Synthesis and Reactivity of Ester‐Functionalized 5‐Membered Rh<sup>I</sup>‐κ<sup>2</sup>‐C,O‐Chelates and Their Relevance in Rh(cod)‐Mediated Carbene Polymerization

Finger, Markus; Lutz, Martin; Reek, Joost N. H.; Bruin, Bas de

doi:10.1002/ejic.201100981

Cited by 12 publications

(14 citation statements)

References 49 publications

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“…1,5-cyclooctadiene (cod) derivatives) under the applied reaction conditions. 267,277,279 These findings are expected to lead to future improvements of this approach in terms of yields, initiation efficiencies of the catalysts and in the synthesis of stereoregular polymers with different tacticities. This clearly indicates that this new reaction has not yet been exploited at its full potential.…”

Section: Scheme 49 Migratory Insertion Of Carbenesmentioning

confidence: 92%

“…266 The reaction proceeds via a migratory insertion mechanism (Scheme 55) 266 and no or little chain transfer seems to occur. [275][276][277][278] Most recently, detailed mechanistic studies revealed that the active species responsible for this polymerisation is a Rh III (allyl)(alkyl) species (Fig. 7) that can be formed by modifications of rather simple Rh I (diene) precursors (e.g.…”

Section: Scheme 49 Migratory Insertion Of Carbenesmentioning

confidence: 99%

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Synthesis of functional ‘polyolefins’: state of the art and remaining challenges

2013

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Functional polyolefins (i.e., polyethene or polypropene bearing functional groups) are highly desired materials, due to their beneficial surface properties. Many different pathways exist for the synthesis of these materials, each with its own advantages and drawbacks. This review focuses on those synthetic pathways that build up a polymer chain from ethene/propene and functionalised polar vinyl monomers. Despite many recent advances in the various fields of olefin polymerisation, it still remains a challenge to synthesise high molecular-weight copolymers with tuneable amounts of functional groups, preferably with consecutive insertions of polar monomers occurring in a stereoselective way. To overcome some of these challenges, polymerisation of alternative functionalised monomers is explored as well.

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Section: Scheme 49 Migratory Insertion Of Carbenesmentioning

confidence: 92%

Section: Scheme 49 Migratory Insertion Of Carbenesmentioning

confidence: 99%

Synthesis of functional ‘polyolefins’: state of the art and remaining challenges

2013

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“…This is in agreement with previously-described chain transfer/ termination pathways. 50,58 The polymer yield drops upon incorporation of ethene as compared to the yields obtained in the carbene homopolymerisation reactions. Previous studies on the EDA homopolymerisation revealed that chain transfer occurs only to a very limited extent.…”

Section: Olefin-carbene Copolymerizationsmentioning

confidence: 99%

“…[29][30][31][32][33][34][35][36][37][38][39][40][41][42] Highly stereospecific (co)polymerisation of diazoesters (N 2 CHCOOR) can be achieved in good yields and with high M w in a Rh catalysed process. 30,[43][44][45][46][47][48][49][50][51] This leads to the formation of syndiotactic polymers bearing an ester functionality at every single carbon atom of the polymer main chain.…”

Section: Introductionmentioning

confidence: 99%

A different route to functional polyolefins: olefin–carbene copolymerisation

2013

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Copolymerisation of carbenes and olefins (ethene), mediated by Rh-based catalyst precursors, is presented as a new, proof-of-concept methodology for the controlled synthesis of functional polymers. The reactions studied show that olefin-carbene polymerisation reactions provide a viable alternative to more traditional olefin polymerization techniques. Rh(III)-catalyst precursors, while active in the homopolymerisation of either olefins or carbenes, proved to be virtually inactive in olefin-carbene copolymerization. Conversely, the use of Rh(I)(cod) catalyst precursors allows the synthesis of high molecular-weight, highly functionalized copolymers. The reactions yield a mixture of copolymers and some carbene homopolymers, which proved to be difficult to separate. Polyethylene was not formed under the applied reaction conditions. The average ethene content in this mixture could be increased up to 11%, although analysis of the mixture revealed that the ethene content in fractions of the copolymer mixture can be as high as 70%. Attempts to increase the ethene content by increasing the ethene pressure unexpectedly led to lower average ethene contents, which is most likely due to changes in the ratio of copolymers vs. carbene homopolymer. This behaviour is most likely a result of the reactivity difference of different active Rh-species formed under the applied reaction conditions. Apparently, higher ethene concentrations slow down the copolymerisation process (mediated by yet unidentified Rh-species) compared to the formation of homopolymers (mediated by different Rh-catalysts; most likely (allyl)Rh(III)-alkyl species), thereby changing the product ratio in favour of the homopolymer. The average ethene content in the copolymer mixture therefore decreases, while the ethene content within the copolymer fraction has likely increased at higher ethene concentrations (but simply less copolymer is formed). The obtained copolymers exhibit a blocky microstructure, with the functional blocks being highly stereoregular. Branching does occur and the functional groups are present in the polymer backbone as well as at the branches. Formation of copolymers was confirmed by Maldi-ToF analysis, which revealed incorporation of several ethene units into the copolymers.

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“…Recently, we have shown that highly stereospecific polymerization of polar monomers can be achieved in good yields and with high M w by Rh-catalyzed (co)polymerization of diazoesters (N 2 CHCOOR). ,− This leads to the formation of syndiotactic polymers bearing an ester functionality at every single carbon atom of the polymer main chain via a coordination/insertion mechanism (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

Controlled Synthesis of Functional Copolymers with Blocky Architectures via Carbene Polymerization

et al. 2012

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We present our results obtained in the Rh-catalyzed carbene copolymerization of diazomethane and diazoesters as a new approach to functional polymer synthesis. Copolymerization reactions were successful, and high-M w ethylene–acrylate type copolymers were obtained with a large variation in functional group content, which proved to be tunable by varying the monomer feed ratio and the way of addition. Polymer yields decrease strongly with increasing incorporation of diazomethane due to rapid β-hydride elimination. Sequential insertions of polar monomers were observed to a large extent, giving rise to copolymers with a blocky microstructure, which is a unique feature of this polymerization technique. The copolymer properties are demonstrated to be highly dependent on the functional group content and can therefore easily be varied in the window between the properties of both homopolymers.

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Synthesis and Reactivity of Ester‐Functionalized 5‐Membered Rh^I‐κ²‐C,O‐Chelates and Their Relevance in Rh(cod)‐Mediated Carbene Polymerization

Cited by 12 publications

References 49 publications

Synthesis of functional ‘polyolefins’: state of the art and remaining challenges

Synthesis of functional ‘polyolefins’: state of the art and remaining challenges

A different route to functional polyolefins: olefin–carbene copolymerisation

Controlled Synthesis of Functional Copolymers with Blocky Architectures via Carbene Polymerization

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Synthesis and Reactivity of Ester‐Functionalized 5‐Membered RhI‐κ2‐C,O‐Chelates and Their Relevance in Rh(cod)‐Mediated Carbene Polymerization

Cited by 12 publications

References 49 publications

Synthesis of functional ‘polyolefins’: state of the art and remaining challenges

Synthesis of functional ‘polyolefins’: state of the art and remaining challenges

A different route to functional polyolefins: olefin–carbene copolymerisation

Controlled Synthesis of Functional Copolymers with Blocky Architectures via Carbene Polymerization

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Synthesis and Reactivity of Ester‐Functionalized 5‐Membered Rh^I‐κ²‐C,O‐Chelates and Their Relevance in Rh(cod)‐Mediated Carbene Polymerization