Hydrogen peroxide–urea
{{Short description|Chemical compound}}
{{Chembox
| verifiedrevid = 420941219
| ImageFileL1 = Wasserstoffperoxid.svg
| ImageFileR1 = Harnstoff.svg
| ImageFile2 = H2O2-urea complex, code26444.png
| ImageAlt =
| IUPACName = Hydrogen peroxide–urea (1/1)
| PIN =
| SystematicName = Peroxol–carbonic diamide (1/1)
| OtherNames = Urea peroxide, percarbamide, UHP
| 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
| C=1 | H=6 | N=2 | O=3
| Appearance = White solid
| Density = 1.50 g/cm3
| MeltingPtC = 75 to 91.5
| MeltingPt_notes = (decomposes)
| BoilingPt =
| Solubility = }}
| Section6 = {{Chembox Pharmacology
| ATCCode_prefix = D02
| ATCCode_suffix = AE01
}}
| Section7 = {{Chembox Hazards
| GHSPictograms = {{GHS03}}{{GHS05}}
| GHSSignalWord = danger
| HPhrases = {{HPhrases|H272 | H315 | H318}}
| PPhrases = {{PPhrases|P210 | P220 | P264 | P280 | P302 + P352 | P305 + P351 + P338}}
| GHS_ref = GHS: [https://www.sigmaaldrich.com/product/ALDRICH/289132 Sigma-Aldrich 289132]
| ExternalSDS =[http://msds.chem.ox.ac.uk/CA/carbamide_peroxide.html External MSDS]
| FlashPtC = 93
| NFPA-F = 1
| NFPA-H = 3
| NFPA-R = 3
| NFPA-S = OX
| AutoignitionPtC = }}
}}
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, it is used as a source of hydrogen peroxide when dissolved in water for bleaching, disinfection and oxidation.
Production
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 out in the form of small platelets.{{citation| author1 =C.-S. Lu| author2 =E.W. Hughes| author3 = P.A. Giguère|periodical=J. Am. Chem. Soc.|title=The crystal structure of the urea-hydrogen peroxide addition compound CO(NH2)2 H2O2|volume=63|issue=6|pages=1507–1513|year=1941|doi=10.1021/ja01851a007}}
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.{{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}} The laboratory synthesis is analogous.{{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 }}
Structure and properties
The solid state structure of this adduct has been determined by neutron diffraction.{{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}}
Hydrogen peroxide–urea is a readily water-soluble, odorless, crystalline solid, which is available as white powder or colorless needles or platelets. 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 safer substitute for the unstable aqueous solution of hydrogen peroxide. Because of the tendency for thermal decomposition, which accelerates at temperatures above 82 °C,{{cite book| author1 =H. Heaney| author2 =F. Cardona| author3 =A. Goti| author4 =A.L. Frederick|periodical=E-EROS Encyclopedia of Reagents for Organic Synthesis|chapter=Hydrogen Peroxide-Urea|doi=10.1002/047084289X.rh047.pub3|title=Encyclopedia of Reagents for Organic Synthesis|year=2013|isbn=978-0471936237}} it should not be heated above 60 °C, particularly in pure form.
The solubility of commercial samples varies from 0.05 g/mL[http://www.sigmaaldrich.com/catalog/product/aldrich/289132 Sigma-Aldrich specification sheet] to more than 0.6 g/mL.[http://chemicalland21.com/industrialchem/inorganic/UREA%20HYDROGEN%20PEROXIDE.htm Chemicalland data sheet]
Applications
=Disinfectant and bleaching agent=
Hydrogen peroxide–urea 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.{{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=https://archive.today/20130223065123/http://jada.ada.org/cgi/content/full/131/9/1269
|url-status=dead
|archive-date=2013-02-23
|year=2000
|pmid=10986827
|doi=10.14219/jada.archive.2000.0380
|url-access=subscription
}}[http://dentalschool.umdnj.edu/patients/dental-bytes.htm Toothwhitening] {{Webarchive|url=https://web.archive.org/web/20080317074054/http://dentalschool.umdnj.edu/patients/dental-bytes.htm |date=2008-03-17 }} from the UMD of New Jersey website It is also used to relieve minor inflammation of gums, oral mucosal surfaces and lips including canker sores and dental irritation,[http://www.umm.edu/altmed/drugs/carbamide-peroxide-021300.htm Center for Integrative Medicine: Carbamide Peroxide] from the University of Maryland Medical Center website {{webarchive |url=https://web.archive.org/web/20071018153839/http://www.umm.edu/altmed/drugs/carbamide-peroxide-021300.htm |date=October 18, 2007 }} and to emulsify and disperse earwax.{{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}}
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.{{cite journal | last1 = Varma | first1 = Rajender S. | last2 = Naicker | first2 = Kannan P. | title = The Urea−Hydrogen Peroxide Complex: Solid-State Oxidative Protocols for Hydroxylated Aldehydes and Ketones (Dakin Reaction), Nitriles, Sulfides, and Nitrogen Heterocycles | journal = Organic Letters | volume = 1 | pages = 189 | year = 1999 | doi = 10.1021/ol990522n | issue = 2}}Harry Heaney, Francesca Cardona, Andrea Goti, "Hydrogen Peroxide–Urea" Encyclopedia of Reagents for Organic Synthesis 2008. {{doi|10.1002/047084289X.rh047.pub2}} 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{{citation| author1 =B. Karami| author2 =M. Montazerozohori| author3 = M. H. Habibi|periodical=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|language=German|doi=10.3390/10101385|pmid=18007530|pmc=6147623|url=http://www.mdpi.org/molecules/papers/10101358.pdf|year=2005|doi-access=free}} or inorganic catalysts such as sodium tungstate.{{cite web|title=Microwave-assisted oxidation of alcohols using urea hydrogen peroxide|trans-title=|periodical=8th International Electronic Conference on Synthetic Organic Chemistry. ECSOC-8|publisher=|url=http://www.usc.es/congresos/ecsoc/8/MAS/003/index.htm|accessdate=2016-05-10|author1=M. Lukasiewicz |author2=D. Bogdal |author3=J. Pielichowski |date=|year=|language=English|pages=|quote=}}
File:Reaktionsübersicht Carbamidperoxid.svg
It converts thiols selectively to disulfides, secondary alcohols to ketones, sulfides to sulfoxides and sulfones,{{citation|surname1=R.S. Varma, K.P. Naicker|periodical=Org. Lett.|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|language=German|doi=10.1021/ol990522n}} nitriles to amides,{{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.}} and N-heterocycles to amine oxides.{{citation| author1 =D. Rong| author2 =V.A. Phillips| author3 =R.S. Rubio| author4 =M.A. Castro| author5 =R.T. Wheelhouse|periodical=Tetrahedron Lett.|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|language=German|doi=10.1016/j.tetlet.2008.09.124}}
File:Umsetzung Methoxyphenole mit UHP.svg
Hydroxybenzaldehydes are converted to dihydroxybenzenes (Dakin reaction){{citation| author1 =H. Heaney| author2 =A.J. Newbold|periodical=Tetrahedron Lett.|title=The oxidation of aromatic aldehydes by magnesium monoperoxyphthalate and urea-hydrogen peroxide|volume=42|issue=37|pages=6607–6609|language=German|doi=10.1016/S0040-4039(01)01332-6|year=2001}} and give, under suitable conditions, the corresponding benzoic acids.
File:Baeyer-Villiger-Oxidation mit Cyclobutanonen.svg
It oxidizes ketones to esters, in particular cyclic ketones, such as substituted cyclohexanones{{citation| author1 =M.Y. Rios| author2 =E. Salazar| author3 =H.F. Olivo|periodical=Green Chem.|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|language=German|doi=10.1039/B618175A|year=2007}} or cyclobutanones{{citation| author1 =A. Watanabe| author2 = T. Uchida| author3 = K. Ito| author4 =T. Katsuki|periodical=Tetrahedron Lett.|title=Highly enantioselective Baeyer-Villiger oxidation using Zr(salen) complex as catalyst|volume=43|issue=25|pages=4481–4485|language=German|doi=10.1016/S0040-4039(02)00831-6|year=2002}} to give lactones (Baeyer–Villiger oxidation).
The epoxidation of various alkenes in the presence of benzonitrile yields oxiranes in yields of 79 to 96%.{{citation| author1 =L. Ji| author2 =Y.-N. Wang| author3 =C. Qian| author4 =X.-Z. Chen|periodical=Synth. Commun.|title=Nitrile-promoted alkene epoxidation with urea-hydrogen peroxide (UHP)|volume=43|issue=16|pages=2256–2264|language=German|doi=10.1080/00397911.2012.699578|year=2013|s2cid=93770740}}
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.{{cite web|url=https://www.merckmillipore.com/GB/en/product/msds/MDA_CHEM-818356|title=Hydrogen peroxide urea SDS|website=merckmillipore.com| date=16 May 2023}} Urea–hydrogen peroxide was also found to be an insensitive but powerful secondary explosive.{{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 |url=http://dspace.lib.cranfield.ac.uk/handle/1826/17469 }}{{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 }}
See also
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}}