Mechanism of pyrolysis of methylchlorosilanes.

This work describes the kinetics and mechanisms of the gas phase pyrolyses of some methylchlorosilanes based on experimental and numerical integration studies. Chapter 1 introduces a brief summary of the general properties and chemistry of silicon intermediates: silylenes, silenes, disilenes and silyl radicals. Chapter 2 describes the Stirred Flow Reactor technique used for studying the gas phase pyrolyses of methylchlorosilanes. This chapter also describes numerical integration methods. Finally, a description of the experimental set up used for studying the photochemical interaction between C60 (Buckminsterfullerene) and silicon intermediates concludes this chapter. Chapters 3-7 describe gas phase pyrolyses of methylchlorosilanes complemented by numerical integration studies. It is shown in each case that thermal decomposition is initiated by a radical mechanism. Trapping experiments using toluene and buta-1,3-diene with methyldichlorosilane show formation of silyl and silylene intermediates. Kinetic experiments on methylchlorosilanes in the presence of CO2 show an increase in the rate of methane formation. Numerical integration studies show that the short lived double bonded intermediates CH2=SiX2 (X = H,Me and Cl) are important in the pyrolysis of some methylchlorosilanes. A significant finding of this work is that silylene insertion reactions play an important part in MexSiCly (x,y =1,2) pyrolyses. The findings of Chapter 3-7 are discussed together in Chapter 8. In the appendix an account of an attempted gas phase synthesis of polysilane attached to C60 (Buckminsterfullerene) is presented.