Ammonium carbamate

Ammonium carbamate

White solid with ammoniacal odor

Fixed

1.6 g · cm -3

152 ° C

Decomposition above 35 ° C

80 hPa (20 ° C)

Well in water (790 g · l-1 at 20 ° C)

Attention

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Ammonium carbamate, ammonium carbamate formerly also called, is the ammonium salt of carbamic acid, which is not known in a free state. It is a minor component of hartshorn.

Properties

Ammonium carbamate forms a colorless crystalline powder that is readily soluble in water ( about 790 g / l). By the addition of ammonia gas, the solubility is enhanced. In aqueous solution, ammonium carbamate is hydrolyzed from 35 ° C partially, above 60 ° C completely to form ammonium carbonate, which in turn can break down into ammonia and carbon dioxide. When heated in a closed system, the salt is transformed at a temperature above 130 ° C gradually into urea. The conversion rate increases with increasing temperature too strong, the water formed acts as a catalyst.

Synthesis

Ammonium carbamate is formed by direct reaction of ammonia gas and CO2 in a volume ratio of 2:1 in the absence of water.

Use

Ammonium carbamate used in the cosmetics industry and in the manufacture of pesticides. It is also an important intermediate in the production of urea. Another use of it as cleaning, pickling and neutralizing agents, as well as in the above -mentioned Hirschhornsalz for baking. In Germany, the direct production of ammonium carbamate is due to low demand, only about 1,000 t / a The automotive industry is examined as an alternative to ammonium carbamate urea solution AdBlue SCR catalysts.