Nitration with Neat 65 Nitric Acid

So far, in all experiments the nitrating agent was prepared by dissolving the appropriate amounts of 65% nitric acid in concentrated sulfuric acid. This is an additional process in the whole procedure. Therefore, it was decided to add the 65% nitric acid directly to the stream of the 1 m solution of4-(phenyl)morpholin- 

3- one in sulfuric acid. In this case the molar ratio of the nitrating species versus 

4- (phenyl)morpholin-3-one is around 10 1 and residence times longer than 

5 min would require rather long tubing. However, quantitative conversion could be brought about with low molarities and short residence times. Therefore, the residence time of the experimental plan was kept unchanged at 2.5 min (Table 15.6). 

Using this experimental plan only four experiments were necessary to prove a complete conversion. 

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Alkenes can react with nitric acid, either neat or in a chlorinated solvent, to give a mixture of compounds, including v/c-dinitroalkane, jS-nitro-nitrate ester, v/c-dinitrate ester, /3-nitroalcohol, and nitroalkeneproducts. Cyclohexene reacts with 70 % nitric acid to yield a mixture of 1,2-dinitrocyclohexane and 2-nitrocyclohexanol nitrate. Frankel and Klager investigated the reactions of several alkenes with 70 % nitric acid, but only in the case of 2-nitro-2-butene (1) was a product identified, namely, 2,2,3-trinitrobutane (2). 

The reaction of fuming nitric acid with 2-methyl-2-butene (3) is reported to yield 2-methyl-3-nitro-2-butene (4). The reaction of alkenes with fuming nitric acid, either neat or in chlorinated solvents, is an important route to unsaturated nitrosteroids, which assumedly arise from the dehydration of /3-nitroalcohols or the elimination of nitric acid from /3-nitro-nitrate esters. Temperature control in these reactions is important if an excess of oxidation by-products is to be avoided. 

Chemists at the Naval Air Warfare Center (NAWC), Weapons Division, China Lake, have reported many examples of polynitroarylamine synthesis via Bamberger rearrangements of arylnitramines. " " The nitration of 4-amino-2,5-dinitrotoluene (36) with a mixture of nitric acid and acetic anhydride in glacial acetic acid at room temperature yields the nitramine (37) which on treatment with neat sulfuric acid, provides 4-amino-2,3,5-trinitrotoluene (38) as the sole product. " Nitration of 3,4-dinitroaniline (39) with a solution of nitric acid in acetic anhydride yields A,3,4-trinitroaniline (40) acid-catalyzed rearrangement of the latter in neat sulfuric acid furnishes a 74 % yield of isomeric 2,3,4- (41) and 2,4,5- (42) trinitroanilines in a 4 6 ratio.Accordingly, a mixture of products can be expected when an unsymmetrical arylnitramine has two unsubstituted ortho positions available. 

To perform the organic nitration, the substrate 105 and solvent were brought together in a microstructure that afforded a fine emulsion this was followed by the addition of neat nitric acid 95 at which point the reaction started immediately. After the reaction had continued for the required time, it was stopped by the addition of water at a reduced temperature, prior to neutralization with NaOH. Neutralization was achieved in managed stages in order to control the release of heat into the reactor. Using this approach, a reactor volume of 150 ml allows the... 

Pyroxalam. The name given by Uchatius in the 1830 s to a white powder obtained by nitrating starch with a mixt of nitric and sulfuric acids, and which contained about 11.1% N. It was Nitrostarch (see in this Vol) with the formula C2 4H320l2(0N02)8, and closely resembled a product previously prepd (1832) by Braconnot by treating starch with neat coned nitric acid Ref Daniel (1902), 459, under Nitramidon... 

Nitrogen NMR data have been obtained using both the low-abundance, spin = 1/2 N and the predominant spin = 1 N nuclei. Several different references have been used for nitrogen NMR including aqueous ammonia, ammonium salts, acetonitrile, nitric acid, and nitrates. Current opinion favors neat nitromethane, and the compilation of the known data for 1,4-oxazines (Table 6) is expressed with respect to this reference and arranged in order of the observed chemical shift. For the C-labeled compound 87, carbamate rotamers lead to two separate signals and the value of 7c n can be determined -283.98 (d, J 9) and -284.46 (d, 7 11) <2001JOC8010>. 

Electron-releasing groups are required in the purine ring system before nitration can occur. In this way 8-nitro-caffeine (149), -theophylline (150), and -theobromine (151) have been prepared by nitration of the appropriate purine with nitric acid, neat or in acetic acid (71HC(24-2)i, p. 402). Similarly, 9-methylxanthine, but not xanthine, undergoes nitration to 9-methyl-8-nitroxanthine (60JA3773). 

For the next experiment a 1 m solution of 4-(phenyl)morpholin-3-one in acetic acid was treated with neat fuming nitric acid. Then the nitrating species was used in roughly 24-fold molar excess. Now (Table 15.3) the reaction proceeds much faster. 

Tablel5.6 Experimental plan forthe nitration of4-(phenyl)morpholin-3-one with neat 65% nitric acid. 

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