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Keywords = boomerang catalyst

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18 pages, 9018 KB  
Article
Preparation of Ruthenium Olefin Metathesis Catalysts Immobilized on MOF, SBA-15, and 13X for Probing Heterogeneous Boomerang Effect
by Artur Chołuj, Wojciech Nogaś, Michał Patrzałek, Paweł Krzesiński, Michał J. Chmielewski, Anna Kajetanowicz and Karol Grela
Catalysts 2020, 10(4), 438; https://doi.org/10.3390/catal10040438 - 17 Apr 2020
Cited by 15 | Viewed by 5929
Abstract
Promoted by homogeneous Ru-benzylidene complexes, the olefin metathesis reaction is a powerful methodology for C-C double bonds formation that can find a number of applications in green chemical production. A set of heterogeneous olefin metathesis pre-catalysts composed of ammonium-tagged Ru-benzylidene complexes 4 (commercial [...] Read more.
Promoted by homogeneous Ru-benzylidene complexes, the olefin metathesis reaction is a powerful methodology for C-C double bonds formation that can find a number of applications in green chemical production. A set of heterogeneous olefin metathesis pre-catalysts composed of ammonium-tagged Ru-benzylidene complexes 4 (commercial FixCat™ catalyst) and 6 (in-house made) immobilized on solid supports such as 13X zeolite, metal-organic framework (MOF), and SBA-15 silica were obtained and tested in catalysis. These hybrid materials were doped with various amounts of ammonium-tagged styrene derivative 5—a precursor of a spare benzylidene ligand—in order to enhance pre-catalyst regeneration via the so-called release-return “boomerang effect”. Although this effect was for the first time observed inside the solid support, we discovered that non-doped systems gave better results in terms of the resulting turnover number (TON) values, and the most productive were hybrid catalysts composed of 4@MOF, 4@SBA-15, and 6@SBA-15. Full article
(This article belongs to the Special Issue SBA-15 and Catalysis)
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19 pages, 9260 KB  
Article
Polystyrene-Supported Acyclic Diaminocarbene Palladium Complexes in Sonogashira Cross-Coupling: Stability vs. Catalytic Activity
by Vladimir N. Mikhaylov, Viktor N. Sorokoumov, Denis Martin Liakhov, Alexander G. Tskhovrebov and Irina A. Balova
Catalysts 2018, 8(4), 141; https://doi.org/10.3390/catal8040141 - 2 Apr 2018
Cited by 45 | Viewed by 7411
Abstract
Two types of immobilized on the amino-functionalized polystyrene-supported acyclic diaminocarbene palladium complexes (ADC-PdII) are investigated under Sonogashira cross-coupling conditions. Depending on substituents in the diaminocarbene fragment immobilized ADC-PdII, systems are found to have different catalytic activity and stability regarding [...] Read more.
Two types of immobilized on the amino-functionalized polystyrene-supported acyclic diaminocarbene palladium complexes (ADC-PdII) are investigated under Sonogashira cross-coupling conditions. Depending on substituents in the diaminocarbene fragment immobilized ADC-PdII, systems are found to have different catalytic activity and stability regarding Pd-leaching. PdII-diaminocarbenes possessing protons at both nitrogen atoms smoothly decompose into Pd0-containing species providing a catalytic “cocktail system” with high activity and ability to reuse within nine runs. Polymer-supported palladium (II) complex bearing NBn–Ccarbene–NH-moiety exhibits greater stability while noticeably lower activity under Sonogashira cross-coupling. Four molecular ADC-PdII complexes are also synthesized and investigated with the aim of confirming proposed base-promoted pathway of ADC-PdII conversion through carbodiimide into an active Pd0 forms. Full article
(This article belongs to the Special Issue Solid-Supported Reagents in Palladium-Catalyzed Transformations)
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13 pages, 14316 KB  
Article
Application of “Boomerang” Linear Polystyrene-Stabilized Pd Nanoparticles to a Series of C-C Coupling Reactions in Water
by Atsushi Ohtaka, Toshiyuki Okagaki, Go Hamasaka, Yasuhiro Uozumi, Tsutomu Shinagawa, Osamu Shimomura and Ryôki Nomura
Catalysts 2015, 5(1), 106-118; https://doi.org/10.3390/catal5010106 - 9 Feb 2015
Cited by 29 | Viewed by 8895
Abstract
The application of a catch-and-release system for soluble Pd species between water (reaction medium) and polystyrene (polymer support) was examined in the Suzuki coupling reaction with 2-bromothiophene and the Heck reaction with styrene or bromobenzene. Although a slight increase in particle size was [...] Read more.
The application of a catch-and-release system for soluble Pd species between water (reaction medium) and polystyrene (polymer support) was examined in the Suzuki coupling reaction with 2-bromothiophene and the Heck reaction with styrene or bromobenzene. Although a slight increase in particle size was observed by TEM after re-stabilization of the Pd species on linear polystyrene, no agglomeration was observed. Full article
(This article belongs to the Special Issue Metal Catalysts Recycling and Heterogeneous/Homogeneous Catalysis)
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