Nitration, of aromatic amines

Nitration. Direct nitration of aromatic amines with nitric acid is not a satisfactory method, because the amino group is susceptible to oxidation. The amino group can be protected by acetylation, and the acetylamino derivative is then used in the nitration step. Nitration of acetanilide in sulfuric acid yields the 4-nitro compound that is hydroly2ed to -rutroaruline [100-01-6]. 

Nitration of aromatic amines with urea nitrate in sulfuric acid is reported to yield the -nitro derivative exclusively (44). When the para position is blocked, the meta product is obtained in excellent yield. 

Nitrations of aromatic amines often involve the intermediate formation of N-nitramines, although these are rarely seen under the strongly acidic conditions of mixed acid nitration (Section 4.5). N,2,4,6-Tetranitro-N-methylaniline (tetryl) is an important secondary high explosive usually synthesized from the nitration of N,N-dimethylaniline or 2,4-dinitro-N-methylaniline. ° The synthesis of tetryl is discussed in Section 5.14. 

Several lesser known nitrating agents, which can find practical use on a laboratory scale are metal nitrates in the presence of acetic acid or acetic anhydride, described by Menke [2], tetranitromethane and hexanitroethane in an alkaline medium, used by Schmidt [3], Mid nitroguanidine in solution in sulphuric acid, used for the nitration of aromatic amines Mid phenols. 

Melhylaminc nitrate Teiramcthylammonium nitrate Guanidine nitrate Nitrates of aromatic amines Ammonium chlorate Ammonium perchlorate Crystal structure and physical properties Thermal decomposition and burning of A P Thermal decomposition of irradiated ammonium perchlorate Influence of pressure on burning of A P Density and critical diameter... 

A number of nitrates of aromatic amines were recently described [42]. No information on their explosive or burning properties is available. 

A useful reagent for the regioselective nitration of aromatic amines is urea nitrate in sulfuric acid. p-Nitroanilines are formed exclusively. When the para position is blocked, nitration occurs to give the m-nitroaniline derivative. ... 

It was shown [108] that the nitration of aromatic amines proceeds differently depending on their basicity. Amines of moderate to low basicity, such as bis(2-cyanoethyl)amine (pATa = 5.25J, bis(2,2,2-trinitroethyI)-amine (p/ a = 0.05) are nitrated by NO2 BF4 to the corresponding N-nitramines in acetonitrile or ethyl acetate in yields of 87-98%. The nitration of highly basic dialkylamines (pK = 8.70-11.15) is accompanied by the partial reduction of NO2 BF4 to nitrosonium tetrafluoroborate and the formation of nitrosamines, The content of nitrosamine in the reaction mixture increases with increase of the reaction temperature. Nitronium hexafluorosilicate proved to be a milder nitrating agent its application makes it possible to reduce greatly the formation of nitroso- derivatives. 

---