Urea CAS：57-13-6

Urea possesses a flat molecular structure in its crystalline state, yet the nitrogen atoms take on a pyramidal shape in its lowest-energy gas-phase form. 

This unique structural duality gives rise to its special physical and chemical characteristics. 

In solid urea, the oxygen atom forms two N-H-O hydrogen bonds, creating a compact and thermodynamically stable hydrogen-bond network. This network disrupts ideal molecular stacking, resulting in an open framework composed of ribbon-like structures that form square-shaped channel cavities. 

The carbon atom in urea is sp² hybridized, which gives the C-N bonds significant double-bond characteristics. Meanwhile, the carbonyl oxygen in urea shows stronger basicity compared to that in formaldehyde and similar compounds. 

Urea dissolves readily in water because it can form extensive hydrogen bonds with water molecules, making it widely applicable in numerous industrial and chemical applications.

In mammals, urea functions as a key substance that regulates the excretion of nitrogen from the body. Produced in the liver during the decomposition of proteins, it is eventually removed from the body through urinary excretion. 

Urea also exists naturally in the skin, where it acts as both a moisturizing ingredient and a diuretic compound. In practical applications, urea is widely used to denature proteins and serves as a mild solubilizer for insoluble or denatured protein samples. It is especially effective in refolding proteins from materials denatured by 6 M guanidine chloride, such as inclusion bodies. 

Moreover, urea can be combined with guanidine hydrochloride and dithiothreitol (DTT) to help denatured proteins refold back into their natural and active structures.

Application of Urea

A stabilizer in nitrocellulose explosive
A component of animal feed, providing a relatively cheap source of nitrogen to promote growth
A non-corroding alternative to rock salt for road de-icing, and the resurfacing of snowboarding half pipes and terrain parks
A flavor-enhancing additive for cigarettes
A main ingredient in hair removers such as Nair or Veet
A browning agent in factory-produced pretzels
An ingredient in some hair conditioners, facial cleansers, bath oils, skin softeners, and lotions
A reactant in some ready-to-use cold compresses for first-aid use, due to the endothermic reaction it creates when mixed with water
A cloud seeding agent, along with other salts
A flame-proofing agent, commonly used in dry chemical fire extinguisher charges such as the urea-potassium bicarbonate mixture.
An ingredient in many tooth whitening products
An ingredient in dish soap
Along with ammonium phosphate, as a yeast nutrient, for fermentation of sugars into ethanol
A nutrient used by plankton in ocean nourishment experiments for geoengineering purposes
As an additive to extend the working temperature and open time of hide glue
As a solubility-enhancing and moisture-retaining additive to dye baths for textile dyeing or printing

Urea Chemical Properties

Safety Information