- N,N-Bis[ethoxy(methyl)silylmethyl]methylamines MeN[CH2SiMem(OEt)3-m]2 (m = 0 - 2). Synthesis and reactions with phenol
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Previously unknown N,N-bis[ethoxy(methyl)silylmethyl]amines MeN[CH2SiMem(OEt)3-m]2 (m = 0-2) were synthesized. According to UV spectral data, only MeN[CH2SiMe2(OEt)]2 form hydrogen bond with phenol in a heptane solution. The amines with m = 0 and 1 fail to forms hydrogen bond with phenol [under the same conditions, N-(triethoxysilylmethyl)dimethylamine Me2NCH2Si(OEt)3 forms a strong hydrogen bond with phenol]. All the amines (m = 0 - 2) enter transetherification with phenol to give compounds of the general formula MeN[CH2SiMem(OPh)n(OEt)3-m-n]2 (m = 0 - 2, n = 1 - 3). Refluxing of N,N-bis[ethoxy(methyl) silylmethyl]amines with excess phenol results in cleavage of the Si-C bond by phenol, providing phenoxysilanes MemSi(OPh)4-m (m = 0 - 2) and trimethylamine.
- Lazareva,Brodskaya
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- Amorphous silicon: New insights into an old material
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Amorphous silicon is synthesized by treating the tetrahalosilanes SiX4 (X=Cl, F) with molten sodium in high boiling polar and non-polar solvents such as diglyme or nonane to give a brown or a black solid showing different reactivities towards suitable reagents. With regards to their technical relevance, their stability towards oxygen, air, moisture, chlorine-containing reaction partners RCl (R=H, Cl, Me) and alcohols is investigated. In particular, reactions with methanol are a versatile tool to deliver important products. Besides tetramethoxysilane formation, methanolysis of silicon releases hydrogen gas under ambient conditions and is thus suitable for a decentralized hydrogen production; competitive insertion into the MeO-H versus the Me-OH bond either yields H- and/or methyl-substituted methoxy functional silanes. Moreover, compounds, such as MenSi(OMe)4-n (n=0-3) are simply accessible in more than 75% yield from thermolysis of, for example, tetramethoxysilane over molten sodium. Based on our systematic investigations we identified reaction conditions to produce the methoxysilanes MenSi(OMe)4-n in excellent (n=0:100%) to acceptable yields (n=1:51%; n=2:27%); the yield of HSi(OMe)3 is about 85%. Thus, the methoxysilanes formed might possibly open the door for future routes to silicon-based products. Amorphous silicon is easily synthesized from tetrahalosilanes SiX4 (X=Cl, F) and molten sodium in different solvents. Reactivity studies prove the resulting materials as versatile tools for the formation of technical important silanes, such as the silicon chloro-, alkoxy-, and methylalkoxy-substituted derivatives (see figure; bl=black, br=brown).
- Spomer, Natalie,Holl, Sven,Zherlitsyna, Larissa,Maysamy, Fariba,Frost, Andreas,Auner, Norbert
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p. 5600 - 5616
(2015/03/30)
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- Reaction of Acetoxysilanes with Hydroxy Compounds
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Tetraacetoxysilane reacts with hexanol, cyclohexanol, and phenol to give products of complete or partial replacement of the acetoxy groups. The rate of hydrolysis of the SiOR group in alkoxy(phenoxy)-silanes and alkoxy(phenoxy)acetoxysilanes in homogeneous (THF) and heterogeneous media (on cellulose surface) increases in the series c=Si-OC6H5 > =Si-OC6H13 > =Si-OC6H11.
- Kopylov, V. M.,Kireev, V. V.,Ivanov, V. V.,Astaf'ev, G. Yu.,Kozlov, Yu. V.
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p. 1924 - 1928
(2007/10/03)
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- Selective synthesis of triphenoxysilane by the reaction of metallic silicon with phenol using copper(I) chloride as the catalyst
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When copper(1) chloride was used as a catalyst in the reaction of silicon with phenol, a high selectivity for triphenoxysilane (HSi(OPh)3) (94%) was obtained, the other product being tetraphenoxysilane (Si(OPh)4). Addition of a small amount of propyl chloride to the feed for poisoning metallic copper enhanced the selectivity for HSi(OPh)3 without affecting the rate of silicon consumption. This result indicates that HSi(OPh)3 is an exclusive primary product and that Si(OPh)4 is formed by the secondary reaction between HSi(OPh)3 and phenol. The reaction mechanism involving surface silylene intermediate is proposed for the formation of HSi(OPh)3 as the sole primary product. The intermediacy of surface silylene was confirmed by adding ethylene in the silicon-phenol reaction to give rise to the trapped product ethyldiphenoxysilane, obtained in a 5.8% selectivity.
- Okamoto, Masaki,Watanabe, Naoto,Suzuki, Eiichi,Ono, Yoshio
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