Urea
IUPAC name	Diaminomethanal
Other names	Carbamide
Identifiers
CAS number	[57-13-6]
SMILES	NC(=O)N
Properties
Molecular formula	(NH2)2CO
Molar mass	60.07 g/mol
Appearance	white odourless solid
Density	1.33·10³ kg/m³[1], solid
Melting point	132.7 °C (406 K) decomposes Structure of Urea, created with ChemSketch. ... Image File history File links Download high-resolution version (1100x1069, 220 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Urea ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. ... A chemical formula is an easy way of expressing information about the atoms that constitute a particular chemical compound. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... For other uses, see Density (disambiguation). ... The melting point of a solid is the temperature range at which it changes state from solid to liquid. ...
Boiling point	n.a. Italic text This article is about the boiling point of liquids. ...
Solubility in water	108 g/100 ml (20 °C) 167 g/100 ml (40 °C) 251 g/100 ml (60 °C) 400 g/100 ml (80 °C) 733 g/100 ml (100 °C)
Acidity (pKa)	26.9
Basicity (pKb)	13.82
Structure
Dipole moment	4.56 p/D
Hazards
MSDS	ScienceLab.com
Main hazards	Toxic
NFPA 704	1 2
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Urea is an organic compound with the chemical formula (NH₂)₂CO. Solubility is a chemical property referring to the ability for a given substance, the solute, to dissolve in a solvent. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... An acid dissociation constant, denoted by Ka, is an equilibrium constant for the dissociation of a weak acid. ... An acid dissociation constant, denoted by Ka, is an equilibrium constant for the dissociation of a weak acid. ... The Earths magnetic field, which is approximately a dipole. ... The debye (symbol: D) is a non-SI and non-CGS unit of electrical dipole moment. ... This page meets Wikipedias criteria for speedy deletion. ... The examples and perspective in this article or section may not represent a worldwide view. ... NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ... Image File history File links NFPA_704. ... The plimsoll symbol as used in shipping In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals exactly). ... Benzene is the simplest of the arenes, a family of organic compounds An organic compound is any member of a large class of chemical compounds whose molecules contain carbon. ... A chemical formula is an easy way of expressing information about the atoms that constitute a particular chemical compound. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... This article is about the chemistry of hydrogen. ... For other uses, see Carbon (disambiguation). ... This article is about the chemical element and its most stable form, or dioxygen. ...

Urea is also known by the International Nonproprietary Name (rINN) carbamide, as established by the World Health Organization. For example, the medicinal compound hydroxyurea (old British Approved Name) is now hydroxycarbamide. Other names include carbamide resin, isourea, carbonyl diamide, and carbonyldiamine. An International Nonproprietary Name (INN) is the official non-proprietary or generic name given to a pharmaceutical substance, as designated by the World Health Organization. ... WHO redirects here. ... Hydroxyurea or hydroxycarbamide (brand names include Hydrea®) is an antineoplastic drug used in hematological malignancies. ...

Discovery

It was the first organic compound to be artificially synthesized from inorganic starting materials, in 1828 by Friedrich Wöhler, who prepared it by the reaction of potassium cyanate with ammonium sulfate. Although Wöhler was attempting to prepare ammonium cyanate, by forming urea, he inadvertently discredited vitalism, the theory that the chemicals of living organisms are fundamentally different from inanimate matter, thus starting the discipline of organic chemistry. Year 1828 (MDCCCXXVIII) was a leap year starting on Tuesday (link will display the full calendar) of the Gregorian Calendar (or a leap year starting on Thursday of the 12-day slower Julian calendar). ... Friedrich Wöhler (July 31, 1800 - September 23, 1882) was a German chemist, best-known for his synthesis of urea, but also the first to isolate several of the elements. ... Potassium cyanate or potassium isocyanate is an inorganic compound and the potassium salt of cyanic acid with the chemical formula of KOCN (also: KCNO). ... Ammonium sulphate, [NH4]2[SO4] contains 21% nitrogen as ammonia and 24% sulfur as sulfate. ... Vitalism is the doctrine that vital forces are active in living organisms, so that life cannot be explained solely by mechanism. ... Organic chemistry is a specific discipline within chemistry which involves the scientific study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of chemical compounds consisting primarily of carbon and hydrogen, which may contain any number of other elements, including nitrogen, oxygen, the halogens as...

This discovery prompted Wöhler to write triumphantly to Berzelius:

"I must tell you that I can make urea without the use of kidneys, either man or dog. Ammonium cyanate is urea."

It is found in mammalian and amphibian urine as well as in some fish. Birds and reptiles excrete uric acid, comprising a different form of nitrogen metabolism that requires less water. Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria For the folk-rock band see The Mammals. ... For other uses, see Amphibian (disambiguation). ... This article is about the urine of animals generally. ... For other uses, see Fish (disambiguation). ... For other uses, see Bird (disambiguation). ... Reptilia redirects here. ... Uric acid (or urate) is an organic compound of carbon, nitrogen, oxygen and hydrogen with the formula C5H4N4O3. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Structure of the coenzyme adenosine triphosphate, a central intermediate in energy metabolism. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ...

Structure

Urea is highly soluble in water and is, therefore, an efficient way for the human body to expel excess nitrogen. Due to extensive hydrogen bonding with water (up to six hydrogen bonds may form - two from the oxygen atom and one from each hydrogen), it is very soluble, and, thus, is also a good fertilizer.

The urea molecule is planar and retains its full molecular point symmetry, due to conjugation of one of each nitrogen's P orbital to the carbonyl double bond. Each carbonyl oxygen atom accepts four N-H-O hydrogen bonds,^{[citation needed]} a very unusual feature for such a bond type. This 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.

Physiology

Endogenous production

Main article: urea cycle

The individual atoms that make up a urea molecule come from carbon dioxide, water, aspartate, and ammonia in a metabolic pathway known as the urea cycle, an anabolic process. Organisms synthesize urea from ammonia because ammonia (a common metabolic waste product) raises pH in cells to toxic levels. Therefore, urea synthesis is necessary even though it costs energy to produce. Urea is neither acidic nor basic, so it is a perfect vehicle for getting rid of nitrogen waste. Urea production occurs in the liver and is regulated by N-acetylglutamate. The reactions of the urea cycle. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Aspartic acid, also known as aspartate, the name of its anion, is one of the 20 natural proteinogenic amino acids which are the building blocks of proteins. ... For other uses, see Ammonia (disambiguation). ... In biochemistry, a metabolic pathway is a series of chemical reactions occurring within a cell. ... The reactions of the urea cycle. ... Anabolism is the metabolic process that builds larger molecules from smaller ones. ... Structure of the coenzyme adenosine triphosphate, a central intermediate in energy metabolism. ... For alternative meanings see acid (disambiguation). ... Acids and bases: Acid-base extraction Acid-base reaction Acid dissociation constant Acidity function Buffer solutions pH Proton affinity Self-ionization of water Acids: Lewis acids Mineral acids Organic acids Strong acids Superacids Weak acids Bases: Lewis bases Organic bases Strong bases Superbases Non-nucleophilic bases Weak bases edit In... The liver is the largest internal organ in the human body, and is an organ present in vertebrates and some other animals. ... N-acetylglutamate is a coenzyme which allosterically activates carbamoyl phosphate synthetase I, which is the mitochondrial enzyme that catalyzes the first committed step of the urea cycle. ...

In this cycle, amino groups donated by ammonia and L-aspartate are converted to urea, while L-ornithine, citrulline, L-argininosuccinate, and L-arginine act as intermediates. In chemistry, especially in organic chemistry and biochemistry, an amino group is an ammonia-like functional group. ... For other uses, see Ammonia (disambiguation). ... Aspartic acid, also known as aspartate, the name of its anion, is one of the 20 natural proteinogenic amino acids which are the building blocks of proteins. ... Ornithine is an amino acid, whose structure is: NH2-CH2-CH2-CH2-CHNH2-COOH Ornithine is one of the products of the action of the enzyme arginase on L-arginine, creating urea. ... The chemical compound citrulline is an α-amino acid (AA). ... Arginosuccinic acid is a chemical compound that belongs to the class of the amino acids. ... Arginine (abbreviated as Arg or R)[1] is an α-amino acid. ...

Function

In humans

Urea is, in essence, a waste product. However, it also plays a very important role in that it helps set up the countercurrent system in the nephrons. The countercurrent system in the nephrons allows for reabsorption of water and critical ions. Urea is reabsorbed in the inner medullary collecting ducts of the nephrons^[2], thus raising the osmolarity in the medullary interstitium surrounding the thin ascending limb of the Loop of Henle. The greater the osmolarity of the medullary interstitium surrounding the thin ascending Loop of Henle, the more water will be reabsorbed out of the renal tubule back into the interstitium (and thus back into the body). Some of the urea from the meduallary interstitium that helped set up the Countercurrent System will also flow back into the tubule, through urea transporter 2, into the thin ascending limb of the loop of Henle, through the collecting ducts, and eventually out of the body as a component of urine. Countercurrent exchange is a mechanism used to transfer some component of a fluid from one flowing current of fluid to another across a permeable barrier between them. ... Nephron of the kidney A nephron is the basic structural and functional unit of the kidney. ... Osmolality, in biology and chemistry, is a measure of moles of solute per kg of water. ... Interstitial is a generic term for referring to the space between other structures or objects. ... In the kidney, the loop of Henle is the portion of the nephron that leads from the proximal convoluted tubule to the distal convoluted tubule. ...

It is dissolved in blood (in a concentration of 2.5 - 7.5 mmol/liter) and excreted by the kidney as a component of urine. In addition, a small amount of urea is excreted (along with sodium chloride and water) in sweat. This article is about the urine of animals generally. ... R-phrases 36 S-phrases none Flash point Non-flammable Related Compounds Other anions NaF, NaBr, NaI Other cations LiCl, KCl, RbCl, CsCl, MgCl2, CaCl2 Related salts Sodium acetate Supplementary data page Structure and properties n, εr, etc. ... SWEAT is an OLN/TSN show hosted by Julie Zwillich that aired in 2003-2004. ...

Regulation

Main article: renal urea handling

Control of urea by antidiuretic hormone allows the body to create hyperosmotic urine (urine that has more ions in it--is "more concentrated"--than that same person's blood plasma). Preventing the loss of water in this manner is important if the person's body needs to save water in order to maintain a suitable blood pressure or (more likely,) in order to maintain a suitable concentration of sodium ions in the blood plasma. Antidiuretic hormone (ADH), or arginine vasopressin (AVP), is a peptide hormone produced by the hypothalamus, and stored in the posterior part of the pituitary gland. ... Hyperosmotic ...a term describing organisms with body fluids with a lower concentration of water and higher solute concentration than the external environment. ... Blood plasma is the liquid component of blood, in which the blood cells are suspended. ... A sphygmomanometer, a device used for measuring arterial pressure. ... For sodium in the diet, see Salt. ...

Non-humans

Most organisms have to deal with the excretion of nitrogen waste originating from protein and amino acid catabolism. In aquatic organisms the most common form of nitrogen waste is ammonia, while land-dwelling organisms convert the toxic ammonia to either urea or uric acid. In general, birds and saurian reptiles excrete uric acid, whereas the remaining species, including mammals, excrete urea. It is noteworthy that tadpoles excrete ammonia, and shift to urea production during metamorphosis. In veterinary medicine, Dalmatian breeds of dogs are noteworthy in that they excrete nitrogen in the form of uric acid in the urine rather than in the urea form. This is due to a defect in one of the genes controlling expression of the conversion enzymes in the urea cycle. Domains and Kingdoms Nanobes Acytota Cytota Bacteria Neomura Archaea Eukaryota Bikonta Apusozoa Rhizaria Excavata Archaeplastida Rhodophyta Glaucophyta Plantae Heterokontophyta Haptophyta Cryptophyta Alveolata Unikonta Amoebozoa Opisthokonta Choanozoa Fungi Animalia An ericoid mycorrhizal fungus Life on Earth redirects here. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... This article is about the class of chemicals. ... Anabolism is the aspect of metabolism that contributes to growth. ... Various species of reef fish in the Hawaiian Islands. ... Uric acid (or urate) is an organic compound of carbon, nitrogen, oxygen and hydrogen with the formula C5H4N4O3. ... For other uses, see Bird (disambiguation). ... The sarrukh are a fictitious race of reptilian humanoids in the Forgotten Realms setting of Dungeons & Dragons. ... Reptilia redirects here. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria For the folk-rock band see The Mammals. ... For other uses, see Tadpole (disambiguation). ... A Pieris rapae larva An older Pieris rapae larva A Pieris rapae pupa A Pieris rapae adult Metamorphosis is a process in biology by which an individual physically develops after birth or hatching, and involves significant change in form as well as growth and differentiation. ... Veterinary medicine is the application of medical, diagnostic, and therapeutic principles to companion, domestic, exotic, wildlife, and production animals. ... This article needs additional references or sources for verification. ... For other uses, see Gene (disambiguation). ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ...

Despite the generalization above, the pathway has been documented not only in mammals and amphibians but in many other organisms as well, including birds, invertebrates, insects, plants, yeast, fungi, and even microorganisms. Invertebrate is an English word that describes any animal without a spinal column. ... Orders Subclass Apterygota Archaeognatha (bristletails) Thysanura (silverfish) Subclass Pterygota Infraclass Paleoptera (Probably paraphyletic) Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Superorder Exopterygota Grylloblattodea (ice-crawlers) Mantophasmatodea (gladiators) Plecoptera (stoneflies) Embioptera (webspinners) Zoraptera (angel insects) Dermaptera (earwigs) Orthoptera (grasshoppers, etc) Phasmatodea (stick insects) Blattodea (cockroaches) Isoptera (termites) Mantodea (mantids) Psocoptera... For other uses, see Plant (disambiguation). ... Typical divisions Ascomycota (sac fungi) Saccharomycotina (true yeasts) Taphrinomycotina Schizosaccharomycetes (fission yeasts) Basidiomycota (club fungi) Urediniomycetes Sporidiales Yeasts are a growth form of eukaryotic micro organisms classified in the kingdom Fungi, with about 1,500 species described;[1] they dominate fungal diversity in the oceans. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... A cluster of Escherichia coli bacteria magnified 10,000 times. ...

Hazards

Urea can be irritating to skin and eyes. Too high concentrations in the blood can cause damage to organs of the body. Low concentrations of urea such as in urine are not dangerous. This article is about the urine of animals generally. ...

It has been found that urea can cause algal blooms to produce toxins, and urea in runoff from fertilizers may play a role in the increase of toxic blooms.^[3] Algal blooms can present problems for ecosystems and human society An algal bloom or marine bloom or water bloom is a rapid increase in the population of algae in an aquatic system. ...

Repeated or prolonged contact with urea in fertilizer form on the skin may cause dermatitis. The substance also irritates the eyes, the skin, and the respiratory tract. The substance decomposes on heating above melting point, producing toxic gases, and reacts violently with strong oxidants, nitrites, inorganic chlorides, chlorites and perchlorates, causing fire and explosion hazard

Synthetic production

Urea is a nitrogen-containing chemical product that is produced on a scale of some 100,000,000 tons per year worldwide.

For use in industry, urea is produced from synthetic ammonia and carbon dioxide. Urea can be produced as prills, granules, flakes, pellets, crystals, and solutions. For other uses, see Ammonia (disambiguation). ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Prill is a dry pellet form of the explosive ANFO. Categories: Stub ... Granule is a generic term used for a small particle or grain. ...

More than 90% of world production is destined for use as a fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use (46.7%). Therefore, it has the lowest transportation costs per unit of nitrogen nutrient. Spreading manure, an organic fertilizer Fertilizers (also spelled fertilisers) are compounds given to plants to promote growth; they are usually applied either through the soil, for uptake by plant roots, or by foliar feeding, for uptake through leaves. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... A nutrient is a substance used in an organisms metabolism which must be taken in from the environment. ...

Urea is highly soluble in water and is, therefore, also very suitable for use in fertilizer solutions (in combination with ammonium nitrate: UAN), e.g., in 'foliar feed' fertilizers. Related Compounds Other anions Ammonium nitrite; ammonium perchlorate Other cations Sodium nitrate; potassium nitrate; hydroxylammonium nitrate Related compounds Nitrous oxide Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references The chemical compound ammonium nitrate, the nitrate of... United American Nurses (UAN) is an American union affiliated with the American Nurses Association (ANA) and the AFL-CIO. Unlike other unions that some American nurses belong to, such as the Service Employees International Union, the UAN represents only registered nurses (RNs). ...

Solid urea is marketed as prills or granules. The advantage of prills is that, in general, they can be produced more cheaply than granules, which, because of their narrower particle size distribution, have an advantage over prills if applied mechanically to the soil. Properties such as impact strength, crushing strength, and free-flowing behaviour are, in particular, important in product handling, storage, and bulk transportation. Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland For other uses, see Soil (disambiguation). ...

Commercial production

Urea is commercially produced from two raw materials, ammonia, and carbon dioxide. Large quantities of carbon dioxide are produced during the manufacture of ammonia from coal or from hydrocarbons such as natural gas and petroleum-derived raw materials. This allows direct synthesis of urea from these raw materials. For other uses, see Ammonia (disambiguation). ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... In chemistry, a hydrocarbon is a cleaning solution consisting only of carbon (C) and hydrogen (H). ...

The production of urea from ammonia and carbon dioxide takes place in an equilibrium reaction, with incomplete conversion of the reactants. The various urea processes are characterized by the conditions under which urea formation takes place and the way in which unconverted reactants are further processed. Chemical equilibrium is the state in which a chemical reaction proceeds at the same rate as its reverse reaction; the rates of the forward and reverse reactions are equal, and the concentration of the reactants and products stop changing. ...

Unconverted reactants can be used for the manufacture of other products, for example ammonium nitrate or sulfate, or they can be recycled for complete conversion to urea in a total-recycle process. Related Compounds Other anions Ammonium nitrite; ammonium perchlorate Other cations Sodium nitrate; potassium nitrate; hydroxylammonium nitrate Related compounds Nitrous oxide Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references The chemical compound ammonium nitrate, the nitrate of... The sulfate anion, SO42− The structure and bonding of the sulfate ion In inorganic chemistry, a sulfate (IUPAC-recommended spelling; also sulphate in British English) is a salt of sulfuric acid. ...

Two principal reactions take place in the formation of urea from ammonia and carbon dioxide. The first reaction is exothermic: For other uses, see Ammonia (disambiguation). ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ...

2 NH₃ + CO₂ → H₂N-COONH₄ (ammonium carbamate)

Whereas the second reaction is endothermic:

H₂N-COONH₄ → (NH₂)₂CO + H₂O

Both reactions combined are exothermic.

The process, developed in 1922, is also called the Bosch-Meiser urea process after its discoverers.

Uses

Agricultural use

Urea is used as a nitrogen-release fertilizer, as it hydrolyses back to ammonia and carbon dioxide, but its most common impurity, biuret, must be present at less than 2%, as it impairs plant growth. It is also used in many multi-component solid fertilizer formulations. Its action of nitrogen release is due to the conditions favouring the reagent side of the equilibriums, which produce urea. Hydrolysis is a chemical reaction or process in which a molecule is split into two parts by reacting with a molecule of water, which has the chemical formula H2O. One of the parts gets an OH- from the water molecule and the other part gets an H+ from the water. ... Biuret is a chemical compound with the chemical formula C2O2N3H5. ...

Urea is usually spread at rates of between 40 and 300 kg/ha, but actual spreading rates will vary according to farm type and region. It is better to make several small to medium applications at intervals to minimise leaching losses and increase efficient use of the N applied, compared with single heavy applications. During summer, urea should be spread just before, or during rain to reduce possible losses from volatilisation (process wherein nitrogen is lost to the atmosphere as ammonia gas). Urea should not be mixed for any length of time with other fertilizers, as problems of physical quality may result.

Because of the high nitrogen concentration in urea, it is very important to achieve an even spread. The application equipment must be correctly calibrated and properly used. Drilling must not occur on contact with or close to seed, due to the risk of germination damage. Urea dissolves in water for application as a spray or through irrigation systems.

In grain and cotton crops, urea is often applied at the time of the last cultivation before planting. It should be applied into or be incorporated into the soil. In high rainfall areas and on sandy soils (where nitrogen can be lost through leaching) and where good in-season rainfall is expected, urea can be side- or top-dressed during the growing season. Top-dressing is also popular on pasture and forage crops. In cultivating sugarcane, urea is side-dressed after planting, and applied to each ratoon crop.

In irrigated crops, urea can be applied dry to the soil, or dissolved and applied through the irrigation water. Urea will dissolve in its own weight in water, but it becomes increasingly difficult to dissolve as the concentration increases. Dissolving urea in water is endothermic, causing the temperature of the solution to fall when urea dissolves.

As a practical guide, when preparing urea solutions for fertigation (injection into irrigation lines), dissolve no more than 30 kg urea per 100 L water. Fertigation is the application of fertilizers, soil amendments, or other water soluble products through an irrigation system. ...

In foliar sprays, urea concentrations of 0.5% – 2.0% are often used in horticultural crops. As urea sprays may damage crop foliage, specific advice should be sought before use. Low-biuret grades of urea should be used if urea sprays are to be applied regularly or to sensitive horticultural crops. Biuret is a chemical compound with the chemical formula C2O2N3H5. ...

Storage of urea fertilizer

Like most nitrogen products, urea absorbs moisture from the atmosphere. Therefore it should be stored either in closed/sealed bags on pallets, or, if stored in bulk, under cover with a tarpaulin. As with most solid fertilizers, it should also be stored in a cool, dry, well-ventilated area.

Industrial use

Urea has the ability to form 'loose compounds', called clathrates, with many organic compounds. The organic compounds are held in channels formed by interpenetrating helices comprising of hydrogen-bonded urea molecules. This behaviour can be used to separate mixtures, and has been used in the production of aviation fuel and lubricating oils. As the helices are interconnected, all helices in a crystal must have the same 'handedness'. This is determined when the crystal is nucleated and can thus be forced by seeding. This property has been used to separate racemic mixtures.

Further commercial uses

• A stabilizer in nitrocellulose explosives
• A reactant in the NO_x-reducing SNCR and SCR reactions in exhaust gases from combustion, for example, from power plants and diesel engines
• A component of fertilizer and animal feed, providing a relatively cheap source of nitrogen to promote growth
• A raw material for the manufacture of plastics, to be specific, urea-formaldehyde resin
• A raw material for the manufacture of various glues (urea-formaldehyde or urea-melamine-formaldehyde); the latter is waterproof and is used for marine plywood
• An alternative to rock salt in the deicing of roadways and runways; it does not promote metal corrosion to the extent that salt does
• An additive ingredient in cigarettes, designed to enhance flavour
• A browning agent in factory-produced pretzels
• An ingredient in some hair conditioners, facial cleansers, bath oils, and lotions
• A reactant in some ready-to-use cold compresses for first-aid use, due to the endothermic reaction it creates when mixed with water
• A cloud seeding agent, along with salts, to expedite the condensation of water in clouds, producing precipitation
• An ingredient used in the past to separate paraffins, due to the ability of urea to form clathrates (also called host-guest complexes, inclusion compounds, and adducts)
• A flame-proofing agent (commonly used in dry chemical fire extinguishers as Urea-potassium bicarbonate)
• An ingredient in many tooth whitening products
• A cream to soften the skin, especially cracked skin on the bottom of one's feet
• An ingredient in dish soap.
• To make potassium cyanate
• A melt agent used in re-surfacing snowboarding halfpipes and terrain park features

// The term nitrogen oxide typically refers to any binary compound of oxygen and nitrogen, or to a mixture of such compounds: Nitric oxide (NO), nitrogen(II) oxide Nitrogen dioxide (NO2), nitrogen(IV) oxide Nitrous oxide (N2O), nitrogen (I) oxide Dinitrogen trioxide (N2O3), nitrogen(II, IV) oxide Dinitrogen tetroxide (N2O4), nitrogen... Selective Non Catalytic Reduction (SNCR) is a method for reducing nitrogen oxide emissions in conventional power plants that burn biomass. ... Selective Catalytic Reduction (SCR): Gaseous or liquid ammonia is added to the flue gas stream and is absorbed onto a catalyst. ... Automobile exhaust Exhaust gas is flue gas which occurs as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel, fuel oil or coal. ... This article is about the chemical reaction combustion. ... A power station (also power plant) is a facility for the generation of electric power. ... Diesel engines in a museum Diesel generator on an oil tanker A diesel engine is an internal combustion engine which operates using the Diesel cycle. ... Spreading manure, an organic fertilizer Fertilizers (also spelled fertilisers) are compounds given to plants to promote growth; they are usually applied either through the soil, for uptake by plant roots, or by foliar feeding, for uptake through leaves. ... In agriculture, fodder or animal feed is any foodstuff that is used specifically to feed livestock, such as cattle, sheep, chickens and pigs. ... For other uses, see Plastic (disambiguation). ... A urea-formaldehyde resin is a transparent thermosetting resin made from urea and formaldehyde heated in the presence of such a mild base as ammonia or pyridine. ... Unlit filtered cigarettes. ... This article is about flavor, the sensory impression. ... A pretzel is a baked snack that is ordinarily twisted into a unique knot-like shape. ... A reactant or reagent is any substance initially present in a chemical reaction. ... This article is about the physical effect. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Cessna 210 with cloud seeding equipment Cloud seeding, a form of weather modification, is the attempt to change the amount or type of precipitation that falls from clouds, by dispersing substances into the air that serve as cloud condensation or ice nuclei. ... A clathrate or clathrate compound is a chemical substance consisting of a Greek klethra, meaning bars (in the sense of a lattice). ... Tooth bleaching, also known as tooth whitening, is a common procedure in general dentistry but most especially in the field of cosmetic dentistry. ... Potassium cyanate or potassium isocyanate is an inorganic compound and the potassium salt of cyanic acid with the chemical formula of KOCN (also: KCNO). ...

Laboratory use

Urea is a powerful protein denaturant. This property can be exploited to increase the solubility of some proteins. For this application, it is used in concentrations up to 10 M. Urea is used to effectively disrupt the noncovalent bonds in proteins. Urea is an ingredient in the synthesis of urea nitrate. Urea nitrate is also a high explosive very similar to ammonium nitrate, however it may even be more powerful because of its complexity. VOD is 11,000 fps to 15,420 fps. A representation of the 3D structure of myoglobin showing coloured alpha helices. ... Irreversible egg protein denaturation and loss of solubility, caused by the high temperature (while cooking it) Denaturation is the alteration of a protein or nucleic acids shape through some form of external stress (for example, by applying heat, acid or alkali), in such a way that it will no... In chemistry, the molar volume of a substance is the ratio of the volume of a sample of that substance to the amount of substance (usually in mole) in the sample. ...

Medical use

Drug use

Urea is used in topical dermatological products to promote rehydration of the skin. If covered by an occlusive dressing, 40% urea preparations may also be used for nonsurgical debridement of nails. This drug is also used as an earwax removal aid. Dermatology (from Greek δερμα, skin) is a branch of medicine dealing with the skin and its appendages (hair, sweat glands, etc). ... Rehydration is the pissing of water and electrolytes lost through dehydration. ... This article is about the organ. ... An occlusive dressing is an air- and water-tight trauma dressing used in first aid. ... Debridement is a medical term referring to the removal of dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue. ... For other uses, see Nail. ...

Clinical diagnosis

Main article: blood urea nitrogen

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. The blood urea nitrogen (BUN) test is a measure of the amount of nitrogen in the blood that comes from urea. ... In medicine (nephrology) renal function is an indication of the state of the kidney and its role in physiology. ...

Other diagnostic use

Isotopically-labeled urea (carbon-14 - radioactive, or carbon-13 - stable isotope) is used in the urea breath test, which is used to detect the presence of the bacteria Helicobacter pylori (H. pylori) in the stomach and duodenum of humans. The test detects the characteristic enzyme urease, produced by H. pylori, by a reaction that produces ammonia from urea. This increases the pH (reduces 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).^[vague] Carbon-14 is the radioactive isotope of carbon discovered February 27, 1940, by Martin Kamen and Sam Ruben. ... Carbon-13 is a stable isotope of carbon. ... The urea breath test is a rapid diagnostic procedure used to identify infections by Helicobacter pylori, a spiral bacterium implicated in gastritis, gastric ulcer, and peptic ulcer disease. ... Binomial name ((Marshall 1985) Goodwin 1989) ICD-9 code: 041. ... Helicobacter Pylori Urease drawn from PDB 1E9Z. Urease (EC 3. ... This article is about large cat species. ...

Textile use

Urea in textile laboratories are frequently used both in dyeing and printing as an important auxiliary, which provides solubility to the bath and retains some moisture required for the dyeing or printing process.

Ionic liquid

Choline chloride, in mixture with urea, is used as a deep eutectic solvent, a type of ionic liquid. Choline chloride or N-(2-Hydroxyethyl)trimethylammonium chloride is an organic compound and a quaternary ammonium salt. ... A deep eutectic solvent or DES is a type of ionic solvent with special properties composed of a mixture which forms a eutectic with a melting point much lower than either of the individual components. ... Ionic liquid An ionic liquid is a liquid that contains essentially only ions. ...

Ureas

The term urea or carbamide is also used for the class of chemical compounds sharing the same functional group RR'N-CO-NRR' based on a carbonyl group flanked by two organic amine residues. They can be accessed in the laboratory by reaction of phosgene with primary or secondary amines. Example of ureas are the compounds carbamide peroxide, allantoin, and Hydantoin. Ureas are closely related to biurets and related in structure to amides, carbamates, diimides, carbodiimides, and thiocarbamides. Look up chemical compound in Wiktionary, the free dictionary. ... In organic chemistry, functional groups (or moieties) are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules. ... Carbonyl group In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom : C=O. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e. ... The general structure of an amine Amines are organic compounds and a type of functional group that contain nitrogen as the key atom. ... Phosgene is a highly toxic chemical compound with the formula COCl2. ... The general structure of an amine Amines are organic compounds and a type of functional group that contain nitrogen as the key atom. ... Carbamide peroxide is an oxidising agent, consisting of hydrogen peroxide compounded with urea. ... Allantoin is a botanical extract of the comfrey plant and is used for its healing, soothing, and anti-irritating properties. ... Hydantoin, which is also known as glycolylurea, is a heterocyclic organic compound which can be thought of as a cyclic double-condensation reaction product of glycolic acid and urea. ... Biuret is a chemical compound with the chemical formula C2O2N3H5. ... Amide functional group Amides possess a conjugated system spread over the O, C and N atoms, consisting of molecular orbitals occupied by delocalized electrons. ... Carbamates are a group of organic compounds sharing a common functional group with the general structure -NH(CO)O-. More precisely the carbamate group is considered an amide group with an alkoxy or hydroxy functional group next to the carbonyl group. ... In chemistry, azo compounds generally have a molecular formula of the form R-N=N-R, in which R and R can be either aromatic or aliphatic. ... A carbodiimide is a functional group consisting of the formula N=C=N. Carbodiimides hydrolyze to form ureas, which makes them rarely found in nature. ... Thiourea is an organic compound of carbon, nitrogen, sulfur and hydrogen, with the formula CSN2H4 or (NH2)2CS. It is similar to urea, except that the oxygen atom is replaced by a sulfur atom. ...

Reactions

Urea reacts with alcohols to form urethanes. Urea reacts with malonic esters to make barbituric acids. Urethane (also called ethyl carbamate) 1. ... Malonic acid (IUPAC systematic name: propanedioic acid) is a dicarboxylic acid with structure CH2(COOH)2. ... Barbituric acid or malonylurea or 4-hydroxyuracyl is an organic compound based on a pyrimidine heterocyclic skeleton. ...

References

External links

• MSDS sheet on urea
• Use of urea in hand dyeing