{{Short description|Chemical compound}} {{Chembox | verifiedrevid = 420941219 | ImageFileL1 = Wasserstoffperoxid.svg | ImageClassL1 = skin-invert-image | ImageFileR1 = Harnstoff.svg | ImageClassR1 = skin-invert-image | ImageFile2 = H2O2-urea complex, code26444.png | ImageClass2 = bg-transparent | ImageAlt = | IUPACName = Hydrogen peroxide–urea (1/1) | PIN = | SystematicName = Peroxol–carbonic diamide (1/1) | OtherNames = {{ubl |Carbamide peroxide |Percarbamide |UHP |Urea peroxide }} | Section1 = {{Chembox Identifiers | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/CH4N2O.H2O2/c2-1(3)4;1-2/h(H4,2,3,4);1-2H | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = AQLJVWUFPCUVLO-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 124-43-6 | PubChem = 31294 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 29034 | ChEBI = 75178 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 31PZ2VAU81 | SMILES = O=C(N)N.OO }} | Section2 = {{Chembox Properties | Properties_ref = <ref name="SigmaSDS">{{cite web |url=https://www.sigmaaldrich.com/US/en/sds/aldrich/289132?userType=anonymous |title=SDS - Carbamide Peroxide |website=sigmaaldrich.com |publisher=Sigma-Aldrich |page=6 |date=8 September 2024 |access-date=17 October 2025}}</ref> | C=1 | H=6 | N=2 | O=3 | Formula = {{chem2|CO(NH2)2*H2O2}} | Appearance = White crystalline solid | Density = {{val|1.390|u=g/cm3}} at {{convert|20|C}} | MeltingPtC = 90 to 93 | MeltingPt_notes = (decomposes) | MeltingPt_ref = | BoilingPtC = 175.5 | BoilingPt_notes = (est.) | BoilingPt_ref = <ref name="ChembookSDS"/> | Solubility = {{val|0.5|u=g/mL}}<ref name="ChembookSDS"/> | LogP = -1.4<ref name="DrugBank">{{Cite web |vauthors=Knox C, Wilson M, Klinger CM, et al. |url=https://go.drugbank.com/drugs/DB11129#properties-header |title=Carbamide peroxide |publisher=DrugBank 6.0}}</ref> | pKa = 15.73<ref name="DrugBank"/> | VaporPressure = {{val|3110|u=Pa}} at {{convert|30|C}} | RefractIndex = }} | Section6 = {{Chembox Pharmacology | ATCCode_prefix = D02 | ATCCode_suffix = AE01 }} | Section5 = {{Chembox Explosive | Explosive_ref = <ref name="PEP2022"/> | ShockSens = | FrictionSens = | DetonationV = {{ubl | {{val|2897|u=m/s}} ({{val|0.75|u=g/cm3}}) | {{val|3517|u=m/s}} ({{val|0.9|u=g/cm3}}) | {{val|3647|u=m/s}} ({{val|1.0|u=g/cm3}}) | {{val|3860|u=m/s}} ({{val|1.1|u=g/cm3}}) }} | REFactor = }} | Section7 = {{Chembox Hazards | GHSPictograms = {{GHS03}}{{GHS05}} | GHSSignalWord = danger | HPhrases = {{HPhrases|272|315|318}} | PPhrases = {{PPhrases|210|220|264|280|302+352|305+351+338+310|332+313|362|370+378|501}} | GHS_ref = <ref>{{Sigma-Aldrich|id=289132|name=Carbamide peroxide}}</ref> | ExternalSDS = | FlashPtC = 93 | NFPA-F = 1 | NFPA-H = 3 | NFPA-R = 3 | NFPA-S = OX | NFPA_ref = <ref name="ChembookSDS">{{cite web |title=SDS - Urea Hydrogen Peroxide |url=https://www.chemicalbook.com/msds/urea-hydrogen-peroxide.pdf |website=chemicalbook.com |publisher=ChemicalBook |access-date=17 October 2025 |page=3 |date=1 February 2025}}</ref> | AutoignitionPtC = }} | Section9 = {{Chembox Related | OtherAnions = | OtherCations = | OtherFunction = | OtherFunction_label = | OtherCompounds = {{ubl |Hydrogen peroxide |Urea }} }} }} '''Hydrogen peroxide–urea''' (also called '''Hyperol''', '''artizone''', '''urea hydrogen peroxide''', and '''UHP''') is a white crystalline solid chemical compound composed of equimolar 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 and when used in over-the-counter ear drops, it is used as a source of hydrogen peroxide when dissolved in water for bleaching, disinfection and oxidation.<ref>{{cite web |author=<!-- not stated --> |date= 2026-05-17 |title= PubChem Compound Summary for CID 31294, Carbamide Peroxide |url=https://pubchem.ncbi.nlm.nih.gov/compound/Carbamide-Peroxide |publisher= National Center for Biotechnology Information |access-date=2025-05-23}}</ref>

== Production == For the preparation of the complex, urea is dissolved in 30% hydrogen peroxide (molar ratio 2:3) at temperatures below {{convert|60|C}}. upon cooling this solution, hydrogen peroxide–urea precipitates out in the form of small platelets.<ref name="Giguère">{{cite journal|first1=C.-S. |last1=Lu |first2=E.W. |last2=Hughes |first3=P.A. |last3=Giguère |journal=J. Am. Chem. Soc. |title=The crystal structure of the urea-hydrogen peroxide addition compound CO(NH<sub>2</sub>)<sub>2</sub> H<sub>2</sub>O<sub>2</sub> |volume=63 |issue=6 |pages=1507–1513 |year=1941 |doi=10.1021/ja01851a007}}</ref>

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.<ref name = Ullmann>{{Ullmann | title = Peroxo Compounds, Inorganic | author1 = Harald Jakob| author2 = Stefan Leininger| author3 = Thomas Lehmann| author4 = Sylvia Jacobi| author5 = Sven Gutewort | doi = 10.1002/14356007.a19_177.pub2}}</ref> The laboratory synthesis is analogous.<ref name="ReferenceA">{{cite journal | last1 = Yu | first1 = Lei | last2 = Meng | first2 = Bo | last3 = Huang | first3 = Xian | title = Urea-Hydrogen Peroxide Complex: A Selective Oxidant in the Synthesis of 2-Phenylselenyl-1,3-butadienes | journal = Synthetic Communications | volume = 38 | pages = 3142 | year = 2008 | doi = 10.1080/00397910802109224 | issue = 18| s2cid = 98323467 }}</ref>

==Structure and properties== The solid state structure of this adduct has been determined by neutron diffraction.<ref>{{Cite journal | first1 = C. J. Jr.|last1=Fritchie|first2= R. K.|last2 =McMullan | journal = Acta Crystallographica Section B | year = 1981 | volume = 37 | pages = 1086 | doi = 10.1107/S0567740881005116 | title = Neutron Diffraction Study of the 1:1 Urea:Hydrogen Peroxide complex at 81 K | issue = 5|bibcode=1981AcCrB..37.1086F }}</ref>

Hydrogen peroxide–urea is a readily water-soluble, odorless, crystalline solid, which is available as white powder or colorless needles or platelets.<ref name="Giguère" /> Upon dissolving in various solvents, the 1:1 complex dissociates back to urea and hydrogen peroxide. So just like hydrogen peroxide, the 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 safer substitute for the unstable aqueous solution of hydrogen peroxide. Because of the tendency for thermal decomposition, which accelerates at temperatures above {{convert|82|C}},<ref name="e-EROS">{{cite book |first1=H. |last1=Heaney |first2 =F. |last2=Cardona |first3=A. |last3=Goti |first4=A.L. |last4=Frederick |chapter=Hydrogen Peroxide-Urea |doi=10.1002/047084289X.rh047.pub3|title=Encyclopedia of Reagents for Organic Synthesis|year=2013|isbn=978-0471936237}}</ref> it should not be heated above {{convert|60|C}}, particularly in pure form.{{cn|date=October 2025}}

==Applications==

===Disinfectant and bleaching agent=== Hydrogen peroxide–urea is mainly used as a disinfecting and bleaching agent in cosmetics and pharmaceuticals.<ref name = Ullmann/> As a drug, this compound is used in some preparations for the whitening of teeth.<ref name=Ullmann/><ref name="ADA-CP-HP">{{cite journal |last1=Mokhlis |first1=G. R. |last2=Matis |first2=B. A. |last3=Cochran |first3=M. A. |last4=Eckert |first4=G. J. |title=A Clinical Evaluation of Carbamide Peroxide and Hydrogen Peroxide Whitening Agents during Daytime Use |pages=1269–77 |issue=9 |volume=131 |journal=Journal of the American Dental Association |url=http://jada.ada.org/cgi/content/full/131/9/1269 |archive-url=http://web.archive.org/web/20090218152418/http://jada.ada.org:80/cgi/content/full/131/9/1269 |url-status=dead |archive-date= 2009-02-18|year=2000 |pmid=10986827 |doi=10.14219/jada.archive.2000.0380|url-access=subscription}}</ref><ref>{{cite web |url=http://dentalschool.umdnj.edu/patients/dental-bytes.htm |title=Toothwhitening |archive-url=https://web.archive.org/web/20080317074054/http://dentalschool.umdnj.edu/patients/dental-bytes.htm |archive-date=2008-03-17 |publisher=UMD of New Jersey |website=dentalschool.umdnj.edu}}</ref> It is also used to relieve minor inflammation of gums, oral mucosal surfaces and lips including canker sores and dental irritation,<ref name="ummc">{{cite web |url=http://www.umm.edu/altmed/drugs/carbamide-peroxide-021300.htm |title=Center for Integrative Medicine: Carbamide Peroxide |publisher=University of Maryland Medical Center |website=www.umm.edu |archive-url=https://web.archive.org/web/20071018153839/http://www.umm.edu/altmed/drugs/carbamide-peroxide-021300.htm |archive-date=October 18, 2007 }}</ref> and to emulsify and disperse earwax.<ref name="WebMDeardrops">{{cite web |title=Ear Drops GENERIC NAME(S): CARBAMIDE PEROXIDE |url=https://www.webmd.com/drugs/2/drug-153293/ear-drops-carbamide-peroxide-otic-ear/details |publisher=WebMD |access-date=July 3, 2021}}</ref>

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.

===Reagent in organic synthesis=== In the laboratory, it is used as a more easily handled replacement for hydrogen peroxide.<ref name="ReferenceA"/><ref name="Varma">{{cite journal |first1=R.S. |last1=Varma |first2=K.P. |last2=Naicker |journal=Organic Letters |title=The Urea-Hydrogen Peroxide Complex: Solid-State Oxidative Protocols for Hydroxylated Aldehydes and Ketones (Dakin Reaction), Nitriles, Sulfides, and Nitrogen Heterocycles |volume=1 |issue=2 |pages=189–191 |doi=10.1021/ol990522n}}</ref><ref name="e-EROS"/><ref>{{cite journal|first1=Zhiguo J. |last1=Song|first2=Guoyue |last2=Zhou|first3=Honglin |last3=Ye|first4=Ryan |last4=Cohen |first5=Lushi |last5=Tan|title= Preparation of 9-Azabicyclo&#91;3.3.1&#93;nonane-N-oxyl (ABNO)|journal= Organic Syntheses|date= 2022|volume= 99|pages= 251–273|doi= 10.15227/orgsyn.099.0251}}</ref>

Its effectiveness is enhanced by organic catalysts ''cis''-butenedioic anhydride<ref name="Karami">{{cite journal |first1=B. |last1=Karami |first2=M. |last2=Montazerozohori |first3=M.H. |last3=Habibi |journal=Molecules |title=Urea-Hydrogen Peroxide (UHP) oxidation of thiols to the corresponding disulfides promoted by maleic anhydride as mediator |volume=10 |issue=10 |pages=1358–1363 |doi=10.3390/10101385 |pmid=18007530 |pmc=6147623 |date=31 October 2005 |doi-access=free}}</ref> or inorganic catalysts such as sodium tungstate.<ref name="Lukasiewicz">{{cite conference |title=Microwave-assisted oxidation of alcohols using urea hydrogen peroxide |conference=8th International Electronic Conference on Synthetic Organic Chemistry. ECSOC-8 |url=https://www.mdpi.org/ecsoc/ecsoc-8/MAS/003/ |accessdate=17 October 2025 |first1=M. |last1=Lukasiewicz |first2=D. |last2=Bogdal |first3=J. |last3=Pielichowski |date=November 2004}}</ref>

500px|center|Reaktionen mit Carbamidperoxid

It converts thiols selectively to disulfides,<ref name="Karami" /> secondary alcohols to ketones,<ref name="Lukasiewicz" /> sulfides to sulfoxides and sulfones,<ref name="Varma"/> nitriles to amides,<ref name="Varma" /><ref>{{cite patent |country=WO |status=patent |number=2012069948 |title=4-(5-Cyano-pyrazol-1-yl)-piperidine derivatives as GPR 119 modulators |gdate=2012-5-31 |inventor=V. Mascitti, K.F. McClure, M.J. Munchhof, R.P. Robinson, Jr. |assign=Pfizer Inc.}}</ref> and ''N''-heterocycles to amine oxides.<ref name="Varma" /><ref>{{cite journal |first1=D. |last1=Rong |first2=V.A. |last2=Phillips |first3=R.S. |last3=Rubio |first4=M.A. |last4=Castro |first5=R.T. |last5=Wheelhouse |journal=Tetrahedron Letters |title=A safe, convenient and efficient method for the preparation of heterocyclic N-oxides using urea-hydrogen peroxide |volume=49 |issue=48 |pages=6933–6935 |doi=10.1016/j.tetlet.2008.09.124}}</ref>

700px|center|Reaktionen von Methoxyphenolen mit UHP

Hydroxybenzaldehydes are converted to dihydroxybenzenes (Dakin reaction)<ref name="Varma" /><ref name="Heaney">{{cite journal |first1=H. |last1=Heaney |first2=A.J. |last2=Newbold |journal=Tetrahedron Letters |title=The oxidation of aromatic aldehydes by magnesium monoperoxyphthalate and urea-hydrogen peroxide |volume=42 |issue=37 |pages=6607–6609 |doi=10.1016/S0040-4039(01)01332-6|year=2001}}</ref> and give, under suitable conditions, the corresponding benzoic acids.<ref name="Heaney" />

300px|center|Baeyer-Villiger-Oxidation mit UHP

It oxidizes ketones to esters, in particular cyclic ketones, such as substituted cyclohexanones or cyclobutanones to give lactones (Baeyer–Villiger oxidation).<ref name="Rios">{{cite journal |first1=M.Y. |last1=Rios |first2=E. |last2=Salazar |first3=H.F. |last3=Olivo |journal=Green Chemistry |title=Baeyer–Villiger oxidation of substituted cyclohexanones via lipase-mediated perhydrolysis utilizing urea–hydrogen peroxide in ethyl acetate |volume=9 |issue=5 |pages=459–462 |doi=10.1039/B618175A |year=2007}}</ref><ref>{{cite journal |last1=Watanabe |first1=Akira |last2=Uchida |first2=Tatsuya |last3=Ito |first3=Katsuji |last4=Katsuki |first4=Tsutomu |title=Highly enantioselective Baeyer–Villiger oxidation using Zr(salen) complex as catalyst |journal=Tetrahedron Letters |date=June 2002 |volume=43 |issue=25 |pages=4481–4485 |doi=10.1016/S0040-4039(02)00831-6}}</ref>

The epoxidation of various alkenes in the presence of benzonitrile yields oxiranes in yields of 79 to 96%.<ref>{{cite journal |last1=Ji |first1=Li |last2=Wang |first2=Ya-Na |last3=Qian |first3=Chao |last4=Chen |first4=Xin-Zhi |title=Nitrile-Promoted Alkene Epoxidation with Urea–Hydrogen Peroxide (UHP) |journal=Synthetic Communications |date=18 August 2013 |volume=43 |issue=16 |pages=2256–2264 |doi=10.1080/00397911.2012.699578 |s2cid=93770740}}</ref>

300px|center|Epoxidierung von Cyclohexen mit UHP

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

== Safety == The compound acts as a strong oxidizing agent and can cause skin irritation and severe eye damage.<ref name="SigmaSDS"/>

Urea–hydrogen peroxide was also found to be an insensitive but moderately powerful secondary explosive.<ref name="PEP2022">{{cite journal|title=Small-Scale Detonation of Industrial Urea-Hydrogen Peroxide (UHP)|journal=Propellants, Explosives, Pyrotechnics|year=2022 |doi=10.1002/prep.202100250 |last1=Halleux |first1=Francis |last2=Pons |first2=Jean-François |last3=Wilson |first3=Ian |last4=Van Riet |first4=Romuald |last5=Lefebvre |first5=Michel |volume=47 |issue=2 |hdl=1826/17469 |s2cid=244899815|hdl-access=free }}</ref><ref>{{cite journal|doi=10.1002/prep.202300011 |title=Detonation performance of urea-hydrogen peroxide (UHP) |year=2023 |last1=Halleux |first1=Francis |last2=Pons |first2=Jean-François |last3=Wilson |first3=Ian |last4=Simoens |first4=Bart |last5=Van Riet |first5=Romuald |last6=Lefebvre |first6=Michel |journal=Propellants, Explosives, Pyrotechnics |volume=48 |issue=6 |hdl=1826/19229 |s2cid=257196173 |hdl-access=free }}</ref>

==See also== * Sodium percarbonate * Peroxide-based bleach

==References== {{reflist|2}}

==External links== * {{cite web |url=https://www.organic-chemistry.org/chemicals/oxidations/hydrogenperoxide-urea-adduct.shtm |title=Hydrogen peroxide urea adduct, UHP |publisher=Organic Chemistry Portal}} * {{cite web |url=https://www.drugs.com/monograph/carbamide-peroxide.html |title=Carbamide Peroxide Monograph |publisher=Drugs.com}}

Category:Bleaches Category:Antiseptics Category:Cleaning product components Category:Ureas Category:Peroxides Category:Oxidizing agents Category:Hydrogen peroxide Category:Explosive chemicals