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91.
92.
Regioselectivity of the addition of the highly functionalized zinc-copper reagents to (η3-allyl)Fe(CO)4 cationic salts was studied. For 1,1-disubstituted allyl cation 1, the zinc-copper reagents added predominantly at the unsubstituted terminus. For 1,1,2-trisubstituted allyl cation 2, reactive zinc-copper reagents attacked mainly at the unsubstituted terminus while less reactive zinc-copper reagents added to a coordinated CO ligand. For 1,1,3-trisubstituted allyl cation 3, the addition occurred at both the less substituted allyl terminus and a coordinated CO ligand. 相似文献
93.
Marino Basato Giacomo Facchin Mirto Mozzon Paolo Sgarbossa Augusto Tassan 《Journal of organometallic chemistry》2004,689(2):454-462
2-(Azidomethyl)phenyl isocyanide, 2-(CH2N3)C6H4NC (AziNC), coordinates to some cationic Pt(II) and Pd(II) species to afford isocyanide complexes of the type trans-[MCl(AziNC)(PPh3)2][BF4] (M=Pt, l; Pd, 2). AziNC is coordinated also in some neutral Pt(II) and Pd(II) species such as [MCl2(AziNC)2] (M=Pt, 3; Pd, 4) derived from the reactions of 2 equiv. of AziNC with [PtCl2(COD)] and [PdCl2(MeCN)2], respectively. Complexes 1 and 2 react with 1 equiv. of PPh3 affording the heterocyclic carbene complexes trans-[MCl{(H)}(PPh3)2][BF4] (M=Pt, 5; Pd, 6). Complexes 3 and 4 react with 1 equiv. of PPh3 displacing the isocyanide with the formation of the complexes cis-[MCl2(AziNC)(PPh3)] (M=Pt, 7; Pd, 8). These latter ones react with 2 equiv. of PPh3 affording as the final products the cationic carbene species trans-[MCl{(H)}(PPh3)2][Cl] (M=Pt, 9; Pd, 10). Complex 5 was also characterized by single crystal X-ray diffraction. The carbene complex is square-planar and the angle formed between the platinum square plane and the heterocyclic carbene ligand is 87.9(2)°. The C(1)-N(1) and C(1)-N(2) bond distances in the latter of 1.32(2) and 1.30(2) Å, respectively, are short for a single bond and indicate extensive π-bonding between the nitrogen atoms and the carbene carbon. 相似文献
94.
Flammability, microhardness and transparency of nanocomposites based on functionalized polyethylenes
Y. Peneva 《European Polymer Journal》2006,42(10):2228-2235
The flammability, microhardness and transparency of nanocomposites based on poly(ethylene-co-acrylic acid) copolymers having different concentration of acrylic acid and different molar mass, their Zn ionomer and ethylene-glycidylmethacrylate copolymer as matrixes and on organically modified montmorillonite as a nanofiller have been investigated. The presence and the increase in the content of the clay lead to the increase in the limiting oxygen index and to significant reduction of the burning rate of all materials. The results from the Vickers microhardness measurements have shown that the addition of the clay to matrixes of polar functionalized polyethylenes leads to a significant increase in the microhardness of the materials, while the creep constant does not decrease significantly. The UV spectra show that the light transmittance of the materials does not change significantly in the presence of the clay, i.e., the nanocomposite films preserve the polymer transparency. The results have been interpreted by the intercalated structures of the nanocomposites investigated. 相似文献
95.
Two polysiloxanes with pendant fullerene moieties and their platinum or rhodium complexes havebeen prepared from C_(60) via amination with ω-decenylamine, followed by hydrosilylation with triethoxysilaneand immobilization on fumed silica or by hydrosilylation with methyldichlorosilane and polycondensationwith polydimethylsiloxanol, and then by reacting them with potassium chloroplatinite or rhodium chloride inacetone respectively under argon atmosphere. It was found that the four noble metal complexes are effectivecatalysts for the hydrosilylation of olefins with triethoxysilane. The regioselcctivity of platinum complexesfor styrene increases remarkably by introducing C_(60) moiety. Factors influencing catalytic activity and themechanism have been investigated. 相似文献
96.
Sonochemical synthesis of functionalized multi-walled carbon nanotubes (fMWCNTs) embellished 3D flower-like zinc oxide (ZnO) nanocomposite based novel electrochemical sensor for the detection of toxic environmental pollutant 4-nitrophenol (4-NP) is detailed in this paper. We have used laser-assisted synthesis technique in the development of 3D flower-like ZnO nanoparticles (NPs) and ultrasonication method was employed in preparation of ZnO NPs@fMWCNTs nanocomposite using a high-intensity ultrasonic bath DC200H with power of 200 W/cm2 and 40 KHz frequency. The nanocomposite was meticulously fabricated on screen printed carbon electrode (SPCE) to carry out various electrochemical analysis. Different characterizations such as Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, UV visible spectroscopy (UV–Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) of the materials used in this work were taken. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques are used in electrochemical investigations. We have observed well-defined oxidation and reduction peak currents representing electrochemical mechanism of 4-NP at very low potentials for ZnO NPs@fMWCNTs/SPCE. Furthermore, we were able to achieve efficient electrochemical determination of 4-NP using the developed sensor with a high sensitivity of 11.44 μA μM−1 cm−2 and very low detection limit (LOD) of 0.013 μM in a broad linear range of 0.06–100 μM. All the significant features of a good sensor including anti-interference, good stability, excellent repeatability, and reproducibility were exhibited by the sensor. Moreover, we have tested practical feasibility of sensor by carrying out real sample analysis on different water samples. 相似文献
97.
采用2种有机合成路线制备了结构不同的环糊精共价修饰的功能化石墨烯纳米材料,并利用FTIR,XRD,TEM,SEM和TG分析等技术对产物的结构和性能进行了表征.结果表明,2种石墨烯基纳米材料由于合成策略的不同导致溶剂分散性能存在一定的差别,但它们均可均匀分散于N,N-二甲基甲酰胺(DMF)、二甲基亚砜(DMSO)和乙二醇中.同时,环糊精的引入使其热学稳定性显著提高.该材料在阻燃型复合材料等领域中具有一定的潜在应用价值. 相似文献
98.
Three kinds of molecularly imprinted polymers (MIPs) were obtained with surface molecular imprinting technique on functionalized potassium tetratitanate whisker (F-PTW). The results of adsorption experiments indicated that MIP prepared using PTW modified with N-(2-aminoethyl)-3-(trimethoxysilyl)propylamine (AAPTS) (F-PTW A) as support [MIP(1)] was superior to the other two polymers, then MIP(1) was selected to analyze the 4-nitrophenol (4-NP) adsorption process from aqueous solution in this study. AAPTS offered hydrophilic exterior that allowed to self-assemble with the template 4-NP through intermolecular interaction rather than based on the interactions between the functional monomers and template. Equilibrium adsorption data were analyzed by the Langmuir and Freundlich isotherm models at various temperatures. Kinetic properties were successfully investigated by pseudo-first-order model, pseudo-second-order model, intraparticle diffusion equation, initial adsorption rate, half-adsorption time. A diffusion-controlled process as the essential adsorption rate-controlling step was also proposed. The performance of such imprinted polymer was further demonstrated by high-performance liquid chromatography, and the results showed that the selectivity of MIP(1) exhibited higher affinity for template 4-NP over competitive phenolic compounds than that of non-imprinted polymer NIP(1). MIP(1) could be reused four times without significant loss in the adsorption capacity. 相似文献
99.
Functionalized crosslinked polystyrene-co-divinylbenzene-co-chloromethylstyrene magnetic latex particles were prepared via emulsifier-free miniemulsion polymerization using 2, 2′ azobis (2-amidinopropane) dihydrochloride (V-50) as an initiator and in the presence of magnetite nanoparticles in the monomers. Transmission electron microscopy (TEM) proved the presence of magnetite nanoparticles in polymer particles. Differential scanning calorimetery (DSC) analysis of the product showed an exothermic signal due to crosslinking of chains through electrophilic aromatic substitution of phenyl groups with chloromethyl groups in the presence of the dispersed Fe3O4 as Lewis acid. This was proven by thermogravimetric analysis (TGA) via the loss of gaseous HCl. The results were also compared with those of magnetite-free miniemulsion polymerization using V-50. 相似文献
100.
Five membered carbocycles are important building blocks for many biologically active molecules. Moreover, substituted cyclopentenones (e.g. cyclopentenone prostaglandins) exhibit characteristic biological activity. The efficiency and atom economy of the Pauson-Khand reaction render this process potentially one of the most attractive methods for the synthesis of such compounds. Although it was discovered in its intermolecular form, the scope of the intermolecular Pauson-Khand reaction has always been limited by the poor reactivity and selectivity of the alkene component. The past decade, especially the last three years, has seen concerted efforts to broaden the scope of this reaction. In this overview, we provide a comprehensive and critical coverage of the intermolecular Pauson-Khand reaction based on the reactivity characteristics of different classes of alkenes and a rationalization of successes and misfortunes in this area. 相似文献