- Incorporating a silicon unit into a polyether backbone - an effective approach to enhance polyether solubility in CO2
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A series of poly(silyl ether)s were prepared by condensation polymerization and hydrosilation polymerization through incorporating a silicon unit into a polyether backbone. The phase behavior of poly(silyl ether)s in CO2 was measured in terms of concentration, molecular weight and temperature. Through incorporating the silicon unit, the poly(silyl ether)s exhibited high solubility in CO2 compared to the precursors of polyether. For example, the cloud point pressure decreased from 24.6 MPa for poly(1,2-propene glycol) (PPG) to 16.5 MPa for poly(dimethylsiloxane-alt-propene glycol) (PSPG) with a concentration of 0.6 wt% at 30 °C. Moreover, the molecular weight dependence of solubility for PSPG and PSDPG in CO2 compared with PPG was weakened. The key factor to enhance the solubility of poly(silyl ether)s in CO2 was systematically researched via surface tension and glass transition temperature. The results demonstrated that higher solubility of synthesized poly(silyl ether)s in CO2 compared to PPG was mainly attributed to lower polymer-polymer interactions.
- Zhang, Yongfei,Zhu, Zewen,Bai, Zhenguo,Jiang, Wei,Liu, Fengqi,Tang, Jun
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Read Online
- Lactamomethylsilanes – Synthesis, Structures, and Reactivity towards CO2 and Phenylisocyanate
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Lactamomethylsilanes of γ-butyrolactam, δ-valerolactam, ε-caprolactam, and 1-isoindolinone (phthalimidine) with up to three methyl moieties were synthesized according to the chemical formula MexSiLac(4–x) (x = 0, 1, 2, and 3). Using the lactams as starting materials four synthetic routes were tested: salt elimination, transsilylation, transamination, and metallation of the lactames followed by reaction with methylchlorosilanes. All products were analyzed by NMR (1H, 13C and 29Si) and RAMAN spectroscopy. Selected solid products were crystallized and the molecular structure was determined by single-crystal X-ray diffraction. The reactivity of the lactamomethylsilanes towards phenylisocyanate and CO2 was studied.
- Herbig, Marcus,B?hme, Uwe,Kroke, Edwin
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p. 377 - 387
(2019/02/13)
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- Insertion of phenyl isocyanate into monoand diaminosilanes
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The aminosilanes MenSi(NRR')4-n (n = 2,3) with NRR' = ethylamino (NHEt), n-propylamino (NHnPr), sec-butylamino (NHsBu), n-octylamino (NHnOct), n-dodecylamino (NHnDodec), allylamino (NHAll), tert-butylamino (NHtBu), diethylamino (NEt2), and anilino (NHPh) were synthesized and their reactions with phenyl isocyanate were studied. In all cases of these silanes Me3SiNRR' and Me2Si(NRR')2 formal insertion of the -NCO group into their Si-N bonds was observed, i.e. formation of products with Si-N (rather than Si-O) bonds was found. In some cases, the products could be crystallized and their molecular structures have been elucidated with single-crystal X-ray diffraction analyses.
- Kraushaar, Konstantin,Herbig, Marcus,Schmidt, Dana,Wagler, J?rg,B?hme, Uwe,Kroke, Edwin
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p. 909 - 921
(2018/01/19)
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- PREPARATION OF SILAZANE COMPOUND
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A silazane compound useful as synthesis intermediates for paint additives, polymer modifiers, pharmaceuticals and agricultural chemicals is efficiently prepared by reaction of a halosilane compound with an amino-containing compound in a solvent which is the same silazane compound as the target product.
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Paragraph 0034
(2015/11/02)
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- From CO2 to polysiloxanes: Di(carbamoyloxy)silanes Me 2Si[(OCO)NRR′]2 as precursors for PDMS
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Double insertion of carbon dioxide into the Si-N bonds of diaminosilanes of the type Me2Si(NRR′)2 gives di(carbamoyloxy)silanes Me2Si[(OCO)NRR′]2. The reactions proceed exothermically and quantitatively in most cases. A comprehensive analysis of the CO2-insertion products including single-crystal X-ray structure analyses was carried out. Quantum chemical calculations indicate an activation energy of about 124 kJ/mol for both the first and the second insertion and support the exothermal nature of the reaction. Investigation of the thermal decomposition of the di(carbamoyloxy)silanes Me2Si[(OCO)NRR′] 2 reveals the formation of oligo- and polysiloxanes. Depending on the thermolysis parameters, isocyanates, amines, and/or ureas are formed in addition to the siloxanes. Various methods were applied to study the decomposition process and to identify and quantify the products, including thermal analyses, mass spectrometry, and FTIR and NMR (solution and solid-state) spectroscopy. The overall reaction scheme provides a novel route to polysiloxanes which uses carbon dioxide as an oxygen source.
- Kraushaar, Konstantin,Wiltzsch, Conny,Wagler, Joerg,Boehme, Uwe,Schwarzer, Anke,Roewer, Gerhard,Kroke, Edwin
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experimental part
p. 4779 - 4785
(2012/10/07)
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- Aminosilylation of arynes with aminosilanes: Synthesis of 2-silylaniline derivatives
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The nitrogen-silicon σ-bond of aminosilanes added across the triple bond of arynes to give varied 2-silylaniline derivatives straightforwardly. The Royal Society of Chemistry 2005.
- Yoshida, Hiroto,Minabe, Takashi,Ohshita, Joji,Kunai, Atsutaka
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p. 3454 - 3456
(2007/10/03)
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- Synthesis and characterisation of novel zirconium(IV) derivatives containing the bis-amido ligand SiMe2(NRR′)2
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The silicon compounds SiMe2(NRR′)2 [NRR′ = NMe2 (1), NEt2 (2), NC4H8 (3), NHEt (4), NHiPr (5), NHtBu (6), NMeBu (7)] have been synthesised via aminolysis of the dichloro species SiMe2Cl 2 and their ligating ability has been investigated towards zirconium(IV). The dimer zirconium compound {Zr[(NiPr) 2SiMe2]2}2 (8) has been synthesised by reacting ZrCl4 with the lithium salt Li2[(N iPr)2SiMe2] and its molecular structure has been determined in the solid state by X-ray diffraction analysis. The reaction of ZrCl4 with SiMe2(NRR′)2 yields the Lewis adducts ZrCl4[(NRR′)2SiMe2] [NRR′ = NMe2 (10), NC4H8 (11), NHEt (12), NHiPr (13), NHtBu (14), NMeBu (15)]. On the other hand, the mixed amido derivative Zr(NMe2)3(NHMe)[(N′Bu) SiMe2(NH′Bu)] (9) has been obtained from the reaction of Zr(NMe2)4 with SiMe2(NHtBu) 2. The solution molecular structure and dynamics of the zirconium derivatives have been elucidated by 1D and 2D multinuclear NMR spectroscopy.
- Passarelli, Vincenzo,Benetollo, Franco,Zanella, Pierino,Carta, Giovanni,Rossetto, Gilberto
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p. 1411 - 1418
(2007/10/03)
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- A novel route to chlorodimethylsilane
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A new efficient laboratory method of preparation of chlorodimethylsilane (Cl(CH3)2SiH) has been elaborated, which is a modification of the Eaborn et al. method (34) and is based on a transsilylation reaction of substituted (amino)dimethylhydrosilanes, R2NSiMe2H (R2 = Me2, Et2, (CH2)n, etc.) with dimethyldichlorosilane (Me2SiCl2). The reaction proceeds at reflux, at 70°C, preferably with an excess of Me2SiCl2. The most important feature of this novel method is a recovery of intermediate (amino)chlorodimethylsilanes (R2NSiMe2Cl), which can be again reduced to R2NSiMe2H. The transsilylation mechanism has been proven by reaction of (diethylamino)methylphenylsilane with Me2SiCl2. The products of this latter reaction are HMePhSiCl and R2NSiMe2Cl, thus a disproportionation mechanism has been excluded. New substituted bis(amino)dimethylsilanes ((R2N)2SiMe2), (amino)dimethylchlorosilanes (R2NSiMe2Cl), and (amino)dimethylhydrosilanes (R2NSiMe2H) have been synthesized and characterized by NMR and IR.
- Chrusciel
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p. 1405 - 1411
(2007/10/03)
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- Reactions of dihydrofurylsilanes with O- and N-nucleophiles
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It was shown that the reaction of 4,5-dilydro-2-furylsilanes with alcohols and lithium N,N-diethylamide leads to substitution of the dihydrofuryl group by the nucleophilic residue. 1997 Plenum Publishing Corporation.
- Lukevics,Gevorgyan,Borisova
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p. 161 - 163
(2007/10/03)
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- Synthesis of Fluorine Substituted Silicon-Nitrogen Compounds
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Chlorine and bromine substituted silicon nitrogen compounds react in acetonitrile with lithium fluoride to yield the fluorine substituted silicon nitrogen compounds.This reaction, which takes place under moderate conditions, is characterised by high yields.In contrast to other fluorinating agents fission of the silicon nitrogen bond does not occur.The fluorine substituted aminosilanes 1-4 and diaminosilanes 5,6 are synthezised by chlorine/fluorine exchange. 1 is also obtained by bromine/fluorine exchange.
- Hensen, Karl,Pickel, Peter
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p. 223 - 228
(2007/10/02)
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