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CS gas

2007 Schools Wikipedia Selection. Related subjects: Chemical compounds

                                  CS gas
            Chemical structure of CS Space-filling model of CS
                                  General
               IUPAC                         2-Chlorobenzalmalononitrile
         Other names

                     CS Gas
                     Tear gas
                     ortho-chlorobenzylidene malononitrile
                     Propanedinitrile, [(2-chlorophenyl)methylene]
                     Malononitrile, (o-chlorobenzylidene)
                     β,β-Dicyano-o-chlorostyrene
                     (o-Chlorobenzal)malononitrile
                     (o-Chlorobenzylidene)malononitrile
                     2-Chlorobenzylidenemalononitrile
                     (o-Chlorobenzylidene)malonitrile
                     o-Chlorobenzylidenemalonic nitrile
                     NCI-C55118
                     USAF KF-11
                     2-Chloro BMN
                     b, b-Dicyano-O-chlorostyrene
                     2-Chlorobenzylidenemaloninitrile
                     Propanedinitrile, 2-2-chlorobenzylidene
                     2-(2-Chlorobenzylidene)malononitrile

   Molecular formula                                    C[10]H[5]Cl N[2]
          Molar mass                                        188.6 g/mol
          Appearance                           White crystalline powder,
                                             Colourless gas when burned.
          CAS number                                         [2698-41-1]
                                Properties
       Density/phase                                   1.04 g/cm³, solid
             Soluble                      MiBK, hexane, benzene,
                                          methylene chloride, acetone,
                                           dioxane, ethyl acetate,
                                                           and pyridine.
           Insoluble                                      ethanol, water
       Melting point                       93 °C, (366.15 K), (199.4 °F)
      Boiling point                         310 °C, (583.15 K), (590 °F)
      Vapor pressure           ([[1 10^-3 m|mm]] Hg) 3.4 x 10^-5 at 20°C
          Volatility                                 0.71 mg/m^3 at 25°C
     Toxicity Values                         ICt50 = 10 to 20 mg-min/m^3
                                               LCt50 = 61,000 mg-min/m^3
     Exposure Limits    Workplace Time-Weighted Average:
                                                           0.4 mg/m^3
                                           General Population Limits:
                                                  No standard identified
             Related
           compounds
                SDBS               5-chloro-2-quinolinecarbonitrile
                                   6-chloro-2-quinolinecarbonitrile
                                   7-chloro-2-quinolinecarbonitrile

   CS or 2-chlorobenzalmalononitrile (chemical formula: C[10]H[5]ClN[2])
   is a substance that is used as a riot control agent and is usually
   claimed to be non-lethal by the forces who use it. CS was discovered by
   two Americans, Ben Carson and Roger Staughton in 1928, the first
   letters of the scientists' surnames giving us the name of the
   substance, 'CS' . It was developed and tested secretly at Porton Down
   in Wiltshire, England. Apparently this testing occurred in the 1950s
   and 1960s when CS was used firstly on animals, then subsequently on
   British Army servicemen volunteers. Notably CS has a limited effect on
   animals due to "under-developed tear-ducts and protection by fur". .

Production

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

                ClC[6]H[4]CHO + H[2]C(CN)[2] → ClC[6]H[4]CHC(CN)[2] +
                H[2]O

   CS-chemical-synthesis

   The reaction is catalysed with weak base like piperidine or pyridine.
   The production method has not changed since the substance has been
   discovered by B Carson and R Staughton. Other bases, solvent free
   methods and microwave promotion have been suggested to improve the
   production of the substance.

   The physiological properties have 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. ( sic)"

'CS Gas' - a misnomer

   In common parlance CS is referred to as 'CS gas' or 'Tear gas', however
   this description is incorrect because 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 airborne irritant. For example in
   Waco, Texas, CS was dispersed in droplet form. CS was dissolved in the
   organic solvent dichloromethane (also known as methylene chloride).
   When the volatile dichlormethane evaporated, the CS crystallized into
   fine particles .

   It is worth noting that many types of tear gas 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 tested worldwide. CS has
   become the most popular due to its strong effect and lack of toxicity
   in comparison with other similar chemical agents. The effect of CS on a
   person will depend on whether it is packaged as a solution, or if it is
   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. Certain individuals however have been found to be
   particularly sensitive to CS and or the organic solvents that are
   utilised. Studies on the use of CS on the public have noted that it may
   be ineffective against persons who are either mentally ill or who are
   under the effects of alcohol.

   Persons which had contact with CS sometimes develop allergic contact
   dermatitis, even with blisters and crust. Studies show that most of the
   effects are of a relative short term, but individuals notice some mild
   effects even after months.

Preparations

          Melted and sprayed in the molten form.
          Dissolved in organic solvent.
          CS2 dry powder (CS2 is a siliconized, micro-pulverized form of
          CS).
          CS from thermal grenades by generation of hot gases.

CS incapacitant spray

   CS Incapacitant Spray is used as a temporary incapacitant, to subdue
   attackers, or persons who are violently aggressive, by many police
   forces. The chemical reacts with moisture on the skin and in the eyes
   causing a burning sensation and the immediate forceful shutting of the
   eyes. Reported effects can include tears streaming from the eyes,
   running nose full of mucus, burning in the nose and throat areas,
   disorientation, dizziness and restricted breathing. In highly
   concentrated doses it can also induce severe coughing and vomiting.

   Officers that are trained in the use and application of CS Spray are
   routinely exposed to it as part of their training.

   Although predominantly used by police forces it has also been used in
   criminal attacks in various countries.

   CS is banned from use in war by the 1997 Chemical Weapons Convention
   (signed 1993), as its use could be a trigger for full scale chemical
   warfare. However, domestic police use of it is legal in many countries.

Use geographically

   CS was used to flush the Viet Cong from their tunnels in Vietnam.
   Enlarge
   CS was used to flush the Viet Cong from their tunnels in Vietnam.

Cyprus

   CS was first tested in the field by the British army in Cyprus in 1958.
   At this time it was known by the code name T792.

Vietnam

   It has been reported that thousands of tons of CS gas were used by the
   U.S. forces in Vietnam to bring Viet Cong into the open, other
   estimates report 15 million pounds of CS being used
   A boy in a gas mask during the Battle of the Bogside.
   Enlarge
   A boy in a gas mask during the Battle of the Bogside.

Northern Ireland

   CS gas was heavily used in the Bogside area of Derry, Northern Ireland
   during the " Battle of the Bogside", a two-day riot in August, 1969. A
   total of 1,091 canisters containing 12.5g of CS; and 14 canisters
   containing 50g of CS, were released in the densely populated
   residential area. On 30 August the Himsworth Inquiry was set up to
   investigate the medical effects of its use in Derry. Its conclusions,
   viewed in the political context of the time, still pointed towards the
   necessity of further testing of CS gas before being used as a riot
   control agent. Not long after, the British Army and RUC ceased using CS
   in Northern Ireland. Up to this point, it had been used in crowd
   control scenarios in Derry and Belfast.

Iraq

   Iraq successfully developed CS during the 1970s and during the 1980s
   produced tons of the substance firstly at Salman Pak and later at
   al-Muthanna. Saddam Hussein used CS against the Kurds in his own
   country and against Iran during the Iran-Iraq War.

England, Scotland & Wales

   CS tear gas was first used in mainland Britain to quell rioting in the
   Toxteth area of Liverpool in 1981.

   Personal incapacitant spray (PIS) was sanctioned for use by Police in
   England and Wales in 1995. The CS preparation in this case is CS
   dissolved in the organic solvent MiBK, or methyl iso-butyl ketone, an
   industrial de-greasing agent. The propellant used in this preparation
   is Nitrogen. Officers in Scotland carry CS spray on their belt.

   It has been noted that the solvent MiBK is itself harmful, and can
   cause inflammation, dermatitis, burns to the skin & liver damage.

   A six month trial by 16 police forces in England began on the 1 March
   1996. Only two weeks later, on 16 March 1996, a Gambian asylum seeker,
   Ibrahima Sey was taken to Ilford Police Station in East London. Whilst
   incapacitating the man, police sprayed him with CS and held him on the
   ground for over 15 minutes. The man died, the case was taken to court
   and although a verdict of " Unlawful Killing" was given by the jury at
   the end of the inquiry into his death, no charges were brought against
   any member of the police force.

   The forces that do use the PIS in the UK require that police constables
   should themselves be sprayed with a 3% dissolved CS, during
   self-defence training, in order for them to be able to be authorised to
   carry it as personal protection equipment. They are also trained in
   helping the incapacitated person recover quickly once successfully
   restrained. Most forces currently issue CS Spray to its officers, but
   there has been a recent move for a few forces to issue PAVA Spray (
   pelargonic acid vanillylamide aka nonivamide).

   Notably the CS spray used by UK police has 5 times as much CS as the
   spray used by American police forces (5% dissolved CS and 1% CS
   respectively).

   In 1999 the UK mental health charity MIND called for a suspension in
   its use until it is fully tested and there is proof that CS is safe.

   More recently, in February 2006 there have been calls to have CS spray
   banned in the UK after Dan Ford, from Wareham in Dorset, was
   permanently facially scarred after being sprayed in the face with a
   police CS canister. Mr Ford was subsequently advised by doctors to stay
   out of sunlight for at least 12 months. About the incident, his cousin,
   Donna Lewis, was quoted as saying:

     "To look at him, it was like looking at a melting man, with liquid
     oozing from his face."

   However it is not yet confirmded that Mr Ford's injury is a reaction to
   been exposed to police CS spray, or whether an unrelated chemical
   exposure has caused the injury. An investigation is ongoing.

   The British Armed Forces use CS gas annually to test their NBC
   equipment. During initial training they introduce recruits to CS gas by
   ordering them into a small enclosed space known as a Respirator Test
   Facility (RTF) and igniting chemical tablets to induce CS production.
   When recruits have carried out their NBC drills (which include
   immediate actions for decontamination, an eating drill, a drinking
   drill and a gas mask canister change) the NCO IC RTF will order them to
   remove their respirators and inhale the aerosol CS. This is apparently
   to inform the trainees what CS effects feel like so they can have trust
   in their equipment and procedures thus proving to themselves that it
   works in the contaminated environment in training and then are able to
   take this confidence to the battlefield environment.

USA

   CS is used by many police forces within the USA, for example the NYPD,
   and it was most infamously used as one of a number of techniques by FBI
   law enforcement officials in the 1993 Waco Siege.

   Members of the US armed forces are often exposed to CS during initial
   training to show the importance of proper wearing of a gas mask as well
   as to develop confidence in the equipment's effectiveness (many
   soldiers misattribute the feeling of air rushing into the mask as being
   caused by a poor seal). As the agent's presence quickly reveals
   improper fit or seal of the mask's rubber gaskets against the face, it
   is sometimes used during training refresher courses or equipment
   maintenance exercises as well.

Elsewhere

   Police fire tear gas at protesters in Quebec.
   Enlarge
   Police fire tear gas at protesters in Quebec.

   CS was used in large quantities to quell a peaceful protest in Lusaka,
   Zambia in July 1997, Amnesty International reported that it had been
   manufactured by the UK company Pains-Wessex. Subsequently, Amnesty
   called for an export ban when the receiving regime is either not fully
   trained in the use of CS, or had shown usage "contrary to the
   manufacturer’s instructions".

   In September 2000, the Guardian Newspaper revealed how a UK company,
   HPP, used legal loopholes to export CS to a private security company in
   Rwanda, in breach of United Nations sanctions. The Guardian also
   reported that CS was used by the Hutu militia in Rwanda to flush Tutsis
   out of buildings before hacking them to death.

   CS has been used by the government in South Africa; by Israel against
   Palestinians and Israelis; by the South Korean government in Seoul, and
   during the Balkan conflicts.

   CS tear gas was used at the G8 protests in Genoa, Italy and Quebec,
   Canada during the FTAA anti-globalization demonstrations during the
   Quebec City Summit of the Americas.

   The Canadian and Australian Armies train their soldiers with CS gas in
   a manner similar to that of the USA, as it is a basic part of NBC
   (nuclear, biological, chemical) or more recently within NATO, CBRN
   (Chemical, Biological, Radiological, Nuclear) training. Gas is released
   by burning tablets, usually in a tent or a small building reserved for
   this purpose (a "gas hut"), and soldiers are exposed to it on three
   occasions. During the first two exposures the soldier enters the tent
   or gas hut wearing a gas mask. During the first exposure he removes his
   gas mask and leaves the tent or hut. During the second exposure he must
   remove the mask, receive facial exposure, then replace and clear the
   mask. In the third exposure he enters the tent unprotected, must fit
   and clear the gas mask before leaving. Other drills such as drinking
   and under-mask decontamination are usually also practised yearly.
   Symptoms are a burning sensation on any moist skin, whether due to
   perspiration or other fluids such as tears or in the nasal membranes.

Toxicity

   Although described as a non-lethal weapon for crowd control, many
   studies have raised doubts about this classification. As well as
   creating severe pulmonary damage, CS can also significantly damage the
   heart and liver.

   On 28 September 2000, Prof. Dr. Uwe Heinrich released a study
   commissioned by John C. Danforth, of 'The Office of Special Counsel',
   to investigate the use of CS by the FBI at the Branch Davidians' Mount
   Carmel compound. In summary, he 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."

   Many reports have associated CS exposure with miscarriages , this is
   consistent with its reported clastogenic effect (abnormal chromosome
   change) on mammalian cells.

   When CS is metabolized, cyanide can be detected in human tissue.
   According to the United States Army Centre for Health Promotion and
   Preventive Medicine, CS emits "very toxic fumes" when heated to
   decomposition, and at specified concentrations CS gas is an immediate
   danger to life and health. They also state that those exposed to CS gas
   should seek medical attention immediately .

Decontamination

   Decontamination can be performed by washing with an alkaline solution
   of water and 5% sodium bisulfite.

   Retrieved from " http://en.wikipedia.org/wiki/CS_gas"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
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