Trinitrotoluene (TNT) structure, properties, uses, risks, explosion

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David Holt

The trinitrotoluene is an organic compound made up of carbon, oxygen, hydrogen and nitrogen with three nitro -NO groupstwo. Its chemical formula is C6Htwo(CH3)(NOTtwo)3 or also the condensed formula C7H5N3OR6.

Its full name is 2,4,6-trinitrotoluene, but it is commonly known as TNT. It is a white crystalline solid that can explode when heated above a certain temperature.

2,4,6-trinitrotoluene crystals, TNT. Wremmerswaal [CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)]. Source: Wikimedia Commons.

The presence in trinitrotoluene of the three nitro -NO groupstwo favors the fact that it explodes with some ease. For this reason, it has been widely used in explosive devices, projectiles, bombs and grenades..

It has also been used for blasting underwater, in deep wells and for industrial or non-war explosions..

TNT is a delicate product that can also explode from very strong blows. It is also toxic to humans, animals and plants. The places where their explosions have occurred have been contaminated and investigations are being carried out to eliminate the remains of this compound.

One way that can be effective and inexpensive to reduce the concentration in the contaminated environment of TNT is through the use of some types of bacteria and fungi..

Article index

  • 1 Chemical structure
  • 2 Nomenclature
  • 3 Properties
    • 3.1 Physical state
    • 3.2 Molecular weight
    • 3.3 Melting point
    • 3.4 Boiling point
    • 3.5 Flash point
    • 3.6 Density
    • 3.7 Solubility
    • 3.8 Chemical properties
  • 4 TNT explosion process
    • 4.1 Oxidation reaction of TNT
  • 5 Obtaining the TNT
  • 6 Uses of TNT
    • 6.1 In military activities
    • 6.2 In industrial applications
  • 7 Risks of TNT
  • 8 Pollution of the environment with TNT
    • 8.1 Solution to TNT contamination
    • 8.2 Remediation with bacteria and fungi
    • 8.3 Remediation with algae
  • 9 References

Chemical structure

2,4,6-Trinitrotoluene is made up of one molecule of toluene C6H5-CH3, to which three nitro -NO groups have been addedtwo.

The three nitro -NO groupstwo they are symmetrically located on the benzene ring of toluene. They are found in positions 2, 4 and 6, where position 1 corresponds to methyl -CH3.

Chemical structure of 2,4,6-trinitrotoluene. Edgar181 [Public domain]. Source: Wikimedia Commons.

Nomenclature

- Trinitrotoluene

- 2,4,6-Trinitrotoluene

- TNT

- Trilite

- 2-Methyl-1,3,5-trinitrobenzene

Properties

Physical state

Colorless to pale yellow crystalline solid. Needle-shaped crystals.

Molecular weight

227.13 g / mol.

Melting point

80.5 ºC.

Boiling point

It does not boil. Decomposes with an explosion at 240 ° C.

Flashpoint

It is not possible to measure it because it explodes.

Density

1.65 g / cm3

Solubility

Almost insoluble in water: 115 mg / L at 23 ° C. Very slightly soluble in ethanol. Very soluble in acetone, pyridine, benzene and toluene.

Chemical properties

May decompose explosively when heated. Upon reaching 240 ° C it explodes. It can also explode when suffering very strong blows.

When heated to decomposition it produces toxic gases of nitrogen oxides NOx.

TNT explosion process

The explosion of TNT leads to a chemical reaction. Basically it is a combustion process in which energy is released very quickly. In addition, gases are emitted which are agents to transfer energy.

TNT easily explodes when heated above 240 ° C. Author: OpenClipart-Vectors. Source: Pixabay.

For a combustion reaction (oxidation) to occur, fuel and oxidant must be present.

In the case of TNT, both are in the same molecule, since the carbon (C) and hydrogen (H) atoms are the fuels and the oxidant is the oxygen (O) of the nitro -NO groups.two. This allows the reaction to be faster.

TNT oxidation reaction

During the combustion reaction of TNT, the atoms rearrange themselves and oxygen (O) remains closer to carbon (C). In addition, the nitrogen of -NOtwo is reduced to form nitrogen gas Ntwo which is a much more stable compound.

The explosion chemical reaction of TNT can be summarized as follows:

2 C7H5N3OR6 → 7 CO ↑ + 7 C + 5 HtwoO ↑ + 3 Ntwo

Carbon (C) is produced during the explosion, in the form of a black cloud, and carbon monoxide (CO) is also formed, which is because there is not enough oxygen in the molecule to completely oxidize all the carbon atoms ( C) and hydrogen (H) present.

Obtaining TNT

TNT is a compound made only artificially by man.

It is not found naturally in the environment. Occurs only at some military installations.

It is prepared by nitration of toluene (C6H5-CH3) with a mixture of nitric acid HNO3 and sulfuric acid HtwoSW4. First you get a mixture of ortho- Y in order to-nitrotoluenes which by subsequent energetic nitration form the symmetric trinitrotoluene.

Uses of TNT

In military activities

TNT is an explosive that has been used in warlike devices and military explosions.

Hand grenades can contain TNT. Authors: Materialscientist, Nemo5576, and Tronno. Source: Wikimedia Commons.

It is used to fill projectiles, grenades and airborne bombs, since it is insensitive enough to the impact received to leave the barrel of a weapon, but can explode when hit by a detonator mechanism.

Aerial bombs can contain TNT. Author: Christian Wittmann. Source: Pixabay.

Not designed to produce significant fragmentation or launch projectiles.

In industrial applications

It has been used for explosions of industrial interest, in underwater blasting (due to its insolubility in water) and deep well explosions. In the past it was most often used for demolitions. It is currently used together with other compounds.

Photo of the result of an explosion to demolish rocks in 1912. At that time TNT was used in blasting required for example to open roads for railways. Internet Archive Book Images [No restrictions]. Source: Wikimedia Commons.

It has also been an intermediary for colorants and photographic chemicals.

Risks of TNT

May explode if exposed to intense heat, fire, or very strong shocks.

It is irritating to the eyes, skin and respiratory tract. It is a very toxic compound both for humans and for animals, plants and many microorganisms..

Symptoms of TNT exposure include headache, weakness, anemia, toxic hepatitis, cyanosis, dermatitis, liver damage, conjunctivitis, poor appetite, nausea, vomiting, diarrhea, among others..

It is a mutagen, that is, it can change the genetic information (DNA) of an organism causing changes that can be related to the appearance of hereditary diseases.

It has also been classified as a carcinogen or cancer generator.

Pollution of the environment with TNT

TNT has been detected in soils and waters in areas of military warfare operations, in ammunition manufacturing sites and where military training operations are carried out..

The soils and waters of war zones or military operations have been contaminated with TNT. Author: Michael Gaida. Source: Pixabay.

Contamination with TNT is dangerous to the life of animals, humans and plants. Although TNT is currently used in smaller quantities, it is one of the nitroaromatic compounds that have been used the most in the explosives industry..

For this reason, it is one of those that contributes the most to environmental pollution..

Solution to contamination with TNT

The need to "clean" regions contaminated with TNT has motivated the development of several remediation processes. Remediation is the removal of pollutants from the environment.

Remediation with bacteria and fungi

Many microorganisms are capable of bioremedying TNT, such as bacteria of the genus Pseudomonas, Enterobacter, Mycobacterium Y Clostridium.

It has also been found that there are certain bacteria that have evolved in places contaminated with TNT and that can survive and also degrade or metabolize it as a nutrient source.

The Escherichia coli For example, it has shown an outstanding capacity for biotransformation of TNT, since it has multiple enzymes to attack it, demonstrating at the same time a high tolerance towards its toxicity.

In addition, some species of fungi can biotransform TNT, turning it into non-harmful minerals..

Algae remediation

On the other hand, some researchers have found that the alga Spirulina platensis has the ability to adsorb on the surface of your cells and assimilate up to 87% of the TNT present in water contaminated with this compound.

The tolerance of this algae towards TNT and its ability to clean water contaminated with it indicate the high potential of this algae as a phytoremediator..

References

  1. U.S. National Library of Medicine. (2019). 2,4,6-Trinitrotoluene. Recovered from pubchem.ncbi.nlm.nih.gov.
  2. Murray, S.G. (2000). Explosives. Mechanism of Explosion. In Encyclopedia of Forensic Sciences 2000, Pages 758-764. Recovered from sciencedirect.com.
  3. Adamia, G. et al. (2018). About possibility of alga Spirulina application for phytoremediation of water polluted with 2,4,6-trinitrotoluene. Annals of Agrarian Science 16 (2018) 348-351. Recovered from reader.elsevier.com.
  4. Serrano-González, M.Y. et al. (2018). Biotransformation and degradation of 2,4,6-trinitrotoluene by microbial metabolism and their interaction. Defense Technology 14 (2018) 151-164. Recovered from pdf.sciencedirectassets.com.
  5. Iman, M. et al. (2017). Systems Biology Approach to Bioremediation of Nitroaromatics: Constraint-Based Analysis of 2,4,6-Trinitrotoluene Biotransformation by Escherichia coli. Molecules 2017, 22, 1242. Recovered from mdpi.com.
  6. Windholz, M. et al. (editors) (1983). The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. Tenth Edition. Merck & CO., Inc.
  7. Morrison, R.T. and Boyd, R.N. (2002). Organic Chemistry. 6th Edition. Prentice-Hall.

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