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Grafting reactions of phenyl groups on silica substrates using as reagents various phenylsilanes with variable distances between the silicon atoms and the aromatic ring by 0, 1, and 2 methylene groups [Si–(CH2)
n
–C6H5] were studied. Two different silicates have been selected as source of silica: sepiolite and tetraethyl-orthosilicate (TEOS). Sulfonic- and nitro-derivatives prepared from these phenyl compounds by electrophilic substitution reactions, have been obtained. The mechanism of these processes has been studied in relation to the number of methylene separating groups belonging to the starting reagents. The characterization of such systems has been achieved by XRD,29Si and13C NMR/MAS, IR, and laser microprobe mass spectrometry.Parts I, II and III published in this Journal (1978) 256:135–139, (1979) 257:178–181 and (1985) 263:1025–1030 相似文献
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Molecularly Designed Nanoparticles by Dispersion of Self‐Assembled Organosiloxane‐Based Mesophases 下载免费PDF全文
Shigeru Sakamoto Yasuhiro Tamura Dr. Hideo Hata Dr. Yasuhiro Sakamoto Prof. Atsushi Shimojima Prof. Kazuyuki Kuroda 《Angewandte Chemie (International ed. in English)》2014,53(35):9173-9177
The design of siloxane‐based nanoparticles is important for many applications. Here we show a novel approach to form core–shell silica nanoparticles of a few nanometers in size through the principle of “dispersion of ordered mesostructures into single nanocomponents”. Self‐assembled siloxane–organic hybrids derived from amphiphilic alkyl‐oligosiloxanes were postsynthetically dispersed in organic solvent to yield uniform nanoparticles consisting of dense lipophilic shells and hydrophilic siloxane cores. In situ encapsulation of fluorescent dyes into the nanoparticles demonstrated their ability to function as nanocarriers. 相似文献
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E. A. Rebrov N. A. Tebeneva A. M. Mouzafarov Yu. E. Ovchinnikov Yu. T. Struchkov T. V. Strelkova 《Russian Chemical Bulletin》1995,44(7):1286-1292
The hydrolytic condensation of methyltris(methyldichlorosiloxy)silane (1b), methyl(1a), and vinyltris(methyldiethoxysiloxy)silanes (1c) in dilute homogeneous solutions was studied. It was found by X-ray diffraction and1H NMR methods that, irrespective of reaction conditions, only octaorganooctasilsesquioxanes (T
8), namely, octamethyloctasilsesquioxane and 1,4-divinylhexamethyloctasilsesquioxane, were obtained instead of the expected tetraorganotetrasilsesquioxanes (T
4). These data suggest that the condensation processes involved in the hydrolysis of1a–c are predominantly intermolecular, and the molecules of the starting oligomers do not undergo rearrangements. Probably, the formation ofT
4, whose molecules are built of four strained six-membered organosiloxane cycles, is less favorable thermodynamically than the formation of their homologs (T
8) built of eightmembered organosiloxane cycles.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1332–1339, July, 1995. 相似文献
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Inside Cover: Molecularly Designed Nanoparticles by Dispersion of Self‐Assembled Organosiloxane‐Based Mesophases (Angew. Chem. Int. Ed. 35/2014) 下载免费PDF全文
6.
Phosphazene-containing porous materials are of a great interest due to their unique properties, caused by the synergetic presence of nitrogen and phosphorus atoms, and have found applications as adsorbents, basic catalysts, etc. On the other hand, cage-like silsesquioxanes are ideal building blocks for the preparation of covalently-linked porous materials. Here two new phosphazene-functionalized organosilsesquioxane cage-based porous polymers were synthesized successively by a Friedel-Crafts reaction of hexapyrrolylcyclotriphosphazene with octavinylsilsesquioxane in the presence of AlCl3 and CF3SO3H as catalysts. The nature of acid catalysts barely influenced the character of pores due to the interaction of catalysts with basic nitrogen atoms of phosphazene units. The obtained polymers exhibited high efficiency as metal-free catalysts for the Knoevenagel reaction. This work opens new perspectives in the use of porous polymers based on cage-like organosiloxane compounds as basic catalysts for various reactions. 相似文献
7.
O. Mukbaniani G. Zaikov T. Tatrishvili N. Mukbaniani Kh. Koberidze 《Macromolecular Symposia》2007,247(1):411-419
The reaction of hydride polyaddition of methylhydridesiloxane and methylhydridesiloxane-dimethylsiloxane oligomers to unsaturated carbocyclic compound - tricyclodecadiene, at the various ratio of initial compounds, in the presence of platinum hydrochloric acid has been investigated. It was shown that hydrosilylation reaction proceeds both to 1.2 and 9.10 positions and by intermolecular with formation of branching systems. The polyorganosiloxanes with tricyclodecenyl fragment in the side chain, completely soluble in organic solvents were synthesized. For fully characterization of hydride addition of methylhydridesiloxane to tricyclodecadiene, by quantum-chemical half empiric AM1 method, for all initial, intermediate and final products, in modelling reaction of hydrosilylation of methyldimethoxysilane to tricyclodecadiene, the heats of formations (ΔHf), change of energy (ΔH) of the system depending on the change of distance (RC-Si) between C-Si bonds, also the charges values (q) on the atoms, dipole moments (µ) and bonds orders (Pij) are calculated. It was concluded, that the course of hydride addition of modelling reaction of methyldimethoxysilane to tricyclodecadiene energetically is more favourable by 9.10-addition. The hydride polyaddition reaction order, activation energies and rate constants were found. The synthesized oligomers were characterized by 1H and 13C NMR, FTIR, thermogravimetry, gel permeation chromatography, differential scanning calorimetry and wide angle X-ray methods. 相似文献
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《Mendeleev Communications》2022,32(2):164-166
MQ resins have been prepared in acetic acid as an active medium from dimethylphenyl- or methyldiphenylethoxy-silane as the M-components and tetraethoxysilane as the Q-component. All prepared samples with M/Q ratios of 1:1, 1:1.5, 1:2, 1:3, and 1:4 were well soluble in organic solvents like toluene and THF. Compared to MQ resins with trimethylsilyl group as the M-component, the new MQ resins with phenyl substituents may possess improved compatibility to thermoplastic polymers, rubbers and coating formulations. 相似文献
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A. N. Bilyachenko B. G. Zavin E. S. Shubina A. M. Filin M. M. Levitskii 《Russian Chemical Bulletin》2004,53(9):1993-1995
Intermolecular rearrangement of cobalt phenylsiloxanes was studied. The rearrangement leads to the formation of compounds with metal oxide moieties in the organosiloxane structure and is accompanied by a change in the spectral characteristics of cobalt(II), determined by the second coordination sphere of the metal. The rate-determining step is the decomposition of an intermediate complex formed upon the coordination of the metal siloxane moieties.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1912–1914, September, 2004. 相似文献
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