Picric acid is a complex chemical substance that is a nitro derivative of phenol. By the way, this compound in science is known as trinitrophenol. The substance itself, as well as its salts, are used as explosives.
Picric acid: formula and physical properties
The formula of trinitrophenol is as follows:
C6H2 (NO2) 3OH
In its pure form, picric acid is a solid that consists of plate crystals. Such crystals can either be colorless or have a faint yellowish tint. The melting point of this substance is + 122.5 degrees Celsius.
The taste of trinitrophenol is very bitter, and its dust strongly irritates the nasal passages. Prolonged inhalation of the substance is dangerous for the human body, as it leads to poisoning, kidney damage and the appearance of skin diseases. Undesirable contact of the substance with the mucous membranes. For example, the conjunctiva of the eyes after getting dust of picric acid gains a yellowish tint.
Picric acid: chemical properties and basic characteristics
Trinitrophenol is poorly soluble in water, although its solubility increases with increasing temperature. However, benzene is also an ideal solvent for this substance, as well as methanol, chloroform and acetone.
Picric acid is also capable of forming so-called eutectic mixtures. The fact is that a high melting point creates some technological difficulties when loading ammunition. And when creating a mixture with nitronaphthalene or trinitrocresol, this figure can be partially reduced.
It is also worth noting that trinitrophenol is a fairly strong acid, which quickly and actively enters into metabolic reactions. As a result of interaction with metals, salts are formed - the so-called picrates. The most commonly used salts are lead, sodium, iron and calcium. Interestingly, picric acid salts are more sensitive, which requires extra caution in the manufacture of ammunition.
Picric acid and explosive devices
In history, it was trinitrophenol that became the first effective explosive. The explosive properties of acid and its salts were discovered around the end of the eighteenth century, but it began to be actively used during military operations only in the 30s of the 19th century.
The use of trinitrophenol gave a new impetus to the development of military equipment. The fact is that picrates and picric acid itself had significantly greater impact and destructive properties than gunpowder, which was used in those days.
Such explosives reached a peak in popularity during the Second World War. Today, this technology is practically not used.
How to get trinitrophenol?
Picric acid can be obtained during the direct phenol nitration reaction using high concentration nitrate acid. But before thinking about where to buy nitric acid, it is worth noting that the process of producing picrin or picrates is very dangerous. History knows many tragic cases connected with it.
Use of picric acid
In fact, trinitrophenol is used not only to create explosives. This compound is widespread in other areas of industry. For example, picrin is an intermediate in the manufacture of certain dyes.
The substance has also been recognized in the medical field, where it is sometimes used as an antiseptic.
In the production of metals, picric acid is used as an etchant. And in the chemical industry it is used as a catalyst during polymerization reactions. Pigments are also prepared from it for staining samples in histology or for labeling laboratory animals.