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31-489: With a nominal weight of 500 lb (230 kg), it is one of the smallest bombs in current service, and one of the most common air-dropped weapons in the world. Although the Mk82's nominal weight is 500 lb (230 kg), its actual weight varies depending on its configuration, from 510 to 570 lb (230 to 260 kg). It is a streamlined steel casing containing 192 lb (87 kg) of Tritonal high explosive. The Mk82

62-455: A characteristic red color forms. With a calibrating glucose solution, the red color can be used to measure the glucose levels added. This is known as the Lewis and Benedict method of measuring glucose. Much less commonly, wet picric acid has been used as a skin dye, or temporary branding agent. It reacts with proteins in the skin to give a dark brown color that may last as long as a month. During

93-501: A cheaper substitute for Torpex and HBX under UWE designation (UnderWater Explosive) before it turned out Allies could produce enough RDX to cover all naval requirements late in WWII. Picric acid Picric acid is an organic compound with the formula (O 2 N) 3 C 6 H 2 OH. Its IUPAC name is 2,4,6-trinitrophenol ( TNP ). The name "picric" comes from Greek : πικρός ( pikros ), meaning "bitter", due to its bitter taste. It

124-478: A layer of water , rendering it safe. Glass or plastic bottles are required, as picric acid can easily form metal picrate salts that are even more sensitive and hazardous than the acid itself. Industrially, picric acid is especially hazardous because it is volatile and slowly sublimes even at room temperature. Over time, the buildup of picrates on exposed metal surfaces can constitute an explosion hazard. Picric acid gauze, if found in antique first aid kits, presents

155-487: A minor redesign to allow it to meet the insensitive munitions requirements set by Congress. According to a test report conducted by the United States Navy 's Weapon Systems Explosives Safety Review Board established in the wake of the 1967 USS Forrestal fire , the cooking off time for a Mk82 is approximately 2 minutes 30 seconds . More than 4,500 GBU-12/Mk82 laser-guided bombs were dropped on Iraq during

186-457: A safety hazard because picric acid of that vintage (60–90 years old) will have become crystallized and unstable, and may have formed metal picrates from long storage in a metal first aid case. Bomb disposal units are often called to dispose of picric acid if it has dried out. In the United States there was an effort to remove dried picric acid containers from high school laboratories during

217-724: Is offered with a variety of fin kits, fuzes , and retarders for different purposes. The Mk82 is the warhead for the GBU-12 laser-guided bombs and for the GBU-38 JDAM. Currently only the General Dynamics plant in Garland, Texas and Nitro-Chem in Bydgoszcz , Poland are Department of Defense-certified to manufacture bombs for the US Armed Forces. The Mk82 is currently undergoing

248-434: Is one of the most acidic phenols . Like other strongly nitrated organic compounds, picric acid is an explosive , which is its primary use. It has also been used as medicine ( antiseptic , burn treatments) and as a dye. Picric acid was probably first mentioned in the alchemical writings of Johann Rudolf Glauber . Initially, it was made by nitrating substances such as animal horn, silk , indigo , and natural resin ,

279-461: Is released, slowing the bomb by increasing drag, thus allowing the delivery aircraft to safely pass over the target before the bomb hits it. Tritonal Tritonal is a mixture of 80% TNT and 20% aluminium powder , used in several types of ordnance such as air-dropped bombs . The aluminium increases the total heat output and hence impulse of the TNT ;– the length of time during which

310-434: Is still used to etch magnesium alloys , such as AZ31. Bouin solution is a common picric-acid–containing fixative solution used for histology specimens. It improves the staining of acid dyes, but it can also result in hydrolysis of any DNA in the sample. Picric acid is used in the preparation of Picrosirius red , a histological stain for collagen . Clinical chemistry laboratory testing utilizes picric acid for

341-495: The Jaffe reaction to test for creatinine . It forms a colored complex that can be measured using spectroscopy. Picric acid forms red isopurpurate with hydrogen cyanide (HCN). By photometric measurement of the resulting dye, picric acid can be used to quantify hydrogen cyanide. During the early 20th century, picric acid was used to measure blood glucose levels. When glucose, picric acid and sodium carbonate are combined and heated,

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372-569: The Persian Gulf War . France requested 1,200 Mk82s in 2010 to Société des Ateliers Mécaniques de Pont-sur-Sambre (SAMP) which builds Mk82s under license. Saudi Arabia requested 8,000 Mk82s in 2015, along with guidance kits and other weapons. In August, 2018, a Mark 82 bomb was used for Saudi Arabia's Dahyan air strike in Yemen . Munitions experts confirmed that the numbers on it identified Lockheed Martin as its maker and that this particular Mk82

403-511: The Western Front during World War I . Picric acid has been used for many years by fly tyers to dye mole skins and feathers a dark olive green for use as fishing lures. Its popularity has been tempered by its toxic nature. Modern safety precautions recommend storing picric acid wet, to minimize the danger of explosion. Dry picric acid is relatively sensitive to shock and friction , so laboratories that use it store it in bottles under

434-598: The salts of picric acid were explosive, not the acid itself. In 1871 Hermann Sprengel proved it could be detonated and afterwards most military powers used picric acid as their main high explosive material. A full synthesis was later found by Leonid Valerieovich Kozakov. Picric acid was the first strongly explosive nitrated organic compound widely considered suitable to withstand the shock of firing in conventional artillery . Nitroglycerine and nitrocellulose (guncotton) were available earlier, but shock sensitivity sometimes caused detonation in an artillery barrel at

465-478: The sulfonic acid group is displaced. The reaction is highly exothermic , and careful temperature control is required. Synthesis routes that nitrate aspirin or salicylic acid can also be used to mitigate tar formation. Carbon dioxide is lost from the former via decarboxylation , while both acetic acid and carbon dioxide are lost from the latter. Another method of picric acid synthesis is direct nitration of 2,4-dinitrophenol with nitric acid. It crystallizes in

496-478: The Allies. At the time, phenol was obtained from coal as a co-product of coke ovens and the manufacture of gas for gas lighting . Laclede Gas reports being asked to expand production of phenol (and toluene ) to assist the war effort. Both Monsanto and Dow Chemical began manufacturing synthetic phenol in 1915, with Dow being the main producer. Dow describes picric acid as "the main battlefield explosive used by

527-505: The French. Large amounts [of phenol] also went to Japan, where it was made into picric acid sold to the Russians." Thomas Edison needed phenol to manufacture phonograph records. He responded by undertaking production of phenol at his Silver Lake, New Jersey , facility using processes developed by his chemists. He built two plants with a capacity of six tons of phenol per day. Production began

558-463: The blast and fragmentation effects of its own munitions since the aircraft and ordnance arrive at the target almost simultaneously. To address this issue, the standard Mk82 General-Purpose bomb can be fitted with a special high-drag tail fin unit. In this configuration, it is referred to as the Mk82 Snake Eye. The tail unit has four folded fins that spring open into a cruciform shape when the bomb

589-431: The blast wave is positive. Tritonal is approximately 18% more powerful than TNT alone. The 87  kg of tritonal in a Mark 82 bomb has the potential to produce approximately 863  MJ of energy when detonated. This implies a specific energy of approximately 9 MJ/kg, compared to ~4 MJ/kg for TNT. TNT was first prepared by Julius Wilbrand in 1863. Germany began manufacturing TNT in 1891 and aluminium

620-500: The early 20th century, picric acid was stocked in pharmacies as an antiseptic and as a treatment for burns , malaria , herpes , and smallpox . Picric-acid–soaked gauze was commonly stocked in first aid kits from that period as a burn treatment. It was notably used for the treatment of burns suffered by victims of the Hindenburg disaster in 1937. Picric acid was used as a treatment for trench foot suffered by soldiers stationed on

651-640: The feedstock). Picramide, formed by aminating picric acid (typically beginning with Dunnite), can be further aminated to produce the very stable explosive TATB . It has found some use in organic chemistry for the preparation of crystalline salts of organic bases (picrates) for the purpose of identification and characterization. In metallurgy , a 4% picric acid in ethanol etch, termed "picral", has been commonly used in optical metallography to reveal prior austenite grain boundaries in ferritic steels. The hazards associated with picric acid have meant it has largely been replaced with other chemical etchants. However, it

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682-603: The first week of September, one month after hostilities began in Europe. He built two plants to produce the raw material benzene at Johnstown, Pennsylvania , and Bessemer, Alabama , replacing supplies previously from Germany. Edison manufactured aniline dyes , which had previously been supplied by the German dye trust . Other wartime products included xylene , p-phenylenediamine , shellac , and pyrophyllite . Wartime shortages made these ventures profitable. In 1915, his production capacity

713-488: The material itself, removed its contact with metal by coating the inside of the shells with layer(s) of resin and wax. In 1889, a mixture of ammonium cresylate with trinitrocresol , or an ammonium salt of trinitrocresol, started to be manufactured with the name Ecrasite in Austria-Hungary . By 1894 Russia was manufacturing artillery shells filled with picric acid. Ammonium picrate (known as Dunnite or explosive D )

744-416: The orthorhombic space group Pca 2 1 with a = 9.13 Å, b = 18.69 Å, c = 9.79 Å and α = β = γ = 90°. By far the greatest use of picric acid has been in ammunitions and explosives. Explosive D , also known as Dunnite, is the ammonium salt of picric acid. Dunnite is more powerful but less stable than the more common explosive TNT (which is produced in a similar process to picric acid but with toluene as

775-677: The synthesis from indigo first being performed by Peter Woulfe in 1771. The German chemist Justus von Liebig had named picric acid Kohlenstickstoffsäure (rendered in French as acide carboazotique ). Picric acid was given that name by the French chemist Jean-Baptiste Dumas in 1841. Its synthesis from phenol , 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 explosive . Before then, chemists assumed that only

806-574: The time of firing. In 1885, based on research of Hermann Sprengel, French chemist Eugène Turpin patented the use of pressed and cast picric acid in blasting charges and artillery shells . 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 , Kent, with the name Lyddite . Japan followed with an alternative stabilization approach known as Shimose powder which, instead of attempting to stabilize

837-667: Was a Paveway, a laser-guided bomb. Along with the heavier Mark 84 bombs, Mark 82 bombs were also supplied for the Israel-Hamas war in Gaza . In July 2024, the Biden administration resumed shipments of the 500-pound bombs to Israel, which were halted in May due to concerns about the high number of civilian casualties in Gaza . In low-level bombing, it is possible for the delivering aircraft to sustain damage from

868-508: Was first mixed with TNT in 1899 to produce an explosive compound. In 1902, the German Army began to use TNT, replacing picric acid , and in 1912, the US Army also started to use TNT. TNT production was limited by the availability of toluene which came from coal tar. Therefore, mixtures of TNT with other compounds became widespread to relieve the shortage of TNT. Modern tritonal was developed as

899-488: Was fully committed by midyear. The aromatic ring of phenol is activated towards electrophilic substitution reactions, and attempted nitration of phenol, even with dilute nitric acid, results in the formation of high molecular weight tars. In order to minimize these side reactions, anhydrous phenol is sulfonated with fuming sulfuric acid , and the resulting sulfonic acid is then nitrated with concentrated nitric acid . During this reaction, nitro groups are introduced, and

930-601: Was less readily available than phenol, and TNT is less powerful than picric acid, but the improved safety of munitions manufacturing and storage caused the replacement of picric acid by TNT for most military purposes between the World Wars. Efforts to control the availability of phenol , the precursor to picric acid, emphasize its importance in World War I . Germans are reported to have bought US supplies of phenol and converted it to acetylsalicylic acid ( aspirin ) to keep it from

961-750: Was used by the United States beginning in 1906. However, shells filled with picric acid become unstable if the compound reacts with the metal shell or fuze casings to form metal picrates which are more sensitive than the parent phenol. The sensitivity of picric acid was demonstrated by the Halifax Explosion . Picric acid was used in the Battle of Omdurman , the Second Boer War , the Russo-Japanese War , and World War I . Germany began filling artillery shells with trinitrotoluene (TNT) in 1902. Toluene

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