- 5,6-Disubstituted 1,2,3-trisilaindanes as silicon analogues of phantolide-type musk odorants: Synthesis, structure, reactivity, and olfactory properties
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In an extension of earlier studies concerning drugs and odorants based on disila-substituted tetrahydronaphthalene and indane skeletons, such as the musk odorant disila-phantolide (1), 1-(1,1,2,2,3,3,6-heptamethyl-1,2,3-trisilaindan- 5-yl)ethanone (methyltrisila-phantolide, 2) and a series of related 5,6-disubstituted 1,2,3-trisilaindanes (3-5) were prepared in multistep syntheses. Compounds 2-5 were characterized by 1H, 11B (5 only), 13C, and 29Si NMR studies. In addition, compounds 3-5 were studied by single-crystal X-ray diffraction. The 1,2,3-trisilaindane skeleton proved to have limited stability toward oxidation agents. The oxidation product 6, a novel 1,3,4-trisilaisochroman system, was isolated and characterized. The trisila-phantolide derivatives 2 and 3 do not display a typical musk odor, but instead possess a slightly creamy-lactonic odor with coumarinic aspects of very weak intensity (odor thresholds, >500 ng L -1 air).
- Gluyas, Josef B. G.,Burschka, Christian,Kraft, Philip,Tacke, Reinhold
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- CHLORINATIVE CLEAVAGE OF PERMETHYLPOLYSILANES INITIATED BY PHOTO-INDUCED ELECTRON TRANSFER
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Irradiation od dodecamethylcyclohexasilane (1) in CCl4-CH2Cl2 in the presence of 9,10-dicyanoanthracene (2) afforded 1,6-dichlorododecamethylsilane in 70percent yield.Fluorescence of 2 was quenched by 1 with a diffusion-controlled rate.A mechanism of free-radical chlorination involving (1)+ is proposed.
- Nakadaira, Yasuhiro,Komatsu, Norio,Sakurai, Hideki
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- Gas-phase reactions of silicon-centred intermediates with chlorofluorocarbons
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Pyrolysis of pentamethyldisilane in the presence of a CFC, dichlorodifluoromethane, efficiently replaced chlorine by hydrogen in the CFC, with concomitant formation of chlorosilanes. Although the primary intermediate in this pyrolysis is dimethylsilylene, there was strong evidence that conversions resulted from reactions of organosilyl and alkyl radicals. Experiments to confirm this conclusion are described, and mechanisms are discussed. Two independent measurements of the activation energy difference between chlorine-and fluorine-abstraction from dichlorodifluoromethane by trimethylsilyl radicals gave concordant values of 52 ± 5 kJ mol-1. The reactions described are of interest in relation to the environmental importance of dechlorinating CFCs.
- Clarke, Michael P.,Conqueror, Martin,Morgan, Geraint H.,Davidson, Iain M.T.
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- CLEAVAGE OF METHYLDISILANES TO METHYLMONOSILANES
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The invention relates to a process for the manufacture of methylmonosilanes comprising the step of subjecting one or more methyldisilanes to the cleavage reaction of the silicon-silicon bond, and optionally a step of separating the resulting methylmonosilanes.
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Page/Page column 28; 29
(2019/04/16)
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- Making Use of the Direct Process Residue: Synthesis of Bifunctional Monosilanes
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The industrial production of monosilanes MenSiCl4?n (n=1–3) through the Müller–Rochow Direct Process generates disilanes MenSi2Cl6?n (n=2–6) as unwanted byproducts (“Direct Process Residue”, DPR) by the thousands of tons annually, large quantities of which are usually disposed of by incineration. Herein we report a surprisingly facile and highly effective protocol for conversion of the DPR: hydrogenation with complex metal hydrides followed by Si?Si bond cleavage with HCl/ether solutions gives (mostly bifunctional) monosilanes in excellent yields. Competing side reactions are efficiently suppressed by the appropriate choice of reaction conditions.
- Sturm, Alexander G.,Santowski, Tobias,Schweizer, Julia I.,Meyer, Lioba,Lewis, Kenrick M.,Felder, Thorsten,Auner, Norbert,Holthausen, Max C.
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supporting information
p. 8499 - 8502
(2019/06/13)
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- Synthesis of Functional Monosilanes by Disilane Cleavage with Phosphonium Chlorides
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The Müller–Rochow direct process (DP) for the large-scale production of methylchlorosilanes MenSiCl4?n (n=1–3) generates a disilane residue (MenSi2Cl6?n, n=1–6, DPR) in thousands of tons annually. This report is on methylchlorodisilane cleavage reactions with use of phosphonium chlorides as the cleavage catalysts and reaction partners to preferably obtain bifunctional monosilanes MexSiHyClz (x=2, y=z=1; x,y=1, z=2; x=z=1, y=2). Product formation is controlled by the reaction temperature, the amount of phosphonium chloride employed, the choice of substituents at the phosphorus atom, and optionally by the presence of hydrogen chloride, dissolved in ethers, in the reaction mixture. Replacement of chloro by hydrido substituents at the disilane backbone strongly increases the overall efficiency of disilane cleavage, which allows nearly quantitative silane monomer formation under comparably moderate conditions. This efficient workup of the DPR thus not only increases the economic value of the DP, but also minimizes environmental pollution.
- Santowski, Tobias,Sturm, Alexander G.,Lewis, Kenrick M.,Felder, Thorsten,Holthausen, Max C.,Auner, Norbert
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supporting information
p. 3809 - 3815
(2019/02/13)
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- One-Step Synthesis of Siloxanes from the Direct Process Disilane Residue
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The well-established Müller–Rochow Direct Process for the chloromethylsilane synthesis produces a disilane residue (DPR) consisting of compounds MenSi2Cl6?n(n=1–6) in thousands of tons annually. Technologically, much effort is made to retransfer the disilanes into monosilanes suitable for introduction into the siloxane production chain for increase in economic value. Here, we report on a single step reaction to directly form cyclic, linear, and cage-like siloxanes upon treatment of the DPR with a 5 m HCl in Et2O solution at about 120 °C for 60 h. For simplification of the Si?Si bond cleavage and aiming on product selectivity the grade of methylation at the silicon backbone is increased to n≥4. Moreover, the HCl/Et2O reagent is also suitable to produce siloxanes from the corresponding monosilanes under comparable conditions.
- Neumeyer, Felix,Auner, Norbert
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supporting information
p. 17165 - 17168
(2016/11/23)
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- Surface Active Organosilicone Compounds
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The present invention relates to new organodisilanes or carbodisilanes, a process for manufacturing the same and their use, in particular, as surface active agents, especially as spreading agents.
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Page/Page column 6-7
(2008/12/09)
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- Kinetic Control in the Cleavage of Unsymmetrical Disilanes
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A series of 12 phenyl-substituted arylpentamethyldisilanes 1a-1 have been synthesized in order to examine the regioselectivity of their nucleophilic Si,Si bond cleavage reactions under Still's conditions (MeLi/HMPA/0°C). It has been found that the sensitivity of these reactions to the electronic effects of the substituents in the phenyl ring could be described by the Hammett-type equation log(kA/kB) = 0.4334 + 2.421(Σσ); (correlation coefficient R = 0.983). The kA/kB ratio represents the relative rate of attack at silicon atom A (linked to the aryl ring) or at silicon atom B (away from the aryl ring) of the unsymmetrical disilanes. Thus, the present investigation shows that the earlier belief according to which the nucleophilic cleavage of unsymmetrical disilanes always produces the more stable silyl anionic species (thermodynamic control) should be abandoned, or at least seriously amended: kinetic factors appear to exert a primary influence on the regioselectivity of such reactions. Since the two major kinetic factors (i.e., electrophilic character of and steric hindrance at a given silicon atom) have opposite effects on the orientation of the reaction, it may happen that kinetic and thermodynamic control lead to the same result. For some of the unsymmetrical disilanes studied, the major reaction path was not the Si,Si bond cleavage; instead, Si-aryl bond breaking occurred, producing the corresponding aryl anions.
- Hevesi, Laszlo,Dehon, Michael,Crutzen, Raphael,Lazarescu-Grigore, Adriana
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p. 2011 - 2017
(2007/10/03)
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- Method for introducing hydrocarbons into chlorosilanes
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By reacting a chloromonosilane or chlorodisilane with a halogenated hydrocarbon in a liquid phase in the presence of metallic aluminum or an aluminum alloy, a hydrocarbon group is substituted for at least one chlorine atom of the chlorosilane for introducing hydrocarbon into the chlorosilane. Silanes having a high degree of hydrocarbon substitution can be easily synthesized from chlorosilanes under moderate conditions and with high volumetric efficiency. The reagents used are aluminum or aluminum alloys and halogenated hydrocarbons which are inexpensive and readily available.
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- Ligand Exchange Reactions between Haloboranes and Alkylsilanes
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In a ligand exchange reaction between BHal3 (Hal = Cl, Br) and the tetraalkylsilanes Et4Si, (Me3Si)2CH2 or Ph2CHSiMe3 the alkylhaloboranes EtBBr2 or MeBHal2 and the alkylhalosilanes Et3SiBr, HalMe2Si-CH2-SiMe3, (HalMe2Si)2CH2, and Ph2CHSiMe2Br, respectively, are formed.Similarly, the methyloligosilanes (Me3Si)2 (1) and (Me3Si)2SiMe2 (2) react with BHal3 (Hal = Cl, Br, I) via methyl-halogen-transfer to give HalMe2Si-SiMe3 (Hal = Cl, Br, I), (HalMe2Si)2 (Hal = Br, I), HalMe2Si-SiMe2-SiMe3, (Me3Si)2SiMeHal, HalMe2Si-SiMeHal-SiMe3, (HalMe2Si)SiMe2 (Hal = Cl, Br) or (BrMe2Si)2SiMeBr besides MeBHal2 (Hal = Cl, Br, I) and Me2BI, respectively.
- Einholz, Wolfgang,Gollinger, Walter,Haubold, Wolfgang
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- The synthesis of novel chlorosilyl and chlorogermyl mercurials with some of their chemical reactions
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When a mercury alkyl is irradiated in the presence of trichlorosilane, bis(trichlorosilyl)mercury, a white crystalline solid, and the alkane are formed. In a similar reaction with methyldichlorosilane, bis(methyldichlorosilyl)mercury is a product. With trichlorogermane as a reactant a similar light-induced reaction produces bis(trichlorogermyl)mercury. These novel mercurials react with compounds possessing a silicon-hydrogen bond to form disilanes. Preparations are described for methylpentachlorodisilane, 1,1-dimethyltetrachlorodisilane, 1,2-dimethyltetrachlorodisilane, 1,1,1,-trimethyltrichlorodisilane, 1,1,2-trimethyltrichlorodisilane, 1,1,1,2-tetramethyldichlorodisilane, 1,1,2,2-tetramethyldichlorodisilane, pentamethylchlorodisilane, trichlorosilyltrichlorogermane, and trimethylsilylmethyltrichlorogermane using various modifications of this reaction. Syntheses have been devised for the mercurials, bis(trichlorosilyl)mercury, bis(methyldichlorosilyl)mercury, bis(trichlorogermyl)mercury, and (trimethylsilylmethyl)trichlorogermylmercury. Bis(dimethylchlorosilyl)mercury is formed at low temperatures but decomposes at temperatures above -79°. Bis(trichlorosilyl)mercury also reacts with dimanganese decacarbonyl to form trichlorosilylmanganese pentacarbonyl.
- Bettler, Charles R.,Sendra, Joseph C.,Urry, Grant
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p. 1060 - 1065
(2007/10/05)
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