Urea CAS ：57-13-6
Molecular Structure: Urea molecules form a planar configuration in the crystalline state. In contrast, nitrogen atoms within urea take on a pyramidal spatial arrangement at the minimum energy state in the gas phase, which is the fundamental structural basis for its unique physical and chemical properties.
Hydrogen Bonding: In the solid state, the oxygen atom of urea can form two stable N-H-O hydrogen bonds. This intermolecular interaction constructs a compact and robust hydrogen bond network, effectively enhancing the structural stability of urea molecules.
High Aqueous Solubility: Urea features excellent water solubility. This characteristic stems from its ability to generate abundant hydrogen bonds with water molecules, making it a versatile chemical substance widely applied in industrial production and chemical research fields.
Urea exhibits a planar molecular framework under crystalline conditions, while its nitrogen atoms adopt a pyramidal spatial configuration in the minimum-energy gas-phase structure. Such structural duality is responsible for the unique physicochemical traits of urea molecules. In the solid state, the oxygen site of urea participates in the formation of two N-H-O hydrogen bonds, constructing a compact and thermodynamically stable hydrogen-bond network. Nevertheless, this intermolecular bonding pattern may disrupt the closest packing of molecular units, thereby generating an open structural morphology composed of ribbon-like arrangements that create square-cross-section tunnel architectures.
The central carbon atom of urea is sp² hybridized, which imparts significant double-bond properties to the C-N linkages. Moreover, the carbonyl oxygen of urea possesses stronger basicity compared with that of formaldehyde and other analogous compounds. The superior water solubility of urea originates from its ability to establish abundant intermolecular hydrogen bonds with water solvents. This outstanding solvation capability renders urea a multifunctional reagent with widespread applications in industrial manufacturing and chemical synthesis.
Urea Chemical Properties
Melting point | 132-135 °C(lit.) |
Boiling point | 332.48°C (estimate) |
density | 1.335 g/mL at 25 °C(lit.) |
vapor pressure | <0.1 hPa (20 °C) |
refractive index | n20/D 1.40 |
storage temp | 2-8°C |
solubility | H2O: 8 M at 20 °C |
form | |
pka | 0.10(at 25℃) |
color | white |
Specific Gravity | 1.335 |
Odor | almost odorless |
PH | 8.0-10.0 (20℃, 8M in H2O) |
Water Solubility | 1080 g/L (20 ºC) |
λmax | λ: 260 nm Amax: 0.03 |
Merck | 14,9867 |
BRN | 635724 |
Dielectric constant | 3.5（Ambient） |
Stability | Substances to be avoided include strong oxidizing agents. Protect from moisture. |
InChIKey | XSQUKJJJFZCRTK-UHFFFAOYSA-N |
LogP | -1.660 (est) |
CAS DataBase Reference | 57-13-6(CAS DataBase Reference) |
NIST Chemistry Reference | Urea(57-13-6) |
EPA Substance Registry System | Urea (57-13-6) |
Safety Information
Hazard Codes | Xn,Xi |
Risk Statements | 36/37/38-40-38 |
Safety Statements | 26-36-24/25-37 |
RIDADR | Not regulated |
WGK Germany | 1 |
RTECS | YR6250000 |
TSCA | Yes |
HS Code | 31021010 |
Hazardous Substances Data | 57-13-6(Hazardous Substances Data) |
Toxicity | LD50 orally in Rabbit: 8471 mg/kg LD50 dermal Rat 8200 mg/kg |
In mammalian organisms, urea functions as a key regulatory substance for nitrogen metabolic excretion. Produced in the liver during the catabolic breakdown of proteins, this metabolic end product is eventually eliminated from the body via urinary excretion. Naturally existing in human skin tissues, urea performs two major physiological functions, acting as both a moisturizing emollient and a diuretic substance. In biochemical practical applications, urea is commonly applied to induce protein denaturation and serves as a mild solubilizer for insoluble and denatured protein samples. It is especially suitable for the renaturation of proteins derived from samples denatured by 6 M guanidine chloride, with inclusion bodies being a typical application scenario. Furthermore, combined with guanidine hydrochloride and dithiothreitol (DTT), urea can facilitate the refolding process of denatured proteins, helping them recover their natural spatial structures and biological activity.
