Picric acid is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

with the formula (O₂N)₃C₆H₂OH. Its

IUPAC name In chemical nomenclature, a preferred IUPAC name (PIN) is a unique name, assigned to a chemical substance and preferred among the possible names generated by IUPAC nomenclature. The "preferred IUPAC nomenclature" provides a set of rules for cho ...

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

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

phenols In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of one or more hydroxyl groups (— O H) bonded directly to an aromatic hydrocarbon group. The simplest is phenol, . Phenolic compounds are c ...

. Like other strongly

nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...

d organic compounds, picric acid is an

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 ...

, which is its primary use. It has also been used as medicine (antiseptic, burn treatments) and as a dye.

History

Picric acid was probably first mentioned in the

alchemical Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in China, India, the Muslim world, ...

writings of

Johann Rudolf Glauber Johann Rudolf Glauber (10 March 1604 – 16 March 1670) was a German-Dutch alchemy, alchemist and chemist. Some historians of science have described him as one of the first chemical engineers. His discovery of sodium sulfate in 1625 led to t ...

. Initially, it was made by

nitrating In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group into an organic compound. The term also is applied incorrectly to the different process of forming nitrate esters between alcohols and ...

substances such as animal horn,

silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the coc ...

indigo Indigo is a deep color close to the color wheel blue (a primary color in the RGB color space), as well as to some variants of ultramarine, based on the ancient dye of the same name. The word "indigo" comes from the Latin word ''indicum'', m ...

, and natural

resin In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on natu ...

, the synthesis from indigo first being performed by

Peter Woulfe Peter Woulfe (1727–1803) was an Anglo-Irish chemist and mineralogist. He first had the idea that wolframite might contain a previously undiscovered element (tungsten). In 1771, Woulfe reported the formation of a yellow dye when Indigo dye, ind ...

during 1771. The German chemist

Justus von Liebig Justus Freiherr von Liebig (12 May 1803 – 20 April 1873) was a German scientist who made major contributions to agricultural and biological chemistry, and is considered one of the principal founders of organic chemistry. As a professor at t ...

had named picric acid (rendered in French as ). Picric acid was given that name by the French chemist

Jean-Baptiste Dumas Jean Baptiste André Dumas (14 July 180010 April 1884) was a French chemist, best known for his works on organic analysis and synthesis, as well as the determination of atomic weights (relative atomic masses) and molecular weights by measuring v ...

in 1841. Its synthesis from

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it req ...

, and the correct determination of its formula, were accomplished during 1841. In 1799, French chemist Jean-Joseph Welter (1763–1852) produced picric acid by treating silk with nitric acid; he found that potassium picrate could explode. Not until 1830 did chemists think to use picric acid as an

. Before then, chemists assumed that only the

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 ...

s of picric acid were explosive, not the acid itself. In 1871

Hermann Sprengel Hermann Sprengel FRS (29 August 1834 – 14 January 1906) was a German-British chemist who discovered the explosive nature of picric acid in 1873, patented safety explosives and invented the mercurial air pump. Life He was born at Schille ...

proved it could be detonated and afterwards most

military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...

powers used picric acid as their main

high 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 exp ...

material. Picric acid was the first strongly explosive nitrated

widely considered suitable to withstand the shock of firing in conventional

artillery Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during siege ...

Nitroglycerine Nitroglycerin (NG), (alternative spelling of nitroglycerine) also known as trinitroglycerin (TNG), nitro, glyceryl trinitrate (GTN), or 1,2,3-trinitroxypropane, is a dense, colorless, oily, explosive liquid most commonly produced by nitrating ...

and

nitrocellulose Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...

(guncotton) were available earlier but shock sensitivity sometimes caused

detonation Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...

in an artillery barrel at the time of firing. In 1885, based on research of Hermann Sprengel, French chemist

Eugène Turpin François Eugène Turpin (30 September 1848 – 24 January 1927) was a French chemist involved in research of explosive materials. He lived in Colombes. Biography In 1881 Turpin proposed panclastites, a class of Sprengel explosives based on a mi ...

patented the use of pressed and cast picric acid in blasting charges and

artillery shell A shell, in a military context, is a projectile whose payload contains an explosive, incendiary, or other chemical filling. Originally it was called a bombshell, but "shell" has come to be unambiguous in a military context. Modern usage ...

s. In 1887 the French government adopted a mixture of picric acid and guncotton with the name Melinite. In 1888, Britain started manufacturing a very similar mixture in

Lydd Lydd is a town and electoral ward in Kent, England, lying on Romney Marsh. It is one of the larger settlements on the marsh, and the most southerly town in Kent. Lydd reached the height of its prosperity during the 13th century, when it was a co ...

, Kent, with the name Lyddite. Japan followed with an alternative stabilization approach known as

Shimose powder was a type of explosive shell-filling developed by the Japanese naval engineer (1860–1911). Shimose, born in Hiroshima Prefecture, graduated from Tokyo Imperial University and became one of Japan's earliest holders of a doctorate in enginee ...

which, instead of attempting to stabilize the material itself, instead removed its contact with metal by coating the inside of the shells with layers of ceramic and wax. In 1889, a mixture of ammonium cresylate with

trinitrocresol {{Short pages monitor

{{Authority control Explosive chemicals Nitrophenols Organic acids