The pyrolysis of propylene

Detailed analyses of the reaction products of the pyrolysis carried out in the temperature range 555 to 640°C, at initial pressures between 7 and 300 mmHg, and measurements of overall pressure change have shown that the overall pyrolysis may be described by the expression -d[C3H6]/dt = 1014.06[C3H6]1.4 exp (-58600/RT) mole ml.-1 s-1. Twenty three primary and three secondary products of the pyrolysis at 600°C and an initial pressure of 103 mmHg have been determined at six extents of reaction up to 12%. On the basis of these measurements a long chain free radical mechanism is proposed in which reactions of the 1-methyl-4-pentenyl radical are of prime importance. The main chain termination reaction is found to be combination of methyl and allyl radicals. It is concluded that radical combination reactions involving allyl are considerably slower than those involving alkyls. Steady-state treatment of the data is precluded by their complexity. Speculative routes to the formation of the many higher products are suggested.