Gem-nitronitronate salts

The Ter Meer reaction has not been widely exploited for the synthesis of m-dinitroaliphatic compounds. This is partly because the Kaplan-Shechter oxidative nitration (Section 1.7) is more convenient, but also because of some more serious limitations. The first is the inability to synthesize internal em-dinitroaliphatic compounds functionality which shows high chemical stability and is found in many cyclic and caged energetic materials. Secondly, the em-nitronitronate salts formed in the Ter Meer reactions often need to be isolated to improve the yield and purity of the product. Dry em-nitronitronate salts are hazardous to handle and those from nitroalkanes like 1,1,4,4-tetranitrobutane are primary explosives which can explode even when wet. Even so, it is common to use conditions that lead to the precipitation of gem-nitronitronate salts from solution, a process that both drives the reaction to completion and also provides isolation and purification of the product salt by simple filtration. Purification of em-nitronitronate salts by filtration from the reaction liquors, followed by washing with methanol or ethanol to remove occluded impurities, has been used, although these salts should never be allowed to completely dry. 

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... 

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