Catalyst For Heck Coupling Research Articles

Selective hydrogenation catalyst made via heat-processing of biogenic Pd nanoparticles and novel ‘green’ catalyst for Heck coupling using waste sulfidogenic bacteria

A heterogeneous Pd catalyst, biologically-mineralized palladium nanoparticles (bio-Pd), was synthesized using sulfidogenic bacteria which reduced soluble Pd(II) to catalytically-active Pd-nanoparticles (NPs). Heat treatment (processing) of bio-Pd (5 or 20 wt% on the cells) made by Desulfovibrio desulfuricans evolved supported Pd-catalyst comprising Pd-NPs held on large spherical hollow structures. The rate of hydrogenation of 2-butyne-1,4-diol was ~5-fold slower than for a commercial catalyst (~twice that of native bio-Pd), but with high selectivity to the alkene, fulfilling a key industrial criterion. In the Heck reaction, while bio-Pd showed a comparable reaction rate in ethyl cinnamate synthesis to that achieved by commercial Pd/C, heat-treated bio-Pd had negligible activity. D. desulfuricans bio-Pd was replaced by bio-Pd made using a consortium of waste acidophilic sulfidogenic bacteria (CAS) supplied from an unrelated primary remediation process. This gave comparable activity to commercial 5 wt% Pd/C in ethyl cinnamate synthesis, signposting an economic, scalable route to catalyst manufacture.

Palladium nanoparticlesin situsynthesized onCyclea barbatapectin as a heterogeneous catalyst for Heck coupling in water, the reduction of nitrophenols and alkynes

This study develops an effective method forin situsynthesis of PdNPs usingCyclea barbatapectin as green reducing and stabilizing reagent. The catalytic activity of nanocomposite was evaluated for Heck coupling reaction, reduction of nitrophenols and reduction of alkynes.

Alkali/alkaline earth ion-exchanged and palladium dispersed MCM-22 zeolite as a potential catalyst for eugenol isomerization and Heck coupling reactions

Alkali and alkaline earth metal ions (Na+, K+, Cs+, Mg2+) exchanged MCM-22 zeolites were prepared and subsequently palladium (2 wt.%; Pd) was dispersed on above exchanged MCM-22 zeolite materials. All the MCM-22 materials were systematically characterized by FTIR, powder X-ray diffraction, N2 sorption analysis and temperature-programmed desorption (TPD) of CO2. The XRD pattern and FTIR data confirmed the existence of the MCM-22 framework structure even after exchanging bulky metal ions and palladium loading. TPD studies using CO2 supports that the cesium and magnesium incorporated MCM-22 possess a strong and large number of basic sites. The alkali and alkaline-earth metal ions exchanged MCM-22 catalysts were explored for industrially important eugenol isomerisation, whereas the palladium containing MCM-22 materials were utilised for Heck coupling reaction of styrene with iodobenzene. The Cs-MCM-22 showed the best activity for the eugenol isomerization with the isoeugenol yield of 76%. The Cs/Pd-MCM-22 was shown as promising heterogeneous catalyst for Heck coupling reaction of styrene with iodobenzene and yield 99% stilbene. For both isomerization and Heck coupling reaction, the catalysts retain their activities even after several runs. Among different alkali and alkaline earth ion-exchanged MCM-22 materials, cesium containing MCM-22 was shown as a promising catalyst for isomerization of lignin-derived biomass model compound viz., eugenol. Subsequently, the palladium dispersed CsMCM-22 was found to be the potential catalyst for Heck coupling under ambient conditions.

Pd and Ni complexes of a novel vinylidene β‐diketimine ligand: Their application as catalysts in Heck coupling and alkyne trimerization

A β‐diketimine ligand with vinylidene substitution at γ‐carbon, CH2C(CH3CNAr)2 (Ar = 2,6‐diisopropylphenyl) (L2), was synthesized by treating β‐diketimine H2C(CH3CNAr)2 with n‐BuLi followed by paraformaldehyde. L2 formed the homobimetallic ether‐bridged β‐diketiminate complex [O{(CH2‐β‐diketiminate)Pd(OAc)}2] (1) with (PdOAc)2. It also gave complexes [L2PdCl2] (2) and [L2NiBr2] (3) when treated with PdCl2(CH3CN)2 and NiBr2(dimethoxyethane), respectively. All the compounds were characterized using 1H/13C NMR spectroscopy and single‐crystal X‐ray diffraction studies. The catalytic activity of Pd and Ni complexes 1, 2 and 3 was explored in Heck coupling and alkyne trimerization reactions and it was found that they are very good catalysts. The results are reported in detail.

A nitrogen and sulphur functionalized graphene oxide–palladium nanoparticle hybrid catalyst for an efficient Heck coupling

A nanohybrid of Pd on GO functionalized with N and S has been fabricated, and demonstrated as an efficient catalyst for Heck coupling with a substantially low catalytic loading (0.02 mol%).

Palladium complexes containing multidentate phenoxy–pyridyl–amidate ligands: Highly efficient catalyst for Heck coupling of deactivated aryl halides

N,N′,N″,O-Tetrafunctional Pd(II) complexes prepared from the easily available amino acids are shown to be highly efficient catalysts for the Heck reaction of deactivated aryl bromides and iodides with high turnover numbers up to ca.104 and moderate activity for the activation of aryl chlorides under phosphine-free conditions.

New imino-pyridyl nickel(II) complexes: Synthesis, molecular structures and application as Heck coupling catalysts

Reactions of imino-pyridyl ligands, (2-pyridyl-2-thiophenemethyl)imine (L1) and (2-pyridyl-2-thiopheneethyl)imine (L2) with NiBr2(DME) gave the corresponding complexes [Ni(L1)Br2] (1) and [Ni(L2)Br2] (2) in good yields. Treatment of 1 and 2 with one equivalent of 2-hydroxythiophenol resulted in the displacement of the bromide ligands to form the nickel(II) thiolato complexes 3 and 4. Molecular structure of 3 confirmed that L1 and L2 bind to the nickel atom in a bidentate fashion. Complexes 1–4 catalyzed the Heck coupling reaction of iodobenzene and bromobenzene with methyl acrylate.

Bacteria Cellulose Nanofibers Supported Palladium(0) Nanocomposite and Its Catalysis Evaluation in Heck Reaction

Bacteria cellulose (BC) nanofibers supported palladium(0) nanocomposites were prepared and fully characterized in terms of morphology, crystallinity, composition, and thermal stability. The as-prepared catalyst was further successfully explored in Heck coupling reaction between aryl halide and styrene or acrylates, with a yield over 86–96% for the first coupling reaction. With coupling yields decreased less than 10% for the fifth reaction cycle, Pd/BC catalyst exhibits great potential as recyclable catalyst for Heck coupling.

Unconjugated diimine palladium complexes as Heck coupling catalysts

Four unconjugated diimine palladium complexes have been synthesized, and spectroscopically and structurally characterized. All four palladium complexes were used as catalysts in the Heck coupling reaction between iodobenzene and methyl acrylate or butyl acrylate with very good conversion to either methyl (2 E)-3-phenylacrylate or butyl (2 E)-3-phenylacrylate.

Substituted (pyridinyl)benzoazole palladium complexes: Synthesis and application as Heck coupling catalysts

The synthesis of 2-(4- tert-butylpyridin-2-yl)-benzooxazole ( L3), 2-(4- tert-butyl-pyridin-2-yl)-benzothiazole ( L4) and 6- tert-Butyl-2-(4- tert-butyl-pyridin-2-yl)-benzothiazole (L5) by intramolecular cyclization under basic conditions is described. Reactions of 2-pyridin-2-yl-1 H-benzoimidazole ( L1), 2-pyridin-2-yl-benzothiazole ( L2) and L3– L5 with either [Pd(NCMe) 2Cl 2] or [Pd(COD)MeCl] afforded the corresponding mononuclear palladium complexes [Pd( L1)MeCl] ( 1), [Pd( L2)MeCl] ( 2), [Pd( L3)Cl 2] ( 3), [Pd( L3)MeCl] ( 4), [Pd( L4)Cl 2] ( 5), [Pd( L4)MeCl] ( 6) and [Pd( L4)MeCl] ( 7) as confirmed by mass spectrometry and elemental analyses. The palladium complexes are efficient Heck coupling catalysts for the reaction of iodobenzene with butylacrylate under mild conditions. Benzothiazole and benzooxazole containing complexes show faster induction periods compared to the benzoimidazole analogues.

Poly(pyrazol‐1‐ylmethyl)benzene Palladium Complexes: Synthesis, Characterization and Evaluation as Heck Coupling Catalysts.

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Poly(pyrazol-1-ylmethyl)benzene Palladium Complexes: Synthesis, Characterisation and Evaluation as Heck Coupling Catalysts

The poly(pyrazol-1-ylmethyl)benzenes L1 - L5 react with [PdCl2(NCMe)2] or [PdClMe(COD)] to form dinuclear palladium complexes [{PdClX(3,5-Me2pzCH2)2-1,2-C6H4}2] (X = Cl (1), Me (2)), [{PdCl2(3,5-Me2pzCH2)2-1,3-C6H4}2] (3), palladium complexes [{Pd2(μ-Cl)2Me2(3,5- Me2pzCH2)2-1,3-C6H4}] (4), [{Pd2(μ-Cl)2X2(3,5-Me2pzCH2)2-1,4-C6H4}] (X = Cl (5), Me (6)), [{Pd2(μ-Cl)2Cl2(3,5-tBu2pzCH2)2-1,4-C6H4}] (7), and tetranuclear [{Pd2(μ-Cl)2Cl2(3,5- Me2pzCH2)2}2-1,4-C6H4] (8). The structures of 1, 2 and 8 were confirmed by X-ray structure analysis. The complexes efficiently catalyse the coupling reaction of iodobenzene and butylacrylate at 80 °C.

Highly reactive heterogeneous Heck and hydrogenation catalysts constructed through 'bottom-up' nanoparticle self-assembly.

Polymer-mediated self-assembly of functionalized Pd and SiO2 nanoparticles provides highly active hydrogenation and Heck coupling catalysts.

A Pd complex of a tridentate pincer CNC bis-carbene ligand as a robust homogenous Heck catalyst

The bis-carbene precursor, 1, gives a thermally very robust Pd(II) catalyst for Heck coupling that maintains activity even in boiling diethylacetamide (bp 184 °C) in air.