Chemical Properties of Urea Preparation and Properties
→ Basic Nature : For strong acids, urea act as weak mono acidic base. The main reason for this property of mono acidic base of urea is its resonating structures.
→ Hydrolysis: Hydrolysis of urea take place with dilute acid, base and at high temperature.
→ Hydrolysis of urea takes place at normal temperature in the presence of enzyme urease.
→ From Nitrous acid : When urea treated with nitrous acid, it decomposes into nitrogen and carbondioxide gas.
→ From Sodium Hypobromite In the presence of alkaline sodium hypobromite (NaOBr) urea decomposes with release of nitrogen gas.
→ Carbon dioxide gets dissolve in basic medium. Hence, by measuring the volume of nitrogen gas released, amount and percentage of urea can be estimated.
→ From Dicarboxylic Acids : In the presence of phosphorous oxychioride, urea form a cyclic compound by reacting with dicarboxylic acids.
→ Urea reacts with malonic acid and form sleeping medicines barbituric acid or malonic urea.
→ Biuret Synthesis : When urea is heated slowly at 155°C, two molecules of urea react with release of ammonia and gives biuret, a white cystalline solid.
→ Above reaction is a test for urea because on adding alkaline solution of copper sulphate to white solid biuret, violet colour is obtained.
→ When urea is heated strongly at 17O°C cyanic acid is formed which then trimerises to form cyanuric acid.
→ From Hydrazne : Urea forms semicarbazide with hydrazine.
→ From Formaldehyde : In the presence of acid or base one molecule of urea reacts with two molecules of formaldehyde and form dimethylol tarea.