Fluorination of SiCl-Containing Carbosilanes

The compounds (Cl3Si—CH2)2SiCl2 and (ClaSi—CCl2)2SiCl2 can be fluorinated in chloroform, as well as in acetonitrile and dichlorotrifluoroethane with Znp2. The separation of the fluorinated products (p3Si— 

For the fluorination of (Cl3Si—CH2)2SiCl2, N = C—(CH2)4—C=N can also be employed as a solvent. In this case the fluorination proceeds so quickly that ice-cold water must be used to control the temperature of reaction. The speed of the dropwise addition of the diluted starting material had to be adjusted so as to maintain the temperature of the reaction mixture [90]. 

Investigations on (ClgSi—CCl2)2SiCl2 show that reaction with ZnF at 20 °C will produce (F3 Si—0012)2 SiF yield, while at 100 O molecular cleavage occurs 

The reaction of perchloro-l,3,5,7-tetrasilaadamantane with ZnF2 does not proceed to its fluorinated derivative. At 110 °C in a sealed tube, cleavage occurs along with the formation of SiF and an SiF-containing residue. No reaction occurs at lower temperatures. 

The formation of C-chlorinated SiF-containing cyclic carbosilanes is possible through reversal of the reaction pathway, namely, via photochlorination of the corresponding SiF-, CH-containing compounds (see Table 36) [89]. 

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