (Scheme 1) at ∼80 °C; 10−12 however, at increased temperatures, the reaction is complicated by βhydride elimination with the formation of terminal vinyl groups. 7,14,25 The scheme for Ln/Mg chain transfer polymerization previously proposed by Boisson et al 15 involved the formation of trinuclear (LnMg 2 ) complexes with bridging alkyl fragments; polymer chain growth includes the dissociation of this complex, coordination and insertion of an ethylene molecule, and the subsequent recombination of L−Ln−alkyl and Mg 2 (alkyl) 4 (Scheme 3A). Fast polymer chain transfer via dissociation− recombination of the LnMg 2 species ensures the near equal growth of all f ive alkyl fragments bound to the metal atoms of a trinuclear catalytic complex, which is confirmed by the narrow molecular weight distribution (MWD) of α-functionalized PE derivatives formed.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Aryloxy Alkyl Magnesium versus Dialkyl Magnesium in the Lanthanidocene-Catalyzed Coordinative Chain Transfer Polymerization of Ethylene

et al. 2019

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Complexes [(1,2,4-Ph3C5H2)2NdCl2K(THF)2]2 (Nd1), {[1,2-Ph2-4-(4-MeOC6H4)C5H2]2NdCl2K(THF)2}2 (Nd2), {[1,2-Ph2-4-(2-MeOC6H4)C5H2]2NdCl2[K(THF)4]}(THF)0.5 (Nd3), and [(1,2,4-Ph3C5H2)2TbCl2K]2 (Tb1) have been synthesized, studied by X-ray diffraction analysis, and used in coordinative chain transfer polymerization (CCTP) of ethylene upon activation by alkyl magnesium derivatives. The complexes Nd1 and Tb1 exhibiting similar molecular structures and the same core type have demonstrated similar catalytic activities. Two types of alkylating/chain transfer agents, namely, di-n-butyl magnesium and heteroleptic complex (BHT)Mg(THF)2 n Bu Mg1 (BHT = 2,6-di-tert-butyl-4-methylphenoxide), have been studied in this reaction. We have found that (BHT)Mg(PE) products (PE is an oligoethylene chain) are being formed at a relatively high rate while using Mg1 at 40 °C in the solution polymerization of ethylene; the oligomeric products comprise more than 40 ethylene fragments, unlike Mg(PE)2 derivatives, which are obtained from Mg n Bu2 and contain about 20 ethylene fragments. Luminescence spectroscopy study of the reaction mixtures, while initiating the complex Tb1 by Mg n Bu2 or Mg1, confirmed the structural proximity and high symmetry of the catalytic complexes for both types of Mg reagents. These experimental results reaffirmed the hypothesis about the CCTP mechanism, suggesting the formation of trinuclear LnMg2 catalytic species. Within this mechanism, we can explain the increase in the polymerization degree (P n ) when Mg1 is used by growing a single oligoethylene chain (PE) per a Mg atom to form (μ-BHT)2Mg2(PE)2 species, whereas application of Mg n Bu2 provides the growth of two PE chains to form the Mg2(PE)4 product with lower solubility.

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Section: Resultsmentioning

confidence: 97%

Section: ■ Results and Discussionmentioning

confidence: 99%

Aryloxy Alkyl Magnesium versus Dialkyl Magnesium in the Lanthanidocene-Catalyzed Coordinative Chain Transfer Polymerization of Ethylene

et al. 2019

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“…The CTA binds to the active catalyst by blocking the site for monomer coordination in a rapidly maintained equilibrium forming heterobimetallic complexes, [6] which are responsible for the chain transfer. Thus, the chain propagation rate or polymerization activity depends on the CTA concentration in an inverse first‐order [13a 7] . This inverse first‐order dependence has restricted CCTP to very low CTA‐to‐catalyst ratios equate with a low number of polymer chains a catalyst molecule can grow in a controlled fashion (Figure 1C).…”

Section: Figurementioning

confidence: 99%

“…Thus, the chain propagation rate or polymerization activity depends on the CTA concentration in an inverse first‐order. [ 7 , 13a ] This inverse first‐order dependence has restricted CCTP to very low CTA‐to‐catalyst ratios equate with a low number of polymer chains a catalyst molecule can grow in a controlled fashion (Figure 1C ). Key catalyst development for reversible CCTP has been described by the groups of Mortreux, [8] Gibson and Britovsek, [9] us, [10] Sita and co‐worker.…”

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confidence: 99%

The Highly Controlled and Efficient Polymerization of Ethylene

et al. 2023

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The highly controlled and efficient polymerization of ethylene is a very attractive but challenging target. Herein we report on a Coordinative Chain Transfer Polymerization catalyst, which combines a high degree of control and very high activity in ethylene oligo-or polymerization with extremely high chain transfer agent (triethylaluminum) to catalyst ratios (catalyst economy). Our Zr catalyst is long living and temperature stable. The chain length of the polyethylene products increases over time under constant ethylene feed or until a certain volume of ethylene is completely consumed to reach the expected molecular weight. Very high activities are observed if the catalyst elongates 60 000 or more alkyl chains and the polydispersity of the strictly linear polyethylene materials obtained are very low. The key for the combination of high control and efficiency seems to be a catalyst stabilized by only one strongly bound monoanionic N-ligand.

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Catalyzed chain growth polymerisation of ethylene using lanthanidocenes/dialkylmagnesium: further developments and one pot synthesis of narrow dispersed high molecular weight fatty alcohols

Chenal

Drelon

Marsh

et al. 2020

Catal. Sci. Technol.

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End-capped Oligomers of Ethylene, Olefins and Dienes, by means of Coordinative Chain Transfer Polymerization using Rare Earth Catalysts

Cited by 3 publications

References 57 publications

Aryloxy Alkyl Magnesium versus Dialkyl Magnesium in the Lanthanidocene-Catalyzed Coordinative Chain Transfer Polymerization of Ethylene

Aryloxy Alkyl Magnesium versus Dialkyl Magnesium in the Lanthanidocene-Catalyzed Coordinative Chain Transfer Polymerization of Ethylene

The Highly Controlled and Efficient Polymerization of Ethylene

Catalyzed chain growth polymerisation of ethylene using lanthanidocenes/dialkylmagnesium: further developments and one pot synthesis of narrow dispersed high molecular weight fatty alcohols

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