Carbon—silicon bonds metal halides

Polymer Modification. The introduction of functional groups on polysilanes using the alkali metal coupling of dichlorosilanes is extremely difficult to achieve. Some polymers and copolymers with 2-(3-cyclohexenyl)ethyl substituents on silicon have been made, and these undergo hydrogen halide addition to the carbon—carbon double bond (94,98). 

A148. C. T. Mortimer, Reaction Heats and Bond Strengths. Pergamon, Oxford, 1962. 201 pp. Metal-carbon and metal-halide bonds are considered in Chapter 8, and bond strengths in silicon, phosphorus, and sulfur compounds in Chapter 10. 

Some reactions of trimethylchlorosilane are summarized in Fig. 4.4. Many of these involve nucleophilic attack at silicon in which chlorine is substituted by another group. Alkoxysilanes are obtained using metal alkoxides or alcohols in the presence of pyridine. If the latter reaction is carried out in a non-polar solvent such as light petroleum, pyridinium hydrochloride is precipitated and may be filtered off, leaving the alkoxysilane in solution. Hydrogen chloride cleaves carbon-oxygen bonds in alkoxysilanes (as it does in ethers also) to form an alkyl halide and a siloxane ... 

The reaction of heterocyclic lithium derivatives with organic halides to form a C-C bond has been discussed in Section 3.3.3.8.2. This cannot, however, be extended to aryl, alkenyl or heteroaryl halides in which the halogen is attached to an sp2 carbon. Such cross-coupling can be successfully achieved by nickel or palladium-catalyzed reaction of the unsaturated organohalide with a suitable heterocyclic metal derivative. The metal is usually zinc, magnesium, boron or tin occasionally lithium, mercury, copper, and silicon derivatives of thiophene have also found application in such reactions. In addition to this type, the Pd-catalyzed reaction of halogenated heterocycles with suitable alkenes and alkynes, usually referred to as the Heck reaction, is also discussed in this section. 

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