C-Brominated Carbosilanes

The use of pure bromine under irradiation by UV light has been shown to be rather ineffective in the photobromination of (Cl2Si—CH2)3- More effective is the use of 

or bromine activated by means of CI2 under UV irradiation. Under these conditions (C Si— 112)3 reacts in CCl solution to generate a CBr2 group. 

The bromination product is a white crystalline solid with mp. 86-97 °C which sublimes atTOO C/IO mm Hg. To some extent it undergoes an exchange reaction, forming a CClBr group. As expected, the first stage in this reaction is the formation of a compound with a CHBr group [64]. 

The formation of more extensively brominated derivatives of (Cl2Si—CH2)3 did not occur because incorporation of even one CBr2 group impeded the reaction course and only resulted in a rechlorination reaction. 

The bromination of (Cl3Si—CH2)2SiCl2 occurred in a fashion similar to that of 

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