Tag: urea

The first is carbamate formation: the fast exothermic reaction of liquid ammonia with gaseous carbon dioxide at high temperature and pressure to form ammonium carbamate (${ H } _{ 2 }N-COO-N{ H } _{ 4 }$).

 $2N{ H } _{ 3 }+C{ O } _{ 2 }\rightleftharpoons { H } _{ 2 }N-COO-N{ H } _{ 4 }$

More than 90% of world industrial production of urea is destined for use as a nitrogen-release fertilizer. Urea has the highest nitrogen content of all solid nitrogenous fertilizers in common use. Therefore, it has the lowest transportation costs per unit of nitrogen nutrient.

Ammonium carbamate is a salt formed by the reaction of ammonia with carbon dioxide or carbamic acid. This compound is a white solid that is extremely soluble in water, soluble in alcohol, and only slightly volatile at room temperature. It is prepared by the direct reaction between liquid ammonia and dry ice (solid carbon dioxide).

Biuret is a chemical compound with the chemical formula ${ C } _{ 2 }{ H } _{ 5 }{ N } _{ 3 }{ O } _{ 2 }$. It is also known as carbamylurea. It is the result of condensation of two molecules of urea and is an impurity in urea-based fertilizers.

The most common impurity of synthetic urea is biuret, which impairs plant growth. 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.

The ability of ammonium carbamate to make urea was first discovered in 1870 by Bassarov when he heated ammonium carbamate in sealed glass tubes at temperatures ranging from 130 to 140 $℃$. This yields urea and water in an equimolar ratio. A typical industrial plant that makes urea can produce up to 1500 tons a day. Ammonia and carbon dioxide is excessively fed to a synthesis reactor in this process. Ammonium carbamate is produced as an intermediate in this reactor and can then be dehydrated to urea according to the following equation.

${ H } _{ 2 }N-COON{ H } _{ 4 }→N{ H } _{ 2 }CON{ H } _{ 2 }+{ H } _{ 2 }O$

Wohler's synthesis is used for the preparation of urea. In this reaction ammonium cyanate is transformed into urea.
$\displaystyle NH _4(NCO) \rightarrow NH _3 + HNCO \rightarrow (NH _2) _2CO$

Biuret is a chemical compound with the chemical formula ${ C } _{ 2 }{ H } _{ 5 }{ N } _{ 3 }{ O } _{ 2 }$. It is also known as carbamylurea. It is the result of condensation of two molecules of urea and is an impurity in urea-based fertilizers.

The most common impurity of synthetic urea is biuret, which impairs plant growth. 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.

When soybean meal and other plant proteins are high in price, more urea is used to replace plant protein in the ration of beef cattle and sheep. Urea is a non-protein nitrogen (NPN) compound.