Nanoparticles, palladium

Synthesis (TCS). The very same term was independently proporsed by Corain and associates for the size controlled synthesis of palladium nanoparticles in 2004 [68]. In a number of cases they observed that palladium nanoclusters, supported on gel-type resins of different nature and obtained with the RIMP method, exhibited a remarkable agreement between the size of the cavities of swollen supports (as assessed by means of ISEC, see Section 4) and the diameter of the metal nanoclusters (Table 4, Entries 1-3) [10,11,66,71,72,87]. 

Figure 2 schematically presents a synthetic strategy for the preparation of the structured catalyst with ME-derived palladium nanoparticles. After the particles formation in a reverse ME [23], the hydrocarbon is evaporated and methanol is added to dissolve a surfactant and flocculate nanoparticles, which are subsequently isolated by centrifugation. Flocculated nanoparticles are redispersed in water by ultrasound giving macroscopically homogeneous solution. This can be used for the incipient wetness impregnation of the support. By varying a water-to-surfactant ratio in the initial ME, catalysts with size-controlled monodispersed nanoparticles may be obtained. 

The solvent-free controlled thermolysis of metal complexes in the absence or presence of amines is the simple one-pot synthesis of the metal nanoparticles such as gold, silver, platinum, and palladium nanoparticles and Au-Ag, Au-Pt, and Ag-Pd alloy nanoparticles. In spite of no use of solvent, stabilizer, and reducing agent, the nanoparticles produced by this method can be well size regulated. The controlled thermolysis in the presence of amines achieved to produce narrow size dispersed small metal nanoparticles under milder condition. This synthetic method may be highly promising as a facile new route to prepare size-regulated metal nanoparticles. Finally, solvent-free controlled thermolysis is widely applicable to other metal nanoparticles such as copper and nickel... 

Zhou WP, Lewera A, Larsen R, Masel RI, Bagus PS, Wieckowski A. 2006. Size effects in electronic and catalytic properties of unsupported palladium nanoparticles in electrooxidation of formic acid. J Phys Chem B 110 13393-13398. 

A key feature of this study was the structural information available on the model palladium nanoparticle catalyst. The mean particle size is 5.5 nm, containing on average 3000 atoms the majority of the particles are well formed with a (111) orientation and terminated by (111) facets with only a small fraction of (100) facets exposed. 

Okitsu K, Nagaoka S, Tanabe S, Matsumoto H, Mizukoshi Y, Nagata Y (1999) Sonochemical preparation of size-controlled palladium nanoparticles on alumina surface. Chem Lett 28 271-272... 

Okitsu K, Yue A, Tanabe S, Matsumoto H (2000) Sonochemical preparation and catalytic behavior of highly dispersed palladium nanoparticles on alumina. Chem Mater 12 3006-3011... 

Chen W, Cai W, Lei Y, Zhang L (2001) A sonochemical approach to the confined synthesis of palladium nanoparticles in mesoporous silica. Mater Lett 50 53-56... 

Nemamcha A, Rehspringer JL, Kharmi D (2006) Synthesis of palladium nanoparticles by sonochemical reduction of palladium(II) nitrate in aqueous solution. J Phys Chem B 110 ... 

Didgikar MR, Roy D, Gupta SP, Joshi SS, Chaudhari RV (2010) Immobilized palladium nanoparticles catalyzed oxidative carbonylation of amines. Ind Eng Chem Res 49 1027-1032... 

Carbon-Carbon Cross-Coupling Reactions Catalyzed by Palladium Nanoparticles in Ionic Liquids... 

Astruc, D. (2007) Palladium nanoparticles as efficient green homogeneous and heterogeneous carbon-carbon coupling precatalysts a unifying view. Inorganic Chemistry, 46 (6), 1884-1894. 

Nadagouda, M.N. and Varma, R.S. (2008) Green synthesis of silver and palladium nanoparticles at room temperature using coffee and tea extract. Green Chemistry, 10, 859-862. 

Similar Suzuki couplings have been performed by Hu and coworkers utilizing a poly(dicyclohexylcarbodiimide)/palladium nanoparticle composite [152]. This PDHC-Pd catalyst showed remarkable activity and stability under microwave irradiation. Near quantitative conversion (95% isolated yield) was obtained after 40 min of microwave heating of a mixture of iodobenzene with phenylboronic acid in dioxane. Re-using the immobilized catalyzed showed no significant loss of efficiency, as the fifth cycle still furnished a 90% isolated yield of the desired biphenyl. 

Pavlovsky, I., Soundarrajan, P. and Yaniv, Z., Palladium nanoparticle hydrogen sensor, Gases and Technology, 18(July/August), 18, 2006. 

It is considered that the stannyl or silyl radical and the alkyl radical are reactive intermediates in these reactions. In contrast to the selective formation of the arylchalcogenosilanes in the above radical reactions, the cross-coupling reaction of a hydrosilane with alkyl(aryl)sulfides catalyzed by palladium nanoparticles results in the selective formation of the corresponding alkylthiosilanes.42... 

Isoindolones and Related N-Heterocycles via Palladium Nanoparticle-Catalyzed 3-Component Cascade Reactions... 

Liu et al. prepared palladium nanoparticles in water-dispersible poly(acrylic acid) (PAA)-lined channels of diblock copolymer microspheres [47]. The diblock microspheres (mean diameter 0.5 pm) were prepared using an oil-in-water emulsion process. The diblock used was poly(t-butylacrylate)-Wock-poly(2-cinna-moyloxyethyl) methacrylate (PtBA-b-PCEMA). Synthesis of the nanoparticles inside the PAA-lined channels of the microspheres was achieved using hydrazine for the reduction of PdCl2, and the nanoparticle formation was confirmed from TEM analysis and electron diffraction study (Fig. 9.1). The Pd-loaded microspheres catalyzed the hydrogenation of methylacrylate to methyl-propionate. The catalytic reactions were carried out in methanol as solvent under dihydro-... 

Kaifer and coworkers showed interest in the modification of metal nanoparticles with organic monolayers prepared with suitable molecular hosts. They reported the preparation of water-soluble platinum and palladium nanoparticles modified with thiolated /1-cyclodexlrin (/ -CD) [69]. Nanoparticle synthesis was... 

Table 9.4 Phenanthroline-stabilized palladium nanoparticles in PEG for the hydrogenation of alkenes.a) (Adapted from [68])...

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