Nitration of Toluene with Mixed Acid

Bromine Trifluoride. Frozen toluene reacts violently with bromine trifluoride at -80°C.3 Dinitrogen Tetroxide. Mixture of toluene and the tetroxide is liable to explode.4 Nitric Acid and Sulfuric Acid. Inadequate control in nitration of toluene with mixed acids may lead to a runaway or explosive reaction.5... 

Trinitrotoluene was prepared by Wilbrand in 1863 by the nitration of toluene with mixed acid, and in 1870 by Beilstein and Kuhlberg by the nitration of o- and p-nitrotoluene, and by Tiemann by the nitration of 2,4-dinitrotoluene. In 1891 Haus-sermann with the Griesheim Chem. Fabrik undertook its manufacture on an industrial scale. After 1901 its use as a military explosive soon became general among the great nations. In the first World AVar all of them were using it,... 

Derivation Nitration of toluene with mixed acid. Small amounts of the 2,3,4- and 2,4,5-isomers are produced that may be removed by washing with aqueous sodium sulfite solution. 

Figure 2. Production of MNT b- HNOs during the nitration of toluene with mixed acid...

Nitration of toluene with mixed acid gives mixed nitrotoluenes, which are mainly o-nitrotoluene (about two thirds) and p-nitrotoluene (about one third) the pure chemicals can be obtained through separation. After toluene is added to a reactor and cooled to 25 °C, the previously mixed acids were added (25-30 % of nitric acid, 55-58 % of sulfuric acid and 20-21 % of water) and the temperature adjusted to less than 50 °C. After 1-2 h of stirring and then 6 h of static storage, the... 

Beilstein Kuhlberg investigated nitration of toluene with mixed nitric-sulfuric acid of various concns and isolated for the first time several isomers of mono- and dinitro-toluene. They also prepd in 1870 TNT, but did not prepare Trinitrobenzene. At about the same time, mono-, di-, tri- and tetra-nitronaphthalenes were prepd (Ref 12, p 18). Trinitrobenzenes were prepd in 1882 by P. Hepp... 

TNT (7.3) is produced by the nitration of toluene with mixed nitric and sulfuric acids in several steps. Toluene is first nitrated to mononitro-toluene and then dinitro toluene and finally crude trinitrotoluene. The trinitration step needs a high concentration of mixed acids with free S03... 

Displaying a grasp of chemistry remarkable even among chemical engineers, the authors ascribe the hazardous side reaction consequent upon mono-nitration of toluene in mixed acid, to a decomposition of nitric acid (science has hitherto regarded nitric acid as thermodynamically more stable than conceivable decomposition products). This is favoured by poor mixing in what they describe as a three phase mixture (m/xo-nitrotoluenes being apparently immiscible with toluene). What the calorimetric study described seems to have observed is the transition from nitration to oxidation of the substrate. 

Nitric Acid and Toluene. Nitration of toluene with mixed concentrated acids must be carefully controlled or an explosion can result.18... 

Normally, nitration of deactivated compounds (and therefore polynitration of toluene) is carried out using aggressive nitric acid - oleum mixtures. Dinitration of toluene with mixed acids produces a 4 1 ratio of 2,4- and 2,6-dinitrotoluenes, from which the former is isolated for manufacture of toluenediisocyanate (TDI) and toluenediamine, both of which are used in the manufacture of polyurethanes. Zirconium and hafnium derivatives catalyse nitration of o-nitrotoluene, but ratios of 2,4- 2,6-dinitrotoluene are modest (66 34).12 Dinitration of toluene using Claycop (copper nitrate on K10 clay), acetic anhydride and nitric acid in the presence of carbon tetrachloride produced dinitrotoluenes in a yield of 85% with a ratio of 2,4- 2,6-dinitrotoluene of 9 1.13 This method, however, requires a large excess of nitric acid, the use of an unacceptable solvent and long reaction times. The direct nitration of toluene to 2,4-dinitrotoluene using nitric acid over a zeolite P catalyst, with azeotropic removal of water, is reported to give a 2,4 2,6 ratio of 14, but full results are yet to be published.14... 

It is produced by nitration of toluene with mixed nitric and sulfuric acid in several steps. The trinitration step needs high concentrated mixed acids with free S03. There are batchwise and continous nitration methods. TNT for military use must be free from any isomer other than the 2,4,6 (the specifications). This can be done by recrystallization in organic solvents (alcohol benzene) or in 62% nitric acid. The non-symmetrical isomers can be destroyed by washing with an aqueous sodium sulfite solution this processing, however, brings about large quantities of red colored waste waters. 

The above mentioned disadvantages of PA are overcome by the introduction of trinitrotoluene (TNT). Pure 2,4,6-TNT was first prepared by Hepp (Fig. 1.3) and its structure was determined by Claus and Becker in 1883. In the early 20th century TNT almost completely replaced PA and became the standard explosive during WW I. TNT is produced by the nitration of toluene with mixed nitric and sulfuric acid. 

Aromatic hydrocarbons can be converted into nitro compounds via an electrophilic substitution using mixed acid. For example, trinitrotoluene is obtained by the direct nitration of toluene using mixed acid. Other good nitrating agents are N02 BF4 and N020S02CF3 (nitronium triflate) in CH2C12 with ultrasonic activation. 

It is prepared by the direct nitration of toluene with a mixture of nitric and sulphuric acids. TNT is a very stable, violent and powerful high explosive, but less sensitive to shock and friction than picric acid. It is widely used as a filling for shells, bombs, etc. often mixed with ammonium nitrate and other high explosives. The lower grades of TNT may contain isomers which under hot storage conditions may give rise to exudation. 

Prepn of all three of the isomers of nitro-toluene is usually by nitration of toluene with varying concns of mixed acid. However, Urbafiski (Ref 2, p 274) reports that a soln of... 

Red Water — which can be almost black at times - also contains dissolved TNT however, it is not an incidental stream like Pink Water it is a major by-product stream from TNT manuf. The mixed-acid nitration of toluene yields not only 2,4,6-trinitrotoluene, the desired product, but also a host of other isomers and by-products amounting to approx 4.5% of the total yield and it is necessary to remove them from the product. They are removed by extraction with a Na sulfite—Na carbonate soln which sulfonates and dissolves them the extract is called Red Water. Red Water is a very complex and somewhat variable mixt containing 15% or so of sulfonated or sellited nitrobodies and a number of inorganic salts. Typical components are w, NajSOj—NaS04, NaN02— NaNOj, sulfonated or... 

Liquid-liquid immiscible liquid phases reactions such as the nitration of toluene or benzene with mixed acids, and emulsion polymerisations. 

The presence of two methyl groups in m-xylene makes it a more reactive substrate than toluene, but as a consequence, this substrate is more susceptible to oxidation. Therefore, the nitration of m-xylene requires lower temperatures and the use of less concentrated mixed acid. In fact, the nitration of either 2,4- or 2,6-dinitro-m-xylenes to 2,4,6-trinitroxylene (TNX) can be achieved with mixed acid containing up to 10 % water. TNX is a less powerful explosive than TNT and has a poor oxygen balance (—78.4 %). 

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