The thermal reaction between tetramethylsilane and oxygen in the gas phase.

A review of the literature on the oxidation of hydrocarbons and organosilicon compounds with a particular emphasis on gas phase studies is presented. A comprehensive explanation of the experimental technique involved in the study of the oxidation of tetramethylsilane (TMS) in the gas phase is listed, with particular reference to the workings of the Q801 quadrupole mass spectrometer. The use of computational methods in routine data analysis is explained, and the various methods of numerical integration of a set of first order differential equations are discussed with particular reference to that of Gear's method, and an application of this package applied to chemical kinetics. Evidence is provided for the existence of dimethylsilanone in this reaction and how it reacts with the other species that occur within this reaction. The following short-lived silicon species were also observed:- Me3SiO., Me2Si(OH)2, Me3SiOH, with indirect evidence for Me3SiCH2 and Me2Si=CH2. The three stable silicon products observed were hexamethyldisiloxane, hexamethylcyclotrisiloxane, and octamethyl-cyclotetrasiloxane. The total order of the reaction although it tended to vary was about 2 1/2 this being proportioned as 3/2 and unity for TMS and oxygen respectively. The stoichiometry of the reaction (again a variable quantity) was about 1:2 TMS: oxygen. The temperature dependence studies were very widespread in their results but there is evidence of a region of 'high' and 'low' activation energy region on the Arrhenius plot for the disappearance of TMS. A mechanism is postulated for the oxidation of TMS based on an analogy with other oxidation studies and by refinement using computational means. This mechanism is not exact, but it describes the broad features that were observed experimentally.