Rearrangement of aromatic N-nitroamines. Part VII. The acid-catalysed transformation of N-methyl-N-nitro-9-aminoanthracene

Abstract

Treatment of N-methyl-N-nitro-9-aminoanthracene with sulphuric acid (ca. 7N) yielded 10-nitroanthrone (90%) together with nitrous acid (5%). The reaction which involved intramolecular shift of the nitro-group, was first order in substrate its rate was linearly correlated with the h₀ function; but, unexpectedly, the reaction had a solvent isotope effect (k_D2O/k_H2O) of less than unity.

It is proposed that rate-limiting protonation of the aromatic ring and either direct migration of the nitro-group or migration via the intermediacy of a tightly-bound ion or radical pair occurred.

The present status of the ‘radical-pair’ and ‘cartwheel’ mechanisms for the nitroamine rearrangement is discussed.