Mechanistic Studies of Catalytic Polyethylene Chain Growth in the Presence of Water

Berkefeld, Andreas; Mecking, Stefan

doi:10.1002/anie.200601387

Cited by 30 publications

(17 citation statements)

References 29 publications

(16 reference statements)

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“…A highly linear semicrystalline polyethylene was obtained, with, for example, a molecular weight of M n ) 1.4 × 10 5 g mol -1 (M w / M n ) 2.1, 50% crystallinity; prepared at 30 bar). In polymerization experiments of variable duration (5,20,30, and 60 min), the polymer yield increased linearly with time. This indicates a high stability of the active species under these conditions.…”

Section: Resultsmentioning

confidence: 91%

Deactivation Pathways of Neutral Ni(II) Polymerization Catalysts

Berkefeld

Mecking

2009

J. Am. Chem. Soc.

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The novel dimethyl sulfoxide (DMSO)-coordinated complex [(N,O)Ni(CH(3))(DMSO)] {1-DMSO; (N,O) = kappa(2)-N,O-(2,6-(3,5-(F(3)C)(2)C(6)H(3))(2)C(6)H(3))-N=CH-(3,5-I(2)-2-OC(6)H(2))} was found to be a well-defined, very reactive precursor that enables direct observation of the activation and deactivation of neutral Ni(II) catalysts. Preparative reaction with ethylene afforded the ethyl complex [(N,O)Ni((alpha)CH(2)(beta)CH(3))(DMSO)] (2-DMSO). 2-DMSO is subject to interconversion of the (alpha)C and (beta)C moieties via an intermediate [(N,O)Ni(II)H(ethylene)] complex (this process is slow on the NMR time scale). Exposure of 1-DMSO to ethylene in DMSO solution at 55 degrees C results in partial reaction to form propylene (pseudo-first-order rate constant k(ins,Me) = 6.8 +/- 0.3 x 10(-4) s(-1) at an ethylene concentration of 0.15 M) and conversion to 2-DMSO, which catalyzes the conversion of ethylene to butenes. A relevant decomposition route of the catalyst precursor is the bimolecular elimination of ethane [DeltaH(double dagger) = (57 +/- 1) kJ mol(-1) and DeltaS(double dagger) = -(129 +/- 2) J mol(-1) K(-1) over the temperature range 55-80 degrees C]. This reaction is specific to the Ni(II)-Me complex; corresponding homocoupling of the higher Ni(II)-alkyls of the propagating species in catalytic C-C linkage of ethylene was not observed, but Ni(II)-Me reacted with Ni(II)-Et to form propane, as concluded from studies with 2-DMSO and its analogue that is perdeuterated in the Ni(II)-Et moiety. Under the reaction conditions of the aforementioned catalytic C-C linkage of ethylene, additional ethane evolves from the reaction of intermediate Ni(II)-Et with Ni(II)-H. This is independently supported by reaction of 2-DMSO with the separately prepared hydride complex [(N,O)NiH(PMe(3))] (3-PMe(3)) to afford ethane. Kinetic studies show this reaction to be bimolecular [DeltaH(double dagger) = (47 +/- 6) kJ mol(-1) and DeltaS(double dagger) = -(117 +/- 15) J mol(-1) K(-1) over the temperature range 6-35 degrees C]. In contrast to these reactions identified as decomposition routes, hydrolysis of Ni(II)-alkyls by added water (D(2)O; H(2)O) occurred only to a minor extent for the Ni(II)-Me catalyst precursor, and no clear evidence of hydrolysis was observed for higher Ni(II)-alkyls. The rate of the aforementioned insertion of ethylene in 1-DMSO and the rate of catalytic ethylene dimerization are not affected by the presence of water, indicating that water also does not compete significantly with the substrate for binding sites.

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Section: Resultsmentioning

confidence: 91%

Deactivation Pathways of Neutral Ni(II) Polymerization Catalysts

Berkefeld

Mecking

2009

J. Am. Chem. Soc.

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“…In 2006, Mecking and co-workers reported on the synthesis of the processable polyacetylene nanoparticles by the polymerization of acetylene in an aqueous miniemulsion method. 7 For this purpose, a Pd catalyst was dissolved in a minimum amount of a mixture of hexane-ethanol, and added into an aqueous solution of surfactant and organic acid (sodium dodecylsulfate and methane sulfonic acid). Subsequently, this mixture was sonicated to form a miniemulsion.…”

Section: Miniemulsionmentioning

confidence: 99%

Conjugated polymer nanoparticles

2010

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Conjugated polymer nanoparticles are highly versatile nano-structured materials that can potentially find applications in various areas such as optoelectronics, photonics, bio-imaging, bio-sensing and nanomedicine. Their straightforward synthesis in desired sizes and properties, biocompatibility and non-toxicity make these materials highly attractive for the aforementioned applications. This feature article reviews the recent developments in the synthesis, characterization, properties and application of these exciting nanostructured materials.

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“…Diimine Pd and salicylaldimine Ni complexes are stable toward hydrolysis and water does not interfere the coordination and insertion of ethylene to metal-carbon bond (Scheme 4.12) [245,246]. Coordination of ethylene molecule to cationic diimine Pd aqua complex and subsequent insertion to its Pdcarbon bonds are directly observed by NMR.…”

Section: Olefin Polymerization In Aqueous Mediamentioning

confidence: 92%

Olefin Polymerization with Non-metallocene Catalysts (Late Transition Metals)

Takeuchi

2014

Organometallic Reactions and Polymerization

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Diimine Pd and Ni complexes catalyze the polymerization of ethylene, propylene, and a-olefins. The reaction involves isomerization of the growing terminal (chain walking) and, as its result, produces highly branched polyethylene and poy(a-olefin)s having a smaller number of the alkyl substituents than expected from the monomer structure. Ni complexes with salicylaldimine or iminocarboxamide ligands and Pd complexes with phosphinesulfonate ligands are used as single component catalysts for ethylene polymerization. Especially, the latter catalysts show tolerance towards polar functional groups and promote copolymerization of ethylene with wide varieties of polar monomers. The Pd and Ni complexes are able to catalyze ethylene polymerization in aqueous media to yield polyethylene particles. Fe and Co complexes with bis(imino)pyridine ligands show high catalytic activity for ethylene polymerization to yield linear polyethylene. Complexes of the metals such as Rh, Ir, Ru, and Ag were revealed to become catalytically active by proper design of the ligand. Not only monometallic complexes but also bimetallic or multimetallic complexes are used for ethylene polymerization. Late transition metal complexes catalyze selective cyclopolymerization of non-conjugated dienes and trienes to afford the polymers with cycloalkane groups with controlled stereochemistry.

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Mechanistic Studies of Catalytic Polyethylene Chain Growth in the Presence of Water

Cited by 30 publications

References 29 publications

Deactivation Pathways of Neutral Ni(II) Polymerization Catalysts

Deactivation Pathways of Neutral Ni(II) Polymerization Catalysts

Conjugated polymer nanoparticles

Olefin Polymerization with Non-metallocene Catalysts (Late Transition Metals)

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