Radiolysis of Cyclohexane—Cyclohexene-1-14C Solutions

Radiolysis of solutions of 1% cyclohexene-1-14C in cyclohexane with 60Co γ rays yields radioactive cyclohexane, bicyclohexyl, cyclohexylcyclohexene, and bicyclohexenyl. Measurements were made of the total yield of these products, their specific activity, the total yield of hydrogen, and also the yield of hydrogen from pure cyclohexane. It is shown by material and radioactive balance considerations based on a simplified free radical mechanism, together with some known kinetic data, that a major fraction of the decrease in the H2 yield relative to that in pure liquid cyclohexane can be accounted for in terms of the reactions of H atoms with cyclohexene and the resulting formation of the radioactive C6H11 and C6H9 radicals. Detailed analysis shows that the specific rate of addition of H atoms to cyclohexene is 41 times greater than the specific rate of abstraction by H atoms from cyclohexane, and that the molecular (unscavengeable) and free radical yields in the irradiation of pure cyclohexane are, respectively, 1.7 and 3.7 molecules/100 eV. The latter conclusion is in fair agreement with results obtained by a number of other workers, but is in sharp contrast with recent results of Dyne. A plausible explanation is suggested to reconcile the discrepancy between the two sets of results.