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Urea, also known as carbamide, is an
organic compound In , organic compounds are generally any s that contain - . Due to carbon's ability to (form chains with other carbon s), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds compr ...
with
chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and ...
CO(NH2)2. This
amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a chemical compound, compound with the general formula RC(=O)NR′R″, where R, R', and R″ represent organic compound, organic functional group, groups or ...

amide
has two –NH2 groups joined by a
carbonyl In organic chemistry Organic chemistry is a branch of chemistry that studies the structure, properties and reactions of organic compounds, which contain carbon in covalent bonding.Clayden, J.; Greeves, N. and Warren, S. (2012) ''Organic Chemistr ...

carbonyl
(C=O)
functional group In organic chemistry, a functional group is a substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions re ...
. Urea serves an important role in the
metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life Life is a characteristic that distinguishes physical entities that have biological processes, such as Cell signaling, signaling and self-sustaining ...

metabolism
of
nitrogen Nitrogen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

nitrogen
-containing compounds by animals and is the main nitrogen-containing substance in the
urine Urine is a liquid by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and ...

urine
of
mammal Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republ ...
s. It is a colorless, odorless solid, highly soluble in water, and practically non-toxic ( is 15 g/kg for rats). Dissolved in water, it is neither
acid An acid is a or capable of donating a (hydrogen ion H+) (a ), or, alternatively, capable of forming a with an (a ). The first category of acids are the proton donors, or s. In the special case of , proton donors form the H3O+ and are ...
ic nor
alkaline In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds composed of ato ...
. The body uses it in many processes, most notably nitrogen excretion. The
liver The liver is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's t ...

liver
forms it by combining two
ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...

ammonia
molecules (NH3) with a
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is ...

carbon dioxide
(CO2) molecule in the
urea cycle The urea cycle (also known as the ornithine cycle) is a cycle of biochemical Biochemistry or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, bioch ...

urea cycle
. Urea is widely used in
fertilizer A fertilizer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American E ...

fertilizer
s as a source of nitrogen (N) and is an important
raw material A raw material, also known as a feedstock, unprocessed material, or primary commodity, is a basic material that is used to produce goods, finished Product (business), products, energy, or intermediate materials that are feedstock for future finis ...
for the
chemical industry The chemical industry comprises the companies A company, abbreviated as co., is a Legal personality, legal entity representing an association of people, whether Natural person, natural, Legal personality, legal or a mixture of both, with a spe ...
.
Friedrich Wöhler Friedrich Wöhler () FRS(For) HFRSE Fellowship of the Royal Society of Edinburgh (FRSE) is an award granted to individuals that the Royal Society of Edinburgh, Scotland's national academy of science and Literature, letters, judged to be "em ...

Friedrich Wöhler
discovered that urea can be produced from inorganic starting materials, which was an important conceptual milestone in chemistry in 1828. It 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 Vitalism is the belief that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things". Where vitalism explicitly invoke ...
, which stated that only living things could produce the chemicals of life.


Uses


Agriculture

More than 90% of world industrial production of urea is destined for use as a nitrogen-release
fertilizer A fertilizer (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American E ...

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 A nutrient is a substance Substance may refer to: * Substance (Jainism), a term in Jain ontology to denote the base or owner of attributes * Chemical substance, a material with a definite chemical composition * Matter, anything that has mass and t ...
. The most common impurity of synthetic urea is
biuret Biuret is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. Al ...

biuret
, which impairs plant growth. Urea breaks down in the soil to give ammonium. The ammonium is taken up by the plant. In some soils, the ammonium is oxidized by bacteria to give nitrate, which is also a plant nutrient. The loss of nitrogenous compounds to the atmosphere and runoff is both wasteful and environmentally damaging. For this reason, urea is sometimes pretreated or modified to enhance the efficiency of its agricultural use. One such technology is
controlled-release fertilizerimage:Methylene diurea.svg, 224px, Methylene diurea (MDU) is component of the most popular controlled-release fertilizers. A controlled-release fertiliser (CRF) is a granulated fertiliser that releases nutrients gradually into the soil (i.e., with a ...
s, which contain urea encapsulated in an inert sealant. Another technology is the conversion of urea into derivatives, such as with formaldehyde, which degrade into ammonia at a pace matching plants' nutritional requirements.


Resins

Urea is a raw material for the manufacture of two main classes of materials: urea-formaldehyde resins and urea-melamine-formaldehyde used in marine
plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer In woodworking, veneer refers to thin slices of wood and sometimes bark, usually thinner than 3 mm (1/8 inch), that typically are glued onto core panels (typic ...

plywood
.


Explosives

Urea can be used to make
urea nitrate Urea nitrate is a fertilizer-based high explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion An explosion is a rapid expansion in volume as ...

urea nitrate
, a
high explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion An explosion is a rapid expansion in volume Volume is a expressing the of enclosed by a . ...
that is used industrially and as part of some
improvised explosive devices An improvised explosive device (IED) is a bomb constructed and deployed in ways other than in conventional warfare, conventional military action. It may be constructed of conventional military explosives, such as an artillery shell, attached to a ...
.


Automobile systems

Urea is used in Selective Non-Catalytic Reduction (SNCR) and Selective Catalytic Reduction (SCR) reactions to reduce the NOx
pollutant A pollutant is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. A pollutant may cause long- or short-term damage by changing the growth rate of plant or animal s ...
s in
exhaust gas Exhaust gas or flue gas Flue gas is the gas exiting to the atmosphere via a flue, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler Poland Poland ( pl, Polska ), officially the Republic ...
es from
combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combustion ...
from
diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engine ...
, dual fuel, and lean-burn
natural gas Natural gas (also called fossil gas; sometimes just gas) is a naturally occurring hydrocarbon gas mixture consisting of methane and commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxid ...

natural gas
engines. The
BlueTecBlueTEC is Daimler AG Daimler AG (; previously named Daimler-Benz and DaimlerChrysler; commonly known and referred to as Mercedes-Benz, or simply as Daimler) is a German multinational automotive corporation headquartered in Stuttgart of t ...
system, for example, injects a water-based urea solution into the exhaust system. The ammonia produced by the
hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution Substitution may refer to: Arts and media *Chord substitution, in music, swapping one chord fo ...

hydrolysis
of the urea reacts with the nitrogen oxide emissions and is converted into nitrogen and water within the catalytic converter. Trucks and cars using these catalytic converters need to carry a supply of diesel exhaust fluid, a solution of urea in water.


Laboratory uses

Urea in concentrations up to 10
M
M
is a powerful
protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...

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 Choline chloride is an organic compound with the formula (CH3)3NCH2CH2OH]Cl. It is bifunctional, containing both quaternary ammonium salt and an alcohol. The cation is choline, which occurs naturally. It is a white, water-soluble salt (chemistry), ...

choline chloride
is used as a
deep eutectic solventDeep eutectic solvents are systems formed from a eutectic mixture of Lewis or Brønsted acids and bases which can contain a variety of anionic and/or cationic species. They are classified as types of ionic solvents with special properties. They in ...
(DES), a substance similar to
ionic liquid An ionic liquid (IL) is a salt Salt is a mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure ...
. When used in a deep eutectic solvent, urea does not denature the proteins that are solubilized. Urea can in principle serve as a hydrogen source for subsequent power generation in
fuel cell A fuel cell is an electrochemical cell An electrochemical cell is a device capable of either generating electrical energy Electrical energy is energy derived from electric potential energy or kinetic energy. When used loosely, ''electri ...

fuel cell
s. 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 Dermatology is the branch of medicine dealing with the skin.''Random House Webster's Unabridged Dictionary.'' Random House, Inc. 2001. Page 537. . It is a speciality with both medical and surgical aspects. A List of dermatologists, dermatologist ...
products to promote rehydration of the
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have differ ...

skin
. Urea 40% is indicated for
psoriasis Psoriasis is a long-lasting, noncontagious autoimmune disease An autoimmune disease is a condition arising from an abnormal immune response to a functioning body part. There are at least 80 types of autoimmune diseases. Nearly any body part c ...

psoriasis
, xerosis,
onychomycosis Onychomycosis, also known as tinea unguium, is a fungal infection of the nail Nail or Nails may refer to: In biology * Nail (anatomy), toughened protective protein-keratin (known as alpha-keratin, also found in hair) at the end of an animal di ...

onychomycosis
,
ichthyosis Ichthyosis is a family of genetic skin disorders characterized by dry, thickened, scaly skin. The more than 20 types of ichthyosis range in severity of symptoms, outward appearance, underlying genetic cause and mode of inheritance (e.g., dominant ...
,
eczema Dermatitis is of the , typically characterized by iness, and a . In cases of short duration, there may be small s, while in long-term cases the skin may become . The area of skin involved can vary from small to covering the entire body. Derma ...

eczema
,
keratosis Keratosis (from '' kerat-'' + '' -osis'') is a growth of keratin Keratin () is one of a family of fibrous structural proteins known as Scleroprotein, scleroproteins. ''Alpha-keratin, α-Keratin'' is a type of keratin found in vertebrates. It is t ...
,
keratoderma Keratoderma is a hornlike skin condition. Classification The keratodermas are classified into the following subgroups:Freedberg, et al. (2003). ''Fitzpatrick's Dermatology in General Medicine''. (6th ed.). McGraw-Hill. . Congenital * Simple kera ...
, corns, and
calluses A callus is an area of thickened skin that forms as a response to repeated friction, pressure, or other irritation. Since repeated contact is required, calluses are most often found on the feet and hands, but they may occur anywhere on the sk ...

calluses
. If covered by an
occlusive dressing An occlusive dressing is an air- and water-tight trauma medical dressing used in first aid First aid is the first and immediate assistance given to any person suffering from either a minor or serious illness A disease is a particul ...
, 40% urea preparations may also be used for nonsurgical
debridement Debridement is the medical removal of dead, damaged, or infected tissue (biology), tissue to improve the healing potential of the remaining healthy tissue. Removal may be surgery, surgical, mechanical, chemical, Autolysis (biology), autolytic ...
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 Hydrogen peroxide - urea (also called Hyperol, artizone, urea hydrogen peroxide, and UHP) is a solid composed of equal amounts of hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale b ...

carbamide peroxide
) is also used as an earwax removal aid. Urea has also been studied as a
diuretic A diuretic () is any substance that promotes diuresis Diuresis () is increased urination Urination is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretio ...
. It was first used by Dr. W. Friedrich in 1892. In a 2010 study of ICU patients, urea was used to treat euvolemic
hyponatremia Hyponatremia is a low sodium concentration in the Serum (blood), blood. It is generally defined as a sodium concentration of less than 135 mmol/L (135 mEq/L), with severe hyponatremia being below 120 mEq/L. Symptoms can be absent, mild or severe. ...
and was found safe, inexpensive, and simple. Like saline, urea injection has previously been used to perform
abortion Abortion is the ending of a pregnancy Pregnancy, also known as gestation, is the time during which one or more offspring In biology, offspring are the young born of living organism, organisms, produced either by a single organism ...

abortion
. The
blood urea nitrogen Blood urea nitrogen (BUN) is a medical test that measures the amount of urea nitrogen found in blood. The liver produces urea Urea, also known as carbamide, is an organic compound In , organic compounds are generally any s that contain - ...
(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 Assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging. Functions of a healthy kidney include maintaining a person's fluid ...
, though it is inferior to other markers such as
creatinine Creatinine ( or ; from el, κρέας, kreas, flesh) is a breakdown product of creatine phosphate Phosphocreatine, also known as creatine phosphate (CP) or PCr (Pcr), is a phosphorylated creatine molecule that serves as a rapidly mobilizable ...

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 An excipient is a substance formulated alongside the active ingredient of a medication, included for the purpose of long-term stabilization, bulking up solid formulations that contain potent active ingredients in small amounts (thus often referred ...
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 Endothelium is a single layer of squamous Epithelium () is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With ...
. Urea labeled with
carbon-14 Carbon-14 (14C), or radiocarbon, is a radioactive isotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ...

carbon-14
or
carbon-13 Carbon-13 (13C) is a natural, stable isotope The term stable isotope has a meaning similar to stable nuclide Stable nuclides are nuclide A nuclide (or nucleide, from nucleus, also known as nuclear species) is a class of atoms characterized by ...

carbon-13
is used in the
urea breath test The urea breath test is a rapid medical diagnosis, diagnostic procedure used to identify infections by ''Helicobacter pylori'', a spiral bacterium implicated in gastritis, gastric ulcer, and peptic ulcer disease. It is based upon the ability of ''H ...
, which is used to detect the presence of the bacterium ''
Helicobacter pylori ''Helicobacter pylori'', previously known as ''Campylobacter pylori'', is a gram-negative, microaerophile, microaerophilic, spiral bacteria, spiral (helical) bacterium usually found in the stomach. Its helical shape (from which the genus name, ...

Helicobacter pylori
'' (''H. pylori'') in the
stomach The stomach is a muscular, in the of humans and many other animals, including several s. The stomach has a dilated structure and functions as a vital organ. In the digestive system the stomach is involved in the second phase of digestion, ...

stomach
and
duodenum The duodenum is the first section of the small intestine The small intestine or small bowel is an organ (anatomy), organ in the human gastrointestinal tract, gastrointestinal tract where most of the #Absorption, absorption of nutrients from foo ...

duodenum
of humans, associated with
peptic ulcer Peptic ulcer disease (PUD) is a break in the inner Gastric mucosa, lining of the stomach, the first part of the small intestine, or sometimes the lower esophagus. An ulcer in the stomach is called a gastric ulcer, while one in the first part of t ...

peptic ulcer
s. The test detects the characteristic enzyme
urease Ureases (), functionally, belong to the superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially i ...

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
ape Apes (Hominoidea ) are a branch The branches and leaves of a tree. A branch ( or , ) or tree branch (sometimes referred to in botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of bi ...

ape
s,
dog The dog or domestic dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a Domestication, domesticated descendant of the wolf which is characterized by an upturning tail. The dog Origin of the domestic dog, derived from an Pleistocene ...

dog
s, and
cat The cat (''Felis catus'') is a domestic Domestic may refer to: In the home * Anything relating to the human home A home, or domicile, is a space used as a permanent or semi-permanent residence for an individual, group or family ...

cat
s (including
big cat The term "big cat" is typically used to refer to any of the five living members of the genus '' Panthera'', namely the lion, tiger, jaguar, leopard, and snow leopard, as well as the non- pantherine cheetah and cougar. Except for the latter thr ...

big cat
s).


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 In atmospheric chemistry Atmospheric chemistry is a branch of in which the of the and that of other planets is studied. It is a of research and draws on , , , , , and and other disciplines. Research is increasingly connected with other a ...

NOx
emissions into harmless
nitrogen Nitrogen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

nitrogen
and
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...

water
. *A component of
animal feed Animal feed is food Food is any substance consumed to provide nutritional support for an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that emb ...
, providing a relatively cheap source of
nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...
to promote growth * A non-corroding alternative to
rock salt Halite ( or ), commonly known as rock salt, is a type of salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its natural form as a cry ...

rock salt
for road
de-icing De-icing is the process of removing snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It cons ...
. 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 removers such as
Nair The Nair , also known as Nayar, are a group of Indian Hindu castes, described by anthropologist Kathleen Gough as "not a unitary group but a named category of castes". The Nair include several castes and many subdivisions, not all of whom histori ...
and
Veet Veet, formerly called Neet and Immac, is a Canadian Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these ...
* A browning agent in factory-produced
pretzel A pretzel (), from dialectal German pronunciation, standard german: Breze(l) ( and French / Alsatian: ''Bretzel'') is a type of baked Baking is a method of preparing food that uses dry heat, typically in an oven, but can also be done in ho ...

pretzel
s * An ingredient in some skin cream,
moisturizer White petrolatum Moisturizer, or emollient, is a cosmetic preparation used for protecting, moisturizing, and lubricating the skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main ...
s,
hair conditioner Hair conditioner is a hair care product used to improve the feel, appearance and manageability of hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The ...
s, and
shampoo Shampoo () is a hair care Hair care is an overall term for hygiene Hygiene is a series of practices performed to preserve health Health, according to the World Health Organization, is "a state of complete physical, Mental health, men ...

shampoo
s * A
cloud seeding Cloud seeding is a type of weather modification Weather modification (also known as weather control) is the act of intentionally manipulating or altering the weather Weather is the state of the atmosphere, describing for example the de ...
agent, along with other salts * A flame-proofing agent, commonly used in dry chemical
fire extinguisher A fire extinguisher is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user ...

fire extinguisher
charges such as the urea-
potassium bicarbonate Potassium bicarbonate (also known as potassium hydrogen carbonate or potassium acid carbonate) is the inorganic compound In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, comp ...

potassium bicarbonate
mixture * An ingredient in many
tooth whitening Tooth whitening or tooth bleaching is the process of lightening the color of human teeth. Whitening is often desirable when teeth become yellowed over time for a number of reasons, and can be achieved by changing the intrinsic or extrinsic color o ...
products * An ingredient in
dish soap Dishwashing liquid ( BrE: washing-up liquid), known as dishwashing soap, dish detergent and dish soap, is a detergent used to assist in dishwashing. It is usually a highly-foam foam bubbles Foam is an object formed by trapping pockets o ...
* Along with
diammonium phosphate Diammonium phosphate (DAP; IUPAC name diammonium hydrogen phosphate; chemical formula (NH4)2(HPO4) is one of a series of water-soluble ammonium phosphate salt (chemistry), salts that can be produced when ammonia reacts with phosphoric acid. Solid ...

diammonium phosphate
, as a yeast nutrient, for fermentation of sugars into ethanol * A nutrient used by plankton in ocean nourishment experiments for climate engineering, geoengineering purposes * As an additive to extend the working temperature and open time of hide glue * As a solubility-enhancing and moisture-retaining additive to dye baths for textile dyeing or printing * As an optical parametric oscillator in nonlinear optics


Adverse effects

Urea can be irritating to skin, eyes, and the respiratory tract. Repeated or prolonged contact with urea in fertilizer form on the skin may cause dermatitis. High concentrations in the blood can be damaging. Ingestion of low concentrations of urea, such as are found in typical human
urine Urine is a liquid by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and ...

urine
, are not dangerous with additional water ingestion within a reasonable time-frame. Many animals (e.g., dogs) have a much more concentrated urine and it contains a higher urea amount than normal human urine; this can prove dangerous as a source of liquids for consumption in a life-threatening situation (such as in a desert). Urea can cause algal blooms to produce toxins, and its presence in the runoff from fertilized land may play a role in the increase of toxic blooms. 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.


Physiology

Amino acids from ingested food that are used for the synthesis of proteins and other biological substances — or produced from catabolism of muscle protein — are oxidized by the body as an alternative source of energy, yielding urea and
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is ...

carbon dioxide
. The oxidation pathway starts with the removal of the amino group by a transaminase; the amino group is then fed into the
urea cycle The urea cycle (also known as the ornithine cycle) is a cycle of biochemical Biochemistry or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, bioch ...

urea cycle
. The first step in the conversion of amino acids from protein into Metabolic waste#Nitrogen wastes, metabolic waste in the liver is removal of the alpha-amino nitrogen, which results in
ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...

ammonia
. Because ammonia is toxic, it is excreted immediately by fish, converted into uric acid by birds, and converted into urea by mammals. Ammonia (NH3) is a common byproduct of the metabolism of nitrogenous compounds. Ammonia is smaller, more volatile and more mobile than urea. If allowed to accumulate, ammonia would raise the pH in cells to toxic levels. Therefore, many organisms convert ammonia to urea, even though this synthesis has a net energy cost. Being practically neutral and highly soluble in water, urea is a safe vehicle for the body to transport and excrete excess nitrogen. Urea is synthesized in the body of many organisms as part of the
urea cycle The urea cycle (also known as the ornithine cycle) is a cycle of biochemical Biochemistry or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, bioch ...

urea cycle
, either from the oxidation of amino acids or from
ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...

ammonia
. 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. Urea production occurs in the
liver The liver is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given organ's t ...

liver
and is regulated by N-acetylglutamate. Urea is then dissolved into the blood (in the reference ranges for blood tests, reference range of 2.5 to 6.7 mmol/liter) and further transported and excreted by the kidney as a component of
urine Urine is a liquid by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and ...

urine
. In addition, a small amount of urea is excreted (along with sodium chloride and water) in sweat. In water, the amine groups undergo slow displacement by water molecules, producing ammonia, ammonium ion, and bicarbonate ion. For this reason, old, stale urine has a stronger odor than fresh urine.


Humans

The renal urea handling, cycling of and excretion of urea by the kidneys is a vital part of mammalian metabolism. Besides its role as carrier of waste nitrogen, urea also plays a role in the countercurrent exchange system of the nephrons, that allows for re-absorption of water and critical ions from the excreted
urine Urine is a liquid by-product A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and ...

urine
. Urea is reabsorbed in the inner medullary collecting ducts of the nephrons, Page 837 thus raising the osmolarity in the renal interstitium, medullary interstitium surrounding the thin descending limb of the loop of Henle, which makes the water reabsorb. By action of the urea transporter 2, some of this reabsorbed urea eventually flows back into the thin descending limb of the tubule, through the collecting ducts, and into the excreted urine. The body uses this mechanism, which is controlled by the antidiuretic hormone, to create hyperosmotic urine—i.e., urine with a higher concentration of dissolved substances than the blood plasma. This mechanism is important to prevent the loss of water, maintain blood pressure, and maintain a suitable concentration of sodium ions in the blood plasma. The equivalent nitrogen content (in gram) of urea (in Mole (unit), mmol) can be estimated by the conversion factor 0.028 g/mmol. Furthermore, 1 gram of nitrogen is roughly equivalent to 6.25 grams of
protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a No ...

protein
, and 1 gram of protein is roughly equivalent to 5 grams of muscle tissue. In situations such as muscle wasting, 1 mmol of excessive urea in the urine (as measured by urine volume in litres multiplied by urea concentration in mmol/l) roughly corresponds to a muscle loss of 0.67 gram.


Other species

In marine biology, aquatic organisms the most common form of nitrogen waste is ammonia, whereas land-dwelling organisms convert the toxic ammonia to either urea or uric acid. Urea is found in the urine of
mammal Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republ ...
s and amphibians, as well as some fish. Birds and saurian reptiles have a different form of nitrogen metabolism that requires less water, and leads to nitrogen excretion in the form of uric acid. Tadpoles excrete ammonia but shift to urea production during metamorphosis (biology), metamorphosis. Despite the generalization above, the urea 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.


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: RR'N—CO—NRR'. Examples include
carbamide peroxide Hydrogen peroxide - urea (also called Hyperol, artizone, urea hydrogen peroxide, and UHP) is a solid composed of equal amounts of hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale b ...

carbamide peroxide
, allantoin, and hydantoin. Ureas are closely related to
biuret Biuret is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. Al ...

biuret
s and related in structure to
amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a chemical compound, compound with the general formula RC(=O)NR′R″, where R, R', and R″ represent organic compound, organic functional group, groups or ...

amide
s, carbamates, carbodiimides, and thiocarbamides.


History

Urea was first discovered in urine in 1727 by the Dutch scientist Herman Boerhaave, although this discovery is often attributed to the France, French chemist Hilaire Rouelle as well as William Cruickshank (chemist), William Cruickshank. Boerhaave used the following steps to isolate urea: # Boiled off water, resulting in a substance similar to fresh cream # Used filter paper to squeeze out remaining liquid # Waited a year for solid to form under an oily liquid # Removed the oily liquid # Dissolved the solid in water # Used Recrystallization (chemistry), recrystallization to tease out the urea In 1828, the Germany, German chemist
Friedrich Wöhler Friedrich Wöhler () FRS(For) HFRSE Fellowship of the Royal Society of Edinburgh (FRSE) is an award granted to individuals that the Royal Society of Edinburgh, Scotland's national academy of science and Literature, letters, judged to be "em ...

Friedrich Wöhler
obtained urea artificially by treating silver cyanate with ammonium chloride. : AgNCO + NH4Cl → (NH2)2CO + AgCl This was the first time an organic compound was artificially synthesized from inorganic starting materials, without the involvement of living organisms. The results of this experiment implicitly discredited
vitalism Vitalism is the belief that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things". Where vitalism explicitly invoke ...
 — the theory that the chemicals of living organisms are fundamentally different from those of inanimate matter. This insight was important for the development of organic chemistry. His discovery prompted Wöhler to write triumphantly to Jöns Jakob Berzelius, Berzelius: "I must tell you that I can make urea without the use of kidneys, either man or dog. Ammonium cyanate is urea." In fact, this was incorrect. These are two different chemicals with the same overall
chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and ...
N2H4CO, which are in chemical equilibrium heavily favoring urea under standard conditions. Regardless, with his discovery, Wöhler secured a place among the pioneers of organic chemistry.


Production

Urea is produced on an industrial scale: In 2012, worldwide production capacity was approximately 184 million tonnes.


Industrial methods

For use in industry, urea is produced from synthetic
ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...

ammonia
and
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is ...

carbon dioxide
. As large quantities of carbon dioxide are produced during the ammonia manufacturing process as a byproduct from hydrocarbons (predominantly natural gas, less often petroleum derivatives), or occasionally from coal (steam shift reaction), urea production plants are almost always located adjacent to the site where the ammonia is manufactured. Although natural gas is both the most economical and the most widely available ammonia plant feedstock, plants using it do not produce quite as much carbon dioxide from the process as is needed to convert their entire ammonia output into urea. In recent years new technologies such as the KM-CDR process have been developed to recover supplementary carbon dioxide from the combustion exhaust gases produced in the fired reforming furnace of the ammonia synthesis gas plant, allowing operators of stand-alone nitrogen fertilizer complexes to avoid the need to handle and market ammonia as a separate product and also to reduce their greenhouse gas emissions to the atmosphere.


Synthesis

The basic process, developed in 1922, is also called the Bosch–Meiser urea process after its discoverers. Various commercial urea processes are characterized by the conditions under which urea forms and the way that unconverted reactants are further processed. The process consists of two main equilibrium reactions, with incomplete conversion of the reactants. The first is carbamate formation: the fast exothermic reaction of liquid ammonia with gaseous carbon dioxide (CO2) at high temperature and pressure to form ammonium carbamate (H2N-COONH4): :2 NH3 + CO2 H2N-COONH4 (ΔH= -117kJ/mol at 110 atm and 160°C) The second is urea conversion: the slower endothermic decomposition of ammonium carbamate into urea and water: :H2N-COONH4 (NH2)2CO + H2O (ΔH= +15.5 kJ/mol at 160-180°C) The overall conversion of NH3 and CO2 to urea is exothermic, the reaction heat from the first reaction driving the second. Like all chemical equilibria, these reactions behave according to Le Chatelier's principle, and the conditions that most favour carbamate formation have an unfavourable effect on the urea conversion equilibrium. The process conditions are, therefore, a compromise: the ill-effect on the first reaction of the high temperature (around 190 °C) needed for the second is compensated for by conducting the process under high pressure (140–175 bar), which favours the first reaction. Although it is necessary to compress gaseous carbon dioxide to this pressure, the ammonia is available from the ammonia plant in liquid form, which can be pumped into the system much more economically. To allow the slow urea formation reaction time to reach equilibrium a large reaction space is needed, so the synthesis reactor in a large urea plant tends to be a massive pressure vessel. Because the urea conversion is incomplete, the product must be separated from unchanged ammonium carbamate. In early "straight-through" urea plants this was done by letting down the system pressure to atmospheric to let the carbamate decompose back to ammonia and carbon dioxide. Originally, because it was not economic to recompress the ammonia and carbon dioxide for recycle, the ammonia at least would be used for the manufacture of other products, for example ammonium nitrate or sulfate. (The carbon dioxide was usually wasted.) Later process schemes made recycling unused ammonia and carbon dioxide practical. This was accomplished by depressurizing the reaction solution in stages (first to 18–25 bar and then to 2–5 bar) and passing it at each stage through a steam-heated ''carbamate decomposer'', then recombining the resultant carbon dioxide and ammonia in a falling-film ''carbamate condenser'' and pumping the carbamate solution into the previous stage.


= Stripping concept

= The "total recycle" concept has two main disadvantages. The first is the complexity of the flow scheme and, consequently, the amount of process equipment needed. The second is the amount of water recycled in the carbamate solution, which has an adverse effect on the equilibrium in the urea conversion reaction and thus on overall plant efficiency. The stripping concept, developed in the early 1960s by Stamicarbon in The Netherlands, addressed both problems. It also improved heat recovery and reuse in the process. The position of the equilibrium in the carbamate formation/decomposition depends on the product of the partial pressures of the reactants. In the total recycle processes, carbamate decomposition is promoted by reducing the overall pressure, which reduces the partial pressure of both ammonia and carbon dioxide. It is possible, however, to achieve a similar effect without lowering the overall pressure—by suppressing the partial pressure of just one of the reactants. Instead of feeding carbon dioxide gas directly to the reactor with the ammonia, as in the total recycle process, the stripping process first routes the carbon dioxide through a stripper (a carbamate decomposer that operates under full system pressure and is configured to provide maximum gas-liquid contact). This flushes out free ammonia, reducing its partial pressure over the liquid surface and carrying it directly to a carbamate condenser (also under full system pressure). From there, reconstituted ammonium carbamate liquor passes directly to the reactor. That eliminates the medium-pressure stage of the total recycle process altogether. The stripping concept was such a major advance that competitors such as Snamprogetti—now Saipem—(Italy), the former Montedison (Italy), Toyo Engineering Corporation (Japan), and Urea Casale (Switzerland) all developed versions of it. Today, effectively all new urea plants use the principle, and many total recycle urea plants have converted to a stripping process. No one has proposed a radical alternative to the approach. The main thrust of technological development today, in response to industry demands for ever larger individual plants, is directed at re-configuring and re-orientating major items in the plant to reduce size and overall height of the plant, and at meeting challenging environmental performance targets.


= Side reactions

= It is fortunate that the urea conversion reaction is slow. If it were not it would go into reverse in the stripper. As it is, succeeding stages of the process must be designed to minimize residence times, at least until the temperature reduces to the point where the reversion reaction is very slow. Two reactions produce impurities. Biuret is formed when two molecules of urea combine with the loss of a molecule of ammonia. :2 NH2CONH2 → H2NCONHCONH2 + NH3 Normally this reaction is suppressed in the synthesis reactor by maintaining an excess of ammonia, but after the stripper, it occurs until the temperature is reduced. Biuret is undesirable in fertilizer urea because it is toxic to crop plants, although to what extent depends on the nature of the crop and the method of application of the urea. (Biuret is actually welcome in urea when is used as a cattle feed supplement). Isocyanic acid results from the thermal decomposition of ammonium cyanate, which is in chemical equilibrium with urea: :NH2CONH2 → NH4NCO → HNCO + NH3 This reaction is at its worst when the urea solution is heated at low pressure, which happens when the solution is concentrated for prilling or granulation (see below). The reaction products mostly volatilize into the overhead vapours, and recombine when these condense to form urea again, which contaminates the process condensate.


= Corrosion

= Ammonium carbamate solutions are notoriously corrosive to metallic construction materials, even more resistant forms of stainless steel—especially in the hottest parts of the plant such as the stripper. Historically corrosion has been minimized (although not eliminated) by continuous injection of a small amount of oxygen (as air) into the plant to establish and maintain a passivation (chemistry), passive oxide layer on exposed stainless steel surfaces. Because the
carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is ...

carbon dioxide
feed is recovered from
ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...

ammonia
synthesis gas, it contains traces of hydrogen that can mingle with passivation air to form an explosive mixture if allowed to accumulate. In the mid 1990s two duplex (ferritic-austenitic) stainless steels were introduced (DP28W, jointly developed by Toyo Engineering and Sumitomo Metals Industries and Safurex, jointly developed by Stamicarbon and Sandvik, Sandvik Materials Technology (Sweden).) These let manufactures drastically reduce the amount of passivation oxygen. In theory, they could operate with no oxygen. Saipem now uses either zirconium stripper tubes, or bimetallic tubes with a titanium body (cheaper but less erosion-resistant) and a metallurgically bonded internal zirconium lining. These tubes are fabricated by ATI Wah Chang (USA) using its Omegabond technique.


Finishing

Urea can be produced as prills, :wikt:granule, granules, pellets, crystals, and solutions.


= Solid forms

= For its main use as a fertilizer urea is mostly marketed in solid form, either as prills or granules. The advantage of prills is that, in general, they can be produced more cheaply than granules and that the technique was firmly established in industrial practice long before a satisfactory urea granulation process was commercialized. However, on account of the limited size of particles that can be produced with the desired degree of sphericity and their low crushing and impact strength, the performance of prills during bulk storage, handling and use is generally (with some exceptions) considered inferior to that of granules. High-quality compound fertilizers containing nitrogen co-granulated with other components such as phosphates have been produced routinely since the beginnings of the modern fertilizer industry, but on account of the low melting point and hygroscopic nature of urea it took courage to apply the same kind of technology to granulate urea on its own. But at the end of the 1970s three companies began to develop fluidized-bed granulation.


= UAN solutions

= In admixture, the combined solubility of ammonium nitrate and urea is so much higher than that of either component alone that it is possible to obtain a stable solution (known as UAN) with a total nitrogen content (32%) approaching that of solid ammonium nitrate (33.5%), though not, of course, that of urea itself (46%). Given the ongoing safety and security concerns surrounding fertilizer-grade solid ammonium nitrate, UAN provides a considerably safer alternative without entirely sacrificing the agronomic properties that make ammonium nitrate more attractive than urea as a fertilizer in areas with short growing seasons. It is also more convenient to store and handle than a solid product and easier to apply accurately to the land by mechanical means.


Laboratory preparation

Ureas in the more general sense can be accessed in the laboratory by reaction of phosgene with primary or secondary amines: : COCl2 + 4 RNH2 → (RNH)2CO + 2 RNH3Cl These reactions proceed through an isocyanate intermediate. Non-symmetric ureas can be accessed by the reaction of primary or secondary amines with an isocyanate. Urea can also be produced by heating ammonium cyanate to 60 °C. :NH4OCN → (NH2)2CO


Historical process

Urea was first noticed by Herman Boerhaave in the early 18th century from evaporates of urine. In 1773, Hilaire Rouelle obtained crystals containing urea from human urine by evaporating it and treating it with alcohol in successive filtrations. This method was aided by Carl Wilhelm Scheele's discovery that urine treated by concentrated nitric acid precipitated crystals. Antoine François, comte de Fourcroy and Louis Nicolas Vauquelin discovered in 1799 that the nitrated crystals were identical to Rouelle's substance and invented the term "urea." Berzelius made further improvements to its purification and finally William Prout, in 1817, succeeded in obtaining and determining the chemical composition of the pure substance. In the evolved procedure, urea was precipitated as urea nitrate by adding strong nitric acid to urine. To purify the resulting crystals, they were dissolved in boiling water with charcoal and filtered. After cooling, pure crystals of urea nitrate form. To reconstitute the urea from the nitrate, the crystals are dissolved in warm water, and barium carbonate added. The water is then evaporated and anhydrous alcohol added to extract the urea. This solution is drained off and evaporated, leaving pure urea.


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 bond, hydrogen-bonded urea molecules. This behaviour can be used to separate mixtures, e.g., in the production of aviation fuel and lubricating oils, and in the separation of hydrocarbons. As the helices are interconnected, all helices in a crystal must have the same stereoisomerism, 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 protonates readily. It is also a Lewis base forming complexes of the type [M(urea)6]n+. Molten urea decomposes into
ammonia Ammonia is a compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fort ...

ammonia
gas and isocyanic acid: : → + HNCO Via isocyanic acid, heating urea converts to a range of condensation reaction, condensation product including
biuret Biuret is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. Al ...

biuret
, triuret, guanidine, and melamine: : + HNCO → In aqueous solution, urea slowly equilibrates with ammonium cyanate. This hydrolysis cogenerates isocyanic acid, which can carbamide, carbamylate proteins. Urea reacts with malonic acid, malonic esters to make barbituric acids.


Etymology

''Urea'' is New Latin from French ''urée'', from Ancient Greek οὖρον ''ouron'', "urine".


See also

* Wöhler synthesis, Wöhler urea synthesis * Thiourea


References


External links

* {{Authority control Nitrogen cycle Ureas, Functional groups Excretion Soil improvers Fertilizers Urea cycle Lymph fluid Commodity chemicals Household chemicals E-number additives Organic compounds with 1 carbon atom