石墨烯负载钯催化碘苯与丙烯酸的Heck反应

采用Hummers法合成了氧化石墨烯,通过化学还原制备得到石墨烯负载钯催化剂(Pd/Gr)。对催化剂进行了傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、透射电镜(TEM)等表征,评价了催化剂在碘苯与丙烯酸的Heck偶联反应中的性能。结果表明,Pd粒子均匀分布在石墨烯载体上,其平均粒径约为6.5 nm;Pd/Gr催化剂对Heck反应具备较高的催化活性,当催化剂用量为10 mg,碱用量为30 mmol时,在130℃下反应5 h,肉桂酸收率可达70%。     

石墨烯负载钯催化碘苯与丙烯酸的Heck反应

采用Hummers法合成了氧化石墨烯,通过化学还原制备得到石墨烯负载钯催化剂(Pd/Gr)。对催化剂进行了傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、透射电镜(TEM)等表征,评价了催化剂在碘苯与丙烯酸的Heck偶联反应中的性能。结果表明,Pd粒子均匀分布在石墨烯载体上,其平均粒径约为6.5 nm;Pd/Gr催化剂对Heck反应具备较高的催化活性,当催化剂用量为10 mg,碱用量为30 mmol时,在130℃下反应5 h,肉桂酸收率可达70%。     

交联腐植酸负载钯催化剂对Heck反应催化性能研究

通过简单的方法制得了环氧氯丙烷交联腐植酸负载钯配合物催化剂,并通过IR、TG进行表征。该催化剂能够成功地催化芳基卤和不同取代芳基卤与丙烯酸、苯乙烯和丙烯酰胺的Heck反应。进一步研究显示:环氧氯丙烷交联腐植酸负载钯催化剂还能够催化溴苯与丙烯酸、苯乙烯和丙烯酰胺的反应,产率都达到95%以上;在62℃及催化剂钯含量为0.038%的条件下也能很好地催化碘苯与丙烯酸的反应。催化剂经过简单的分离处理重复使用7次仍然可以得到75.6%的产率。     

聚苯乙烯负载二环己胺钯催化Heck反应的研究

以聚苯乙烯树脂为载体、二环己胺为配体制备聚苯乙烯负载胺钯催化剂。采用XPS、XRD、TG、DTA和SEM等方法对其进行表征,针对不同催化体系探讨丙烯酸、苯乙烯与芳基碘的Heck反应的催化性能。结果表明,高分子胺配体与钯之间形成配位作用,制备的催化剂在室温～200 ℃有较好的热稳定性。该负载型催化剂在N₂氛围只需少量的催化剂就能较好地催化丙烯酸、苯乙烯与芳基碘的Heck反应,较高收率地生成取代的反式肉桂酸和1,2-二苯基乙烯。     

Ethylenediamine-functionalized activated carbon anchored palladium complex: a recyclable catalyst for Heck reaction

Ethylenediamine-functionalized activated carbon anchored palladium catalyst was prepared via grafting ethylenediamine onto chemically modified activated carbon, followed by the reaction with palladium chloride and then the reduction with potassium borohydride. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy results indicated that palladium immobilized on the carrier via coordination bond in this catalyst. Transmission electron microscopy images showed that the supported palladium is in the form of near spherical particles smaller than 10 nm diameter and evenly dispersed on the surface of the carrier. This catalyst was applied for the Heck reaction of aryl halides with olefins. The influences of solvents, bases, reaction temperatures and times on catalytic property of the catalyst were investigated by using the coupling of iodobenzene and styrene as a probe reaction. By varying the combination of aryl halides and olefins, this catalyst showed effective catalytic activities to produce corresponding coupling products with moderate to excellent yields. Moreover, it can be recovered by simple filtration and reused several times without significant loss of activity and selectivity.     

Palladium(II) containing hydrotalcite as an efficient heterogeneous catalyst for Heck reaction

Palladium(II) containing hydrotalcite (Pd-HT) has been found to be an efficient and reusable catalyst in Heck reaction between aryl halides (X = Br, I) and olefins to give carbon–carbon coupled products in good to moderate yields.     

Catalytic performance of cellulose supported palladium complex for Heck reaction in water

Cellulose supported palladium complex was synthesized and characterized by XPS, TG/DTA etc. The complex was found to be an efficient catalyst for Heck reaction of acrylic acid or styrene with aryl iodides at low temperature in water under atmospheric condition, the substituted trans‐cinnamic acid or 1,2‐stilbene was obtained in stereoselectivity. Repeated tests showed that the catalyst have good reusability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

芳胺化PVDC负载钯化合物在微波促进下催化Suzuki偶联反应

聚偏二氯乙烯(PVDC)被二苯胺(DPA)修饰后可以有效负载氯化钯,从而制得催化剂PVDC-DPA-Pd。利用TG,DTA,IR等测试手段对其表征。热分析表明,催化剂在室温至150℃有很好的热稳定性。该催化剂在微波促进条件下在较短时间内就可以有效地催化芳基溴化合物(甚至活化的芳基氯化物)与四苯硼钠间的Suzuki偶联反应,并且在较短的时间(10 min)或较少的催化剂用量(0.01%)下,仍有很好的产率。并且催化剂回收再利用3次后,产率仍能达到75%。     

A novel SiO2 supported Pd metal catalyst for the Heck reaction

A ligand-free heterogeneous metal catalyst system (represented as Pd/SiO₂ (O)) derived by calcination of Pd(acac)₂/SiO₂ in air and its catalytic properties toward the Heck coupling of bromobenzene (PhBr) and styrene have been studied. X-ray photoelectron spectroscopy (XPS) and catalytic results demonstrate that most of Pd²⁺ is reduced to Pd⁰ on SiO₂ by N,N-dimethylacetamide (DMA) during the Heck reaction and that the resulting Pd⁰/SiO₂ is highly active for the Heck reaction, the remaining Pd²⁺/SiO₂ is not responsible for the high activity. Pd/SiO₂ (O) possesses incomparable advantages over a heterogeneous homolog (represented as Pd/SiO₂ (H)) prepared by reduction of Pd(acac)₂/SiO₂ in H₂ as a pre-catalyst in both activity and catalyst recycling. The activity over Pd/SiO₂ (O) is comparable to that over a homogeneous Pd system. Transmission electron microscopy (TEM) analysis illustrates that the high activity over Pd/SiO₂ (O) consists in the small size of supported Pd particles generated in-situ with gentle reducing agents at a mild temperature.     

Modified polyacrylonitrile fiber as a renewable heterogeneous base catalyst for Henry reaction and Gewald reaction in water

A polyacrylonitrile fiber catalyst with high polar surface micro‐environment (C‐PANF‐Na) was conveniently synthesized and characterized by elemental analysis, Fourier‐transfer infrared spectroscopy, UV–vis spectroscopy, scanning electron microscopy, X‐ray diffraction, and breaking strength test. The catalytic performance of the fiber was tested by Henry reaction and Gewald reaction in water and favorable results were obtained in terms of high yields, mild conditions, extensive applicability, superior catalytic recyclability, and renewability. It also has advantages of easy preparation, high functional degree, good stability in acid and base, high strength, and good flexibility, and so on. In addition, a high solvent selectivity phenomenon was found in this catalytic system and the reason was explained by proposing a high polar micro‐environment effect. Furthermore, the fiber catalyst performed well in scaled‐up experiment and flow chemistry experiment, which shows tremendous potential in industrial catalyst as an ideal material for packed bed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45992.     

Carbon nanofiber-supported palladium nanoparticles as potential recyclable catalysts for the Heck reaction

5 wt% Pd catalysts supported on platelet carbon nanofibers has been prepared by incipient wetness impregnation. Both the calcination and the reduction temperature have a significant effect on the dispersion of palladium and it was found that about 3 nm sized Pd nanoparticles can be obtained at a calcination and reduction temperature of 250 °C and 150 °C, respectively. Pd catalysts have been applied to catalyze Heck reactions of various activated and non-activated aryl substrates. The activity increased exponentially with a decrease in Pd particle size. The high surface area, mesoporous structure of carbon nanofiber and highly dispersed palladium species on carbon nanofibers makes up one of the most active and reusable heterogeneous catalysts for Heck coupling reactions. Pd nanoparticles supported on platelet CNFs appear to be an excellent catalyst due to high activity, low sensitivity towards oxygen, almost no or low issues with leaching and high stability in multi-cycles.     

Synthesis of chitosan microsphere-resin supported palladium complex and its catalytic properties for Mizoroki–Heck reaction

Chitosan microsphere-resin supported palladium complex was synthesized and characterized by SEM/EDS, FT-IR, TG/DTA and XPS. The configuration of microsphere with a diameter of 10–100 μm was exhibited through SEM images. The microsphere-resin possesses a high thermal stability as proved by the TG/DTA. Some investigations were later carried out on the catalytic properties of the complex for Mizoroki–Heck reaction. It was found that the complex could not only efficiently catalyze Mizoroki–Heck reaction of iodobenzene with acrylic acid, but it also exhibited catalytic properties for the activated bromobenzene. Surprisingly, the complex was an efficient catalyst in inorganic base and water system, especially, a moderate yield of 76% was obtained by using water as solvent.     

Catalytic performance of PVC‐triethylene‐tetramine supported palladium complex for Heck reaction

Polyvinyl chloride‐triethylene‐tetramine supported palladium complex (PVC‐TETA‐Pd) was prepared from polyvinyl chloride via simple method and the production cost of the complex was remarkably low. The complex was an efficient catalyst for Heck reaction. It was active for low activity substrates such as aryl bromides and aryl chlorides. The coupling of bromobeneze with styrene catalyzed by PVC‐TETA‐Pd afforded 99.8% yield of stilbene under the optimized reaction conditions. PVC‐TETA‐Pd could catalyze the Heck reactions in the presence of several different kinds of acid‐binding agents. Furthermore, the good reusability of PVC‐DTA‐Pd was also found for Heck reaction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Homogeneous/heterogeneous palladium based catalytic system for Heck reaction. The reversible transfer of palladium between solution and support

Pd(II)/Al₂O₃ and Pd(0)/Al₂O₃, containing 0.6% of palladium were characterized by EDX, SEM and XRD methods and used as catalysts of the Heck coupling of bromobenzene with butyl acrylate at 140 °C in molten [Bu₄N]Br salt. Monoarylated (trans-PhCH = CHC(O)OBu) (1) and diarylated (Ph₂C = CHC(O)OBu) (2) products were obtained in amounts dependent on kind of base present in the system (Scheme 1). During the reaction palladium was partially leached from the support forming [Bu₄N][PdBr₄] complex that catalyze Heck reaction or undergo readsorption on Al₂O₃. These soluble palladium complexes are partially reduced to Pd soluble nanoparticles which can also be anchored on Al₂O₃ giving active catalyst of Pd(0)/Al₂O₃ type. Reduction of Pd(II) to Pd(0) during catalytic process at the presence of bases (NaHCO₂, NaHCO₃, NaOAc, Cs₂CO₃) was studied by XPS method and the total reduction was observed in reactions of PdCl₂(PhCN)₂ with NaHCO₂ or with NaHCO₃ and [Bu₄N]Br. It was experimentally proved that heterogenized catalyst, Pd(0)/Al₂O₃, after oxidative addition of aryl halides, serve as a source of soluble palladium species and colloidal nanoparticles that are active as homogeneous catalysts.     

Synthesis of cenosphere supported heterogeneous catalyst and its performance in esterification reaction

A heterogeneous catalyst has been developed from cenosphere, a byproduct generated in thermal power plant. The performance of catalyst was investigated in the esterification of propionic acid and ethanol. The catalyst was characterized by FTIR, X-ray diffraction, field emission scanning electron microscope, and Brunauer–Emmett–Teller surface area and surface acidity analysis. The response surface methodology (RSM) with the Box–Behnken design was employed to design the experiments as well as to optimize the various process parameters such as catalyst loading, alcohol/acid molar ratio, and reaction temperature. The characterization revealed that the cenosphere supported catalyst possessed increased amounts of silica content, surface hydroxyl groups, surface area as well as surface acidity as compared with that of pristine cenosphere. The catalyst showed an excellent activity in the esterification reaction with a maximum conversion up to 91%. The RSM model well fitted the experimental data and predicted optimal conditions which were validated experimentally with a good agreement. The recyclability study showed a significant catalytic stability up to three reaction cycles. This study reveals that the cenosphere supported catalyst can be used as a potential catalyst in the esterification reaction may replace the conventional homogeneous acid catalyst.     

Heck reaction using nickel/TPPTS catalyst and inorganic base on supported ethylene glycol phase

The vinylation of butyl acrylate and halobenzene was studied using the Ni/TPPTS (TPPTS: triphenylphosphine trisulfonate, sodium salt) catalyst immobilized on silica. Inorganic base such as potassium acetate was found to be effective. The catalyst stability and recycle ability have been studied in the temperature range of 130–150°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

非均相催化剂二氧化硅负载高氯酸在有机合成中的应用

二氧化硅负载高氯酸(HClO4/SiO2)作为非均相催化剂被广泛应用于各种有机反应中。主要综述了HClO4/SiO2催化Mannich反应、Friedlnder反应、Hosomi-Sakurai反应、Hantzsch反应以及α-氨基膦酸酯、β-烯胺酮(酯)和高烯丙基胺的合成等。同时对其今后的发展与应用前景进行了展望。     

Palladium nanoparticles embedded chitosan/poly(vinyl alcohol) composite nanofibers as an efficient and stable heterogeneous catalyst for Heck reaction

In this study, palladium nanoparticles were successfully embedded into modified chitosan/poly(vinyl alcohol) composite nanofibers (Pd-CS/PVA nanofibers) by electrospinning. Then, the Pd-CS/PVA nanofibers were treated at evaluated temperature to improve its solvent resistance and in situ reduce Pd²⁺ cations into Pd⁰ active species. The incorporated palladium nanoparticles with ultra small mean diameter of 3.73 ± 1.04 nm are evenly distributed inside the Pd-CS/PVA nanofiber. The resulting Pd-CS/PVA nanofiber mat exhibits high catalytic activity for Heck reaction of aromatic iodides with alkenes and can be recycled for 18 times without loss of initial activity. The high catalytic activity and stability of Pd-CS/PVA nanofiber mat can be attributed to the ultra small diameter nanofibers, strong chelating ability of chitosan, and fine embedment of palladium species inside the nanofiber. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48026.