Suzuki Reaction In Aqueous Media Research Articles

Selective capture of Pd(II) from aqueous media by ion-imprinted dendritic mesoporous silica nanoparticles and re-utilization of the spent adsorbent for Suzuki reaction in water

The development of highly efficient adsorptive material for the selective capture of Pd(II), and re-utilization of spent Pd(II)-loaded adsorbent as an efficient catalyst for organic synthesis are of great significance, but challenging. Particularly, the heterogeneous palladium-catalyzed Suzuki reaction in aqueous media is much more challenging than that of homogeneous. Herein, several novel Pd(II) ion-imprinted polymers (PIIPs) based on dendritic fibrous silica particles are constructed by surface ion imprinting technology (SIIT), using Schiff base and pyridine groups functionalized organosilicon as functional monomer. The PIIP-3 prepared by 3 g of functional monomer exhibits the best adsorption performance, and shows ultrafast (10 min) and selective capture of Pd(II) with high uptake capacity (382.5 mg/g). Moreover, the waste Pd(II) loaded PIIP-3 (PIIP-3-Pd) can serve as a catalyst towards the Suzuki reaction in water, affording 94.2 % yield of the desired product. Interestingly, the PIIP-3-Pd can be reused 12 times without an appreciable decrease in catalytic activity, which is probably due to the imprinted cavity and specific recognition site of PIIP-3 can match and recapture Pd active species in a complex catalytic environment. Thus, this work demonstrates huge potentials of SIIT to enhance the selectivity of adsorption process and increase the lifetime of catalysts.

Reusable Proline-Containing Bimetallic Pd–Ni(Co, Cu, Fe)–Pro/Al2O3 Catalysts for Suzuki Reaction in Water

Bimetallic proline-containing composites Pd–Ni(Co, Cu, Fe)–Pro/Al2O3, due to the synergistic effect, exhibit high catalytic activity in the Suzuki reaction in aqueous media, which makes it possible to reduce the amount of expensive Pd to 10–2 mol %. New catalysts are easily regenerated from the reaction mixture and can be reused up to 5 times without losing activity.

Polymetallic magnetic palladium catalysts for the Suzuki reaction in aqueous media

Polymetallic magnetic palladium catalysts for the Suzuki reaction in aqueous media

Palladium supported on N-Heterocyclic carbene functionalized hydroxyethyl cellulose as a novel and efficient catalyst for the Suzuki reaction in aqueous media

Bearing an intrinsic green nature, biopolymers are expected to serve as ideal alternatives in the sustainable conversion process. In this paper, a N-Heterocyclic carbene functionalized hydroxyethyl cellulose supported palladium catalyst (HEC-NHC-Pd) has been successfully prepared through a surface functionalization approach. The as-prepared catalyst was characterized through TEM, CP/MAS 13C NMR, and XPS analyses, etc. The new and eco-friendly catalyst was effectively employed in Suzuki reactions in ethanol aqueous solution. Dependent on dual coordination sites (OH and N-Methylimidazole) binding to the active component (Pd), the palladium complex exhibited high stability and low metal leaching (<1%). Additionally, the environmental friendliness catalyst could be retrieved through simple centrifugation within a few cycles. This study also offers a new pathway for the application of such biopolymer surface functionalization in organic transformations.

The kinetics and mechanism of polymer‐based NHC‐Pd‐pyridine catalyzed heterogeneous Suzuki reaction in aqueous media

AbstractOne of the most important challenges of the Suzuki reaction is a green synthesis of reaction products. In terms of economy and ecology, the Suzuki reaction details must be characterized for the industrial‐scale Suzuki reaction processes. In this paper, for the first time, a kinetic and mechanistic study on the Suzuki reaction catalyzed with hydrogel‐supported PEPPSI (pyridine‐enhanced precatalyst preparation stabilization (and) initiation) type NHC‐Pd‐pyridine composite has been investigated. To determine the rate‐limiting step, the effects of reactants and experimental conditions on the heterogeneous Suzuki reaction have been experimentally defined. The experimental results demonstrated that it is possible to reach 100% yield under the optimum reaction conditions, which were found as 75 × 10−3 mol/L of phenylboronic acid (FBA), 50 × 10−3 mol/L of bromoacetophenone (Brac), 125 × 10−3 mol/L of K2CO3, 1 g/L of catalyst, 80°C of reaction temperature, 400 rpm of mixing rate, and 3 h of reaction time. The transmetalation step in the cycle was defined as the rate‐limiting step. On the basis of kinetic results, a mathematical reaction rate expression was presented assuming the steady‐state approach to steps of the catalytic cycle. The activation energy (Ea) of the reaction was estimated to be 34.88 kJ/mol.

Effective bimetallic composite catalysts for the synthesis of arylated furans and thiophenes in aqueous media

N-(4,6-Dimethylpyrimidin-2-yl)-5-phenylisoxazole-3-carboxamide was used as a ligand for obtaining bimetallic boron-containing heterogeneous catalysts Pd–Ni(Co)–B–L (Ni(Co):Pd = 9:1). The obtained composites were highly active as catalysts of Suzuki reaction in aqueous media, allowing to develop convenient methods for the synthesis of heterobiaryls containing furyl and thienyl rings.

3,5-[5-Arylisoxazol-3-yl(4,5-dichloroisothiazol-3-yl)]-substituted 1,2,4- and 1,3,4-oxadiazoles: synthesis, palladium complexes, and catalysis of Suzuki reactions in aqueous media

A reaction sequence involving transformations of 5-(4-methylphenyl)isoxazole and 4,5-dichloroisothiazole derivatives containing an amidoxime group at position 3 allowed to synthesize the respective 3,5-isoxazolyl(isothiazolyl)-substituted 1,2,4-oxadiazoles. Selective recyclization of 4,5-dichloro-3-(1Н-tetrazol-5-yl)isothiazole and 5-(4-methylphenyl)-3-(1Н-tetrazol-5-yl)isoxazole gave 2,5-isoxazolyl-(isothiazolyl)-substituted 1,3,4-oxadiazoles. The obtained compounds combining three azole heterocycles in one molecule formed palladium complexes that showed high catalytic activity in Suzuki reactions in aqueous and aqueous alcohol media. The bimetallic reusable Pd/Fe catalyst obtained from palladium polyazole complex retained high catalytic activity after five uses.

A Pd(II) complex of a β-cyclodextrin-based polydentate ligand: an efficient catalyst for the Suzuki reaction in aqueous media

Molecular assembly has become a promising strategy for designing new polydentate ligands. But very often such ligands and their complexes are sparingly soluble in aqueous phase due to their intrinsic hydrophobic character. Pd(II) complexes are good homogeneous catalysts but their poor solubility in aqueous phase may limit their catalytic efficacy in the universal green solvent water. However, solubility related challenges especially in aqueous phase can be mitigated through the formation of inclusion complexes by exploiting the hydrophobic nature of the β-cyclodextrin (β-CD) cavity. Hence, an ionic liquid ChCD (1) was synthesized from β-CD and Choline bromide (ChBr). Next a supramolecular N, N′, O-tridentate ligand 1⊂2 (3) was synthesized by the inclusion of 2,6-diaminopyridine (2) in the hydrophobic β-CD cavity of the ionic liquid ChCD (1) and was well characterized by elemental analysis, UV-visible, FTIR, 1H NMR spectroscopy, etc. The stoichiometry of the inclusion complex 1⊂2 (3) was found to be 1:1 based on UV-visible spectrophotometric study. A new air stable, highly water soluble Pd2+-complex [κ3-N, N′, O-Pd(1⊂2)H2O]OAc (4) was then synthesized from the supramolecular ligand (3) with 1:1 stoichiometry and used as a catalyst for Suzuki cross-coupling reactions in water at ambient temperature with good to excellent yields. The catalyst can be removed and recycled. Additionally, the use of non-toxic solvent water makes the methodology green, sustainable, and economically viable.

WITHDRAWN: Multi walled carbon nanotubes modified with mercapto-melamine groups for the stabilization of palladium nanoparticles: An efficient nanocatalyst for the Suzuki reaction in aqueous media under mild conditions

WITHDRAWN: Multi walled carbon nanotubes modified with mercapto-melamine groups for the stabilization of palladium nanoparticles: An efficient nanocatalyst for the Suzuki reaction in aqueous media under mild conditions

WITHDRAWN: Multi walled carbon nanotubes modified with mercapto-melamine groups for the stabilization of palladium nanoparticles: An efficient nanocatalyst for the Suzuki reaction in aqueous media under mild conditions

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Schiff Base-Functionalized Multi Walled Carbon Nano Tubes to Immobilization of Palladium Nanoparticles as Heterogeneous and Recyclable Nanocatalyst for Suzuki Reaction in Aqueous Media Under Mild Conditions

Herein we described the synthesis of a novel Schiff base-MWCNTs-Pd nanocatalyst by covalent grafting of naphto-Schiff base onto carbon nanotubes and subsequent deposition of Pd nanoparticles. The synthetic process of preparation of mentioned nanocatalyst (Schiff base-MWCNTs-Pd) has been described. The formation of nanocatalyst was analyzed by FTIR, Raman spectroscopy, powder XRD, energy dispersive spectroscopy (EDS), thermogravimetric (TGA) analysis, wavelength-dispersive X-ray spectroscopy (WDX) and CHN analysis. The morphologies of the nanocatalyst were characterized using scanning and transmission electron microscopes (SEM and TEM). Additionally, the (Schiff base-MWCNTs-Pd) nanocatalyst was successfully employed in Suzuki cross coupling reactions with wide variety of functionalized substrates. Design of experiments indicates that the use of 0.2 mol% of Pd, K2CO3 as the base, and aqueous ethanol are the best reaction conditions. The reactions of aryl iodides and aryl bromides take place at room temperature, and aryl chlorides react at 80 °C. Interestingly, the novel catalyst could be recovered and recycled four times without any significant loss in activity.

An efficient and recoverable palladium organocatalyst for Suzuki reaction in aqueous media

Meso‐tetrakis[4‐(methoxycarbonyl)phenyl]porphyrinatopalladium(II) as a palladium organocatalyst was synthesized and then used in aqueous media as a heterogeneous organocatalyst in Suzuki reaction. The prepared organocatalyst was characterized using UV–visible, infrared and NMR spectroscopies. It was found to be an efficient catalyst for Suzuki coupling reaction between phenylboronic acid and a broad range of aryl halides. Mild reaction conditions, water solvent as green media, and easy catalyst separation and reusability are the advantages of the presented method.

Functionally substituted isoxazoles and isothiazoles: Synthesis, palladium(II) complexes and their catalytic activity

Functionally substituted 5-(p-tolyl)isoxazoles and 4,5-dichloroisothiazoles, whose molecules contain azomethine, amino, carboxyl, and ester moieties in various combinations in the aromatic ring in the position 3 of heterocycle, were synthesized. Synthesis of complexes of Pd(II) with carboxyl derivative of 1,2-azoles was performed. They show high catalytic activity in the Suzuki reaction in aqueous media.

Pd nanoparticles deposited on Isoniazid grafted multi walled carbon nanotubes: synthesis, characterization and application for Suzuki reaction in aqueous media

The prepared Isoniazide-MWCNTs were used to deposition of Pd NPs as novel nanocatalyst. The catalyst showed high activity in Suzuki coupling reaction of aryl halides (X = I, Br, Cl).

Iron Oxide Nanoparticles Modified with Carbon Quantum Nanodots for the Stabilization of Palladium Nanoparticles: An Efficient Catalyst for the Suzuki Reaction in Aqueous Media under Mild Conditions

AbstractMagnetic Fe3O4 nanoparticles (NPs) functionalized with carbon dots (C‐dots) that contain carboxylic acid and hydroxyl groups were synthesized successfully and used for the reduction of PdII and the formation of Pd NPs. The new material was characterized by SEM, TEM, energy‐dispersive spectroscopy, solid UV spectroscopy, vibrating sample magnetometry, XRD, and X‐ray photoelectron spectroscopy and was used as a very efficient catalyst in the Suzuki–Miyaura cross‐coupling reaction of aryl bromides and chlorides with arylboronic acids in aqueous media. Design of experiments indicates that the use of 0.22 mol % of Pd, K2CO3 as the base, and aqueous ethanol are the best reaction conditions. The reactions of aryl bromides take place at room temperature, and aryl chlorides react at 80 °C. The easily synthesized and air‐stable catalyst Pd@C‐dots@Fe3O4 NPs could be separated from the reaction mixture by using an external magnet and reused in eight consecutive runs with no significant loss of catalytic activity.

Microwave-Assisted Synthesis of Novel Perimidinium Salts as N-Heterocyclic Carbene Precursors: Involvement in Palladium-Catalyzed Cross-Coupling Reactions

In the current study, five novel perimidinium chlorides were synthesized in good yields by reaction of 1-(3-methylbenzyl)perimidine with five different alkyl chlorides under microwave irradiation in 30 minutes. Synthesized compounds were characterized by IR, 1H, 13C NMR spectroscopic methods and elemental analyses. Performance of in situ formed catalytic system which consist of the perimidinium salts and Pd(OAc)2 was investigated for Heck and Suzuki reactions in aqueous media, and desired products were obtained in good yields.

Efficient synthesis of fluoro-containing liquid crystal materials via Pd-catalysed room temperature aerobic Suzuki reactions in aqueous media

A series of fluoro-containing liquid crystal materials were synthesised at room temperature under aerobic conditions in excellent yields starting from fluoro-containing phenylboronic acids with aryl halides in the presence of a simple hydrophilic trans-PdCl2(NH2CH2COOH)2 as catalyst via aqueous media Suzuki cross-coupling reactions. Details relevant to the above reactions and to the reaction sequences adopted to get the corresponding fluoro-containing liquid crystal materials are presented. The structures of above catalyst and liquid crystal materials were characterised by element analyses, electrospray mass spectra, 1H NMR and 13C NMR.

An efficient and simple ligand from phthalandione for palladium-catalyzed Suzuki reaction in aqueous media

An efficient and simple ligand derived from phthalandione was used for palladium catalyzed Suzuki coupling reaction in water/ethanol (V/V=2/1) under aerobic conditions. The reaction exhibited a high catalytic efficiency even with lower Pd loading (0.002mol%). In this work, the catalyst could be successfully used in coupling reaction between various aryl halides with phenylboronic acid in excellent yields with high turnover number (TON) (the maximal TON was up to 49,000 for the reaction of bromobenzene with phenylboronic acid). Moreover, this new ligand had been elucidated by 1H NMR, 13C NMR and X-ray crystal diffraction.

Effective binuclear Pd(II) complexes for Suzuki reactions in water

A series of new ionic binuclear Pd(II) complexes supported by water‐soluble bis(α‐diimine) ligands were prepared and employed as catalysts for the palladium‐catalyzed Suzuki reaction in aqueous media. The binuclear nature of the complexes increased the reaction rate, while electronic and steric modification of the ligand frameworks had a remarkable influence upon the catalytic activity of the palladium complexes. The catalysts were shown to be homogeneous through mercury poisoning experiments and complexes could be recycled more than 10 times without loss of catalytic activity. Copyright © 2013 John Wiley &amp; Sons, Ltd.

An Efficient Microwave-Assisted Suzuki Reaction using a New Pyridine-Pyrazole/Pd(II) Species as Catalyst in Aqueous Media

A new pyridine-pyrazole N–N ligand has been conveniently synthesized and characterized by 1H-, 13C-NMR, IR spectroscopies, HRMS and X-ray single-crystal crystallography analyses. The ligand adds to palladium(II) under basic conditions to give high yields of an air-stable and water-soluble complex that was fully characterized by NMR and HRMS. The complex was investigated as a catalyst for the Suzuki reaction in aqueous media under microwave irradiation. The compound proved to be an effective catalyst.