Dianion of naphthylamines or a case of deprotonation from aromatic ring carbon?

Abstract

Proton transfer reactions have been studied in aqueous solutions for 1-naphthylamine (1N), 2-naphthylamine (2N), N, N-dimethyl-1-naphthylamine (M1N) and N,N-dimethyl-2-naphthylamine (M2N) by both steady-state and time-resolved methods. In the presence of a large excess of alkali both M1N and M2N produce new absorption and emission bands. Similar behaviour has been observed for 1N and 2N under the same conditions. On the basis of the time-resolved studies, it is suggested that ring deprotonation occurs in the ground state at very high alkali concentrations while hydroxyl-ion-catalysed tautomeric interconversion between two monoanionic forms occurs in the excited state.