H2NCONH2, melting point 135°C. A colourless solid, manufactured by heating ammonia and carbon dioxide under pressure: 2NH3 + CO2 ? H2NCONH2 + H2O; also called carbamide. Although excreted in the urine of mammals, it is used as an animal feed additive as well as a fertilizer. It is the starting material for urea resins.
| Urea | |
|---|---|
| General | |
| Systematic name | Diaminomethanal |
| Other names | ? |
| Molecular formula | (NH2)2CO |
| SMILES | NC(=O)N |
| Molar mass | 60.07 g/mol |
| Appearance | white odourless solid |
| CAS number | [57-13-6] |
| Properties | |
| Density and phase | 750 kg/m3 |
| 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) |
| Melting point |
132.7 °C (406 K) decomposes |
| Boiling point | n.a. |
| Acidity (pKa) | 0.18 |
| Basicity (pKb) | 13.82 |
| Chiral rotation [α]D | Not chiral |
| Viscosity | ? °C |
| Critical relative humidity |
81% (20°C) 73% (30°C) |
| Heat of solution in water | -57,8 cal/g (endothermic) |
| Nitrogen content | 46,6 %N |
| Structure | |
| Molecular shape | ? |
| Coordination geometry | trigonal planar |
| Crystal structure | ? |
| Dipole moment | ? D |
| Hazards | |
| MSDS | J.T. Baker |
| Main hazards | ? |
| Flash point | ? °C |
| R/S statement | R: ? |
| RTECS number | ? |
| NFPA 704 | estimated |
| Supplementary data page | |
| Structure & properties | n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other anions | ? |
| Other cations | ? |
| Related ? |
biuret triuret thiourea |
| Related compounds | ? |
|
Except where noted otherwise, data are given for materials in their standard state (at 26°C, 100 kPa) Infobox disclaimer and references |
|
Urea is an organic compound of carbon, nitrogen, oxygen and hydrogen, with the formula CON2H4 or (NH2)2CO.
Physiology
The individual atoms of urea come from carbon dioxide, water, aspartate and ammonia in a metabolic pathway known as the urea cycle, an anabolic process.
The urea is formed in the livers of mammals in a cyclic pathway, from the break down of ammonia, (a metabolic waste), which was initially named the Krebs-Henseleit cycle after its discoverers, and later became known simply as the urea cycle.
Production
Urea is produced commercially from two raw materials, ammonia and carbon dioxide.
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.
Unconverted reactants can be used for the manufacture of other products, for example ammonium nitrate or sulphate, or they can be recycled for complete conversion to urea in a total-recycle process.
Clinical diagnosisSee blood urea nitrogen ("BUN") for a commonly performed urea test, and marker of renal function.
Other diagnostic useIsotopically-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 Helicobacter pylori (H.
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