Chemical substance CS (other names - chlorobenzalmalonodinitrile, O-chlorobenzylidene malononitrile) is one of the types of irritants - tear compounds. It was used (and is still used in some countries) for military purposes, to combat public unrest, disperse protesters, and also in self-defense means - in gas cartridges, cartridges for gas pistols. The burning sensation caused by him in the eyes creates such irritation that a person loses orientation in space and the ability to resist.
History of creation
Substance CS was first obtained in 1928 at Middlebury College in Vermont (England). It was synthesized by two American chemical scientists B. Corson and R. Stone. They were engaged in a systematic study of the reactions of aldehydes and ketones with malonic acid dinitrile. As a result, several new compounds were obtained, among which was chlorobenzalmalonodinitrile. The name CS comes from the first letters of the names of its discoverers (Corson and Stoughton). Even then, his psychophysiological properties were noticed. In their report on 13 pages, scientists recorded that it causes severe lacrimation and sneezing.
At that time, this compound did not attract much attention. However, in the late 50s. XX century He was interested in specialists from the UK Department of Defense, who at that time were actively seeking effective chemical weapons. Soon it was tested in practice, first on animals, then on volunteers of the English army, and after that - during the conduct of hostilities in some countries. At a chemical plant in Nanskyuk, its industrial synthesis was established, and in 1954 the poisonous substance CS was adopted by the police and the US National Guard.
Chemical properties
Chlorobenzalmalonodinitrile is a chemically stable compound. The following features are characteristic of it:
most reactions involve an ethylene bond, which is capable of attaching nucleophiles with a C = C bond cleavage;
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 a temperature of 40 ° C for 4 hours;
- in reactions with oxidizing agents, a loss of irritating properties occurs;
- during solvolysis with water, decomposition into O-chlorobenzaldehyde and malonodinitrile is observed.
The structural formula of CS is shown in the figure below. In the chemical industry, it is obtained as a result of the Knevenagel reaction (during the condensation of aldehydes and ketones in the presence of bases), a process opposite to hydrolysis.
Physical properties
Chlorobenzalmalonodinitrile has the following physical properties:
- density - 1040 kg / m 3 ;
- relative vapor density in the air - 6.5;
- thermal stability - up to 300 ° ;
- boiling point - 315 ° C;
- melting point - 95 ° C;
Externally, the compound looks like a solid, colorless substance with a pepper smell. Its deactivation is carried out by boiling in water-alcohol alkaline solutions.
Effects on the human body
Chlorobenzalmalonodinitrile in the form of an aerosol can cause the following negative effects:
- severe lacrimation;
- burning sensation in the nasopharynx;
- pain behind the sternum;
- conjunctivitis;
- dryness, skin irritation;
- nose bleed.
Although CS is not deadly, it can cause damage to the lungs, liver and heart at concentrations of 0.27 mg / L or higher, especially in confined spaces and with prolonged exposure. Animal experiments have also shown that it has a teratogenic effect. A hazardous concentration in the air is 0.002 mg / L. The toxic effect is detected within a few seconds, and passes in 15-30 minutes. Redness of the skin may persist for several hours.
Application
In 1962, the supply of the irritating substance CS to South Vietnam began from the USA. 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 chlorobenzalmalonodinitrile consumed during the years of the Vietnam War is more than 6,000 tons.
After successful use for military purposes, they began to use it in the police when restoring 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 for military use, but it is still in use in a number of countries (Bahrain, Nepal, South Korea, Egypt).
There are safer irritants similar in substance to CS. Pelargonic acid morpholide in the form of an aerosol also irritates the organs of vision and respiration, but these symptoms pass faster (in 10-15 minutes in the fresh air) and do not require treatment. This chemical is much less toxic.
Forms
To obtain an aerosol of chlorobenzalmalonodinitrile, several methods are used:
- dissolution in organic solvents;
- melting and spraying in liquid form;
- the use of siliconized powder (to prevent clumping of the active substance);
- the introduction of explosive ordnance (artillery shells, chemical bombs, air cartridges, hand grenades), pyrotechnic mixtures;
- application in mechanical aerosol generators and dispersants.
Environmental impact
The use of CS as a toxic agent can lead to its release into the atmosphere, where it can be both in a vaporous state and in suspension. The decomposition of a compound in air occurs as a result of a photochemical reaction with hydroxyl radicals. The half-life is about 110 hours.
In soil, this compound has low mobility. In water and land, hydrolysis rather than evaporation is the main process leading to the decomposition of CS. This substance has a weaker effect on animals than on humans.
Antidote
There is no specific antidote. If chlorobenzalmalonodinitrile is affected, the following measures are recommended:
- go out into the fresh air (if there is wind, you must be on the windward side);
- open your eyes wide;
- take off the clothes;
- rinse your eyes with clean cool water, 1% aqueous sodium bicarbonate solution or saline (it can be prepared by yourself, adding 1 tsp of table salt to 1 liter of water);
- take a shower (starting with washing your hair).
In contact with the compound, as well as with the injured person, it is necessary to use personal protective equipment - glasses, gas mask, rubber gloves. Before washing contaminated clothing, it is recommended to ventilate it in the open air during the day.