Ene reactions of olefins, part II. The addition of ethylene to propylene and to isobutene and the addition of propylene to propylene

The pyrolysis of ethylene–propylene and ethylene–isobutene mixtures has been studied in a static system over the temperature range of 682°–754° K and for initial pressures of each olefin of 33–300 torr. The following molecular ene reactions were observed and the rate constants measured: equation image Using thermodynamic data, rate constants for the corresponding retro‐ene decomposition reactions were calculated and compared to kinetic data reported for similar compounds. Other products were formed by radical chain processes, the main higher molecular weight ones being cyclopentene and 1‐methylcyclopentene. A mechanism involving addition of allyl radicals is suggested for the formation of these products.