Editing Potassium perchlorate

{{Chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 461740157
| ImageFile = Potassium perchlorate.png
| ImageSize = 200px
| ImageFileL1 = Potassium-perchlorate-unit-cell-3D-balls-perspective.png
| ImageSizeL1 = 
| ImageFileR1 = Potassium-perchlorate-xtal-3D-SF.png
| ImageSizeR1 = 
| ImageFile2 = Potassium perchlorate 200g.jpg
| ImageSize2 = 200px
| Name = Potassium perchlorate
| OtherNames = Potassium chlorate(VII); Perchloric acid, potassium salt; peroidin
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 22913
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 1200696
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 42255P5X4D
| InChI = 1/ClHO4.K/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1
| InChIKey = YLMGFJXSLBMXHK-REWHXWOFAB
| SMILES = [K+].[O-]Cl(=O)(=O)=O
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/ClHO4.K/c2-1(3,4)5;/h(H,2,3,4,5);/q;+1/p-1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = YLMGFJXSLBMXHK-UHFFFAOYSA-M
| CASNo = 7778-74-7
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 516900
| EINECS = 231-912-9
| RTECS = SC9700000
| UNNumber = 1489
  }}
|Section2={{Chembox Properties
| Formula = KClO<sub>4</sub>
| MolarMass = 138.55 g/mol
| Appearance = colourless/ white crystalline powder
| Density = 2.5239 g/cm<sup>3</sup>
| MeltingPtC = 610
| MeltingPt_notes = <br> decomposes from 400 °C<ref name="hop">{{cite book|last1 = Benenson|first1 = Walter|last2 = Stöcker|first2 = Horst|title = Handbook of Physics| date=13 January 2006 |publisher = Springer|page = [https://archive.org/details/handbookofphysic0000harr/page/780 780]|isbn = 978-0387952697|url = https://archive.org/details/handbookofphysic0000harr/page/780}}</ref><ref name="sigma" />
| Solubility = 0.76 g/100 mL (0 °C)<br> 1.5 g/100 mL (25 °C)<ref name = "jtbaker">{{cite web|url=http://hazard.com/msds/mf/baker/baker/files/p5983.htm|publisher=[[J.T. Baker]]|title = Potassium Perchlorate MSDS|date=2007-02-16|access-date=2007-12-10}}</ref><br> 4.76 g/100 mL (40 °C)<br> 21.08 g/100 mL (100 °C)<ref name=chemister>{{cite web|url=http://chemister.ru/Database/properties-en.php?dbid=1&id=519|title=potassium perchlorate|website=chemister.ru|access-date=14 April 2018}}</ref>
| SolubleOther = negligible in [[ethanol|alcohol]]<br>  insoluble in [[diethyl ether|ether]]
| Solubility1 = 47 mg/kg (0 °C)<br> 120 mg/kg (25 °C)<ref name = chemister />
| Solvent1 = ethanol
| Solubility2 = 1.6 g/kg<ref name = chemister />
| Solvent2 = acetone
| Solubility3 = 15 mg/kg<ref name = chemister />
| Solvent3 = ethyl acetate
| RefractIndex = 1.4724
| SolubilityProduct = 1.05·10<sup>−2</sup><ref>{{Cite web | url=http://www.solubilityofthings.com/water/ions_solubility/ksp_chart.php | title=Ksp solubility product constants of many popular salts at SolubilityOFthings}}</ref>
  }}
|Section3={{Chembox Structure
| Coordination = 
| CrystalStruct = Rhombohedral
  }}
|Section4={{Chembox Thermochemistry
| DeltaHf = −433 kJ/mol<ref name=b1>{{cite book|author=Zumdahl, Steven S.|title=Chemical Principles 6th Ed.|publisher=Houghton Mifflin Company|year=2009|isbn=978-0-618-94690-7|page=A22}}</ref>
| HeatCapacity = 111.35 J/mol·K<ref name=nist>{{nist|name=Potassium perchlorate|id=C7778747|accessdate=2014-05-27|mask=FFFF|units=SI}}</ref>
| DeltaGf = −300.4 kJ/mol<ref name = chemister />
| Entropy = 150.86 J/mol·K<ref name=nist />
 }}
|Section7={{Chembox Hazards
| ExternalSDS = [http://physchem.ox.ac.uk/MSDS/PO/potassium_perchlorate.html MSDS]
| GHSPictograms = {{GHS03}}{{GHS07}}<ref name="sigma">[[Sigma-Aldrich|Sigma-Aldrich Co.]], [https://www.sigmaaldrich.com/US/en/product/sigald/241830 Potassium perchlorate]. Retrieved on 2022-02-17.</ref>
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|271|302|335|}}<ref name="sigma" />
| PPhrases = {{P-phrases|220|280}}<ref name="sigma" />
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 1
| NFPA-S = OX
| FlashPt =
  }}
|Section8={{Chembox Related
| OtherAnions = [[Potassium chloride]]<br> [[Potassium chlorate]]<br> [[Potassium periodate]]
| OtherCations = [[Ammonium perchlorate]]<br> [[Sodium perchlorate]]
  }}
}}

'''Potassium perchlorate''' is the inorganic [[salt (chemistry)|salt]] with the chemical formula [[potassium|K]][[chlorine|Cl]][[oxygen|O<sub>4</sub>]]. Like other [[perchlorate]]s, this salt is a strong [[oxidizing agent|oxidizer]] when the solid is heated at high temperature although it usually reacts very slowly in solution with reducing agents or organic substances. This colorless crystalline solid is a common oxidizer used in [[fireworks]], [[ammunition]] [[percussion cap]]s, and [[explosive primer]]s, and is used variously in [[propellant]]s, [[flash powder|flash compositions]], stars, and [[sparklers]]. It has been used as a [[solid rocket]] propellant, although in that application it has mostly been replaced by the more performant [[ammonium perchlorate]].

KClO<sub>4</sub> has a relatively low [[solubility]] in water (1.5&nbsp;g in 100&nbsp;mL of water at 25&nbsp;°C).<ref name="jtbaker" />

==Production==
[[File:Perclorato de Potássio.jpg|200px|thumbnail|left|Potassium perchlorate in crystal form]]
Potassium perchlorate is prepared industrially by treating an aqueous solution of [[sodium perchlorate]] with [[potassium chloride]]. This single precipitation reaction exploits the low [[solubility]] of KClO<sub>4</sub>, which is about 1/100 as much as the solubility of NaClO<sub>4</sub> (209.6 g/100 mL at 25&nbsp;°C).<ref>Helmut Vogt, Jan Balej, John E. Bennett, Peter Wintzer, Saeed Akbar Sheikh, Patrizio Gallone "Chlorine Oxides and Chlorine Oxygen Acids" in ''Ullmann's Encyclopedia of Industrial Chemistry'' 2002, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a06_483}}</ref>

It can also be produced by bubbling chlorine gas through a solution of [[potassium chlorate]] and [[potassium hydroxide]],{{citation needed|date=June 2017}} and by the reaction of [[perchloric acid]] with potassium hydroxide; however, this is not used widely due to the dangers of perchloric acid.

Another preparation involves the [[electrolysis]] of a potassium chlorate solution, causing KClO<sub>4</sub> to form and precipitate at the [[anode]]. This procedure is complicated by the low solubility of both potassium chlorate and potassium perchlorate, the latter of which may precipitate onto the electrodes and impede the current.

==Oxidizing properties==
KClO<sub>4</sub> is an [[Oxidizing agent|oxidizer]] in the sense that it exothermically ''"transfers [[oxygen]]"'' to [[combustible]] materials, greatly increasing their rate of [[combustion]] relative to that in [[air]]. Thus, it reacts with [[glucose]] to give [[carbon dioxide]], water molecules and [[potassium chloride]]:

: 3 KClO<sub>4</sub>  +  C<sub>6</sub>H<sub>12</sub>O<sub>6</sub>   →   6 CO<sub>2</sub>  +  6 H<sub>2</sub>O  +  3 KCl

The conversion of solid glucose into hot gaseous {{CO2}} is the basis of the explosive force of this and other such mixtures. With [[Sucrose|sugar]], KClO<sub>4</sub> yields a low explosive, provided a necessary confinement. Otherwise such mixtures simply [[deflagrate]] with an intense purple flame characteristic of [[potassium]]. Flash compositions used in [[firecracker]]s usually consist of a mixture of [[aluminium]] powder and potassium perchlorate. This mixture, sometimes called flash powder, is also used in ground and air [[firework]]s.

As an oxidizer, potassium perchlorate can be used safely in the presence of [[sulfur]], whereas [[potassium chlorate]] cannot. The greater reactivity of chlorate is typical – perchlorates are [[Chemical kinetics|kinetically]] poorer oxidants. [[Chlorate]] produces [[chloric acid]] ({{Chem2|HClO3}}), which is highly unstable and can lead to premature ignition of the composition. Correspondingly, [[perchloric acid]] ({{Chem2|HClO4}}) is quite stable.<ref>Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. {{ISBN|0-7506-3365-4}}.</ref>

For a commercial use, potassium perchlorate is mixed 50/50 with [[potassium nitrate]] to fabricate ''Pyrodex'', a [[black powder substitute]], and when not compressed within a muzzle loading firearm or in a cartridge, burns at a sufficiently slow rate to prevent it from being categorized with the [[black powder]] as a "low explosive", and to demote it as "flammable" material.

==Debated medical use==
Potassium perchlorate can be used as an [[antithyroid]] agent used to treat [[hyperthyroidism]], usually in combination with one other medication.  This application exploits the similar [[ionic radius]] and [[Hydrophile|hydrophilicity]] of perchlorate and [[iodide]].

The administration of known [[goitrogen]] substances can also be used as a prevention in reducing the biological uptake of [[iodine]], (whether it is the nutritional non-radioactive [[iodine-127]] or radioactive iodine, most commonly [[iodine-131]] ([[half-life]] = 8.02 days), as the body cannot discern between different iodine [[isotopes]]). [[Perchlorate]] ions, a common water contaminant in the USA due to the [[aerospace industry]], has been shown to reduce iodine uptake and thus is classified as a [[goitrogen]]. Perchlorate ion is a competitive inhibitor of the process by which iodide is actively accumulated into the thyroid follicular cells. Studies involving healthy adult volunteers determined that at levels above 7 micrograms per kilogram per day (μg/(kg·d)), perchlorate begins to temporarily inhibit the thyroid gland's ability to absorb iodine from the bloodstream ("iodide uptake inhibition", thus perchlorate is a known goitrogen).<ref name="bare_url">{{cite journal |doi=10.1289/ehp.02110927 |title=Health Effects Assessment for Environmental Perchlorate Contamination: The Dose Response for Inhibition of Thyroidal Radioiodine Uptake in Humans |year=2002 |last1=Greer |first1=Monte A. |last2=Goodman |first2=Gay |last3=Pleus |first3=Richard C. |last4=Greer |first4=Susan E. |journal=Environmental Health Perspectives |volume=110 |issue=9 |pages=927–37 |pmid=12204829 |pmc=1240994}}</ref> The reduction of the iodide pool by perchlorate has a dual effect – reduction of excess [[hormone]] synthesis and [[hyperthyroidism]], on the one hand, and reduction of thyroid inhibitor synthesis and [[hypothyroidism]] on the other. Perchlorate remains very useful as a single dose application in tests measuring the discharge of radioiodide accumulated in the thyroid as a result of many different disruptions in the further metabolism of iodide in the thyroid gland.<ref name="ncbi">{{cite journal |pmid=9549759 |year=1998 |last1=Wolff |first1=J |title=Perchlorate and the thyroid gland |volume=50 |issue=1 |pages=89–105 |journal=Pharmacological Reviews}}</ref>

Treatment of [[Hyperthyroidism|thyrotoxicosis]] (including [[Graves' disease]]) with 600-2,000&nbsp;mg potassium perchlorate (430-1,400&nbsp;mg perchlorate) daily for periods of several months, or longer, was once a common practice, particularly in Europe,<ref name="bare_url" /><ref>{{cite journal |pmid=4290684 |year=1966 |last1=Barzilai |first1=D |last2=Sheinfeld |first2=M |title=Fatal complications following use of potassium perchlorate in thyrotoxicosis. Report of two cases and a review of the literature |volume=2 |issue=4 |pages=453–6 |journal=Israel Journal of Medical Sciences}}</ref> and perchlorate use at lower doses to treat thyroid problems continues to this day.<ref>{{cite journal |doi=10.1007/s00108-005-1508-4 |title=Therapie und Prävention der Hyperthyreose |trans-title=Therapy and prevention of hyperthyroidism |language=de |year=2005 |last1=Woenckhaus |first1=U. |last2=Girlich |first2=C. |journal=Der Internist |volume=46 |issue=12 |pages=1318–23 |pmid=16231171}}</ref> Although 400&nbsp;mg of potassium perchlorate divided into four or five daily doses was used initially and found effective, higher doses were introduced when 400&nbsp;mg/d was discovered not to control thyrotoxicosis in all subjects.<ref name="bare_url" /><ref name="ncbi" />

Current regimens for treatment of [[thyrotoxicosis]] (including Graves' disease), when a patient is exposed to additional sources of iodine, commonly include 500&nbsp;mg potassium perchlorate twice per day for 18–40 days.<ref name="bare_url" /><ref name="ncbi_a">{{cite journal |title=Treatment of amiodarone-induced thyrotoxicosis, a difficult challenge: Results of a prospective study |year=1996 |last1=Bartalena |first1=L. |journal=Journal of Clinical Endocrinology & Metabolism |volume=81 |issue=8 |pmid=8768854 |pages=2930–3 |last2=Brogioni |first2=S |last3=Grasso |first3=L |last4=Bogazzi |first4=F |last5=Burelli |first5=A |last6=Martino |first6=E|doi=10.1210/jcem.81.8.8768854 |doi-access=free }}</ref>

[[Preventive healthcare|Prophylaxis]] with perchlorate-containing water at concentrations of 17 [[Parts per million|ppm]], corresponding to 0.5&nbsp;mg/(kg·d) intake for a person of 70&nbsp;kg consuming 2 litres of water per day, was found to reduce the baseline of radioiodine uptake by 67%<ref name="bare_url" /> This is equivalent to ingesting a total of just 35&nbsp;mg of perchlorate ions per day. In another related study were subjects drank just 1 litre of perchlorate-containing water per day at a concentration of 10 ppm, i.e. daily 10&nbsp;mg of perchlorate ions  were ingested, an average 38% reduction in the uptake of Iodine was observed.<ref>{{cite journal |doi=10.1089/10507250050137734 |title=The Effect of Short-Term Low-Dose Perchlorate on Various Aspects of Thyroid Function |year=2000 |last1=Lawrence |first1=J. E. |last2=Lamm |first2=S. H. |last3=Pino |first3=S. |last4=Richman |first4=K. |last5=Braverman |first5=L. E. |journal=Thyroid |volume=10 |issue=8 |pages=659–63 |pmid=11014310}}</ref>

However, when the average perchlorate absorption in perchlorate plant workers subjected to the highest exposure has been estimated as approximately 0.5&nbsp;mg/(kg·d), as in the above paragraph, a 67% reduction of iodine uptake would be expected. Studies of chronically exposed workers though have thus far failed to detect any abnormalities of thyroid function, including the uptake of iodine.<ref>{{cite journal |doi=10.1097/00043764-199904000-00006 |title=Thyroid Health Status of Ammonium Perchlorate Workers: A Cross-Sectional Occupational Health Study |year=1999 |last1=Lamm |first1=Steven H. |last2=Braverman |first2=Lewis E. |last3=Li |first3=Feng Xiao |last4=Richman |first4=Kent |last5=Pino |first5=Sam |last6=Howearth |first6=Gregory |journal=Journal of Occupational & Environmental Medicine |volume=41 |issue=4 |pmid=10224590 |pages=248–60}}</ref> This may well be attributable to sufficient daily exposure, or intake, of stable [[Isotopes of iodine|iodine-127]] among these workers and the short 8 hr [[biological half life]] of perchlorate in the body.<ref name="bare_url" />

To completely block the uptake of iodine-131 (half-life = 8.02 days) by the purposeful addition of perchlorate ions to a public water supply, aiming at dosages of 0.5&nbsp;mg/(kg·d), or a water concentration of 17 ppm, would therefore be grossly inadequate at truly reducing a radio-iodine uptake. Perchlorate ion concentrations in a region water supply, would need to be much higher, at least 7.15&nbsp;mg/kg of body weight per day or a water concentration of 250 [[Parts per million|ppm]], assuming people drink 2 liters of water per day, to be truly beneficial to the population at preventing [[bioaccumulation]] when exposed to an iodine-131 contamination,<ref name="bare_url" /><ref name="ncbi_a" /> independent of the availability of [[iodate]] or [[iodide]] compounds.

The distribution of perchlorate tablets, or the addition of perchlorate to the water supply, would need to continue for 80–90 days (~10 half-life of 8.02 days) after the release of iodine-131. After this time, the radioactive iodine-131 would have decayed to less than 1/1000 of its initial activity at which time the danger from the biological uptake of iodine-131 is essentially over.<ref>{{cite web|url=http://www.dummies.com/how-to/content/nuclear-chemistry-halflives-and-radioactive-dating.html |title=Nuclear Chemistry: Half-Lives and Radioactive Dating - For Dummies |publisher=Dummies.com |date=2010-01-06 |access-date=2013-01-21}}</ref>

===Limitations and criticisms===
So, perchlorate administration could represent a possible alternative to iodide tablets distribution in case of a large-scale nuclear accident releasing important quantities of iodine-131 in the atmosphere. However, the advantages are not always clear and would depend on the extent of a hypothetical nuclear accident. As for the stable iodide intake to rapidly saturate the thyroid gland before it accumulates radioactive iodine-131, a careful cost-benefit analysis has to be first done by the nuclear safety authorities. Indeed, blocking the thyroid activity of a whole population for three months can also have negative consequences for the human health, especially for young children. 

So, the decision of perchlorate, or stable iodine, administration cannot be left to the individual initiative and falls under the authority of the government in case of a major nuclear accident. 

Injecting perchlorate or iodide directly in the public drinking water is also probably as restrictive as tablets distribution.

==See also==
* [[Chlorate]]
* [[Iodide]]

==References==
{{Reflist}}

== Further reading ==
*{{Cite encyclopedia |title=Perchlorate Oxidizers |encyclopedia=Encyclopedia of Oxidizers |publisher=De Gruyter |last=Schmidt |first=Eckart W.  |date=2022 |pages=3752–3761|doi=10.1515/9783110750294-028 |isbn=978-3-11-075029-4 |chapter=Alkali Metal Chlorates and Perchlorates}}
==External links==
{{Commons category|Potassium perchlorate}}
* [https://webbook.nist.gov/cgi/cbook.cgi?ID=C7778747 WebBook page for KClO<sub>4</sub>]

{{Potassium compounds}}
{{Perchlorates}}
{{Thyroid therapy}}
{{Thyroid hormone receptor modulators}}

[[Category:Potassium compounds]]
[[Category:Perchlorates]]
[[Category:Pyrotechnic oxidizers]]