Pyrolysis of chloroethylsilanes.

The gas-phase thermal decompositions of 2-chloro- ethyldiethylchlorosilane has been investigated in a static system between 298° and 352°C at initial pressures of 6 - 50 mm. Hg. Use has been made of pressure measurements, gas chromatography and mass spectrometry to obtain kinetic data and establish the mechanism. The over-all reaction is: where ethylene and diethyldichlorosilane account for more than 99% of the reaction product. The Arrhenius equation is given by:- A mechanism involving some charge separation in the transition state has been proposed and results from other 2-chloroethylsilanes have been discussed in the light of this proposal. An analogous study has been carried out on 2-chloroethyltriethylsilane between 310 and 330°C. It has been shown that the reaction:- ClCH2CH2.SiEt3?CH2 = CH2 + EtSiCl accounts for more than 99% of the reaction with:- However, the reaction is extremely sensitive to surface. The dehydrochlorination of 1-chloroethyldiethyl-silane in a static system between 372° and 437°C at initial pressures of 8 - 40 mm. Hg has been investigated. The results have been correlated with dehydrohalogenations from other alkyl halides.