Preparation of dinitrotoluenes

The principal reaction products in the nitration of toluene are the isomers  

4- formed from o- and p- nitrotoluenes, and 2,6- formed from o- nitrotoluene. From m- nitrotoluene the 2.3-, 3,4- and 3,6-isomers are formed. The possibility of the formation of the 3,5-isomer in the direct nitration of m- nitrotoluene has not been definitely proved. 

Dinitrotoluene (2,4-) was first obtained by Beilstein andKuhlberg [21] in 1870. However, it may be that dinitrobenzene , m.p. 71°C obtained in 1841 by St. Claire Deville [25] by the nitration of nitrobenzene prepared from light oil, was in fact dinitrotoluene. As Rosensriel [26] found in 1872 p- nitrotoluene yields only one product of dinitration, viz. the 2,4-isomer, while o- nitrotoluene gives in addition another isomer, the structure of which he did not determine. 

The first indication of the existence of the other dinitrotoluene isomers can be found in the Limprichf s work [27]. He was able to isolate from the nitration products the 3,6-isomer, besides the 2,4- and 2,6-isomers. In 1903 Zaloziecki [28] nitrated the aromatic fraction of Galicia oil and isolated the 2,4- and 3,6-nitro-toluenes. 

The data were confirmed by Haussermann and Grell [29] in 1894. They stated that besides the isomers already mentioned, the 3,5-isomer was also isolated. Several authors questioned the presence of the latter isomer in the nitration products. For example, Sirks [30] reporttd that nitration of m- nitrotoluene resulted in the formation of the 3,4-, 2,3-, and 3,6-isomers, but not the 3,5-isomer. 

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Preparation of dinitrotoluenes Industrial methods of preparation of dinitrotoluenes Preparation of pure isomers a-Trinitrotoluene (TNT)... 

Low meta substitution allows favorable regiocontrol in the subsequent preparation of dinitrotoluenes. In general, the nitric add-trifluoro-methanesulfonic acid system shows less meta substitution than other nitrating systems at comparable temperatures (Table IV). The major factor, however, effecting low meia nitration is the use of extremely low temperatures. Solubility of the formed nitronium salt at low temperature in halomethane solutions is limited and unusual ortho/para ratios ma> be also a consequence of the heterogeneous nature of the reaction mixtures. 

The compound is prepared by the direct nitration of oxanilide (Mixter and Walther [40]). Domanski and Mieszkis [41] investigated the explosive properties of hexanitro-oxanilide and found the following values for the rate of detonation of the pressed product mixed with 2% of dinitrotoluene ... 

Cahours also prepared a dinitrotoluene, but unfortunately he did not leave any data as to which of the isomers he obtained. 

Preparation of mononitro toluenes Industrial methods of nitration of toluene Separation of isomers Distillation of crude nUrotx uene Crystallization of p-nitrotoluene Distillation of the mother liquor Continuous vacuum distillation of mononiirotoluene Preparation of pure isomers Dinitrotoluenes Physical properties Thermocbemical properties Chemical properties Toxicity... 

The research team of J.E. Baldwin developed the first synthetic sequence for the preparation of N(5)-ergolines. The key step was a hetero-Diels-Alder reaction of a substituted phenyl butadiene to form the piperidine ring. The phenyl butadiene substrate was prepared via the Meerwein aryiation of 1,4-butadiene and a diazonium salt derived from 2,6-dinitrotoluene. The initially formed chlorinated product was subjected to dehydrochlorination using DBU as the base. 

Hanwha Chemical Corp, built a full-scale SCWO plant for Namhae Chemical Corp, in Korea. The plant was commissioned in 2002 for treatment of wastewater from production of dinitrotoluene (DNT). Hanwha has constructed another SCWO plant for treatment of waste and wastewater from terephthalic acid (TPA) production. This plant was preparing for initial start-up in mid-2006. ... 

In a general synthetic method for the preparation of 127t-triheterapentalenes (73)-(76), cyclic thioureas or selenoureas are alkylated with 2,4-dinitrobenzyl chloride followed by neutralization with sodium carbonate. The resulting bases when treated with alkyl isothiocyanate or isose-lenocyanate, undergo elimination of 2,4-dinitrotoluene and concomitant addition of two molecules of the heterocumulenes to give the products shown in Scheme 20 <93AX(C)917>. 

Anhydrous Mixed Acid Systems. Although the initial experiments with nitrate salts produced quantitative yields of dinitrotoluene (DNT), there seemed to be no practical way to recycle acids or utilize the corresponding sulfate salt by-products. This consideration led us to try a mixed acid system that was equivalent to the salt mixtures In nltronlum Ion concentration. The mixed acid system was prepared essentially by dehydrating nitric acid with oleum and producing nltronlum blsulfate and sulfuric acid ... 

This reaction is useful for the preparation of Q-.a-dinitrotoluene derivatives. 

This method comes into consideration mainly for the preparation of suitable derivatives of mononitro compounds. Procedures are given on p. 124. It must be remembered that the introduction of a second nitro group can lead in certain cases to one dinitro compound from two isomeric mononitro compounds o- andp-nitrotoluene both give 2,4-dinitrotoluene on nitration. 

TNT (7.3) is produced by the nitration of toluene with mixed nitric and sulfuric acids in several steps. Toluene is hrst nitrated to mononitrotoluene and then dinitrotoluene and hnally crude trinitrotoluene. The trinitration step needs a high concentration of mixed acids with free SO3 groups. A summary for the preparation of trinitrotoluenes from toluene is presented in Reaction 7.3. 

Feng C, Shang H, Liu X (2014) Photocatalysis of dinitrotoluene decomposition by H3PWi204(/ri02 and H4SiWi204o/Ti02 prepared by a modified sol-gel synthesis and solvothermal treatment method. Chin J Catal 35 168-174... 

Dinitrotoluene can be prepared by the nitration of -nitrotoluene with yields of ca 96% or it can be obtained from the direct nitration of toluene. 

Nitrotoluene had been distilled under reduced pressure. The residue of the distillation detonated eight hours after its end. Amongst the possible causes mentioned was ttie accidental presence of a base in the medium. Another cause could have been the presence of a quantity of 2,4-dinitrotoluene (byproduct of the preparation reaction of the distilled compound) that was larger than thought. 

More complex explosives incorporating amino groups have been prepared from the reaction of polynitroarylene halides with amine nucleophiles. Agrawal and co-workers have synthesized PADNT (107) from the reaction of 4-amino-2,6-dinitrotoluene (46) with picryl chloride (87) in methanol 4-amino-2,6-dinitrotoluene is synthesized from the reduction of... 

Amino -2,6 -dinitrotoluene Is of interest as the intermediate for one procedure for preparing the thennally-stable, insensitive expl 2,4,6-triaminotrinitrobenzene (TATB) (Ref 119). Tri-nitrophloroglucinol (TNPG, see Vol 8, P248-R), the metallic salts of which have been considered as expl initiators, can also be made from It (Ref y 4). The reactions are ... 

Dinitrotoluene, prepared by nitrating p-nitrotoluene, and free from m-nitrotoluene, should not melt below 64.5°C. It should contain not less than 96% of 2,4-dinitrotoluene.. 

The thickness of the imprinted polymer shell can be also tuned in the range 10—40 nm by changing the relative amounts of functionalised silica nanoparticles and polymer shell precursors. The resulting core-shell particles exhibit enhanced capacity of rebinding the TNT template over 2,4-dinitrotoluene in comparison to particles prepared by precipitation polymerisation. Nevertheless, this strategy, although leading to impressive results, cannot be easily applied to other templates and monomers. 

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