Catalyst For Suzuki-Miyaura Cross-coupling Reaction Research Articles

Palladium immobilized on the surface of MMT K 10 with the aid of [BMIM][BF4]: An efficient catalyst for Suzuki-Miyaura cross-coupling reactions

The designing of a new heterogeneous catalyst for palladium catalyzed Suzuki-Miyaura cross-coupling reactions at room temperature is of great interest from green chemistry perspectives. In this work, neutral ionic liquid [BMIM][BF4] was used as an anchor for immobilizing palladium on the surface of MMT K 10. The procedure for the synthesis of the catalyst is quite simple and the entire process is conducted under room temperature. The catalyst formed consists of palladium nanoparticles which were characterized by TEM, SEM and XRD. The new heterogeneous catalyst showed excellent catalytic activity toward biaryl synthesis in water at room temperature.

팔라듐 담지 다공성 폴리우레아를 불균일 촉매로 활용한 Suzuki-Miyaura 커플링 반응

다공성 고분자(porous organic polymer, POPs)는 높은 표면적을 가지는 무정형의 고분자이다. 본 연구에서는 우레아 축합반응으로 UPOP라는 다공성 고분자를 합성하였다. UPOP는 Brunauer-Emmett-Teller(BET) 분석을 통해 다공성을 확인하였고, 불균일 촉매 활용성을 보기 위하여 팔라듐을 담지하여 Pd@UPOP를 합성하였다. Pd@UPOP는 XPS 분석을 통해 Pd 담지를 확인하였고, Suzuki-Miyaura 커플링 반응을 이용하여 촉매활성을 측정하였다. Pd@UPOP의 촉매활성은 물과 ethanol이 3:1이고 K₂CO₃를 사용하였을 때 가장 높았다. 특히 이 조건에서 Pd@UPOP를 촉매로 사용하여 공기 중에서 반응시켰을 때 Pd 함량은 0.1 mol%였음에도 불구하고 99% 이상의 수율을 보였다. 또한 5번 재사용하였을 때도 90%의 수율을 유지하였다.

Palladium-scavenging self-assembled hybrid hydrogels - reusable highly-active green catalysts for Suzuki-Miyaura cross-coupling reactions.

A hybrid hydrogel based on 1,3:2,4-dibenzylidene sorbitol (DBS) modified with acyl hydrazides combined with agarose was used for in situ reduction and binding of palladium from aqueous mixtures without the need for an external reducing agent. Palladium uptake was monitored and the formation of Pd nanoparticles (PdNPs) trapped within the gel and located close to the nanofibres was confirmed. This gel effectively scavenges palladium from solution to concentrations < 0.04 ppm - well below the recommended limits for pharmaceutical products. The resulting hybrid hydrogel with embedded PdNPs was used as a catalyst for Suzuki-Miyaura cross-coupling reactions. The gel network stabilises PdNPs, preventing aggregation/leaching and giving excellent catalytic lifetimes. The gel acts as a simple reaction dosing form, being simply added to reactions performed in green solvents in air. Once reactions are complete, the gel can be simply removed, recycled and reused (>10 times). Reactions were purified by simple washing protocols, and leaching of Pd from the gels is limited (<1 ppm). The gels were also used in flow-through mode, giving efficient, rapid reactions, with easy work-up. These catalytic gels combine advantages of homogeneous and heterogeneous catalysts - they are solvent compatible with the reaction taking place in a solution-like environment, while the solid-like gel network enables catalyst recycling. In summary, these hydrogels scavenge 'waste' palladium and convert it into gel 'wealth' capable of efficient, environmentally-friendly Suzuki-Miyaura catalysis.

Design and syntheses of a new family of palladium complexes derived from tridentate ligands and their application as catalysts for Suzuki-Miyaura cross-coupling reactions

Palladium complexes [Pd(L1−5)(PPh3)]ClO4 (LnH (n = 1–5, H = phenolic dissociable proton) (1–5)) were synthesised and characterised by different spectroscopic methods like 1H NMR, IR and UV-visible spectral studies. The molecular structure of the representative complex [Pd(L2)(PPh3)]ClO4 (2) was determined by X-ray crystallography. These new complexes were utilised to study Suzuki-Miyaura cross-coupling reactions. Substituted aryl halides were reacted with the phenylboronic acid in presence of these palladium-based catalysts and sodium hydroxide. Biphenyl and its derivatives were synthesised via. C-C bond formation. The plausible mechanism of these cross-coupling reactions was proposed on the basis of theoretical calculation utilising density functional theory (DFT).

Post-synthetic modification of IRMOF-3 with an iminopalladacycle complex and its application as an effective heterogeneous catalyst in Suzuki-Miyaura cross-coupling reaction in H2O/EtOH media at room temperature

A novel iminopalladacycle complex was successfully immobilized onto a metal–organic framework (MOF) through post-synthetic modification of IRMOF-3. Initially, the IRMOF-3 was modified with benzaldehyde to achieve a Schiff-base moiety in the pores of IRMOF-3 (IRMOF-3-BI) which could anchor the palladium by the addition of palladium acetate (IRMOF-3-BI-Pd). The catalyst was fully characterized by using a variety of methods such as attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), energy dispersive X-ray (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). Also, the structural unities of MOFs have been confirmed by scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. Moreover, the prepared catalyst has shown excellent turnover frequencies as a heterogonous catalyst in the Suzuki C-C coupling reaction for aryl iodides, bromides and chlorides in H2O/EtOH media at room temperature. Additionally, the catalyst can be easily isolated from the reaction mixture and recycled for five sequential runs without incredible decrease in catalytic efficiency.

Immobilization of palladium nanoparticles on ionic liquid-triethylammonium chloride functionalized magnetic nanoparticles: As a magnetically separable, stable and recyclable catalyst for Suzuki-Miyaura cross-coupling reactions

A facile procedure was applied to successfully synthesize novel Pd nanoparticles immobilized on triethanolamine-functionalized magnetic nanoparticles [Fe3O4/IL/Pd]. Diverse characterizations (HR-TEM, XRD, FT-IR, TGA, EDX, FE-SEM, ICP, XPS and VSM) were carried out to identify intrinsic traits of the nanoparticles. At room temperature, Fe3O4/IL/Pd demonstrated high catalytic activity toward Suzuki-Miyaura cross-coupling reactions in aqueous solution. Based on the results, Fe3O4/IL/Pd acted as zwitterionic IL-type heterogeneous catalyst, which could be separated from the reaction mixture, conveniently. Moreover, it exhibited excellent recyclability for at least eight cycles without considerable loss of its activity.

An immobilized symmetrical bis-(NHC) palladium complex as a highly efficient and recyclable Suzuki-Miyaura catalyst in aerobic aqueous media.

A bis-N-heterocyclic carbene (NHC) functionalized with chloropropyltriethoxysilane over silica was used to synthesize a well-defined immobilized palladium complex. This complex is a suitable and easily retrievable catalyst for Suzuki-Miyaura cross-coupling reactions under mild aqueous conditions. Excellent yields and conversions were obtained with low palladium loadings (down to 0.03 mol% Pd). The catalyst can be reused up to six cycles without the loss of its activity. The catalytic role of the NHC complex of palladium during coupling between bromobenzene and phenylboronic acid was investigated theoretically. The oxidative addition step is predicted to be endothermic in agreement with the experimental conditions.

Solid-state Synthesis of Polyhedral Oligomeric Silsesquioxane-Supported N-Heterocyclic Carbenes/Imidazolium salts on Palladium Nanoparticles: Highly Active and Recyclable Catalyst

We describe a novel and green synthetic methodology for the fabrication of polyhedral oligomeric silsesquioxane-supported N-heterocyclic carbenes/imidazolium salts on palladium(II) complexes; Pd(II)-MPIm-POSS (1) composite by solid-state annealing between Pd(OAc)2 and octakis(3-(1-methylimidazolium)propyl) octasilsesquioxane without added base. Subsequently, arylboronic acid based in situ or ex situ reduction of 1 in aqueous ethanol produces polyhedral oligomeric silsesquioxane-supported N-heterocyclic carbenes/imidazolium salts on palladium nanoparticles; Pd(0)-nano-POSS (2) composite, consisting of monodispersed and N-heterocyclic carbene (NHC) stabilized Pd nanoparticles of very small size (3.0 ± 1.5 nm). Nanocatalyst 2 is a highly efficient and easily recyclable homogeneous catalyst for Suzuki-Miyaura cross-coupling reactions with TOF up to 1670 h−1.

Lanthanide Metal-Organic Frameworks with Six-Coordinated Ln(III) Ions and Free Functional Organic Sites for Adsorptions and Extensive Catalytic Activities

Three chelating-amino-functionalized lanthanide metal-organic frameworks, Y-DDQ, Dy-DDQ and Eu-DDQ, were synthesized with a flexible dicarboxylate ligand based on quinoxaline (H2DDQ = N, N′-dibenzoic acid-2,3-diaminoquinoxaline). The three-dimensional framework is constructed by the H2DDQ linkers connecting the zigzag ladders, showing a net of sra topology. In the structures, one kind of Ln(III) ions metal centers are six-coordinated and thus can potentially behave as open metal sites (OMSs), while the free chelating amino groups can act as free functional organic sites (FOSs). The N2 and Ar adsorption behaviors indicate that these Ln-DDQ exhibits stable microporous frameworks with high surface area after remove of the solvents. Owing to presence of OMSs and FOSs, these MOFs show good ability of CO2, dyes captures and Lewis acid catalyst for cyanosilylation reaction. In view of the existing FOSs in the framework, Pd NPs were immobilized onto the MOFs through graft interactions between free chelating amino groups and metal ions precursor using postsynthetic modification. The well dispersed Pd@Ln-DDQs exhibit efficient and recyclable catalytic reduction of 4-nitrophenol to 4-aminophenol, and they can also act as an excellent catalyst for Suzuki-Miyaura cross-coupling reactions with the exposed Pd NPs.

The continuous synthesis and application of graphene supported palladium nanoparticles: a highly effective catalyst for Suzuki-Miyaura cross-coupling reactions

AbstractAn efficient, sustainable, and continuous method for the preparation of graphene supported palladium nanoparticles (Pd/G) has been developed using microwave irradiation as a heating source for the metal deposition process. The Pd/G produced from this method was effective in Suzuki-Miyaura cross-coupling reactions with a broad range of substrates. When incorporated into a packed bed flow reactor, this ligand free catalyst system continued to demonstrate high reaction conversions with limited catalyst leaching in the reaction mixture (347 ppb palladium).

PdCl2Immobilized in Polyacrylamide: a Low Cost and Eco-Friendly Catalyst for Suzuki-Miyaura Reactions

PdCl2 immobilized in polyacrylamide (PAM), named Pd/PAM, produced at an extremely low cost, was found to be an efficient catalyst for Suzuki-Miyaura cross-coupling reactions. Iodo- and bromoarenes may couple with phenylboronic acid under eco-friendly conditions (i.e., phosphine-free and with ethanol as the solvent) to give excellent product yields. Aryl chlorides, in contrast, were found to be unsuitable reagents in this context, yielding modest results. The recyclability of Pd/PAM is limited because of PdII leaching, which leaves only the base polymer on the surface after six runs. The Pd/PAM catalyst was initially prepared via the formation of a PAM hydrogel using an aqueous PdCl2 solution. After drying, the solid Pd/PAM was characterized by scanning electron microscopy (SEM), electron-dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma optical emission spectrometry (ICP OES).

ChemInform Abstract: Catalytic Palladium Nanoparticles Supported on Nanoscale MOFs: A Highly Active Catalyst for Suzuki—Miyaura Cross‐Coupling Reaction.

Abstract Pd nanoparticles have been successfully supported on nanoscale metal-organic frameworks (NMOFs) by using a simple and effective microwave-assisted impregnation process. The resulting composite, representing as a highly active NMOFs supported metal nanoparticles catalyst for the Suzuki cross-coupling reaction between aryl/heteroaryl halides and arylboronic acids, is well characterized, and its high activity and good recyclability are discussed in details. It reveals that, compared to the corresponding bulk MOFs and conventional active carbon materials, nanoscale MOFs as novel support materials for heterogeneous catalysts can exhibit superior performance in the catalytic reactions.

Ni/Pd core/shell nanoparticles supported on graphene as a highly active and reusable catalyst for Suzuki-Miyaura cross-coupling reaction

Monodisperse Ni/Pd core/shell nanoparticles (NPs) have been synthesized by sequential reduction of nickel(II) acetate and palladium(II) bromide in oleylamine (OAm) and trioctylphosphine (TOP). The Ni/Pd NPs have a narrow size distribution with a mean particle size of 10 nm and a standard deviation of 5% with respect to the particle diameter. Mechanistic studies showed that the presence of TOP was essential to control the reductive decomposition of Ni-TOP and Pd-TOP, and the formation of Ni/Pd core/shell NPs. Using the current synthetic protocol, the composition of the Ni/Pd within the core/shell structure can be readily tuned by simply controlling the initial molar ratio of the Ni and Pd salts. The as-synthesized Ni/Pd core/shell NPs were supported on graphene (G) and used as catalyst in Suzuki-Miyaura cross-coupling reactions. Among three different kinds of Ni/Pd NPs tested, the Ni/Pd (Ni/Pd = 3/2) NPs were found to be the most active catalyst for the Suzuki-Miyaura cross-coupling of arylboronic acids with aryl iodides, bromides and even chlorides in a dimethylformamide/water mixture by using K2CO3 as a base at 110 °C. The G-Ni/Pd was also stable and reusable, providing 98% conversion after the 5th catalytic run without showing any noticeable Ni/Pd composition change. The G-Ni/Pd structure reported in this paper combines both the efficiency of a homogeneous catalyst and the durability of a heterogeneous catalyst, and is promising catalyst candidate for various Pd-based catalytic applications. Open image in new window

Silica-supported palladium complex: An efficient, highly selective and reusable organic–inorganic hybrid catalyst for the synthesis of E-stilbenes

A novel, highly efficient and reusable palladium based catalyst has been synthesized by covalent grafting of diphenyldiketone–monothiosemicarbazone on silica gel followed by metallation with palladium chloride, and the resulting organic–inorganic hybrid material was found to be highly effective catalyst for Suzuki-Miyaura cross-coupling reaction of various aryl halides with alkenyl boronic acid to give stilbenes. The catalyst was characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray fluorescence (ED-XRF), BET surface area analysis, solid-state 13C CPMAS NMR spectroscopy, atomic absorption spectroscopy (AAS), scanning electron microscopy (SEM) and elemental analysis. High turnover frequency, mild reaction conditions, high selectivity for E-stilbenes, and easy recovery and reusability of the catalyst renders the present protocol highly indispensable to address the industrial prerequisites and environmental concerns.

Controlled immobilization of palladium nanoparticles in two different fluorinated polymeric aggregate cores and their application in catalysis

Fluoroalkyl end-capped betaine-type cooligomeric nanocomposites-immobilized palladium nanoparticles were prepared by the reactions of palladium chloride with sodium acetate in the presence of sodium chloride and the corresponding fluorinated cooligomers. Outer blocks of poly(2,3,4,5,6-pentafluorostyrene)-containing ABA-triblock copolymeric nanocomposites-immobilized palladium nanoparticles were prepared by the use of the corresponding block copolymers under similar conditions. TEM images showed that palladium nanoparticles can be immobilized outside the fluorinated cooligomeric nanocomposite cores; in contrast, palladium nanoparticles can be effectively immobilized inside these fluorinated ABA-triblock copolymeric nanocomposite cores. Thus, these two different fluorinated copolymers enabled the controlled immobilization of palladium nanoparticles in the fluorinated nanocomposite cores. These fluorinated nanocomposites-immobilized palladium nanoparticles were also applied to the catalysts for Suzuki-Miyaura cross-coupling reaction, and the different reactivity between these nanocomposites was observed.

Recyclable Catalysts for Suzuki-Miyaura Cross-Coupling Reactions at Ambient Temperature Based on a Simple Merrifield Resin Supported Phenanthroline-Palladium(II) Complex

A novel Merrifield resin immobilized phenanthroline-palladium(II) complex has been developed and was found to be an efficient catalyst for Suzuki-Miyaura cross-coupling reaction between arylboronic acids and a range of aryl halides under mild reaction conditions. The catalyst exhibited both high catalytic activity and stability for Suzuki-Miyaura reaction. Furthermore, the catalyst could be recycled at least 10 times without a significant loss of catalytic activity.

Facile Synthesis of Highly Stable Gold Nanoparticles and Their Unexpected Excellent Catalytic Activity for Suzuki−Miyaura Cross-Coupling Reaction in Water

We have demonstrated that poly(2-aminothiophenol)-stablized gold nanoparticles with proper gold size and polymer thickness are active catalysts for Suzuki-Miyaura cross-coupling reaction of aryl halides with arylboronic acids in water and air for the first time. High yields can be obtained with aryl halides or arylboronic acids bearing a variety of substituents. This new finding will undoubtedly broaden the application of gold nanoparticles in organic catalytic reactions.

Sterically controlled formation of monodentate versus chelating carbene ligands from phenylhydrazine

Palladium-templated addition of phenylhydrazine to methylisocyanide led to a Chugaev-type chelating dicarbene–palladium complex that is an effective catalyst for Suzuki-Miyaura cross-coupling reactions of aryl bromides and activated aryl chlorides. In contrast, the use of isopropylisocyanide resulted in an unprecedented complex containing aminohydrazinocarbene ligands, which was characterized by X-ray crystallography. The latter complex represents a possible intermediate in the formation of chelating carbene ligands.