Carbamide peroxide, also called urea peroxide, urea hydrogen peroxide (UHP), and percarbamide, an adduct

Adduct

An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species...

 of hydrogen peroxide

Hydrogen peroxide

Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

 and urea

Urea

Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

. Like hydrogen peroxide

Hydrogen peroxide

Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

, it is an oxidizer. This compound is a white crystalline solid which dissolves in water to give free hydrogen peroxide; the solubility of commercial samples varies from 0.05 g/mL to more than 0.6 g/mL. The chemical formula is .

Production

This compound is cheaply available; it is produced on a scale of several hundred tonnes a year by the dissolution of urea

Urea

Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....

 in excess concentrated hydrogen peroxide

Hydrogen peroxide

Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

 solution, followed by crystallization

Crystallization

Crystallization is the process of formation of solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas. Crystallization is also a chemical solid–liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid...

. The laboratory synthesis is analogous.

Applications

Carbamide peroxide is mainly used as a disinfecting and bleaching agent in cosmetics and pharmaceuticals. As a drug, this compound is used in some preparations for the whitening of teeth

Tooth bleaching

Dental bleaching, also known as tooth whitening, is a common procedure in general dentistry but most especially in the field of cosmetic dentistry. A child's deciduous teeth are generally whiter than the adult teeth that follow. As a person ages the adult teeth often become darker due to changes in...

. It is also used to relieve minor inflammation of gums, oral mucosal surfaces and lips including canker sores and dental irritation, and to emulsify and disperse ear wax.

In tooth bleaching, the hydrogen peroxide produced acts to oxidise interprismatic extrinsic staining within tooth enamel

Tooth enamel

Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...

. There are several methods of applying the peroxide gel to the tooth ranging from night-guard application at home or in-surgery application. The bleaching obtained is proportional to the length of time the peroxide is applied to the tooth, and the concentration used. Concentrations used for tooth whitening purposes range between 10% and 35%. Higher concentrations carry a higher risk of side effects such as chemical burns. 10% is widely regarded as safe.

A pharmaceutical company, Elorac

Elorac

Elorac, Inc. is a specialty pharmaceutical company focused on advancing treatments in dermatology. It is based in Vernon Hills, Illinois. According to the company’s website, Elorac specializes in prescription based dermatology products, with a focus on medications used in the treatment of...

, has performed clinical trials for the use of carbamide peroxide for the treatment of acne vulgaris

Acne vulgaris

Acne vulgaris is a common human skin disease, characterized by areas of skin with seborrhea , comedones , papules , pustules , Nodules and possibly scarring...

.

In the laboratory, it is used as a more easily handled replacement for hydrogen peroxide

Hydrogen peroxide

Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

.

Safety

As an oxidizer, this compound is a skin, eye and respiratory irritant. At higher concentrations, it is corrosive and may cause burns if not used properly. If too much gel is used and let in contact with skin or gums, there is a risk of white chemical burn

Chemical burn

A chemical burn occurs when living tissue is exposed to a corrosive substance such as a strong acid or base. Chemical burns follow standard burn classification and may cause extensive tissue damage. The main types of irritant and/or corrosive products are: acids, bases, oxidizers, solvents,...

s called blanching.

External links

• http://www.organic-chemistry.org/chemicals/oxidations/hydrogenperoxide-urea-adduct.shtm