2-nitro-2-propyl radical

In the initially proposed mechanism, the intermediate 2-nitro-2-propyl radicals, Me2(N02)C, undergo two reactions with the more basic (nucleophilic) thiolates addition of thiolates leading to SRN1 products (Equation 10.20 in Scheme 10.32), and SET to yield the nitro anion and thiyl radicals (RS ), Equation 10.21, which combine to give disulfide. 

Scheme 10.32 Intermediacy of 2-nitro-2-propyl radicals in reactions between a-substituted 2-nitro-propanes and thiolate anions.

It is characteristic that the new entrant methyl group assumes the ortho position to the nitro group and thus a substitution occurs which is similar to nucleophilic attack. Recently it has been found by Jackson and Waters [72] that higher nitrated benzene derivatives such as m- dinitrobenzene, or 1,3,5-trinitrobenzene, become homolytic hydrogen acceptors at temperatures of 80-100°C especially in the presence of the 2-cyano-2-propyl radical, which is formed by thermal decomposition of a,a -azo-bis-isobutyronitrile... 

We examined the thermal decomposition of a number of nitramines in dilute solution and in the melt phase. The nitramines included acyclic dialkyl mononitramines, where the dialkyls were methyl, ethyl, propyl and isopropyl cyclic mononitramines (N-nitro-pipeiidine and N-nitropyrrolidine) and cycle multifunctional nitramines (N-dinitropiperazhe l,3-dinitro-l,3-diazacyclo-pentane l,3-dinitro-l,3-diazacycbhexane RDX and HMX). For all nitramines, the predominant condensed-phase product was the nitrosamine though the amount formed depending on the nitramine and the phase of the thermolysis. The common trigger in the decompositions was N-N02 ho mo lysis, but the fate of the resultant amine radical depended on the phase. In solution the radical was stabilized sufficiently so that it resisted further decomposition and, instead, reacted with NO to form nitrosamine. In vapor or condensed phase, the amine radical underwent further reaction therefore,... 

I > Br > Cl > F) is in agreement with the order of the leaving ability of halide ions and also supports an SET reaction mechanism [7]. The intermediacy of the radicals (2) in the chain process is demonstrated by radical trapping with norbornene in the course of the perfluo-roalkylation of 2-nitro-2-propyl carbanion with perfluorooctyl iodide (Scheme 2.33) [8]. 

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