Gas-phase reactions of silicon-centred intermediates with chlorofluorocarbons

Article abstract of DOI:10.1016/0022-328X(96)06365-6

Pyrolysis of pentamethyldisilane in the presence of a CFC, dichlorodifluoromethane, efficiently replaced chlorine by hydrogen in the CFC, with concomitant formation of chlorosilanes. Although the primary intermediate in this pyrolysis is dimethylsilylene, there was strong evidence that conversions resulted from reactions of organosilyl and alkyl radicals. Experiments to confirm this conclusion are described, and mechanisms are discussed. Two independent measurements of the activation energy difference between chlorine-and fluorine-abstraction from dichlorodifluoromethane by trimethylsilyl radicals gave concordant values of 52 ± 5 kJ mol^-1. The reactions described are of interest in relation to the environmental importance of dechlorinating CFCs.