Organosilicon compounds : XLI. A kinetic study of the gas-phase reaction between silicon hydrides and aryl chlorides

Abstract

A kinetic study has been made of the reaction between chlorobenzene and trichlorosilane in a static system at 380–575°. In the 380–430° region the reaction has an activation energy of only 6.4 kcal/mole, and is of first order in chlorobenzene and zero order in trichlorosilane, whereas at 470–575° it has an activation energy of 26.5 kcal/mole and is of first order in both reactants. Over the whole temperature range the reaction is substantially inhibited by nitric oxide, and the rate is effectively independent of the surface to volume ratio of the container. It is suggested that reaction is initiated by dissociation of the SiH bond at the surface, but that different modes of adsorption operate in the two distinct ranges. Radical chains are then propagated in the gas phase and terminated at the surface. The reactant pairs p-MeC 6H 4ClCl 3SiH, p-CF 3C 6H 4ClCl 3SiH, PhClMe 3SiH, PhClMeCl 2SiH, and PhClEt 3SiH have also been studied. In the low temperature range the hydrides Me 3SiH and MeCl 2SiH react with chlorobenzene at the same rate as trichlorosilane.