The Interplay of ATRP, OMRP and CCT in Iron-Mediated Controlled Radical Polymerization

Lake, Benjamin R. M.; Shaver, Michael P.

doi:10.1021/bk-2015-1187.ch017

Cited by 9 publications

(7 citation statements)

References 48 publications

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“…In addition to atom transfer reactions, iron catalysts (L/Fe II ) can also react with the propagating radicals to form organometallic species (P n -L/Fe III ). While the organometallic species can be involved in an organometallic mediated radical polymerization (OMRP) mechanism [29,30], termination reactions may also be promoted through catalytic chain transfer (CCT) [31] or catalytic radical termination (CRT) processes involving P n -L/Fe III species and propagating radicals to yield terminated chains [32]. In copper-catalyzed ATRP, CRT was reported only for the most active catalysts.…”

Section: Introductionmentioning

confidence: 99%

Iron Catalysts in Atom Transfer Radical Polymerization

Dadashi‐Silab

Matyjaszewski

2020

Molecules

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Catalysts are essential for mediating a controlled polymerization in atom transfer radical polymerization (ATRP). Copper-based catalysts are widely explored in ATRP and are highly efficient, leading to well-controlled polymerization of a variety of functional monomers. In addition to copper, iron-based complexes offer new opportunities in ATRP catalysis to develop environmentally friendly, less toxic, inexpensive, and abundant catalytic systems. Despite the high efficiency of iron catalysts in controlling polymerization of various monomers including methacrylates and styrene, ATRP of acrylate-based monomers by iron catalysts still remains a challenge. In this paper, we review the fundamentals and recent advances of iron-catalyzed ATRP focusing on development of ligands, catalyst design, and techniques used for iron catalysis in ATRP.

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Section: Introductionmentioning

confidence: 99%

Iron Catalysts in Atom Transfer Radical Polymerization

Dadashi‐Silab

Matyjaszewski

2020

Molecules

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“…The first examples of Fe-mediated R-ATRP were reported by Teyssié et al, 16 whereas amine bisphenolate complexes of both Fe II and Fe III showed good control in the RP of styrene and methyl methacrylate (MMA), 17−21 through joint ATRP and organometallic-mediated radical polymerization mechanisms. 22,23…”

Section: Introductionmentioning

confidence: 99%

“…These systems traditionally feature an azo initiator (such as AIBN) and proceed via a reverse ATRP (R-ATRP) mechanism (Scheme ). The first examples of Fe-mediated R-ATRP were reported by Teyssié et al, whereas amine bisphenolate complexes of both Fe II and Fe III showed good control in the RP of styrene and methyl methacrylate (MMA), − through joint ATRP and organometallic-mediated radical polymerization mechanisms. , …”

Section: Introductionmentioning

confidence: 99%

Iron^III Half Salen Catalysts for Atom Transfer Radical and Ring-Opening Polymerizations

et al. 2018

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A series of monometallic pentacoordinate Fe III chloride complexes have been prepared and characterized by high-resolution mass spectrometry and elemental analysis. X-ray diffraction analysis showed that the bis-chelated Fe III complexes bear distorted trigonal bipyramidal geometries. The air- and moisture-stable Fe III complexes were screened as mediators in the reverse atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate. Moderate to excellent control was achieved with dispersities as low as 1.1 for both poly(methyl methacrylate) and polystyrene. Kinetic studies showed living characteristics, and end group analysis revealed the presence of olefin-terminated polymer chains, suggesting catalytic chain transfer as a competing polymerization mechanism. Although the catalysts are not the fastest Fe ATRP mediators, they are robust and flexible. Using propylene oxide as an initiator, the complexes were active catalysts for the ring-opening polymerization of rac -lactide with moderate control. While the addition of propylene oxide has been reported as an efficient method of converting a metal–halide bond to a metal–alkoxide bond in situ, we show herein that this initiation mechanism can limit polymerization reproducibility and introduce an induction period.

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“…The possibility of concurrent atom transfer and radical transfer has recently been realised for some of the most active Cu-based ATRP systems [68][69][70][71] and is invoked in order to explain unusual experimental phenomena. 72 However, the organometallic complex has never been directly observed in these systems.…”

Section: Ley-griffith Oxidationmentioning

confidence: 99%

“…OMRP has been successfully conducted using a variety of transition metals including vanadium, [189][190] chromium, 191 molybdenum 5 and iron. 69,[192][193] The pioneering work of Wayland et al 64 utilised a tetramesitylporphyrinato complex of cobalt as the capping agent and cobalt remains the most popular transition metal for effecting these transformations. [65][66][194][195][196][197] Acetylacetonate and dioxime chelating ligands are useful aternatives to porphyrins (Figure 4-1).…”

Section: Introductionmentioning

confidence: 99%

Understanding the mechanisms of transition metal catalysed redox reactions

Zerk¹

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Transition metal complexes catalyse a number of important synthetic chemical reactions. Two such reactions which rely on copper and ruthenium complexes respectively are atom transfer radical polymerisation (ATRP) and the Ley-Griffith oxidation of alcohols.In ATRP a copper(I) complex bearing a chelate ligand 'L' homolytically cleaves the carbon-halogen bond of an organo halide initiator (R-X) to produce an alkyl radical and the corresponding copper(II)-halido complex (Cu I L + RX → R• + Cu II LX). The reverse reaction is coined 'deactivation' and provides control to the process by keeping the concentration of the radical low. It is experimentally difficult to determine the rate of this reaction because it is so fast. Herein, a new method for measuring the rate of deactivation is developed using cyclic voltammetry coupled to simulations. The mechanism of deactivation is also unknown and this aspect is investigated by a kinetic study of halide substitution reactions on three ATRP-relevant Cu ). EPR spectroscopy alsoshows that NMO forms an outer-sphere associated complex with perruthenate which may be important in facilitating this reaction. Finally, synergistic EPR and UV-vis spectroscopy demonstrate that even with a large excess of NMO, a small amount of ruthenium dioxide still forms during the Ley-Griffith oxidation and acts as an accelerant for the reaction -i.e. the reaction is auto-catalytic. Declaration by author

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The Interplay of ATRP, OMRP and CCT in Iron-Mediated Controlled Radical Polymerization

Cited by 9 publications

References 48 publications

Iron Catalysts in Atom Transfer Radical Polymerization

Iron Catalysts in Atom Transfer Radical Polymerization

Iron^III Half Salen Catalysts for Atom Transfer Radical and Ring-Opening Polymerizations

Understanding the mechanisms of transition metal catalysed redox reactions

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The Interplay of ATRP, OMRP and CCT in Iron-Mediated Controlled Radical Polymerization

Cited by 9 publications

References 48 publications

Iron Catalysts in Atom Transfer Radical Polymerization

Iron Catalysts in Atom Transfer Radical Polymerization

IronIII Half Salen Catalysts for Atom Transfer Radical and Ring-Opening Polymerizations

Understanding the mechanisms of transition metal catalysed redox reactions

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Iron^III Half Salen Catalysts for Atom Transfer Radical and Ring-Opening Polymerizations