Mannich bases nitration

Mannich bases derived from polynitroalkanes are usually unstable because of the facile reverse reaction leading to stabilized nitronate anions. The nitration of Mannich bases to nitramines enhances their stability by reducing the electron density on the amine nitrogen through delocalization with the nitro group. The nitration of Mannich bases has been exploited for the synthesis of numerous explosives, some containing both C-NO2 and N-NO2 functionality. Three such compounds, (163), (164) and (165), are illustrated below and others are discussed in Section 6.10. 

Nitrosation and nitration— The NH amino group of sec-ondary amidic Mannich ba< es, upon reaction with nitrous acid, gives the N-nitroso derivative, which may then decompose in an alkaline medium to give diazoalkanes. The nitration of Mannich bases of nitroalkanes has been studied. Nitrolysis of C—N bonds of the base is frequently... 

Decreased reaction times have also been reported with the use of ceric ammonium nitrate (CAN). In the reaction of acetophenone 58, aldehyde 59, and amine 60 to afford Mannich base 61, the reaction time was reduced from 42 h to 7 h and the yield improved from 30 to 98% in going from no CAN to 5 mol %. 

Manganese dioxide 21,166, 625a, 907, 982 22, 780 -, ring closures, oxidative, with - 23, 494 -(II) nitrate 22, 255 Mannich bases, transamination with amidines, cyclic 18, 482 suppl. 21... 

A large number of nitramine-based explosives have been synthesized via Mannich-type condensation reactions (Section 5.13.2). The amines generated from these reactions often have the powerful electron-withdrawing trinitromethyl or fluorodinitromethyl groups positioned on the carbon a to the amino group. This reduces amine basicity to an extent that A-nitration becomes facile. The energetic nitramines (17), (19) and (21) have been synthesized from the condensation of ethylenediamine with 2,2,2-trinitroethanol, 2-fluoro-2,2-dinitroethanol with ethanolamine, and 2-fluoro-2,2-dinitroethylamine with 2,2-dinitro-l,3-propanediol respectively, followed by A-nitration of the resulting amine bases (16), (18) and (20), respectively. 

Various 2-oxo compounds have been subjected to a variety of reactions. Alkylation and acylation result in the formation of 1,3-disubstituted products.Similarly the Mannich reaction with morpholine gives products such as the bis compound 107. Halogenation of the 0x0 compound 108 with bromine in acetic acid," or chlorine in acetic acid, ° or with sulfuryl chloride results in formation of the monohalo derivatives 109. The chlorine atom in 109 (R = Cl) can be removed by hydrogenation over palladium on charcoal. Nitration of the chloro compound 110 with a mixture of nitric and sulfuric acids provides the nitro derivative 111, which may be catalytically reduced to the amino compound 112. If the reduction is carried out in the presence of an aldehyde, the product is a substituted amino derivative (113). Alternatively the amine 112 can be condensed with an aldehyde and the resultant Schiff base reduced to give the product 113. 

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