Tertiary nitro compounds radical anions

Aliphatic nitro compounds exhibit rather different behavior from nitroaromatic compounds. Secondary and primary nitro compounds tend to produce oximes because the intermediate nitroso compound quickly tautomerizes to the oxime (equation 1). Under aprotic conditions the radical anions of primary and secondary nitro compounds are relatively stable those derived from tertiary nitro compounds, on the other hand, eject nitrite ion relatively readily (equation 2)8. 

The alkyl nitrate nitration of 4-isopropyl pyridine which was expected to give the tertiary nitro compound took an entirely different course. Instead of the nitro compound there was formed the dimer, 2,3-dimethyl-2,3-di(4-pyridyl)butane in a yield of 80% (eq 21). It is very likely that the dimerization reaction proceeds by a radical anion pathway and that the nitro compound... 

Besides solvation, a solvent can also participate in entrainment of ion-radical transformations. The reaction between tertiary aliphatic nitro compounds and the sodium derivative of nitromethane, NaCH2N02, is an example (Kornblum and Erickson 1981). To prepare NaCHjNOj, nitromethane is treated with sodium hydride. Then a tertiary aliphatic nitro compound is introduced into the solution formed. Several organic solvents were probed and CHjSOjCHj (DMSO) turned out to be the most effective. Kornblum and Erickson (1981) attributed this result to the formation of small amounts of NaCH2SOCH3 (sodium dimsyl) that was produced from DMSO as a result of its reaction with sodium hydride. Sodium dimsyl acts as a powerful one-electron reducer that induces the following chain anion-radical process ... 

From tertiary aliphatic nitro compounds the N02-group can be reductively removed. By ESR and cyclic voltammetry a radical anion has been demonstrated to be the first intermediate (Eq. (235) )524 This dissociates to N02... 

The SrnI reaction also proceeds with tertiary benzyl nitro compounds lacking a p-nitro substituent. The nitro group at the benzyl position acts as the electron acceptor, and decomposes to the benzyl radical and nitrite anion. The nitronate anion nucleophiles are then alkylated. Entry 5 in Scheme 12.7 provides a specific example. 

This reaction also can be made to proceed with tertiary benzyl nitro compounds lacking the p-nitro substituent. The nitro substituent at the benzyl position provides sufficient stabilization to permit the electron transfer to proceed, generating the radical anion. This species decomposes to a tertiary benzyl radical by loss of nitrite ion. Substituted nitrocumyl systems can alkylate nitronate anions in HMPA sol-... 

The radical anions of acyclic and alicyclic nitro compounds have been investigated in aqueous media. They have been obtained for primary, secondary, and tertiary nitro derivatives ... 

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