Toluene nitration product

T. Krasiejko I. Missala, Analysis of Toluene Nitration Products by Gas Chromatography , ChemAnal 18 (5), 1081-83 (1973)... 

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. 

Report of the British Intelligence Objectives Subcommittee on (1) The Manufacture of Nitration Products ofBenyene, Toluene, and Chlorobenyene at Griesheim and Eeverkusen, (2) The Manufacture of Aniline andiron Oxide Pigments at Uerdigen, PB 77729 (also issued as BIOS Report No. 1144) and BIOS Trip Report No. 2526, Sept.-Oct. 1946, pp. 25-32. 

Trinitrotoluene (TNT) is made by nitration of toluene. Display electrostatic potential maps for toluene, 4-nitrotoluene (the first nitration product) and 2,4-dinitrotoluene (the second nitration product). Are the second and third nitration steps likely to be easier or more difficult than the initial nitration of toluene Explain. 

Most of the nitrated product is in the form of an emulsion and consequently is much safer to handle. The toluene that enters stage 1 leaves stage 7 as crude TNT, while the strong acid that enters stage 7 comes out as weak acid in stage 1. Man-power requirements are kept to a minimum even for 10 million pounds/year production... 

The effects of reactant feeding methods on toluene nitrations were studied by Yamasue et al (Ref 70) in a 15 liter nitrator with a 500rpm agitator. Production of pu re MNT or DNT was favored by addition of acid to the toluene or MNT, while in the production of TNT the addition of oil to acid is to be preferred, provided sufficient cooling and agitation is available. Purest TNT was produced when the MA contained free S03... 

The nitronium ion, N02 , is the active nitrating agent in nitric acid-sulfuric acid mixtures. The nitration of methylbenzene (toluene) is a typical example of a nitration that proceeds well using nitric acid in a 1 2 mixture with sulfuric acid. The nitration product is a mixture of 2-, 3-, and 4-nitromethylbenzenes ... 

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

Elton-Bott [22] and Osibanjo and Ajaya [23] determined nitrate in soil by a spectrophotometric method based on 3,4-xylenol. In one of these procedures [28], nitration of the 3,4-xylenol is carried out instantaneously at about 0 °C in 80% sulfuric acid and the nitration product is extracted into toluene, the excess of the reagent remaining in the aqueous layer. The toluene layer is then treated with sodium hydroxide solution to form a coloured product (the sodium salt of the nitrophenol in the aqueous layer), the absorbance of which is measured at 432 nm. Interferences from common anions, including chloride and nitrate, were investigated. 

The conventional nitration process,[2,5] that involves a mixture of nitric and sulfuric acids (mixed acids method) has remained unchallenged, in the commercial area, for the last 150 years owing to the very favourable economics. However, the method is notoriously unselective for nitration of substituted aromatic compounds and the disposal of waste products and spent acids is a serious environmental issue. For instance, nitration of toluene for production of mononitrotoluenes (MNTs) is conducted using a nitrating mixture usually composed of 52-56 % (w/w) H2SO4, 28-32% (w/w) HNO3 and 12-20% (w/w) H20. The reaction performed at temperatures between 25 and 40°C, yields ca. 96 % MNTs, which are composed of a mixture of ca. 60 % (w/w) o-nitrotoluene, ca. 37 % (w/w) p-nitrotoluene and... 

The order of introducing the reagents may also affect the composition of the nitration product. For example, if the toluene is added to the acid, then the first portions of toluene come into contact with a large excess of acid, and the nitration process may proceed beyond mononitration resulting in a mixture of di- and mono-nitrotoluene. If the amount of HN03 used has been calculated accurately, the last portions of toluene may be left unnitrated and the resultant product may not be uniform. If, on the contrary, the acid is added to the toluene, an excess of acid cannot occur, since each portion added reacts with the toluene very quickly. 

The latter operation (adding acid to toluene) favours the formation of tarry products (see p. 266) but at the same time the formation of higher nitrated products is avoided, as the toluene is never in contact with an excess of acid. 

How reactive are the different sites in toluene Nitration of toluene produces the three possible products in the ratios shown. What would be the ratio of products if all sites were equally reactive What is the actual relative reactivity of the three sites (You could express this as x y. 1 or as a b c where a+fo+c=l00.) Comment on the ratio you deduce. 

The synthesis of TDI begins with the nitration of toluene, using a nitric acid-sulfuric acid mixture. The nitration product typically contains at least 75 percent 2,4-dinitrotoluene with the balance mostly 2,6-dinitrotoluene, which is catalytically reduced to toluene diamine. Lastly, the diamine mixture is dissolved in chlorobenzenes and reacted with... 

E. J. Hoffman, (2) has made a study of the effects caused by the addition of the toluene to the acid, and vice versa. In his experiments with the two-stage method (nitrating first to mononitrotoluene and then to TNT), he used an acid mixture of one part nitric acid (gravity 1.42) to two parts sulphuric acid (gravity 1.84). When the toluene was added to the acids the yield was 60 per cent mononitrotoluene and 40 per cent dinitrotoluene. On the other hand, when the acids were added to the toluene very little dinitrotoluene was formed. The temperature was more easily controlled in the first procedure, in which the toluene was added to the acid. Providing the nitration product is to be further nitrated to TNT, the presence of the dinitrotoluene is not objectionable. Hoffman s yield with this method was 75 per cent of TNT with a melting-point of 78 to 80° C. 

The product which results from the application of the various processes outhned in the previous chapter is known as crude TNT. To define the word crude as applied to TNT is rather difficult, since a crude product is generally thought of as being a product that is contaminated with foreign substances. The purified product differs from the crude product in that these foreign matters are removed. As a matter of fact, crude " TNT contains no real impurities, in the true sense of the word, because the impurities have been removed in the washing of the crude product. There are, it is true, other compounds of nitric acid and toluene (the lower nitration products), in the TNT, and... 

Zeta dinitrotoluene is prepared from the nitration products of toluene. 

Processes that have been commercialized for production of cresois from toluene have been mostly an adaptation and extension of those used for manufacture of phenol, from benzene. As in the case of phenol the three most important processes for manufacture of cresois from toluene (nitrate grade) are based on... 

Nitration of toluene for production of mononitrotoluenes (MNT) is conducted either batch-wise or in continuous operation under somewhat milder conditions than those used for benzene nitration because of the activating effect of the methyl group. The nitrating acid usually has the composition 52-56% (w/w) H2SO4,... 

Tapia et al. [23] described the use of nitric acid supported on silica gel for the mono-nitration of activated aromatic compounds such as phenols and aryl methyl ethers. Riego et al. [24] used sulfuric acid supported on silica gel for the mononitration of a variety of aromatic compounds. The reaction was performed at ambient temperature with 70 % nitric acid or isopropyl nitrate as reagents and yielded mono-nitrated products within short reaction periods. Toluene was quantitatively converted to NT in 0.1 h, without a solvent, by use of a catalyst containing 10 mmol g as supported 70% H2SO4. A comparative study of the reaction kinetics of the nitration using supported and unsupported liquid acids revealed that the performance of supported sulfuric acid is comparable with that of 90 % sulfuric acid in the classical liquid phase reaction where complete protonation of nitric acid occurs [25]. 

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