Pyrolysis of diallyl oxalate vapour. Part 2.—Sensitization by the ethyl radical

Abstract

The kinetics of the thermal decomposition of diallyl oxalate sensitized by the ethyl radical were studied in the gas phase between 115 and 160°C. Sensitization occurred by a sequence of the addition of the ethyl radical to diallyl oxalate followed by the dismutation of the adduct to yield the allyl radical, carbon dioxide, and pentene-1. Dismutation was the only significant reaction of the adduct, so that the rate of decomposition was equal to the rate of addition. Allyl radicals were consumed solely by cross interaction with the excess of ethyl radicals present and by mutual interaction. The pattern of cross interaction is given by the distribution of the products: C₅H₁₀(88±3)%, C₃H₆(9 ± 3)%, and C₃H₄(3 ± 1)%. The cross combination rate constant ratio for allyl and ethyl radicals is ϕ= 6.8 ± 0.9. The significance of these results is discussed.