Hydrogen peroxide–urea

Names
IUPAC name Hydrogen peroxide–urea (1/1)
Systematic IUPAC name Peroxol–carbonyl diamide (1/1)
Other names Urea peroxide, percarbamide, UHP
Identifiers
CAS Number	124-43-6 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:75178
ChemSpider	29034 Y
ECHA InfoCard	100.004.275
PubChem CID	31294
UNII	31PZ2VAU81 Y
CompTox Dashboard (EPA)	DTXSID9024726
InChI InChI=1S/CH4N2O.H2O2/c2-1(3)4;1-2/h(H4,2,3,4);1-2H Y Key: AQLJVWUFPCUVLO-UHFFFAOYSA-N Y
SMILES O=C(N)N.OO
Properties
Chemical formula	CH6N2O3
Molar mass	94.070 g·mol−1
Appearance	White solid
Density	1.50 g/cm3
Melting point	75 to 91.5 °C (167.0 to 196.7 °F; 348.1 to 364.6 K) (decomposes)
Pharmacology
ATC code	D02AE01 (WHO)
Hazards
GHS labelling:[1]
Pictograms
Signal word	Danger
Hazard statements	H272, H315, H318
Precautionary statements	P210, P220, P264, P280, P302+P352, P305+P351+P338
Flash point	60 °C (140 °F; 333 K)
Safety data sheet (SDS)	External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Hydrogen peroxide–urea (also called Hyperol, artizone, urea hydrogen peroxide, and UHP) is a white crystalline solid chemical compound composed of equal amounts of hydrogen peroxide and urea. It contains solid and water-free hydrogen peroxide, which offers a higher stability and better controllability than liquid hydrogen peroxide when used as an oxidizing agent. Often called carbamide peroxide in dentistry, it is used as a source of hydrogen peroxide when dissolved in water for bleaching, disinfection and oxidation.

For the preparation of the complex, urea is dissolved in 30% hydrogen peroxide (molar ratio 2:3) at temperatures below 60 °C. upon cooling this solution, hydrogen peroxide–urea precipitates in the form of small platelets.^[2]

Akin to water of crystallization, hydrogen peroxide cocrystallizes with urea with the stoichiometry of 1:1. The compound is simply produced (on a scale of several hundred tonnes a year) by the dissolution of urea in excess concentrated hydrogen peroxide solution, followed by crystallization.^[3] The laboratory synthesis is analogous.^[4]

The solid state structure of this adduct has been determined by neutron diffraction.^[5]

Hydrogen peroxide–urea is a readily water-soluble, odorless, crystalline solid, which is available as white powder or colorless needles or platelets.^[2] Upon dissolving in various solvents, the 1:1 complex dissociates back to urea and hydrogen peroxide. So just like hydrogen peroxide, the (erroneously) so-called adduct is an oxidizer but the release at room temperature in the presence of catalysts proceeds in a controlled manner. Thus the compound is suitable as a safe substitute for the unstable aqueous solution of hydrogen peroxide. Because of the tendency for thermal decomposition, which accelerates at temperatures above 82 °C,^[6] it should not be heated above 60 °C, particularly in pure form.

The solubility of commercial samples varies from 0.05 g/mL^[7] to more than 0.6 g/mL.^[8]

Hydrogen peroxide–urea is mainly used as a disinfecting and bleaching agent in cosmetics and pharmaceuticals.^[3] As a drug, this compound is used in some preparations for the whitening of teeth.^[3][9][10] It is also used to relieve minor inflammation of gums, oral mucosal surfaces and lips including canker sores and dental irritation,^[11] and to emulsify and disperse earwax.^[12]

Carbamide peroxide is also suitable as a disinfectant, e.g. for germ reduction on contact lens surfaces or as an antiseptic for mouthwashes, ear drops or for superficial wounds and ulcers.

In the laboratory, it is used as a more easily handled replacement for hydrogen peroxide.^[4][13][14] It has proven to be a stable, easy-to-handle and effective oxidizing agent which is readily controllable by a suitable choice of the reaction conditions. It delivers oxidation products in an environmentally friendly manner and often in high yields especially in the presence of organic catalysts such as cis-butenedioic anhydride^[15] or inorganic catalysts such as sodium tungstate.^[16]

It converts thiols selectively to disulfides,^[15] secondary alcohols to ketones,^[16] sulfides to sulfoxides and sulfones,^[17] nitriles to amides,^[17][18] and N-heterocycles to amine oxides.^[17][19]

Hydroxybenzaldehydes are converted to dihydroxybenzenes (Dakin reaction)^[17][20] and give, under suitable conditions, the corresponding benzoic acids.^[20]

It oxidizes ketones to esters, in particular cyclic ketones, such as substituted cyclohexanones^[21] or cyclobutanones^[22] to give lactones (Baeyer–Villiger oxidation).

The epoxidation of various alkenes in the presence of benzonitrile yields oxiranes in yields of 79 to 96%.^[23]

The oxygen atom transferred to the alkene originates from the peroxoimide acid formed intermediately from benzonitrile. The resulting imidic acid tautomerizes to the benzamide.

The compound acts as a strong oxidizing agent and can cause skin irritation and severe eye damage.^[24] Urea–hydrogen peroxide was also found to be an insensitive high explosive, capable of detonation by strong impulse under heavy confinement.^[25][26]

• Sodium percarbonate
• Peroxide-based bleach

• "Hydrogen peroxide urea adduct, UHP". Organic Chemistry Portal.
• "Carbamide Peroxide Monograph". Drugs.com.