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Application and synthetic method Nitrogen fertilizer Application Methods Ruminant feed additive Solubility in water (g /100ml) Identification test Content analysis Toxicity Limited use Food additive, maximal allowed usage, maximal allowed residue Chemical property Uses Production method

CAS No.57-13-6
Chemical Name:Urea
Molecular Formula:CH4N2O
Formula Weight:60.06
MOL File:57-13-6.mol
Urea Property
Melting point : 132-135 °C(lit.)
density : 1.335 g/mL at 25 °C(lit.)
refractive index : n20/D 1.40
storage temp. : 2-8°C
solubility : H2O: 8 M at 20 °C
form : powder
color : white
Water Solubility : 1080 g/L (20 ºC)
Merck : 14,9867
BRN : 635724
Stability:: Substances to be avoided include strong oxidizing agents. Protect from moisture.
CAS DataBase Reference: 57-13-6(CAS DataBase Reference)
NIST Chemistry Reference: Urea(57-13-6)
EPA Substance Registry System: Urea(57-13-6)
Hazard Codes : Xn,Xi
Risk Statements : 36/37/38-40
Safety Statements : 26-36-24/25
WGK Germany : 1
RTECS : YR6250000
HS Code : 31021010
Hazardous Substances Data: 57-13-6(Hazardous Substances Data)

Urea Chemical Properties,Usage,Production

Application and synthetic method
Urea is one kind of the final products of protein metabolism in mammals and human. It is also a major organic nitrogen compound excreted by animal body. Pure product is white granular or needle-like crystal. It exhibits pink or yellow when being mixed with iron and other heavy metals. It is tasteless, odorless, and easily soluble in water, ethanol and benzene, but insoluble in ether and chloroform. At 20 °C, 100 kg water is able to dissolve 105 kg urea. Urea is endothermic when being dissolved. Its aqueous solution is neutral. The nitrogen content of pure product is 46.65%, is 42%-46% for that of agricultural urea which contains a small amount of biuret (typically less than 2%) with no harm to the crop. Both the specific gravity and bulk density are small, with 0.65 tons of fertilizer per cubic meter.
Urea, when presented at a temperature below 20 °C and at a relative humidity less than 70%, not only does not absorb moisture, but also even cause water evaporation which will reduce its moisture content; when the temperature exceeds 20 °C and the relative humidity is above 80%, urea begins to absorb moisture, even becomes paste-like in severe case, and re-agglomerate upon dry air, which is second only to ammonium nitrate. The aqueous solution, when placed at 80 °C, will have hydrolysis and decomposition reactions and generate carbamate, ammonia, and carbon dioxide, respectively. Under acidic and alkaline conditions, the decomposition of urea will be accelerated when exposed to heat.
Urea is easy to bind to linear carbohydrate compound to crystal-like adduct; it reacts with various inorganic compounds to form: Ca (NO3) 2 ·4CO (NH2) 2, NH4Cl ·CO (NH2) 2, CaSO4 ·4CO (NH2) 2, MgSO4 ·4CO (NH2) 2 ·3H2O, and Mg (NO3) ·4CO (NH2) 2 ·2H2O; it is easy to react with calcium phosphate to produce urea phosphate, dicalcium phosphate and water, namely Ca (H2PO4) 2 ·H2O + CO (NH2) 2 → H3PO4 ·CO (NH2) 2 + CaHPO4 + H2O; and the is easy to form urea nitrate upon reaction with nitrate, namely CO (NH2) 2 + HNO3 → CO (NH2) 2 ·HNO3; can generate urea formaldehyde compounds upon reaction with formaldehyde (urea acid plastic), wherein the one with a high proportion of formaldehyde named urea resin while the one with a low proportion of formaldehyde should be slowly-release (efficacy) urea.
Nitrogen fertilizer
Urea is a high-quality, efficiency, and important nitrogen fertilizer. At the end of World War I, Germany had begun to applied urea as a fertilizer. Practice has proved that urea has high nitrogen content and has no sub-component. It has a good efficacy on increasing yield on all crops. After the 1950s, it had become the focus of the development of nitrogen fertilizers in different countries. During the 15 years between 1960 and 1975, the global urea production had increased by 10.5 times, and had gradually replaced the ammonium nitrate to become the world’s mostly applied nitrogen fertilizer since the 1970s. When applied into the soil, a small portion of urea is absorbed by plants in the form of amide, and the rest big portion is undergone ammoniation process to become ammonia by ammoniated urease, and then be absorbed by plants. Its decomposition rate depends on the the soil, temperature and water content; it generally lasts for 3 to 10 days, and making urea’s fertilizer efficacy longer than other kinds of fertilizer. Moreover, the loss of nitrogen content is relative mild. Urea is an ideal fertilizer of foliar application because it does not contain ingredients harmful to crops, and is neutral without burning the stem and leaves. It is hygroscopic and easy to penetrate into leaves together with water to be rapidly absorbed by crops. The concentration of foliar application is generally 0.5% to 2%. To improve the efficacy of urea utilization, besides correctly grasp the nature and application conditions, you should also pay attention to proper administration.
Urea is a neutral fertilizer without containing any harmful ingredients. It hydrolysis products, NH4+ and HCO3-can both be absorbed by crops. Continuous administration year after year generally causes no adverse effects on the nature of the soil. It is suitable for variety of crops and soil. Its efficacy is similar with that of ammonium sulfate containing equal content of nitrogen. It can be applied for deteriorated paddy fields which are easy to subject to hydrogen sulfide poisoning due to a lack of active iron and has a better effect than ammonium sulfate. Excessive application of urea or having very high biuret content is easy to cause ammonia and biuret poisoning; the higher the crops urease activity become, the higher sensitivity the crops will have to the urea and biuret poisoning.
Urea can be used as the feed supplements for ruminant animal. Industrial urea is the raw material for synthesizing urea-formaldehyde, melamine-formaldehyde resins. It is also used for the synthesis of some drugs such as tetracycline, Phenobarbital and caffeine. Dye industry also apply it to produce Vat Brown BR and phthalocyanine blue B.
Urea should be wrapped by plastic film inside and packaged by woven bag outside. It should be stored in dry warehouse and not allowed for mutual storage or shipment with acids.
Application Methods
Application methods of urea include basal fertilizer, seed fertilizer or foliage top-dressing. The application of basal fertilizer and seed fertilizer, the more time should be 4 to 5 days earlier than that of ammonium nitrogen fertilizer. The administered amount should be reduced together with the nitrogen content. When using urea as base fertilizer of paddy field, we should apply plow immediately after application at 5 to 7 days before water irrigation. Don’t irrigate too early after application in order to reduce the direct loss of urea; when used for foliage top-dressing, first apply water to the surface of the field and maintain shallow layer; plow immediately after fertilization, and maintained for 2 to 3 days without irrigation. The method of application of urea as basal and foliage top-dressing of dry land is quite similar with that of a variety of ammonium nitrogen fertilizer. Urea is generally not directly used as seed fertilizer, due to high concentration and pH of urea or ammonia for fertilization which can lead to protein denaturation and thus hinder the seed germination and seedling growth, even make the seeds completely lost germination ability. This negative effect on small seed is particularly great; but if we mix urea first with dry fine soil and apply at a certain depth under the seed, and cover with thin soil before sowing; or apply urea to the side of the seed with a distance of 2.5 cm, there would be no adverse effects on seed germination.
The leaves of common crops generally absorb urea crops faster than root. Urea has a better effect when used for foliage top-dressing than the other kinds of fertilizers, the reason is as below: 1. urea is a neutral organic nitrogen compound without containing non-sub-component. Common dosage of the solution for the spray has a small burning effect on crop leaf. 2. Small degree of ionization, molecular size is small, easy to enter into the leaf cells through the cell membrane. 3. Urea molecule has relatively high penetration and diffusion rate, thus plasmolysis is not easy to occur at the time of cell penetration, and also easy to restore even plasmolysis. 4. Itself has a strong moisture absorption ability. Solid urea generated from the residue with water evaporated after the can still re-dissolved by moisture absorption, and thus having higher absorption efficiency. The suitable concentration for foliage application of urea depends on the crop species and growth stages. Generally, optimal concentration for spraying of rice, wheat and grasses is 2.0%; for cucumber, it is 1.0% to 1.5%; for radish, cabbage, spinach and cabbage, it is 1.0%; for watermelon, eggplant, sweet potato, potato, peanut and citrus, it is 0.4% to 0.8%; for mulberry, tea, pears, apples and grapes, it is 0.5%; for persimmons, tomatoes, strawberries, greenhouse cucumber and eggplant, flowers, it is 0.2% to 0.3%. Usually spray once every 7 to 10 days with a total of 2 to 3 times. The amount of the solution should be 750 to 1125 kg per hectare per time. Spray to the foliage till moist is suitable. Spraying time is more suitable in early morning or evening. For foliage top-dressing of urea, the biuret content should not be higher than 0.5% to prevent leaves from being hurt.
Ruminant feed additive
At the early 1940s, the United States began to add urea in the feed of ruminant livestock. After 50s, the urea had been worldwide applied as a non-protein nitrogen sources for ruminants. In the late 1980s, the total amount of urea used for feed in US reached 100 million tons, equivalent to about 5 percent of the US total production of urea. China, in the early 1990s, has a total urea output of about 600 million tons with the amount of feed accounting for about 2% to 3%.
Urea is mainly used for feeding cattle, sheep and other ruminants. There is rare case of scientific reports that monogastric animals can make use of urea. To ensure the rational and efficient application and prevent the increase of pH value in livestock rumen and the occurrence of ammonia poisoning, the use of urea as feed should be considered for the following several points: 1. Mix uniformly and limit intake amount. Don’t drink immediately after taking feed containing urea. 2. Daily diet should contain a certain amount of easily fermentable carbohydrates, in which the best is molasses with starch, dextrin being second, while cellulosic feed is good. 3. Supply proper and balanced amount of minerals, with particular attention to the supplement of cobalt, zinc, sulfur to meet the demands of rumen microorganisms multiply. 4. Daily diet should not be mixed with urease-containing feed, such as raw beans, raw soybean meal. 5. Gradually increase urea fed for livestock and their pups that have been subject to urea feed for the first time or have been fed with only forage and hay before so that they can gradually adapt to it. 6. Urea can be used at daily diet of both high-energy & low protein and low energy & low protein diet low protein. However, the efficiency of utilization for urea upon at both low energy & high-protein and high energy & high-protein diets is poor. Appropriate amount of urea should be determined by the fermentation value of urea.
Urea poisoning occurs fast with a short duration, usually appears within 10 minutes to several hours after feeding. Clinical symptoms: irritability, tremor, a large number of salivation, shortness of breath, uncoordinated muscle movement, swelling, and convulsions. Usually feed six liters of 5% acetate solution can bind to ammonia to prevent excess ammonia from entering into the bloodstream.
Solubility in water (g /100ml)
Dissolved amount (in grams) per 100 ml of water at different temperatures (°C):
108g/20 °C; 167g/40 °C; 251g/60 °C; 400g/80 ℃; 733g/100 °C
Identification test
Solubility: easily soluble in water and soluble in ethanol (OT-42).
Nitric acid precipitation test: dissolve 0.1 g sample in water, add 1ml of concentrated nitric acid. There should be a white crystalline precipitate appear.
Colorimetric reaction: take 1 g sample in a test tube; heat for liquefaction, and cool when turbidity happens in the solution; dissolve it in a mixture of 10 mL water and l mL 2mol/L NaOH; add 0.05 mL of copper sulfate test solution (TS-78) and reddish purple color should appear.
Melting range: 132~135 °C.
Content analysis
Accurately weigh sample of about 0.5g, dissolve it in 10% sulfuric acid solution and dilute to l00 mL. Take 5 mL of liquid and add it into a long-necked Molotov cocktail; add 10 mL of sulfuric acid test solution (TS-240), carefully heat it until no further evaporation of gas. Carefully boil for 10 mins, and carefully add 40ml of water after cooling. After cooling again, place it in a steam distiller. Add 50 mL of 10mol/L NaOH solution and carefully distill it for 1 hour with the vapor being continuously sent into mixture. Collect about 50 mL of distillate and add them into a collection bottle containing 40 mL of 4% (W/V) boric acid solution. Add 25 mL of methyl red/methylene blue test solution (TS-150), apply titration using 0.1 mol/L hydrochloric acid. Perform a blank titration at the same time with every mL of 0.1 mol/L hydrochloric acid being equivalent to 3.003 mg of urea (CH4N2O).
The above information is edited by the Chemicalbook of Dai Xiongfeng.
GRAS (FDA§184.1923, 2000).
LD50:14300 mg/kg (rat, oral).
You can use gum with a concentration lower than 3% without toxicity (FAO/WHO, 2001).
Limited use
Without limitation (FDA§184.1923, 2000).
Food additive, maximal allowed usage, maximal allowed residue
Food additive, maximal allowed usage, maximal allowed residue
Chemical property
It is a colorless crystal; soluble in water, ethanol and benzene; almost insoluble in ether and chloroform.
1. Used for separating nitrous oxide, nitrous acid and chromatography; also used as biological growth agents.
2. Used for the raw material of fertilizers, animal feed, explosives, stabilizers and the preparation of urea-formaldehyde resin.
3. Urea is an important raw material in the production of pesticides. It can be used for making fungicides such as cymoxanil, ethirimol, pesticides triazophos, phosalone, pyrimidines oxychloride, fenitrothion nitrile, tetramethrin, and some herbicides.
4. Used for the nitrogen fertilizer in agriculture; used as feed additives in industry; used for making explosives, stabilizers, and urea-formaldehyde resins, etc.
5. A crop fertilizer for improving the utilization of nitrogen content in urea.
6. Yeast food; gum tissue modifiers. GB2760-90 listed it as a processing aid for making alcoholic beverages, clear rubber products, wine, and yeast-fermented baked goods.
7. Urea is mainly used as fertilizer. In industry, it is also used as the raw materials for making urea-formaldehyde resin, polyurethane, and melamine-formaldehyde resin. It also has wide applications in medicine, explosives, leather, flotation agents, pigments and petroleum products dewaxing. Urea is heated at 200 °C to generate solid trimer acid (cyanuric acid). The derivatives of trimer acid such as TCCA, dichloroisocyanurate sodium cyanate, isocyanurate tris (2-hydroxyethyl), isocyanurate tris (allyl) ester, tris (3,5-di tert-butyl-4-hydroxybenzyl) isocyanate, iso-cyanuric acid triglycidyl ether, melamine cyanurate complexes have many important applications. The first two are the novel high-grade disinfection and bleach agents. The toal capacity of TCCA in the world exceeds over 80,000 t.
Chemical Properties
White crystalline powder
Used for the denaturation of proteins and as a mild solubilization agent for insoluble or denatured proteins. Useful for renaturing proteins from samples already denatured with 6 M guanidine chloride such as inclusion bodies. May be used with guanidine hydrochloride and dithiothreitrol (DTT) in the refolding of denatured proteins into their native or active form.
anticholelithogenic; LD50(rat) 890 mg/kg ip
Urea is a physiological regulator of nitrogen excretion in mammals; synthesized in the liver as an end-product of protein catabolism and excreted in urine. Also occurs normally in skin. Emollient; diu retic.
Production method
1. Urea is the final product of urea in protein metabolism in the mammalian. In 1922, it is realized in German that using combination of carbon dioxide and ammonia for industrial urea synthesis. Ammonia and carbon dioxide can react to generate a carbamate amine, and then dehydrated to generate urea.
2. Use carbon dioxide and ammonia for synthesis of carbamate at high temperature, high pressure conditions; Go through decomposition, absorption, transformation, crystallization, separation, and drying to get the final product.
3. The preparation method is using purified ammonia and carbon dioxide at a molar ratio of 2.8 to 4.5 for mix before entering into the synthesis column; Keep the column pressure at 13.8~24.6 MPa and temperature at 180~200 °C, and the residence time of mass reaction for 25~40min, to generate urea solution with excess amount of ammonia and ammonium carbamate; go through vacuum cooling, and evaporate over 99.5% of the urea after being separated from ammonia and ammonium carbamate, and then get the finished product in urea granulation tower granulation.
General Description
Solid odorless white crystals or pellets. Density 1.335 g /cc. Noncombustible.
Air & Water Reactions
Water soluble.
Reactivity Profile
Urea is a weak base. Reacts with hypochlorites to form nitrogen trichloride which explodes spontaneously in air [J. Am. Chem. Soc. 63:3530-32]. Same is true for phosphorus pentachloride. Urea reacts with azo and diazo compounds to generate toxic gases. Reacts with strong reducing agents to form flammable gases (hydrogen). The heating of improper stoichiometric amounts of Urea and sodium nitrite lead to an explosion. Heated mixtures of oxalic acid and Urea yielded rapid evolution of gases, carbon dioxide, carbon monoxide and ammonia (if hot, can be explosive). Titanium tetrachloride and Urea slowly formed a complex during 6 weeks at 80°C., decomposed violently at 90°C., [Chem. Abs., 1966, 64, 9219b]. Urea ignites spontaneously on stirring with nitrosyl perchlorate, (due to the formation of the diazonium perchlorate). Oxalic acid and Urea react at high temperatures to form toxic and flammable ammonia and carbon monoxide gasses, and inert CO2 gas [Von Bentzinger, R. et al., Praxis Naturwiss. Chem., 1987, 36(8), 41-42].
Health Hazard
May irritate eyes.
Fire Hazard
Behavior in Fire: Melts and decomposes, generating ammonia.
Urea Preparation Products And Raw materials
Raw materials
Liquefied petroleum ges HEAVY CUT RESIDUE OIL Glycine CARBON DIOXIDE 2,2'-Iminodiethanol METALLURGICAL COKE PETROLEUM ETHER Vanadium pentoxide Acetic acid glacial AMMONIUM CARBAMATE Ammonia
Preparation Products
Reactive Black KN-BN ureaformaldelyde resin UF 5-CARBETHOXYURACIL 2,4-DICHLOROTHIENO[3,2-D]PYRIMIDINE DIHYDROTHYMINE Furacilin Tanning agent for white leather synthetic carbamider ring tanning agent No.1 1-(2-Aminoethyl)imidazolidin-2-one DIRECT FAST BLACK G Carbachol 5,6-DIHYDROURACIL Pigment Yellow 65 6-Aminouracil flame retardane ZR-01 Thieno[3,2-d]pyrimidine, 2,4-dichloro- 2,6-Dichloro-4,8-dipiperidinopyrimidino[5,4-d]pyrimidine biodegrddable finishing agent for fabric BIUREA 1-(1,3-DIHYDRO-1-OXOISOBENZOFURAN-3-YL)UREA N,N''-(isobutylidene)diurea 1-Methyl-1-nitrosourea 4,5-dihydroxy-1,3-bis(hydroxymethyl)imidazolidin-2-one 3-Hydroxy-1-phenyl-1,2,4-triazole DICHLOROISOCYANURIC ACID Cymoxanil 2,4,6,8-Tetrahydroxy-Pyrimido-(5,4D)Pyrimidine Urea hydrogen peroxide 5-(sec-pentyl)barbituric acid Amino moulding plastic Tableware cleaner synthetic tanning agent PNC rubber latex 104T/C Biuret ETHYL 2-HYDROXYPYRIMIDINE-5-CARBOXYLATE 1-PHENYLSEMICARBAZIDE ALLYLUREA Water flush fertilizer 2-HYDROXY-4-PHENYLPYRIMIDINE-5-CARBOXYLIC ACID 2,4-DIHYDROXYTHIENO[3,2-D]PYRIMIDINE
Urea Suppliers      Global( 283)Suppliers     
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