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Chloroform, a colorless liquid with a sweet scent, was historically used as an anesthetic but is now mainly used in industrial processes. It is produced industrially by combining methane with chlorine and is found in small quantities in water and the atmosphere. Chloroform is toxic and can release vapor quickly when exposed to air, so it must be handled with care. Its major use is in the production of polytetrafluoroethylene (PTFE), a heat-resistant plastic. Chloroform is considered moderately toxic and can have adverse effects on the liver and kidneys. It may also pose a cancer risk.
Chloroform, also known as trichloromethane, is a colorless and sweetly scented liquid with the chemical formula CHCl3. It is best known for its historical use as a general anesthetic, though it has since been abandoned due to safety concerns. Today, trichloromethane is used in a variety of industrial processes, including the production of plastics, refrigerants and solvents. It is found in small quantities in water and in the atmosphere; most of this comes from natural sources. Chloroform is toxic and releases vapor quickly when exposed to air, so it must be handled with care.
Production
This compound was originally produced by the reaction of ethanol or acetone with bleach powder – calcium hypochlorite. In modern times, however, it is produced industrially by combining methane with chlorine. Small amounts of the chemical are produced naturally by marine life, such as algae, and by the decomposition of plant remains in the soil. The main human sources in the environment come from the use of chlorine as a bleaching agent in paper mills and from the chlorination of drinking water. Chlorine reacts with various organic compounds to produce trichloromethane, but the amounts present in chlorinated water are minute and are not thought to pose any risk to human health under normal circumstances.
it is used
The use of chloroform as an anesthetic dates back to 1847, but concerns about its safety were soon raised. In 1848, a patient died of her heart beating rapidly and irregularly while she was anesthetized, and continued use only cemented the link between chemical and cardiac events. By the early 20th century, the use of chloroform was in decline and by the 20th century it was abandoned in favor of safer and cheaper alternatives. Today, safer anesthetics such as halothane, isoflurane and sevoflurane and others are used. When a less expensive alternative is required, as is the case in some impoverished nations, ether, an older anesthetic, is often preferred.
Today, the major use of chloroform is in the production of polytetrafluoroethylene (PTFE), a relatively heat-resistant plastic known for its use as a non-stick coating for pots and pans. The compound is first reacted with hydrofluoric acid to form chlorodifluoromethane, a compound used as a refrigerant and propellant for aerosol cans. This use has been phased out in many countries, due to its effects on the ozone layer, but its production is still an important step in the production of PTFE.
In the laboratory, trichloromethane is often used as a solvent, as it is stable, relatively non-reactive, and dissolves many organic compounds. It is very effective in extracting substances from plant material and is used in this way in the pharmaceutical industry to extract drugs and drug precursors from plants. It can also be employed in analytical chemistry to isolate compounds from samples and is used in the synthesis of many organic chemicals.
Health effects
The anesthetic effects of chloroform are well known and are due to inhibition of central nervous system activity. Inhaling the vapor can quickly render you unconscious, but a very large dose can be fatal. The chemical also affects the activity of other major organs, including the heart, making it dangerous as an anesthetic. It is considered moderately toxic — in terms of acute effects — if ingested, but a dose of 0.35 fluid ounces (10 milliliters) can be fatal in humans.
Long-term exposure to relatively low concentrations of trichloromethane can have a variety of adverse effects, especially on the liver and kidneys. There may be a cancer risk associated with exposure to this chemical. While there is no conclusive evidence of a link to human cancer, animal tests have shown that chloroform causes liver and kidney tumors and in the United States the Environmental Protection Agency (EPA) has classified it as “probable”. carcinogenic to humans”. Exposure is most likely to occur in an industrial or laboratory setting, but small amounts are present in the air and water. Because it does not react with many naturally occurring substances, it can take a long time to degrade and can accumulate in groundwater.
Another potential risk in handling and storing chloroform is the formation of the highly toxic gas, phosgene, which was used as a chemical weapon during World War I. In the presence of light, trichloromethane reacts with oxygen in the air to produce this gas. For this reason it is stored in dark glass bottles.
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