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101.
Summary The grafting of minerals by alkenylchlorosilanes leads to organomineral derivatives which are superficially covered by unsaturated organic groups. These groups may be of value when the grafted mineral is used as a reinforcing agent in a polymeric matrix. In this case, the unsaturated grafted groups copolymerize with an organic monomer to build up a composite material. It is therefore of importance to preserve the unsaturated character of the alkenyl-silane during the grafting reactions. It is shown that in certain synthesis conditions, the hydrochloric acid present in the reaction medium adds to the alkenyl-groups. For instance, in the grafting of methylvinyl-dichlorosilane, this reaction is of minor importance, whereas in the case of allyldimethylchlorosilane, no allyl groups are grafted as such on the mineral surface.
With 2 figures
Part 1: Nature and role of the hydrolysis products of the methylvinyldichlorosilane in the grafting of silicates in hydrochloric acid and isopropanolThis journal 256, 135 (1978). 相似文献
Zusammenfassung Die Pfropfung von silicatischen Mineralen mit Alkenylchlorosilanen führt zu organischen Derivaten, deren Oberfläche mit ungesättigten organischen Gruppen bedeckt ist. Diese Gruppen können Vorteile bieten, wenn die so behandelten Minerale als Fül-stoffe oder Verstärker in einer Polymermatrix eingesetzt werden. Die ungesättigten Gruppen können miteinem organischen Monomer kopolymerisieren und ein echtes Verbundmaterial bilden. Die Pfropfung muß allerdings so geführt werden, daß der ungesättigte Charakter der Alkenylsilane erhalten bleibt. In der Arbeit werden experimentelle Bedingungen dafür berichtet.
With 2 figures
Part 1: Nature and role of the hydrolysis products of the methylvinyldichlorosilane in the grafting of silicates in hydrochloric acid and isopropanolThis journal 256, 135 (1978). 相似文献
102.
Bustamante JJ Garcia M Gonzalez L Garcia J Flores R Aguilar RM Trevino A Benavides L Martinez AO Haro LS 《Electrophoresis》2005,26(23):4389-4395
A method for separating proteins with a molecular mass difference of 2 kDa using SDS-PAGE under nonreducing conditions is presented. A sample mixture containing several human growth hormone (hGH) isoforms was initially separated on a weak anion-exchange column. Fractions rich in 24 kDa hGH as determined by analytical SDS-PAGE were pooled and further separated by cation-exchange chromatography. The fractions pooled from the cation-exchange chromatography contained two hGH isoforms with a 2 kDa molecular mass difference according to SDS-PAGE analysis, 22 and 24 kDa hGH. The 22 and 24 kDa hGH were separated using continuous-elution preparative double-inverted gradient PAGE (PDG-PAGE) under nonreducing conditions. The preparative electrophoresis gel was composed of three stacked tubular polyacrylamide matrices, a 4% stacking gel, a 13-18% linear gradient gel, and a 15-10% linear inverted gradient gel. Fractions containing purified 24 kDa hGH were pooled and Western blot analysis displayed immunoreactivity to antihGH antibodies. PDG-PAGE provides researchers with an electrophoretic technique to preparatively purify proteins under nonreducing conditions with molecular mass differences of 2 kDa. 相似文献
103.
Three different reaction procedures for the coordination of N-n-butyl-N'-(2-pyridylmethyl)imidazolium salt have produced new N-heterocyclic complexes of Rh and Ir. The direct reaction of the imidazolium salt with [IrCl(cod)](2) provides a NHC-Ir(III)-H complex, while transmetalation from a silver-NHC complex and deprotonation with NEt(3) give new NHC complexes of M(I) and M(III) when reacting with [MCl(cod)](2) or [MCl(coe)(2)](2) (M = Rh, Ir). The crystal structures of the biscarbene Rh(III) and Ir(III) complexes are described. The catalytic properties of the compounds obtained have been tested in the hydrosilylation of acetylenes, the cyclization of acetylenic carboxylic acids, and hydrogen transfer to ketones. 相似文献
104.
M. A. Aramendia V. Boráu C. Jimenez J. M. Marinas 《Reaction Kinetics and Catalysis Letters》1981,18(3-4):335-339
The synthesis and physicochemical properties of new metallic systems obtained by supporting Pd on colloidal AlPO4, AlPO4–SiO2 and AlPO4--Al2O3 to be used as reduction catalysts are reported. The catalytic activity of the above systems in the transfer reduction of nitrobenzene using cyclohexene as hydrogen donor has been measured.
, Pd AlPO4, AlPO4SiO2 AlPO4-Al2O3 . , .相似文献
105.
The conventional four-step sequential extraction method and the EDTA and acetic acid single extraction procedures were applied to sewage sludge and sediment samples. The results obtained with these samples for Cu, Cr, Ni, Pb and Zn using the Tessier method were compared with those supplied by the two single extraction procedures employed. In addition, the Tessier method was also applied to a reference material, CRM 483, and these results were also compared with the certified EDTA and acetic acid values for this sample. As a result, good agreement was found between the metal contents released in the first three fractions of the Tessier method and those leached by the simpler single extraction procedures for the most of the elements studied. Subsequently, the conventional EDTA and acetic acid extraction methods were accelerated by means of microwave energy, in order to reduce the operating time. The extraction efficiency of the first three fractions of the Tessier method was compared with that obtained using the optimised microwave single extraction procedures and only in sewage sludge and CRM 483 samples were satisfactory results found for all the elements studied, except Cr and Pb. This means that the microwave single extraction procedures optimised in this work could be employed as screening methods to evaluate rapidly the easiest mobilizable heavy metals in these samples, although more samples should be analysed to determine their general applicability. The application of the accelerated single extraction procedures to a reference material, CRM 483, provided satisfactory results for all the elements studied, except for Cr in both methods and for Pb in the acetic acid extracts. 相似文献
106.
Maria Ana Castro Zulema D. Chaia Oscar E. Piro Fabio D. Cukiernik Eduardo E. Castellano Marcia Rusjan 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(7):m393-m395
The title compound, tetrakis(μ‐3,4,5‐triethoxybenzoato‐κ2O:O′)bis[(pyrazine‐κN)rhodium(II)](Rh—Rh), [Rh2(C13H17O5)4(C4H4N2)2], crystallizes on an inversion centre in the triclinic space group . The equatorial carboxylate ligands bridge the two RhII atoms, giving a binuclear lantern‐like structure. The pyrazine molecules occupy the two axial coordination sites. The phenyl rings are tilted by ca 10° with respect to the attached carboxylate groups. The pyrazine planes have a torsion angle of ca 19° around the Rh—N bond with respect to the plane of the nearer carboxylate group and are not coplanar with the Rh—Rh bond. 相似文献
107.
Barluenga J Ballesteros A Bernardo De La Rúa R Santamaría J Rubio E Tomás M 《Journal of the American Chemical Society》2003,125(7):1834-1842
Cyclization reactions of group 6 Fischer carbene complexes with cyclopentanone and cyclohexanone enamines are described. Enamine 3a undergoes thermal alpha,beta,beta'-annulation with alkenylcarbene complexes 1 and 2 (THF, 60 degrees C), affording semibullvalenes 5. The metalate intermediates 6, resulting from beta,beta'-annulation of the enamines 3a and 4a, were quantitatively formed by running the reaction in hexane at room temperature. Acid-promoted demetalation of 6 afforded endo-2-bicyclo[3.2.1]octen-8-ones 7 and endo/exo-2-bicyclo[3.3.1]nonen-9-ones 8 (endo/exo = 5:1). Using (S)-methoxymethylpyrrolidine-derived enamines 3b and 4b,c allowed highly enantioenriched cycloadducts endo-(+)-7 as well as endo-(-)-8 and exo-(-)-8 to be accessed. The non-heteroatom-stabilized carbene complex 10 was formed from complex 6 by Me(3)SiOTf-promoted elimination of the methoxy group, characterized by (13)C NMR, and transformed into the organic compounds 7, 7-d, and 11 as well as into bicyclo[3.2.1]octan-2,8-diones 14 and cycloheptanones 15. On the basis of this sequence, enantioenriched cycloheptanones (+)-15 were efficiently prepared in one pot from carbene complexes 2 and enamine 3b (51-55% yield, 91-96% ee). Extension of this work to simple Fischer carbene complexes 16 allowed an appropriate way to generate the nonstabilized pentacarbonyl[(phenyl(alkyl)carbene]tungsten complex 17 to be designed, for which the thermal and chemical behavior leading to compounds 18-21 is described. 相似文献
108.
Cornejo A Fraile JM García JI García-Verdugo E Gil MJ Legarreta G Luis SV Martínez-Merino V Mayoral JA 《Organic letters》2002,4(22):3927-3930
[formula: see text] A chiral pyridine-bis(oxazoline) ligand, functionalized with a vinyl group in the pyridine ring, can be polymerized with styrene and divinylbenzene to obtain supported chiral ligands. As proof of the usefulness of this supported ligands, the corresponding ruthenium complexes are catalysts for the cyclopropanation reaction of styrene with ethyl diazoacetate with up to 85% ee. 相似文献
109.
María L. Dell'Arciprete Carlos J. Cobos Dr. Jorge P. Furlong Dr. Daniel O. Mártire Dr. Mónica C. Gonzalez Dr. 《Chemphyschem》2007,8(17):2498-2505
The kinetics of the oxidation of pyridine, 3‐chloropyridine, 3‐cyanopyridine, 3‐methoxypyridine and 3‐methylpyridine mediated by SO4 < M ‐> radicals are studied by flash photolysis of peroxodisulphate, S2O82?, at pH 2.5 and 9. The absolute rate constants for the reactions of both, the basic and acid forms of the pyridines, are determined and discussed in terms of the Hammett correlation. The monosubstituted pyridines react about 10 times faster with sulphate radicals than their protonated forms, the pyridine ions. The organic intermediates are identified as the corresponding hydroxypyridine radical adducts and their absorption spectra compared with those estimated employing the time‐dependent density functional theory with explicit account for bulk solvent effects. A reaction mechanism which accounts for the observed intermediates and the pyridinols formed as products is proposed. 相似文献
110.
Eduardo Prez-Cordero Rosanna Buigas Nancy Brady Luis Echegoyen Claudia Arana Jean-Marie Lehn 《Helvetica chimica acta》1994,77(5):1222-1228
Reductive electrocrystallization at a constant current density (11.0–11.5 μA/cm2) of millimolar solutions of [M(bpy)3](PF6)2, where M = Fe, Ru, or Os, and bpy = 2,2′-bipyridine in acetonitrile containing 0.1M Bu4NPF6 results in the formation of dark crystals on the Pt cathode. The crystals grow as long, thin, and shiny needles having a hexagonal cross section of 0.1–0.5 mm in diameter. Combustion microanalyses results are consistent with the composition for [Fe(bpy)3], [Ru(bpy)3], and [Os(bpy)3]. In addition, the chromophores are conserved, as confirmed by recording both the electronic and the 1H-NMR spectra after reoxidation of the electrocrystals in humid air. The spectra are identical to those for authentic samples of [Fe(bpy)3]2+, [Ru(bpy)3]2+, and [Os(bpy)3]2+. A ratio of 2.0 ± 0.1 e?/molecule is observed upon completion of the controlled potential electrolysis of a solution of [M(bpy)3]2+, which results in the precipitation of a dark solid and the almost complete fading of the color of the original solution. Unexpectedly, the crystals do not exhibit an ESR signal. These data indicate the formation of novel materials, crystalline [Fe(bpy)3], [Ru(bpy)3], and [Os(bpy)3]. 相似文献