Organochlorosilanes

In reverse-phase chromatography, which is the more commonly encountered form of HPLC, the stationary phase is nonpolar and the mobile phase is polar. The most common nonpolar stationary phases use an organochlorosilane for which the R group is an -octyl (Cg) or -octyldecyl (Cig) hydrocarbon chain. Most reverse-phase separations are carried out using a buffered aqueous solution as a polar mobile phase. Because the silica substrate is subject to hydrolysis in basic solutions, the pH of the mobile phase must be less than 7.5. 

A convenient synthesis of organochlorosilanes from organosilanes is achieved by reaction with inorganic chlorides of Hg, Pt, V, Cr, Mo, Pd, Se, Bi, Fe, Sn, Cu, and even C. The last compounds, tin tetrachloride, copper(II) chloride, and, under catalytic conditions, carbon tetrachloride (117,118), are most widely used. 

Organochlorosilanes containing Si—H disproportionate in the presence of aluminum chloride without addition of more organosilane. Organic groups can be replaced by hydrogen (157). For example, tetraphenylsdane [1048-08-4] can be made from phenylmethylsilane [766-08-5]. 

Recently, the use of chemically bonded phases has become of great interest. In the typical case an organochlorosilane is reacted with dry porous silica to produce a surface that consists of an organic matrix (10). 

Figure 4.3 Synthesis of onoaeric and polymeric siloxane bonded phases by reaction of organochlorosilanes with silica gel under different conditions.

The cost of this work was defrayed in part from Grant-in-Aid for Special Project Research, Organic Chemical Resources, 61111002, to which the authors thanks are due. We also express our appreciation to Shin-etsu Chemical Co., Ltd., and Toshiba Silicone Co., Ltd., for a gift of organochlorosilanes. 

Organosilanols are important intermediates in the synthesis of silicones [5]. Among the different approaches to these species [5], the most convenient is the hydrolysis of organochlorosilanes. This reaction can be transfered to ferrio-chlorosilanes, e. g. la-c, which give the corresponding ferrio-silanols 2a-c in high yield, provided an auxiliary base is present (Eq. (1)). 

The example of the first category is the formation of alkyl- and arylchlorosilanes in the so-called direct process (DP). The process was discovered over 60 years ago by Rochow in the United States, and, independently, by Muller in Germany, and it is still the most important reaction in organosilicon chemistry. In fact, it is at the very basis of the silicone industry, being the primary source of organochlorosilane precursors (mostly methylchlorosilanes, comprising over 90% of the total) in the production of silicone oligomers and polymers. 

The most widely used support substance for the manufacture of packing materials in analytical HPLC columns is silica. Silica can be treated with organochlorosilanes or similar reagents to produce siloxane linkages of any derived polarity similar to what is done for GC columns (stationary phases). The most popular materials are octadecyl silane (ODS), which contains a carbon loading of CIS groups and octyl, which contains C8 groups materials such C2, C6, and C22 are also available. 

A second synthetic procedure for preparing silylated arene complexes, based on the metalation of a preformed rj6-arene complex, followed by treatment with an organochlorosilane, has been used only in one case so far namely, bis(benzene)chromium (47) ... 

Silicones are made by hydrolysis of organochlorosilanes RnSiCl4-n, which are produced from elemental silicon (obtainable from the carbon reduction of silica, i.e., sand, Section 17.7) by the Rochow process ... 

Independently, we reported [17] that the surfactant template can be directly exchanged by organochlorosilanes, which form a strong covalent bonding with the silica surface. A major advantage of this approach in comparison to the ion-exchange method [20] lies in its... 

First preparations were made by Schlenk eta/.546 who synthesized Si2 6 by the reaction of Siip3Cl with sodium. Kipping381 prepared the first mixed-substituent disilanes by reaction of the corresponding organochlorosilanes with sodium, but was not able to separate the optical isomers. Kraus and Nelson391 obtained Si2 et6 by this method. 

The synthesis of silicone polymers from prepolymers will allow one to obtain not only polyorganosiloxanes, but also polyelementorganosiloxanes of a more regular structure (unlike the existing processes of hydrolytic cocondensation of various organochlorosilanes which form polymers of a static composition). Therefore, the polymers obtained in this way will have improved chemical and physicochemical properties, and materials based on them will have valuable performance characteristics. Moreover, a new technique for obtaining polymers based on block oligomers will help to... 

Monomer silicone compounds, especially organochlorosilanes, hydroxyor-ganosilanes, alkylalkoxysilanes with amide groups in the alkyl radical, and acyloxyorganosilanes, have recently found an independent practical application, but their role as parent substances for the production of silicone oligomers and polymers is particularly important. 

There are a number of techniques to prepare organochlorosilanes the most widespread are the following ... 

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