Of dinitrotoluenes

Mixtures of HNO, H2SO4, and SO also result in high concentrations of NO/, and toluene can be readily nitrated at —40 to — 10°C as a result (6). At these low temperatures, the formation of the meta-isomer of mononitrotoluene (MNT) is greatiy reduced. Such a reduction is highly desired in the production both of dinitrotoluenes (DNTs) employed to produce intermediates for polyurethane production and of trinitrotoluene (TNT), which is a high explosive. > -MNT results in the production of undesired DNT and TNT isomers (see Nitrobenzene and nitrotoluenes). 

Manufacture and Processing. Mononitrotoluenes are produced by the nitration of toluene in a manner similar to that described for nitrobenzene. The presence of the methyl group on the aromatic ring faciUtates the nitration of toluene, as compared to that of benzene, and increases the ease of oxidation which results in undesirable by-products. Thus the nitration of toluene generally is carried out at lower temperatures than the nitration of benzene to minimize oxidative side reactions. Because toluene nitrates at a faster rate than benzene, the milder conditions also reduce the formation of dinitrotoluenes. Toluene is less soluble than benzene in the acid phase, thus vigorous agitation of the reaction mixture is necessary to maximize the interfacial area of the two phases and the mass transfer of the reactants. The rate of a typical industrial nitration can be modeled in terms of a fast reaction taking place in a zone in the aqueous phase adjacent to the interface where the reaction is diffusion controlled. 

Formation of diamines from dinitro compounds, which are unable to interact intramolecularly, presents no problem. Very large volumes of diaminotoluene, a precursor to toluene diisocyanate, are produced by hydrogenation of dinitrotoluene over either nickel or palladium-on-carbon. Selective hydrogenation of one or the other of two nitro groups is much more of a challenge, but a number of outstanding successes have been recorded. A case in point is the hydrogenation of 2,4-dinitroaniline (11) to 4-nitro-l,2-benzenediamine (12) (2) or to 2-nitro-l,4-benzenediamine (10). 

An alternative route for TDI is through a liquid-phase carhonylation of dinitrotoluene in presence of PdCl2 catalyst at approximately 250°C and 200 atmospheres ... 

The gas chromatographic determination of isomers of dinitrotoluene in seawater has been described by Flashimoto and co-workers [296,297]. These authors describe the complete separation of six dinitrotoluene isomers using gas chromatography with support-coated open tubular glass capillary columns and electron-capture detection. The method was applied to the qualitative and quantitative analyses of trace levels of isomers in seawater and the results were found to be satisfactory, with no need for further clean-up procedures. 

The method was used for routine monitoring of dinitrotoluene concentrations in seawater from Dokai Bay, Japan. Both 2,6- and 2,4-dinitrotoluene were detected. Concentrations of 2,4-dinitrotoluene in surface water samples were higher than those in bottom water samples in 8 out of 10 samples. 

The nitration of dinitrotoluene to TNT requires the use of mixed acid fortified with oleum, and the use of elevated temperature, which produces its own pollutants and impurities, including tetranitromethane and nitrogen oxides. An excellent discussion of industrial TNT production has been given by Urbahski. ... 

Korolev AA, Voitesekhovskya MV, Bogdanov MV, et al. 1977. [Experimental data for hygienic standardization of dinitrotoluene and trinitrobenzene in surface waters.] Gig Sanit 10 17 (Russian)... 

Spanggord RJ, Myer CJ, LeValley SE, et al. 1990. Structure-activity relationship for the intrinsic hepatotoxicity of dinitrotoluenes. Chem Res Toxicol 3 551-558. 

Two other derivatives of toluene are the important explosive trinitrotoluene (TNT) and the polyurethane monomer toluene diisocyanate (TDI). TNT requires complete nitration of toluene. TDI is derived from a mixture of dinitrotoluenes (usually 80% o,p and 20% o,o) by reduction to the diamine and reaction with phosgene to the diisocyanate. TDI is made into flexible foam polyurethanes for cushioning in furniture (35%), transportation (25%), carpet underlay (20%), and bedding (10%). A small amount is used in polyurethane coatings, rigid foams, and elastomers. 

Toluene diisocyanate (TDI) is made from the reaction of 2,4-toluenediamine and phosgene. The diamine is made by reduction of dinitrotoluene, which in turn is manufactured by nitration of toluene. See Chapter 11, Section 7. 

We will return to these reactions later in connection with polyurethanes because one monomer in polyurethanes is toluene diisocyanate, and the first step in its synthesis is the production of dinitrotoluene. 

Another example of bubble columns is hydrogenation of olefins and other organics, such as reduction of dinitrotoluene... 

Huffington carried out his experiment with a powder containing 29% of nitroglycerine and 10% of dinitrotoluene, as mentioned before (pp. 644, 650 and 653). 

Toluene, which is more reactive than benzene, may be nitrated with a more dilute mixed acid containing about 23% of water.97,98,100 Typical isomer compositions are 57-60% ortho, 37-40% para, and 3-4% meta isomers. Although 97-98% overall yields may be achieved with less than 0.5% of dinitrotoluenes, oxidative byproducts, mainly dinitrocresols, are formed.101... 

Triplastita (Triplastite). A gelatinized mixt of Dinitrotoluene and Guncotton (Algodon pol-vora). It is less sensitive than TNT and has the advantage of a higher d when compressed. Used as a bursting charge in some ammo (Ref 9, p 31)... 

The manufacture of dinitrotoluene at the Griesheim factory (I.G. Farbenindustrie), described below, may serve as an example. 

Toluene diisocyanate is derived from a mixture of dinitrotoluenes (usually 65 to 85% o./9-dinitrotoluene and 35 to 15% o,o-dinitrotoluene) followed by reduction to the diamine and reaction with phosgene to the diisocyanate. 

Studies have indicated that repeated exposure of dinitrotoluene has resulted in testicular atrophy and disturbances in the spermatogenesis cycle in experimental mice, rats, and dogs. Female mice also revealed nonfunctioning ovaries 89,90 Conflicting reports regarding the potential reproductive toxicity of dinitrotoluene among workers demand more confirmatory data 91,92 NIOSH has classified technical dinitrotoluene as a human reproductive health hazard in industrial workplaces. Isomers of dinitrotoluene have caused complete liver cancers in animals, but technical-grade dinitrotoluene failed to induce any kind of hepatic cancer in humans.37,93... 

J.A. Popp andT.B. Leonard, The hepatocarcinogenicity of dinitrotoluenes, Chapter 4, in Toxicity of Nitroaromatic Compounds, D.E. Ricke, ed., Hemisphere, New York, pp. 53-60, 1985. 

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