NMR-studien an chinonanilen. Der einfluss paraständiger substituenten im phenylring auf die thermische isomerisierung

Owing to isomerization at the CN double bond the NMR spectra of quinone aniles are temperature dependent. The free enthalpy of activation of the isomerization (ΔG^‡) is correlated to the Hammett σ_p-constants of the para substituents of the benzene ring: A large σ_p-value corresponds to a small ΔG^‡ value. This leads to the conclusion that the isomerization implies an inversion of the nitrogen atom.