Chlorosilanes Hydrosilane

When a copper anode is used instead of platinum, the resulting chlorosilane is subsequently reduced to a Si—Si coupling product in a one-pot reaction (equation 49)57. Interestingly, when a mixture of hydrosilane and chlorosilane is electrolyzed using a copper anode and a platinum cathode, a Si—Si coupling product is obtained in 64% yield on the basis of the sum of both reagents used. Thus, the paired electrolysis of hydrosilane on the anode and chlorosilane on the cathode proceeds to give disilane (equation 50)57. 

Their advantage over other types of dendrimers is their straightforward synthesis and, most importantly, their chemical and thermal stabilities. Two distinct steps characterize their synthesis a) an alkenylation reaction of a chlorosilane compound with an alkenyl Grignard reagent, and b) a Pt-cata-lyzed hydrosilylation reaction of a peripheral alkenyl moiety with an appropriate hydrosilane species. Scheme 2 shows the synthesis of catalysts Go-1 and Gi-1 via this methodology. In this case, the carbosilane synthesis was followed by the introduction of diamino-bromo-aryl groupings as the precursor for the arylnickel catalysts at the dendrimer periphery. The nickel centers of the so-called NCN-pincer nickel complexes were introduced by multiple oxidative addition reactions with Ni(PPh3)4. 

Methoxy- and hydrosilanes are reduced at lower values than chlorosilanes. Additionally, the reduction seems to proceed very slowly, because the measured current density is low in comparison with the chlorosilanes. 

The chemistry of sUylene complexes has become much more developed in the past 10 years as silylene complexes have been found to be important intermediates in reactions snch as the dehydrogenative conphng of hydrosilanes, redistribntion reactions, and the Direct Process for the prodnction of simple chlorosilanes. For reviews of this work, see References 43, 44 and 294. Several complexes have now been prepared in which there is a sUene or disilene ligand (R2C=SiR2 or R2Si=SiR2 species) bnt, since all these contain several Si-C bonds, they will not be discnssed further here. 

Silyllithium compounds may also be prepared by the transmetalation reaction between silylmercury and Li. The requisite silylmercury may be prepared from the corresponding chlorosilane or hydrosilane. The latter can be applied to the synthesis of polysilanyllithium. Equation (17) is an example. ... 

In the case of titanium, a number of earlier [2] and more recent [3] studies revealed that Ti-O-Si bonds can be formed using alkoxysilanes [2, 3], chlorosilanes [4], or hydrosilanes [5]. In the latter case, Ti-O-Si bonds resulted from the reaction of surface Ti-OH groups with the reagent s Si-H groups accompanied by molecular hydrogen production. This type of reaction was also shown to be operative between hydrosilanes and Si-OH-containing surfaces [6]. 

While chlorosilanes are valuable starting compounds for preparing the corresponding hydrosilanes, the fluoro derivatives are only of poor preparative interest, but they are important comparison compounds, particularly in the assignment of the Si resonances owing to the characteristic pattern of the Si-F couplings. 

The photolysis of an optically active acetyl silane 1 (eq. [1]) implies the formation of an asymmetric radical 2 which retained its configuration upon trapping by carbon tetrachloride (17). The chlorosilane 3 was then reduced to the hydrosilane 4 with inversion of configuration. 

Lithium aluminium hydride reduction, with inversion of the chlorosilane formed yielded the hydrosilane ([a]D + 20°). Assuming a neat inversion in the reduction step, it appeared that the formation and trapping of the silyl radical occurred with 65% retention. 

To illustrate the serious problem, a case in point is the hydrosilation of allyl chloride which produces equimolar quantities of propene and a chlorosilane as the primary byproducts [Eq. (37)]. The propene can undergo hydrosilation itself leading to a secondary byproduct. Some of the best yields of 3-chloropropylsilane lie in the range 70-80% with a few combinations of hydrosilane and catalyst, but for many useful hydrosilanes, the primary byproducts can be 60% or higher. 

Transformation of hydrosilane to chlorosilane with carbon tetrachloride and benzoyl peroxide 474... 

Transformation of hydrosilane to chlorosilane with carbon tetrachloride in the presence of a palladiumllll chloride catalyst 475 Transformation of hydrosilane to chlorosilane with hydrochloric acid in the presence of a palladiumllll chloride catalyst 475 Selective transformation of dihydrosilane to monochlorosilane with copper(ll chloride in the presence of a copperlll iodide catalyst 476 Transformation of hydrosilane to bromosilane with bromine 477 Transformation of hydrosilane to bromosilane with N-bromosuccinimide (NBSI 478... 

Chlorosilanes are the most important functional silicon compounds. As described above, chlorosilanes can be used for silicon—carbon and silicon—silicon bond formation. In addition, chlorosilanes can be converted into other functional silicon compounds, such as hydrosilanes, alkoxysilanes, and aminosi-lanes. Hydrosilanes, alkoxysilanes, and aminosilanes can be transformed furthermore into other functional silicon compounds. Combination of functional group transformation and silicon-carbon and silicon—silicon bond formation of chlorosilanes are essential for the construction of organosilicon clusters. 

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