Poly(di(pyridin‐2‐yl)methyl acrylate) (PDPyMA), which was obtained by the free radical polymerization of designed coordinative monomer of di(pyridin‐2‐yl)methyl acrylate, is able to coordinate with various metal ions to form heterogeneous catalysts for diverse catalytic reactions. The Pd and Cu complexes supported by PDPyMA were developed for the heterogeneous Suzuki‐Miyaura reaction and Friedel‐Crafts alkylation, respectively. The PDPyMA‐based catalysts showed no significant decline of reactivity after five times recycling. However, the hydrolysis of the PDPyMA backbone under alkaline conditions limited the catalytic efficiency of this heterogeneous catalyst so that the coordinative monomer was redesigned as 1,1‐di(pyridine‐2‐yl)‐2‐(4‐vinylphenyl)ethan‐1‐ol and then 2,2′‐(1‐methoxy‐2‐(4‐vinylphenyl)ethane‐1,1‐diyl)dipyridine (MVPhDPy). With copolymerization of N‐isopropyl acrylamide (NIPAM), the efficiency of polymer‐based heterogeneous catalysts could be further raised, demonstrated by the increased turn over number in the Suzuki‐Miyaura reaction, which approached 5,260 by using the catalyst formed from poly(MVPhDPy‐co‐NIPAM) and Pd(OAc)2. poly(MVPhDPy‐co‐NIPAM) copolymer, therefore, could be a versatile platform to support different metal ions for various heterogeneous catalytic reactions. 相似文献
Although water promotes Suzuki–Miyaura coupling reaction, it also induces side reactions such as deboronation and dehalogenation. Therefore, Suzuki–Miyaura polymerization of triolborate halothiophene monomer 1 with tBu3PPd(o‐tolyl)Br ( 2 ) in dry tetrahydrofuran (THF) is investigated. However, the resultant poly(3‐hexylthiophene) (P3HT) shows a broad molecular weight distribution and uncontrolled polymer ends. Model reactions of a number of boron reagents 3 with 2,5‐dibromothiophene ( 4 ) in the presence or absence of water indicate that intramolecular transfer of the catalyst is hardly affected by the boron moiety of 3 , whereas it is hindered in the absence of water. Indeed, polymerization of 1 with 2 in H2O/THF affords P3HT with a narrower molecular weight distribution and controlled tolyl/H ends, as compared to the reaction in dry THF.
A polystyrene‐cross‐linking tricyclohexylphosphine (PS‐TCP) was synthesized through radical emulsion polymerization of 4‐tert‐butylstyrene as a monomer and tris(trans‐4‐styrylcyclohexyl)phosphine as a threefold cross‐linker. The PS‐TCP showed enhanced ligand performance compared to the corresponding polystyrene‐triphenylphosphine hybrid PS‐TPP and tricyclohexylphosphine in Pd‐catalyzed Suzuki–Miyaura and Buchwald–Hartwig reactions of aryl chlorides. 相似文献
A suitable approach to stabilize palladium nanoparticles (Pd NPs), with an average diameter of 3–4 nm, on magnetic polymer is described. A new magnetic polymer containing 4′‐(4‐hydroxyphenyl)‐2,2′:6′,2″‐terpyridine (HPTPy) ligand was prepared by the polymerization of itaconic acid (ITC) as a monomer and trimethylolpropane triacrylate (TMPTA) as a cross‐linker and fully characterized. Pd NPs embedded on the magnetic polymer were successfully applied in Suzuki–Miyaura and Mizoroki–Heck coupling reactions under low palladium loading conditions, and provided the corresponding products with excellent yields (up to 98%) and high catalytic activities (TOF up to 257 hr?1). Also, the catalyst can be easily separated and reused for at least consecutive five times with a small drop in catalytic activity. 相似文献
Herein an efficient bottom‐up solution‐phase synthesis of N=9 armchair graphene nanoribbons (GNRs) is described. Catalyzed by Pd(PtBu3)2, Suzuki–Miyaura polymerization of a simple and readily available triaryl monomer provides a novel GNR precursor with a high molecular weight and excellent solubility. Upon cyclodehydrogenation, the resulting GNR exhibits semiconducting properties with an approximately 1.1 eV band gap (LUMO: ?3.52 eV; HOMO: ?4.66 eV) as characterized by UV/Vis‐NIR spectroscopy and cyclic voltammetry. 相似文献
A simple and effective strategy is described for the synthesis of Pd–CdS nanopowder by the reduction of an organopalladium(II) complex, [PdCl2(cod)] (cod = cis ,cis ‐1,5‐cyclooctadiene), in the presence of CdS quantum dots (QDs) at a toluene–water interface. We investigated the impact of addition of CdS QDs on catalytic activity of Pd nanoparticles (NPs). The Pd–CdS nanopowder functions as an efficient catalyst for Suzuki–Miyaura reactions for the formation of carbon–carbon bonds. There is a high electron density on Pd NPs and due to their high electron affinity they behave as an electron scavenger from CdS increasing the rate of oxidative addition, which is the rate‐determining step of the catalytic cycle, and, just as we expect, the C─C coupling reaction with the Pd–CdS nanopowder is faster and occurs in less time than that with Pd nanocatalysts. Compared to classical reactions, this method consistently has the advantages of short reaction times, high yields in a green solvent, reusability of the catalyst without considerable loss of catalytic activity and low cost, and is a facile method for the preparation of the catalyst. 相似文献
A porphyrin‐based polymer with high surface area was synthesized using 5,10,15,20‐tetraphenylporphyrin through a one‐pot Friedel–Crafts alkylation reaction. Pd(II) was successfully supported on this polymer. This strategy provides an easy approach to produce highly stable Pd–porphyrin‐based polymer. The resulting Pd catalyst was characterized using Fourier transform infrared and X‐ray photoelectron spectroscopies, thermogravimetric analysis, scanning and transmission electron microscopies and N2 adsorption–desorption measurements. This porphyrin‐based polymer‐supported Pd was used as a heterogeneous catalyst for Suzuki–Miyaura coupling reaction in water. The results demonstrated that this Pd catalyst indeed exhibited excellent catalytic activity and recycling performance in water, even for inactive aryl chloride substrate. A new heterogeneous strategy for catalyzing the Suzuki–Miyaura reaction in water is provided. 相似文献
Pyrrolo[2,1‐c][1,4]benzodiazepine‐5,11‐dione and its 7‐bromo derivative were alkylated at the N10 atom applying various methods. The resulting products were subjected to Suzuki–Miyaura reactions using a catalyst system consisting of Pd(Cl)2(PPh3)2 and sodium tert‐butanolate in toluene. Results of an X‐ray single crystal analysis are presented. 相似文献
In this work, an easily obtained procedure was successfully implemented to prepare novel palladium nanoparticles decorated on triethanolammonium chloride ionic liquid‐functionalized TiO2 nanoparticles [TiO2/IL‐Pd]. Different methods were carried out for characterizations of the synthesized nanocatalyst (HR‐TEM, XPS, XRD, FE‐SEM, EDX, FT‐IR and ICP). TiO2/IL‐Pd indicated good catalytic activity for the Suzuki–Miyaura cross‐coupling reaction of arylboronic acid with different aryl halides in aqueous media at ambient temperature. The recycled catalyst was investigated with ICP to amount of Pd leaching after 6 times that had diminished slightly, Thus, was confirmed that the nanocatalyst has a good sustainability for C–C Suzuki–Miyaura coupling reaction. The catalyst can be conveniently separated by filtration of the reaction mixture and reused for 6 times without significant loss of its activity. It supplies an environmentally benign alternative path to the existing protocols for the Suzuki–Miyaura reaction. 相似文献