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Hydrogen peroxide–urea

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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.

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
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.004.275 Edit this at Wikidata
UNII
  • InChI=1S/CH4N2O.H2O2/c2-1(3)4;1-2/h(H4,2,3,4);1-2H checkY
    Key: AQLJVWUFPCUVLO-UHFFFAOYSA-N checkY
  • O=C(N)N.OO
Properties
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
D02AE01 (WHO)
Hazards
GHS labelling:[1]
GHS03: OxidizingGHS05: Corrosive
Danger
H272, H315, H318
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).
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Production

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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]

Structure and properties

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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]

Applications

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Disinfectant and bleaching agent

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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.

Reagent in organic synthesis

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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]

 
Reaktionen mit Carbamidperoxid

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]

 
Reaktionen von Methoxyphenolen mit UHP

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

 
Baeyer-Villiger-Oxidation mit UHP

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]

 
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

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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]

See also

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References

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  1. ^ GHS: Sigma-Aldrich 289132
  2. ^ a b C.-S. Lu; E.W. Hughes; P.A. Giguère (1941), "The crystal structure of the urea-hydrogen peroxide addition compound CO(NH2)2 H2O2", J. Am. Chem. Soc., vol. 63, no. 6, pp. 1507–1513, doi:10.1021/ja01851a007
  3. ^ a b c Harald Jakob; Stefan Leininger; Thomas Lehmann; Sylvia Jacobi; Sven Gutewort. "Peroxo Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_177.pub2. ISBN 978-3527306732.
  4. ^ a b Yu, Lei; Meng, Bo; Huang, Xian (2008). "Urea-Hydrogen Peroxide Complex: A Selective Oxidant in the Synthesis of 2-Phenylselenyl-1,3-butadienes". Synthetic Communications. 38 (18): 3142. doi:10.1080/00397910802109224. S2CID 98323467.
  5. ^ Fritchie, C. J. Jr.; McMullan, R. K. (1981). "Neutron Diffraction Study of the 1:1 Urea:Hydrogen Peroxide complex at 81 K". Acta Crystallographica Section B. 37 (5): 1086. doi:10.1107/S0567740881005116.
  6. ^ H. Heaney; F. Cardona; A. Goti; A.L. Frederick (2013). "Hydrogen Peroxide-Urea". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rh047.pub3. ISBN 978-0471936237. {{cite book}}: |periodical= ignored (help)
  7. ^ Sigma-Aldrich specification sheet
  8. ^ Chemicalland data sheet
  9. ^ Mokhlis, G. R.; Matis, B. A.; Cochran, M. A.; Eckert, G. J. (2000). "A Clinical Evaluation of Carbamide Peroxide and Hydrogen Peroxide Whitening Agents during Daytime Use". Journal of the American Dental Association. 131 (9): 1269–77. doi:10.14219/jada.archive.2000.0380. PMID 10986827. Archived from the original on 2013-02-23.
  10. ^ Toothwhitening Archived 2008-03-17 at the Wayback Machine from the UMD of New Jersey website
  11. ^ Center for Integrative Medicine: Carbamide Peroxide from the University of Maryland Medical Center website Archived October 18, 2007, at the Wayback Machine
  12. ^ "Ear Drops GENERIC NAME(S): CARBAMIDE PEROXIDE". WebMD. Retrieved July 3, 2021.
  13. ^ Varma, Rajender S.; Naicker, Kannan P. (1999). "The Urea−Hydrogen Peroxide Complex: Solid-State Oxidative Protocols for Hydroxylated Aldehydes and Ketones (Dakin Reaction), Nitriles, Sulfides, and Nitrogen Heterocycles". Organic Letters. 1 (2): 189. doi:10.1021/ol990522n.
  14. ^ Harry Heaney, Francesca Cardona, Andrea Goti, "Hydrogen Peroxide–Urea" Encyclopedia of Reagents for Organic Synthesis 2008. doi:10.1002/047084289X.rh047.pub2
  15. ^ a b B. Karami; M. Montazerozohori; M. H. Habibi (2005), "Urea-Hydrogen Peroxide (UHP) oxidation of thiols to the corresponding disulfides promoted by maleic anhydride as mediator" (PDF), Molecules (in German), vol. 10, no. 10, pp. 1358–1363, doi:10.3390/10101385, PMC 6147623, PMID 18007530
  16. ^ a b M. Lukasiewicz; D. Bogdal; J. Pielichowski. "Microwave-assisted oxidation of alcohols using urea hydrogen peroxide". 8th International Electronic Conference on Synthetic Organic Chemistry. ECSOC-8. Retrieved 2016-05-10.
  17. ^ a b c d R.S. Varma, K.P. Naicker, "The Urea-Hydrogen Peroxide Complex: Solid-State Oxidative Protocols for Hydroxylated Aldehydes and Ketones (Dakin Reaction), Nitriles, Sulfides, and Nitrogen Heterocycles", Org. Lett. (in German), vol. 1, no. 2, pp. 189–191, doi:10.1021/ol990522n
  18. ^ WO patent 2012069948, V. Mascitti, K.F. McClure, M.J. Munchhof, R.P. Robinson, Jr., "4-(5-Cyano-pyrazol-1-yl)-piperidine derivatives as GPR 119 modulators", issued 2012-5-31, assigned to Pfizer Inc. 
  19. ^ D. Rong; V.A. Phillips; R.S. Rubio; M.A. Castro; R.T. Wheelhouse, "A safe, convenient and efficient method for the preparation of heterocyclic N-oxides using urea-hydrogen peroxide", Tetrahedron Lett. (in German), vol. 49, no. 48, pp. 6933–6935, doi:10.1016/j.tetlet.2008.09.124
  20. ^ a b H. Heaney; A.J. Newbold (2001), "The oxidation of aromatic aldehydes by magnesium monoperoxyphthalate and urea-hydrogen peroxide", Tetrahedron Lett. (in German), vol. 42, no. 37, pp. 6607–6609, doi:10.1016/S0040-4039(01)01332-6
  21. ^ M.Y. Rios; E. Salazar; H.F. Olivo (2007), "Baeyer–Villiger oxidation of substituted cyclohexanones via lipase-mediated perhydrolysis utilizing urea–hydrogen peroxide in ethyl acetate", Green Chem. (in German), vol. 9, no. 5, pp. 459–462, doi:10.1039/B618175A
  22. ^ A. Watanabe; T. Uchida; K. Ito; T. Katsuki (2002), "Highly enantioselective Baeyer-Villiger oxidation using Zr(salen) complex as catalyst", Tetrahedron Lett. (in German), vol. 43, no. 25, pp. 4481–4485, doi:10.1016/S0040-4039(02)00831-6
  23. ^ L. Ji; Y.-N. Wang; C. Qian; X.-Z. Chen (2013), "Nitrile-promoted alkene epoxidation with urea-hydrogen peroxide (UHP)", Synth. Commun. (in German), vol. 43, no. 16, pp. 2256–2264, doi:10.1080/00397911.2012.699578, S2CID 93770740
  24. ^ "Hydrogen peroxide urea SDS". merckmillipore.com. 16 May 2023.
  25. ^ Halleux, Francis; Pons, Jean-François; Wilson, Ian; Van Riet, Romuald; Lefebvre, Michel (2022). "Small-Scale Detonation of Industrial Urea-Hydrogen Peroxide (UHP)". Propellants, Explosives, Pyrotechnics. 47 (2). doi:10.1002/prep.202100250. hdl:1826/17469. S2CID 244899815.
  26. ^ Halleux, Francis; Pons, Jean-François; Wilson, Ian; Simoens, Bart; Van Riet, Romuald; Lefebvre, Michel (2023). "Detonation performance of urea-hydrogen peroxide (UHP)". Propellants, Explosives, Pyrotechnics. 48 (6). doi:10.1002/prep.202300011. S2CID 257196173.
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