Gas phase reaction between iodine and tetramethylsilane. Part 1.—Equilibrium and thermochemistry

Abstract

The title reaction has been investigated in the temperature range 609–649 K. The principal products were trimethylsilylmethyl iodide and hydrogen iodide formed in equal quantities at equilibrium, viz., I₂+ Me₄Si ⇌ Me₃SiCH₂I + HI. Equilibrium constants were obtained over a limited range of reactant concentrations and in the presence of added HI. The temperature dependence of the equilibrium constants was investigated and thermodynamic parameters derived. At the mid temperature of the range, ΔG^°(629.4 K)=+ 27.8 kJ mol^–1. This result compares favourably with a group additivity estimate of + 26.7 kJ mol^–1 as well as the experimental value for ΔG^° for the analogous equilibrium reaction involving neopentane as reactant. There is no significant effect of Si for C substitution on the equilibrium investigated.