15N Nuclear polarisation in rearrangement of 2,6-dichloro-N-nitroaniline and 2,6-dibromo-N-nitroaniline

Article abstract of DOI:10.1139/v86-188

The acid-catalysed rearrangements of 2,6-dichloro-N-nitroaniline and 2,6-dibromo-N-nitroaniline to give the corresponding 4-nitro derivatives have been followed by 1H and 15N nmr spectroscopy in deuteriochloroform at 30 deg C.When 15NO2-labelled nitramines are used, the 15N nmr signals for both the substrate and product show enhanced absorption during reaction.When one labelled nitramine and one unlabelled nitramine rearranged together, isotopic exchange occurs and 15N nmr signals are seen for both substrates and both products.For the initially unlabelled nitramine and its product, these signals are in emission.The change in the enhancement of the signals during reaction shows that the nuclear polarization arises from the rearrangement, not from a preliminary equilibrium.