Strahlungschemie von Kohlenwasserstoffen. 15. Mitteilung. Energieübertragung im System Benzol–3‐Phenylcyclohexadien‐(1,4)

Abstract

Abstract3‐Phenylcyclohexa‐1,4‐diene, which is a reaction product in the benzene radiolysis, is decomposed when its solutions in benzene are irradiated by γ‐rays. The main products are biphenyl (20%) and dihydrobenzene (10%). They show that hydrogen from phenylcyclohexadiene is transferred to benzene. The high G‐value for the disappearance is explained by energy‐transfer from a high‐lying state of benzene, formed with g(B*) ≥ 2, to the diene. From the concentration dependence in the range 0.015–0.25 Mol/1 can be concluded that τ · ktA is 21 1/Mole for phenylcyclohexadiene and 4 1/mole for cyclohexene, where τ is the lifetime of the excited state of benzene involved in the reaction and ktA is the rate constant for energy‐transfer from this excited state to the acceptor. This rate constant is in the same order of magnitude for biphenyl, naphthalene and cyclohexa‐1,4‐diene as accepted for phenylcyclohexadiene. The nature of the energy transfer from benzene to phenylcyclohexadiene is discussed. The possibilities of charge transfer or the lowest singlet‐ or tripletstate as excited states are ruled out.