<scp>CR</scp> composites with improved processing safety crosslinked via Heck's reaction

Dziemidkiewicz, Anna; Maciejewska, Magdalena

doi:10.1002/app.49922

Cited by 3 publications

(2 citation statements)

References 27 publications

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“…The Heck reaction of halogenated aromatics with olefins is among the most direct effective methods for forming C-C bonds and has been extensively applied for the synthesis of drugs and intermediates, natural products, and functional materials. [1][2][3][4] Since the discovery of the Heck reaction, reaction selectivity, catalyst types, and catalytic mechanisms have been intensively studied. [5][6][7] Among the investigated catalysts, traditional homogeneous palladium catalysts show excellent catalytic activity but also have some limitations such as air-sensitivity, poor recyclability and reusability, and cumbersome post-treatment.…”

Section: Introductionmentioning

confidence: 99%

Continuous-flow Heck coupling reactions catalyzed by Pd complexes of amidoxime fibers

Xie

Zhang

et al. 2023

Journal of Chemical Research

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Improving production efficiency and developing green catalytic systems are key issues for applying Heck coupling reactions in the chemical industry. In this study, an amidoxime-fiber-supported Pd catalyst is prepared from polyacrylonitrile fiber, hydroxylamine hydrochloride, and PdCl2. The morphology and structure of amidoxime-fiber-supported Pd are characterized by scanning electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectrometer, X-ray diffraction, and inductively coupled plasma-optical emission spectrometer. A packed-bed flow reactor is designed and employed for catalysis of the Heck reaction of iodobenzene and styrene based on the amidoxime-fiber-supported Pd catalyst. The effects of reaction temperature, flow rate, cycle time, and reactant concentration on the conversion and yield are investigated. The results show that the optimal conditions for the continuous-flow single reactor are 70 °C, iodobenzene concentration of 30 mmol L−1 in a solution of N,N-dimethylformamide (100 mL) under continuous flow at a flow rate of 2 mL min−1. The catalyst showed good activity and stability after a continuous operation time of 50 h, with catalytic activity 2.21 times higher than that obtained with traditional batch reaction. Furthermore, we have established a new flow reaction system based on the numbering-up of reactors with a parallel connection. The catalytic efficiency of four parallel reactors is four times higher than that of a single reactor. Kinetic studies reveal that the reaction has low activation energy (8.8771 kJ mol−1), indicating that amidoxime-fiber-supported Pd has good catalytic activity. This research provides an alternative pathway for highly efficient Heck coupling in continuous flow.

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Section: Introductionmentioning

confidence: 99%

Continuous-flow Heck coupling reactions catalyzed by Pd complexes of amidoxime fibers

Xie

Zhang

et al. 2023

Journal of Chemical Research

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“…In our previous studies [ 25 , 26 , 27 , 28 ], we reported the activity of metal acetylacetonates with different transition metals in the presence of triethanolamine (TEOA) as curing agents for CR. The crosslinking of CR with the proposed curing systems was proven to proceed in accordance with the mechanism of Heck reaction [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

Manganese and Nickel Acetylacetonates as Curatives for Chloroprene Rubber Based on Heck’s Reaction

Dziemidkiewicz

Maciejewska

2021

Materials

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The commonly used curing system for chloroprene rubber (CR) is a combination of two metal oxides, such as magnesium oxide (MgO) and zinc oxide (ZnO). Application of MgO and ZnO enables to obtain a good balance between processability of rubber compounds and mechanical properties of the vulcanizates. Despite high activity in crosslinking reactions, ZnO is classified as ecotoxic to aquatic organisms, thus environmental legislation requires its quantity in technology to be limited. In our studies more environmentally friendly curing systems were applied, which enabled eliminating ZnO from CR compounds. These curing systems consisted of manganese acetylacetonate (Mn(acac)) or nickel acetylacetonate (Ni(acac)) and triethanolamine (TEOA) used as a base necessary to perform Heck’s reaction. Both metal acetylacetonates exhibited high activity in crosslinking reactions, which was confirmed by a great torque increment during rheometric measurements and high degree of elastomer crosslinking. The type of metal acetylacetonate and the amount of TEOA seemed to have less influence on the efficiency of the curing system than the filler used. Rubber compounds filled with carbon black (CB) were characterized by definitely shorter optimal vulcanization times and higher degree of crosslinking compared to CR composites filled with nanosized SiO2. Moreover, application of the proposed curing systems allowed to obtain CR vulcanizates with mechanical properties comparable with the benchmarks cured with metal oxides.

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Quest for Sustainable Curatives for Chloroprene Rubber: A Comprehensive Review

Sarkar

Fujii

Abe

et al. 2022

Rubber Chemistry and Technology

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Chloroprene rubber (CR) is one of the most versatile synthetic rubbers suitable for numerous industrial applications. For years, zinc oxide (ZnO) has been satisfactorily used as the vulcanization activator for CR, typically with organic accelerator(s). Ethylene thiourea (ETU) is the most widely used accelerator, offering the best balance between cost and performance in CR vulcanizates. Recently, the ZnO level in rubber compounds has become a pressing issue because of its harmful environmental impacts. ETU is classified as a substance of potentially serious health risks. It is therefore imperative to identify sustainable crosslinking additives for CR from both technical and commercial standpoints. The key purpose of this review is to collate the significant lines of technological advances made to identify proecological curative options for CR and update the information up to the current year. In preparation for this review, pertinent scholarly articles on the curing of CR, published in scientific journals mainly in the past two decades, were assessed. Since the scope of this review is to capture the significant technical efforts available in the public domain, the reference list is therefore not necessarily an exhaustive one. Reports dealing with proprietary chemicals or undisclosed technical strategies are beyond the purview of this review.

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CR composites with improved processing safety crosslinked via Heck's reaction

Cited by 3 publications

References 27 publications

Continuous-flow Heck coupling reactions catalyzed by Pd complexes of amidoxime fibers

Continuous-flow Heck coupling reactions catalyzed by Pd complexes of amidoxime fibers

Manganese and Nickel Acetylacetonates as Curatives for Chloroprene Rubber Based on Heck’s Reaction

Quest for Sustainable Curatives for Chloroprene Rubber: A Comprehensive Review

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