Ionization of aniline and its N-methyl and N-phenyl substituted derivatives by (Free) electron transfer to n-butyl chloride parent radical cations

The electron transfer from aniline and its N-methyl as well as N-phenyl substituted derivatives (N-methylaniline, N,N-dimethylaniline, diphenylamine, triphenylamine) to parent solvent radical cations was studied by electron pulse radiolysis in n-butyl chloride solution. The ionization results in the case of aniline (ArNH2) and the secondary aromatic amines (Ar2NH, Ar(Me)NH) in the synchronous and direct formation of amine radical cations, as well as aminyl radicals, in comparable amounts. Subsequently, ArNH2 center dot+ deprotonates in a delayed reaction with the present nucleophile Cl-, and forms further ArNH center dot. In contrast, tertiary aromatic amines such as triphenylamine and dimethylaniline yield primarily the corresponding amine radical cations Ar3N center dot+ or Ar(Me-2)N center dot+, only. The persistent Ar3N center dot+ forms a charge transfer complex (dimer) with the parent amine molecule, whereas Ar(Me-2)N center dot+ deprotonates to carbon-centered radicals Ar(Me)NCH2 center dot.