Halides, alkyl-silicon

The procedures given by Eqs. (16)—(18) may be used either to alkylate silicon halides or tin halides in very high yields (90-100%), or to substitute the alkyl functions in the metallacycles by halogen atoms. The two products in these reactions can be easily separated from one another and compounds 57-60 are isolated in high yields (63,69). 

Seyferth and coworkers 104 prepared a series of Si-based dendrimers up to the fourth generation. Employing the tetravalent nature of silicon, these macromolecules possessed a tetrahedral, four-directional core, as well as 1 — 3 branching centers. The divergent strategy (Scheme 4.52) utilized two repetitive transformations displacement of halide at silicon with vinylmagnesium bromide (vinylation) and Pt-catalyzed alkyl trichlorosilane formation (hydrosilylation). 

Perfluoroalkyllithium reagents react with electrophiles such as aldehydes, ketones, silicon and tin halides, alkyl halides, carbonates, esters, boron trifluoride-imine complexes, and sulfur dioxide. ... 

Extensive rate studies on aluminum-halide-catalyzed redistributions of organosilanes support a mechanism in which polarization of alkyl silicon bonds and an associative step are essential ... 

Hydrolysis of the alkyl and aryl substituted silicon halides produces silicones (Kipping, 1937). The halogen derivatives themselves are made by passing an alkyl or aryl halide over a copper-silicon alloy at about 300°. Hurd and Rochow (1945) found evidence for the mechanism ... 

Diarylamines can be A/-alkylated with anhydrides and acyl halides or iV-alkjiated with alkyl halides, alkyl sulfates, and tri- -alkylphosphites. Diphenylamine derivatives of alkyl—aryl gallium, germanium, phosphoms, and silicon are known (17), eg, pentaphenylgermanamine [64653-46-9]. 

The starting materials can be prepared through hydrolyses of alkyl or arylsilicone halides. Organosilicone halides, in turn, are made commercially by heating alkyl or aryl halides with silicon at 250-289 °C. This reaction is catalyzed by copper ... 

In the case of triphenylsilane and trityl chloride, this reaction is first order in both reactants in benzene (233). The reaction rate for modified substrates indicates that with respect to R3CX, rate is a function of proclivity to ionize, trityl halides being more rapid than benzhydryl or allyl or tcr/-butyl halides. Indeed the latter required the presence of BBr3 as a catalyst. Within a given series. Cl > Br > I, phenylsilanes react more rapidly than alkyl silanes. A mechanism involving simultaneous nucleophilic attack of halide on silicon, and electrophilic attack on hydrogen by the carbonium ion is reasonable,... 

The following metal compounds are used for the preparation of the catalysts oxides, metal carbonyls, halides, alkyl and allyl complexes, as well as molybdenum, tungsten, and rhenium sulfides. Oxides of iridium, osmium, ruthenium, rhodium, niobium, tantalum, lanthanum, tellurium, and tin are effective promoters, although their catalytic activity is considerably lower. Oxides of aluminum, silicon, titanium, manganese, zirconium as well as silicates and phosphates of these elements are utilized as supports. Also, mixtures of oxides are used. The best supports are those of alumina oxide and silica. 

The reaction is carried out by first reacting the alkyl or aryl halide with magnesium shavings in an ether suspension and then treating with silicon tetrachloride (prepared by passing chlorine over heated silicon). With methyl chloride the following sequence of reactions occur ... 

A. Nucleophilic Reactions of the P=0 Group.—Tris(trifluoromethyl)-phosphine oxide (33) reacts with hexamethyldisiloxane to give a phos-phorane, whose n.m.r. spectrum at — 140 °C shows non-equivalent trifluoromethyl groups. Although this unusual reaction clearly involves nucleophilic attack of the phosphoryl oxygen on silicon at some stage of the reaction, a full study of the mechanism has not been published. Tertiary phosphine oxides can be converted cleanly into dichlorophos-phoranes (34) by treatment with two moles of phosphorus pentachloride. Alkylation of the sodium salt of tetraphenylmethylenediphosphine dioxide (35) with alkyl halides, in dimethyl sulphoxide, has been reported to... 

Aminolysis of the corresponding halides is the preferred method for the synthesis of dialkylamino derivatives of boron,1 silicon,2 germanium,3 phosphorus,4 arsenic,5 and sulfur.6 (Dialkylamino) chlorosilanes are prepared stepwise by the reaction of silicon tetrachloride with dialkylamines. This method may be utilized equally well for the conversion of alkyl- or aryl-substituted halides [e.g., (CH3) SiCl4. ] or of oxide and sulfide halides (e.g., POCl3 or PSC13) to the corresponding dialkylamino compounds. 

Open-chain alkanes, alkyl halide reduction, 29-31 Organosilicon hydrides bond strengths, 5-6 hypervalent silicon species, 9-11 ionic hydrogenation, 5 trivalent silicon species, 7-9 Orthoesters, reduction of, 97-99 Oxime reduction, 102... 

Silicon reacts with alkyl halides at high temperature to yield dialkyl dichlorosilanes. 

Alkyl-substituted silicon peroxides, 78 444 Alkyl sulfates, 23 537 use in cosmetics, 7 849 Alkylsulfones, O-alkylation and, 9 280 Alkyl sulfoxide, micellization of, 24 132t Alkyl tertiary alkyl ethers, 70 575 Alkylthexylboranes, 73 639 Alkyl-thiols, 77 57 4-Alkylthiosemicarbazides, 73 575 Alkyl-tin catalysts, 20 40 Alkyltitanium halides, 25 108—109 Alkyltitaniums, 25 106 higher, 25 116... 

Another application of [Bu4N][Ph3SiF2] 826 involves the silicon-carbon bond cleavage of allyl-, benzyl-, and alkynylsilane derivatives 827-829.826 Subsequent reactions of the generated carbanions with electrophiles (Scheme 112) and alkyl halides (Scheme 113) provide high yields of carbon-carbon coupled products. 

The chemistry of silicone halides was recently reviewed by Collins.13 The primary use for SiCU is in the manufacturing of fumed silica, but it is also used in the manufacture of polycrystalline silicon for the semiconductor industry. It is also commonly used in the synthesis of silicate esters. T richlorosilane (another important product of the reaction of silicon or silicon alloys with chlorine) is primarily used in the manufacture of semiconductor-grade silicon, and in the synthesis of organotrichlorosilane by the hydrosilylation reactions. The silicon halohydrides are particularly useful intermediate chemicals because of their ability to add to alkenes, allowing the production of a broad range of alkyl- and functional alkyltrihalosilanes. These alkylsilanes have important commercial value as monomers, and are also used in the production of silicon fluids and resins. On the other hand, trichlorosilane is a basic precursor to the synthesis of functional silsesquioxanes and other highly branched siloxane structures. 

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