The kinetics of the pyrolysis of propylene have been studied over the temperature range 743-873 "K and the pressure range 200-600 Torr. At the lower temperatures initiai rates of formation of methane, propane, and C , products were measured and shown to be formed by a radical process of very short chain length. The orders and activation energies of the rates were consistent mith the occurrence of the bimolecular initiation step 2C3Hcj -t C3Hs + C3H7 Measurement of the pressure change showed that products of ~nolecular weight higher than C, and not measured by the analysis were formed in the initial stages of the reaction at the lower temperatures. As these higher moleciilar weight compounds, ~~h i c h are m x e instable than propylene, acc~~mulated in the system their dissociation increased the concentration of radicals and caused a sharp increase in the rates of fornlation of the lower molecular weight stable products.
The selectivity of propane carbonylation in HF-SbF5 is found to depend on the propane/CO ratio, and is rationalized in terms of two competing activation processes for the alkane.
Carbonylation of propane in HF-SbF5 (5 : 1 molar ratio) superacid in the presence of carbon tetrachloride (or chloroform) at -30 "C yields exclusively the isobutyryl ion (isopropyloxocarbenium ion), analysis of the gaseous fluorocarbons generated as side products showing both hydride abstraction by CCI3+ (or CHC12+) and CI/F exchange on the tri-and di-chloromethane formed; in the absence of CCI4 (or CHC13) no reaction takes place under the same experimental conditions.
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