نتایج جستجو برای: silanes
تعداد نتایج: 586 فیلتر نتایج به سال:
Abstract In view of the serious erosion problem gun barrel with R2 high-energy propellant, an tube device method was adopted, and silane organic substances, silicate inorganic titanium dioxide nanoparticles paraffin wax were selected as erosion-reducing additives. The effect different additives on erosive property propellant investigated by means external addition. inhibition principle also bri...
The first enantioselective organocatalytic α-allylation of cyclic ketones has been accomplished via singly occupied molecular orbital catalysis. Geometrically constrained radical cations, forged from the one-electron oxidation of transiently generated enamines, readily undergo allylic alkylation with a variety of commercially available allyl silanes. A reasonable latitude in both the ketone and...
Phosphazene superbases are efficient organocatalysts for the metal-free catalytic hydrosilylation of carbon dioxide. They react with CO2 to form the respective phosphine oxides, but in the presence of hydrosilanes, CO2 can be selectively reduced to silyl formates, which can in turn be reduced to methoxysilanes by addition of an extra loading of silanes. Activities reach a TOF of 32 h(-1) with a...
We report on the synthesis and characterization of functional silica hybrid magnetic nanoparticles (SHMNPs). The co-condensation of 3-aminopropyltriethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) in presence of superparamagnetic iron oxide nanoparticles (SPIONs) leads to hybrid magnetic silica particles that are surface-functionalized with primary amino groups. In this work, a comprehe...
Objective This project is investigating the use of carbon nanotubes (CNT) for transparent conducting electrodes in photovoltaic applications. In order to decrease the sheet resistance, both the electronic properties of the CNTs – namely the tube conductivity and tube-to-tube contact resistance – and the sheet morphology have to be controlled. This research aims to reach this target through the ...
The first efficient and non-precious nanoparticle catalyst for alkene hydrosilylation with commercially relevant tertiary silanes has been developed. The nickel nanoparticle catalyst was prepared in situ from a simple nickel alkoxide precatalyst Ni(O(t) Bu)2 ⋅x KCl. The catalyst exhibits high activity for anti-Markovnikov hydrosilylation of unactivated terminal alkenes and isomerizing hydrosily...
In an influential paper, La Porta, Lopez-De-Silanes and Shleifer (2002) argued that public ownership of banks is associated with lower GDP growth. We show that this relationship does not hold for all countries, but depends on a country’s financial development and political institutions. Public ownership is harmful only if a country has low financial development and low institutional quality. Th...
that every single material derived from silicon chemistry seems extremely modern. Silicon occurs naturally in sand and rocks, generally in the form of silica and silicate, and is the second most abundant element on earth after oxygen. Only crystalline silicon and the silanes and organosiloxanes are truly modern products: they do not occur freely in nature, but are entirely the product of human ...
Heterocyclic silanes containing Si-N or Si-S bonds in the ring undergo a ring opening reaction with -OH groups at the surface of porous Si nanostructures to generate -SH or -NH functional surfaces, grafted via O-Si bonds. The reaction is substantially faster (0.5-2 h at 25 °C) and more efficient than hydrolytic condensation of trialkoxysilanes on similar hydroxy-terminated surfaces, and the rea...
A sulfoxide-directed, metal-free ortho-propargylation of aromatics and heteroaromatics exploits intermolecular delivery of a propargyl nucleophile to sulfur followed by an intramolecular relay to carbon. The operationally simple cross-coupling procedure is general, regiospecific with regard to the propargyl nucleophile, and shows complete selectivity for products of ortho-propargylation over al...
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