The chemical substance CS (other names are chlorobenzalmalonodinitrile, O-chlorobenzylidene malononitrile) is one of the types of irritants - compounds of tear action. It was used (and in some countries is still used) for military purposes, to combat riots, disperse demonstrators, as well as in self-defense means - in gas cartridges, cartridges for gas pistols. The intense burning sensation it causes in the eyes creates such irritation that the person loses orientation in space and the ability to resist.
History of Creation
CS was first discovered in 1928 at Middlebury College in Vermont, England. It was synthesized by two American chemists B. Corson and R. Stone. They were systematically studying the reactions of aldehydes and ketones with malonic acid dinitrile. As a result, several new compounds were obtained, among which was chlorobenzalmalonodinitrile. The name of the substance CS comes from the first letters of the names of its discoverers (Corson and Stoughton). Even then, his psychophysiologicalproperties. In their 13-page report, scientists recorded that it causes severe tearing and sneezing.
At that time, this connection did not attract much attention. However, in the late 50s. 20th century they became interested in specialists from the British Ministry of Defense, who at that time were actively engaged in the search for effective chemical weapons. Soon it was tested in practice, first on animals, then on the volunteers of the English army, and after that - during the fighting in some countries. It was commercially synthesized at the Nanskjuk chemical plant, and in 1954 CS was adopted by the police and the US National Guard.
Chemical properties
Chlorobenzalmalonodinitrile is a chemically stable compound. It has the following features:
- most reactions involve an ethylene bond, which is capable of adding nucleophiles to break the C=C bond;
- poor solubility in water and water-alcohol solutions;
- hydrolysis is accelerated in the presence of alkalis and slowed down by acids;
- when heated, the solubility becomes higher and reaches 99% at 40°C for 4 hours;
- reactions with oxidizing agents cause loss of irritating properties;
- during solveolysis with water, decomposition into O-chlorobenzaldehyde and malononitrile is observed.
The structural formula of the substance CS is shown in the figure below. ATchemical industry, it is obtained as a result of the Knoevenagel reaction (when aldehydes and ketones are condensed in the presence of bases), a process that is the reverse of hydrolysis.
Physical properties
Chlorobenzalmalonodinitrile has the following physical properties:
- density - 1040 kg/m3;
- relative vapor density in air - 6, 5;
- thermal stability up to 300°C;
- boiling point - 315°С;
- melting point - 95°C;
Externally, the compound looks like a solid, colorless substance with a peppery smell. Its decontamination is carried out by boiling in water-alcohol alkaline solutions.
Effect on the human body
Chlorobenzalmalonodinitrile aerosol can cause the following adverse effects:
- strong lacrimation;
- burning sensation in the nasopharynx;
- chest pain;
- conjunctivitis;
- dryness, skin irritation;
- nosebleed.
Although not lethal, CS can cause damage to the lungs, liver, and heart at concentrations of 0.27 mg/L and above, especially in confined spaces and with prolonged exposure. Animal experiments have also shown that it has a teratogenic effect. A dangerous concentration in the air is 0.002 mg/l. The toxic effect is detected within a few seconds, and disappears in 15-30 minutes. Skin redness may persist forseveral hours.
Application
In 1962, the US began supplying the irritating substance CS to South Vietnam. After 2 years, this compound was used in the fight against the partisan movement during the civil war. From that moment on, it began to be widely used by American troops. According to some reports, the total amount of chlorobenzalmalononitrile consumed during the years of the Vietnam War is more than 6,000 tons.
After successful use for military purposes, it began to be used by the police when establishing public order. However, when its teratogenic properties were discovered, it was withdrawn from service in European countries. According to the 1993 Chemical Weapons Convention, this compound is prohibited from military use, but in a number of countries (Bahrain, Nepal, South Korea, Egypt) it is still in use.
There are safer irritants that are similar in action to CS. Aerosol morpholide of pelargonic acid also irritates the organs of vision and breathing, but these symptoms disappear faster (in 10-15 minutes in fresh air) and do not require treatment. This chemical is much less toxic.
Shapes
There are several ways to obtain an aerosol of chlorobenzalmalononitrile:
- dissolving in organic solvents;
- melting and spraying in liquid form;
- use of siliconized powder (to prevent clumping of the activesubstances);
- introduction of explosive munitions (artillery shells, chemical bombs, aviation cassettes, hand grenades), pyrotechnic mixtures;
- application in mechanical aerosol generators and dispersants.
Environmental impact
The use of CS as a toxic agent may result in its release into the atmosphere, where it can be both in a vapor state and in the form of a suspension. The decomposition of the compound in air occurs as a result of a photochemical reaction with hydroxyl radicals. The half-life is about 110 hours.
In the soil, this compound has low mobility. In water and land, the main process leading to the breakdown of CS is hydrolysis rather than evaporation. This substance has a weaker effect on animals than on humans.
Antidote
There is no specific antidote. The following measures are recommended for chlorobenzalmalononitrile damage:
- get out into the fresh air (in the presence of wind, you must be on the windward side);
- open eyes wide;
- take off clothes;
- rinse eyes with clean, cool water, 1% aqueous sodium bicarbonate solution, or saline (you can make your own by adding 1 tsp table s alt to 1 liter of water);
- take a shower (starting with washing your hair).
When in contact with the compound, as well as with the injured person, it is necessary to use personal protective equipment -goggles, gas mask, rubber gloves. Before washing contaminated clothing, it is recommended to air it outdoors for a day.
