Nitrotoluenes, manufacture

Economic Aspects. Annual 1993 U.S. production of the mononitrotoluenes is 26,000 metric tons, with about 16,120 metric tons of the ortho isomer, 780 metric tons of the meta isomer, and 9,100 metric tons of the para isomer. The prices of (9-, m-., and -nitrotoluene in bulk fob are 1.15/kg, 2.54/kg, and 3.64/kg, respectively. The mononitrotoluenes are manufactured by Du Pont and First Chemical Corp. 

Catalytic hydtogenation is the most efficient method for the large scale manufacture of many aromatic and ahphatic amines. Some of the commercially important amines produced by catalytic hydrogenation include aniline (from nitrobenzene), 1,6-hexanediamine (from adiponitrile), isophoronediamine (from 3-nitro-l,5,5-trimethylcyclohexanecarbonitrile), phenylenediamine (from dinitrobenzene), toluenediamine (from dinitrotoluene), toluidine (from nitrotoluene), and xyhdine (from nitroxylene). As these examples suggest, aromatic amines ate usually made by hydrogenating the... 

Basic Explosives Manufacture. The major quantities and the toughest problems are here. They include a) acid waters, treated with lime or soda ash, chemical washes, spills, washdowns b) Red Water from TNT purification. A complex, brick-red soln of Na nitrate, Na sulfate, Na sulfite, Na nitrite, and about 17% organics which include sulfonated nitrotoluene isomers and complex, unidentified dye-bodies c) dissolved expls, eg, Pink Water which is approx lOOppm TNT in w d) suspended expl particles — dust and chips and e) sometimes solvents such as acet, benz, and dimethyl aniline... 

DAS (11.7) is synthesised from 4-nitrotoluene-2-sulphonic acid (11.6) by the route outlined in Scheme 11.1. An important factor in the preparation of DAST brighteners in the purity necessary for good performance is the purity of the DAS used as starting material. At one time DAS made in this way contained significant amounts of yellow azoxy compounds similar to 11.8, which formed the main components of the obsolescent dye Sun Yellow (Cl Direct Yellow 11) made by the partial reduction and self-condensation of intermediate 11.6. Today the major manufacturers supply DAS essentially free from these undesirable impurities [37]. 

A few triphenylmethane dyes are still obtained by empirical methods first used in the early processes of dye manufacture. For example, in the production of magenta (Cl Basic Violet 14), a mixture of aniline, toluidines and nitrotoluenes is heated with zinc and iron(II)... 

Nitrobenzene and nitrotoluenes that are manufactured are converted to aniline, isocyanates, and other products used in the production of dyes and pharmaceuticals. 

For TNT manufacture the presence of m- nitrotoluene in mononitrotoluene is naturally undesirable, as it is a source of unsymmetrical trinitrotoluenes. 

A commonly used method of obtaining TNT is the direct nitrating of a mixture of the three isomers of nitrotoluene. Details are given later (Chapter IX) in the description of the manufacture of DNT and TNT. The purification of TNT from unsymmetrical derivatives of m- nitrotoluene consists as a rule in the sulphitation of di- or, more often, tri-nitrotoluenes or in crystallization of the trinitro-products. 

Recently, as the disposal of large volumes of toxic waste waters from the purification of TNT by sulphitation has. become a problem (p. 390), new ways are being sought for the manufacture of TNT free from the unsymmetrical isomers. Apart from the possibility, mentioned above, of the utilization of nitrotoluene obtained by nitrating toluene with a mixture of acetic anhydride and nitric acid, factories TNT are now tending to separate nitrotoluene isomers by methods similar to those applied in the manufacture of dyestuffs intermediates. 

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... 

Nitrotoluene is of importance as an intermediate or precursor for in the manufacture of TNT. There are three isomers, of which only the ortho-and para-isomers can yield pure 2,4,6-trinitrotoluene. Mononitration of toluene yields mostly the orthocompound, as well as 4% of the meta-, and about 33% of the para-compound. 

Tedmical Observations. The manufacture of benzidine is one of the most important operations of dye chemistry, because this base is used in the preparation of numerous valuable, although generalty unstable, direct dyes. Similar methods are used to prepare the tolidines (ortho and meta) from o- and m-nitrotoluenes, and o-dianisidine from o-nitroanisole. Dyes from m-tolidine will rare go on cotton, but they are interesting wool dyes. 

A modification of the sulphuric acid process has been patented (1) when applied to a mixture of mono-nitrotoluenes and paraffin hydrocarbons. The nitration of the toluene is carried on carefuUy so as to take it only as far as the mononitrotoluene. The mono-nitrotoluene is dissolved in sulphuric acid, but any paraflShs that may be present will not dissolve, and will form a separate layer. A separation of these two layers and the subsequent nitration of the sulphuric acid solution of mononitrotoluene yields a very high grade TNT. Thus a toluene containing a comparatively large percentage of paraffins may be utilized in the manufacture of TNT. 

The Omega Nitrotoluenes (Phenylnitromethanes). Under v arious circumstances in the regulation manufacture of TNT a side-chain nitrated compoimd is... 

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,... 

Formation of nitrotoluenes is an important step in the manufacture of the trinitro product and has been the subject of some review articles [19, 20[ which were dedicated to the kinetics of mononitration. 

TDI (10a and 10b) is prepared from o-nitrotoluene, which is first nitrated to afford 1,4- and 1,5- dinitro isomers. These products are hydrogenated to the corresponding diamines, at 74 °C, over a palladium-on-carbon catalyst. This is the only major use of toluene diamines. On phosgenation, using chlorobenzene as solvent, at around 52 °C, the amines afford the diisocyanates. The TDI is used in the manufacture of flexible foams (upholstery, bedding, seat cushions, etc.), paints, surface coatings, elastomers and adhesives. 1,5-Diaminonaphthalene (13) is converted into naphthalene-1,5-diisocyanate (14) (Scheme 5), used in specialty polyurethanes. 

In an ironic aside, it is noted that the most recently suggested new use for phosgene is to "make safe" thousands of tons of TNT (2,4,6-trinitrotoluene) from redundant weapons, no longer required now that the Cold War has ended. Treatment of the TNT with ammonium sulfide would reduce it to 2,4-diamino-6-nitrotoluene, which could then be treated with phosgene to give 2,4-diisocyanato-6-nitrotoluene (NDTI), a potentially valuable precursor for polyurethane manufacture [64d]. Thus, instead of potentially hazardous, and certainly wasteful, destruction of the TNT, the use of phosgene could convert it into a valuable industrial commodity. 

Nitrotoluenes are intermediates for dyes, pharmaceuticals, and perfumes, and precursors for the explosive 2,4,6—trinitrotoluene (TNT). A mixture of o-and p-nitrotoluene can be nitrated to dinitrotoluenes, the feedstocks for the manufacture of diisocyanates. The isomeric 2,4— and 2,6-dinitrotoluenes are obtained in a ratio of roughly 80 20... 

Isomer control in the mononitration and dinitration of toluene was studied by Harris [23, 24]. Both papers were dedicated to the increase of p-nitrotoluene which is an important intermediate in dyestuffs and pharmaceuticals manufacture, where both < - and m-isomers are waste products and the high proportion of 2,4-dinitrotoluene is desirable for isocyanate production. This aim was achieved by adding phosphoric acid to the nitration mixtures. 

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