COMPARISON OF THE CLEAVAGE REACTIONS OF ALPHA-NITROCUMENE RADICAL-ANION AND ALPHA,P-DINITROCUMENE RADICAL-ANION

The rates of loss of NO2- from the radical anions of 2-(4-nitrophenyl)-2-nitropropane (alpha,p-dinitrocumene) and 2-phenyl-2-nitropropane (alpha-nitrocumene) were compared by three different methods. The rate constant for the apparently heterolytic process (D(N)) undergone by the radical anion of the dinitrocumene was measured by pulse radiolysis to be 2 x 10(3) s-1 in dimethylformamide at 25-degrees-C. This value is in reasonable agreement with values estimated from an indirect chemical method and from cyclic voltammetry at low temperature. The rate for the formally homolytic dissociation process (D(R)) undergone by the radical anion of the mononitrocumene could not be determined by pulse radiolysis but could be shown to be between 50 and 1000 times faster than the dinitro case using the other two methods. Possible reasons for the faster rate for the D(R) process are discussed with reference to related systems for which the D(R) process had been found to be unexpectedly slow.