The effect of acid concentration on the pyridine nitramine rearrangement: an N.M.R. study

Abstract

The rearrangement of 2-and 4-nitraminopyridines in 70-95% sulfuric acid has been investigated by n.m.r. Ring nitration is favoured by conditions leading to initial dissociation of the nitramine, and the results provide no support for an intramolecular rearrangement mechanism.

2-Nitraminopyridines react to give the analogous pyridin-2-one at the low and, surprisingly, high ends of the concentration range. The 4-nitraminopyridine rearrangement is slower because of the greater basicity of pyridin-4-amine, and also because of the formation of an unidentified species which required heat to give the rearrangement product.