Chlorine trifluoride 1430901 223595477 2008-07-04T20:13:14Z DOI bot 6652755 Citation maintenance. Formatted: title. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{Chembox new | Name = Chlorine trifluoride | ImageFile = Chlorine-trifluoride.png | ImageFile1 = Chlorine-trifluoride-3D-vdW.png | Section1 = {{Chembox Identifiers | CASNo = 7790-91-2 | UNNumber = 1749 }} | Section2 = {{Chembox Properties | Formula = ClF<sub>3</sub> | MolarMass = 92.45 g/mol | Solvent = other solvents | SolubleOther = Hydrolysis | MeltingPt = -76.3 °C | BoilingPt = 11.75 °C }} | Section4 = {{Chembox Thermochemistry | DeltaHf = -158.87 kJ/mol | Entropy = 281.59 J.K<sup>&ndash;1</sup>.mol<sup>&ndash;1</sup> }} | Section7 = {{Chembox Hazards | MainHazards = Toxic, corrosive, oxidizer. | NFPA-H = 4 | NFPA-R = 3 | NFPA-O = OX, <s>W</s> }} | Section8 = {{Chembox Related | OtherCpds = [[Chlorine pentafluoride|ClF<sub>5</sub>]]<br />[[Chlorine monofluoride|ClF]]<br />[[Bromine trifluoride|BrF<sub>3</sub>]]}} }} '''Chlorine trifluoride''' is the [[chemical compound]] with the formula ClF<sub>3</sub>. This colourless, poisonous, corrosive and very reactive [[gas]] condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temperature). The compound is primarily of interest as a component in rocket fuels, in industrial cleaning and etching operations primarily in the semiconductor industry,<ref>{{cite journal | title = Silicon Etch Rate Using Chlorine Trifluoride | author = Hitoshi Habuka, Takahiro Sukenobu, Hideyuki Koda, Takashi Takeuchi, and Masahiko Aihara | journal = [[Journal of the Electrochemical Society]] | year = 2004 | volume = 151 | issue = 11 | pages = G783–G787 | doi = 10.1149/1.1806391 }} </ref><ref>[http://www.patentstorm.us/patents/5849092.html United States Patent 5849092 "Process for chlorine trifluoride chamber cleaning"]</ref> nuclear reactor fuel processing<ref>{{cite book | last = Board on Environmental Studies and Toxicology | first = (BEST) | title = Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 5 [http://books.nap.edu/catalog.php?record_id=11774 (citation at the National Academies Press)] | page = 40 | publisher = National Academies Press | date = 2006 | location = Washington D.C. | id= ISBN 0-309-10358-4 }}</ref> and other industrial operations.<ref>[http://www.patentstorm.us/patents/6034016-fulltext.html United States Patent 6034016 "Method for regenerating halogenated Lewis acid catalysts"]</ref> ==Preparation, structure, and properties== {{main|chlorine fluorides}} It was first reported by Ruff and Krug who prepared it by fluorination of [[chlorine]]; this also produced ClF and the mixture was separated by distillation.<ref>{{cite journal | title = Über ein neues Chlorfluorid-CIF<sub>3</sub> | author = [[Otto Ruff]], H. Krug | journal = [[Zeitschrift für anorganische und allgemeine Chemie]] | year = 1931 | volume = 190 | issue = 1 | pages = 602–608 | doi = 10.1002/zaac.19301900127 }} </ref> :3 F<sub>2</sub> + Cl<sub>2</sub> → 2 ClF<sub>3</sub> ClF<sub>3</sub> is approximately [[T-shaped (chemistry)|T-shaped]]. This structure is explicable in the context of [[VSEPR theory]], which considers also lone pairs of electrons as occupying two equatorial positions of a hypothetic trigonal bipyramid. The elongated Cl-F<sub>axial</sub> bonds are consistent with [[hypervalent bonding]]. Pure ClF<sub>3</sub> is stable to 180° in glass vessels, but above this temperature it decomposes by a [[free radical]] mechanism to the elements.<br /> The main use of ClF<sub>3</sub> is to produce [[uranium hexafluoride]], UF<sub>6</sub> as part of nuclear fuel processing and reprocessing, by the reaction: :U + 3ClF<sub>3</sub> <nowiki>&rarr;</nowiki>UF<sub>6</sub> + 3ClF ==Hazards== ClF<sub>3</sub> is a very strong [[Oxidizing agent|oxidizing]] and fluorination agent. ClF<sub>3</sub> is extremely reactive with most inorganic and organic materials and will initiate the combustion of many materials without an ignition source and these reactions are often violent or in some cases explosive. Several metals give [[chloride]]s and [[fluoride]]s, [[phosphorus]] yields PCl<sub>3</sub> plus PF<sub>5</sub>, [[sulfur]] SCl<sub>2</sub> plus SF<sub>4</sub>. ClF<sub>3</sub> is also violently water reactive in which it hydrolyses to a variety of hazardous chemicals such as [[hydrofluoric acid]]. [[Hydrogen sulfide|H<sub>2</sub>S]] explodes on being mixed with ClF<sub>3</sub> at room temperature. The ability to surpass the oxidizing ability of oxygen leads to corrosivity against oxide-containing materials often thought as incombustible. In an industrial accident, a spill of 900 kg of chlorine trifluoride burned itself through 30 cm of concrete and 90 cm of gravel beneath.<ref>Air Products Safetygram. http://www.airproducts.com/nr/rdonlyres/8479ed55-2170-4651-a3d4-223b2957a9f3/0/safetygram39.pdf</ref> Any equipment that comes into contact with chlorine trifluoride must be carefully selected and cleaned, because any contamination can ignite on contact. Exposure of larger amounts of chlorine trifluoride, as a liquid or as a gas, ignites tissue. The hydrolysis reaction with water is violent and exposure results in a thermal burn. The product of hydrolysis is [[hydrofluoric acid]], which is corrosive to human tissue, absorbs through skin, selectively attacks bone and stimulates pain nerves, and causes a potentially lethal poisoning. ==Military applications== Under the [[code name]] '''N-stoff''' ("substance N"), chlorine trifluoride was investigated for military applications by the [[Kaiser Wilhelm Institute]] in [[Nazi Germany]] from slightly before the start of [[World War II]]. Tests were made against mock-ups of the [[Maginot Line]] fortifications, and it was found to be an effective combined [[incendiary weapon]] and [[chemical warfare|poison gas]]. From 1938 construction commenced on a partly [[bunker]]ed, partly subterranean 31.76 km² munitions factory at [http://de.wikipedia.org/wiki/Bunker_Falkenhagen Falkenhagen] which was intended to produce 50 [[tonne]]s of N-stoff per month, plus [[Sarin]]. However by the time it was captured by the advancing [[Red Army]] in 1944, the factory had produced only about 30 to 50 tonnes, at a cost of over 100 [[German reichsmark|German Reichsmark]] per [[kilogram]]{{Fn|a}}. N-stoff was never used in war.<ref> [http://www.bunkertours.co.uk/germany_2004.htm "Bunker Tours" report on Falkenhagen]</ref> ==Rocket propellant== Chlorine trifluoride has been investigated as a high-performance storable oxidizer in [[rocket propellant]] systems. Handling concerns, however, prevented its use. [[John D. Clark|Clark]] summarized the difficulties, "It is, of course, extremely toxic, but that's the least of the problem. It is [[Hypergolic fuel|hypergolic]] with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water—with which it reacts explosively."<ref>{{cite book | author=Clark, John D. | title=Ignition! | publisher=UMI Books on Demand | year=2001 | id=ISBN 0-8135-0725-1}}</ref><ref>[http://www.astronautix.com/props/clfazine.htm ClF3/Hydrazine] at the Encyclopedia Astronautica.</ref> ==References== <div class="references-small"><references/> *{{cite book | last = Groehler | first = Olaf | title = Der lautlose Tod. Einsatz und Entwicklung deutscher Giftgase von 1914 bis 1945 | publisher = Rowohlt | date = 1989 | location = Reinbek bei Hamburg | id= ISBN 3-499-18738-8 }} *{{cite book | last = Ebbinghaus | first = Angelika | title = Krieg und Wirtschaft: Studien zur deutschen Wirtschaftsgeschichte 1939–1945 | publisher = Metropol | pages = 171–194 | date = 1999 | location = Berlin | id= ISBN 3-932482-11-5 }} *{{cite journal | title = The Halogen Fluorides | author = Harold Simmons Booth, John Turner Pinkston, , Jr. | journal = [[Chemical Reviews]] | year = 1947 | volume = 41 | issue = 3 | pages = 421–439 | doi = 10.1021/cr60130a001 }} *{{cite journal | title = Physicochemical Properties of Chlorine Trifluoride | author = Yu D Shishkov, A A Opalovskii | journal = [[Russian Chemical Reviews]] | year = 1960 | volume = 29 | issue = 6 | pages = 357–364 | doi = 10.1070/RC1960v029n06ABEH001237 }} *{{cite journal | title = The Structures of the Interhalogen Compounds. I. Chlorine Trifluoride at -120 °C | author = Robinson D. Burbank, Frank N. Bensey | journal = [[The Journal of Chemical Physics]] | year = 1953 | volume = 21 | issue = 4 | pages = 602–608 | doi = 10.1063/1.1698975 }} *{{cite journal | title = The determination of the liquid density of chlorine trifluoride | author = A. A. Banks and A. J. Rudge | journal = [[Journal of the Chemical Society]] | year = 1950 | volume = | issue = | pages = 191–193 | doi = 10.1039/JR9500000191 }} *{{cite journal | title = Pilot plant study of fluorine and its derivatives | author = Lowdermilk, F. R.; Danehower, R. G.; Miller, H. C. | journal = [[Journal of Chemical Education]] | year = 1951 | volume = 28 | issue = | pages = 246 | doi = }} </div> <small>{{Fnb|a}} Using data from [http://eh.net/hmit/exchangerates/ Economic History Services] and [http://www.westegg.com/inflation/infl.cgi The Inflation Calculator], we can calculate that 100 Reichsmark in 1941 is approximately equivalent to $540 US dollars in 2006. Reichsmark exchange rate values from 1942 to 1944 are fragmentary.</small> ==External links== *[http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory - Fluoride and compounds fact sheet] * [http://webbook.nist.gov/chemistry/ NIST Standard Reference Database] * [http://www.webelements.com/ WebElements] * [http://www.airproducts.com/nr/rdonlyres/8479ed55-2170-4651-a3d4-223b2957a9f3/0/safetygram39.pdf Safetygram #39 chemical profile] [[Category:Fluorides]] [[Category:Interhalogen compounds]] [[Category:Chlorine compounds]] [[Category:Incendiary weapons]] [[Category:Rocket oxidizers]] [[de:Chlor(III)-fluorid]] [[ja:三フッ化塩素]] [[pt:Trifluoreto de cloro]]