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| CAS
No 57-13-6 |
Synonyms
Diaminomethanal
Carbamide
E 927 b |
| Physical
data |
| Melting
point: 135°C |
Boiling
point:
Decomposes at about 150°C |
| Vapur
pressure: 1,73 kPa at 20°C (saturated water solution) |
Water solubility:
1080 g/l at 20°C |
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Urea is the diamide of carbonic acid. It consists of colourless,
odourless crystals with a bitter, cool, slightly salty taste. The word
comes from the greek word uron which means urine.
Carbamide comes from the latin carbo=coal and amide, which stands for
ammonium compounds. Urea was discovered in 1773 and first synthesized in
1828. This was the first synthesised organic compound made from an
inorganic compound. It was a deathblow to the theory that alleged
organic compounds could only be formed by a certain vital force.
Dissolved in water, it hydrolyzes very slowly to ammonium carbamate and
eventually decomposes to ammonia and carbon dioxide. This reaction is
the base for the use of urea as fertilizer. Urea acts as a monobasic
substance and forms salts with acids.
Urea is produced commercially from ammonia and carbon dioxide at high
pressure and temperature. Ammonium carbamate is formed which is
dehydrated to urea. In 2000 more than 100 million tonnes of urea were
produced worldwide. In Western Europe more than 5 million tonnes were
produced.
More than 90 % of the world production is destined for use as a
fertilizer. Other areas of use are de-icing of runways and roadways, as
raw material for manufacturing of melamine and urea-formaldehyde resin
used in plastics and glues, as a component of animal feed and in food
industry as an additive in ice-cream and chewing-gum. Urea is used in
cosmetics as a moisturizer. It is also used, together with salt, as a
cloud seeding agent and as a flame retardant.
Many tooth-whitening products contain carbamide peroxide which is
decomposed to urea and hydrogen peroxide. The consumption of urea for
urea-formaldehyde resins has decreased in recent years because hazardous
formaldehyde is slowly released from such resins. Urea is used to reduce
nitrogen oxides, NOx, to nitrogen in engine and combustion exhaust.
Urea is manufactured in Sweden from imported ammonia. It is mainly used
as fertilizer, in plastics and in resins for manufacture of wooden
products. It is an approved food additive called E 927b.
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