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1.
An efficient and new protocol for the Heck reaction using palladium nanoparticle‐engineered dibenzo‐18‐crown‐6‐ether/MCM‐41 nanocomposite in water 下载免费PDF全文
Palladium nanoparticle‐incorporated mesoporous organosilica (MCM‐41‐Crown.Pd) was synthesized via the grafting of dibenzo‐18‐crown‐6‐ether moieties on the MCM‐41 surface, followed by reaction of the nanocomposite with palladium acetate and then its reduction in ethanol. The cavity of the immobilized dibenzo‐18‐crown‐6 as host material can stabilize the palladium nanoparticles effectively and prevent their aggregation and separation from the surface. The structure of the nanocomposite was characterized using various techniques. The catalytic properties of the nanocomposite in the Heck coupling reaction, one of the most useful transformations in organic synthesis, between aryl halides and olefins in water were also explored. The main advantages of the method are low cost, high yields, easy work‐up and short reaction time. The nanocatalyst can be easily separated from a reaction mixture and was successfully examined for seven runs, with a slight loss of catalytic activity. 相似文献
2.
Mesoporous Silica MCM‐41 Supported N‐Heterocyclic Carbene‐Pd Complex for Heck and Sonogashira Coupling Reactions 下载免费PDF全文
Heterocyclic carbene‐Pd complex was anchored onto the mesoporous silica MCM‐41 which exhibits high catalytic activity in Heck reaction under phosphine free reaction conditions for the reaction of iodo/bromoarenes with olefinic compounds such as butyl acrylate, isopropyl acrylate and styrene. This catalytic system also showed high activity for Sonogashira coupling reaction of various aryl halides under copper, phosphine and solvent‐free reaction conditions. The air and thermally stable catalyst were reused several times without significant loss of its activity. High efficiency of the catalyst along with its recycling ability and the rather low Pd‐loading demonstrated in both Heck and Sonogashira coupling reactions are the merits of the presented catalyst system. 相似文献
3.
Palladium chloride was grafted to amino‐functionalized MCM‐41 to prepare heterogeneous catalysts. XRD, N2 adsorption–desorption isotherms, IR, 13C and 29Si cross‐polarization magic‐angle spinning NMR spectroscopy and XPS techniques were employed to characterize the catalytic materials. The heterogeneous palladium catalyst exhibited excellent catalytic activity for the Heck vinylation of iodobenzene with methyl acrylate, giving 92% yield of methyl cinnamate in the presence of N‐methylpyrrolidone (NMP) and triethylamine (Et3N). The stability of the heterogeneous catalyst was also studied in detail. The catalytic tests showed that the palladium leaching correlated to solvent, base and palladium loading. The heterogeneous catalyst exhibited excellent stability towards loss of activity and palladium leaching was not observed during six recycles in the presence of toluene and Na2CO3. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
4.
MCM‐41‐supported tridentate nitrogen palladium(II) complex [MCM‐41‐3 N‐Pd(II)] was conveniently synthesized from commercially available and cheap 3‐(2‐aminoethylamino)propyltrimethoxysilane via immobilization on MCM‐41, followed by reacting with pyridine‐2‐carboxaldehyde and PdCl2. It was found that this palladium complex is an excellent catalyst for the Suzuki–Miyaura coupling reaction of aryl bromides on two points: (i) the use of 5 × 10−4 mol equiv. of MCM‐41‐3 N‐Pd(II) under air afforded the coupling products efficiently after easy workup; (2) the catalyst can be reused many times without loss of catalytic activity. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
5.
A new MCM‐41 supported aminopropylsiloxane palladium acetate was prepared and characterized. This catalyst is highly active and stereoselective for Heck reaction at 70°C. 相似文献
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The Stille cross‐coupling reaction of organostannanes with aryl halides was achieved in the presence of a catalytic amount of MCM‐41‐supported mercapto palladium(0) complex (1 mol%) in DMF? H2O (9:1) under air atmosphere in good to high yields. This MCM‐41‐supported palladium catalyst can be reused at least 10 times without any decrease in activity. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
Palladium 2‐mercapto‐N‐propylacetamide complex anchored onto MCM‐41 as efficient and reusable nanocatalyst for Suzuki,Stille and Heck reactions and amination of aryl halides 下载免费PDF全文
Mohsen Nikoorazm Arash Ghorbani‐Choghamarani Nourolah Noori Bahman Tahmasbi 《应用有机金属化学》2016,30(10):843-851
A palladium 2‐mercapto‐N‐propylacetamide complex supported on functionalized MCM‐41 was prepared by a post‐grafting method and considered as an efficient catalyst for C? C cross‐coupling reactions between various aryl halides and sodium tetraphenylborate, phenylboronic acid, triphenyltin chloride or alkenes. Also, this catalyst shows good reactivity towards amination of aryl halides. This nanocatalyst was characterized using thermogravimetric analysis, X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, inductively coupled plasma and transmission electron microscopy techniques. Further results indicated that the heterogeneous catalyst could be recovered easily and reused several times without any loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
9.
Pd(0)‐ S‐propyl‐2‐aminobenzothioate immobilized onto functionalized magnetic nanoporous MCM‐41 as efficient and recyclable nanocatalyst for the Suzuki,Stille and Heck cross coupling reactions 下载免费PDF全文
The present work describes the use of Pd(0)‐ S‐propyl‐2‐aminobenzothioate Complex immobilized onto functionalized magnetic nanoporous MCM‐41(Fe3O4@MCM‐41@Pd‐SPATB) as efficient and recyclable nano‐organometallic catalyst for C–C bond formation between various aryl halides with phenylboronic acid (Suzuki reaction), aryl halides with triphenyltin chloride (Stille reaction), and aryl halides with n‐butyl acrylate (Heck reaction). All the reactions were carried out in PEG‐400 as green solvent with short reaction time and good to excellent yields. This catalyst was characterized by FT‐IR spectroscopy, XRD, TGA, VSM, ICP‐OES, TEM, EDX and SEM techniques. Ease of operation, high efficiency, recovery and reusability for five continuous cycles without significant loss of its catalytic activities or metal leaching are the noteworthy features of the currently employed heterogeneous catalytic system. 相似文献
10.
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. 相似文献
11.
《应用有机金属化学》2017,31(2)
A Pd(II) Schiff base complex as an efficient and highly heterogeneous catalyst was developed by immobilization of a palladium complex on the surface of modified Fe3O4 magnetite nanoparticles. These surface‐modified nanoparticles were characterized using various techniques such as transmission electron microscopy, X‐ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, elemental analysis and Fourier transform infrared spectroscopy. The palladium catalyst exhibited efficient catalytic activity in Suzuki and Heck coupling reactions. This method has notable advantages such as excellent chemoselectivity, mild reaction conditions, short reaction times and excellent yields. The yields of the products were in the range 85–100%. Also, the nanocatalyst can be easily recovered with a permanent magnet and reused at least five times without noticeable leaching or loss of its catalytic activity. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
12.
A palladium–fibroin complex (Pd/Fib.) was prepared by the addition of sonicated fibroin fiber in water to palladium acetate solution. Pd (OAc)2 was absorbed by fibroin and reduced with NaBH4 at room temperature to the Pd(0) nanoparticles. Powder‐X‐ray diffraction, scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, Fourier transform‐infrared, CHN elemental analysis and inductively coupled plasma‐atomic emission spectroscopy were carried out to characterize the Pd/Fib. catalyst. Catalytic activity of this finely dispersed palladium was examined in the Heck coupling reaction. The catalytic coupling of aryl halides (‐Cl, ‐Br, ‐I) and olefins led to the formation of the corresponding coupled products in moderate to high yields under air atmosphere. A variety of substrates, including electron‐rich and electron‐poor aryl halides, were converted smoothly to the targeted products in simple procedure. Heterogeneous supported Pd catalyst can be recycled and reused several times. 相似文献
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The ethylenediamine-functionalized resin-supported Pd(0)complex was prepared from PdCl_2 and ethylenedia-mine-functionalized chloromethylated polystyrene,followed by reduction with KBH_4.The complex was character-ized by FT-IR,XRD,BET,SEM and EDS.The resin-supported catalyst exhibited high catalytic activity in theHeck reaction and could be reused up to 17 times in NMP or 16 times in DMF at 90 ℃ in the Heck reaction of io-dobenzene with acrylic acid.The leaching investigation disclosed that the palladium leaching was caused by the in-teraction of iodobenzene with the metal Pd(0)on supported catalyst.The leached palladium species in filtrate wasvery stable and could be reused five times after the solid catalyst was filtered off.A cross-transfer test in recyclingin the presence of additional carbon disclosed that the soluble leached palladium species had much higher catalyticactivity than supported and/or adsorbed palladium in solid-solution heterogeneous Heck reaction. 相似文献
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Iron‐catalyzed cross‐coupling reaction: Heterogeneous palladium and copper‐free Heck and Sonogashira cross‐coupling reactions catalyzed by a reusable Fe(III) complex 下载免费PDF全文
An interesting silica‐supported iron catalyst was successfully prepared and demonstrated as an efficient heterogeneous catalyst for cross‐coupling reactions of aryl halides. The as‐prepared nanocatalyst was well characterized and found to be highly efficient in Heck reaction under mild and sustainable conditions (water as solvent at 80 °C in short reaction time). Furthermore, the obtained catalyst was used as an efficient, inexpensive and green heterogeneous catalyst for Sonogashira cross‐coupling reactions of various aryl iodides and provided the corresponding products with moderate to good yields. This phosphine, copper and palladium‐free catalyst was simply recovered from the reaction mixture and recycled five times without substantial decrease in its catalytic activity. 相似文献
15.
Mizoroki–Heck and Suzuki–Miyaura reactions mediated by poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐stabilized magnetically separable palladium catalyst 下载免费PDF全文
The purpose of this work was to synthesize and characterize a new magnetic polymer nanosphere‐supported palladium(II) acetate catalyst for reactions requiring harsh conditions. In this regard, an air‐stable, moisture‐stable and highly efficient heterogenized palladium was synthesized by the coordination of palladium(II) acetate with poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid)‐grafted modified magnetic nanoparticles with a core–shell structure. The structure of the newly developed catalyst was characterized using various techniques. The catalytic activity of the resultant nano‐organometallic catalyst was evaluated in Mizoroki–Heck and Suzuki–Miyaura reactions to afford the corresponding coupling products in good to excellent yields. High selectivity as well as outstanding turnover number (14 143, 4900) and turnover frequency (28 296, 7424) values were recorded for the catalyst in Suzuki–Miyaura and Mizoroki–Heck reactions, respectively. Magnetic separation and recycling of the catalyst for at least six runs became possible without any significant loss of efficiency or any detectable palladium leaching. 相似文献
16.
《应用有机金属化学》2017,31(4)
A convenient, mild and cost‐effective synthesis of palladium nanoparticles stabilized by a mixture of natural carbohydrate beads (gum arabic and pectin) as a new bio‐organometallic catalyst is reported. Powder X‐ray diffraction, transmission and scanning electron microscopies and energy‐dispersive X‐ray and UV–visible spectroscopies were employed to characterize this supported Pd nanoparticles/gum arabic/pectin catalyst. The nanocatalyst exhibited efficient activity in Mizoroki–Heck cross‐coupling reactions between various aryl halides and n ‐butyl acrylate under solvent‐free conditions. The catalyst can easily be recovered from the reaction system and reused several times with high yields. The products were obtained in short reaction times with excellent yields. 相似文献
17.
A novel palladium catalyst immobilized on polyacrylonitrile fiber mats (Pd/PAN) was prepared by electrospinning. The catalytic activity and recyclability of the microwave‐assisted Pd/PAN fiber mats were examined for the Mizoroki–Heck cross‐coupling of aryl iodides with three different acrylates in aqueous solution. The morphology of the prepared Pd/PAN fiber mats was characterized by scanning electron microscopy. The large size of the PAN fiber mat‐supported palladium catalyst enables much easier separation from the reaction mixture by simple filtration. Density functional theory calculation indicates that the chelation energy of palladium chloride (PdCl2) with propionitrile (model of PAN) is considerable smaller than that of PdCl2 with water, suggesting that the stability and reactivity of the Pd/PAN fiber mats catalyst could be improved through the surface derivatization with polar functional groups. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
18.
An improved and eco‐friendly procedure has been developed to generate mesoporous silica‐supported palladium nanoparticles (SiO2@PdNP) that could be used as a sustainable heterogeneous Pd catalyst for phosphine‐free Suzuki–Miyaura and Heck coupling reactions with excellent turnover number and turnover frequency. The presence of Pd on the silica surface was detected by X‐ray diffraction and the structural morphology of SiO2@PdNP was obtained by transmission electron microscopy. The heterogeneous catalytic system is recyclable and leaching of the metal after the reaction is not apparently observed. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
19.
《应用有机金属化学》2017,31(2)
Palladium nanoparticles supported on activated carbon were prepared by argon glow discharge plasma reduction (Pd/C‐P) without any chemical reducing agents and protective agents. The as‐prepared Pd/C‐P catalyst was characterized using nitrogen adsorption–desorption, X‐ray diffraction and transmission electron microscopy analyses. The results showed that the palladium nanoparticles reduced by plasma are well dispersed with a smaller particle size than commercial Pd/C. Pd/C‐P exhibited a high catalytic activity in Suzuki and Heck coupling reactions. Moreover, there was no obvious loss of catalytic activity even after eight repeated cycles, showing good reactivity and recyclability. 相似文献