CS gas

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The compound 2-chlorobenzalmalononitrile (also called o-chlorobenzylidene malononitrile; chemical formula: C10H5ClN2), a cyanocarbon, is the defining component of the lachrymatory agent commonly referred to as CS gas, which is used as a riot control agent.

Contents

CS gas
CS gas.svg
CS-gas-3D-vdW.png
Names
Preferred IUPAC name
[(2-Chlorophenyl)methylidene]propanedinitrile
Other names
2-(2-Chlorobenzylidene)malononitrile
2-Chlorobenzalmalononitrile
o-Chlorobenzylidene malononitrile
Tear gas
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.018.435 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 220-278-9
PubChem CID
RTECS number
  • OO3675000
UNII
UN number 2810, 3276, 2811
  • InChI=1S/C10H5ClN2/c11-10-4-2-1-3-9(10)5-8(6-12)7-13/h1-5H Yes check.svgY
    Key: JJNZXLAFIPKXIG-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C10H5ClN2/c11-10-4-2-1-3-9(10)5-8(6-12)7-13/h1-5H
    Key: JJNZXLAFIPKXIG-UHFFFAOYAA
  • Clc1ccccc1\C=C(/C#N)C#N
Properties
C10H5ClN2 [1]
Molar mass 188.6 g/mol [2]
AppearanceWhite crystalline powder
Colourless gas when burned
Odor Pepper-like [3]
Density 1.04 g/cm3
Melting point 93 °C (199 °F; 366 K)
Boiling point 310 °C (590 °F; 583 K) [4]
Insoluble
Vapor pressure 3.4×10−5  mmHg at 20 °C
Hazards
GHS labelling:
GHS-pictogram-acid.svg GHS-pictogram-skull.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H302, H314, H330, H335, H372, H410
P260, P261, P264, P270, P271, P273, P280, P284, P301+P312, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P314, P320, P321, P330, P363, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
1
0
Lethal dose or concentration (LD, LC):
  • 1806 mg/m3 (rat, 45 min)
  • 2753 mg/m3 (mouse, 20 min)
  • 1802 mg/m3 (rabbit, 10 min)
  • 2326 mg/m3 (guinea pig, 10 min) [5]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 0.05 ppm (0.4 mg/m3) [3]
REL (Recommended)
C 0.05 ppm (0.4 mg/m3) [skin] [3]
IDLH (Immediate danger)
2 mg/m3 [3]
Related compounds
Related compounds
 SDBS

5-chloro-2-quinolinecarbonitrile
6-chloro-2-quinolinecarbonitrile
7-chloro-2-quinolinecarbonitrile

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Exposure causes a burning sensation and tearing of the eyes to the extent that the subject cannot keep their eyes open, and a burning irritation of the mucous membranes of the nose, mouth and throat, resulting in profuse coughing, nasal mucus discharge, disorientation, and difficulty breathing, partially incapacitating the subject. CS gas is an aerosol of a volatile solvent (a substance that dissolves other active substances and that easily evaporates) and 2-chlorobenzalmalononitrile, which is a solid compound at room temperature. CS gas is generally accepted as being non-lethal.

History

CS gas was first synthesized by two Americans, Ben Corson and Roger Stoughton, [6] at Middlebury College in 1928, and the chemical's name is derived from the first letters of the scientists' surnames. [7] [8]

CS was developed and tested secretly at Porton Down in Wiltshire, UK, in the 1950s and '60s. CS was used first on animals, and subsequently on British Army servicemen volunteers. CS has less effect on animals because they have different tear ducts and, in the case of non-human mammals, their fur inhibits the free entry of the gas. [9]

As recently as 2002, the U.S. State Department Bureau of International Security and Nonproliferation of Colin Powell made a firm distinction between "riot-control agents" such as CS gas, and "lethal chemical weapons." The Bureau cited support for this position from the U.K. and Japan. [10]

Production

CS is synthesized by the reaction of 2-chlorobenzaldehyde and malononitrile via the Knoevenagel condensation:

Preparation of CS CS-Gas-Synthese.svg
Preparation of CS
ClC6H4CHO + H2C(CN)2 → ClC6H4CHC(CN)2 + H2O

The reaction is catalysed with a weak base like piperidine or pyridine. The production method has not changed since the substance was discovered by Corson and Stoughton. [11] Other bases, solvent free methods and microwave promotion have been suggested to improve the production of the substance. [12]

The physiological properties had been discovered already by the chemists first synthesising the compound in 1928: "Physiological Properties. Certain of these dinitriles have the effect of sneeze and tear gases. They are harmless when wet but to handle the dry powder is disastrous." [11]

Use as an aerosol

As 2-chlorobenzalmalononitrile is a solid at room temperature, not a gas, a variety of techniques have been used to make this solid usable as an aerosol:

In the Waco Siege in the United States, CS was dissolved in the organic solvent dichloromethane (also known as methylene chloride). The solution was dispersed as an aerosol via explosive force and when the highly volatile dichloromethane evaporated, CS crystals precipitated and formed a fine dispersion in the air. [2]

Effects

CS Gas used on 1 May 2013 in Istanbul CS gas 1330189.JPG
CS Gas used on 1 May 2013 in Istanbul
Tear gas shells used in Istanbul in 2013 Tear gas shells used in istanbul in 2013.jpg
Tear gas shells used in Istanbul in 2013
CS gas shells used in Taksim Gezi Park, Istanbul, May 2013 CS gas shells, Taksim Gezi Park, Istanbul, 31-05-2013.jpg
CS gas shells used in Taksim Gezi Park, Istanbul, May 2013

Many types of tear gas and other riot control agents have been produced with effects ranging from mild tearing of the eyes to immediate vomiting and prostration. CN and CS are the most widely used and known, but around 15 different types of tear gas have been developed worldwide, e.g. adamsite or bromoacetone, CNB, and CNC. CS has become the most popular due to its strong effect. The effect of CS on a person will depend on whether it is packaged as a solution or used as an aerosol. The size of solution droplets and the size of the CS particulates after evaporation are factors determining its effect on the human body. [13]

The chemical reacts with moisture on the skin and in the eyes, causing a burning sensation and the immediate forceful and uncontrollable shutting of the eyes. Effects usually include tears streaming from the eyes, profuse coughing, exceptional nasal discharge that is full of mucus, burning in the eyes, eyelids, nose and throat areas, disorientation, dizziness and restricted breathing. It will also burn the skin where sweaty or sunburned. In highly concentrated doses, it can also induce severe coughing and vomiting. Most of the immediate effects wear off within a few hours (such as exceptional nasal discharge and profuse coughing), although respiratory, gastrointestinal, and oral symptoms may persist for months. [14] [15] Excessive exposure can cause chemical burns resulting in permanent scarring. [16]

Adults exposed to tear gas during the 2020 protests in Portland Oregon (USA) also reported menstrual changes (899; 54.5% of 1650 female respondents). Exposure to tear gas is associated with avoidable healthcare utilization. [17]

Secondary effects

People or objects contaminated with CS gas can cause secondary exposure to others, including healthcare professionals and police. In addition, repeated exposure may cause sensitisation. [18]

Toxicity

TRPA1 (Transient Receptor Potential-Ankyrin 1) ion channel expressed on nociceptors (especially trigeminal) has been implicated as the site of action for CS gas in rodent models. [19] [20]

Although described as a non-lethal weapon for crowd control, studies have raised doubts about this classification. CS can cause severe pulmonary damage and can also significantly damage the heart and liver. [21]

On 28 September 2000, Prof. Dr. Uwe Heinrich released a study commissioned by John C. Danforth, of the United States Office of Special Counsel, to investigate the use of CS by the FBI at the Branch Davidians' Mount Carmel compound. He said no human deaths had been reported, but concluded that the lethality of CS used would have been determined mainly by two factors: whether gas masks were used and whether the occupants were trapped in a room. He suggests that if no gas masks were used and the occupants were trapped, then, "there is a distinct possibility that this kind of CS exposure can significantly contribute to or even cause lethal effects". [2]

CS gas can have a clastogenic effect (abnormal chromosome change) on mammalian cells, but no studies have linked it to miscarriages or stillbirths. [21] In Egypt, CS gas was reported to be the cause of death of several protesters in Mohamed Mahmoud Street near Tahrir square during the November 2011 protests. The solvent in which CS is dissolved, methyl isobutyl ketone (MIBK), is classified as harmful by inhalation; irritating to the eyes and respiratory system; and repeated exposure may cause skin dryness or cracking. [22]

See also

Related Research Articles

<span class="mw-page-title-main">Inhalant</span> Chemical, often household, breathed in to cause intoxication

Inhalants are a broad range of household and industrial chemicals whose volatile vapors or pressurized gases can be concentrated and breathed in via the nose or mouth to produce intoxication, in a manner not intended by the manufacturer. They are inhaled at room temperature through volatilization or from a pressurized container, and do not include drugs that are sniffed after burning or heating. For example, amyl nitrite (poppers), gasoline, nitrous oxide and toluene – a solvent widely used in contact cement, permanent markers, and certain types of glue – are considered inhalants, but smoking tobacco, cannabis, and crack cocaine are not, even though these drugs are inhaled as smoke or vapor.

Acetonitrile, often abbreviated MeCN, is the chemical compound with the formula CH3CN and structure H3C−C≡N. This colourless liquid is the simplest organic nitrile. It is produced mainly as a byproduct of acrylonitrile manufacture. It is used as a polar aprotic solvent in organic synthesis and in the purification of butadiene. The N≡C−C skeleton is linear with a short C≡N distance of 1.16 Å.

<span class="mw-page-title-main">Methyl isocyanate</span> Chemical compound

Methyl isocyanate (MIC) is an organic compound with the molecular formula CH3NCO. Synonyms are isocyanatomethane and methyl carbylamine. Methyl isocyanate is an intermediate chemical in the production of carbamate pesticides (such as carbaryl, carbofuran, methomyl, and aldicarb). It has also been used in the production of rubbers and adhesives. As an extremely toxic and irritating compound, it is very hazardous to human health. MIC was the principal toxicant involved in the Bhopal gas disaster, which eventually killed around 20,000 people in total as per official figures. It is also a very potent lachrymatory agent.

<span class="mw-page-title-main">Pepper spray</span> Inflammatory agent

Pepper spray, oleoresin capsicum spray, OC spray, capsaicin spray, or capsicum spray is a lachrymator product containing the compound capsaicin as the active ingredient that irritates the eyes to cause burning and pain sensations, as well as temporary blindness. Its inflammatory effects cause the eyes to close, temporarily taking away vision. This temporary blindness allows officers to more easily restrain subjects and permits people in danger to use pepper spray in self-defense for an opportunity to escape. It also causes temporary discomfort and burning of the lungs which causes shortness of breath. Pepper spray is used as a less lethal weapon in policing, riot control, crowd control, and self-defense, including defense against dogs and bears.

<span class="mw-page-title-main">Nitrogen dioxide</span> Chemical compound with formula NO₂

Nitrogen dioxide is a chemical compound with the formula NO2. One of several nitrogen oxides, nitrogen dioxide is a reddish-brown gas. It is a paramagnetic, bent molecule with C2v point group symmetry. Industrially, NO2 is an intermediate in the synthesis of nitric acid, millions of tons of which are produced each year, primarily for the production of fertilizers.

<span class="mw-page-title-main">Phenacyl chloride</span> Chemical compound

Phenacyl chloride, also commonly known as chloroacetophenone, is a substituted acetophenone. It is a useful building block in organic chemistry. Apart from that, it has been historically used as a riot control agent, where it is designated CN. It should not be confused with cyanide, another agent used in chemical warfare, which has the chemical structure CN−. Chloroacetophenone is thermally stable, and is the only tear agent that is distillable at ambient conditions.

<span class="mw-page-title-main">Dichloromethane</span> Chemical compound

Dichloromethane is an organochlorine compound with the formula CH2Cl2. This colorless, volatile liquid with a chloroform-like, sweet odor is widely used as a solvent. Although it is not miscible with water, it is slightly polar, and miscible with many organic solvents.

<span class="mw-page-title-main">Chloroethane</span> Chemical compound commonly known as ethyl chloride

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<span class="mw-page-title-main">Riot control</span> Measures taken against unlawful or violent crowds of people

Riot control measures are used by law enforcement, military, paramilitary or security forces to control, disperse, and arrest people who are involved in a riot, unlawful demonstration or unlawful protest.

<span class="mw-page-title-main">CR gas</span> Chemical compound

CR gas or dibenzoxazepine (chemical name dibenz[b,f][1,4]oxazepine, is an incapacitating agent and a lachrymatory agent. CR was developed by the British Ministry of Defence as a riot control agent in the late 1950s and early 1960s. A report from the Porton Down laboratories described exposure as "like being thrown blindfolded into a bed of stinging nettles", and it earned the nickname "firegas".

Volatile organic compounds (VOCs) are organic compounds that have a high vapor pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the surrounding air, a trait known as volatility.

<span class="mw-page-title-main">Air freshener</span> Product used to mask odors

Air fresheners are products designed to reduce unwanted odors in indoor spaces, or to introduce pleasant fragrances, or both. They typically emit fragrance to mask odors, but may use other methods of action such as absorbing, bonding to, or chemically altering compounds in the air that produce smells, killing organisms that produce smells, or disrupting the sense of smell to reduce perception of unpleasant smells.

Cyanogen chloride is a highly toxic chemical compound with the formula CNCl. This linear, triatomic pseudohalogen is an easily condensed colorless gas. More commonly encountered in the laboratory is the related compound cyanogen bromide, a room-temperature solid that is widely used in biochemical analysis and preparation.

<span class="mw-page-title-main">Tear gas</span> Non-lethal chemical weapon

Tear gas, also known as a lachrymatory agent or lachrymator, sometimes colloquially known as "mace" after the early commercial self-defense spray, is a chemical weapon that stimulates the nerves of the lacrimal gland in the eye to produce tears. In addition, it can cause severe eye and respiratory pain, skin irritation, bleeding, and blindness. Common lachrymators both currently and formerly used as tear gas include pepper spray, PAVA spray (nonivamide), CS gas, CR gas, CN gas, bromoacetone, xylyl bromide and Mace.

<span class="mw-page-title-main">Methyl isobutyl ketone</span> Chemical compound

Methyl isobutyl ketone (MIBK, 4-methylpentan-2-one) is an organic compound with the condensed chemical formula (CH3)2CHCH2C(O)CH3. This ketone is a colourless liquid that is used as a solvent for gums, resins, paints, varnishes, lacquers, and nitrocellulose.

<span class="mw-page-title-main">Adamsite</span> Chemical compound

Adamsite or DM is an organic compound; technically, an arsenical diphenylaminechlorarsine, that can be used as a riot control agent. DM belongs to the group of chemical warfare agents known as vomiting agents or sneeze gases. First synthesized in Germany by Heinrich Otto Wieland in 1915, it was independently developed by the US chemist Roger Adams at the University of Illinois in 1918.

<span class="mw-page-title-main">Malononitrile</span> Organic compound with formula CH2(CN)2

Malononitrile is an organic compound nitrile with the formula CH2(CN)2. It is a colorless or white solid, although aged samples appear yellow or even brown. It is a widely used building block in organic synthesis.

<span class="mw-page-title-main">Tetramethylsuccinonitrile</span> Chemical compound

Tetramethylsuccinonitrile or TMSN is an organic compound with the formula (C(CH3)2CN)2, classified as a dinitrile. It is a colorless and odorless solid. TMSN is the byproduct from the use of some radical initiators used in polymer manufacture.

<span class="mw-page-title-main">Butane-1-thiol</span> Chemical compound

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References

  1. ↑ Williams KE. "Detailed Facts About Tear Agent O-Chlorobenzylidene Malononitrile (CS)]" (PDF). U.S. Army Center for Health Promotion and Preventive Medicine. Archived from the original (PDF) on 26 September 2007.
  2. 1 2 3 4 Heinrich U (September 2000). "Possible lethal effects of CS tear gas on Branch Davidians during the FBI raid on the Mount Carmel compound near Waco, Texas" (PDF). Archived (PDF) from the original on 25 December 2014. Retrieved 23 September 2007.
  3. 1 2 3 4 NIOSH Pocket Guide to Chemical Hazards. "#0122". National Institute for Occupational Safety and Health (NIOSH).
  4. ↑ Hoenig, Steven L. (2006). Compendium of Chemical Warfare Agents. Springer. p. 138. ISBN   978-0-387-34626-7.
  5. ↑ "o-Chlorobenzylidene malononitrile". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  6. ↑ Corson BB, Stoughton RW (1928). "Reactions of Alpha, Beta-Unsaturated Dinitriles". Journal of the American Chemical Society. 50 (10): 2825–2837. doi:10.1021/ja01397a037.
  7. ↑ "CS" . Oxford English Dictionary (Online ed.). Oxford University Press.(Subscription or participating institution membership required.)
  8. ↑ "CS, chemical compound Archived 19 December 2005 at the Wayback Machine ". columbia.thefreedictionary.com Archived 29 July 2005 at the Wayback Machine . Retrieved on 23 September 2007.
  9. ↑ "Orthochlorobenzylidenemalononitrile ClC6H4CHCCN(CN)2 Archived 28 November 2006 at the Wayback Machine ". Zarc International. Retrieved on 23 September 2007
  10. ↑ "Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases and of Bacteriological Methods of Warfare (Geneva Protocol)". U.S. Department of State. 25 September 2002. Retrieved 24 August 2013.
  11. 1 2 Corson BB, Stoughton RW (1928). "Reactions of Alpha, Betha-Unsaturated Dinitriles". J Am Chem Soc. 50 (10): 2825–2837. doi:10.1021/ja01397a037.
  12. ↑ Pande A, Ganesan K, Jain AK, Gupta PK, Malhotr RC (2005). "Novel Eco-Friendly Process for the Synthesis of 2-Chlorobenzylidenemalononitrile and ITS Analogues Using Water As a Solvent". Org Proc Res Develop. 9 (2): 133–136. doi:10.1021/op0498262.
  13. ↑ "Safer Restraint: A report of the conference held in April 2002 at Church House, Westminster." Police Complaints Authority. Retrieved on 23 September 2007
  14. ↑ Karagama YG, Newton JR, Newbegin CJ (April 2003). "Short-term and long-term physical effects of exposure to CS spray". Journal of the Royal Society of Medicine. 96 (4): 172–4. doi:10.1177/014107680309600404. PMC   539444 . PMID   12668703.
  15. ↑ Torgrimson-Ojerio BN, Mularski KS, Peyton MR, Keast EM, Hassan A, Ivlev I (April 2021). "Health issues and healthcare utilization among adults who reported exposure to tear gas during 2020 Portland (OR) protests: a cross-sectional survey". BMC Public Health. 21 (1): 803. doi: 10.1186/s12889-021-10859-w . PMC   8074355 . PMID   33902512.
  16. ↑ "CS spray man 'scarred for life'" Archived 5 March 2016 at the Wayback Machine . BBC News. 2 February 2006. Retrieved on 23 September 2007
  17. ↑ Torgrimson-Ojerio BN, Mularski KS, Peyton MR, Keast EM, Hassan A, Ivlev I (April 2021). "Health issues and healthcare utilization among adults who reported exposure to tear gas during 2020 Portland (OR) protests: a cross-sectional survey". BMC Public Health. 21 (1): 803. doi: 10.1186/s12889-021-10859-w . PMC   8074355 . PMID   33902512.
  18. ↑ Carron PN, Yersin B (June 2009). "Management of the effects of exposure to tear gas". BMJ. 338: b2283. doi:10.1136/bmj.b2283. PMID   19542106. S2CID   7870564.
  19. ↑ Bessac BF, Sivula M, von Hehn CA, Caceres AI, Escalera J, Jordt SE (April 2009). "Transient receptor potential ankyrin 1 antagonists block the noxious effects of toxic industrial isocyanates and tear gases". FASEB Journal. 23 (4): 1102–14. doi: 10.1096/fj.08-117812 . PMC   2660642 . PMID   19036859.
  20. ↑ Brône B, Peeters PJ, Marrannes R, Mercken M, Nuydens R, Meert T, Gijsen HJ (September 2008). "Tear gasses CN, CR, and CS are potent activators of the human TRPA1 receptor". Toxicology and Applied Pharmacology. 231 (2): 150–6. doi:10.1016/j.taap.2008.04.005. PMID   18501939.
  21. 1 2 Hu H, Fine J, Epstein P, Kelsey K, Reynolds P, Walker B (August 1989). "Tear gas--harassing agent or toxic chemical weapon?". JAMA. 262 (5): 660–3. doi:10.1001/jama.1989.03430050076030. PMID   2501523.
  22. ↑ "MSDS for 99% 4-Methyl-2-pentanone (MIBK)" (PDF). Alfa Aesar. Archived from the original (PDF) on 16 August 2018. Retrieved 7 January 2013.

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