Nitration of nitronate salts

Nitronate salts and the tautomeric act-form of nitroalkanes, known as nitronic acids, are converted to gem-dinitro compounds on treatment with dinitrogen tetroxide. Novikov and co-workers synthesized phenyldinitromethane by treating phenylnitromethane with dinitrogen tetroxide in ether and later reported the synthesis of some substituted phenyltrinitromethanes from the direct nitration of the nitronate salts of phenylnitromethanes. 

Phenyltrinitromethanes are similarly obtained from the nitration of gem-nitronitronate salts with a solution of dinitrogen tetroxide in ether. 1,1,1-Trinitroethane (73) can be formed in this way from the potassium salt of 1,1-dinitroethane (24). Nitrolic acids, the products formed 

Mixed acid or anhydrous nitric acid has been used for the nitration of em-nitronitronate salts to the corresponding 1,1,1-trinitromethyl compounds. A convenient route to hexan-itroethane (75) involves treating the dipotassium salt of 1,1,2,2-tetranitroethane (74) with mixed acid the nitration proceeding via electrophilic addition of the nitronium cation to the bis-nitronitronate ion.  

Tetranitromethane is an electrophilic source of nitronium cation and has been used in alkaline solution for the nitration of 1,1-dinitropropane to 1,1,1-trinitropropane (32%), and for nitration of l-phenyl-3-nitropropane to l-phenyl-3,3-dinitropropane (32 %) and its further nitration to l-phenyl-3,3,3-trinitropropane (33%).  

Olsen and co-workers reported the nitration of secondary nitroalkanes to m-dinitro compounds with nitronium tetrafluoroborate in acetonitrile at 0 °C. Yields are lower compared to the Kaplan-Shechter reaction and significant amounts of pseudonitroles are formed, but this is possibly due to impure reagent. 

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