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31.
Highly Selective Hydrothiolation of Unsaturated Organosilicon Compounds Catalyzed by Scandium(III) Triflate 下载免费PDF全文
Krzysztof Kuciński Dr. Piotr Pawluć Prof. Dr. Bogdan Marciniec Dr. Grzegorz Hreczycho 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(13):4940-4943
The first use of a Lewis acid catalyst in the addition reaction of both aromatic and aliphatic thiols to unsaturated organosilicon compounds is reported. In catalytic tests, scandium(III) triflate demonstrates high catalytic activity in this process. Under mild conditions (25 °C, room temperature, 1–10 h) a number of thioether‐functionalized organosilicon species are obtained with appreciable selectivity. This study constitutes the first example of allylsilane hydrothiolation that gives the Markovnikov regioisomer as the main product. Ethynylsilanes are also successfully used in the hydrothiolation reaction in the presence of Sc(OTf)3. 相似文献
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33.
Synthesis of octakis({3-glycidoxypropyl}dimethylsiloxy) octasilsesquioxane (G-POSS) was carried out based on a reaction involving the hydrosilylation of allyl glycidyl ether with octakis(dimethylsiloxy) octasilsesquioxane, using Karstedt’s catalyst and toluene. SiO2/POSS hybrid systems were obtained via a method of immobilization by evaporation of the solvent, using hydrated or spherical silica obtained by precipitation in an aqueous or emulsion environment. The surface of the SiO2 was modified using octakis({3-glycidoxypropyl}dimethylsiloxy) octasilsesquioxane (G-POSS). The effectiveness of the modification of the obtained hybrid materials was verified using Fourier transform infrared spectroscopy and nuclear magnetic resonance (29Si and 13C CP MAS NMR). The tests showed that the interactions between the silica support and the modifier are of the nature of chemical adsorption. In addition a mechanism was proposed for the interactions between silica and oligosilsesquioxane. To test the final effect, the hybrid systems were subjected to morphological evaluation (transmission electron microscopy). Parameters of porous structure of the products were also determined: the specific surface area, pore diameter and pore volume. Thermal stability was tested for the pure silsesquioxane cage, the initial silica supports and the resulting systems. Elemental analysis was also carried out to determine the effect of surface modification on the degree of coverage with a particular POSS compound. 相似文献
34.
M. Dutkiewicz M. Szołyga H. Maciejewski B. Marciniec 《Journal of Thermal Analysis and Calorimetry》2014,117(1):259-264
Epoxy resin-based composites, also those containing POSS compounds, have been the subject of extensive research because of their attractive properties and broad practical applications. However, in some applications they suffer from too long curing times or not strong enough adhesion to metals. A solution to this problem is the use of episulfide (thiirane) derivatives or their combination with epoxies. In this paper, the synthesis of new octakis[(3-(thiiran-2-yloxy)propyl)dimethylsiloxy]octasilesquioxane from its 3-glycidoxypropyldimethylsiloxy analog is described. Results of study of its influence on thermal properties as well as curing processes of modified with this compound epoxy resins hardened with maleic, phthalic, and pyromellitic anhydrides are also presented. It is shown that addition of this new thiirane functional POSS compound can significantly increase thermal stability of obtained epoxy resin composites and decrease its curing temperatures. 相似文献
35.
Magdalena Ogrodowczyk Barbara Marciniec Piotr Kachlicki 《Central European Journal of Chemistry》2014,12(1):60-66
Pindolol ((2RS)-(1-(1H-indol-4-iloxy)-3- [(1-metyloetylo)amino]-2-propanol) in substantia was exposed to ionising radiation emitted by high energy electrons from an accelerator, in the standard sterilisation dose of 25 kGy and in higher doses from the range 50–400 kGy. The effects of irradiation were checked by spectrometric methods (UV, MS, FT-IR, EPR) and hyphenated methods (HPLC-MS) and the results were referred to those obtained for non-irradiated sample. EPR results indicated the presence of free radicals in irradiated samples, in the amount of 1.36 × 1016 spin g?1 for 25 kGy and 3.70×1016 spin g?1 for 400 kGy. The loss of pindolol content determined by HPLC was 1.34% after irradiation with 400 kGy, while the radiolytic yield of the total radiolysis for this dose of irradiation was 2.69×107 mol J?1. By means of HPLC-MS it was possible to separate and identify one product of radiolytic decomposition, which probably is 2-((R)-3-(1H-indol-4-yloxy)-2-hydroxypropylamino)propan-1-ol formed upon oxidation. In the range of sterilisation doses (25–50 kGy), pindolol was found to show high radiochemical stability and would probably be safely sterilised by the standard dose of 25 kGy. 相似文献
36.
1-(Trimethylsilyl)-1-alkenes of general formula CH3(CH2)nCH?CHSi(CH3)3, where n = 3–15, have been prepared by a novel method, viz. by an effective cross-metathesis of vinyltrimethylsilane with 1-alkenes catalyzed by RuCl2(PPh3)3. Excess of 1-alkene in the reaction mixture gave 1-(trimethylsilyl)-1-alkenes in good yields of up to 60% (in terms of vinylsilane). The products were identified by NMR spectroscopic (1H, 13C NMR) and GC MS methods. 相似文献
37.
A cyclohexanone solution of H2PtCl6 was examined to find the catalytic species responsible for the hydrosilylation of the olefinic C=C bond. Similarly to other H2PtCl6–solvent systems (e.g. Speier's and Karstedt's catalysts), the real catalyst appeared to be colloidal platinum formed in situ by stepwise reduction [Pt(IV)→Pt(O)] and dechlorination of the platinum precursor. The role of cyclohexanone seems to be to form sufficiently stable platinum complexes to avoid rapid platinum precipitation and aggregation. The studies of H2PtCl6–solvent systems are of practical importance since these compounds are widely used catalyst precursors for hydrosilylation on an industrial scale. 相似文献
38.
Walkowiak J Jankowska-Wajda M Marciniec B 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(22):6679-6686
Vinyl-substituted boronates in the presence of complexes containing Ru-H bonds (preferably [Ru(CO)ClH(PCy(3))(2)], Cy: cyclohexyl) react regioselectively with terminal ethynes (involving silylethynes), albeit with the exception of phenylacetylene, to produce boryl- and borylsilyl-substituted buta-1,3-dienes with a preference for E,E-diene. The reaction opens a new catalytic route for the preparation of dienylboronates, and particularly dienylsilylboronates, that are functionalised building blocks in the synthesis of organic and natural products. The mechanism of this new reaction was proved to involve an insertion of alkyne into Ru-H bonds followed by an insertion of coordinated vinyl boronate into the Ru-C= bond and beta-hydrogen transfer to the metal to eliminate boryldiene or borylsilyldiene. 相似文献
39.
Marciniec B Kownacki I Franczyk A Kubicki M 《Dalton transactions (Cambridge, England : 2003)》2011,40(18):5073-5077
The first bi- and mononuclear rhodium(I) complexes [{Rh(μ-OSi(8)O(12)(i-Bu)(7))(cod)}(2)] (5), [Rh(cod)(PCy(3))(OSi(8)O(12)(i-Bu)(7))] (6) with a hindered hepta(iso-butyl)silsesquioxyl ligand bonded to the rhodium(I) center through Rh-O-Si bonds have been synthesized and their structures have been solved by spectroscopic methods and X-ray analysis. Their exemplary catalytic properties in silylative coupling of vinylsilanes with styrene are also presented. 相似文献
40.
Barbara Marciniec Katarzyna Dettlaff Marek Naskrent Zuzanna Pietralik Maciej Kozak 《Journal of Thermal Analysis and Calorimetry》2012,108(1):33-40
The effect of ionising radiation on the physico-chemical properties of disulfiram (Antabuse, Esperal, bisdiethylthiocarbamoil
disulphide) has been studied by DSC, FTIR, EPR, MS, TLC and HPLC. Sterilisation was carried out in the solid state, at room
temperature and normal air humidity using the electron beam of 9.96 Mev from accelerator. All the measurements were made simultaneously
for the irradiated and nonirradiated substance. It has been found that the drug studied in solid phase when subjected to an
electron beam corresponding to the irradiation in the doses 10–100 kGy shows the presence of free radicals (EPR), and a change
in colour from white to pale green-grey that disappears after solution in water or methanol. After the irradiation with the
dose of 100 kGy, its melting point and enthalpy slightly decreased. Also the content of the active substance decreases (HPLC
−1.5%, UV −3.6%, iodometric titration method −2.7%) and trace amounts of the radiolysis products appear (HPLC). The substance
irradiated with the doses 10–50 kGy does not show changes in the melting point, in the content and presence of the radiolysis
products. The EPR results have shown that free radicals disappear after about a year and the discolouring disappears with
them. The results of this study have shown that disulfiram can be subjected to sterilisation by irradiation with no deterioration
of its physico-chemical properties, but a long time of storage needed to remove free radicals and discolouration questions
the economic justification for this type of sterilisation. 相似文献