Potassium perchlorate is the inorganic salt with the chemical formula KClO4. Like other perchlorates, this salt is a strong 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, ammunitionpercussion caps, explosive primers, and is used variously in propellants, 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 It has been used as a solid rocket propellant, although in that application it has mostly been replaced by the more performant ammonium perchlorate.
KClO4 has a relatively low solubility in water (1.5 g in 100 mL of water at 25°C).[3]
Production
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 KClO4, which is about 1/100 as much as the solubility of NaClO4 (209.6 g/100 mL at 25°C).[8]
It can also be produced by bubbling chlorine gas through a solution of potassium chlorate and potassium hydroxide,[citation needed] 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 KClO4 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.
The conversion of solid glucose into hot gaseous CO2 is the basis of the explosive force of this and other such mixtures. With sugar, KClO4 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 firecrackers usually consist of a mixture of aluminium powder and potassium perchlorate. This mixture, sometimes called flash powder, is also used in ground and air fireworks.
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 kinetically poorer oxidants. Chlorate produces chloric acid (HClO3), which is highly unstable and can lead to premature ignition of the composition. Correspondingly, perchloric acid (HClO4) is quite stable.[9]
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 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).[10] 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.[11]
Treatment of thyrotoxicosis (including Graves' disease) with 600-2,000mg potassium perchlorate (430-1,400mg perchlorate) daily for periods of several months, or longer, was once a common practice, particularly in Europe,[10][12] and perchlorate use at lower doses to treat thyroid problems continues to this day.[13] Although 400mg of potassium perchlorate divided into four or five daily doses was used initially and found effective, higher doses were introduced when 400mg/d was discovered not to control thyrotoxicosis in all subjects.[10][11]
Current regimens for treatment of thyrotoxicosis (including Graves' disease), when a patient is exposed to additional sources of iodine, commonly include 500mg potassium perchlorate twice per day for 18–40 days.[10][14]
Prophylaxis with perchlorate-containing water at concentrations of 17 ppm, corresponding to 0.5mg/(kg·d) intake for a person of 70kg consuming 2 litres of water per day, was found to reduce the baseline of radioiodine uptake by 67%[10] This is equivalent to ingesting a total of just 35mg 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 10mg of perchlorate ions were ingested, an average 38% reduction in the uptake of Iodine was observed.[15]
However, when the average perchlorate absorption in perchlorate plant workers subjected to the highest exposure has been estimated as approximately 0.5mg/(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.[16] This may well be attributable to sufficient daily exposure, or intake, of stable iodine-127 among these workers and the short 8 hr biological half life of perchlorate in the body.[10]
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 0.5mg/(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 7.15mg/kg of body weight per day or a water concentration of 250 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,[10][14] 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.[17]
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.
Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. Some, however, use the terms interchangeably. Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, hand tremor, and weight loss. Symptoms are typically less severe in the elderly and during pregnancy. An uncommon but life-threatening complication is thyroid storm in which an event such as an infection results in worsening symptoms such as confusion and a high temperature; this often results in death. The opposite is hypothyroidism, when the thyroid gland does not make enough thyroid hormone.
Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at 114 °C (237 °F), and boils to a violet gas at 184 °C (363 °F). The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek Ιώδης, meaning 'violet'.
Tincture of iodine, iodine tincture, or weak iodine solution is an antiseptic. It is usually 2 to 3% elemental iodine, along with potassium iodide or sodium iodide, dissolved in a mixture of ethanol and water. Tincture solutions are characterized by the presence of alcohol. It was used from 1908 in pre-operative skin preparation by Italian surgeon Antonio Grossich.
A perchlorate is a chemical compound containing the perchlorate ion, ClO−4, the conjugate base of perchloric acid. As counterions, there can be metal cations, quaternary ammonium cations or other ions, for example, nitronium cation.
Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release of heat energy, and gamma rays. The two smaller nuclei are the fission products..
Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are used. In the third world it is also used for treating skin sporotrichosis and phycomycosis. It is a supplement used by people with low dietary intake of iodine. It is administered orally.
Lugol's iodine, also known as aqueous iodine and strong iodine solution, is a solution of potassium iodide with iodine in water. It is a medication and disinfectant used for a number of purposes. Taken by mouth it is used to treat thyrotoxicosis until surgery can be carried out, protect the thyroid gland from radioactive iodine, and to treat iodine deficiency. When applied to the cervix it is used to help in screening for cervical cancer. As a disinfectant it may be applied to small wounds such as a needle stick injury. A small amount may also be used for emergency disinfection of drinking water.
Iodine-131 is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nuclear energy, medical diagnostic and treatment procedures, and natural gas production. It also plays a major role as a radioactive isotope present in nuclear fission products, and was a significant contributor to the health hazards from open-air atomic bomb testing in the 1950s, and from the Chernobyl disaster, as well as being a large fraction of the contamination hazard in the first weeks in the Fukushima nuclear crisis. This is because 131I is a major fission product of uranium and plutonium, comprising nearly 3% of the total products of fission. See fission product yield for a comparison with other radioactive fission products. 131I is also a major fission product of uranium-233, produced from thorium.
Sodium perchlorate is an inorganic compound with the chemical formula NaClO4. It consists of sodium cations Na+ and perchlorate anions ClO−4. It is a white crystalline, hygroscopic solid that is highly soluble in water and ethanol. It is usually encountered as sodium perchlorate monohydrate NaClO4·H2O. The compound is noteworthy as the most water-soluble of the common perchlorate salts.
The Wolff–Chaikoff effect is a presumed reduction in thyroid hormone levels caused by ingestion of a large amount of iodine.
Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I−) in a crystal lattice. It is used mainly as a nutritional supplement and in organic chemistry. It is produced industrially as the salt formed when acidic iodides react with sodium hydroxide. It is a chaotropic salt.
There are 37 known isotopes of iodine (53I) from 108I to 144I; all undergo radioactive decay except 127I, which is stable. Iodine is thus a monoisotopic element.
The iodine clock reaction is a classical chemical clock demonstration experiment to display chemical kinetics in action; it was discovered by Hans Heinrich Landolt in 1886. The iodine clock reaction exists in several variations, which each involve iodine species and redox reagents in the presence of starch. Two colourless solutions are mixed and at first there is no visible reaction. After a short time delay, the liquid suddenly turns to a shade of dark blue due to the formation of a triiodide–starch complex. In some variations, the solution will repeatedly cycle from colorless to blue and back to colorless, until the reagents are depleted.
Goitrogens are substances that disrupt the production of thyroid hormones. This triggers the pituitary to release thyroid-stimulating hormone (TSH), which then promotes the growth of thyroid tissue, eventually leading to goiter.
Potassium iodate (KIO3) is an ionic inorganic compound with the formula KIO3. It is a white salt that is soluble in water.
An antithyroid agent is a hormone inhibitor acting upon thyroid hormones.
The radioactive iodine uptake test is a type of scan used in the diagnosis of thyroid problems, particularly hyperthyroidism. It is entirely different from radioactive iodine therapy, which uses much higher doses to destroy cancerous cells. The RAIU test is also used as a follow-up to RAI therapy to verify that no thyroid cells survived, which could still be cancerous.
Barium perchlorate is a powerful oxidizing agent, with the formula Ba(ClO4)2. It is used in the pyrotechnic industry.
Iodine is a chemical element with many uses in medicine, depending on the form. Elemental iodine and iodophors are topical antiseptics. Iodine, in non-elemental form, functions as an essential nutrient in human biology. Organic compounds containing iodine are also useful iodinated contrast agents in X-ray imaging.
The Plummer effect is one of several physiological feedforward mechanisms taking place in follicular cells of the healthy thyroid gland and preventing the development of thyrotoxicosis in situations of extremely high supply with iodine.
1 2 Potassium perchlorate in Linstrom, PeterJ.; Mallard, WilliamG. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 2014-05-27)
↑ Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p.A22. ISBN978-0-618-94690-7.
↑ 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
↑ Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN0-7506-3365-4.
1 2 Wolff, J (1998). "Perchlorate and the thyroid gland". Pharmacological Reviews. 50 (1): 89–105. PMID9549759.
↑ Barzilai, D; Sheinfeld, M (1966). "Fatal complications following use of potassium perchlorate in thyrotoxicosis. Report of two cases and a review of the literature". Israel Journal of Medical Sciences. 2 (4): 453–6. PMID4290684.
↑ Woenckhaus, U.; Girlich, C. (2005). "Therapie und Prävention der Hyperthyreose" [Therapy and prevention of hyperthyroidism]. Der Internist (in German). 46 (12): 1318–23. doi:10.1007/s00108-005-1508-4. PMID16231171.
↑ Lawrence, J. E.; Lamm, S. H.; Pino, S.; Richman, K.; Braverman, L. E. (2000). "The Effect of Short-Term Low-Dose Perchlorate on Various Aspects of Thyroid Function". Thyroid. 10 (8): 659–63. doi:10.1089/10507250050137734. PMID11014310.
↑ Lamm, Steven H.; Braverman, Lewis E.; Li, Feng Xiao; Richman, Kent; Pino, Sam; Howearth, Gregory (1999). "Thyroid Health Status of Ammonium Perchlorate Workers: A Cross-Sectional Occupational Health Study". Journal of Occupational & Environmental Medicine. 41 (4): 248–60. doi:10.1097/00043764-199904000-00006. PMID10224590.
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