Sulfur—silicon bonds halogens

The silicon-halogen, silicon-oxygen, and silicon-sulfur bonds of the haiogenosil-anes, siiyl ethers, and siiyi thioethers are cleaved by reaction with LAH, AIH3, or DIBAH, and the corresponding siiyl hydrides are obtained [CGI, CG2]. Ultrasound activation can be applied [LG2] (Figure 5.9), Anionic pentacoordinated silicon compounds are reduced to hydrogenosilanes by LAH or DIBAH [BC6]. 

The chemistry of silacyclopentanes resembles closely that of acyclic alkylsilanes. Strong bases are needed to cleave the silicon-carbon bond, while electrophilic attack occurs readily with halogens and strong acids, e.g. sulfuric. In addition, aluminum chloride will induce polymerization of silacyclopentanes unless one of the groups on silicon is carbofunctional (Scheme 154) (67MI12000). If this is chloromethyl, then ring expansion occurs (Scheme 155). 

You have now seen how enols and enolates react with electrophiles based on hydrogen (deuterium), carbon, halogens, silicon, sulfur, and nitrogen. What remains to be seen is how new carbon-carbon bonds can be formed with alkyl halides and carbonyl compounds in their normal electrophilic mode. These reactions are the subject of Chapters 26-29. We must first look at the ways aromatic compounds react with electrophiles. You will see similarities with the behaviour of enols. 

B. By oxidation Carbon-Phosphorus Bond Carbon-Silicon Bond Carbon-Halogen Bond Oxygen-Oxygen Bond Sulfur-Sulfur Bond... 

Organic compounds Substances whose molecules contain one or more carbon atoms covalently bonded with another element (including hydrogen, nitrogen, oxygen, the halogens as well as phosphorus, silicon and sulfur). 

Often, most atoms are bonded to a single atom. This atom is called the central atom. Hydrogen and the halogens are very rarely, if ever, centr2d atoms. Carbon, silicon, nitrogen, phosphorus, oxygen, and sulfur are always good candidates, because they form more than one covalent... 

This review article contains "best" values of bond-dissociation energies at 298.15 K of hydrocarbons and their nitrogen, oxygen, sulfur, halogen, and silicon derivatives. There is also some limited data on inorganic molecules. 

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