The kinetics of the reactions of silicon compounds. Part II. The gas-phase thermal decomposition of 3,3,3-trifluoropropyltrifluorosilane

Abstract

The gas-phase thermal decomposition of 3,3,3-trifluoropropyltrifluorosilane proceeds by a complex radical-chain mechanism at temperatures from 550 to 640° and with initial pressures from 40 to 110 torr. The compounds SiF₄, C₂H₄, CHF₃, and CF₃·CH:CH₂ are major products; other primary products are H₂, CH₃·SiF₃, CH₂:CH·SiF₃, CH₂:CF₂, CF₃·CH₃, and a compound believed to be CF₂:CH·CH₂·SiF₃. The compounds CH₄, C₂H₆, and CF₃·CH₂·CH₃ were observed as secondary products. The decomposition is approximately of order 1·5 with respect to reactant in the initial stages, and the rate-constant is given by log₁₀k_1·5(cm. mole^–½ min.^–1)= 19·6 – 74 × 10³/4·58T. The results are interpreted in terms of a complex radical-chain mechanism.