Palladium particles from oxime-derived palladacycle supported on Fe3O4/oleic acid as a catalyst forthe copper-free Sonogashira cross-coupling reaction

An oxime-derived palladacycle was synthesized using4-bromobenzoxime and pyridine in CHCl3, and characterized by FT-IR and1H NMR spectroscopy. This Pd complex was supported on Fe3O4/oleic acid and shown to be an efficient catalyst for the copper-free Sonogashira cross-coupling reaction of various aryl halides with phenylacetylene in air and in ethanol or mixed aqueous medium. The oxime-derived palladacycle gave highly active palladium nanoparticles for the organicsynthesis. The coupling products were obtained in high yields with low Pd loading and theheterogeneous catalyst can be separated by an external magnet andreused six times without loss of its activity. The characterization of the catalyst wascarried out by XRD, SEM and TEM. Both TEM and XRD revealed that the palladium nanoparticles were well dispersed with diameters from 5 to 10 nm and average size 9.97 nm.     

An Efficient and Practical Process for Pd/Cu Cocatalyzed Homocoupling Reaction of Terminal Alkynes Using Sodium Percarbonate as a Dual Reagent in Aqueous Media

A new process for the Pd/Cu co-catalyzed homocoupling reaction of terminal alkynes was developed. The reaction was carried out in aqueous media with sodium percarbonate as both a clean oxidant and a base. Meanwhile, a palladium complex immobilized on a synthetic PS-PEG400-PPh2 resin was used as the catalyst, which may be recovered by simple filtration and reused for several times with high activity.     

Chitosan-immobilized Palladium Complex：a Green and Highly Active Heterogeneous Catalyst for Heck Reaction

A green heterogeneous catalyst for Heck reaction-chitosan-immobilized palladium complex was prepared.The catalyst exhibits high activity and stereoselectivity under the moderate reaction conditions.The catalyst can be separated easily from the reaction mixture and reused after washing.Under the suitable reaction conditions,the cross-coupling of iodobenzene (ArI) with acrylic acid (AA) or acrylate can be achieved 93.3% or 99% yield of trans-cinnarnic acid or trans-cinnamic ester.     

Preparation and application of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide

A new method for the preparation of SBA-15-supported palladium catalyst for Heck reaction in supercritical carbon dioxide was presented.The newly formed SBA-15-supported palladium catalyst（Ph-SBA-15-PPh₃-Pd） exhibited high catalytic activity for the Heck reaction of 4-nitrobromobenzene with methyl acrylate.The catalyst can be reused several times without a loss of activity.     

Suzuki Reaction of Aryl Bromides Using a Phosphine-Free Magnetic Nanoparticle-Supported Palladium Catalyst

A palladium catalyst immobilized on superparaganetic nanoparticles was prepared with a palladium loading of 0.30 mmol/g. The catalyst was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, thermogravimetric analysis, Fourier transform infrared, atomic absorption spectrophotometry, and nitrogen adsorption. The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl bromides with phenylboronic acid. The recovery of catalyst was simply by magnetic decantation in the presence of a magnet. The immobilized palladium catalyst can be reused many times without significant degradation in catalytic activity. No leaching of active palladium species into the reaction solution was detected.     

三(羟甲基)氨基甲烷改性SiO_2固载钯纳米粒子:合成、表征及其催化Heck偶联反应活性（英文）

The preparation of supported Pd nanoparticles on Tris(tris(hydroxymethyl)aminomethane)‐ modi‐fied Si O2 gel and their catalytic application in Heck coupling are investigated. The catalyst was char‐acterized using a combination of X‐ray diffraction, transmission electron microscopy, field‐emission scanning electron microscopy, and scanning electron microscopy/energy‐dispersive X‐ray spec‐troscopy. The supported Pd nanoparticles were found to be a highly active and reusable catalyst for the Heck reaction at a low Pd loading(0.02 mol%) because of stabilization by the Tris moieties. Several reaction parameters, including the type and amount of solvent, base, and temperature, were evaluated. The heterogeneity of the catalytic system was investigated using different approaches, and showed that slight Pd leaching into the reaction solution occurred under the reaction condi‐tions. Despite this metal leaching, the catalyst can be reused seven times without significant loss of its activity.     

Complete Oxidation of Methane over Palladium Supported on Alumina Modified with Calcium,Lanthanum,and Cerium Ions

The activity and thermal stability of Pd/Al_2O_3 and Pd/(Al_2O_3 MO_x)(M=Ca,La,Ce) palladium catalysts in the reaction of complete oxidation of methane are presented in this study.The catalyst supports were prepared by sol-gel method and they were dried either conventionally or with supercritical carbon dioxide.Then they were impregnated with palladium nitrate solution.The catalysts with unmodified alumina had a high surface area.The activity and thermal stability of the alumina- supported catalyst was also very high.The introduction of calcium,lanthanum,or cerium oxide into alumina support caused a decrease of the surface area in the way dependent on the support precursor drying method.These modifiers decreased the activity of palladium catalysts,and they required higher temperatures for the complete oxidation of methane than unmodified Pd/Al_2O_3.The improvement of the palladium activity by lanthanum and cerium support modifier was observed only at low temperatures of the reaction.     

An efficient catalytic system for the synthesis of glycerol carbonate by oxidative carbonylation of glycerol

Glycerol carbonate was synthesized by the oxidative carbonylation of glycerol catalyzed by the commercial Pd/C with the aid of NaI.High conversion of glycerol(82.2%),selectivity to glycerol carbonate(>99%),and TOF(900 h–1)were obtained under the conditions of 5 MPa(pCO:pO2=2:1),140 oC,2 h.The highly active palladium species were generated in situ by dissolution from the carbon support and stabilized by re-deposition onto the support surface after the reaction was finished.Palladium dissolution and re-deposition were crucial and inherent parts of the catalytic cycle,which involved heterogeneous reactions.This Pd/C catalyst could be recycled and efficiently reused for four times with a gradual decrease in activity.Moreover,the influences of various parameters,e.g.,types of catalysts,solvents,additives,reaction temperature,pressure,and time on the conversion of glycerol were investigated.A reaction mechanism was proposed for oxidative carbonylation of glycerol to glycerol carbonate.     

Porous polymer supported palladium catalyst for cross coupling reactions with high activity and recyclability

Porous polymer supported palladium catalyst for cross coupling reactions with high activity has been successfully prepared by coordination of Pd 2+ species with Schiff bases functionalized porous polymer. The catalyst has been systemically investi-gated by a series of characterizations such as TEM, N 2 adsorption, NMR, IR, XPS, etc. TEM and N 2 isotherms show that the sample maintains the nanoporous structure after the modification and coordination. XPS results show that chemical state of palladium species in the catalyst is mainly +2. More importantly, the catalyst shows very high activities and excellent recycla-bility in a series of coupling reactions including Suzuki, Sonogashira, and Heck reactions. Hot filtration and poison of catalysts experiments have also been performed and the results indicate that soluble active species (mainly Pd(0) species) in-situ gener-ated from the catalyst under the reaction conditions are the active intermediates, which would redeposit to the supporter after the reactions.     

Macroporous magnetic poly(GMA-EGDMA-DVB) microspheres supported palladium complex as an efficient catalyst for Heck reaction

<正>Macroporous magnetic poly(GMA-EGDMA-DVB) microspheres synthesized by suspension polymerization were used as supports for palladium catalyst.The results showed the novel magnetic catalyst can promote Heck reaction of aryl halides with acrylic acid efficiently without an inert atmosphere.In addition,the novel catalyst can be conveniently recovered by applying an external magnet and reused at least five times without significant loss of its activity.     

胺基化树脂负载Pd(0)对Heck反应催化性能的研究

将氯球用胺化剂、乙二胺、胍进行胺化后负载氯化钯, 在乙醇溶液中用硼氢化钾还原, 制备了含胺功能基树脂负载钯(0)的催化剂; 研究了催化剂对含各种取代基碘代苯与丙烯酸的Heck芳基化反应催化性能. 结果表明, 该类催化剂具有良好的催化活性和重复使用性能, 其中用乙二胺功能化树脂负载的Pd(0)催化剂在90 ℃重复使用17次时能保持良好的催化活性. 催化剂反应前后的SEM形貌图和过滤液的活性试验表明催化剂活性组分Pd(0)在反应中有沥取(leaching)现象.     

Guanidine‐Functionalized Resin‐Supported Pd(0) Catalyst: Activity,Reusability, and Redeposition of Active Pd Species in Heck Vinylation

The guanidine‐functionalized resin‐supported Pd(0) catalyst [GDR·Pd(0)] is highly active in Heck reaction of aryl bromides with acrylic acid or styrene without the need to exclude air. The catalyst can be recycled at least 9 times without significant loss of activity in N‐methyl‐2‐pyrrolidone at 140 °C. The Heck reaction proceeds homogeneously with dissolved palladium species and the dissolved active palladium species can redeposit onto the surface of catalyst in the reaction. The XRD peak shifting of Pd phases in the catalyst provides the evidence for the re‐deposition of the active palladium species.     

Synthesis of chitosan derivatives supported palladium complexes and their catalytic behavior in the Heck reaction

Two kinds of chitosan derivatives, crosslinked chitosan and crosslinked chitosan condense with salilylaldehyde, supported palladium complexes (CL‐CTS‐Pd and CL‐S‐CTS‐Pd) were synthesized and characterized by X‐ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential thermal analysis (DTA), etc. These complexes are efficient catalysts for the Heck reaction under atmospheric conditions and can be easily recovered and reused. The detailed studies show that the catalyst CL‐S‐CTS‐Pd is much more efficient than CL‐CTS‐Pd under the same conditions. CL‐S‐CTS‐Pd keeps its catalytic activity in the Heck reaction of acrylic acid with iodobenzene even at a low temperature (60°C) or with tiny amounts of the catalyst (0.05 mol%Pd). Yields of making cinnamic acid were even as high as 75.3% in the Heck reaction of acrylic acid with iodobenzene using CL‐S‐CTS‐Pd that was recovered 10 times. Copyright © 2005 John Wiley & Sons, Ltd.     

Palladium nanoparticles supported on poly (N-vinylpyrrolidone)-grafted silica as new recyclable catalyst for Heck cross-coupling reactions

Novel catalytic system based on palladium nanoparticles supported on poly (N-vinylpyrrolidone) (PVP) grafted silica was prepared. Aminopropylsilica was reacted with acryloyl chloride to form acrylamidopropylsilica, and onto this functionalized silica vinylpyrrolidone monomer was polymerized by free-radical polymerization. The complexation of PVP-grafted silica with PdCl₂ was carried out to obtain the heterogeneous catalytic system. X-ray diffraction (XRD) technique and transmission electron microscopy (TEM) image showed that palladium dispersed through the support in nanometer size. This catalytic system exhibited excellent activity in cross-coupling reactions of aryl iodides, bromides and also chlorides with olefinic compounds in Heck-Mizoraki reactions in short reaction time and high yields. Elemental analysis of Pd by inductively coupled plasma (ICP) technique and hot filtration test showed low leaching of the metal into solution from the supported catalyst. The catalyst can be reused several times in repeating Heck reaction cycles without considerable loss in its activity.     

Palladium supported on diaminoglyoxime‐functionalized Fe3O4 nanoparticles as a magnetically separable nanocatalyst in Heck coupling reaction

A hybrid material of palladium supported on diaminoglyoxime‐functionalized Fe₃O₄ was used as an effective and recyclable catalyst in Mizoroki–Heck coupling reactions. The catalyst was very effective for the Mizoroki–Heck reaction of aryl halides with styrene and conversion was in most cases excellent. The yields of the products were in the range 75–98%. The catalyst showed good stability and could be recovered and reused for six reaction cycles without significant leaching and loss its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Silica–acetylacetone‐supported palladium nanoparticles as an efficient and reusable catalyst in the Heck–Mizoroki C–C cross‐coupling reaction

The preparation of palladium nanoparticles supported on acetylacetone‐modified silica gel and their catalytic application for Heck olefination of aryl halides were investigated. The catalyst was characterized using X‐ray diffraction, X‐ray photoelectron spectroscopy, and transmission and scanning electron microscopies. The supported palladium nanoparticles are demonstrated to be a highly active and reusable catalyst for the Heck reaction. Several reaction parameters, including type and amount of solvent and base, were evaluated. The heterogeneity of the catalytic system was investigated with results indicating that there is a slight palladium leaching into the reaction solution under the applied reaction conditions. Despite this metal leaching, the catalyst can be reused nine times without significant loss of catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.     

高活性氨基胍树脂负载Pd(0)配合物的催化性能研究

以氨基碳酸胍改性氯球为载体, 与氯化钯溶液反应并还原制备氨基胍树脂负载钯(0)催化剂. 对催化剂进行了FT-IR, XRD, BET, TG-DTA表征. 研究了该催化剂对各种取代卤代苯与丙烯酸、苯乙烯的Heck芳基化反应催化性能. 实验结果表明, 该催化剂对活性(吸电子基)溴代苯和碘苯具有良好的催化活性, 对含活性吸电子基的溴代苯(4-溴苯甲醛和4-溴硝基苯)于140 ℃时能在22 min内完成Heck 芳基化反应; 催化剂具有较好的重复使用性能, 在90 ℃下催化碘苯与丙烯酸的反应循环21次时仍能保持良好的催化活性. 反应机理研究表明: 催化反应的活性组分是可溶性钯物种; 可溶性钯是由卤代苯与催化剂表面上的钯氧化加成所致.     

炭负载Pd/Ce双金属催化剂对Heck反应的催化性能

通过简便的方法制备了炭负载Pd/Ce双金属催化剂,利用Pd/Ce双金属催化剂的协同效应提高催化剂对Heck反应的催化效率。 以碘苯与丙烯酸的Heck芳基化反应为模型反应,研究了反应条件对催化剂催化性能的影响。 结果显示,在反应温度为130 ℃,反应时间为5 h,N,N-二甲基甲酰胺(DMF)作为溶剂和三丁胺(Bu₃N)作为碱的条件下,炭负载Pd/Ce双金属催化剂对丙烯酸和碘苯的Heck芳基化反应具有良好的催化性能,产率达到70%以上。 另外,该催化剂属于非均相催化剂,催化剂易与反应溶液分离;也可以重复利用,使用3次反应产率仍达到66.9%,显示了炭负载Pd/Ce双金属催化剂良好的催化活性。     

Investigation of Pd leaching from supported Pd catalysts during the Heck reaction

Palladium supported on amorphous silica, mercapto-functionalized silica, amine functionalized silica, and zeolite Y has been studied as a catalyst in the Heck reaction of iodobenzene with butyl acrylate in the presence of triethylamine base and dimethylformamide solvent. Trapping of soluble Pd with poly(4-vinylpyridine), hot filtration tests during the batchwise Heck reaction, and reaction tests of effluents from a fixed bed continuous reactor support the conclusion that leached Pd is the active phase in the Heck reaction for all of the catalysts tested. Two different paths of Pd leaching that depend on the chemical state of the Pd were elucidated in this study. Oxidative addition of aryl halide to reduced Pd caused leaching of samples containing metallic particles. However, for a zeolite Y sample containing unreduced cationic Pd, the presence of triethylamine base was required to leach Pd into solution. These two paths of Pd leaching are consistent with the generally accepted mechanism of the Heck reaction.     

Synthesis of polyphenol microsphere‐supported palladium complex and evaluation of its catalytic performance for Heck reaction

Polyphenol microspheres were prepared by template polymerization of phenol in the presence of horseradish peroxidase as bio‐enzyme catalyst and aqueous 1,4‐dioxane as solvent. The morphology of polyphenol microspheres thus obtained was observed with a scanning electron microscope. Further, polyphenol microspheres as obtained were loaded with palladium to generate polyphenol microsphere‐supported Pd complex. Resultant Pd complex catalyst supported by polyphenol microspheres was characterized by means of Fourier transformation infrared spectrometry, X‐ray diffraction, X‐ray photoelectron spectroscopy and scanning electron microscopy, and its thermal stability was examined. Moreover, the catalytic activity of polyphenol microsphere‐supported Pd catalyst as synthesized for the Heck reactions of acrylic acid with aryl iodides was evaluated. Results indicate that the polyphenol microsphere as obtained has a diameter of about 500 nm. Polyphenol microsphere‐supported Pd catalyst, as synthesized, at a dosage of 0.37 mol% Pd, possesses good catalytic activity for the Heck reactions of acrylic acid with aryl iodides in air at a low temperature of 50°C, and it also exhibits catalytic activity for bromide and activated chlorobenzene. The polyphenol microsphere‐supported Pd complex has good thermal stability, and it can be readily separated and reused; the yield of the reaction of iodobenzene with acrylic acid remains at 82% after five recycle runs, showing promising potential as a catalyst for Heck reactions. Copyright © 2012 John Wiley & Sons, Ltd.