Picric acid

The picric acid or acid carbo-nitric (or mélinite) is the general term for the chemical Composé 2,4,6-trinitrophenol , (NO₂) ₃C₆H₂-OH

It is a solid Cristal yellow, toxic flax and very reagent, manufactured starting from the Chlorobenzène.
Comme all the highly nitrogenized compounds (for example the Trinitrotoluene or the Nitroglycerin), it is a Explosif, with a power slightly higher than that of the TNT.

Explosiveness

The rate detonation of the picric acid is of 7650 meters/dry to its maximum density obtained by compression. Dryness, it is more sensitive to the Choc S and the Frottement S that added with water (one says that water the " flegmatise"), but a little less than the TNT and much less than the Hexogen or the Penthrite. It is one of the secondary explosives most stable. It is even more stable if it is recristallized after fusion. But, for safety reasons, its transport is carried out in wet form (30% or more H₂O), and the laboratories which use it preserve it also thus, always in containers out of glass (not in Cristal, which contains lead, nor out of plastic, because this acid can form with certain metals, in particular copper, of unstable salts (Picrate S), explosives and, particularly dangerous).

Characteristic

Not very water soluble, ether, alcohol; soluble in the Benzene and acetone (propanone)
Explodes with the top of 300 °C.
Uses: explosives, dye, therapeutic
Main risk: explosion by shock, friction, fire

to see the article of the wikilivre of tribology.

It produces salts (metal compounds) explosive very sensitive, of picrates…
Couleur: yellowish

Classification of safety

R2 Risque explosion by the shock, the friction, the fire or other sources of ignition.
R4 Forme very sensitive metal compounds.
Toxic R23 by inhalation.
Toxic R24 by contact with the skin.
Toxic R25 in the event of ingestion.
R36 Irritating for the eyes.
R37 Irritating for the respiratory tracts.
R38 Irritating for the skin.

In Canada, it is classified like " dangerously réactif'" under classification SIMDUT (Information system on the dangerous matters used with work).

Use

Like explosive (under the name of Mélinite): Whereas the coal from which one extracts his basic principle (the phenol) was abundant, the picric acid was very much used during the First World War, especially in the Obus whose filling was facilitated by a relatively low melting point (122,5°C) compared to its temperature of decomposition (300°C), ensuring the operators a good safety margin.
cutaneous Tests (formerly).
Dye (dyeing of wool). (formerly).
Tanning of the bearings of the legs of rabbits to make them more resistant to nettings of rabbit burrow (formerly).
sharp yellow Dye for the Plating of wood, used diluted (proportion from 1,5 to 3 per 1000) in the form of bath, often in combination with the iron sulfate (this one is used as hooker and gives a color gray-blue) to obtain a sharp green in particular used for the points of Trictrac (equivalent of the jacquet or Backgammon with the 18°siècle).

Nowadays, the picric acid is one of the ingredients of the liquid of Bouin, a medium of conservation used for the taking away in Anatomo-pathology.

It is component reagent proportioning the Créatinine in blood by the method of Jaffé.
It is an effective remedy for the Brûlure S (but little used because of its explosiveness).

Ecotoxicology

Total impacts of the picric acid on the Environment (mushrooms, flora, fauna, bacteria.) do not seem to be very studied. This acid is the principal explosive (mélinite) million not exploded shells of the First World War, to some extent recovered after war, but often immersed at sea. It is likely to contaminate surround it, with the 21e century when these shells are suffisemment corroded. In addition to the Toxic risk and ecotoxic, exists a risk of explosion following the formation of Picrate S. Or of the picric acid can be present in not exploded chemical weapons or in ammunition stored near these last.

See too

Internal bonds

Ammunition, immersed Ammunition, not-exploded Ammunition
Picrate

External bond

Card of safety of the Picric acid

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