Recent Developments in the Immobilization of Palladium Complexes on Renewable Polysaccharides for Suzuki–Miyaura Cross-Coupling of Halobenzenes and Phenylboronic Acids

Wolfson, Adi; Levy‐Ontman, Oshrat

doi:10.3390/catal10010136

Cited by 20 publications

(11 citation statements)

References 116 publications

(179 reference statements)

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“…To that end, polysaccharides, which constitute the most prevalent form of the biopolymers and the most abundant organic material on earth, have recently been used to immobilize different metal catalysts as complexes or nanoparticles. Of note are the palladium-based catalysts, which have been used mainly in the Suzuki cross-coupling reaction [ 34 , 35 ] but also in other coupling reactions [ 36 ], in amination and in hydrogenation [ 37 ]. However, polysaccharides-based palladium catalysts for the aerobic oxidation of alcohols have not been proposed.…”

Section: Introductionmentioning

confidence: 99%

Green Procedure for Aerobic Oxidation of Benzylic Alcohols with Palladium Supported on Iota-Carrageenan in Ethanol

2021

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The search for selective heterogeneous catalysts for the aerobic oxidation of alcohols to ketones and aldehydes has drawn much attention in the last decade. To that end, different palladium-based catalysts have been proposed that use various organic and inorganic supports. In addition, supports that originate from a biological and renewable source that is also nontoxic and biodegradable were found to be superior. We heterogenized palladium chloride or acetate complexes with triphenylphosphine trisulfonate on iota-carrageenan xerogel by simple mixing of the complex and the polysaccharide in water. The resulting polysaccharide-catalyst mixture then underwent deep freeze and lyophilization, after which the catalyst was characterized by TEM, XPS and SEM-EDS and tested in aerobic oxidation. The new heterogeneous catalysts were successfully used for the first time in the aerobic oxidation of benzylic alcohols. Moreover, they were easily removed from the reaction mixture and recycled, yielding an increase in activity with each subsequent reuse. As determined by TEM and XPS, the reduction in palladium and the formation of nanoparticles during the reaction in ethanol yielded more active species and, therefore, higher conversion rates. A SEM-EDS analysis indicated that the palladium was thoroughly dispersed in the xerogel catalysts. Moreover, the xerogel catalyst was observed to undergo a structural change during the reaction. To conclude, the new heterogeneous catalyst was prepared by a simple and straightforward method that used a non-toxic, renewable and biodegradable support to yield an active, selective and recyclable heterogeneous system.

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Section: Introductionmentioning

confidence: 99%

Green Procedure for Aerobic Oxidation of Benzylic Alcohols with Palladium Supported on Iota-Carrageenan in Ethanol

2021

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“…The hydroxyl groups in all polysaccharides are responsible for the formation of intra‐ and inter‐molecular hydrogen bonds, whereas the incorporation of amine or sulfate groups in their structure may result in the formation of stronger chemical bonds. [ 36 ] In the conducted research, the hydroxyl groups of cellulose fibers were converted to sulfate. Therefore, they can be considered as incorporated cites for chemical bonding of palladium with the support.…”

Section: Resultsmentioning

confidence: 99%

Preparation and characterization of cellulose sulfate/Pd nanocatalsysts with remarkable efficiency for Suzuki–Miyaura reaction

Jokar

Naeimi

Bidhendi

2021

Applied Organom Chemis

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Heterogeneous catalysis with noble metal NPs are quite attractive due to unique surface chemistry and tuneable physicochemical properties. In this work, an efficient and simple method was used to synthesize palladium nanoparticles supported on cellulose sulfate. The resulted composites were characterized using various techniques such as X‐ray powder diffraction (XRD), FT‐IR, energy dispersive X‐ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) to verify the chemical structure and morphological properties of nanocatalysts. Next, the synthesized catalyst was utilized in Suzuki–Miyaura reaction between aryl bronic acid and different aryl halides. The catalysis reaction was carried out under atmospheric pressure where high efficiency, unique and simple work‐up procedure as well as excellent yields were achieved.

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“…It has been demonstrated for reported systems that the support clearly influences the catalytic performance. 9,10,11,12,13 In this view, TiO 2 , exhibiting good thermal, mechanical and chemical stabilities can be regarded as a promising candidate. Therefore we particularly followed here the evolution of TiO 2 -heterogenized palladium complexes of the type PdBr 2 (L∩L), in which L∩L is a chelating bis(benzimidazol-2ylidene) ligand.…”

Section: Introductionmentioning

confidence: 99%

From the grafting of NHC-based Pd(II) complexes onto TiO2 to the in situ generation of Mott-Schottky heterojunctions: The boosting effect in the Suzuki-Miyaura reaction. Do the evolved Pd NPs act as reservoirs?

Tovar

Rataboul

Djakovitch

2021

Journal of Catalysis

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The assumption that the real active species involved in the Suzuki-Miyaura reaction are homogeneous, heterogeneous or both is often proposed. However a lack of characterization of the true catalytic entities and their monitoring makes assumptions somewhat elusive.Here, with the aim of getting new insights into the formation of active species in the Suzuki-Miyaura reaction, a family of palladium(II) complexes bearing bis(NHC) ligands was synthesized for immobilization at the surface of TiO 2 .The studies reveal that once the complexes are anchored onto TiO 2 , the mechanism governing the catalytic reaction is different from that observed for the non-anchored complexes. All complexes evolved to Pd NPs at the surface of TiO 2 under reaction conditions and released Pd species in the liquid phase. Also, this reactivity was boosted by the in situ generation of Mott-Schottky heterojunctions, opening new routes towards the design of heterogenized catalysts for their further implementation in reverse-flow reactors.

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Recent Developments in the Immobilization of Palladium Complexes on Renewable Polysaccharides for Suzuki–Miyaura Cross-Coupling of Halobenzenes and Phenylboronic Acids

Cited by 20 publications

References 116 publications

Green Procedure for Aerobic Oxidation of Benzylic Alcohols with Palladium Supported on Iota-Carrageenan in Ethanol

Green Procedure for Aerobic Oxidation of Benzylic Alcohols with Palladium Supported on Iota-Carrageenan in Ethanol

Preparation and characterization of cellulose sulfate/Pd nanocatalsysts with remarkable efficiency for Suzuki–Miyaura reaction

From the grafting of NHC-based Pd(II) complexes onto TiO2 to the in situ generation of Mott-Schottky heterojunctions: The boosting effect in the Suzuki-Miyaura reaction. Do the evolved Pd NPs act as reservoirs?

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