The kinetics of the reactions of silicon compounds. Part V. Liquid-phase thermal decomposition of 2,2-difluoroethyltri-n-butoxysilane
Abstract
The liquid-phase thermal decomposition of 2,2-difluoroethyltri-n-butoxysilane into vinyl fluoride and tri-n-butoxyfluorosilane has been studied using the silicone fluid MS 550 as the inert solvent. An experimental method has been devised in which the reaction is followed by the vinyl fluoride evolved. At 230–266° the reaction is first-order over a six-fold range of initial concentration, homogeneous, and unaffected by the addition of tri-n-butoxyfluorosilane or trans-stilbene. The first-order rate constant is given by: log10k(sec.–1)=(8·53 ± 0·22)–(30·30 ± 0·53)/0·004576T The reaction is probably unimolecular, proceeding by a four-centre β-fluorine elimination as for the gas-phase decomposition. The transition state appears to be more heavily solvated than the reactant molecule, and may thus be polar in character.