Sulfur mustard
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2008-07-10T19:56:11Z
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{{Chembox new
| Name = Sulfur mustard
| ImageFile = Sulfur-mustard-2D-skeletal.png
| ImageFile1 = Sulfur-mustard-3D-balls.png
| ImageFile2 = Sulfur-mustard-3D-vdW.png
| IUPACName = Bis(2-chloroethyl) sulfide
| OtherNames = Iprit; Kampfstoff "Lost"; Lost; Mustard gas; Senfgas; Yellow Cross Liquid; Yperite; Distilled Mustard; Mustard T- mixture
| Section2 = {{Chembox Properties
| Formula = C<sub>4</sub>H<sub>8</sub>Cl<sub>2</sub>S
| MolarMass = 159 g/mol
| Appearance = Colorless if pure.<br/>Normally ranges from<br />pale yellow to dark brown.<br/>Slight garlic or horseradish type odor<ref name="FM 3-8">'''FM 3-8 Chemical Reference handbook'''; US Army; 1967</ref>
| Density = 1.27 g/ml, liquid
| Solubility = Negligible
| MeltingPt = 14.4 °C
| BoilingPt = 217 °C (decomposes)
}}| Section7 = {{Chembox Hazards
| ExternalMSDS = [http://www.gulfweb.org/bigdoc/report/apphd.html#General%20Information External MSDS]
| MainHazards = [[Vesicant]]
| NFPA-H = 4
| NFPA-F = 1
| NFPA-R = 1
| FlashPt = 105 °C
}}
| Section8 = {{Chembox Related
| OtherCpds = [[Nitrogen mustard]]
}}
}}
The '''sulfur mustards''', of which '''mustard gas''' ([[bis]](2-chloroethyl) sulfide) is a member, are a class of related [[cytotoxic]], [[vesicant]] [[chemical warfare agent]]s with the ability to form large [[blister]]s on exposed skin. In their pure form most sulfur mustards are colorless, odorless, viscous liquids at room temperature. When used in impure form as warfare agents they are usually yellow-brown in color and have an odor resembling [[mustard plant]]s, [[garlic]] or [[horseradish]], hence the innocuous name. The name originally assigned by the German Empire was "Lost", after the individuals Lommel and Steinkopf who first proposed the military use of Sulfur Mustard to the German Imperial General Staff.
Mustard agents are regulated under the 1993 [[Chemical Weapons Convention]] (CWC). Three classes of chemicals are monitored under this Convention, with sulfur and nitrogen mustard grouped in [[List of Schedule 1 substances (CWC)|Schedule 1]], as substances with no use other than chemical warfare.
==Formulations==
In its history, several varieties and mixtures of sulfur mustard have been employed. Some of those varieties are listed below:
* '''H''' – Also known as '''HS''' ("Hun Stuff") or ''Levinstein mustard''. Manufactured by reacting dry [[ethylene]] with [[disulfur dichloride|sulfur monochloride]] under controlled conditions. Undistilled sulfur mustard contains 20–30% impurities, for which reason it does not store as well as '''HD'''. Also, as it decomposes, it increases in vapor pressure, making the munition it is contained in likely to split, especially along a seam, thus releasing the agent to the atmosphere<ref name="FM 3-8" />
* '''HD''' – Codenamed '''Pyro''' by the British, and '''Distilled Mustard''' by the US<ref name="FM 3-8" />. [[distillation|Distilled]] sulfur mustard (bis(2-chloroethyl) sulfide); approximately 96% pure. The term "mustard gas" usually refers to this variety of sulfur mustard. A much used path of synthesis was based upon the reaction of [[thiodiglycol]] with [[hydrochloric acid]].
* '''HT''' – Codenamed '''Runcol''' by the British, and '''Mustard T- mixture''' by the US<ref name="FM 3-8" />. A mixture of 60% sulfur mustard (HD) and 40% T ([[bis[2-(2-chloroethylthio)ethyl] ether]], a related vesicant with lower [[freezing point]] lower [[Volatility (chemistry)|volatility]] and similar vesicant characteristics).
* '''HL''' – A blend of distilled mustard (HD) and [[lewisite]] (L), originally intended for use in winter conditions due to its lower freezing point compared to the pure substances.
* '''HQ''' – A blend of distilled mustard (HD) and sesquimustard (Q) (Gates and Moore 1946).
==Chemistry==
Mustard gas is the [[organic compound]] described with the [[chemical formula|formula]] (ClCH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>S. It has several names (see table). In the Depretz method, mustard gas is synthesized by treating [[sulfur dichloride]] with [[ethylene]]:
:SCl<sub>2</sub> + 2 C<sub>2</sub>H<sub>4</sub> → (ClCH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>S
In the Meyer method, [[thiodiglycol]] is produced from [[chloroethanol]] and [[potassium sulfide]] and chlorinated with [[phosphorus trichloride]]:<ref>{{cite web|url=http://books.nap.edu/openbook.php?record_id=2058&page=71|title=Chapter 5: Chemistry of Sulfur Mustard and Lewisite|author=Institute of Medicine |date=1993 |work=Veterans at Risk: The Health Effects of Mustard Gas and Lewisite |publisher=The National Academies Press}}</ref>
:3(HO-CH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>S + 2PCl<sub>3</sub> → 3(Cl-CH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>S + 2P(OH)<sub>3</sub>
In the Meyer-Clarke method, concentrated [[hydrochloric acid]] (HCl) instead of PCl<sub>3</sub> is used as the chlorinating agent:
:(HO-CH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>S + 2HCl → (Cl-CH<sub>2</sub>CH<sub>2</sub>)<sub>2</sub>S + 2H<sub>2</sub>O
[[Thionyl chloride]] and [[phosgene]] have also been used as chlorinating agents.
Although the compound is commonly known as "mustard gas", it is a viscous liquid at normal temperatures. The pure compound has a melting point of 14°C (57°F) and decomposes before boiling at 218 °C (423 °F).
[[Image:Mustard-dna.png]]
The compound readily eliminates [[chloride]] ion by intramolecular [[nucleophilic substitution]] to form a cyclic [[sulfonium]] ion. This very reactive intermediate tends to bond to the [[guanine]] [[nucleotide]] in [[DNA]] strands, which is particularly detrimental to cellular health. This alkylation leads to either [[cellular death]] or [[cancer]]. Mustard gas is not very soluble in water but is very soluble in fat, contributing to its rapid absorption into the skin.
In the wider sense, compounds with the structural element BCH<sub>2</sub>CH<sub>2</sub>X, where ''B'' is any [[leaving group]] and ''X'' is a [[Lewis base]] are known as ''mustards''. Such compounds can form cyclic "onium" ions ([[sulfonium]], [[ammonium]]s, etc.) that are good [[alkylating agent]]s. Examples are bis(2-chloroethyl)ether, the (2-haloethyl)amines ([[nitrogen mustard]]s), and sulfur sesquimustard, which has two α-chloroethyl thioether groups (ClH<sub>2</sub>C-CH<sub>2</sub>-S-) connected by an ethylene (-CH<sub>2</sub>CH<sub>2</sub>-) group. These compounds have a similar ability to alkylate DNA, but their physical properties, e.g. melting point, vary.
==History==
===Development===
Mustard gas was possibly developed as early as 1822 by M. Depretz (1798–1863). Depretz described the reaction of [[sulfur dichloride]] and [[ethene]] but never made mention of any irritating properties of the reaction product which makes the claim doubtful. In 1854, another French chemist [[Alfred Riche]] (1829–1908) repeated the procedure but again did not describe any adverse physiological properties. In 1886, chemist [[Albert Niemann (chemist)|Albert Niemann]], known as a pioneer in [[cocaine]] chemistry, repeated the reaction but this time blister forming properties were recorded. In 1860, [[Frederick Guthrie]] synthesised and characterized the compound, and he also noted its irritating properties especially in tasting. In 1886, [[Viktor Meyer]] published a paper describing a synthesis which produced good yields. He reacted [[2-Chloroethanol|2-chloroethanol]] with [[aqueous]] [[potassium sulfide]] and treated the resulting thiodiglycol with [[phosphorus trichloride]]. The purity of this compound was much higher and the adverse health effects on exposure consequently much more severe. These symptoms presented themselves in an assistant, and in order to rule out that the assistant was suffering from a mental illness (faking the symptoms) Meyer had the compound tested on rabbits, which consequently died. In 1913, English chemist [[Hans T. Clarke]] (of [[Eschweiler-Clarke reaction|Eschweiler-Clarke]] fame) replaced phosphorus trichloride by [[hydrochloric acid]] in Meyers recipe while working with [[Emil Fischer]] in [[Berlin]]. Clarke was hospitalized for 2 months for burns after a flask broke, and according to him Fisher's subsequent report on this incident to the [[German Chemical Society]] set Germany on the chemical weapons track<ref>''Mustard Gas: Its Pre-World War I History'' Duchovic, Ronald J.; Vilensky, Joel A. J. Chem. Educ. '''2007''', 84, 944. Mustard gas can have the problem of turning a patient's skin a different color, including red, orange, pink, and in rare cases, blue.[http://jchemed.chem.wisc.edu/Journal/Issues/2007/Jun/abs944.html Link]</ref>. [[Germany]] in [[World War I]] relied on the Meyer-Clarke method with a [[2-Chloroethanol|2-chloroethanol]] infrastructure already in place in the dye industry of that time.
===Use===
Mustard gas was first [[Use of poison gas in World War I|used effectively in World War I]] by the German army against British soldiers near Ypres in July 1917 and later also against the [[France|French]] Second Army. The name '''''Yperite''''' comes from its usage by the German army near the city of [[Ypres]]. The Allies did not use mustard until November 1917 at Cambrai, after they captured a large stock of German mustard-filled shells. It took the British over a year to develop their own mustard gas weapon (their only option was the Despretz–Niemann–Guthrie process), first using it in September 1918 during the breaking of the [[Hindenburg Line]].
Mustard gas was dispersed as an [[Particulate|aerosol]] in a mixture with other chemicals, giving it a yellow-brown color and a distinctive odor. Mustard gas has also been dispersed in such munitions as aerial bombs, land mines, mortar rounds, [[howitzer]] rounds, and rockets<ref name="FM 3-8" />. Mustard gas was lethal in only about 1% of cases; its effectiveness was as an incapacitating agent. Countermeasures against the gas were relatively ineffective, since a soldier wearing a [[gas mask]] was not protected against absorbing it through the skin.
Furthermore, mustard gas was a persistent agent which would remain in the environment for days and continue to cause sickness. If mustard gas contaminated a soldier's clothing and equipment, then other soldiers he came into contact with would also be poisoned. Towards the end of the war it was even used in high concentrations as an [[Area denial weapons|area-denial weapon]], which often forced soldiers to abandon heavily contaminated positions.
Since then, mustard gas has also been reportedly used in several wars, often where those it is used against cannot retaliate:<ref name="CBWInfo">[http://www.cbwinfo.com/Chemical/Blister/HD.shtml Blister Agent: Sulfur Mustard (H, HD, HS)], CBWinfo.com</ref>
* [[United Kingdom]] against the [[Red Army]] in 1919;<ref name="fas">[http://www.fas.org/bwc/papers/review/cwtable.htm Uses of CW since the First World War], Federation of American Scientists</ref>
* [[Spain]] against [[Rif]] insurgents in [[Morocco]] in 1921-1927;<ref name="CBWInfo" /><ref name="GCSY">{{cite book |chapter = Global society and biological and chemical weapons |author = Daniel Feakes |editors = Mary Kaldor, Helmut Anheier and Marlies Glasius |title = Global Civil Society Yearbook 2003 |publisher = Oxford University Press |year=2003 |pages= 87-117 |url = http://www.sussex.ac.uk/Units/spru/hsp/Feakes%20chapter.pdf }}</ref>
* [[Italy]] in [[Libya]] in [[1930]];<ref name="CBWInfo" />
* [[Soviet Union]] in [[Xinjiang]], [[China]] in [[1934]] and 1936-1937;<ref name="fas" /><ref name="GCSY" />
* [[Italy]] in Abyssinia (now [[Ethiopia]]) in 1935-1940;<ref name="CBWInfo" />
* [[Poland]] against [[Germany]] in [[1939]] during an isolated incident, British product;<ref name="CBWInfo" />
* Germany against Poland and the Soviet Union in a few erroneous uses during the [[Second World War]];<ref name="CBWInfo" />
* [[Japan]] against [[China]] in 1937-1945;<ref name="fas" />
* [[Egypt]] against [[North Yemen]] in 1963-1967;<ref name="CBWInfo" />
* [[Iraq]] against [[Iran]] in 1983-1988; <ref name="fas"/><ref name="Reuters">[http://www.reuters.com/article/topNews/idUSBLA84491620080709?feedType=RSS&feedName=topNews&rpc=22&sp=true], Reuters</ref>
* Possibly [[Sudan]] against insurgents in the civil war, in 1995 and 1997<ref name="CBWInfo" />
In 1943, during the Second World War, a [[United States|U.S.]] stockpile exploded aboard a supply ship that was bombed in the harbor of [[Bari]], [[Italy]], exposing and killing thousands of civilians and 628 Allied troops. The deaths and incident were classified Top Secret for 55 years and labeled as a mystery illness. It was noted by the U.S. Army's medical workers that the white cell counts of exposed soldiers were reduced, and mustard gas was investigated as a therapy for [[Hodgkin's lymphoma]], a form of cancer. Study of the use of similar chemicals as agents for the treatment of cancers led to the discovery of [[mustine]], and the birth of anticancer [[chemotherapy]].
The use of poison gas, including mustard gas, during warfare, a practice known as [[chemical warfare]], was prohibited by the [[Geneva Protocol|Geneva Protocol of 1925]] and the subsequent [[Chemical Weapons Convention|Chemical Weapons Convention of 1993]], which also prohibits the development, production and stockpiling of such weapons.
====Disposal====
Most of the mustard gas found in Germany after World War II was dumped into the [[Baltic Sea]]. Between 1966 and 2002, fishermen have found around 700 chemical weapons outside [[Bornholm]], most of which were mustard gas bombs. When mustard gas is exposed to seawater, it forms a tar-like [[gel]] and maintains its lethality for at least five years. It is possible to mistake a piece of [[polymerization|polymerised]] mustard gas for [[ambergris]], which can lead to severe health problems. [[shell (projectile)|Shell]]s containing mustard gas and other toxic ammunition from World War I (as well as conventional explosives) can still occasionally be found in [[France]] and [[Belgium]]; they used to be disposed of by explosion at sea, but current environmental regulations prohibit this and so the French government is building an automated factory to dispose of the backlog of shells.
In 1972, the [[United States Congress]] banned the practice of disposing chemical weapons into the ocean. However, 64 million pounds of nerve and mustard agents had already been dumped into the ocean waters off the United States by the [[U.S. Army]]. According to a 1998 report created by William Brankowitz, a deputy project manager in the U.S. Army Chemical Materials Agency, the Army created at least 26 chemical weapons dump sites in the ocean off at least 11 states on both the west and east coasts. Additionally because of poor records, they currently only know the rough whereabouts of half of them.
A significant portion of the [[Stockpile (military)|stockpile]] of mustard agent in the United States was stored at the Edgewood Area of [[Aberdeen Proving Ground]] in [[Maryland]]. Approximately 1,621 tons of mustard agent was stored in one-ton (900 kg) containers on the base under heavy guard. A disposal plant built on site neutralized the last of this stockpile in February 2005. This stockpile had priority because of the potential for quick reduction of risk to the community. The closest schools were fitted with overpressurization units to protect the students and staff in the event of a catastrophic explosion and fire at the site. These projects, as well as planning, equipment, and training assistance, were provided to the surrounding community as a part of the Chemical Stockpile Emergency Preparedness Program (CSEPP), a joint US Army and Federal Emergency Management Agency program[http://www.fema.gov/government/grant/csepp1.shtm]. Unexploded shells containing mustard agent and other chemical agents are still present in several test ranges in proximity to Edgewood area schools, but the smaller amounts (4–14 pounds; 2–6 kg) present considerably less risk. They are being systematically detected and excavated for disposal. There are several other sites in the United States where the remaining U.S. stockpiles of chemical agents are awaiting destruction in compliance with international chemical weapons treaties; the largest mustard agent stockpile, approximately 6,196 tons, is stored at the [[Deseret Chemical Depot]] in [[Utah]]. Destruction of this stockpile began in 2006. U.S. mustard agent and other chemical agent storage is managed by the US Army's Chemical Materials Agency[http://www.cma.army.mil/home.aspx]. The Chemical Materials Agency (CMA) manages disposal operations at five of the remaining seven stockpile sites, located in [[Alabama]], [[Arkansas]], [[Indiana]], Utah, and [[Oregon]]; disposal projects at the other two sites, located in [[Kentucky]] and [[Colorado]], are managed by the Program Manager Assembled Chemical Weapons Alternatives (ACWA)[http://www.pmacwa.army.mil/].
==Physiological effects==
[[Image:mustard gas burns.jpg|thumb|right|200px|A soldier with mustard gas burns sustained during [[World War I]]]]
Mustard gas is a strong [[vesicant]] ([[blister]]-causing agent). Due to its alkylating properties, it is also strongly [[mutagen]]ic (causing damage to the [[DNA]] of exposed cells) and [[carcinogen]]ic (cancer causing). Those exposed usually suffer no immediate symptoms. Within 4 to 24 hours the exposure develops into deep, itching or burning blisters wherever the mustard contacted the skin; if the eyes are exposed they become sore and the eyelids swell, possibly leading to [[conjunctivitis]] and blindness. According to the Medical Management of Chemical Casualties handbook, there have been experimental cases in humans where the patient has suffered [[miosis]], or pinpointing of pupils, as a result of the cholinomimetic activity of mustard. At very high concentrations, if inhaled, it causes bleeding and blistering within the [[respiratory system]], damaging the [[mucous membrane]] and causing [[pulmonary edema]]. Blister agent exposure over more than 50% body surface area is usually fatal.
Skin damage can be reduced if [[povidone]] [[iodine]] in a base of [[glycofurol]] is rapidly applied, but since mustard initially has no symptoms, the exposure is usually not identified until the blisters rise. The vesicant property can be neutralised by [[oxidation]] or [[chlorination]]; household bleach ([[sodium hypochlorite]]) or decontamination solution "DS2" (2% NaOH, 70% [[diethylenetriamine]], 28% [[ethylene glycol monomethyl ether]]) can be used.
==See also==
* [[Blister agent]]
* [[Nitrogen mustard]]
* [[Chemical warfare]]
* [[Bioterrorism]]
* [[Chlorine gas]]
==References==
{{reflist}}
==External links==
* [https://ccc.apgea.army.mil/sarea/products/textbook/Web_Version/chapters/chapter_7.htm#mustard Textbook of Military Medicine - Intensive overview of mustard gas] Includes many references to scientific literature
* [http://www.opcw.org/resp/html/mustard.html An overview of the sulfur and nitrogen mustard agents] (Caution: contains graphic images)
* [http://cfrterrorism.org/weapons/mustard.html Questions and Answers for Mustard Gas]
* [http://www.counteract.rutgers.edu UMDNJ-Rutgers University CounterACT Research Center of Excellence] A research center studying sulfur mustard, includes searchable reference library with many early references on sulfur mustard.
* [http://www.ssrichardmontgomery.com/images/Nightmare%20in%20Bari.htm Nightmare in bari]
{{Chemical warfare}}
[[Category:Thioethers]]
[[Category:Organochlorides]]
[[Category:Chemical weapons]]
[[Category:Organosulfur compounds]]
[[Category:IARC Group 1 carcinogens]]
[[af:Yperiet]]
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