Sustainable Concepts in Olefin Metathesis

Clavier, Hervé; Grela, Karol; Kirschning, Andreas; Mauduit, Marc; Nolan, Steven P.

doi:10.1002/anie.200605099

Cited by 340 publications

(144 citation statements)

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“…Numerous methods to reduce the level of ruthenium in metathesis products have been developed. Heterogeneous methods, such as supported metathesis catalysts, have been reviewed extensively [18][19][20] . However, supported catalysts have a few drawbacks, some of which are high catalyst loadings, low turnover numbers and tedious synthetic procedures.…”

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confidence: 99%

Catalytic living ring-opening metathesis polymerization

Nagarkar

Kilbinger

2015

Nature Chem

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In living ring-opening metathesis polymerization (ROMP), a transition-metal-carbene complex polymerizes ring-strained olefins with very good control of the molecular weight of the resulting polymers. Because one molecule of the initiator is required for each polymer chain, however, this type of polymerization is expensive for widespread use. We have now designed a chain-transfer agent (CTA) capable of reducing the required amount of metal complex while still maintaining full control over the living polymerization process. This new method introduces a degenerative transfer process to ROMP. We demonstrate that substituted cyclohexene rings are good CTAs, and thereby preserve the 'living' character of the polymerization using catalytic quantities of the metal complex. The resulting polymers show characteristics of a living polymerization, namely narrow molecular-weight distribution, controlled molecular weights and block copolymer formation. This new technique provides access to well-defined polymers for industrial, biomedical and academic use at a fraction of the current costs and significantly reduced levels of residual ruthenium catalyst. In olefin metathesis reactions, olefinic bonds are rearranged with the help of a transition-metal catalyst 1,2 . In the early days following the discovery of this reaction, ill-defined catalysts 3 were used to carry out this transformation. After Herisson and Chauvin 4 had proposed a reaction mechanism, the olefin metathesis reaction was better understood and soon gained much popularity. Typical catalysts used for olefin metathesis reactions include those based on ruthenium (developed mainly by the Grubbs group 5 ), tungsten and molybdenum (developed mainly by the Schrock group 6 ). Owing to the low oxophilicity of ruthenium compared to those of molybdenum and tungsten, the ruthenium metathesis catalysts (commonly known as Grubbs' catalysts) are more tolerant towards many polar functional groups and residual impurities, as well as to water 7 . Therefore, these catalysts are the catalysts of choice in highly functional organic chemistry transformations as well as for the majority of metathesis polymerizations carried out today. Catalysts G1 (first generation) and G3 (third generation) are the most widely used ruthenium initiators for ring-opening metathesis polymerization (ROMP). In comparison to the G1 initiator, the third-generation catalyst G3 exhibits very fast initiation and propagation rates, and thereby gives polymers with very narrow dispersities and an excellent control over their molecular weights. Owing to its superior stability as well as the favourable polymerization kinetics, the third-generation Grubbs' catalyst G3 was used for this work. ROMP is a polymerization technique that uses the metathesis of cyclic olefins to synthesize linear polymers. Depending on the structure of the monomer, such polymerizations can be controlled perfectly to give polymers with a narrow molecular weight distribution and a controlled average molecular weight. Ring-strained monomers, li...

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Catalytic living ring-opening metathesis polymerization

Nagarkar

Kilbinger

2015

Nature Chem

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“…Within this category olefin metathesis (mainly as ringclosing metathesis, cross-metathesis and ring-opening metathesis polymerization (ROMP)), has won a leading position owing to its success in yielding various natural products, specialty polymers, pharmaceuticals and otherwise hard-to-get organic compounds [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

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First FT-Raman and 1H NMR comparative investigations in ring opening metathesis polymerization

Ding

Monsaert

Drozdzak

et al. 2009

Vibrational Spectroscopy

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“…One possible solution would be the development of an efficient heterogeneous catalysts that is highly active (TON and TOF), stable (minimum recycling and leaching) and tolerant to functional groups. Despite numerous efforts in this area (involving permanent grafting of Ru-NHC complexes on various supports [7][8][9][10] or other immobilization strategies [11] ), heterogeneous catalysts has not fulfilled the aforementioned requirements. Recently, tailored made organic-inorganic materials have proved to be an alternative and advantageous route towards highly active and well-defined heterogeneous catalysts.…”

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confidence: 99%