A picrate is a

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...

containing the anion (O₂N)₃C₆H₂O⁻ or an

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

derivative of the picrate anion. These salts are often produced by reactions of

picric acid Picric acid is an organic compound with the formula (O2N)3C6H2OH. Its IUPAC name is 2,4,6-trinitrophenol (TNP). The name "picric" comes from el, πικρός (''pikros''), meaning "bitter", due to its bitter taste. It is one of the most acidic ...

(2,4,6-trinitrophenol). The picrate ion is intensely yellow, although many of its salts are brown or orange-red.

Explosives

Many picrates are

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...

s, for example

ammonium picrate Dunnite, also known as Explosive D or systematically as ammonium picrate, is an explosive developed in 1906 by US Army Major Beverly W. Dunn, who later served as the chief inspector of the Bureau of Transportation Explosives. Ammonium picrate is ...

(known as

Dunnite Dunnite, also known as Explosive D or systematically as ammonium picrate, is an explosive developed in 1906 by US Army Major Beverly W. Dunn, who later served as the chief inspector of the Bureau of Transportation Explosives. Ammonium picrate is ...

). Some are used as primary explosives, namely

lead picrate Lead picrate is an organic picrate salt. It is a sensitive and highly explosive compound that is typically found as a hydrate. Dry lead picrate is incredibly dangerous and cannot be handled without explosive decomposition occurring. History ...

potassium picrate {{chembox , Verifiedfields = changed , Watchedfields = changed , verifiedrevid = 428744204 , ImageFile =Potassium picrate.svg , ImageSize = , PIN = Potassium 2,4,6-trinitrophenoxide , OtherNames = Potassium 2,4,6-trinitrophenolate; Picric aci ...

which find their use as primers for cartridge

ammunition Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weap ...

. Picrates of some metals tend to be significantly more sensitive to impact, friction and shock than picric acid itself. As a result, storage of picric acid (or mixtures containing it) in metal containers is strongly discouraged due to the high risk of accidental explosion.

Other uses

Ferrous picrate is used in some applications as a diesel

fuel additive Petrol additives increase petrol's octane rating or act as corrosion inhibitors or lubricants, thus allowing the use of higher compression ratios for greater efficiency and power. Types of additives include metal deactivators, corrosion inhib ...

to achieve better mileage. Sodium picrate is used as an etchant in

metallography Metallography is the study of the physical structure and components of metals, by using microscopy. Ceramic and polymeric materials may also be prepared using metallographic techniques, hence the terms ceramography, plastography and, collectiv ...

to differ preeutectoid ferrite in hypoeutectoid steel from preeutectoid

cementite Cementite (or iron carbide) is a compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula Fe3C. By weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure. It is a hard, brit ...

in hypereutectoid steel by

etching Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other types ...

cementite to a dark colour, whereas not attacking ferrite and thus it remains reflective.

Ethers and esters

Ethers and esters of picric acid are also called picrates. The ether methyl picrate (CAS# 606-35-9) has the formula (O₂N)₃C₆H₂OCH₃.

References

{{Reflist