<b>Redistribution and Reduction Reactions of Alkoxysilanes</b>

Ryan, John W.

doi:10.1021/ja00883a024

Cited by 43 publications

(15 citation statements)

References 2 publications

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“…For example, on heating MeSi-(OEt)3 for 16.5 h at 250°C in the presence of Na one obtains a mixture of Me3SiOEt, Me2Si( OE)P, MeSi ( OEt )3, and Si ( OEt)* . 20 In our case the resins do not contain such a catalyst; on the other hand the reaction temperature is much higher (500-700"C), and uncondensed hydroxyl groups may play an important part, as suggested for the pyrolysis of hydrogenosilsesquioxane ( TH ) gels.21…”

Section: Methylated Polysiloxane Resinsmentioning

confidence: 80%

Thermal redistribution reactions in crosslinked polysiloxanes

Belot

Corriu

Leclercq

et al. 1992

J. Polym. Sci. A Polym. Chem.

125

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The thermolysis under argon of various polysiloxane resins containing D, T, DH, or TH units was investigated using thermogravimetric analysis combined with mass spectroscopy (TG/MS analysis) and solid‐state 29Si‐NMR. Redistribution reactions involving the exchange of SiC/SiO bonds or SiH/SiO bonds were evidenced in addition to the exchange of SiO/SiO bonds reported to date. These reactions significantly modify the initial siloxane units and lead to an escape of volatile silanes or siloxanes. The exchange of SiH/SiO bonds takes place at lower temperatures (300°C) than the exchange of SiC/SiO bonds (500°C).

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Section: Methylated Polysiloxane Resinsmentioning

confidence: 80%

Thermal redistribution reactions in crosslinked polysiloxanes

Belot

Corriu

Leclercq

et al. 1992

J. Polym. Sci. A Polym. Chem.

125

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“…52 This approach identified a host of successful promotors for the iron-catalyzed reaction but was abandoned as we found that any activator sufficiently reducing to generate active [(PDI)Fe] catalysts triggered disproportionation of alkoxy-substituted silanes to pyrrophoric SiH 4 ! 52 These methods and the associated safety hazards were well documented in the literature 53,54,55,56 and generation of even small amounts of silane gas is unacceptable on an industrial scale and hence this route was abandoned. Nevertheless, this route has been widely applied 57 including in high-throughput screening 58 and was re-investigated and published by Thomas and coworkers in 2017.…”

Section: Alkene Hydrosilylationmentioning

confidence: 99%

Earth-abundant transition metal catalysts for alkene hydrosilylation and hydroboration

2018

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The addition of a silicon-hydrogen or a boron-hydrogen bond across a carbon-carbon multiple bonds is a well-established method for the introduction of versatile silane and borane functional groups to base hydrocarbon feedstocks. Transition metal catalysis, historically with precious second- and third- row transition metals, has been used to broaden the scope of the hydrofunctionalization reaction, improve reaction rate and enhance selectivity. The anti-Markovnikov selectivity of platinum-catalyzed hydrosilylation of alkenes, for example, is an enabling synthetic technology in the multibillion-dollar silicones industry. Increased emphasis on sustainable catalytic methods and more economic processes has shifted focus to catalysis with more earth-abundant transition metals such as iron, cobalt and nickel. This review describes contemporary approaches and offers a contextual analysis of catalytic alkene hydrosilylation and hydroboration reactions using first-row transition metals. Emphasis is placed on defining advances in the field, what constitutes catalyst cost, safety, and important design features to enable precious metal-like reactivity, as well as new chemistry that is unique to first-row transition metals.

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“…In addition, this reaction might open new entries for the synthesis of methyl‐ substituted alkoxysilanes Me n Si(OR) 4− n : MeSi(OMe) 3 has been obtained as a byproduct in low yields during the synthesis of HSi(OMe) 3 . The methylation of silicon is best explained by a reduction of, for example, tetramethoxysilane at temperatures between 150–300 °C under the influence of a catalyst, for example, alkali metals, metal halides or hydrides, alkoxides, and amides or organic amines 59a. 66 This is exemplarily shown in Scheme for the treatment of tetramethoxysilane with metallic sodium.…”

Section: Resultsmentioning

confidence: 99%

“…This reaction sequence might be duplicated to give the dimethoxy/dimethyl‐substituted Me 2 Si(OMe) 2 . Alternatively, Ryan favors a reaction sequence according to Equation (2 a, b), :59a …”

Section: Resultsmentioning

confidence: 99%

Amorphous Silicon: New Insights into an Old Material

Spomer

Holl

Zherlitsyna

et al. 2015

Chemistry A European J

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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 Men Si(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 Men Si(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.

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Redistribution and Reduction Reactions of Alkoxysilanes

Cited by 43 publications

References 2 publications

Thermal redistribution reactions in crosslinked polysiloxanes

Thermal redistribution reactions in crosslinked polysiloxanes

Earth-abundant transition metal catalysts for alkene hydrosilylation and hydroboration

Amorphous Silicon: New Insights into an Old Material

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