urea urea urea names pronunciation urea /jʊəˈriːə/, carbamide /ˈkɑːrbəmaɪd/ preferred iupac name urea systematic iupac name carbonyl diamide other names carbamidecarbonyldiamidecarbonyldiaminediaminomethanaldiaminomethanone identifiers cas number 57-13-6 y 3d model (jsmol) interactive image beilstein reference 635724 chebi chebi:16199 y chembl chembl985 y chemspider 1143 y drugbank db03904 y echa infocard 100.000.286 e number e927b (glazing agents, ...) gmelin reference 1378 iuphar/bps 4539 kegg d00023 y pubchem cid 1176 rtecs number yr6250000 unii 8w8t17847w y comptox dashboard (epa) dtxsid4021426 inchi inchi=1s/ch4n2o/c2-1(3)4/h(h4,2,3,4) ykey: xsqukjjjfzcrtk-uhfffaoysa-n yinchi=1/ch4n2o/c2-1(3)4/h(h4,2,3,4)key: xsqukjjjfzcrtk-uhfffaoyaf smiles c(=o)(n)n properties chemical formula co(nh2)2 molar mass 60.06 g/mol appearance white solid density 1.32 g/cm3 melting point 133 to 135 °c (271 to 275 °f; 406 to 408 k) solubility in water 545 g/l (at 25 °c) solubility 500 g/l glycerol 50 g/l ethanol ~4 g/l acetonitrile basicity (pkb) 13.9 magnetic susceptibility (χ) −33.4·10−6 cm3/mol structure dipole moment 4.56 d thermochemistrycrc handbook std enthalpy offormation (δfh⦵298) −333.19 kj/mol gibbs free energy (δfg⦵) −197.15 kj/mol pharmacology atc code b05bc02 (who) d02ae01 (who) hazards ghs labelling: pictograms nfpa 704 (fire diamond) 1 1 0 flash point non-flammable lethal dose or concentration (ld, lc): ld50 (median dose) 8500 mg/kg (oral, rat) safety data sheet (sds) jt baker related compounds related ureas thioureahydroxycarbamide related compounds carbamide peroxideurea phosphateacetonecarbonic acidcarbonyl fluoride except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). y verify (what is yn ?) infobox references not to be confused with uric acid, urate, or urine. urea, also called carbamide, is an organic compound with chemical formula co(nh2)2. this amide has two amino groups (–nh2) joined by a carbonyl functional group (–c(=o)–). it is thus the simplest amide of carbamic acid. urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. urea is neo-latin, from french urée, from ancient greek οὖρον (oûron) 'urine', itself from proto-indo-european *h₂worsom. it is a colorless, odorless solid, highly soluble in water, and practically non-toxic (ld50 is 15 g/kg for rats). dissolved in water, it is neither acidic nor alkaline. the body uses it in many processes, most notably nitrogen excretion. the liver forms it by combining two ammonia molecules (nh3) with a carbon dioxide (co2) molecule in the urea cycle. urea is widely used in fertilizers as a source of nitrogen (n) and is an important raw material for the chemical industry. in 1828 friedrich wöhler discovered that urea can be produced from inorganic starting materials, which was an important conceptual milestone in chemistry. this showed for the first time that a substance previously known only as a byproduct of life could be synthesized in the laboratory without biological starting materials, thereby contradicting the widely held doctrine of vitalism, which stated that only living organisms could produce the chemicals of life. properties molecular and crystal structure the urea molecule is planar. in solid urea, the oxygen center is engaged in two n–h–o hydrogen bonds. the resulting dense and energetically favourable hydrogen-bond network is probably established at the cost of efficient molecular packing: the structure is quite open, the ribbons forming tunnels with square cross-section. the carbon in urea is described as sp2 hybridized, the c-n bonds have significant double bond character, and the carbonyl oxygen is basic compared to, say, formaldehyde. urea's high aqueous solubility reflects its ability to engage in extensive hydrogen bonding with water. by virtue of its tendency to form porous frameworks, urea has the ability to trap many organic compounds. in these so-called clathrates, the organic "guest" molecules are held in channels formed by interpenetrating helices composed of hydrogen-bonded urea molecules. as the helices are interconnected, all helices in a crystal must have the same molecular handedness. this is determined when the crystal is nucleated and can thus be forced by seeding. the resulting crystals have been used to separate racemic mixtures. reactions urea is basic. as such it is protonated readily. it is also a lewis base forming complexes of the type n+. urea reacts with malonic esters to make barbituric acids. decomposition molten urea decomposes into ammonium cyanate at about 152 °c, and into ammonia and isocyanic acid above 160 °c: co(nh2)2 → +− → nh3 + hnco heating above 160 °c yields biuret nh2conhconh2 and triuret nh2conhconhconh2 via reaction with isocyanic acid: co(nh2)2 + hnco → nh2conhconh2 nh2conhconh2 + hnco → nh2conhconhconh2 at higher temperatures it converts to a range of condensation products, including cyanuric acid (cnoh)3, guanidine hnc(nh2)2, and melamine. in aqueous solution, urea slowly equilibrates with ammonium cyanate. this hydrolysis cogenerates isocyanic acid, which can carbamylate proteins, in particular the n-terminal amino group and the side chain amino of lysine, and to a lesser extent the side chains of arginine and cysteine. each carbamylation event adds 43 daltons to the mass of the protein, which can be observed in protein mass spectrometery. for this reason, pure urea solutions should be freshly prepared and used, as aged solutions may develop a significant concentration of cyanate (20 mm in 8 m urea). dissolving urea in ultrapure water followed by removing ions (i.e. cyanate) with a mixed-bed ion-exchange resin and storing that solution at 4 °c is a recommended preparation procedure. however, cyanate will build back up to significant levels within a few days. alternatively, adding 25–50 mm ammonium chloride to a concentrated urea solution decreases formation of cyanate because of the common ion effect. analysis urea is readily quantified by a number of different methods, such as the diacetyl monoxime colorimetric method, and the berthelot reaction (after initial conversion of urea to ammonia via urease). these methods are amenable to high throughput instrumentation, such as automated flow injection analyzers and 96-well micro-plate spectrophotometers. related compounds ureas describes a class of chemical compounds that share the same functional group, a carbonyl group attached to two organic amine residues: r1r2n−c(=o)−nr3r4, where r1, r2, r3 and r4 groups are hydrogen (–h), organyl or other groups. examples include carbamide peroxide, allantoin, and hydantoin. ureas are closely related to biurets and related in structure to amides, carbamates, carbodiimides, and thiocarbamides. uses agriculture a plant in bangladesh that produces urea fertilizer. more than 90% of world industrial production of urea is destined for use as a nitrogen-release fertilizer. urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use. therefore, it has a low transportation cost per unit of nitrogen nutrient. the most common impurity of synthetic urea is biuret, which impairs plant growth. urea breaks down in the soil to give ammonium ions (nh+4). the ammonium is taken up by the plant through its roots. in some soils, the ammonium is oxidized by bacteria to give nitrate (no−3), which is also a nitrogen-rich plant nutrient. the loss of nitrogenous compounds to the atmosphere and runoff is wasteful and environmentally damaging so urea is sometimes modified to enhance the efficiency of its agricultural use. techniques to make controlled-release fertilizers that slow the release of nitrogen include the encapsulation of urea in an inert sealant, and conversion of urea into derivatives such as urea-formaldehyde compounds, which degrade into ammonia at a pace matching plants' nutritional requirements. resins urea is a raw material for the manufacture of urea-formaldehyde resins, used mainly in wood-based panels such as particleboard, fiberboard and plywood. explosives urea can be used to make urea nitrate, a high explosive that is used industrially and as part of some improvised explosive devices. automobile systems urea is used in selective non-catalytic reduction (sncr) and selective catalytic reduction (scr) reactions to reduce the nox pollutants in exhaust gases from combustion from diesel, dual fuel, and lean-burn natural gas engines. the bluetec system, for example, injects a water-based urea solution into the exhaust system. ammonia (nh3) first produced by the hydrolysis of urea reacts with nitrogen oxides (nox) and is converted into nitrogen gas (n2) and water within the catalytic converter. the conversion of noxious nox to innocuous n2 is described by the following simplified global equation: 4 no + 4 nh3 + o2 → 4 n2 + 6 h2o when urea is used, a pre-reaction (hydrolysis) occurs to first convert it to ammonia: co(nh2)2 + h2o → 2 nh3 + co2 being a solid highly soluble in water (545 g/l at 25 °c), urea is much easier and safer to handle and store than the more irritant, caustic and hazardous ammonia (nh3), so it is the reactant of choice. trucks and cars using these catalytic converters need to carry a supply of diesel exhaust fluid, also sold as adblue, a solution of urea in water. laboratory uses urea in concentrations up to 10 m is a powerful protein denaturant as it disrupts the noncovalent bonds in the proteins. this property can be exploited to increase the solubility of some proteins. a mixture of urea and choline chloride is used as a deep eutectic solvent (des), a substance similar to ionic liquid. when used in a deep eutectic solvent, urea gradually denatures the proteins that are solubilized. urea can in principle serve as a hydrogen source for subsequent power generation in fuel cells. urea present in urine/wastewater can be used directly (though bacteria normally quickly degrade urea). producing hydrogen by electrolysis of urea solution occurs at a lower voltage (0.37 v) and thus consumes less energy than the electrolysis of water (1.2 v). urea in concentrations up to 8 m can be used to make fixed brain tissue transparent to visible light while still preserving fluorescent signals from labeled cells. this allows for much deeper imaging of neuronal processes than previously obtainable using conventional one photon or two photon confocal microscopes. medical use urea-containing creams are used as topical dermatological products to promote rehydration of the skin. urea 40% is indicated for psoriasis, xerosis, onychomycosis, ichthyosis, eczema, keratosis, keratoderma, corns, and calluses. if covered by an occlusive dressing, 40% urea preparations may also be used for nonsurgical debridement of nails. urea 40% "dissolves the intercellular matrix" of the nail plate. only diseased or dystrophic nails are removed, as there is no effect on healthy portions of the nail. this drug (as carbamide peroxide) is also used as an earwax removal aid. urea has also been studied as a diuretic. it was first used by dr. w. friedrich in 1892. in a 2010 study of icu patients, urea was used to treat euvolemic hyponatremia and was found safe, inexpensive, and simple. like saline, urea has been injected into the uterus to induce abortion, although this method is no longer in widespread use. the blood urea nitrogen (bun) test is a measure of the amount of nitrogen in the blood that comes from urea. it is used as a marker of renal function, though it is inferior to other markers such as creatinine because blood urea levels are influenced by other factors such as diet, dehydration, and liver function. urea has also been studied as an excipient in drug-coated balloon (dcb) coating formulation to enhance local drug delivery to stenotic blood vessels. urea, when used as an excipient in small doses (~3 μg/mm2) to coat dcb surface was found to form crystals that increase drug transfer without adverse toxic effects on vascular endothelial cells. urea labeled with carbon-14 or carbon-13 is used in the urea breath test, which is used to detect the presence of the bacterium helicobacter pylori (h. pylori) in the stomach and duodenum of humans, associated with peptic ulcers. the test detects the characteristic enzyme urease, produced by h. pylori, by a reaction that produces ammonia from urea. this increases the ph (reduces the acidity) of the stomach environment around the bacteria. similar bacteria species to h. pylori can be identified by the same test in animals such as apes, dogs, and cats (including big cats). miscellaneous uses an ingredient in diesel exhaust fluid (def), which is 32.5% urea and 67.5% de-ionized water. def is sprayed into the exhaust stream of diesel vehicles to break down dangerous nox emissions into harmless nitrogen and water. a component of animal feed, providing a relatively cheap source of nitrogen to promote growth a non-corroding alternative to rock salt for road de-icing. it is often the main ingredient of pet friendly salt substitutes although it is less effective than traditional rock salt or calcium chloride. a main ingredient in hair