An EPR study of the radical addition to 3-nitropentan-2-one as an archetype of α-carbonylnitroalkanes.

Carbon, silicon, germanium, tin and lead-centered radicals were reacted with 3-nitropentan-2-one and 3-nitropentan-2-ol inside the cavity of an electron paramagnetic resonance spectrometer. In all cases, selective addition to the nitrogroup was observed with detection of the corresponding oxynitroxide radicals. In the case of the carbonyl substrate, alkyl acyl nitroxides were also detected because of α-photocleavage. The oxynitroxides decayed with a first order kinetics via fragmentation of the carbon-nitrogen bond (denitration). Unexpectedly, the activation parameters were fairly similar to those previously reported for the corresponding tert-butyl oxynitroxides and almost independent from the presence of a carbonyl or a hydroxyl group on the carbon adjacent to the one bearing the nitrogroup.