Gas-phase reaction between hexamethyldisilane and iodine

Abstract

The gas-phase reaction between hexamethyldisilane and iodine between 458 and 523 K is first-order in hexamethyldisilane and one-half order in iodine and gives trimethylsilyl iodide as the only product. The reaction goes to completion, trimethylsilyl iodide being thermally stable. Arrhenius parameters, based on measurements during the first 10 % of reaction, are given by log k= 13.06 ± 0.50 – 109 ± 4.5/(2.303 RT), where k is in cm mol^–½ s^–1 and the activation energy is in kJ mol^–1. A simple chain reaction sequence is proposed, from which the Arrhenius parameters for the novel radical displacement reaction, I·+ Me₃SiSiMe₃→ Me₃SiI + Me₃Si·, are given by log k= 11.23 ± 0.50 – 33.8 ± 4.5/(2.303 RT), where k is in cm³ mol^–1 s^–1 and the activation energy is in kJ mol^–1.