Polymer-Supported Palladium Complex Research Articles

A Review on the Development of Polymer Supported Heterogeneous Palladium Materials for Organic Synthesis and Electrochemical Applications

Abstract:: This comprehensive review explores the advancements in catalytic transformation, focusing on the use of heterogeneous catalytic systems with a particular emphasis on polymeric-supported palladium (Pd) complexes. This study explores the limitations associated with conventional homogeneous reagents, emphasizes the transition to eco-friendly catalytic systems, and emphasizes the importance of Pd nanoparticles. These nanoparticles are particularly noteworthy for their distinctive properties, including elevated catalytic activity, making them promising for various applications in organic synthesis. The review thoroughly examines the design and synthesis of heterogeneous catalysts, emphasizing the crucial selection of safe and recyclable supports to augment the longevity and reusability of metallic catalysts. Diverse polymer varieties, including polystyrene (PS), polyethylene (PE), polyacrylate derivatives, polyethylene glycol (PEG), and grafted polymers, are investigated as viable supports for Pd complexes. The authors intricately describe the synthesis techniques for these polymer-supported Pd catalysts and furnish illustrative examples showcasing their effectiveness in organic transformation. This comprehensive review additionally highlights the synthesis of polymer-supported palladium (Pd) materials and discusses their applications in electrochemistry. The focus extends to the electrocatalytic properties of Pdbased polymeric nanomaterials, showcasing their effectiveness in glucose sensing, hydrogen peroxide detection, and the sensing of other biological analytes. Furthermore, the catalytic capabilities of Pd nanoparticles in various electrochemical applications, including wastewater treatment and electrochemical capacitors, are explored. Integrating polymer-supported Pd materials into these electrochemical processes underscores their versatility and potential contributions to advancements in catalysis and electrochemical sensing. Catalytic applications featuring polymer-supported palladium complexes with polymeric ligands in organic synthesis processes use the Sonogashira reaction, Suzuki-Miyaura coupling, Heck reaction, Catalytic asymmetric transformations, etc. The subsequent section of the paper focuses on the creation of polymeric palladium complexes, achieved by the complexation of polymeric ligands with palladium precursors. It delves into noteworthy examples of catalytic processes employing polymer-supported palladium complexes featuring polymeric ligands, emphasizing distinct polymers, such as PS, PE, polyacrylate derivatives, PEG, and grafting polymers. The review concludes by exploring catalytic asymmetric transformations using chiral palladium complexes immobilized on polymer supports and discusses various chiral ligands and their immobilization on polymer supports, emphasizing their application in asymmetric allylic alkylation. The review furnishes a comprehensive summary of recent advancements, challenges, and prospective avenues in catalytic oxidation facilitated by polymer- supported palladium catalysts with electrochemical applications.

Amidoxime modified PAN supported palladium complex: A greener and efficient heterogeneous catalyst for heck reaction

Development of a facile and greener approach for Heck reaction using a modified PAN supported palladium catalyst is described. The preparation of the catalyst involves a simple process through amidoxime modification of nitrile group in Polyacrylonitrile (PAN), followed by the complexation with Palladium chloride (PdCl2). The resulting supported catalyst was characterized by spectroscopic analyses and further by computational studies. This polymer supported Palladium complex displayed excellent catalytic activity in Heck coupling reaction of a series of activated alkenes and aryl halides and afforded the corresponding coupling products upto 96% isolated yield. After the reaction, the catalyst was easily recovered by simple filtration and recycled with excellent stability and activity even after 5 runs. This is the first report on the use of amidoxime functionalized PAN- Palladium (II) complex as a heterogeneous catalyst in Heck coupling reaction.

Polymer supported palladium complex as a reusable catalyst for Suzuki coupling

Novel, simple and efficient catalytic system based on a polymer supported Pd complex of 2,6-bis(benzimidazolyl)pyridine, Pd(PSBBP)Cl2, was found to be highly active for Suzuki–Miyaura cross-coupling of aryl halides with phenylboronic acids under mild conditions. The catalyst was characterized by CHN analyses, thermogravimetric analyses, BET surface area measurements, ICP-OES, FT-IR and electronic spectral studies. The effect of solvent, base, temperature and catalyst concentration on the coupling reaction of iodobenzene with phenylboronic acid was also investigated. A variety of functional groups are tolerated. The novel catalyst could be recovered in a facile manner from the reaction mixture and could be reused up to seven times without significant loss of catalytic activity.

PdCl2 on modified poly(styrene-co-maleic anhydride): A highly active and recyclable catalyst for the Suzuki–Miyaura and Sonogashira reactions

The Suzuki–Miyaura and Sonogashira coupling were performed using a new, efficient, reusable and recyclable polymer-supported palladium catalyst. Poly(styrene-co-maleic anhydride) as polymer-support is modified with 2-aminothiazole. PdCl2 was immobilized on this prepared support and its appearance was confirmed by scanning electron microscopy (SEM), energy dispersive spectroscopy analysis of X-rays (EDAX), inductively coupled plasma (ICP) analysis, and FT-IR techniques. In addition, a quantitative description for metal–ligand interactions in the aforementioned polymer-supported palladium complex is investigated by performing theoretical calculations using density functional theory techniques.

Tetrazole Functionalized Polymer Supported Palladium Complex: An Efficient and Reusable Catalyst for the Room-Temperature Suzuki Cross-Coupling Reaction

Tetrazole functionalized polymer supported palladium complex was synthesized and characterized. The catalytic activity has been evaluated for the room-temperature Suzuki cross-coupling reaction proving an excellent performance in terms of both activity and recyclability. Various aryl bromides were coupled with aryl boronic acids in EtOH/H2O mixed solvents, under air and in presence of 0.5 mol% of the catalyst to afford corresponding cross-coupled products in high yields. Furthermore, the heterogeneous catalyst can be readily recovered by simple filtration and reused for several times only with slightly decrease in its activity.

Hydrogenation of olefins by polymer-bound palladium(II) Schiff base catalyst

Chloromethylated poly(styrene-divinylbenzene) was modified into coordinating Schiff base bearing ligand which was subsequently complexed with palladium chloride and activated by using sodium borohydride. The polymer-supported palladium complex and activated catalyst were characterized by various techniques such as elemental analysis, X-ray photoelectron spectroscopy, atomic absorption spectroscopy, IR, far IR spectral studies, SEM and thermogravimetric analysis. Surface area measurements by BET method and swelling studies with different solvents for the catalyst were also carried out. Catalytic activity towards hydrogenation of 1-hexene, 1-heptene, 1-octene, cyclohexene, norbornadiene (nbd) and 1,5-cyclooctadiene (1,5-cod) was assessed. The influence of variation in temperature, pressure, concentration of the catalyst as well as the substrate and the nature of the solvent on the rate of the reaction was studied for a few olefins. Recycling ability of the catalyst was also evaluated.

A new homogeneous polymer support based on syndiotactic polystyrene and its application in palladium-catalyzed Suzuki–Miyaura cross-coupling reactions

Soluble syndiotactic polystyrene-supported triphenylphosphine (sPS–TPP) was synthesized by reacting borylated syndiotactic polystyrene with (4-bromophenyl)diphenylphosphine. A palladium catalyst, supported on sPS–TPP, effectively catalyzed Suzuki–Miyaura coupling reactions of aryl halides under homogeneous conditions. The polymer-supported palladium complex was recovered quantitatively by adding an equal volume of poor solvent to the polymer, and coupling products could be easily isolated by evaporating the solvents. The recovered polymer complex was reused several times without significant loss of activity.

Heterogeneous Asymmetric Aquacatalysis with Polymer-Supported Palladium Complexes

Catalytic asymmetric organic transformations performed in aqueous media with immobilized chiral palladium and rhodium complexes are reviewed. Amphiphilic polystyrene-poly(ethylene glycol) graft co-polymer (PS-PEG) resin-supported MOP, boxax, BINAP, and an imidazoindole phosphine ligands were designed and prepared with a view to use them in asymmetric catalysis under aqueous and heterogeneous conditions. Several carbon-hydrogen, carbon-carbon, carbon-nitrogen, and carbon-oxygen bond forming reactions were achieved in water with high stereoselectivity and recyclability to meet the green chemical requirements.

Stille coupling reactions catalysed by a polymer supported palladium complex

The coupling between aryl iodides and bromides with organostannanes (Stille reaction) has been investigated in the presence of a polymer supported palladium catalyst. The reaction could be performed in air without any activating ligand and with non-dried solvents. The catalyst, which acts by releasing controlled amounts of soluble active species, could be recycled several times in the coupling between Sn(CH 3) 4 or n Bu 3SnPh with iodoarenes or activated bromoarenes.

Recent Progress in Polymeric Palladium Catalysts for Organic Synthesis

AbstractFor Abstract see ChemInform Abstract in Full Text.

Polymer—Supported Palladium N‐Heterocyclic Carbene Complexes: Long Lived Recyclable Catalysts for Cross‐Coupling Reactions.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Rapid Microwave‐Promoted Cross‐Coupling Reaction of Aryl Bromides with Aryl Boronic Acids and Sodium Tetraphenylborate Catalyzed by a Reusable Polymer‐Supported Palladium Complex

AbstractA variety of biaryls were prepared in a rapid and highly efficient manner via the cross‐coupling reaction of aryl bromides with aryl boronic acids or sodium tetraphenylborate in toluene, aqueous potassium carbonate and in the presence of a polymer‐supported palladium(II) catalyst under microwave irradiation condition. The supported catalyst was prepared directly from a commercial Merrifield resin and ultrasound dramatically accelerated the preparation of the catalyst. The polymeric catalyst can be easily separated from a reaction mixture and reused five times without decrease in activity. This suggests that a comparatively stable palladium phosphine complex is the reacting species in this special case. The reaction can be performed equally well using microwave and conventional heating, showing that microwave irradiation accelerates the reaction tremendously and in higher yields.

Polymer supported palladium N-heterocyclic carbene complexes: long lived recyclable catalysts for cross coupling reactions

Polymer supported palladium complexes, containing a pyridyl bis N-heterocyclic carbene ligand system derived from isonicotinic acid, provide highly stable catalysts for Heck and Suzuki cross coupling reactions. These heterogenous catalysts can be recycled ⩾14 times with no loss of activity.

Experimental design and the optimization of a polymer supported palladium complex for use in the Heck reaction

Optimization of the Heck reaction of 4-bromoacetophenone with styrene by a polymer supported, sulfur-containing palladacycle, varying 6 factors at a total of 28 different levels, corresponding to 5760 different possibilities was undertaken. Conversion improved from 34%, with large observable leaching to 88% with no leaching. This was accomplished using a Design of Experiments approach facilitated by the Statistical Design Package, MODDE 7.0 TM.

Effect of active site distribution on liquid-phase olefin hydrogenation over polymer-supported palladium complex

Chloromethylated polystyrene beads with different distributions have been prepared and phosphinated. PdCl2 was supported on the phosphinated supports to give polymer-supported Pd complex catalysts with different active site distributions. The effect of active site distribution on catalytic activity was investigated in the hydrogenation of olefins.