Urea is a very important industrial production which is much used in agricultural field as a fertilizer because urea contains high percentage of nitrogen. Urea dissolves very well in water. Urea is called also as carbamide, which is an organic compound with chemical formula of CO(NH2)2. Urea is a white solid.
Urea is an amide compound and has two -NH2 groups connecting to the carbonyl group.
In this tutorial, we first discuss urea manufacturing process, raw materials, reactions and uses of urea. Then study some useful reactions of urea.
Liquid ammonia is allowed to react with liquid carbon dioxide in a reactor at high temperature and pressure. The conditions employed are 130-1500C and a pressure of 35 atm. urea is formed in two-step reactions.
Ammonia and carbon dioxide react together and give ammonium carbamate (NH2COONH4)
Fast, Exothermic , Go to completeness at industrial situations.
Slow, Endothermic , does not go to completeness.
Manufactured urea contains unreacted ammonia and carbon dioxide and ammonium carbamate. Ammonium carbamate is removed by reducing the pressure (Le Chatelier's Principle). When heating, ammonia and carbon dioxide is separated. The advantage of this process is ammonia and carbon dioxide can be recycled back to the process.
Urea is obtained as a solution, but that solution is concentrated to give 99.6% molten urea, and granulated for use for fertilizer.
Ammonia and sodium carbonate are given as products by the reaction of urea and NaOH.
Urea and formaldehyde (HCOH) react in acidic medium to give urea-formaldehyde polymer. urea-formaldehyde polymer is very firm and used to manufacture wood adhesives.
CO2, N2, and H2O are the products of reaction of urea and nitrous acid (HNO2).
An amide, carbon dioxide, and ammonia are given as the products after reacting urea with carboxylic acids.
Urea production may cause several environmental pollution problems. These problems occur due to poor maintenance of the plant, leakages of toxic materials and more.
India is the top country of urea production. China, Indonesia, Russia, Qatar are the next other countries of urea production.
Ammonia is the most toxic material used in the urea manufacturing. Carbon dioxide is not much dangerous when it compares with ammonia. But it causes to increase the temperature of the environment.
Urea cannot be produced by a single reaction. It requires two steps reactions to get the product. First, ammonium carbamate is produced and next ammonium carbomate decomposes to urea and water.