Halides silanes

Metathesis. MTO is active in alkene metathesis when activated by a co-catalyst such as S4N4/AICI3, or supported on silica or alumina. In the original communication of Hermann et al., the self-metathesis of allylic halides, silanes and unsaturated car-boxylates and nitriles was achieved using MT0/Al203-Si02 as the catalytic system (eq 35). 

The normal boding points of some halide silanes are reported below. Explain the order in terms of intermolecular forces. 

Halogen derivatives of silanes can be obtained but direct halogena-tion often occurs with explosive violence the halogen derivatives are usually prepared by reacting the silane at low temperature with a carbon compound such as tetrachloromethane, in the presence of the corresponding aluminium halide which acts as a catalyst. 

Halogens, Hydrogen Halides, and Other Covalent Halides. Most compounds containing Si—H bonds react very rapidly with the free halogens. An explosive reaction takes place when chlorine or bromine is allowed to react with SiH at room temperature, presumably forming halogenated silane derivatives (3). At lower temperatures, the reactions are moderated considerably, for example. 

Ailyl sulfides, sulfonates, halides, phosphonates, silanes... 

Table 6.9 Transfer Constants for Ally Halides, Phosphonates, Silanes and...

Vinyl Acetate CH3COOCH=CH2 OH compds, HCN, Halides, Halogens, Mer-cap tans, Amine, Silanes Oxygen Vap in Air 2.6 to 13.4% > Ambient > Ambient Inhibitor—Methyl Ether of Hydroquinone or 3-5ppm Diphenylamine. Store in a dry, cool place shield from light impurities 20.9-21.5 402 427 Free-radical polymerization initiated by Benzoyl Peroxide... 

Because carbon bonds so readily with itself, there are many hydrocarbons (see Chapter 18). Silicon forms a much smaller number of compounds with hydrogen, called the silanes. The simplest silane is silane itself, SiH4, the analog of methane. Silane is formed by the action of lithium aluminum hydride on silicon halides in ether ... 

CVD Reactions. MoSi2 is usually deposited by the reaction of a molybdenum halide with silane. The simplified reactions are as... 

Radical-mediated silyldesulfonylation of various vinyl and (a-fluoro)vinyl sulfones 21 with (TMSlsSiH (Reaction 25) provide access to vinyl and (a-fluoro)vinyl silanes 22. These reactions presumably occur via a radical addition of (TMSlsSi radical followed by /)-scission with the ejection of PhS02 radical. Hydrogen abstraction from (TMSlsSiH by PhS02 radical completes the cycle of these chain reactions. Such silyldesulfonylation provides a flexible alternative to the hydrosilylation of alkynes with (TMSlsSiH (see below). On oxidative treatment with hydrogen peroxide in basic aqueous solution, compound 22 undergoes Pd-catalyzed cross-couplings with aryl halides. 

Allylic silanes react with aldehydes, in the presence of Lewis acids, to give an allyl-substituted alcohol. In the case of benzylic silanes, this addition reaction has been induced with Mg(C104)2 under photochemical conditions. The addition of chiral additives leads to the alcohol with good asymmetric induction. In a related reaction, allylic silanes react with acyl halides to produce the corresponding carbonyl derivative. The reaction of phenyl chloroformate, trimethylallylsilane, and AICI3, for example, gave phenyl but-3-enoate. ... 

Silicon, like carbon, is relatively inactive at ordinary temperatures. But, when heated, it reacts vigorously with the halogens (fluorine, chlorine, bromine, cmd iodine) to form halides and with certain metals to form silicides. It is unaffected by all acids except hydrofluoric. At red heat, silicon is attacked by water vapor or by oxygen, forming a surface layer of silicon dioxide. When silicon and carbon are combined at electric furnace temperatures of 2,000 to 2,600 °C (3,600 to 4700 °F), they form silicon carbide (Carborundum = SiC), which is an Importeint abrasive. When reacted with hydrogen, silicon forms a series of hydrides, the silanes. Silicon also forms a series of organic silicon compounds called silicones, when reacted with various organic compounds. 

Interesting cyclic ionic species are obtained from the reactions of di(phosphazenyl)silanes with silicon halides at room temperature ... 

Both trialkylsilyl and trialkylstannyl halides usually give high yields of substitution products with organolithium reagents, and this is an important route to silanes and stannanes (see Section 9.2.1 and 9.3.1). 

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