'''Hydrogen peroxide''' is a [[chemical compound]] with the formula {{chem|H|2|O|2}}. In its pure form it is a colorless [[liquid]], slightly more [[viscosity|viscous]] than [[water]]; however, for safety reasons it is normally used as an aqueous solution. Hydrogen peroxide is the simplest [[peroxide]] (a compound with an oxygen-oxygen [[single bond]]) and finds use as a strong [[oxidizer]], [[bleach]]ing agent and [[disinfectant]]. Concentrated hydrogen peroxide, or '[[high-test peroxide]],' is a [[reactive oxygen species]] and has been used as a [[propellant]] in [[rocket]]ry.<ref>{{Cite book| url = http://books.google.com/?id=AzoCJfTmRDsC | title =A Vertical Empire: The History of the UK Rocket and Space Programme, 1950–1971 | first = C. N. | last = Hill | publisher = Imperial College Press | year = 2001 | isbn = 978-1-86094-268-6}}</ref>
Hydrogen peroxide is often described as being “water but with one more oxygen atom” a description which can give the incorrect impression that there is a great deal of similarity between the two compounds. Pure hydrogen peroxide will explode if heated to boiling, will cause serious contact burns to the skin and can set materials alight on contact. For these reasons it is usually handled as a dilute solution (household grades are typically 3-6%). Its chemistry is dominated by the nature of its unstable [[peroxide]] bond.
==Structure and properties==
===Properties===
The boiling point of {{chem|H|2|O|2}} has been extrapolated as being 150.2 °C, approximately 50 degrees higher than water; in practice hydrogen peroxide will undergo potentially explosive [[thermal decomposition]] if heated to this temperature. It may be safely distilled under reduced pressure.<ref>{{cite book|last=Riley|first=edited by Georg Brauer ; translated by Scripta Technica, Inc. Translation editor Reed F.|title=Handbook of preparative inorganic chemistry. Volume 1|year=1963|publisher=Academic Press|location=New York, N.Y.|isbn=978-0121266011|page=140|edition=2nd}}</ref>
'''Hydrogen peroxide''' (H<sub>2</sub>O<sub>2</sub>) is a very pale blue liquid which appears colourless in a dilute solution, slightly more [[viscous]] than water. It is a weak [[acid]]. It has strong [[oxidation|oxidizing]] properties and is therefore a powerful [[bleaching agent]] that is mostly used for bleaching paper, but has also found use as a [[disinfectant]], as an [[oxidizer]], and in [[rocket]]ry (particularly in high concentrations as [[high-test peroxide]] (HTP) as a [[monopropellant]]), and in [[bipropellant]] systems.
====In aqueous solutions====
In [[aqueous]] solutions hydrogen peroxide differs from the pure material due to the effects of [[hydrogen bonding]] between water and hydrogen peroxide molecules. Hydrogen peroxide and water form a [[eutectic]] mixture, exhibiting [[freezing-point depression]]; pure water has a melting point of 0 °C and pure hydrogen peroxide of −0.43 °C, but a 50% (by volume) solution of the two freezes at -51 °C. The boiling point of the same mixtures is also depressed in relation with the median of both boiling points (125.1 °C). It occurs at 114 °C. This boiling point is 14° greater than that of pure water and 36.2° less than that of pure hydrogen peroxide.<ref>[http://www.h2o2.com/intro/FMC_MSDS_40_to_60.pdf 60% hydrogen peroxide msds 50% H2O2 MSDS]</ref>
==History==
{| class="wikitable" style="margin: 1em auto 1em auto;"
Hydrogen peroxide was first isolated in 1818 by [[Louis Jacques Thénard]] by reacting [[barium peroxide]] with [[nitric acid]]. An improved version of this process used [[hydrochloric acid]], followed by [[sulfuric acid]] to precipitate the [[barium sulfate]] byproduct. Thenard's process was used from the end of the 19th century until the middle of the 20th century.<ref>C. W. Jones, J. H. Clark. ''Applications of Hydrogen Peroxide and Deriatives''. Royal Society of Chemistry, '''1999'''.</ref> Modern production methods are discussed below.
|+ '''Density of aqueous solution of H<sub>2</sub>O<sub>2</sub>'''
|-
! H<sub>2</sub>O<sub>2</sub> (w/w) !! Density (g/cm<sup>3</sup>) !! Temperature (°C)
|-
| 3% || 1.0095 || 15
|-
| 27% || 1.10 || 20
|-
| 35% || 1.13 || 20
|-
| 50% || 1.20 || 20
|-
| 70% || 1.29 || 20
|-
| 75% || 1.33 || 20
|-
| 96% || 1.42 || 20
|-
| 98% || 1.43 || 20
|-
| 100% || 1.450 || 20
|}
==Uses==
===Structure===
===Industrial applications===
Hydrogen peroxide ({{chem|H|2|O|2}}), is a nonplanar molecule with (twisted) C<sub>2</sub> [[Molecular symmetry#Common point groups|symmetry]]. Although the O−O bond is a single bond, the molecule has a relatively high barrier to rotation of 2460 [[Wavenumber|cm<sup>−1</sup>]] (29.45 [[Kilojoule|kJ]]/[[Mole (chemistry)|mol]]);<ref>{{cite journal|last=Hunt|first=Robert H.|author2=Leacock, Robert A. |author3=Peters, C. Wilbur |author4= Hecht, Karl T. |title=Internal-Rotation in Hydrogen Peroxide: The Far-Infrared Spectrum and the Determination of the Hindering Potential|journal=The Journal of Chemical Physics|year=1965|volume=42|issue=6|page=1931|doi=10.1063/1.1696228|url=http://deepblue.lib.umich.edu/bitstream/handle/2027.42/71115/JCPSA6-42-6-1931-1.pdf?sequence=2|bibcode=1965JChPh..42.1931H}}</ref> for comparison, the rotational barrier for [[ethane]] is 12.5 kJ/mol. The increased barrier is ascribed to repulsion between the [[lone pair]]s of the adjacent oxygen atoms and results in hydrogen peroxide displaying [[atropisomer]]ism.
About 50% of the world's production of hydrogen peroxide in 1994 was used for pulp- and paper-bleaching. Other bleaching applications are becoming more important as hydrogen peroxide is seen as an environmentally benign alternative to [[chlorine]]-based bleaches.
The molecular structures of gaseous and [[crystalline]] {{chem|H|2|O|2}} are significantly different. This difference is attributed to the effects of [[hydrogen bonding]], which is absent in the gaseous state.<ref>{{Cite book|last=Dougherty|first=Dennis A.|author2=Eric V. Anslyn |title=Modern Physical Organic Chemistry |publisher=University Science |year=2005 |page=122|isbn=1-891389-31-9 }}</ref> Crystals of {{chem|H|2|O|2}} are [[tetragonal]] with the [[space group]] <math>D_4^4 P4_12_1</math>.<ref>{{cite journal|last=Abrahams|first=S. C.|author2=Collin, R. L. |author3=Lipscomb, W. N. |title=The crystal structure of hydrogen peroxide|journal=Acta Crystallographica|date=1 January 1951|volume=4|issue=1|pages=15–20|doi=10.1107/S0365110X51000039}}</ref>
Other major industrial applications for hydrogen peroxide include the manufacture of [[sodium percarbonate]] and [[sodium perborate]], used as mild bleaches in [[laundry]] [[detergent]]s. It is used in the production of certain [[organic peroxide]]s such as [[dibenzoyl peroxide]], used in [[Radical polymerization|polymerisation]]s and other chemical processes. Hydrogen peroxide is also used in the production of [[epoxide]]s such as [[propylene oxide]]. Reaction with [[carboxylic acid]]s produces a corresponding [[peroxy acid]]. [[Peracetic acid]] and [[meta-chloroperoxybenzoic acid]] (commonly abbreviated mCPBA) are prepared from [[acetic acid]] and ''meta''-chlorobenzoic acid, respectively. The latter is commonly reacted with [[alkene]]s to give the corresponding [[epoxide]].
{{multiple image
In PCB manufacturing process, hydrogen peroxide mixed with sulfuric acid was used as the microetch chemical for copper surface roughening preparation.
| direction = vertical
| align = left
| header =
| width = 250
| image1 = H2O2 gas structure.png
| alt1 = O-O bond length = 147.4 pm <br>O-H bond length = 95.0 pm
| caption1 = Structure and dimensions of H<sub>2</sub>O<sub>2</sub> in the gas phase
| image2 = H2O2 solid structure.png
| alt2 = O-O bond length = 145.8 pm <br>O-H bond length = 98.8 pm
| caption2 = Structure and dimensions of H<sub>2</sub>O<sub>2</sub> in the solid (crystalline) phase
}}
New industrial and home applications may be developed with the discovery of a catalytic reaction using powdered precious metal-based catalyst, hydrogen peroxide and methyl alcohol (see References). A small plastic bottle incorporating these can produce superheated steam in one to two seconds releasing only C02 and high temperature steam for a variety of purposes.
{| class="wikitable sortable" style="margin:1em auto 1em auto; width:380px;"
|+ Properties of H<sub>2</sub>O<sub>2</sub> and its analogues <br> <sub>values marked * are extrapolated</sub>
|-
! Name !! Formula !! [[Molar mass]] (g mol<sup>−1</sup>) !! Mpt (°C) !! Bpt (°C)
Hydrogen peroxide has several structural analogues with H<sub>m</sub>-E-E-H<sub>n</sub> bonding arrangements ([[Properties of water|Water]] also shown for comparison). It has the highest (theoretical) boiling point of this series (X = O, N, S). Its melting point is also fairly high, being comparable to that of [[hydrazine]] and water, with only [[hydroxylamine]] crystallising significantly more readily, indicative of particularly strong [[hydrogen bonding]]. [[Diphosphane]] and [[hydrogen disulfide]] exhibit only weak hydrogen bonding and have little chemical similarity to hydrogen peroxide. All of these analogues are thermodynamically unstable. Structurally, the analogues all adopt similar skewed structures, due to repulsion between adjacent [[lone pairs]].
* Diluted H<sub>2</sub>O<sub>2</sub> (around 3%) is used to bleach human [[hair]], hence the phrase "peroxide blonde". It is absorbed by skin upon contact and creates a local skin [[capillary]] [[embolism]] which appears as a temporary whitening of the skin. It is used to whiten bones that are to be put on display.
==Discovery==
* 3% H<sub>2</sub>O<sub>2</sub> is used medically for cleaning wounds, removing dead tissue, and as an oral [[debridement|debriding]] agent. Most over-the-counter peroxide solutions are not suitable for ingestion.
Hydrogen peroxide was first described in 1818 by [[Louis Jacques Thénard]], who produced it by treating [[barium peroxide]] with [[nitric acid]].<ref>{{Cite journal
* The [[Food and Drug Administration]] (FDA) has classified hydrogen peroxide as a Low Regulatory Priority (LRP) drug for use in controlling fungus on fish and fish eggs. (See [[ectoparasite]].)
| title = Observations sur des nouvelles combinaisons entre l’oxigène et divers acides
* Some gardeners and users of [[hydroponics]] advocate the use of hydrogen peroxide in watering solutions. They claim that its spontaneous decomposition releases oxygen that enhances a plant's root development and helps to treat [[root rot]] (cellular root death due to lack of oxygen).
| author = L. J. Thénard
* Laboratory tests conducted by fish culturists in recent years have demonstrated that common household hydrogen peroxide can be used safely to provide oxygen for small fish.<ref>[http://www.great-lakes.org/Wkly_news/07-07-03.html#Oxygen Great-lakes.org]</ref><ref>[http://www.fws.gov/midwest/ashland/mtan/mtan_35.html#Guide%20to%20Drug,%20Vaccine,%20and%20Pesticide%20Use%20in%20Aquaculture fws.gov]</ref> Hydrogen peroxide releases oxygen by decomposition when it is exposed to [[catalysts]] such as [[manganese dioxide]].
| journal = [[Annales de chimie et de physique]], 2nd series
* Hydrogen peroxide is a strong oxidizer effective in controlling sulfide and organic related odors in wastewater collection and treatment systems. It is typically applied to a wastewater system where there is a retention time of 30 minutes to 5 hours before hydrogen sulfide is released. Hydrogen peroxide oxidizes the hydrogen sulfide and promotes bio-oxidation of organic odors. Hydrogen peroxide decomposes to oxygen and water, adding dissolved oxygen to the system thereby negating some Biological Oxygen Demand (BOD).
| volume = 8
*Commercial peroxide, as bought at the drugstore in a 2.5%-3% solution, can be used to remove [[blood]][[stain]]s from fabrics, although it will bleach or discolor many fabrics. If a little peroxide is poured onto the stain it will bubble up in the area of the blood, due to a reaction with [[catalase]].[http://nicholasacademy.com/scienceexperiment213peroxidebubbles.html] After a few minutes the excess liquid can be wiped up with a cloth or paper towel and the stain will be gone.
| year =1818
* Hydrogen peroxide is used with [[phenyl oxalate ester]] and an appropriate [[dye]] in [[glow stick]]s as an [[oxidizing agent]]. It reacts with the ester to form an unstable CO<sub>2</sub> [[dimer]] which excites the dye to an [[excited state]]; the dye emits a [[photon]] (light) when it [[spontaneous emission|spontaneously relaxes]] back to the [[ground state]].
| pages = 306–312
| url = http://books.google.com/books?id=-N43AAAAMAAJ&pg=PA306#v=onepage&q&f=false}}</ref> An improved version of this process used [[hydrochloric acid]], followed by addition of [[sulfuric acid]] to precipitate the [[barium sulfate]] byproduct. Thénard's process was used from the end of the 19th century until the middle of the 20th century.<ref>C. W. Jones, J. H. Clark. ''Applications of Hydrogen Peroxide and Derivatives''. Royal Society of Chemistry, '''1999'''.</ref>
===Storage===
Pure hydrogen peroxide was long believed to be unstable as early attempts to separate it from the water, which is present during synthesis, all failed. This instability was due to traces of impurities ([[transition metals]] [[salt]]s) which catalyze the decomposition of the hydrogen peroxide. Pure hydrogen peroxide was first obtained in 1894 — almost 80 years after its discovery — by [[Richard Wolffenstein (chemist)|Richard Wolffenstein]], who produced it via [[vacuum distillation]].<ref>{{cite journal|last=Wolffenstein|first=Richard|title=Concentration und Destillation von Wasserstoffsuperoxyd|journal=Berichte der deutschen chemischen Gesellschaft|date=October 1894|volume=27|issue=3|pages=3307–3312|url=http://gallica.bnf.fr/ark:/12148/bpt6k90736r/f704.image.langEN|doi=10.1002/cber.189402703127|language=German}}</ref>
Regulations vary, but low concentrations, such as 2.5% are widely available and legal to buy for medical use. Small quantities of many different concentrations and grades can be legally stored and used with few regulations.
Hydrogen peroxide should be stored in a container made from a material that it doesn't react with and doesn't catalyze its decomposition. Numerous materials and processes are available, some stainless steels, many plastics, glasses and some aluminium alloys are compatible.<ref>[http://www.ozoneservices.com/articles/004.htm Ozonelab Peroxide compatibility]</ref>
Determination of the molecular structure of hydrogen peroxide proved to be very difficult. In 1892 the Italian physical chemist Giacomo Carrara (1864–1925) determined its molecular weight by freezing point depression, which confirmed that its molecular formula is H<sub>2</sub>O<sub>2</sub>.<ref>G. Carrara (1892) [http://books.google.com/books?id=Yk46AQAAMAAJ&pg=PA19#v=onepage&q&f=false "Sul peso molecolare e sul potere rifrangente dell' acqua ossigenata"] (On the molecular weight and on the refractive power of oxygenated water [i.e., hydrogen peroxide]), ''Atti della Reale Accademia dei Lincei'', series 5, '''1''' (2) : 19-24.<br>
Carrara's findings were confirmed by: W. R. Orndorff and John White (1893) [http://books.google.com/books?id=QKYwAAAAYAAJ&pg=PA347#v=onepage&q&f=false "The molecular weight of hydrogen peroxide and of benzoyl peroxide,"] ''American Chemical Journal'', '''15''' : 347-356.</ref> At least half a dozen hypothetical molecular structures seemed to be consistent with the available evidence.<ref>See, for example:
* In 1882, Kingzett proposed as a structure H<sub>2</sub>O=O. See: Charles Thomas Kingzett (29 September 1882) [http://books.google.com/books?id=1OYEAAAAQAAJ&pg=RA1-PA141#v=onepage&q&f=false "On the activity of oxygen and the mode of formation of hydrogen dioxide,"] ''The Chemical News'', '''46''' (1192) : 141-142.
* In his 1922 textbook, Joseph Mellor considered three hypothetical molecular structures for hydrogen peroxide, admitting (p. 952): " … the constitution of this compound has not been yet established by unequivocal experiments." See: Joseph William Mellor, ''A Comprehensive Treatise on Inorganic and Theoretical Chemistry'', vol. 1 (London, England: Longmans, Green and Co., 1922), [http://books.google.com/books?id=PnjVAAAAMAAJ&pg=PA952#v=onepage&q&f=false pages 952-956.]
* W. C. Schumb, C.N. Satterfield, and R.L. Wentworth (1 December 1953) [http://hydrogen-peroxide.us/chemical-properties/MIT-Schumb_etal-hydrogen_Peroxide_ch5_n_ch6-1954.pdf "Report no. 43: Hydrogen peroxide, Part two,"] Office of Naval Research, Contract No. N5ori-07819 On p. 178, the authors present six hypothetical models for hydrogen peroxide's molecular structure. On p. 184, the present structure is considered almost certainly correct — although a small doubt remained. (Note: The report by Schumb et al. was reprinted as: W.C. Schumb, C.N. Satterfield, and R.L. Wentworth, ''Hydrogen Peroxide'' (New York, New York: Reinhold Publishing Corp. (American Chemical Society Monograph), 1955).)</ref> In 1934, the English mathematical physicist [[William Penney, Baron Penney|William Penney]] and the Scottish physicist [[Gordon Sutherland]] proposed a molecular structure for hydrogen peroxide which was very similar to the presently accepted one.<ref>See:
* W.G. Penney and G.B.B.M. Sutherland (1934) "The theory of the structure of hydrogen peroxide and hydrazine," ''Journal of Chemical Physics'', '''2''' (8) : 492-498.
* W.G. Penney and G.B.B.M. Sutherland (1934) "A note on the structure of H<sub>2</sub>O<sub>2</sub> and H<sub>4</sub>N<sub>2</sub> with particular reference to electric moments and free rotation," ''Transactions of the Faraday Society'', '''30''' : 898-902.</ref>
Peroxide is a strong oxidant and should be stored away from fuel sources and sources of catalytic contamination (see [[#Decomposition|decomposition section]]). Apart from obvious fire risks, peroxide vapour can react with hydrocarbons and alcohols to form contact explosives. Because oxygen is formed during the natural decomposition of the peroxide, the resulting increase in pressure can cause a container (e.g. made of glass) to shatter. Peroxide should be kept cool, as peroxide vapour can detonate above 70 °C. Deaths have occurred from storage in inadequately labeled containers due to its apparent similarity to water.
==Manufacture==
Previously, hydrogen peroxide was prepared industrially by [[hydrolysis]] of the [[ammonium peroxydisulfate]], which was itself obtained via the [[electrolysis]] of a solution of [[ammonium bisulfate]] ({{chem|NH|4|HSO|4}}) in [[sulfuric acid]].
Today, hydrogen peroxide is manufactured almost exclusively by the [[anthraquinone process]], which was formalized in 1936 and patented in 1939. It begins with the reduction of an [[anthraquinone]] (such as [[2-ethylanthraquinone]] or the 2-amyl derivative) to the corresponding [[anthrahydroquinone]], typically via [[hydrogenation]] on a [[palladium]] [[catalyst]]; the anthrahydroquinone then undergoes to [[autoxidation]] to regenerate the starting anthraquinone, with hydrogen peroxide being produced as a by-product. Most commercial processes achieve oxidation by bubbling [[compressed air]] through a solution of the derivatized [[anthracene]], whereby the oxygen present in the air reacts with the labile hydrogen atoms (of the hydroxy group), giving hydrogen peroxide and regenerating the anthraquinone. Hydrogen peroxide is then [[Liquid-liquid extraction|extracted]] and the [[anthraquinone]] derivative is reduced back to the dihydroxy (anthracene) compound using [[hydrogen]] gas in the presence of a metal [[catalyst]]. The cycle then repeats itself.<ref name="Antra">{{Cite journal
H<sub>2</sub>O<sub>2</sub> can be used either as a [[monopropellant]] (not mixed with fuel) or as the oxidizer component of a [[bipropellant rocket]]. Use as a monopropellant takes advantage of the decomposition of 70–98+% concentration hydrogen peroxide into steam and oxygen. The propellant is pumped into a reaction chamber where a catalyst, usually a silver or platinum screen, triggers decomposition, producing steam at over 600 °C which is expelled through a [[nozzle]], generating [[thrust]]. H<sub>2</sub>O<sub>2</sub> monopropellant produces a maximum [[specific impulse]] (''I''<sub>sp</sub>) of 161 s (1.6 [[newton-second|kN·s]]/kg), which makes it a low-performance monopropellant. Peroxide generates much less thrust than [[toxic]] [[hydrazine]], but is not toxic. The [[Bell Rocket Belt]] used hydrogen peroxide monopropellant.
| title = Hydrogen Peroxide Synthesis: An Outlook beyond the Anthraquinone Process
| pages = 6962–6984
| author = Jose M. Campos-Martin, Gema Blanco-Brieva, Jose L. G. Fierro
| year = 2006
| doi =10.1002/anie.200503779
| journal = Angewandte Chemie International Edition
| volume = 45
| issue =42
| pmid = 17039551| last2 = Blanco-Brieva
| last3 = Fierro
}}</ref><ref name="Riedl&Pleiderer">H. Riedl and G. Pfleiderer, U.S. Patent 2,158,525 (2 October 1936 in USA, and 10 October 1935 in Germany) to I. G. Farbenindustrie, Germany</ref>
As a bipropellant H<sub>2</sub>O<sub>2</sub> is decomposed to burn a fuel as an oxidizer. Specific impulses as high as 350 s (3.5 kN·s/kg) can be achieved, depending on the fuel. Peroxide used as an oxidizer gives a somewhat lower ''I''<sub>sp</sub> than liquid oxygen, but is dense, storable, noncryogenic and can be more easily used to drive gas turbines to give high pressures. It can also be used for regenerative cooling of rocket engines. Peroxide was used very successfully as an oxidizer in World-War-II German rockets (e.g. [[T-Stoff]] for the [[Me-163]]), and for the low-cost British [[Black Knight (rocket)|Black Knight]] and [[Black Arrow]] launchers.
The simplified overall equation for the process is deceptively simple:<ref name="Antra"/>
:{{chem|H|2}} + {{chem|O|2}} → {{chem|H|2|O|2}}
In the 1940s and 1950s the [[Hellmuth Walter|Walter]] [[gas turbine|turbine]] used hydrogen peroxide for use in [[submarine]]s while submerged; it was found to be too noisy and require too much maintenance compared to [[diesel-electric]] power systems. Some [[torpedo]]es used hydrogen peroxide as oxidizer or propellant, but this was dangerous and has been discontinued by most [[navy|navies]]. Hydrogen peroxide leaks were blamed for the sinkings of [[HMS Sidon (P259)|HMS ''Sidon'']] and the [[Russian submarine Kursk|Russian submarine ''Kursk'']]. It was discovered, for example, by the Japanese Navy in torpedo trials, that the concentration of H<sub>2</sub>O<sub>2</sub> in right-angle bends in HTP pipework can often lead to explosions in submarines and torpedoes. Hydrogen peroxide is still used on [[Soyuz]] for driving gas turbines to power turbopumps, however. SAAB Underwater Systems is manufacturing the Torpedo 2000. This torpedo, used by the Swedish navy, is powered by a piston engine propelled by HTP as an oxidizer and [[kerosene]] as a fuel in a bipropellant system<ref>{{cite journal|last=Scott|first=Richard |date=November, [[1997]]|year=1997|title=Homing Instincts|journal=Jane's Navy International|url=http://babriet.tripod.com/articles/art_hominginstinct.htm}}</ref>.
The economics of the process depend heavily on effective recycling of the [[quinone]] (which is expensive) and extraction solvents, and of the [[hydrogenation]] [[catalyst]].
While rarely used now as a monopropellant for large engines, small hydrogen peroxide [[attitude control]] [[thruster]]s are still in use on some [[satellite]]s. They are easy to throttle, and safer to fuel and handle before launch than hydrazine thrusters. However, hydrazine is more often used in spacecraft because of its higher [[specific impulse]] and lower rate of decomposition.
A process to produce hydrogen peroxide directly from the elements has been of interest for many years. Direct synthesis is difficult to achieve as, in terms of thermodynamics, the reaction of hydrogen with oxygen favours production of water. Systems for direct synthesis have been developed; most of which are based around finely dispersed metal catalysts.<ref>Noritaka Mizuno Gabriele Centi, Siglinda Perathoner, Salvatore Abate "Direct Synthesis of Hydrogen Peroxide: Recent Advances" in ''Modern Heterogeneous Oxidation Catalysis: Design, Reactions and Characterization'' 2009, Wiley-VCH. {{DOI|10.1002/9783527627547.ch8}}</ref><ref name="Hutchings">{{cite journal|last=Edwards|first=J. K.|author2=Solsona, B. |author3=N, E. N. |author4=Carley, A. F. |author5=Herzing, A. A. |author6=Kiely, C. J. |author7= Hutchings, G. J. |title=Switching Off Hydrogen Peroxide Hydrogenation in the Direct Synthesis Process|journal=Science|date=20 February 2009|volume=323|issue=5917|pages=1037–1041|doi=10.1126/science.1168980|pmid=19229032|bibcode=2009Sci...323.1037E}}</ref> None of these has yet reached a point where they can be used for industrial-scale synthesis.
Recently H<sub>2</sub>O<sub>2</sub>/[[propylene]] has been proposed as an approach to inexpensive [[SSTO|Single Stage To Orbit]]: a fuel tank containing propylene has a bladder floating in it containing H<sub>2</sub>O<sub>2</sub>. This combination offers 15% superior ISP to O2/RP4 (a [[kerosene]] used as rocket propellant), does not need [[turbine]]s or [[cryogenic]] storage or hardware, and greatly reduces the cost of the booster. The potential of this and other alternative systems is discussed in some detail at [http://www.dunnspace.com/ Dunn Engineering].
===Availability===
Hydrogen peroxide is most commonly available as a solution in water. For consumers, it is usually available from pharmacies at 3 and 6 wt% concentrations. The concentrations are sometimes described in terms of the volume of oxygen gas generated; one milliliter of a 20-volume solution generates twenty milliliters of oxygen gas when completely decomposed. For laboratory use, 30 wt% solutions are most common. Commercial grades from 70% to 98% are also available, but due to the potential of solutions of more than 68% hydrogen peroxide to be converted entirely to steam and oxygen (with the temperature of the steam increasing as the concentration increases above 68%) these grades are potentially far more hazardous, and require special care in dedicated storage areas. Buyers must typically allow inspection by commercial manufacturers.
===Therapeutic use===
In 1994, world production of {{chem|H|2|O|2}} was around 1.9 million [[tonne]]s and grew to 2.2 million in 2006,<ref name=HageLienke/> most of which was at a concentration of 70% or less. In that year bulk 30% {{chem|H|2|O|2}} sold for around US $0.54 per [[Kilogram|kg]], equivalent to US $1.50 per kg (US $0.68 per [[pound (mass)|lb]]) on a "100% basis".<ref>[http://www.researchgate.net/publication/6755101_Hydrogen_peroxide_synthesis_an_outlook_beyond_the_anthraquinone_process/file/9c96051d53c4cebcc7.pdf&ei=RPH6Uc-8Ho7dsgaG34HABA&usg=AFQjCNHo39mqrJejAY9aylDK4TdWfV3FBg&sig2=nsf38AeKirAjpSrOKBTd-Q Hydrogen Peroxide Synthesis] researchgate</ref><ref>[http://www.dsir.gov.in/reports/techreps/tsr010.pdf research for Ministry of Science and Technology], Government of [[India]]</ref>
Hydrogen peroxide is ''[[generally recognized as safe]]'' (GRAS) as an [[antimicrobial agent]], an oxidizing agent and for other purposes by the US [[Food and Drug Administration]].<ref>{{cite web|title=Sec. 184.1366 Hydrogen peroxide|publisher=U.S. Government Printing Office via GPO Access|url=http://a257.g.akamaitech.net/7/257/2422/04nov20031500/edocket.access.gpo.gov/cfr_2001/aprqtr/21cfr184.1366.htm|date=[[2001-04-01]]|accessdate=2007-07-07}}</ref>
Hydrogen peroxide has been used as an [[antiseptic]] and anti-bacterial agent for many years due to its oxidizing effect. While its use has decreased in recent years with the popularity of better-smelling and more readily-available over the counter products, it is still used by many hospitals, doctors and dentists in sterilizing, cleaning and treating everything from floors to [[root canal]] procedures.
==Reactions==
* Hydrogen peroxide can be used as a toothpaste when mixed with correct quantities of baking soda and salt.<ref>{{cite web|last=Shepherd|first=Steven|publisher=FDA Consumer|title=Brushing Up on Gum Disease|url=http://www.fda.gov/bbs/topics/CONSUMER/CON00065.html|accessdate=2007-07-07}}</ref>
* Hydrogen peroxide and [[benzoyl peroxide]] are sometimes used to treat [[Acne vulgaris|acne]].<ref>{{cite journal|last=Milani|first=Massimo|coauthors=Bigardi, Andrea; Zavattarelli, Marco|year=2003|title=Efficacy and safety of stabilised hydrogen peroxide cream (Crystacide) in mild-to-moderate acne vulgaris: a randomised, controlled trial versus benzoyl peroxide gel|url=http://www.ingentaconnect.com/content/libra/cmro/2003/00000019/00000002/art00010|journal=Current Medical Research and Opinion|issn=|volume=19|issue=2|pages=135-138(4)|doi=10.1185/030079902125001523}}</ref>
* Hydrogen peroxide is used as an [[emetic]] in veterinary practice.<ref>{{cite encyclopedia|title=Drugs to Control or Stimulate Vomiting|encyclopedia=Merck Veterinary manual|url=http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/190303.htm|publisher=[[Merck & Co.]], Inc|date=2006}}</ref>
;"Alternative" uses
===Decomposition===
* Some people have tried using peroxide as a treatment for cancer, often then dying of a cancer which could have been treated effectively by modern medicine. The [[American Cancer Society]] states that "there is no scientific evidence that hydrogen peroxide is a safe, effective or useful cancer treatment", and advises cancer patients to "remain in the care of qualified doctors who use proven methods of treatment and approved clinical trials of promising new treatments." <ref>{{cite journal|title=Questionable methods of cancer management: hydrogen peroxide and other 'hyperoxygenation' therapies |journal=CA: a cancer journal for clinicians|volume=43|issue=1|pages=47-56|year=1993|pmid=8422605}}</ref>
Hydrogen peroxide is [[thermodynamic]]ally unstable and decomposes to form water and oxygen with a [[Standard enthalpy change of reaction|Δ''H''<sup><s>o</s></sup>]] of −98.2 [[Kilojoule|kJ]]·[[Mole (chemistry)|mol]]<sup>−1</sup> and a Δ[[Entropy|S]] of 70.5 J·mol<sup>−1</sup>·K<sup>−1</sup>.
* Another controversial alternative medical procedure is [[inhalation]] of hydrogen peroxide at a concentration of about 1%. Internal use of hydrogen peroxide has a history of causing [[fatal]] [[blood disorder]]s, and its recent use as a therapeutic treatment has been linked to several [[death]]s.<ref>{{cite news|last=Cooper|first=Anderson|title=A Prescription for Death?|publisher=CBS News|date=[[2005-01-12]]|url=http://www.cbsnews.com/stories/2005/01/12/60II/main666489.shtml|accessdate=2007-07-07}}</ref><ref>{{cite web|last=Mikkelson|first=Barbara|title=Hydrogen Peroxide|url=http://www.snopes.com/medical/healthyself/peroxide.asp|publisher=Snopes.com|date=[[2006-04-30]]|accessdate=2007-07-07}}</ref>
[[Image:H2O2 structure.png|500px|Structure of hydrogen peroxide]]
While the [[Linear alkane conformation|anti conformer]] would minimize steric repulsions, a 90° torsion angle would optimize mixing between the filled ''p-type'' orbital of the oxygen (one of the lone pairs) and the [[LUMO]] of the [[vicinal]] O-H bond.<ref>{{cite book|last=Dougherty|first=Dennis A.|coauthors=Eric V. Anslyn |title=Modern Physical Organic Chemistry |publisher=University Science |location= |year=2005 |pages=122|isbn=1-891389-31-9 |oclc= |doi=}}</ref> Reflecting a compromise between the two interactions, gaseous and liquid hydrogen peroxide adopts an [[Linear alkane conformation|anticlinal]] "skewed" shape. This [[rotational conformation]] is a compromise between the ''anti'' conformer, which would minimze steric repulsion, and between the [[lone pair]]s on the oxygen atoms. Despite the fact that the O-O bond is a single bond, the molecule has a remarkably high barrier to complete rotation of 29.45 [[Kilojoule|kJ]]/[[Mole (chemistry)|mol]] (compared with 12.5 kJ/mol for the rotational barrier of [[ethane]]). The increased barrier is also attributed to lone-pair lone-pair repulsion. The [[Molecular geometry|bond angle]]s are affected by [[hydrogen bonding]], which is relevant to the structural difference between gaseous and crystalline forms; indeed a wide range of values is seen in crystals containing molecular H<sub>2</sub>O<sub>2</sub>.
The rate of decomposition increases with rising temperature, concentration and [[pH]], with cool, dilute, acidic solutions showing the best stability. Decomposition is [[catalyse]]d by various compounds, including most [[transition metal]]s and their compounds (e.g. [[manganese dioxide]], [[silver]], and [[platinum]]).<ref>{{cite book|title=General Chemistry: Principles & Modern Applications|author = Petrucci, Ralph H.|edition=9th|page = 606|publisher = Prentice Hall|year = 2007|isbn=0-13-149330-2}}</ref> Certain metal ions, such as {{chem|link=ferrous|Fe|2+}} or {{chem|link=titanium(III) chloride|Ti|3+}}, can cause the decomposition to take a different path, with [[free radical]]s such as ([[Hydroxyl radical|HO·]]) and ([[hydroperoxyl|HOO·]]) being formed.
== Chemical properties ==
Non-metallic catalysts include [[potassium iodide]], which reacts particularly rapidly and forms the basis of the [[elephant toothpaste]] experiment. Hydrogen peroxide can also be decomposed biologically by [[enzyme]] [[catalase]].
H<sub>2</sub>O<sub>2</sub> is one of the most powerful oxidizers known -- stronger than [[chlorine]], [[chlorine dioxide]], and [[potassium permanganate]]. And through catalysis, H<sub>2</sub>O<sub>2</sub> can be converted into hydroxyl radicals (.OH) with reactivity second only to fluorine.
The decomposition of hydrogen peroxide liberates oxygen and heat; this can be dangerous as spilling high concentrations of hydrogen peroxide on a flammable substance can cause an immediate fire.
===Redox reactions===
Hydrogen peroxide exhibits oxidizing and reducing properties, depending on pH.
In acidic solutions, {{chem|H|2|O|2}} is one of the most powerful oxidizers known—stronger than [[chlorine]], [[chlorine dioxide]], and [[potassium permanganate]]. Also, through catalysis, {{chem|H|2|O|2}} can be converted into [[hydroxyl radical]]s (<sup>•</sup>OH), which are highly reactive.
{| class="wikitable"
{| class="wikitable"
! [[Oxidant]]
|-
! [[Oxidant]]/Reduced product
! [[Oxidation]] potential, V
! [[Oxidation]] potential, V
|-
|-
| [[Fluorine]]
| [[Fluorine]]/Hydrogen fluoride
| 3.0
| 3.0
|-
|-
| [[Hydroxyl]] radical
| [[Ozone]]/Oxygen
| 2.8
|-
| [[Ozone]]
| 2.1
| 2.1
|-
|-
| Hydrogen peroxide
| Hydrogen peroxide/Water
| 1.8
| 1.8
|-
|-
| [[Potassium permanganate]]
| [[Potassium permanganate]]/Manganese dioxide
| 1.7
| 1.7
|-
|-
| [[Chlorine dioxide]]
| [[Chlorine dioxide]]/HClO
| 1.5
| 1.5
|-
|-
| [[Chlorine]]
| [[Chlorine]]/Chloride
| 1.4
| 1.4
|-
|}
|}
Hydrogen peroxide can decompose spontaneously into water and oxygen. It usually acts as an [[Redox|oxidizing agent]], but there are many reactions where it acts as a [[Redox|reducing agent]], releasing oxygen as a by-product.
In [[acid]]ic solutions {{chem|Fe|2+}} is oxidized to {{chem|Fe|3+}} (hydrogen peroxide acting as an oxidizing agent),
It also readily forms both inorganic and organic [[peroxide]]s.
and [[sulfite]] ({{chem|SO|3|2−}}) is oxidized to [[sulfate]] ({{chem|SO|4|2−}}). However, [[potassium permanganate]] is reduced to {{chem|Mn|2+}} by acidic {{chem|H|2|O|2}}. Under [[alkaline]] conditions, however, some of these reactions reverse; for example, {{chem|Mn|2+}} is oxidized to {{chem|Mn|4+}} (as {{chem|link=Manganese(IV) oxide|MnO|2}}).
Hydrogen peroxide always decomposes (disproportionates) [[exothermic reaction|exothermically]] into [[water (molecule)|water]] and [[oxygen]] gas [[Spontaneous process|spontaneously]]:
In basic solution, hydrogen peroxide can reduce a variety of inorganic ions. When it acts as a reducing agent, [[oxygen]] gas is also produced. For example hydrogen peroxide will reduce [[sodium hypochlorite]] and [[potassium permanganate]], which is a convenient method for preparing [[oxygen]] in the laboratory.
This process is very favorable; it has a [[Standard enthalpy change of reaction|Δ''H''<sup><s>o</s></sup>]] of −98.2 [[Kilojoule|kJ]]·[[Mole (chemistry)|mol]]<sup>−1</sup> and a [[Gibbs free energy|Δ''G''<sup><s>o</s></sup>]] of −119.2 kJ·mol<sup>−1</sup> and a ΔS of 70.5 J·mol<sup>−1</sup>·K<sup>−1</sup>. The rate of decomposition is dependent on the temperature and concentration of the peroxide, as well as the [[pH]] and the presence of impurities and stabilizers. Hydrogen peroxide is incompatible with many substances that [[catalyse]] its decomposition, including most of the [[transition metal]]s and their compounds. Common catalysts include [[manganese dioxide]], and [[silver]]. The same reaction is catalysed by the [[enzyme]] [[catalase]], found in the [[liver]], whose main function in the body is the removal of toxic byproducts of [[metabolism]] and the reduction of [[oxidative stress]]. The decomposition occurs more rapidly in [[alkali]], so [[acid]] is often added as a stabilizer.
===Organic reactions===
Hydrogen peroxide is frequently used as an [[Redox|oxidizing agent]]. Illustrative is oxidation of [[thioether]]s to [[sulfoxide]]s.<ref>{{cite journal | last1 = Ravikumar | first1 = Kabayadi S. | last2 = Kesavan | first2 = Venkitasamy | last3 = Crousse | first3 = Benoit | last4 = Bonnet-Delpon | first4 = Danièle | last5 = Bégué | first5 = Jean-Pierre | year = 2003 | title = Mild and Selective Oxidation of Sulfur Compounds in Trifluoroethanol: Diphenyldisulfide and Methyl phenyl Sulfoxide | url = | journal = Org. Synth | volume = 80 | issue = | page = 184 | doi = 10.15227/orgsyn.080.0184 }}</ref><ref>{{cite doi |10.1055/s-2004-44387}}</ref>
The liberation of oxygen and energy in the decomposition has dangerous side effects. Spilling high concentration peroxide on a flammable substance can cause an immediate fire, which is further fueled by the oxygen released by the decomposing hydrogen peroxide. High-strength peroxide (also called high-test peroxide, or HTP) must be stored in a suitable, vented container to prevent the buildup of oxygen gas, which would otherwise lead to the eventual rupture of the container.
Alkaline hydrogen peroxide is used for [[epoxidation]] of electron-deficient alkenes such as [[acrylic acid]] derivatives, and for the oxidation of [[alkylborane]]s to [[alcohol]]s, the second step of [[hydroboration-oxidation]]. It is also the principal reagent in the [[Dakin oxidation]] process.
In the presence of certain catalysts, such as Fe<sup>2+</sup> or Ti<sup>3+</sup>, the decomposition may take a different path, with free radicals such as HO· ([[hydroxyl]]) and HOO· being formed. A combination of H<sub>2</sub>O<sub>2</sub> and Fe<sup>2+</sup> is known as [[Fenton's reagent]].
===Precursor to other peroxide compounds===
Hydrogen peroxide is a weak acid, forming [[hydroperoxide]] or [[peroxide]] [[salt]]s with many metals.
A common concentration for hydrogen peroxide is "20 volume", which means that when 1 volume of hydrogen peroxide is decomposed, it produces 20 volumes of oxygen. This is equivalent to about 6% or 1.7[[Molar solution|M]].
It also converts metal oxides into the corresponding peroxides. For example, upon treatment with hydrogen peroxide, [[chromic acid]] ({{chem|CrO|3}}) form an unstable blue peroxide CrO({{chem|O|2}}{{chem|)|2}}.
Hydrogen peroxide available at drug stores is three percent solution. In such small concentrations, it is less stable, and decomposes faster. It is usually stabilized with [[acetanilide]], a substance that has toxic side effects in significant amounts.
This kind of reaction is used industrially to produce peroxoanions. For example, reaction with [[borax]] leads to [[sodium perborate]], a bleach used in laundry detergents:
{{chem|H|2|O|2}} converts [[carboxylic acid]]s (RCO<sub>2</sub>H) into peroxy acids (RC(O)O<sub>2</sub>H), which are themselves used as oxidizing agents. Hydrogen peroxide reacts with [[acetone]] to form [[acetone peroxide]], and it interacts with [[ozone]] to form [[hydrogen trioxide]], also known as [[trioxidane]]. Reaction with [[urea]] produces the [[adduct]] [[hydrogen peroxide - urea]], used for whitening teeth. An acid-base adduct with [[triphenylphosphine oxide]] is a useful "carrier" for {{chem|H|2|O|2}} in some reactions.
In aqueous solution, hydrogen peroxide can oxidize or reduce a variety of inorganic ions. When it acts as a reducing agent, [[oxygen]] gas is also produced. In [[acid]] solution Fe<sup>2+</sup> is oxidized to Fe<sup>3+</sup>,
Hydrogen peroxide is also one of the two chief chemicals in the defense system of the [[bombardier beetle]], reacting with [[hydroquinone]] to discourage predators.
and [[sulfite]] (SO<sub>3</sub><sup>2−</sup>) is oxidized to [[sulfate]] (SO<sub>4</sub><sup>2−</sup>). However, [[potassium permanganate]] is reduced to Mn<sup>2+</sup> by acidic H<sub>2</sub>O<sub>2</sub>. Under [[alkaline]] conditions, however, some of these reactions reverse; for example, Mn<sup>2+</sup> is oxidized to Mn<sup>4+</sup> (as [[Manganese(IV) oxide|MnO<sub>2</sub>]]).
A study published in ''[[Nature (journal)|Nature]]'' found that hydrogen peroxide plays a role in the [[immune system]]. Scientists found that hydrogen peroxide presence inside cells increased after tissues are damaged in [[zebra fish]], which is thought to act as a signal to [[white blood cell]]s to converge on the site and initiate the healing process. When the genes required to produce hydrogen peroxide were disabled, white blood cells did not accumulate at the site of damage. The experiments were conducted on fish; however, because fish are genetically similar to humans, the same process is speculated to occur in humans. The study in ''Nature'' suggested [[asthma]] sufferers have higher levels of hydrogen peroxide in their lungs than healthy people, which could explain why asthma sufferers have inappropriate levels of white blood cells in their lungs.<ref name="BBC">{{Cite news|url=http://news.bbc.co.uk/1/hi/health/8078525.stm|title=Natural bleach 'key to healing' |date=6 June 2009|publisher=BBC News|accessdate=2 July 2009}}</ref><ref name="Nature zebra">{{Cite journal|accessdate=2 July 2009|last=Niethammer|first=Philipp|author2=Clemens Grabher, A. Thomas Look & Timothy J. Mitchison|date=3 June 2009|title=A tissue-scale gradient of hydrogen peroxide mediates rapid wound detection in zebrafish|journal=Nature|volume=459|pages= 996–9 |url=http://www.nature.com/nature/journal/v459/n7249/full/nature08119.html|doi=10.1038/nature08119|pmid=19494811|issue=7249|pmc=2803098|bibcode=2009Natur.459..996N|last3=Look|first3=A. Thomas|last4=Mitchison|first4=Timothy J.}}</ref>
Another example of hydrogen peroxide acting as a reducing agent is the reaction with [[Sodium hypochlorite]], this is a convenient method for preparing [[oxygen]] in the laboratory.
Hydrogen peroxide has important roles as a signaling molecule in the regulation of a wide variety of biological processes.<ref>{{cite journal |author=Veal EA, Day AM, Morgan BA |title=Hydrogen peroxide sensing and signaling |journal=Mol. Cell |volume=26 |issue=1 |pages=1–14 |date=April 2007 |pmid=17434122 |doi=10.1016/j.molcel.2007.03.016 |url=http://linkinghub.elsevier.com/retrieve/pii/S1097-2765(07)00186-4|last2=Day |last3=Morgan }}</ref> The compound is a major factor implicated in the [[free-radical theory of aging]], based on how readily hydrogen peroxide can decompose into a [[hydroxyl radical]] and how [[superoxide radical]] byproducts of [[cellular respiration|cellular metabolism]] can react with ambient water to form hydrogen peroxide.<ref>{{cite journal|last=Weindruch|first=Richard|title=Calorie Restriction and Aging|journal=Scientific American|date=January 1996|pages=49–52}}</ref> These hydroxyl radicals in turn readily react with and damage vital cellular components, especially those of the [[mitochondria]].<ref>{{cite journal |author=Giorgio M, Trinei M, Migliaccio E, Pelicci PG |title=Hydrogen peroxide: a metabolic by-product or a common mediator of ageing signals? |journal=Nat. Rev. Mol. Cell Biol. |volume=8 |issue=9 |pages=722–8 |date=September 2007 |pmid=17700625 |doi=10.1038/nrm2240 |last2=Trinei |last3=Migliaccio |last4=Pelicci }}</ref> At least one study has also tried to link hydrogen peroxide production to cancer.<ref>{{cite journal |author=López-Lázaro M |title=Dual role of hydrogen peroxide in cancer: possible relevance to cancer chemoprevention and therapy |journal=Cancer Lett. |volume=252 |issue=1 |pages=1–8 |date=July 2007 |pmid=17150302 |doi=10.1016/j.canlet.2006.10.029 |url=http://linkinghub.elsevier.com/retrieve/pii/S0304-3835(06)00592-1}}</ref> These studies have frequently been quoted in fraudulent treatment claims.{{citation needed|date=September 2014}}
The amount of hydrogen peroxide in biological systems can be assayed using a fluorimetric [[assay]].<ref name="pmid8074285">{{Cite journal | last1 = Rapoport | first1 = R. | last2 = Hanukoglu | first2 = I. | last3 = Sklan | first3 = D. | title = A fluorimetric assay for hydrogen peroxide, suitable for NAD(P)H-dependent superoxide generating redox systems. | journal = Anal Biochem | volume = 218 | issue = 2 | pages = 309–13 |date=May 1994 | doi = 10.1006/abio.1994.1183 | pmid = 8074285 }}</ref>
Hydrogen peroxide is frequently used as an [[Redox|oxidizing agent]] in organic chemistry. One application is for the oxidation of [[thioether]]s to [[sulfoxide]]s. For example, [[methyl]] [[phenyl]] sulfide was oxidised to methyl phenyl sulfoxide in 99% yield in methanol in 18 hours (or 20 minutes using a [[Titanium(III) chloride|TiCl<sub>3</sub>]] catalyst):
About 60% of the world's production of hydrogen peroxide is used for [[bleaching of wood pulp|pulp- and paper-bleaching]].<ref name=HageLienke>{{Cite journal| journal = Angewandte Chemie International Edition | title = Applications of Transition-Metal Catalysts to Textile and Wood-Pulp Bleaching | author = Ronald Hage, Achim Lienke | volume = 45 | issue = 2 | year = 2005 | doi = 10.1002/anie.200500525 | pages = 206–222 | pmid = 16342123| last2 = Lienke }}</ref>
The second major industrial application is the manufacture of [[sodium percarbonate]] and [[sodium perborate]] which are used as mild bleaches in [[laundry]] [[detergents]].
Alkaline hydrogen peroxide is used for [[epoxidation]] of electron-deficient alkenes such as [[acrylic acid]]s, and also for oxidation of [[alkylborane]]s to [[alcohol]]s, the second step of [[hydroboration-oxidation]].
It is used in the production of various [[organic peroxides]] with [[dibenzoyl peroxide]] being a high volume example. This is used in [[Radical polymerization|polymerisations]], as a [[flour bleaching agent]] and as a treatment for acne. [[Peroxy acid]]s, such as [[peracetic acid]] and [[meta-chloroperoxybenzoic acid]] are also typically produced using hydrogen peroxide.
=== Formation of peroxide compounds ===
Hydrogen peroxide is used in certain waste-water treatment processes to remove organic impurities. This is achieved by [[advanced oxidation process]]es, such as the [[Fenton reaction]],<ref>{{cite book|last=Tarr|first=edited by Matthew A.|title=Chemical degradation methods for wastes and pollutants environmental and industrial applications.|date=2003|publisher=M. Dekker|location=New York|isbn=9780203912553|page=165}}</ref><ref>{{cite journal|last1=Pignatello|first1=Joseph J.|last2=Oliveros|first2=Esther|last3=MacKay|first3=Allison|title=Advanced Oxidation Processes for Organic Contaminant Destruction Based on the Fenton Reaction and Related Chemistry|journal=Critical Reviews in Environmental Science and Technology|date=January 2006|volume=36|issue=1|pages=1–84|doi=10.1080/10643380500326564}}</ref> which use it to generate highly reactive [[hydroxyl radicals]] (·OH). These are able to destroy organic contaminates which are ordinarily difficult to remove, such as [[Aromatic hydrocarbon|aromatic]] or [[halogenated compound]]s.<ref>{{cite journal|last1=Pera-Titus|first1=Marc|last2=Garcı́a-Molina|first2=Verónica|last3=Baños|first3=Miguel A|last4=Giménez|first4=Jaime|last5=Esplugas|first5=Santiago|title=Degradation of chlorophenols by means of advanced oxidation processes: a general review|journal=Applied Catalysis B: Environmental|date=February 2004|volume=47|issue=4|pages=219–256|doi=10.1016/j.apcatb.2003.09.010}}</ref> It can also oxidize [[sulphur]] based compounds present in the waste; which is beneficial as it generally reduces their odour.<ref>{{cite encyclopedia | author = Goor, G.; Glenneberg, J.; Jacobi, S. | title = Ullmann's Encyclopedia of Industrial Chemistry | encyclopedia = Ullmann's Encyclopedia of Industrial Chemistry | year = 2007 | publisher = Wiley-VCH | location = Weinheim | doi = 10.1002/14356007.a13_443.pub2 | chapter = Hydrogen Peroxide | isbn = 3527306730 }}</ref>
Hydrogen peroxide is a weak acid, and it can form [[hydroperoxide]] or [[peroxide]] [[salt]]s or derivatives of many metals.
For example, on addition to an aqueous solution of [[chromic acid]] (CrO<sub>3</sub>) or acidic solutions of dichromate salts, it will form an unstable blue peroxide CrO(O<sub>2</sub>)<sub>2</sub>. In aqueous solution it rapidly decomposes to form oxygen gas and chromium salts.
===Medical===
It can also produce peroxoanions by reaction with [[anion]]s; for example, reaction with [[borax]] leads to [[sodium perborate]], a bleach used in laundry detergents:
====Disinfectant====
Hydrogen peroxide can be used for the sterilization of various surfaces,<ref name=ascenzi>{{cite book|last1=Ascenzi|first1=edited by Joseph M.|title=Handbook of disinfectants and antiseptics|date=1996|publisher=M. Dekker|location=New York|isbn=0824795245|page=161}}</ref> including surgical tools<ref>{{cite journal|last1=Rutala|first1=W. A.|last2=Weber|first2=D. J.|title=Disinfection and Sterilization in Health Care Facilities: What Clinicians Need to Know|journal=Clinical Infectious Diseases|date=1 September 2004|volume=39|issue=5|pages=702–709|doi=10.1086/423182|pmid=15356786}}</ref> and may be deployed as a vapor ([[Vaporized hydrogen peroxide|VHP]]) for room sterilization.<ref>{{cite journal|last1=Falagas|first1=M.E.|last2=Thomaidis|first2=P.C.|last3=Kotsantis|first3=I.K.|last4=Sgouros|first4=K.|last5=Samonis|first5=G.|last6=Karageorgopoulos|first6=D.E.|title=Airborne hydrogen peroxide for disinfection of the hospital environment and infection control: a systematic review|journal=Journal of Hospital Infection|date=July 2011|volume=78|issue=3|pages=171–177|doi=10.1016/j.jhin.2010.12.006|pmid=21392848}}</ref> H<sub>2</sub>O<sub>2</sub> demonstrates broad-spectrum efficacy against viruses, bacteria, yeasts, and bacterial spores.<ref>{{cite book|last1=Block|first1=[edited by] Seymour S.|title=Disinfection, sterilization, and preservation|date=2000|publisher=Lea & Febiger|location=Philadelphia|isbn=0683307401|pages=185–204|edition=5th|chapter=Chapter 9: Peroxygen compounds}}</ref> In general, greater activity is seen against [[gram-positive]] than [[gram-negative]] bacteria; however, the presence of [[catalase]] or other [[peroxidase]]s in these organisms can increase tolerance in the presence of lower concentrations.<ref>{{cite journal|last1=McDonnell|first1=G|last2=Russell|first2=AD|title=Antiseptics and disinfectants: activity, action, and resistance.|journal=Clinical Microbiology Reviews|date=January 1999|volume=12|issue=1|pages=147–79|pmid=9880479|pmc=88911}}</ref> Higher concentrations of H<sub>2</sub>O<sub>2</sub> (10 to 30%) and longer contact times are required for sporicidal activity.<ref>{{cite book|last1=Block|first1=[edited by] Seymour S.|title=Disinfection, sterilization, and preservation|date=2000|publisher=Lea & Febiger|location=Philadelphia|isbn=0683307401|pages=529–543|edition=5th|chapter=Chapter 27: Chemical Sporicidal and Sporostatic Agents}}</ref>
Hydrogen peroxide is seen as an environmentally safe alternative to [[chlorine]]-based bleaches, as it degrades to form oxygen and water and it is [[generally recognized as safe]] as an [[antimicrobial agent]] by the U.S. [[Food and Drug Administration]] (FDA).<ref>{{cite web|title=Sec. 184.1366 Hydrogen peroxide|publisher=U.S. Government Printing Office via GPO Access|url=http://a257.g.akamaitech.net/7/257/2422/04nov20031500/edocket.access.gpo.gov/cfr_2001/aprqtr/21cfr184.1366.htm|date=1 April 2001|accessdate=7 July 2007}}</ref>
H<sub>2</sub>O<sub>2</sub> converts [[carboxylic acid]]s (RCOOH) into peroxy acids (RCOOOH), which are themselves used as oxidizing agents. Hydrogen peroxide reacts with [[acetone]] to form [[acetone peroxide]], and it interacts with [[ozone]] to form [[hydrogen trioxide]]. Reaction with [[urea]] produces [[carbamide peroxide]], used for whitening teeth. An acid-base adduct with [[triphenylphosphine oxide]] is a useful "carrier" for H<sub>2</sub>O<sub>2</sub> in some reactions.
Historically hydrogen peroxide was used for disinfecting wounds, partly because of its low cost and prompt availability compared to other antiseptics. It is now thought to slow healing and lead to [[scar]]ring because it destroys newly formed [[Skin|skin cells]].<ref>{{cite journal |author=Wilgus TA, Bergdall VK, Dipietro LA, Oberyszyn TM |title=Hydrogen peroxide disrupts scarless fetal wound repair |journal=Wound Repair Regen |volume=13 |issue=5 |pages=513–9 |year=2005 |pmid=16176460 |doi=10.1111/j.1067-1927.2005.00072.x |url=http://www.ncbi.nlm.nih.gov/pubmed/16176460|last2=Bergdall |last3=Dipietro |last4=Oberyszyn }}</ref> Only a very low concentration of H<sub>2</sub>O<sub>2</sub> can induce healing, and only if not repeatedly applied.<ref>{{cite journal|last=Loo|first=Alvin Eng Kiat|author2=Wong, Yee Ting |author3=Ho, Rongjian |author4=Wasser, Martin |author5=Du, Tiehua |author6=Ng, Wee Thong |author7=Halliwell, Barry |author8= Sastre, Juan |title=Effects of Hydrogen Peroxide on Wound Healing in Mice in Relation to Oxidative Damage|journal=PLoS ONE|date=13 November 2012|volume=7|issue=11|pages=e49215|doi=10.1371/journal.pone.0049215|pmid=23152875|bibcode=2012PLoSO...749215L}}</ref> Surgical use can lead to [[gas embolism]] formation.<ref name="ReferenceA">{{cite journal | last1 = Shaw | first1 = A | last2 = Cooperman | first2 = A | last3 = Fusco | first3 = J | year = 1967 | title = Gas embolism produced by hydrogen peroxide | url = | journal = N Engl J Med | volume = 277 | issue = 5| pages = 238–41 | doi=10.1056/nejm196708032770504| pmid = 6029311 }}</ref> Despite this it is still used for wound treatment in many developing countries.<ref>{{cite journal|last1=Rahman|first1=GA|last2=Adigun|first2=IA|last3=Yusuf|first3=IF|last4=Ofoegbu|first4=CKP|title=Wound dressing where there is limitation of choice|journal=Nigerian Journal of Surgical Research|date=28 May 2010|volume=8|issue=3–4|doi=10.4314/njsr.v8i3-4.54882}}</ref><ref>{{cite journal|last1=Velding|first1=K.|last2=Klis|first2=S.-A.|last3=Abass|first3=K. M.|last4=Tuah|first4=W.|last5=Stienstra|first5=Y.|last6=van der Werf|first6=T.|title=Wound Care in Buruli Ulcer Disease in Ghana and Benin|journal=American Journal of Tropical Medicine and Hygiene|date=9 June 2014|volume=91|issue=2|pages=313–318|doi=10.4269/ajtmh.13-0255|pmid=24914002}}</ref>
Hydrogen peroxide reacts with [[ozone]] to form [[trioxidane]].
It is absorbed by [[skin]] upon contact and creates a local [[capillary]] [[embolism]] that appears as a temporary whitening of the skin.<ref>[http://www.hpa.org.uk/webc/hpawebfile/hpaweb_c/1246260031509 Toxicology of Hydrogen Peroxide, p.4]</ref>
=== Alkalinity ===
====Cosmetic applications====
Hydrogen peroxide is a much weaker [[Base (chemistry)|base]] than water, but it can still form adducts with very strong acids. The [[superacid]] [[Fluoroantimonic acid|HF/SbF<sub>5</sub>]] forms unstable compounds containing the [H<sub>3</sub>O<sub>2</sub>]<sup>+</sup> ion.
Diluted {{chem|H|2|O|2}} (between 1.9% and 12%) mixed with [[ammonium hydroxide]] is used to bleach human [[hair]]. The chemical's bleaching property lends its name to the phrase "[[peroxide blonde]]".<ref>{{cite book|last=Lane|first=Nick|title=Oxygen : the molecule that made the world|year=2003|publisher=Oxford University Press|location=Oxford|isbn=0198607830|page=117|url=http://books.google.com/?id=ziVk6CI82WgC&pg=PA117&dq=peroxide+blond#v=onepage&q=peroxide%20blond&f=false|edition=First issued in paperback, repr.}}</ref>
Hydrogen peroxide is also used for [[tooth whitening]] and can be mixed with baking soda and salt to make a home-made toothpaste.<ref>{{cite web|last=Shepherd|first=Steven|publisher=FDA Consumer|title=Brushing Up on Gum Disease|url=http://www.fda.gov/bbs/topics/CONSUMER/CON00065.html|accessdate=7 July 2007 |archiveurl = http://web.archive.org/web/20070514102017/http://www.fda.gov/bbs/topics/CONSUMER/CON00065.html |archivedate = 14 May 2007}}</ref>
== Manufacture ==
Hydrogen peroxide may be used to treat [[Acne vulgaris|acne]],<ref>{{cite journal|last=Capizzi|first=R.|author2=Landi, F. |author3=Milani, M. |author4= Amerio, P. |title=Skin tolerability and efficacy of combination therapy with hydrogen peroxide stabilized cream and adapalene gel in comparison with benzoyl peroxide cream and adapalene gel in common acne. A randomized, investigator-masked, controlled trial|journal=British Journal of Dermatology|volume=151|issue=2|pages=481–484|doi=10.1111/j.1365-2133.2004.06067.x|pmid=15327558|year=2004}}</ref> although [[benzoyl peroxide]] is a more common treatment.
Hydrogen peroxide is manufactured today almost exclusively by the [[autoxidation]] of 2-ethyl-9,10-dihydroxyanthracene to 2-ethylanthraquinone and hydrogen peroxide using oxygen from the air. The [[anthraquinone]] derivative is then [[Liquid-liquid extraction|extracted]] out and reduced back to the dihydroxy compound using [[hydrogen]] gas in the presence of a metal [[catalyst]]. The overall equation for the process is deceptively simple:
However the economics of the process depend on effective recycling of the quinone and extraction solvents, and of the [[hydrogenation]] [[catalyst]].
Practitioners of [[alternative medicine]] have advocated the use of hydrogen peroxide for the treatment of various conditions, including [[emphysema]], [[influenza]], [[AIDS]] and in particular [[cancer]].<ref>{{cite book|last=Douglass|first=William Campbell|title=Hydrogen peroxide : medical miracle|date=1995|publisher=Second Opinion Pub.|location=[Atlanta, GA]|isbn=9781885236074}}</ref> The practise calls for the daily consumption of hydrogen peroxide, either orally or by injection and is, in general, based around 2 precepts. Firstly that hydrogen peroxide is naturally produced by the body to combat infection. Secondly, that human [[pathogens]] (including cancer: See [[Warburg hypothesis]]) are [[Anaerobic respiration|anaerobic]] and cannot survive in oxygen-rich environments. The ingestion or injection of hydrogen peroxide is therefore believed to kill disease by mimicking the immune response in addition to increasing levels of oxygen within the body. This makes it similar to other oxygen-based therapies, such as [[ozone therapy]] and [[hyperbaric oxygen therapy]].
Formerly inorganic processes were used, employing the [[electrolysis]] of an aqueous solution of [[sulfuric acid]] or acidic [[ammonium bisulfate]] (NH<sub>4</sub>HSO<sub>4</sub>), followed by [[hydrolysis]] of the peroxydisulfate ((SO<sub>4</sub>)<sub>2</sub>)<sup>2−</sup> which is formed.
Both the effectiveness and safety of hydrogen peroxide therapy is disputed by mainstream scientists. Hydrogen peroxide is produced by the immune system but in a carefully controlled manner. Cells called by [[phagocyte]]s engulf pathogens and then use hydrogen peroxide to destroy them. The peroxide is toxic to both the cell and the pathogen and so is kept within a special compartment, called a [[phagosome]]. Free hydrogen peroxide will damage any tissue it encounters via [[oxidative stress]]; a process which also has been proposed as a cause of cancer.<ref>{{cite journal|last=Halliwell|first=Barry|title=Oxidative stress and cancer: have we moved forward?|journal=Biochemical Journal|date=1 January 2007|volume=401|issue=1|pages=1–11|doi=10.1042/BJ20061131|pmid=17150040}}</ref>
Claims that hydrogen peroxide therapy increase cellular levels of oxygen have not been supported. The quantities administered would be expected to provide very little additional oxygen compared to that available from normal respiration. It should also be noted that it is difficult to raise the level of oxygen around cancer cells within a tumour, as the blood supply tends to be poor, a situation known as [[tumor hypoxia]].
In 1994, world production of H<sub>2</sub>O<sub>2</sub> was around 1.9 million [[tonne]]s, most of which was at a concentration of 70% or less. In that year bulk 30% H<sub>2</sub>O<sub>2</sub> sold for around US $0.54 per [[Kilogram|kg]], equivalent to US $1.50 per kg (US $0.68 per [[pound (mass)|lb]]) on a "100% basis".
Large oral doses of hydrogen peroxide at a 3% concentration may cause irritation and blistering to the mouth, throat, and abdomen as well as abdominal pain, vomiting, and diarrhea.<ref name="largeOral">[http://www.sefsc.noaa.gov/HTMLdocs/HydrogenPeroxide3.htm Hydrogen Peroxide, 3%. 3. Hazards Identification] Southeast Fisheries Science Center, daughter agency of [[NOAA]].</ref>
[[intravenous therapy|Intravenous injection]] of hydrogen peroxide has been linked to several deaths.<ref name="deaths">{{Cite news|last=Cooper|first=Anderson|title=A Prescription for Death?|publisher=CBS News|date=12 January 2005|url=http://www.cbsnews.com/stories/2005/01/12/60II/main666489.shtml|accessdate=7 July 2007}}</ref><ref>{{cite web|last=Mikkelson|first=Barbara|title=Hydrogen Peroxide|url=http://www.snopes.com/medical/healthyself/peroxide.asp|publisher=Snopes.com|date=30 April 2006|accessdate=7 July 2007}}</ref><ref>{{cite web|url=http://www.thedenverchannel.com/news/naturopath-sentenced-for-injecting-teen-with-hydrogen-peroxide |title=Naturopath Sentenced For Injecting Teen With Hydrogen Peroxide - 7NEWS Denver |publisher=Thedenverchannel.com |date=2006-03-27 |accessdate=2015-02-14}}</ref>
==Concentration==
The [[American Cancer Society]] states that "there is no scientific evidence that hydrogen peroxide is a safe, effective or useful cancer treatment"<ref name="baddrink">{{Cite journal|title=Questionable methods of cancer management: hydrogen peroxide and other 'hyperoxygenation' therapies |journal=CA: a cancer journal for clinicians|volume=43|issue=1|pages=47–56|year=1993|pmid=8422605|doi=10.3322/canjclin.43.1.47}}</ref> The therapy is not approved by the U.S. FDA.
Hydrogen peroxide works best as a propellant in extremely high concentrations-- roughly over 70%. Although any concentration of peroxide will generate ''some'' hot gas (oxygen plus some steam), at concentrations above approximately 67%, the heat of decomposing hydrogen peroxide becomes large enough to ''completely'' vaporize ''all'' the liquid at standard temperature. This represents a safety and utilization turning point, since decomposition of any concentration ''above'' this amount is capable of transforming the liquid ''entirely'' to heated gas (the higher the concentration, the hotter the resulting gas). This very hot steam/oxygen mixture can then be used to generate maximal thrust, power, or work, but it also makes explosive decomposition of the material far more hazardous.
===Propellant===
{{details|High-test peroxide}}
[[File:Rocket Belt Propulsion.png|thumb|200px|Rocket Belt hydrogen peroxide propulsion system used in a [[jet pack]]]]
Normal propellant grade concentrations therefore vary from 70 to 98%, with common grades of 70, 85, 90, and 98%. Many of these grades and variations are described in detail in the United States propellant specification number MIL-P-16005 Revision F, which is currently available. The available suppliers of high concentration propellant grade hydrogen peroxide are generally one of the large commercial companies which make other grades of hydrogen peroxide; including [[Solvay|Solvay Interox]], [[FMC]], [[Degussa]] and [http://www.peroxidepropulsion.com/ Peroxide Propulsion]. Other companies which have made propellant grade hydrogen peroxide in the recent past include [[Air Liquide]] and [[DuPont]]. DuPont recently sold its hydrogen peroxide manufacturing business to Degussa.
High concentration {{chem|H|2|O|2}} is referred to as High Test Peroxide (HTP). It can be used either as a [[monopropellant]] (not mixed with fuel) or as the oxidizer component of a [[bipropellant rocket]]. Use as a monopropellant takes advantage of the decomposition of 70–98+% concentration hydrogen peroxide into steam and oxygen. The propellant is pumped into a reaction chamber where a catalyst, usually a silver or platinum screen, triggers decomposition, producing steam at over 600 °C (1,112 °F), which is expelled through a [[nozzle]], generating [[thrust]]. {{chem|H|2|O|2}} monopropellant produces a maximum [[specific impulse]] (''I''<sub>sp</sub>) of 161 s (1.6 [[newton-second|kN·s]]/kg). Peroxide was the first major monopropellant adopted for use in rocket applications. [[Hydrazine]] eventually replaced hydrogen peroxide monopropellant thruster applications primarily because of a 25% increase in the vacuum specific impulse.<ref>http://www.hydrogen-peroxide.us/history-US-General-Kinetics/AIAA-2006-5236_hydrogen_peroxide_versus_hydrazine.pdf</ref> Hydrazine (toxic) and hydrogen peroxide (non-toxic) are the only two monopropellants (other than cold gases) to have been widely adopted and utilized for propulsion and power applications. The [[Bell Rocket Belt]], reaction control systems for X-1, X-15, Centaur, Mercury, Little Joe as well as the turbo-pump gas generators for X-1, X-15, Jupiter, Redstone and Viking used hydrogen peroxide as a monopropellant.<ref>http://www.hydrogen-peroxide.us/uses-monoprop-steam-generation/AIAA-1999-2880_The_Use_of_Hydrogen_Peroxide_for_Propulsion_and_Power-pitch.pdf</ref>
Propellant grade hydrogen peroxide is available to qualified buyers. Typically this chemical is only sold to commercial companies or government institutions which have the ability to properly handle and utilize the material. Non-professionals have purchased 70% or lower concentration hydrogen peroxide (the remaining 30% is water with traces of impurities and stabilizing materials, such as tin salts, phosphates, nitrates, and other chemical additives), and increased its concentration themselves. Many amateurs try [[distillation]], but this is extremely dangerous with hydrogen peroxide; peroxide vapor can ignite or detonate depending on specific combinations of temperature and pressure. In general any boiling mass of high concentration hydrogen peroxide at ambient pressure will produce vapor phase hydrogen peroxide which can detonate. This hazard is mitigated, but not entirely eliminated with vacuum distillation. Other approaches for concentrating hydrogen peroxide are [[sparging]] and [[fractional crystallization]].
As a bipropellant {{chem|H|2|O|2}} is decomposed to burn a fuel as an oxidizer. Specific impulses as high as 350 s (3.5 kN·s/kg) can be achieved, depending on the fuel. Peroxide used as an oxidizer gives a somewhat lower ''I''<sub>sp</sub> than liquid oxygen, but is dense, storable, noncryogenic and can be more easily used to drive gas turbines to give high pressures using an efficient ''closed cycle''. It can also be used for regenerative cooling of rocket engines. Peroxide was used very successfully as an oxidizer in World War II German rocket motors (e.g. [[T-Stoff]], containing oxyquinoline stabilizer, for the [[Me 163]]B), most often used with [[C-Stoff]] in a self-igniting [[hypergolic]] combination, and for the low-cost British [[Black Knight (rocket)|Black Knight]] and [[Black Arrow]] launchers. <!--{{cite web
| title = Hydrogen Peroxide for Power and Propulsion}}-->
High concentration hydrogen peroxide is readily available in 70, 90, and 98% concentrations in sizes of 1 gallon, 30 gallon, and bulk tanker truck volumes. Propellant grade hydrogen peroxide is being used on current military systems and is in numerous defense and aerospace research and development programs. Many privately funded rocket companies are using hydrogen peroxide, notably [[Blue Origin]], and some amateur groups have expressed interest in manufacturing their own peroxide, for their use and for sale in small quantities to others.
In the 1940s and 1950s, the [[Hellmuth Walter|Walter]] [[gas turbine|turbine]] used hydrogen peroxide for use in [[submarine]]s while submerged; it was found to be too noisy and require too much maintenance compared to [[Submarine#Propulsion|diesel-electric]] power systems. Some [[torpedo]]es used hydrogen peroxide as oxidizer or propellant. Operator error in the use of hydrogen peroxide torpedoes were named as possible causes for the sinkings of [[HMS Sidon (P259)|HMS ''Sidon'']] and the [[Russian submarine Kursk|Russian submarine ''Kursk'']].<ref>{{cite web|url=http://www.histarmar.com.ar/InfGral/SubmarinosAcc/Peroxide%20Accident%20-%20Walter%20Web%20Site.htm |title=Peroxide Accident - Walter Web Site |publisher=Histarmar.com.ar |accessdate=2015-02-14}}</ref> SAAB Underwater Systems is manufacturing the Torpedo 2000. This torpedo, used by the Swedish navy, is powered by a piston engine propelled by HTP as an oxidizer and [[kerosene]] as a fuel in a bipropellant system.<ref>{{Cite journal|last=Scott|first=Richard |date=November 1997|title=Homing Instincts|journal=Jane's Navy Steam generated by catalytic decomposition of 80–90% hydrogen peroxide was used for driving the turbopump turbines of the V-2 rockets, the X-15 rocketplanes, the early Centaur RL-10 engines and is still used on [[Soyuz (rocket family)|Soyuz]] for that purpose to-day. International|url=http://babriet.tripod.com/articles/art_hominginstinct.htm}}</ref><ref>[http://www.nasa.gov/mission_pages/station/structure/elements/soyuz/landing.html Soyuz using hydrogen peroxide propellant] ([[NASA]] website)</ref>
== Hazards ==
==== Explosives ====
Hydrogen peroxide, either in pure or diluted form, can pose several risks:
Hydrogen peroxide has been used for creating [[organic peroxide]] based explosives, such as [[acetone peroxide]], for [[improvised explosive devices]], including the [[7 July 2005 London bombings]].<ref name=homebomb>[http://www.nbcnews.com/id/32976055/ns/us_news-security/t/tiny-cheap-deadly-hydrogen-peroxide-bombs/ Tiny cheap deadly hydrogen peroxide bombs], 2009 article about home made bombs and their use in terror attacks. ([[NBC News]])</ref> These explosives tend to degrade quickly and hence are not used as commercial or military explosives.
* Above roughly 70% concentrations, hydrogen peroxide can give off vapor that can detonate above 70 °C (158 °F) at normal atmospheric pressure. This can then cause a boiling liquid expanding vapor explosion ([[BLEVE]]) of the remaining liquid. [[Distillation]] of hydrogen peroxide at normal pressures is thus highly dangerous.
* Hydrogen peroxide vapors can form sensitive contact explosives with hydrocarbons such as greases. Hazardous reactions ranging from ignition to explosion have been reported with [[alcohol]]s, [[ketone]]s, [[carboxylic acid]]s (particularly [[acetic acid]]), [[amine]]s and [[phosphorus]]. The saying is 'peroxides kill chemists'.
===Other uses===
[[File:Chemiluminescance.JPG|thumbnail|right|[[Chemiluminescence]] of [[cyalume]], as found in a glow stick]]
* Hydrogen peroxide, if spilled on clothing (or other flammable materials), will preferentially evaporate water until the concentration reaches sufficient strength, then clothing will spontaneously ignite. Leather generally contains metal ions from the tanning process and will often catch fire almost immediately.<ref>[http://media.armadilloaerospace.com/misc/MaterialTest.mpg Armadilloaerospace material tests with HTP]</ref> <!-- videos demonstrations are generally not reliable sources per WP:RS, and this particular video doesn't actually verify (per WP:V) the information contained in this paragraph. -->
Hydrogen peroxide has various domestic uses, primarily as a cleaning and disinfecting agent.
* Concentrated hydrogen peroxide (>50%) is corrosive, and even domestic-strength solutions can cause irritation to the eyes, [[mucous membrane]]s and skin.<ref>For example, see an [http://www.jtbaker.com/msds/englishhtml/h4070.htm MSDS for a 3% peroxide solution].</ref> Swallowing hydrogen peroxide solutions is particularly dangerous, as decomposition in the stomach releases large quantities of gas (10 times the volume of a 3% solution) leading to internal bleeding. Inhaling over 10% can cause severe pulmonary irritation.
;Glow sticks
Hydrogen peroxide reacts with [[ester]]s, such as and [[phenyl oxalate ester]] (cyalume), to produce [[chemiluminescence]]; this application is most commonly encountered in the form of [[glow stick]]s.
* Low concentrations of hydrogen peroxide, on the order of 3% or less, will chemically stain any clothing it comes into contact with a pinkish hue. Extreme care should be exercised when using common products that may contain hydrogen peroxide, such as facial cleaner or contact lens solution, which easily splatter upon other surfaces.
;Horticulture:
Some horticulturalists and users of [[hydroponics]] advocate the use of weak hydrogen peroxide solution in watering solutions. Its spontaneous decomposition releases oxygen that enhances a plant's root development and helps to treat [[root rot]] (cellular root death due to lack of oxygen) and a variety of other pests.<ref>{{cite web| url = http://www.socalplumeriacare.com/Faqs/F-7.pdf | title = Hydrogen Peroxide and Horticulture | first = Bryce | last = Fredrickson | accessdate = 25 January 2009}}</ref><ref>[http://www.using-hydrogen-peroxide.com/peroxide-garden.html Ways to use hydrogen peroxide in the garden]</ref><ref>{{cite journal |author=Bhattarai SP, Su N, Midmore DJ |title=Oxygation Unlocks Yield Potentials of Crops in Oxygen-Limited Soil Environments |journal=Advances in Agronomy |volume=88 |pages=313–377 |year=2005 |doi=10.1016/S0065-2113(05)88008-3 |url=http://www.sciencedirect.com/science/article/pii/S0065211305880083 |series=Advances in Agronomy |isbn=9780120007868|last2=Su |last3=Midmore }}</ref>
Hydrogen peroxide is naturally produced as a byproduct of oxygen metabolism, and virtually all organisms possess enzymes known as [[peroxidase]]s, which apparently harmlessly catalytically decomposes low concentrations of hydrogen peroxide to water and oxygen (''see [[#Decomposition|Decomposition]] above'').
;Fish aeration
Laboratory tests conducted by fish culturists in recent years have demonstrated that common household hydrogen peroxide can be used safely to provide oxygen for small fish. The hydrogen peroxide releases oxygen by decomposition when it is exposed to [[catalysts]] such as [[manganese dioxide]].<ref>[http://www.great-lakes.org/Wkly_news/07-07-03.html#Oxygen Great-lakes.org]</ref><ref>[http://www.fws.gov/midwest/ashland/mtan/mtan_35.html#Guide%20to%20Drug,%20Vaccine,%20and%20Pesticide%20Use%20in%20Aquaculture fws.gov]</ref>
In one incident, several people were injured after a hydrogen peroxide spill on board [[Northwest Airlines Flight 957]] because they mistook it for water.<ref>Hazardous Materials Incident Brief DCA-99-MZ-001, [http://www.ntsb.gov/publictn/2000/HZB0001.htm "Spill of undeclared shipment of hazardous materials in cargo compartment of aircraft"]. pub: National Transportation Safety Board. October 28, 1998; adopted May 17, 2000.</ref>
==Safety==
Regulations vary, but low concentrations, such as 6%, are widely available and legal to buy for medical use. Most over-the-counter peroxide solutions are not suitable for ingestion. Higher concentrations may be considered hazardous and are typically accompanied by a [[Material Safety Data Sheet]] (MSDS). In high concentrations, hydrogen peroxide is an aggressive oxidizer and will corrode many materials, including human skin. In the presence of a [[reducing agent]], high concentrations of will react violently.
Hydrogen peroxide was also part of the ingredients in the July 21, 2005 London Underground bombs, which failed to explode.<ref>Four Men Found Guilty in Plot to Blow Up London’s Transit System, [http://www.foxnews.com/story/0,2933,288631,00.html "FOXNews.com"]. (July 9, 2007)</ref>
High-concentration hydrogen peroxide streams, typically above 40%, should be considered hazardous due to concentrated hydrogen peroxide's meeting the definition of a [[United States Department of Transportation|DOT]] oxidizer according to U.S. regulations, if released into the environment. The [[United States Environmental Protection Agency|EPA]] Reportable Quantity (RQ) for D001 hazardous wastes is , or approximately , of concentrated hydrogen peroxide.
An [[MSDS]] will contain more information on the risks of working with this chemical.<!-- we should ideally list a few here, for various concentrations perhaps -->
Hydrogen peroxide should be stored in a cool, dry, well-ventilated area and away from any flammable or combustible substances.[[http://www.bu.edu/es/labsafety/ESMSDSs/MSHydPeroxide.html Hydrogen Peroxide MSDS]</ref> It should be stored in a container composed of non-reactive materials such as stainless steel or glass (other materials including some plastics and aluminium alloys may also be suitable).<ref>[http://www.ozoneservices.com/articles/004.htm Ozonelab Peroxide compatibility]</ref> Because it breaks down quickly when exposed to light, it should be stored in an opaque container, and pharmaceutical formulations typically come in brown bottles that filter out light.<ref>{{cite web|url = http://www.hydrogenperoxidemouthwash.org |title = Hydrogen Peroxide Mouthwash is it Safe? |accessdate = 30 Oct 2013}}</ref>
==References==
Hydrogen peroxide, either in pure or diluted form, can pose several risks, the main one being that it forms explosive mixtures upon contact with organic compounds.<ref name="osha safety guidelines" /> Highly concentrated hydrogen peroxide itself is unstable, and can then cause a [[boiling liquid expanding vapor explosion]] (BLEVE) of the remaining liquid. [[Distillation]] of hydrogen peroxide at normal pressures is thus highly dangerous. It is also corrosive especially when concentrated but even domestic-strength solutions can cause irritation to the eyes, [[mucous membrane]]s and skin.<ref name="hazards">For example, see an [http://hazard.com/msds/mf/baker/baker/files/h4070.htm MSDS for a 3% peroxide solution].</ref> Swallowing hydrogen peroxide solutions is particularly dangerous, as decomposition in the stomach releases large quantities of gas (10 times the volume of a 3% solution) leading to internal bleeding. Inhaling over 10% can cause severe pulmonary irritation.<ref name="atsdr toxic facts">[http://www.atsdr.cdc.gov/toxfaqs/tfacts174.pdf H2O2 toxicity and dangers] [[Agency for Toxic Substances and Disease Registry]] website</ref>
{{refbegin}}
* J. Drabowicz ''et al.'', in ''The Syntheses of Sulphones, Sulphoxides and Cyclic Sulphides'', p112-116, G. Capozzi ''et al.'', eds., John Wiley & Sons, Chichester, UK, 1994. ISBN 0-471-93970-6.
* N. N. Greenwood, A. Earnshaw, ''Chemistry of the Elements'', 2nd ed., Butterworth-Heinemann, Oxford, UK, 1997. A great description of properties & chemistry of H<sub>2</sub>O<sub>2</sub>.
* J. March, ''Advanced Organic Chemistry'', 4th ed., p. 723, Wiley, New York, 1992.
* W. T. Hess, ''Hydrogen Peroxide'', in ''Kirk-Othmer Encyclopedia of Chemical Technology'', 4th edition, Wiley, New York, Vol. 13, 961-995 (1995).
{{refend}}
{{reflist|2}}
The Society Of Chemical Industry article (Googol cached article) re: new hydrogen peroxide/methyl alchohol catalyst
With a significant vapor pressure (1.2 kPa at 50 °C[CRC Handbook of Chemistry and Physics, 76th Ed, 1995–1996]), hydrogen peroxide vapor is potentially hazardous. According to U.S. NIOSH, the Immediately Dangerous to Life and Health (IDLH) limit is only 75 ppm.<ref name="dangerous concentrations">[http://www.cdc.gov/niosh/idlh/intridl4.html Documentation for Immediately Dangerous to Life or Health Concentrations (IDLH): NIOSH] National Institute for Occupational Safety and Health] Chemical Listing and Documentation of Revised IDLH Values (as of 3/1/95)]</ref> The U.S. [[Occupational Safety and Health Administration]] (OSHA) has established a permissible exposure limit of 1.0 ppm calculated as an eight-hour time weighted average (29 CFR 1910.1000, Table Z-1)<ref name="osha safety guidelines">[http://www.osha.gov/SLTC/healthguidelines/hydrogenperoxide/recognition.html Occupational Safety and Health Guideline for Hydrogen Peroxide]</ref> and hydrogen peroxide has also been classified by the [[American Conference of Governmental Industrial Hygienists]] (ACGIH) as a "known animal carcinogen, with unknown relevance on humans."<ref name="carcinogen">[http://www2.worksafebc.com/PDFs/regulation/exposure_limits.pdf Threshold Limit Values for Chemical Substances and Physical Agents & Biological Exposure Indices, ACGIH]</ref> For workplaces where there is a risk of exposure to the hazardous concentrations of the vapors, continuous monitors for hydrogen peroxide should be used. Information on the hazards of hydrogen peroxide is available from OSHA<ref name="osha safety guidelines" /> and from the ATSDR.<ref name="atsdr toxic substance">[http://www.atsdr.cdc.gov/MHMI/mmg174.html Agency for Toxic Substances and Disease Registry]</ref>
[[User:89.129.141.95|89.129.141.95]] 16:50, 2 October 2007 (UTC)
==External links==
===Historical incidents===
* [http://msds.fmc.com/msds/100000010225-MSDS_US-E.pdf Material Safety Data Sheet]
* On 16 July 1934, in [[Kummersdorf]], Germany, a propellant tank containing an experimental monopropellant mixture consisting of hydrogen peroxide and ethanol exploded during a test, killing three people.
* [http://www.atsdr.cdc.gov/tfactsx4.html ATSDR Agency for Toxic Substances and Disease Registry FAQ]
* During the [[World War II|Second World War]], doctors in [[Nazi concentration camps|German concentration camps]] experimented with the use of hydrogen peroxide injections in the killing of human subjects.<ref>{{cite web| title=The Nazi Doctors: Medical Killing and the Psychology of Genocide | publisher=Robert Jay Lifton | url=http://www.holocaust-history.org/lifton/LiftonT257.shtml | accessdate=1 November 2007}}</ref>
* Several people received minor injuries after a hydrogen peroxide spill on board a flight between the U.S. cities Orlando and Memphis on 28 October 1998.<ref>Hazardous Materials Incident Brief DCA-99-MZ-001, [http://www.ntsb.gov/doclib/reports/2000/hzb0001.pdf "Spill of undeclared shipment of hazardous materials in cargo compartment of aircraft"]. pub: National Transportation Safety Board. 28 October 1998; adopted 17 May 2000.</ref>
* The Russian submarine K-141 ''Kursk'' sailed to perform an exercise of firing dummy torpedoes at the [[Russian battlecruiser Pyotr Velikiy|Pyotr Velikiy]], a [[Kirov class battlecruiser]]. On 12 August 2000 at 11:28 local time (07:28 UTC), [[Russian submarine Kursk explosion|there was an explosion]] while preparing to fire the torpedoes. The only credible report to date is that this was due to the failure and explosion of one of the Kursk's hydrogen peroxide-fueled torpedoes. It is believed that [[High test peroxide|HTP]], a form of highly concentrated hydrogen peroxide used as propellant for the torpedo, seeped through rust in the torpedo casing. The vessel was lost with all hands. A similar incident was responsible for the loss of [[HMS Sidon (P259)|HMS Sidon]] in 1955.
* [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc01/icsc0164.htm International Chemical Safety Card 0164]
* On 15 August 2010 a spill of about of cleaning fluid occurred on the 54th floor of 1515 Broadway, in Times Square, New York City. The spill, which a spokesperson for the New York City fire department said was of hydrogen peroxide, shut down Broadway between West 42nd and West 48th streets as fire engines responded to the [[HAZMAT|hazmat]] situation. There were no reported injuries.<ref>{{cite news|title=Bleach Spill Shuts Part of Times Square|url=http://www.nytimes.com/2010/08/16/nyregion/16square.html|date=16 August 2010 | work=The New York Times|first=Sarah|last=Wheaton}}</ref>
* [http://www.cdc.gov/niosh/npg/npgd0335.html NIOSH Pocket Guide to Chemical Hazards]
* [http://www.gkllc.com General Kinetics Inc. Hydrogen Peroxide Rocket Engines and Gas Generators]
* [http://www.quackwatch.org/01QuackeryRelatedTopics/Cancer/oxygen.html Oxygenation Therapy:Unproven Treatments for Cancer and AIDS]
* [http://www.flywriterproductions.com/sites/themolecule/index.html H2O2 and HYPER OXYGEN THERAPY]
* [http://news.bbc.co.uk/1/hi/england/london/4197500.stm Explosion of a lorry carrying hydrogen peroxide closes M25 motorway.]
* [http://www.gaiaresearch.co.za/hydroperoxide.html Hydrogen Peroxide in the Human Body]
* [http://www.using-hydrogen-peroxide.com Information on many common uses for hydrogen peroxide, especially household uses.]
*[http://copublications.greenfacts.org/en/tooth-whiteners/index.htm Hydrogen peroxide in tooth whiteners] summary by [[GreenFacts]] of the European Commission SCCP assessment
Hydrogen peroxide is often described as being “water but with one more oxygen atom” a description which can give the incorrect impression that there is a great deal of similarity between the two compounds. Pure hydrogen peroxide will explode if heated to boiling, will cause serious contact burns to the skin and can set materials alight on contact. For these reasons it is usually handled as a dilute solution (household grades are typically 3-6%). Its chemistry is dominated by the nature of its unstable peroxide bond.
Structure and properties
Properties
The boiling point of H 2O 2 has been extrapolated as being 150.2 °C, approximately 50 degrees higher than water; in practice hydrogen peroxide will undergo potentially explosive thermal decomposition if heated to this temperature. It may be safely distilled under reduced pressure.[3]
In aqueous solutions
In aqueous solutions hydrogen peroxide differs from the pure material due to the effects of hydrogen bonding between water and hydrogen peroxide molecules. Hydrogen peroxide and water form a eutectic mixture, exhibiting freezing-point depression; pure water has a melting point of 0 °C and pure hydrogen peroxide of −0.43 °C, but a 50% (by volume) solution of the two freezes at -51 °C. The boiling point of the same mixtures is also depressed in relation with the median of both boiling points (125.1 °C). It occurs at 114 °C. This boiling point is 14° greater than that of pure water and 36.2° less than that of pure hydrogen peroxide.[4]
Density of aqueous solution of H2O2
H2O2 (w/w)
Density (g/cm3)
Temperature (°C)
3%
1.0095
15
27%
1.10
20
35%
1.13
20
50%
1.20
20
70%
1.29
20
75%
1.33
20
96%
1.42
20
98%
1.43
20
100%
1.450
20
Structure
Hydrogen peroxide (H 2O 2), is a nonplanar molecule with (twisted) C2symmetry. Although the O−O bond is a single bond, the molecule has a relatively high barrier to rotation of 2460 cm−1 (29.45 kJ/mol);[5] for comparison, the rotational barrier for ethane is 12.5 kJ/mol. The increased barrier is ascribed to repulsion between the lone pairs of the adjacent oxygen atoms and results in hydrogen peroxide displaying atropisomerism.
The molecular structures of gaseous and crystallineH 2O 2 are significantly different. This difference is attributed to the effects of hydrogen bonding, which is absent in the gaseous state.[6] Crystals of H 2O 2 are tetragonal with the space group <math>D_4^4 P4_12_1</math>.[7]
Hydrogen peroxide has several structural analogues with Hm-E-E-Hn bonding arrangements (Water also shown for comparison). It has the highest (theoretical) boiling point of this series (X = O, N, S). Its melting point is also fairly high, being comparable to that of hydrazine and water, with only hydroxylamine crystallising significantly more readily, indicative of particularly strong hydrogen bonding. Diphosphane and hydrogen disulfide exhibit only weak hydrogen bonding and have little chemical similarity to hydrogen peroxide. All of these analogues are thermodynamically unstable. Structurally, the analogues all adopt similar skewed structures, due to repulsion between adjacent lone pairs.
Pure hydrogen peroxide was long believed to be unstable as early attempts to separate it from the water, which is present during synthesis, all failed. This instability was due to traces of impurities (transition metalssalts) which catalyze the decomposition of the hydrogen peroxide. Pure hydrogen peroxide was first obtained in 1894 — almost 80 years after its discovery — by Richard Wolffenstein, who produced it via vacuum distillation.[10]
Determination of the molecular structure of hydrogen peroxide proved to be very difficult. In 1892 the Italian physical chemist Giacomo Carrara (1864–1925) determined its molecular weight by freezing point depression, which confirmed that its molecular formula is H2O2.[11] At least half a dozen hypothetical molecular structures seemed to be consistent with the available evidence.[12] In 1934, the English mathematical physicist William Penney and the Scottish physicist Gordon Sutherland proposed a molecular structure for hydrogen peroxide which was very similar to the presently accepted one.[13]
Today, hydrogen peroxide is manufactured almost exclusively by the anthraquinone process, which was formalized in 1936 and patented in 1939. It begins with the reduction of an anthraquinone (such as 2-ethylanthraquinone or the 2-amyl derivative) to the corresponding anthrahydroquinone, typically via hydrogenation on a palladiumcatalyst; the anthrahydroquinone then undergoes to autoxidation to regenerate the starting anthraquinone, with hydrogen peroxide being produced as a by-product. Most commercial processes achieve oxidation by bubbling compressed air through a solution of the derivatized anthracene, whereby the oxygen present in the air reacts with the labile hydrogen atoms (of the hydroxy group), giving hydrogen peroxide and regenerating the anthraquinone. Hydrogen peroxide is then extracted and the anthraquinone derivative is reduced back to the dihydroxy (anthracene) compound using hydrogen gas in the presence of a metal catalyst. The cycle then repeats itself.[14][15]
The simplified overall equation for the process is deceptively simple:[14]
H 2 + O 2 → H 2O 2
The economics of the process depend heavily on effective recycling of the quinone (which is expensive) and extraction solvents, and of the hydrogenationcatalyst.
A process to produce hydrogen peroxide directly from the elements has been of interest for many years. Direct synthesis is difficult to achieve as, in terms of thermodynamics, the reaction of hydrogen with oxygen favours production of water. Systems for direct synthesis have been developed; most of which are based around finely dispersed metal catalysts.[16][17] None of these has yet reached a point where they can be used for industrial-scale synthesis.
Availability
Hydrogen peroxide is most commonly available as a solution in water. For consumers, it is usually available from pharmacies at 3 and 6 wt% concentrations. The concentrations are sometimes described in terms of the volume of oxygen gas generated; one milliliter of a 20-volume solution generates twenty milliliters of oxygen gas when completely decomposed. For laboratory use, 30 wt% solutions are most common. Commercial grades from 70% to 98% are also available, but due to the potential of solutions of more than 68% hydrogen peroxide to be converted entirely to steam and oxygen (with the temperature of the steam increasing as the concentration increases above 68%) these grades are potentially far more hazardous, and require special care in dedicated storage areas. Buyers must typically allow inspection by commercial manufacturers.
In 1994, world production of H 2O 2 was around 1.9 million tonnes and grew to 2.2 million in 2006,[18] most of which was at a concentration of 70% or less. In that year bulk 30% H 2O 2 sold for around US $0.54 per kg, equivalent to US $1.50 per kg (US $0.68 per lb) on a "100% basis".[19][20]
Reactions
Decomposition
Hydrogen peroxide is thermodynamically unstable and decomposes to form water and oxygen with a ΔHo of −98.2 kJ·mol−1 and a ΔS of 70.5 J·mol−1·K−1.
2 H 2O 2 → 2 H 2O + O 2
The rate of decomposition increases with rising temperature, concentration and pH, with cool, dilute, acidic solutions showing the best stability. Decomposition is catalysed by various compounds, including most transition metals and their compounds (e.g. manganese dioxide, silver, and platinum).[21] Certain metal ions, such as Fe2+ or Ti3+ , can cause the decomposition to take a different path, with free radicals such as (HO·) and (HOO·) being formed.
Non-metallic catalysts include potassium iodide, which reacts particularly rapidly and forms the basis of the elephant toothpaste experiment. Hydrogen peroxide can also be decomposed biologically by enzymecatalase.
The decomposition of hydrogen peroxide liberates oxygen and heat; this can be dangerous as spilling high concentrations of hydrogen peroxide on a flammable substance can cause an immediate fire.
Redox reactions
Hydrogen peroxide exhibits oxidizing and reducing properties, depending on pH.
In acidic solutions Fe2+ is oxidized to Fe3+ (hydrogen peroxide acting as an oxidizing agent),
2 Fe2+ (aq) + H 2O 2 + 2 H+ (aq) → 2 Fe3+ (aq) + 2 H 2O(l)
and sulfite (SO2− 3) is oxidized to sulfate (SO2− 4). However, potassium permanganate is reduced to Mn2+ by acidic H 2O 2. Under alkaline conditions, however, some of these reactions reverse; for example, Mn2+ is oxidized to Mn4+ (as MnO 2).
In basic solution, hydrogen peroxide can reduce a variety of inorganic ions. When it acts as a reducing agent, oxygen gas is also produced. For example hydrogen peroxide will reduce sodium hypochlorite and potassium permanganate, which is a convenient method for preparing oxygen in the laboratory.
NaOCl + H 2O 2 → O 2 + NaCl + H 2O
2 KMnO 4 + 3 H 2O 2 → 2 MnO 2 + 2 KOH + 2 H 2O + 3 O 2
It also converts metal oxides into the corresponding peroxides. For example, upon treatment with hydrogen peroxide, chromic acid (CrO 3) form an unstable blue peroxide CrO(O 2) 2.
This kind of reaction is used industrially to produce peroxoanions. For example, reaction with borax leads to sodium perborate, a bleach used in laundry detergents:
Na 2B 4O 7 + 4 H 2O 2 + 2 NaOH → 2 Na 2B 2O 4(OH) 4 + H 2O
Hydrogen peroxide is also one of the two chief chemicals in the defense system of the bombardier beetle, reacting with hydroquinone to discourage predators.
A study published in Nature found that hydrogen peroxide plays a role in the immune system. Scientists found that hydrogen peroxide presence inside cells increased after tissues are damaged in zebra fish, which is thought to act as a signal to white blood cells to converge on the site and initiate the healing process. When the genes required to produce hydrogen peroxide were disabled, white blood cells did not accumulate at the site of damage. The experiments were conducted on fish; however, because fish are genetically similar to humans, the same process is speculated to occur in humans. The study in Nature suggested asthma sufferers have higher levels of hydrogen peroxide in their lungs than healthy people, which could explain why asthma sufferers have inappropriate levels of white blood cells in their lungs.[24][25]
Hydrogen peroxide has important roles as a signaling molecule in the regulation of a wide variety of biological processes.[26] The compound is a major factor implicated in the free-radical theory of aging, based on how readily hydrogen peroxide can decompose into a hydroxyl radical and how superoxide radical byproducts of cellular metabolism can react with ambient water to form hydrogen peroxide.[27] These hydroxyl radicals in turn readily react with and damage vital cellular components, especially those of the mitochondria.[28] At least one study has also tried to link hydrogen peroxide production to cancer.[29] These studies have frequently been quoted in fraudulent treatment claims.[citation needed]
The amount of hydrogen peroxide in biological systems can be assayed using a fluorimetric assay.[30]
Hydrogen peroxide is used in certain waste-water treatment processes to remove organic impurities. This is achieved by advanced oxidation processes, such as the Fenton reaction,[31][32] which use it to generate highly reactive hydroxyl radicals (·OH). These are able to destroy organic contaminates which are ordinarily difficult to remove, such as aromatic or halogenated compounds.[33] It can also oxidize sulphur based compounds present in the waste; which is beneficial as it generally reduces their odour.[34]
Medical
Disinfectant
Hydrogen peroxide can be used for the sterilization of various surfaces,[35] including surgical tools[36] and may be deployed as a vapor (VHP) for room sterilization.[37] H2O2 demonstrates broad-spectrum efficacy against viruses, bacteria, yeasts, and bacterial spores.[38] In general, greater activity is seen against gram-positive than gram-negative bacteria; however, the presence of catalase or other peroxidases in these organisms can increase tolerance in the presence of lower concentrations.[39] Higher concentrations of H2O2 (10 to 30%) and longer contact times are required for sporicidal activity.[40]
Historically hydrogen peroxide was used for disinfecting wounds, partly because of its low cost and prompt availability compared to other antiseptics. It is now thought to slow healing and lead to scarring because it destroys newly formed skin cells.[42] Only a very low concentration of H2O2 can induce healing, and only if not repeatedly applied.[43] Surgical use can lead to gas embolism formation.[44] Despite this it is still used for wound treatment in many developing countries.[45][46]
It is absorbed by skin upon contact and creates a local capillaryembolism that appears as a temporary whitening of the skin.[47]
Cosmetic applications
Diluted H 2O 2 (between 1.9% and 12%) mixed with ammonium hydroxide is used to bleach human hair. The chemical's bleaching property lends its name to the phrase "peroxide blonde".[48]
Hydrogen peroxide is also used for tooth whitening and can be mixed with baking soda and salt to make a home-made toothpaste.[49]
Hydrogen peroxide may be used to treat acne,[50] although benzoyl peroxide is a more common treatment.
Use in alternative medicine
Practitioners of alternative medicine have advocated the use of hydrogen peroxide for the treatment of various conditions, including emphysema, influenza, AIDS and in particular cancer.[51] The practise calls for the daily consumption of hydrogen peroxide, either orally or by injection and is, in general, based around 2 precepts. Firstly that hydrogen peroxide is naturally produced by the body to combat infection. Secondly, that human pathogens (including cancer: See Warburg hypothesis) are anaerobic and cannot survive in oxygen-rich environments. The ingestion or injection of hydrogen peroxide is therefore believed to kill disease by mimicking the immune response in addition to increasing levels of oxygen within the body. This makes it similar to other oxygen-based therapies, such as ozone therapy and hyperbaric oxygen therapy.
Both the effectiveness and safety of hydrogen peroxide therapy is disputed by mainstream scientists. Hydrogen peroxide is produced by the immune system but in a carefully controlled manner. Cells called by phagocytes engulf pathogens and then use hydrogen peroxide to destroy them. The peroxide is toxic to both the cell and the pathogen and so is kept within a special compartment, called a phagosome. Free hydrogen peroxide will damage any tissue it encounters via oxidative stress; a process which also has been proposed as a cause of cancer.[52]
Claims that hydrogen peroxide therapy increase cellular levels of oxygen have not been supported. The quantities administered would be expected to provide very little additional oxygen compared to that available from normal respiration. It should also be noted that it is difficult to raise the level of oxygen around cancer cells within a tumour, as the blood supply tends to be poor, a situation known as tumor hypoxia.
Large oral doses of hydrogen peroxide at a 3% concentration may cause irritation and blistering to the mouth, throat, and abdomen as well as abdominal pain, vomiting, and diarrhea.[53]Intravenous injection of hydrogen peroxide has been linked to several deaths.[54][55][56]
The American Cancer Society states that "there is no scientific evidence that hydrogen peroxide is a safe, effective or useful cancer treatment"[57] The therapy is not approved by the U.S. FDA.
Rocket Belt hydrogen peroxide propulsion system used in a jet pack
High concentration H 2O 2 is referred to as High Test Peroxide (HTP). It can be used either as a monopropellant (not mixed with fuel) or as the oxidizer component of a bipropellant rocket. Use as a monopropellant takes advantage of the decomposition of 70–98+% concentration hydrogen peroxide into steam and oxygen. The propellant is pumped into a reaction chamber where a catalyst, usually a silver or platinum screen, triggers decomposition, producing steam at over 600 °C (1,112 °F), which is expelled through a nozzle, generating thrust. H 2O 2 monopropellant produces a maximum specific impulse (Isp) of 161 s (1.6 kN·s/kg). Peroxide was the first major monopropellant adopted for use in rocket applications. Hydrazine eventually replaced hydrogen peroxide monopropellant thruster applications primarily because of a 25% increase in the vacuum specific impulse.[58] Hydrazine (toxic) and hydrogen peroxide (non-toxic) are the only two monopropellants (other than cold gases) to have been widely adopted and utilized for propulsion and power applications. The Bell Rocket Belt, reaction control systems for X-1, X-15, Centaur, Mercury, Little Joe as well as the turbo-pump gas generators for X-1, X-15, Jupiter, Redstone and Viking used hydrogen peroxide as a monopropellant.[59]
As a bipropellant H 2O 2 is decomposed to burn a fuel as an oxidizer. Specific impulses as high as 350 s (3.5 kN·s/kg) can be achieved, depending on the fuel. Peroxide used as an oxidizer gives a somewhat lower Isp than liquid oxygen, but is dense, storable, noncryogenic and can be more easily used to drive gas turbines to give high pressures using an efficient closed cycle. It can also be used for regenerative cooling of rocket engines. Peroxide was used very successfully as an oxidizer in World War II German rocket motors (e.g. T-Stoff, containing oxyquinoline stabilizer, for the Me 163B), most often used with C-Stoff in a self-igniting hypergolic combination, and for the low-cost British Black Knight and Black Arrow launchers.
In the 1940s and 1950s, the Walterturbine used hydrogen peroxide for use in submarines while submerged; it was found to be too noisy and require too much maintenance compared to diesel-electric power systems. Some torpedoes used hydrogen peroxide as oxidizer or propellant. Operator error in the use of hydrogen peroxide torpedoes were named as possible causes for the sinkings of HMS Sidon and the Russian submarine Kursk.[60] SAAB Underwater Systems is manufacturing the Torpedo 2000. This torpedo, used by the Swedish navy, is powered by a piston engine propelled by HTP as an oxidizer and kerosene as a fuel in a bipropellant system.[61][62]
Some horticulturalists and users of hydroponics advocate the use of weak hydrogen peroxide solution in watering solutions. Its spontaneous decomposition releases oxygen that enhances a plant's root development and helps to treat root rot (cellular root death due to lack of oxygen) and a variety of other pests.[64][65][66]
Fish aeration
Laboratory tests conducted by fish culturists in recent years have demonstrated that common household hydrogen peroxide can be used safely to provide oxygen for small fish. The hydrogen peroxide releases oxygen by decomposition when it is exposed to catalysts such as manganese dioxide.[67][68]
Safety
Regulations vary, but low concentrations, such as 6%, are widely available and legal to buy for medical use. Most over-the-counter peroxide solutions are not suitable for ingestion. Higher concentrations may be considered hazardous and are typically accompanied by a Material Safety Data Sheet (MSDS). In high concentrations, hydrogen peroxide is an aggressive oxidizer and will corrode many materials, including human skin. In the presence of a reducing agent, high concentrations of will react violently.
High-concentration hydrogen peroxide streams, typically above 40%, should be considered hazardous due to concentrated hydrogen peroxide's meeting the definition of a DOT oxidizer according to U.S. regulations, if released into the environment. The EPA Reportable Quantity (RQ) for D001 hazardous wastes is , or approximately , of concentrated hydrogen peroxide.
Hydrogen peroxide should be stored in a cool, dry, well-ventilated area and away from any flammable or combustible substances.[Hydrogen Peroxide MSDS</ref> It should be stored in a container composed of non-reactive materials such as stainless steel or glass (other materials including some plastics and aluminium alloys may also be suitable).[69] Because it breaks down quickly when exposed to light, it should be stored in an opaque container, and pharmaceutical formulations typically come in brown bottles that filter out light.[70]
Hydrogen peroxide, either in pure or diluted form, can pose several risks, the main one being that it forms explosive mixtures upon contact with organic compounds.[71] Highly concentrated hydrogen peroxide itself is unstable, and can then cause a boiling liquid expanding vapor explosion (BLEVE) of the remaining liquid. Distillation of hydrogen peroxide at normal pressures is thus highly dangerous. It is also corrosive especially when concentrated but even domestic-strength solutions can cause irritation to the eyes, mucous membranes and skin.[72] Swallowing hydrogen peroxide solutions is particularly dangerous, as decomposition in the stomach releases large quantities of gas (10 times the volume of a 3% solution) leading to internal bleeding. Inhaling over 10% can cause severe pulmonary irritation.[73]
With a significant vapor pressure (1.2 kPa at 50 °C[CRC Handbook of Chemistry and Physics, 76th Ed, 1995–1996]), hydrogen peroxide vapor is potentially hazardous. According to U.S. NIOSH, the Immediately Dangerous to Life and Health (IDLH) limit is only 75 ppm.[74] The U.S. Occupational Safety and Health Administration (OSHA) has established a permissible exposure limit of 1.0 ppm calculated as an eight-hour time weighted average (29 CFR 1910.1000, Table Z-1)[71] and hydrogen peroxide has also been classified by the American Conference of Governmental Industrial Hygienists (ACGIH) as a "known animal carcinogen, with unknown relevance on humans."[75] For workplaces where there is a risk of exposure to the hazardous concentrations of the vapors, continuous monitors for hydrogen peroxide should be used. Information on the hazards of hydrogen peroxide is available from OSHA[71] and from the ATSDR.[76]
Historical incidents
On 16 July 1934, in Kummersdorf, Germany, a propellant tank containing an experimental monopropellant mixture consisting of hydrogen peroxide and ethanol exploded during a test, killing three people.
Several people received minor injuries after a hydrogen peroxide spill on board a flight between the U.S. cities Orlando and Memphis on 28 October 1998.[78]
The Russian submarine K-141 Kursk sailed to perform an exercise of firing dummy torpedoes at the Pyotr Velikiy, a Kirov class battlecruiser. On 12 August 2000 at 11:28 local time (07:28 UTC), there was an explosion while preparing to fire the torpedoes. The only credible report to date is that this was due to the failure and explosion of one of the Kursk's hydrogen peroxide-fueled torpedoes. It is believed that HTP, a form of highly concentrated hydrogen peroxide used as propellant for the torpedo, seeped through rust in the torpedo casing. The vessel was lost with all hands. A similar incident was responsible for the loss of HMS Sidon in 1955.
On 15 August 2010 a spill of about of cleaning fluid occurred on the 54th floor of 1515 Broadway, in Times Square, New York City. The spill, which a spokesperson for the New York City fire department said was of hydrogen peroxide, shut down Broadway between West 42nd and West 48th streets as fire engines responded to the hazmat situation. There were no reported injuries.[79]
↑Riley, edited by Georg Brauer ; translated by Scripta Technica, Inc. Translation editor Reed F. (1963). Handbook of preparative inorganic chemistry. Volume 1 (2nd ed.). New York, N.Y.: Academic Press. p. 140. ISBN978-0121266011.CS1 maint: Extra text: authors list (link)
↑Dougherty, Dennis A.; Eric V. Anslyn (2005). Modern Physical Organic Chemistry. University Science. p. 122. ISBN1-891389-31-9.
↑Abrahams, S. C.; Collin, R. L.; Lipscomb, W. N. (1 January 1951). "The crystal structure of hydrogen peroxide". Acta Crystallographica. 4 (1): 15–20. doi:10.1107/S0365110X51000039.
In his 1922 textbook, Joseph Mellor considered three hypothetical molecular structures for hydrogen peroxide, admitting (p. 952): " … the constitution of this compound has not been yet established by unequivocal experiments." See: Joseph William Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry, vol. 1 (London, England: Longmans, Green and Co., 1922), pages 952-956.
W. C. Schumb, C.N. Satterfield, and R.L. Wentworth (1 December 1953) "Report no. 43: Hydrogen peroxide, Part two," Office of Naval Research, Contract No. N5ori-07819 On p. 178, the authors present six hypothetical models for hydrogen peroxide's molecular structure. On p. 184, the present structure is considered almost certainly correct — although a small doubt remained. (Note: The report by Schumb et al. was reprinted as: W.C. Schumb, C.N. Satterfield, and R.L. Wentworth, Hydrogen Peroxide (New York, New York: Reinhold Publishing Corp. (American Chemical Society Monograph), 1955).)
W.G. Penney and G.B.B.M. Sutherland (1934) "The theory of the structure of hydrogen peroxide and hydrazine," Journal of Chemical Physics, 2 (8) : 492-498.
W.G. Penney and G.B.B.M. Sutherland (1934) "A note on the structure of H2O2 and H4N2 with particular reference to electric moments and free rotation," Transactions of the Faraday Society, 30 : 898-902.
↑ 14.014.1Jose M. Campos-Martin, Gema Blanco-Brieva, Jose L. G. Fierro; Blanco-Brieva; Fierro (2006). "Hydrogen Peroxide Synthesis: An Outlook beyond the Anthraquinone Process". Angewandte Chemie International Edition. 45 (42): 6962–6984. doi:10.1002/anie.200503779. PMID17039551.CS1 maint: Multiple names: authors list (link)
↑H. Riedl and G. Pfleiderer, U.S. Patent 2,158,525 (2 October 1936 in USA, and 10 October 1935 in Germany) to I. G. Farbenindustrie, Germany
↑Noritaka Mizuno Gabriele Centi, Siglinda Perathoner, Salvatore Abate "Direct Synthesis of Hydrogen Peroxide: Recent Advances" in Modern Heterogeneous Oxidation Catalysis: Design, Reactions and Characterization 2009, Wiley-VCH. doi:10.1002/9783527627547.ch8
↑Edwards, J. K.; Solsona, B.; N, E. N.; Carley, A. F.; Herzing, A. A.; Kiely, C. J.; Hutchings, G. J. (20 February 2009). "Switching Off Hydrogen Peroxide Hydrogenation in the Direct Synthesis Process". Science. 323 (5917): 1037–1041. Bibcode:2009Sci...323.1037E. doi:10.1126/science.1168980. PMID19229032.
↑ 18.018.1Ronald Hage, Achim Lienke; Lienke (2005). "Applications of Transition-Metal Catalysts to Textile and Wood-Pulp Bleaching". Angewandte Chemie International Edition. 45 (2): 206–222. doi:10.1002/anie.200500525. PMID16342123.
↑Weindruch, Richard (January 1996). "Calorie Restriction and Aging". Scientific American: 49–52.
↑Giorgio M, Trinei M, Migliaccio E, Pelicci PG; Trinei; Migliaccio; Pelicci (September 2007). "Hydrogen peroxide: a metabolic by-product or a common mediator of ageing signals?". Nat. Rev. Mol. Cell Biol. 8 (9): 722–8. doi:10.1038/nrm2240. PMID17700625.CS1 maint: Multiple names: authors list (link)
↑Rapoport, R.; Hanukoglu, I.; Sklan, D. (May 1994). "A fluorimetric assay for hydrogen peroxide, suitable for NAD(P)H-dependent superoxide generating redox systems". Anal Biochem. 218 (2): 309–13. doi:10.1006/abio.1994.1183. PMID8074285.
↑Tarr, edited by Matthew A. (2003). Chemical degradation methods for wastes and pollutants environmental and industrial applications. New York: M. Dekker. p. 165. ISBN9780203912553.CS1 maint: Extra text: authors list (link)
↑Pignatello, Joseph J.; Oliveros, Esther; MacKay, Allison (January 2006). "Advanced Oxidation Processes for Organic Contaminant Destruction Based on the Fenton Reaction and Related Chemistry". Critical Reviews in Environmental Science and Technology. 36 (1): 1–84. doi:10.1080/10643380500326564.
↑Pera-Titus, Marc; Garcı́a-Molina, Verónica; Baños, Miguel A; Giménez, Jaime; Esplugas, Santiago (February 2004). "Degradation of chlorophenols by means of advanced oxidation processes: a general review". Applied Catalysis B: Environmental. 47 (4): 219–256. doi:10.1016/j.apcatb.2003.09.010.
↑Goor, G.; Glenneberg, J.; Jacobi, S. (2007). "Hydrogen Peroxide". Ullmann's Encyclopedia of Industrial Chemistry. Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a13_443.pub2. ISBN3527306730.CS1 maint: Multiple names: authors list (link)
↑Ascenzi, edited by Joseph M. (1996). Handbook of disinfectants and antiseptics. New York: M. Dekker. p. 161. ISBN0824795245.CS1 maint: Extra text: authors list (link)
↑Rutala, W. A.; Weber, D. J. (1 September 2004). "Disinfection and Sterilization in Health Care Facilities: What Clinicians Need to Know". Clinical Infectious Diseases. 39 (5): 702–709. doi:10.1086/423182. PMID15356786.
↑Falagas, M.E.; Thomaidis, P.C.; Kotsantis, I.K.; Sgouros, K.; Samonis, G.; Karageorgopoulos, D.E. (July 2011). "Airborne hydrogen peroxide for disinfection of the hospital environment and infection control: a systematic review". Journal of Hospital Infection. 78 (3): 171–177. doi:10.1016/j.jhin.2010.12.006. PMID21392848.
↑Block, [edited by] Seymour S. (2000). "Chapter 9: Peroxygen compounds". Disinfection, sterilization, and preservation (5th ed.). Philadelphia: Lea & Febiger. pp. 185–204. ISBN0683307401.CS1 maint: Extra text: authors list (link)
↑Block, [edited by] Seymour S. (2000). "Chapter 27: Chemical Sporicidal and Sporostatic Agents". Disinfection, sterilization, and preservation (5th ed.). Philadelphia: Lea & Febiger. pp. 529–543. ISBN0683307401.CS1 maint: Extra text: authors list (link)
↑Loo, Alvin Eng Kiat; Wong, Yee Ting; Ho, Rongjian; Wasser, Martin; Du, Tiehua; Ng, Wee Thong; Halliwell, Barry; Sastre, Juan (13 November 2012). "Effects of Hydrogen Peroxide on Wound Healing in Mice in Relation to Oxidative Damage". PLoS ONE. 7 (11): e49215. Bibcode:2012PLoSO...749215L. doi:10.1371/journal.pone.0049215. PMID23152875.
↑Rahman, GA; Adigun, IA; Yusuf, IF; Ofoegbu, CKP (28 May 2010). "Wound dressing where there is limitation of choice". Nigerian Journal of Surgical Research. 8 (3–4). doi:10.4314/njsr.v8i3-4.54882.
↑Velding, K.; Klis, S.-A.; Abass, K. M.; Tuah, W.; Stienstra, Y.; van der Werf, T. (9 June 2014). "Wound Care in Buruli Ulcer Disease in Ghana and Benin". American Journal of Tropical Medicine and Hygiene. 91 (2): 313–318. doi:10.4269/ajtmh.13-0255. PMID24914002.
↑Capizzi, R.; Landi, F.; Milani, M.; Amerio, P. (2004). "Skin tolerability and efficacy of combination therapy with hydrogen peroxide stabilized cream and adapalene gel in comparison with benzoyl peroxide cream and adapalene gel in common acne. A randomized, investigator-masked, controlled trial". British Journal of Dermatology. 151 (2): 481–484. doi:10.1111/j.1365-2133.2004.06067.x. PMID15327558.
↑Douglass, William Campbell (1995). Hydrogen peroxide : medical miracle. [Atlanta, GA]: Second Opinion Pub. ISBN9781885236074.
↑Halliwell, Barry (1 January 2007). "Oxidative stress and cancer: have we moved forward?". Biochemical Journal. 401 (1): 1–11. doi:10.1042/BJ20061131. PMID17150040.
↑"Questionable methods of cancer management: hydrogen peroxide and other 'hyperoxygenation' therapies". CA: a cancer journal for clinicians. 43 (1): 47–56. 1993. doi:10.3322/canjclin.43.1.47. PMID8422605.
↑Scott, Richard (November 1997). "Homing Instincts". Jane's Navy Steam generated by catalytic decomposition of 80–90% hydrogen peroxide was used for driving the turbopump turbines of the V-2 rockets, the X-15 rocketplanes, the early Centaur RL-10 engines and is still used on Soyuz for that purpose to-day. International.
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