Novel Thione-Thiol Rearrangement of Dithiocarbonic Acid O-(2,2,6,6-Tetramethylpiperidin-1-yl) Ester in the Context of Controlled Radical Polymerization

Nesvadba, Peter; Bugnon, Lucienne; Wagner, Trixie

doi:10.2533/chimia.2010.56

Cited by 4 publications

(1 citation statement)

References 22 publications

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“…Since HALS can, at best, only rarely participate in the JKZG cycle (Scheme ), we consider in Scheme a number of literature proposals for aminyl (and hence secondary amine) formation, including Barton’s pathway via a trioxide (reactions 23 and 24), , Turro’s mechanism via an amine hydroperoxide (reactions 25 and 26), and some reactions with formyl-derived radicals, as suggested by Gerlock and co-workers for HALS-stabilized acrylic/melamine coatings (reactions 27–31). , …”

Section: Resultsmentioning

confidence: 99%

New Insights into the Mechanism of Amine/Nitroxide Cycling during the Hindered Amine Light Stabilizer Inhibited Oxidative Degradation of Polymers

2012

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High-level ab initio molecular orbital theory calculations are used to identify the origin of the remarkably high inhibition stoichiometric factors exhibited by dialkylamine-based radical-trapping antioxidants. We have calculated the free energy barriers and reaction energies at 25, 80, and 260 °C in the gas phase and in aqueous solution for a broad range of reactions that might, potentially, be involved in amine/nitroxide cycling, as well as several novel pathways proposed as part of the present work, including that of N-alkyl hindered amine light stabilizer activation. We find that most of the literature nitroxide regeneration cycles should be discarded on either kinetic or thermodynamic grounds; some are even inconsistent with existing experimental observations. We therefore propose a new mechanistic cycle that relies on abstraction of a β-hydrogen atom from an alkoxyamine (R(1)R(2)NOCHR(3)R(4)). Our results suggest that this cycle is energetically feasible for a range of substrates and provides an explanation for previously misinterpreted or unexplained experimental results. We also explore alternative mechanisms for amine/nitroxide cycling for cases where the alkoxyamines do not possess an abstractable β-hydrogen.

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Section: Resultsmentioning

confidence: 99%

New Insights into the Mechanism of Amine/Nitroxide Cycling during the Hindered Amine Light Stabilizer Inhibited Oxidative Degradation of Polymers

2012

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Radical Polymerization in Industry

Nesvadba

2012

Encyclopedia of Radicals in Chemistry, Biology and Materials

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The position of radical polymerization (RP) in the context of polymer industry is highlighted. The mechanistic steps of RP are discussed from an industrial point of view. An overview of industrial initiators including photoinitiators, chain transfer agents, and monomer stabilizers is given. The most important polymerization processes with focus on emulsion polymerization (EP) and dispersion polymers as well as types of polymerization reactors are presented. The progress of controlled RP toward commercialization is reviewed.

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Controlled/Living Radical Polymerization Mediated by Stable Organic Radicals

Nesvadba

2013

Fundamentals of Controlled/Living Radical Polymerization

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The development of stable-radical mediated polymerization (SRMP) from its origins with focus on nitroxide-mediated radical polymerization (NMP) is reviewed. The underlying persistent radical effect, mechanistic steps, fundamental kinetic equations and side reactions of NMP are discussed. The most important nitroxides and alkoxyamine initiators for NMP are presented, along with the parameters influencing the rate constants of cleavage and reformation of alkoxyamines. Applications of NMP for synthesis of complex polymeric structures and in industry are shown, and advances in nitroxide-mediated photopolymerization (NMPP) are discussed. SRMP with the most important non-nitroxide stable organic radicals as well as the organometallic-mediated radical polymerization (OMRP) are briefly mentioned.

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Novel Thione-Thiol Rearrangement of Dithiocarbonic Acid O-(2,2,6,6-Tetramethylpiperidin-1-yl) Ester in the Context of Controlled Radical Polymerization

Cited by 4 publications

References 22 publications

New Insights into the Mechanism of Amine/Nitroxide Cycling during the Hindered Amine Light Stabilizer Inhibited Oxidative Degradation of Polymers

New Insights into the Mechanism of Amine/Nitroxide Cycling during the Hindered Amine Light Stabilizer Inhibited Oxidative Degradation of Polymers

Radical Polymerization in Industry

Controlled/Living Radical Polymerization Mediated by Stable Organic Radicals

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