EVIDENCE FROM N-15 NUCLEAR-POLARIZATION ON THE MECHANISM OF ADDITION OF NITROGEN-DIOXIDE TO ALKENES

Nitrogen dioxide reacts with 2-ethyl-1-butene and 2-methyl-2-pentene in n-hexane as solvent to give mainly the corresponding dinitro compounds and nitro alcohols (believed to be derived from nitronitrites during the separation process). When N-15-labelled nitrogen dioxide is used, the products show strong N-15 nuclear polarization: the signal from the first nitro group to be introduced into the alkene shows enhanced absorption and, in the dinitro compounds, the signal from the second nitro group is in emission. The results indicate that both the dinitro compounds and the nitronitrites are formed by the reaction of the alkenes with two successive nitrogen dioxide molecules. The results do not, however, exclude the possible contributions of other reaction paths.