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.
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 figuresPart 1: Nature and role of the hydrolysis products of the methylvinyldichlorosilane in the grafting of silicates in hydrochloric acid and isopropanolThis journal256, 135 (1978). 相似文献
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
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
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
[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
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
The structure of five conformations of the-lac inhibitor clavulanic acid have been optimized using ab initio gradient methods at the 4-21G level. The conformations of lowest energy possess an intramolecular H bond and also have the lowest pyramidization of N1. Different side-chain conformations lead to (i) differences in anomeric interactions and variations of the hydroxyethylidene geometry and (ii) changes in the geometry of the ring skeleton, which are smaller in the four- than in the five-membered ring.On leave from Universidad de Santiago de Compostela, Departamento de Química Física, Facultad de Química, Galicia (Spain). 相似文献
A routing R of a graph G is a set of n(n ? 1) elementary paths R(u, v) specified for all ordered pairs (u, v) of vertices of G. The vertex-forwarding index ξ(G) of G, is defined by Where ξ(G, R) is the maximum number of paths of the routing R passing through any vertex of G and the minimum is taken over all the routings of G. Let Gp denote the random graph on n vertices with edge probability p and let m = np. It is proved among other things that, under natural growth conditions on the function p = p(n), the ratio Tends to 1 in probability as n tends to infinity. 相似文献
Complexes of Dioxocyanogen (OCN)2 with TiCl4 and ZrCl4 A solution of (OCN)2 was obtained by reaction of AgOCN with Br2 in H2CCl2 at ?70°C. From this the complexes TiCl4(NCO)2 and ZrCl4(NCO)2 were obtained by addition of equimolar amounts of TiCl4 and ZrCl4, respectively. According to the i.r. and Raman spectra, the (NCO)2 ligand is bonded via its N atoms to the metal. 相似文献