Silicon-carbon bond reaction

Silicon—Carbon Bond-Forming Reactions. After the Rochow-MbUer direct process, the hydro silylation reaction (139),... 

The polarity of the silicon-carbon bond will affect the manner in which the reaction with ions and molecules takes place. For example, on reaction with... 

C. Eabom and R. W. Bott, Synthesis and reactions of the silicon-carbon bond, Organo-metallic Compounds of the Croup IV Elements, ed. A. G. MacDiarmid, Vol. 1, Part 1. Marcel Dekker, New York (1968). 

The reaction of tetramethylsilane with fluorine led to the isolation of several, partially fluorine-substituted tetramethylsilanes (see Tables VII-IX), and preservation of over 80% of the silicon-carbon bonds in the initial, tetramethylsilane reactant. The stability of many of the partially fluorinated germanes and silanes (some are stable to over 100°C) is very surprising, for the possibility of elimination of hydrogen fluoride is obvious. Indeed, before the first reported synthesis (12) of... 

The same type of reaction has been used just recently by Sonnek and coworkers [17] to get access to di(meth)acrylate structures added to siloxanes via hydrolytically stable silicon-carbon bond formation. 2-Heptamethyltrisiloxanylbut-2-en-l,4-diylbismethacrylate is accordingly prepared in 90 % yield by hydrosilylation of the bismethacrylate of 2-butyne-l,4-diol. 

Our interest in silicon chemistry quite naturally led to a study of the hydrosilation reaction, the addition of the Si-H group across an olefin or an acetylene. This reaction is one of the most useful methods of making silicon-carbon bonds and is an important industrial process. Typically, homogeneous catalysts based on platinum, rhodium or ruthenium are used, and while very efficient, they are not recoverable(46). 

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 analytical control of this step is of special importance the alcaline saponification is performed at a relatively low pH in order to prevent cleavage of the silicon-carbon bond. The closer the electron-with-drawing carboxyl group is located to the Si-C-bond, the larger is the danger of scission. Therefore, for the B-silyl carboxylic acid derivatives the pH during saponification should not surpass 10.5 however, at this pH saponification of the methyl ester requires about 1 day, even at 60°C. For the -silyl derivatives, the pH of the reaction mixture is not critical. We therefore now exclusively utilize the latter. 

Organic groups were detected on the surface after grinding of silica in the presence of organic solvents. Silicon-carbon bonds are also formed by nucleophilic attack on the siloxane bonds with lithium organic compounds. This reaction is analogous to the dissolution of silica with alkali hydroxides. 

Therefore, surface modification strategies for the formation of direct silicon-carbon bonds require, first, a special pre-treatment of the silicon surface to prevent oxidation and, second, an activation of the silicon surface for subsequent reaction with organic moieties. This has been achieved by treatment of the silicon surface with hydrofluoric acid to generate a hydrogen-terminated Si(lll) surface, which can further react with unsaturated co-functionahzed alkenes in the presence of UV irradiation or by thermal activation [27,44,45]. Using this method, carboxylic acid modified silicon substrates have been successfully generated and coupled to thiol modified ONDs via a polylysine/sulfosuccinimidyl 4-(M-maleimidomethyl)-cyclohexane-l-carboxylate couphng (Fig. 12). 

It appears that these reactions all may be explained by invoking a common intermediate phenylsilyl anion (VI) formed from the initial radical anion by reductive cleavage of a silicon-hydrogen or silicon-carbon bond ... 

Quayum, M. E., Kondo, T., Nihonyanagi, S., Miyamoto, D. and Uosaki, K. Formation of organic monolayer on a hydrogen terminated Si(l 11) surface via silicon-carbon bond monitored by ATR FT-IR and SFG spectroscopy Effect of orientational order on the reaction rate. Chemistry Letters, 208 (2002). 

In 1982, Curtis and co-workers reported that Vaska s complex promotes the formation of phenylsiloxanes from the reaction of hydridosiloxanes and benzene in a catalytic, albeit low-yield, process.93 Catalytic arylsilane formation has also been reported by Tanaka and co-workers. Under photo-lytic conditions, RhCl(CO)(PMe3)2 catalyzes the C-H bond activation of arenes in reactions with hydrosilanes or disilanes, leading to the formation of new silicon-carbon bonds.94 More recently, C-H bond activation of arenes resulting in arylsilane formation has been observed in the... 

Reaction with Further Electrophiles of Group IVA (Sl,Ge,Sn). IV-Silylated aziridines can be prepared from ethyleneimine by amination of chlorosilanes in the presence of an HC1 acceptor, by dehydrocondensation with an organosilicon hydride or by cleavage of a silicon—carbon bond in 2-furyl-, 2-thienyl-, benzyl-, or allylsilanes in the presence of an alkali metal catalyst (262—266). N-Silylated aziridines can react with carboxylic anhydrides to give acylated aziridines, eg, A/-acetylaziridine [460-07-1] in high yields (267). At high temperatures, A/-silylaziridines can be dimerized to piperazines (268). Aldehydes can be inserted... 

The pattern of results suggest that, if the substituent at the acyl group is alkyl, and hence relatively carbanion-destabilizing, rearrangement is inhibited relative to the alternative normal Wittig reaction pathway when the substituent is aromatic, however, and therefore capable of stabilizing incipient carbanion formation as the silicon-carbon bond... 

The reaction of methylenecyclopropanes with transition metal complexes is well known to promote a catalytic a-ir cycloaddition reaction with unsaturated compounds, in which a trimethylenemethane complex might exist71-76. Recently, much interest has been focused on the interaction of strained silicon-carbon bonds with transition metal complexes. In particular, the reaction of siliranes with acetylene in the presence of transition metal catalysts was extensively investigated by Seyferth s and Ishikawa s groups77-79. In the course of our studies on alkylidenesilirane, we found that palladium catalyzed reaction of Z-79 and E-79 with unsaturated compounds displayed ring expansion reaction modes that depend on the (Z) and (E) regiochemistry of 79 as well as the... 

When disilane, SizHg, is used in this reaction, the Si-H linkage is broken in preference to the Si-Si bond (165). Silicon-carbon bonds are not usually susceptible to cleavage, although Si-alkynyl bonds provide an exception (entry 47). If both Si-H and Si-alkynyl bonds are present, however, it is the former that cleaves (entry 56). The special case of metal insertion into Si-C bonds of strained heterocycles is dealt with separately in Section II,G,2, while an isolated but interesting example of Si-Hg bond cleavage appears in entry 36. 

The basic skeleton o7 tEe modified sorbents consists of a surface-active silica gel. Modification is in the form of a surface reaction with specially active silanes at the silanol groups of the silica gel. Following elimination of these silanol groups, new siloxane groupings are formed, on which aliphatic hydrocarbon groups are chemically bound by silicon-carbon bonds to the silica gel skeleton. Pre-coated plates with these modified silica gels are designated ... 

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