Nitration procedures

In the last few years several modifications to the traditional mixed acid nitration procedure have been reported. An adiabatic nitration process was developed for the production of nitrobenzene (9). This method eliminated the need to remove the heat of reaction by excessive cooling. The excess heat can be used in the sulfuric acid reconcentration step. An additional advantage of this method is the reduction in reaction times to 0.5—7.5 minutes. 

Hercules Continuous Process Kouba et al (Ref 60) describe a novel tubular nitration procedure and app by which toluene is nitrated in two stages to form trinitrotoluene. In the first stage of nitration according to this invention, toluene is partially nitrated to an average nitrogen content between about 14.5% and about 16.5%, and in the second stage of nitration partially nitrated toluene is further nitrated to form trinitrotoluene... 

Another nitration procedure uses ozone and nitrogen dioxide.11 With aromatic hydrocarbons and activated derivatives, this nitration is believed to involve the radical cation of the aromatic reactant. 

A very attractive method for the preparation of nitroalkenes, which is based on the reaction with NO, has been reported. Treatment of alkenes at ambient pressure of nitrogen monoxide (NO) at room temperature gives the corresponding nitroalkenes in fairly good yields along with P-nitroalcohols in a ratio of about 8 to 2. The nitroalcohol by-products are converted into the desired nitroalkenes by dehydration with acidic alumina in high total yield. This simple and convenient nitration procedure is applied successfully to the preparation of nitroalkenes derived from various terminal alkenes or styrenes (Eq. 2.27).53 This process is modified by the use of HY-zeolites instead of alumina. The lack of corrosiveness and the ability to regenerate and reuse the catalyst make this an attractive system (Eq. 2.28).54... 

Grasshoff and Wenck [29] have described a version of the Mohr-Knudsen silver nitrate procedure for the determination of the chlorinity of sea water. In this method, which overcomes the disadvantages of conventional burettes, use is made of a motor-driven piston burette of 20 ml capacity, which is sufficient for a chlorinity range of 0 - 45 per thousand. The accuracy is the same as for conventional titration. The apparatus is compact and portable. 

Anthraquinone-1-sulphonic acid is the traditional precursor of 1-aminoanthraquinone (6.8), the most important anthraquinone intermediate. Since it is expensive to eliminate mercury(II) ions from waste water, an alternative route via 1-nitroanthraquinone has been investigated. Nitration of anthraquinone gives, as well as the desired 1-nitro derivative, significant amounts of the 2-isomer together with 1,5- and 1,8-dinitroanthraquinones. Nevertheless, chemists at Sumitomo in Japan have optimised the nitration procedure with respect to both yield and purity of the 1-nitro compound. In particular, nitration is stopped when 80% of the anthraquinone has been substituted [5]. Nitration of anthraquinone derivatives is also of some significance. 

This procedure illustrates a general method for converting substituted pyrylium salts to nitrobenzene derivatives. The reaction has been the subject of several reviews. - The yields are generally high, and under these conditions only a single product is formed, in contrast to the nitration of 1,3,5-triphenyl-benzene. The preparation of 2,4,6-triphenylnitrobenzene from the corresponding pyrylium salt eliminates isomer separation problems, which are encountered when the direct nitration procedure is used. Also, labeled compounds can readily be prepared by this method. ... 

The nitro group does not undergo migration of the naphthalene ring during the usual nitration procedures. Therefore, mono- and polynitration of naphthalene is similar to low temperature sulfonation, The nitronaphthalenes and some of their physical properties arc listed in fable 2. Many of these compounds are not accessible by direct nitration of naphthalene but are made by indirect methods, e.g nitrite displacement of diazonium halide groups in the presence of a copper catalysts, decarboxylation of nitronaphtbalcnccar-boxylic acids, or deamination of nitronaphthalene amines. They are nsed in the manufacture of chemicals, dye intermediates, and colorants for plastics. 

Nitration of polycyclic aromatic compounds has also been well studied, e.g., 1-nitronaphthalene (92%), 4-nitrobiphenyl (49%), and 2-nitro-fluorene (7S>%). One unusual aspect is the nitration of acenaphthene to 2-nitroacenaphthene (41%) by the action of benzoyl nitrate, whereas the customary nitration procedure yields mainly 4-nitroacenaphthene. ... 

These observations were incorporated into the following nitration procedure, 5-Chloro-l,3-dimethy1-lH-pyrazole (133 g,... 

The temperature rise of an exothermic reaction is dependent on three factors the heat of the reaction, the heat capacity of the system, and the heat loss of the system The temperature rise of a reaction in a system with no heat loss, the adiabatic temperature rise ( N T), is dependent on the heat of the reaction and the heat capacity of the system, and independent of scale To determine the adiabatic temperature rise of this system, the CDMP/sulfuric acid solution, prewarmed to 30°C, was added all at once to a dewar flask containing the nitric acid/sulfuric acid solution which was also prewarmed to 30°C We observed a temperature rise of 17°C over a period of 4 minutes, with a temperature drop of 1 5°C over the next 4 minutes (Figure 3) We therefore estimated the AT to be about 18.5°C Since this temperature rise was, in theory, independent of scale, we could predict that the large scale nitration reaction would not rise to a temperature of exothermic activity Based on these results, we considered this revised nitration procedure to be safe upon scale up to the pilot plant ... 

At this point, we returned to the original nitration procedure (with 2 3 molar equivalents of sulfuric acid) to try to determine why the nitration was not safe upon scale up The AT for this original procedure could be calculated from the heat capacity (Cp) of the system and the heat of the reaction ( AH) by the equation Ah = Cp x AT. The heat capacity of nitric acid/sulfuric acid/ water systems are available ( 0 and found to be 678 cal/mole °C (assuming that the heat capacity of the CNP/CDMP component was negligible) Using the experimentally derived temperature rise, the heat of the nitration reaction was estimated to be ... 

The nitration procedures described in the 1980s, using 4 as the starting material and leading to p-tetranitrocalix[4]arene 180a have more... 

Shang, W.-C. Zheng, Y.-S. Huang, Z.-T. Synth. Commun. 1997, 3763 describe a nitrating procedure using KNO3 and AICI3 in MeCN at O C. Attempts to reproduce their results under the conditions described as well as a number of variations on these conditions have failed. 

Following the procedure propane diurea was prepared in different batches with an average yield of 26 to 29 % and subsequently converted to tetranitropropane diurea. The slow nitration procedure reported here has the advantage of a significant higher yield (79—84%) and excellent product... 

Both RDX and HMX are prepared by the first method. Reactant hexamethylenetetramine (hexamine, 4) may be directly nitrated with nitric add to produce a mixture of RDX and HMX (principally RDX) (Refe. 10,12). Another nitration procedure that employs nitric acid, ammonium nitrate, and acetic anhydride is used to prepare HMX (Refe. 11,17). 

Bloom, J.A., Fleischmann, M. and MeUor, J.M. (1987) Nitration procedures using electrogenerated reagents. Electrochimica Acta, 32, 785. 

The highly selective N- and 0-functionalisation of adamantane based on the nitration procedure at -78 °C has been found [17]. Because of the symmetrical nature and high stability of the carbon framework, adamantane is a good model compound for examining the behaviour of alkanes toward the Kyodai nitration. 

The application of the standard Kyodai nitration procedure for pyridine gives a mixture of 5- and 3, 5-nitropyridine in only 2-5% yield [34]. However, pyridine can be efficiently nitrated by N,0 in liquid sulphur dioxide to give 3-nitropyridine in 68% yield [35]. The role of sulphur dioxide in the process is evident from the following scheme [34] ... 

By far the most generally useful and most commonly used nitrating procedure involves the use of solutions of nitric acid in sulfuric acid, commonly referred to as mixed acid [11,12]. 

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