Alkylsilane compounds

Early work on the macroscopic friction of SAM films was carried out by DePahna and others using a pin-on-disk type friction tester, and they observed a low friction coefficient [1,13] however, their frictional property containing a wear resistance was demonstrated under a limited condition. For example, the self-assembled octadecyltrichlorosilane monolayer revealed a good wear resistance at low load [14], but failed to lubricate at a normal load of 1.0 N due to wear [15]. To overcome the poor wear resistance of thin films, a dual-layer film was prepared by a combination of aminoalkylsilane and stearic acid, which improved the wear resistance of the SAM film [16]. In this work, the authors also proposed a defect-free double layer on a flat substrate by chemical adsorption of alkylsilane compound. 

Densification occurs as a result of condensation of reactive surface chemical groups on network particles that appear as a result of the shrinkage. In order to avoid this reaction, a treatment of the internal surface is then required to protect reactive surface groups such as Si-OH and thus prevent freezing-in of collapsed structures by condensation. In silica gels, the surface modification is commonly done through a chemical reaction with reactive alkylsilane compounds to form hydrolytically stable Si-R groups on the surface. 

Silanes react with alkyllithium compounds, forming various alkylsilanes. Complete substitution is generally favored however, less substituted products can be isolated by proper choice of solvent. AH four methylsHanes, vinylsHane [7291-09-1and divinylsilane [18142-56-8] have been isolated from the reaction of SiH and the appropriate alkyllithium compound with propyl ether as the solvent (35). MethylsHane and ethyldisHane [7528-37-2] have been obtained in a similar reaction (36). 

Organosilicon compounds are widely used in our daily life as oil, grease, rubbers, cosmetics, medicinal chemicals, etc. However, these compounds are not naturally occurring substances but artificially produced ones (for reviews of organosilicon chemistry, see [59-64]). Hydrosilylation reactions catalyzed by a transition-metal catalyst are one of the most powerful tools for the synthesis of organosilicon compounds. Reaction of an unsaturated C-C bond such as alkynes or alkenes with hydrosilane affords a vinyl- or alkylsilane, respectively (Scheme 16). 

The modification of bentonite with alkylsilanes improves the dispersing properties [991]. Incorporation of phosphonate-type compounds in bentonites for drilling mud permits the blockage of free calcium ions in the form of soluble and stable complexes and the preservation or restoration of the initial fluidity of the mud [1222]. The phosphonates also have dispersing and fluidizing effects on the mud. 

See Xenon difluoride Silicon-nitrogen compounds See related alkylsilanes... 

Measurements of the autoignition temperatures for several series of mono-, di-, tri-and tetra-alkylsilanes showed that the ease of oxidation decreases with increasing substitution. In this group of easily ignited or pyrophoric compounds, individually indexed compounds are ... 

ALKYLALUMINIUM DERIVATIVES, ALKYLBORANES, ALKYLHALOBORANES ALKYLHALOPHOSPHINES, ALKYLHALOSILANES, ALKYLMETALS ALKYLNON-METAL HYDRIDES, ALKYLPHOSPHINES, ALKYLSILANES ARYLMETALS, BORANES, CARBONYLMETALS, COMPLEX ACETYLIDES COMPLEX HYDRIDES, HALOACETYLENE DERIVATIVES HEXAMETHYLNITRATODIALUMINATE SALTS, METAL HYDRIDES NON-METAL HYDRIDES, ORGANOMETALLICS, PYROPHORIC ALLOYS PYROPHORIC CATALYSTS, PYROPHORIC IRON-SULFUR COMPOUNDS PYROPHORIC METALS... 

Molecular Volume-Kow Relationships Relationships between Kow and different volume parameters have been reported. Leo et al. [41] compare correlations with Bondi and with CPK volume for two classes of apolar molecules (1) alkanes and alkylsilanes, and (2) perhalogenated alkanes and aromatic and haloaromatic compounds. Further, these authors discuss analogous correlations for alkanols and alkylphenols. 

IR, UV and, most importantly, NMR spectroscopy have proven to be excellent tools for elucidation of the molecular and electronic structures of silyl anions. Whereas 13C NMR data of metalated alkylsilanes are quite rare, the wealth of 13C NMR data which are available for metalated arylsilanes allows one to draw important conclusions concerning the question of charge delocalization in these compounds (Table 2)36,47. 

Similarly to the low chemical reactivity of (simple) alkylsilanes devoid of functional groups, the electrochemical reactivity of simple alkylsilanes is quite low. Klingler and Kochi measured the oxidation potentials of tetraalkyl derivatives of group-14-metal compounds by using cyclic voltammetry3. These compounds exhibit an irreversible anodic peak in acetonitrile. The oxidation potential (7 p) decreases in the order of Si>Ge>Sn>Pb as illustrated in Table 1. This order is the same as that of the gas-phase ionization potentials (7p). The absence of steric effects on the correlation of Ev with 7p indicates that the electron transfer should take place by an outer-sphere mechanism. Since tetraalkylsilane has an extremely high oxidation potential (>2.5 V), it is generally difficult to oxidize such alkylsilanes anodically. 

Benzylsilanes and allylsilanes are easily oxidized anodically compared with alkylsilanes and arylsilanes. Benzylsilanes exhibit irreversible cyclic voltammetric waves. It is notable that their oxidation potentials (Ep) are markedly less positive than those of the unsilylated parent compounds owing to the a-jr interaction (Table 3)10a. It is interesting that a-trimethylsilylation of xylenes markedly decreases their oxidation potential while additional a -trimethylsilylation makes a little change (Table 3). It has also been reported that a a, a-interacting system (the neighboring C—Si bonds) in addition to a a-ir interaction caused a significant decrease of the oxidation potentials1013. 

This compound, which exists as the dimer, explodes on contact with water. See ALKYLALUMINIUM DERIVATIVES See related ALKYLSILANES... 

See Xenon difluoride Silicon—nitrogen compounds See related ALKYLSILANES... 

Momentary exposure of traces of the product on a stopper to air usually causes ignition. See other mercury COMPOUNDS See related ALKYLSILANES... 

It may decompose spontaneously if too high a distillation temperature is attained. See other N—O COMPOUNDS See related ALKYLSILANES... 

Many investigations of alkyl and aryl chlorosilanes have been reported (125, 220, 225, 254). The probability of cleavage of the R—Si bond is found to decrease with increase in the size of R (220). Methylsilanes (143) and hydrocarbons with trialkylsilyl groups (145) are discussed and extensive studies of linear and cyclic silicon-methylene compounds are also available (22-24, 105-107, 225). Russian workers have looked at alkylsilanes (68), silacycloalkanes (69), and silylvinylacetylenes (144, 195). Silicon-carbon... 

Addition of hydrosilane to alkenes, dienes and alkynes is called hydrosilylation, or hydrosilation, and is a commercially important process for the production of many organosilicon compounds. As related reactions, silylformylation of alkynes is treated in Section 7.1.2, and the reduction of carbonyl compounds to alcohols by hydrosilylation is treated in Section 10.2. Compared with other hydrometallations discussed so far, hydrosilylation is sluggish and proceeds satisfactorily only in the presence of catalysts [214], Chloroplatinic acid is the most active catalyst and the hydrosilylation of alkenes catalysed by E PtCU is operated commercially [215]. Colloidal Pt is said to be an active catalytic species. Even the internal alkenes 558 can be hydrosilylated in the presence of a Pt catalyst with concomitant isomerization of the double bond from an internal to a terminal position to give terminal silylalkanes 559. The oxidative addition of hydrosilane to form R Si—Pt—H 560 is the first step of the hydrosilylation, and insertion of alkenes to the Pt—H bond gives 561, and the alkylsilane 562 is obtained by reductive elimination. 

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