Trinitrotoluene
| of these articles is occupied with the explosive TNT. For further meanings see TNT (term clarifying). |
| Structural formula | |||||||
|---|---|---|---|---|---|---|---|
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| general | |||||||
| name | trinitrotoluene | ||||||
| other names | 2,4,6-Trinitromethylbenzen, TNT, Trotyl, ON, FP-02, Tol, Tolite, Tritol, Trisol, Tutol | ||||||
| sum formula | C 7 H 5 N 3 O6 | ||||||
| CAS number | 118-96-7 | ||||||
| short description | lightyellow, needle-shaped crystals | ||||||
| characteristics | |||||||
| mol mass | 227.13 g mol | ||||||
| state of aggregation | firmly | ||||||
| density | 1.65 g/cm ³ | ||||||
| melting point | 80.35 °C | ||||||
| boiling point | 300 °C (decomposition) | ||||||
| steam pressure | 0,057 hPa (81 °C) | ||||||
| solubility | well in Ether, acetone, Benzen, badly in water | ||||||
| of safety references | |||||||
| of Gefahrensymbole | |||||||
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| R and S-sentences |
of R: 2-23/24/25-33-51/53 | ||||||
| MAK | 0.1 mg/m ³ | ||||||
| as far as possible and common, are used SI-UNITs. If not differently notes, the indicated data apply with standard conditions. | |||||||
Trinitrotoluene (TNT) is an explosive. The sum formula reads C 7 H 5 N 3 O 6.
The correct name for TNT is in accordance with the nomenclature of the IUPAC 2,4,6-Trinitromethylbenzen. In this article become the more common designations trinitrotoluene and toluol (instead of Toluenand/or. Methylbenzen) uses.
TNT was manufactured by Joseph Wilbrand in the year 1863, the large-scale production to Germany 1891 was for the first time taken up.
The explosive yield from TNT became the yardstick the strength from bombs and other explosives (see TNT equivalent).
Table of contents |
Characteristics
trinitrotoluene forms lightyellow, needle-shaped crystals and can in the vacuum be distilled. In water it is very with difficulty solubly, well solubly however in Ether, acetone, Benzen and Pyridin. With his low melting point of 80,8 °C leavesTNT in water vapour melt themselves and can in forms be poured. TNT is poisonous and can cause allergische reactions with skin contact. It colors the skin bright for yellow-orange.
- Water solubility: 130 mg/L with 20°C
- steam pressure with 20°C: 1,5 -6 mbar
- of Detonationsgeschw.: 6700-7000m/s 6900 m/s (density: 1,6 g/cm ³)
- remaining LOCK bulge: 300 ml/10 g
- sensitivity to impact: 15 Nm (1.5 kpm)
- friction sensitivity: to 353 N (36 kp) no reaction
production
past
TNT became for the first time 1863 of Joseph Wilbrand in impure form synthesizes. With the development of the pure synthesis 1880 by P. Hepp and the discovery explosive by Häussermann, suitable of TNT as , 1889 came it into Germany since 1891 to industrial production. Particularly by the needthe military at TNT as filling of shells rapidly numerous factories developed. The basic material for the production of trinitrotoluene, Toluen (toluol), could be manufactured at that time however only in limited quantity, since one was dependent on the production from coal tar, oneMixture from thousands of single substances, which results during the coke production. From today's viewpoint this method is however no longer economical, since the portion of toluol is relatively small in the coal tar.
In the Second World War TNT was again strengthened produced. So-called “sleep factories”before war beginning were already established, mostly with double execution of the plants, so that when destruction and damages far explosive could be manufactured. The produced quantities had drastically increased. Thus amounted the quantity in the German Reich produced TNT to 18.000Tons per month, during the war became altogether approx. 0,8 million tons manufactured. This increase was possible, because the necessary Edukt could be won now also from oil. During a two-stage process, „the German procedure “, toluol became first simplenitrated. The developed Mononitrotoluol (MNT) one cleaned of unwanted by-products and nitrated again, whereby over Dinitrotoluol (DNT) desired raw TNT was produced. After repeated washing and drying it could be granulated and processed then. Safety precautions thereby neglected over forTo ensure supply at the front. Since TNT long time was considered innocuous, one neutralized only the wastes and let her into nature waters flow, where they partly settled in the form of mud and damage than arms refuse dumps the environment.Regarding the unknown toxicity it is well-known that between 1911 and 1915 279 ammunition workers died, because they had taken small quantities over skin and respiratory system to itself.
present
nowadays takes place the technical production via the thermal Cracken of oil and the platinum Reforming with following Dehydrocyclisierung, briefly Platforming, with which from alkanes and cycloalkanes aromatics are won. While hydrogen by catalysts from platinum or alumina abgespalten will (dehydrogenation), changes the alkanes their structure to rings (Cyclisierung) and to formthen the delokalisierte electron system out. So heptane can be converted to toluol.
Also the possibility exists to insert into aromatics already existing an alkyl group. 1877 developed Friedel Craft this procedure, which was designated therefore after this. With aluminum halides as catalystreacts Benzen with alkyl halides.
In the technical conversion it is aluminum chloride, which activates the alkyl halide. This is able to polarize the latter ever further, as long as to the alkyl group by the halogen one splits and an electron deficiency exhibits, so that it to the elektrophilenAlkyl residue becomes.
This stands thereby ever more in reciprocal effect with the π-electron cloud of the Benzen - molecule. The elektrophile attack takes place. A Carbeniumion develops consisting of the Benzen and the alkyl residue, which are connected by a σ-connection. Now must onlystill the proton (hydrogen) it abgespalten becomes with which this kind of the raw material extraction was already based on a elektrophilen substitution reaction at aromatics SE (acre). The more exact argument with this reaction takes place however at another point.
Friedel strength alkylation has limiting factors, those thoseYield and thus generally economic meaning substantially lower. Alkyl benzenes are in the elektrophilen substitution at aromatics more reactively than Benzen themselves; therefore the straight only developed alkyl benzene tends to react to two and several times alkylated products. The production of toluolfor TNT becomes smaller:
One actually uses immense quantities, there the raw materials economically is isolated continuous and developed toluol. Because the chemical procedures run all in the form of Gleichgewichtsreaktionen and thereby on pages Monomethylbenzen are shifted.
Inductive and mesomerer effect
the reaction rate of the elektrophilen substitution at aromatics crucially by the activation energy and two effects, which determines inductive ones and the Mesomeren, which both effect on the electron density in aromatics will have.
The inductive effect is a polarization effecton „the key atom “over single bonds under the Elektronegativität of the atoms in the molecule. [[+I-effect]] e, as they arise at groups of methyls, increase the electron density to aromatics, - I-effects, with carboxyl and hydroxyl groups, reduce them. For the SE (acre) is important: The more highly thoseElectron density, the more reactively is that aromatic.
More strongly than the inductive effect is mostly however the Mesomere. It comes off, as free pairs of electrons or π-electrons of double bonds of a substituent stand in reciprocal effect with the electron system of the carbon ring and likewise thoseElectron density either increase or lower. With the positive mesomeren effect a free pair of electrons can slide itself into the core, whereby reactivity increases clearly. Examples of this is the effect of the substituents: Hydroxylatgruppe, amino group and halogen. - M-effect extracts from the coreElectrons. Among this substituents also the Nitrogruppe ranks.
secondary substitution: Nitrating the Toluen
for the production of TNT must be only nitrated toluol with Nitriersäure. Nitriersäure is consisting a special acid of 1/3 sulfuric acid and 2/3Nitric acid. First is able to polarize the nitric acid due to its strength ever further and finally protonieren. With the remaining NO2+-Ion, the Nitryl cation or Nitroniumion, an electron deficiency is present and is extreme therefore elektrophil whereby the Nitriersäure is stronger than normalNitric acid.
Differently than with the formation toluol changes the appearance of the molecule thereby at which carbon it is attacked. Because altogether eight different trinitrotoluenes are conceivablly, only the symmetrical of those, the 2,4,6-Trinitrotoluol, which is wishing. The explanationis in the stability of the Interdukte to developing trinitrotoluenes. The more mesomeriestabilisierter a product is, is the more probably its education. We can examine this, by seizing and comparing the border formulas for possible structures.
Five different points of attack are conceivable, howtwice two due to the symmetry of the molecule are identical. One designates these points, where the Elektrophil attacks, after the carbon atoms were DEK-lined on the basis the functional group, as ortho (2.tes C-atom), meta (3.tes C-atom), and para position (4.tes C-atom).
By that inductive effect of group of methyls in toluol become with 96%-iger probability 2. -, 4. - and 6. - Mononitrotoluol in an educated manner, which can be used all for 2,4,6-Trinitrotoluol. Groups of methyls therefore cause a elektrophilen attack to ortho and para position. It is directed there „“, becausethese two positions in each case a border formula of the Carbeniumions compared with the others an energetically particularly favorable structure exhibits and thus is generally more mesomer more stable.
third and fourth substitution
the formed Mononitrotoluol possess now a further functional group,those the further reaction behavior contributes. The Nitrogruppe lowers the electron density in the core, since the nitrogen atom receives a positive Teilladung by the strongly electronegative sour materials and so that also to the increase of the electron density to the order cannot place electrons. NO2+ causes thusa negative inductive and mesomeren effect. Now if a further Nitroniumion attacks our MNT elektrophil, then now methyl and Nitrogruppe determine together the point of attack. Again the view of the possible border formulas is important, in order to understand the procedures. First we pursuethe further reaction behavior of the earliest formed product, 2. - and/or. 6. - Mononitrotoluol.
Interestingly enough again two Carbeniumionen favoured by group of methyls are conceivable with attack in ortho and para position (B+D). But also the Nitrogruppe promotes these possibilities at the same time, by her, are there the meta positions (A+C) avoid the other two positions for the Nitroniumion from smaller stability. Reason for it is the proximity of the two positive Teilladungen over the carbon ring and nitrogen atom, which repel themselves both. Literature data mean that with thatelektrophilen themselves secondary substitution aromatics with the Erstsubstituenten of a NO2 to 93% product in meta, to 6% in ortho and 1% in para position devoted. In the case of our Carbeniumion a meta position actually results, if the Nitrogruppe as functional group decisive forthe carbon numbering is. Thus further statements about the yield can be met. Data for the secondary substitution are:
The grey angefärbten fields indicate the same position in this case. The meta position for the Nitrogruppe can thus either together withfavouring arise to the ortho position or with the para position for group of methyls. It is to be accepted thus justified that the yields of the DNT are almost identical to those of the MNT.
The further reaction 4. - One can reconstruct Mononitrotoluol now simply. Due toSymmetry are relevant only two Carbeniumionen, with whose Mesomerie again an already well-known stable and a new less favorable arise. The Nitrogruppen reduces occupation ortho and para positions. Also the final way from the DNT to the TNT is nowevidently. Because with highest probability now fifth carbon will be attacked and we receives a symmetrical structure.
If one possesses the cheap and raw materials which can be acquired simply, then the reaction of these runs independently to our explosive. But itself none should More inexperienced without more appropriately technical equipment to this production dare. Even the products already developed can bring the energy set free with the formation of the Nitroniumionen in the Nitriersäure to the explosion. A sufficient cooling is from greatest importance. The production of TNTis not recommended for laymen. Toluen is injurious to health and the work causes a Luftabzug, the Nitriersäure is dangerous because of possible heavy Verätzungen, in addition rivet rose gases release when its production. The moreover one the final product TNT is very poisonous andits large explosive yield can be easily underestimated by laymen!
laboratory yardstick
in principle is dripped toluol into a container with the Nitriersäure; the container with the Nitriersäure must be always cooled. In a first step the Toluen becomesMono, in second to the and finally to the trinitrotoluene nitrates; so that if possible entire toluol is converted to the TNT, the Nitriersäure must be sufficiently strong. TNT crystallizes to a solid and can by means of a filter of the Nitriersäureare taken.
In practice harsche conditions must prevail, so that the transformation of the Nitrotoluols succeeds to the TNT. The secondary substitution happens about only at temperatures around 100° C; TNT production causes by it pressure and heat-firm of reaction containers.
use
TNT is one of the most important military explosives and has a detonation speed of 6900 m/s. Use he finds both in the military and in the commercial range and safety explosive, which can be brought only by Initialzündung ( for example by means of blasting cap) to detonating. PouredTNT even needs an amplifier charge, a so-called for the safe ignition. Booster. TNT alone cannot be brought by fires or heat to the explosion; it burns down simply. Due to the high manufacturing costs (about the twentyfold of commercial explosives) is its main operational area howeverprimarily the military range, in which it comes as engagements charge from for example shells , bombs and mines to the employment.
The energy content amounts to in SI - units:
- 1 megaton TNT = 4.6 Petajoule (4,6 · 10 15 joules)
- of 1 kt TNT =4.6 Terajoule (4,6 · 10 12 joules)
- of 1 t TNT = 4.6 Gigajoule (4,6 · 10 9 joules)
- of 1 kg TNT = 4.6 megajoules (4,6 · 10 6 joules)
frequently in connection with atomic explosions used unit TNT equivalent is basedhowever on the calorie and is defined by
- 1 KT (kiloton TNT) = 10 12 cal = 4.184 · 10 12 J.
The units megaton and Gigatonne are similarly defined. By capitalization is the mistake with the Masseneinheit kiloton are prevented.
why does TNT explode?
TNT is reliably the most well-known chemically homogeneous explosive. It owes its Explosivität, like all homogeneous explosives, to its chemical instability. Chemically homogeneous explosives do not consist of a mixture of fuel and oxidizer (howe.g.Black powder), but from only one substance. The fuel (carbon), necessary for the explosion, and the oxygen are bound thereby in the molecule of the substance, but by a small active element from each other separated (usually nitrogen). Throughthe proximity of burning and oxygen on molecular level and by the fine dispersion in the smallest possible (atomic) yardstick can be achieved an optimal conversion of the reaction partners.
By a suitable procedure (heating, impact or both) if energy is supplied to the substance, that becomeslimited stably stored nitrogen atom between carbon and oxygen far away and the elements are connected. If a sufficient quantity of the substance was ignited, the delivered energy keeps this reaction upright and the entire amount of material is converted. This conversion takes place in one muchfast, narrow reaction zone, which goes through similarly a wave the substance. The speed of this reaction zone reached with efficient explosives several thousand meters per second, exceeds thus the internal-material speed of sound. Connected with it it comes to an extremely steep pressure and temperature rise, whichthe efficiency of explosive explosives justifies.
The picture shows only the basic principle. In reality still further reaction products develop with the detonation of TNT. Because of the too small oxygen portion in the molecule among other things poisonous materials develop such as Carbon monoxide and Zyanwasserstoff (prussic acid).
Practically all military explosives are based on homogeneous explosives, which will nearly always provide however for the increased safety, for the increase of the achievement or for the extension of the spectrum of use with different aggregates.
chemical used explosives
literature
- smelling pool of broadcasting corporations Escales: Nitrosprengstoffe. Survival press, 1915 Reprint 2003, ISBN 383301143
- W. Woodlouse fount, M. Jäckel, Dr. K. T. Risch: Secondary range II chemistry today: Hanover 1998: Schroedel publishing house
- H. J. Quadbeck - Seeger, R. Fist, G. Knaus,And. Siemling: Chemistry record humans, markets; Molecules: Weinheim; New York; Chichester; Brisbane, Singapore; Toronto 1997: Wiley - Vch
- Dr. H. - D. Barke, K. Extension ore, M. Jäckel, Dr. J. Jaenicke, G. Jug, H. Eye, E. Petrak, W. Roughly, And. Deer leg, Dr. K.Risch: Secondary range I chemistry today: Hanover 1988: Schroedel publishing house
- M.E.Walsh, T.F.Jenkins, P.S.Schnitker, J.W.Elwell, M.H.Stutz: “Evaluation OF SW846 Method of 8330 for charactzerization OF of sites contaminated with residues OF high explosive”, CRREL report 93-5, U.S.Army Cold region Research and engineering Laboratory, Hanover,NH
