Systems with Tetranitromethane as Nitrating Agent

Nitration with tetranitromethane proceeds along the ion-radical ronte. Tetranitromethane is a smooth nitrating agent and mild oxidizer. It is convenient for nitration of highly activated snbstrates snch as phenols, azulene, and heterocycles in the presence of pyridine, N,iV-dialkylaniline, etc. As shown (Morkovnik 1988), these reactions inclnde one-electron transfer  

The photochemical addition of tetranitromethane to aromatic compounds under conditions of excitation of the [ArH C(N02)4l charge-transfer complex by light matching the wavelength of the charge-transfer band results in a recombination within [ArH+, NOj, C(N02)3 ] triad. The destiny of triad depends on the nature of the solvent (Sankararaman et al. 1987, Sankararaman and Kochi 1991). In dissociating solvents, radical substitution is predominant, leading to nitro products and trinitromethane  

In nondissociating solvents, the main process consists of ion-pair reaction that results in the disengagement of nitrous acid and formation of trinitromethylated products  

The addition of a low amount of trifluoroacetic acid results in fast protonation of ClNOjls . The major follow-up reaction now becomes the slower reaction between ArH+ and NOj (Eberson et al. 1996). 

Studies of interactions between tetranitromethane and aryl derivatives of magnesium, tin, and mercury in sulfolane (Shevelyov et al. 1974, 1975) confirm that NO2 radical has some slight activity. For example, the reaction of diarylmercury with tetranitromethane passes through a transient step with the formation of radicals Ar and NO2. These radicals almost do not interact  

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