Chloroform

OVERVIEW

Chloroform (KLOR-oh-form) is a clear, colorless, flammable, volatile liquid with a characteristic odor and a sweet taste. It was discovered almost simultaneously in 1831 by American chemist Samuel Guthrie (1782–1848), French chemist Eugene Soubeiran (1797–1858), and German chemist Justus von Liebig (1803–1873). The chemical structure of the compound was determined by French chemist Jean-Baptiste-André Dumas (1800–1884), who suggested its modern name of chloroform in 1834 or 1835. The compound's anesthetic effects on animals were first observed by French physiologist Marie Jean-Pierre Flourens (1794–1867) in 1847.

KEY FACTS

OTHER NAMES:

Trichloromethane, trichloroform, methane trichloride, methenyl trichloride, methyl trichloride

FORMULA:

CHCl₃

ELEMENTS:

Carbon, hydrogen, chlorine

COMPOUND TYPE:

Halogenated hydrocarbon, alkyl halide (organic)

STATE:

Liquid

MOLECULAR WEIGHT:

119.38 g/mol

MELTING POINT:

−63.41°C (−82.14°F)

BOILING POINT:

61.17°C (142.1°F)

SOLUBILITY:

Slightly soluble in water; soluble in ethyl alcohol, ether, acetone, benzene, and other organic solvents

The potential value of chloroform as an anesthetic for humans was immediately evident. In Great Britain, Liverpool chemist David Waldie (1813–1889) suggested to a surgeon friend of his, Sir James Young Simpson (1811–1870), that he might try using chloroform instead of ether to ease the pain of childbirth with his patients. On the evening of November 4, 1847, Simpson and two physician friends experimented with chloroform to test its effects and all three passed out. Simpson was convinced of chloroform's value as an anesthetic and began using it in his medical practice. He did this over the objections of many clergymen of the era who believed that women should suffer the pain of childbirth because of Eve's actions in the Garden of Eden, as described in the Bible. The use of chloroform as a painkiller soon spread widely throughout Great Britain and other countries of the world.

In the twenty-first century, chloroform has been almost entirely replaced as an anesthetic by other compounds that are more effective and have fewer undesirable side effects. The compound is now used almost exclusively for the production of hydrochlorofluorocarbons (HCFCs), compounds developed to replace chlorofluorocarbons (CFCs) that have been banned because of their harmful effects on Earth's ozone layer.

HOW IT IS MADE

Chloroform is produced commercially by the reaction between chlorine gas and methane gas. In this reaction, each of the four hydrogens in methane is replaced, one at a time, by chlorine atoms. The reaction must be carefully controlled, therefore, to ensure that maximum amounts of the desired product (chloroform, in this case) are obtained.

Chloroform can also be produced in the reaction between acetone and bleaching powder (CaOCl₂) in the presence of sulfuric acid (H₂SO₄): 2CH₃COCH₃ + 6CaOCl₂ → 2CHCl₃ + (CH₃COO)₂Ca + 3CaCl₂ + 2Ca(OH)₂.

Interesting Facts

• The debate over the use of chloroform as an anesthetic during childbirth was largely resolved in 1853 when Queen Victoria (1819–1901) chose to have the procedure during the birth of her son Prince Leopold (1853–1884).
• Chloroform is recommended for the removal of lipstick stains.
• At one time, chloroform was used internally (usually in small doses) to treat a variety of medical problems, including cholera, gonorrhea, colic, cramps, spasms, and convulsions. Improper doses led to problems that were more serious that those being treated, including coma and death.
• Chloroform was once used in a number of consumer and household products, including toothpastes, cough syrups, and skin ointments. Its use for these purposes was banned in the United States in 1976.

COMMON USES AND POTENTIAL HAZARDS

In the early twenty-first century, more than 90 percent of the chloroform produced in the United States is used in the preparation of hydrochlorofluorocarbons (HCFCs). HCFCs are compounds consisting of carbon, hydrogen, chlorine, and fluorine. They were developed in the 1980s to replace the chlorofluorocarbons (CFCs) that, at the time, were widely used for a number of industrial applications. Replacing CFCs had become necessary because they were also destroying the ozone layer in the stratosphere that protects plants and animals on Earth's surface from harmful ultraviolet radiation.

Chloroform is used to make one specific HCFC known as HCFC-22. HCFC-22 is also known as Freon 22, halocarbon 22, fluorocarbon 22, or R22. By 2003, an estimated 600 million metric tons (660 million short tons) of chloroform were being used in the United States for all commercial purposes. Of the HCFC-22 produced, about 70 percent was being used as a refrigerant, while the remaining 30 percent went for the synthesis of polymers.

In addition to its use in the production of HCFC-22, chloroform has a number of other minor uses, including:

• As a solvent for fats, oils, waxes, rubber, and a number of pharmaceuticals;
• In the manufacture of certain dyes and pesticides;
• As a cleansing agent in various industrial operations;
• In fire extinguishing systems;
• As a glue for methyl methacrylate products; and
• As a laboratory reagent.

Words to Know

ANESTHETIC

A substance that is used to temporarily deaden the feeling in a part of the body or to make a person unconscious.

CARCINOGEN

A substance that causes cancer in humans or other animals.

POLYMER

A compound consisting of very large molecules made of one or two small repeated units called monomers.

VOLATILE

Able to turn to vapor easily at a relatively low temperature.

Long-term prospects for chloroform are not very promising since the production of HCFCs is scheduled to be phased out over time. Although they have less serious effects on ozone than do the CFCs, they are still regarded as a threat and their use has been restricted under provisions of the Montreal Protocol on Substances that Deplete the Ozone Layer. The U.S. Environmental Protection Agency plans to ban the use of HCFC-22 under the Protocol by 2010.

Chloroform is an irritant to the skin, eyes, and respiratory system. Moderate, short-term exposure may cause redness, pain, and dryness of the skin; redness and pain in the eyes; and coughing, nausea, headache, dizziness, drowsiness, vomiting, abdominal pain, and unconsciousness. At higher doses and longer exposure, chloroform is believed to cause serious damage to the liver and kidneys. It is also thought to be a carcinogen.

FOR FURTHER INFORMATION

"Chloroform." 11th Report on Carcinogens. National Toxicology Program. http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s038chlo.pdf (accessed on December 29, 2005).

"Chloroform." International Programme on Chemical Safety. http://www.inchem.org/documents/ehc/ehc/ehc163.htm (accessed on December 29, 2005).

"Occupational Safety and Health Guideline for Chloroform." Occupational Safety &Health Administration. http://www.osha.gov/SLTC/healthguidelines/chloroform/recognition.html (accessed on December 29, 2005).

Stratmann, Linda. Chloroform: The Quest for Oblivion. Phoenix Mill, UK: Sutton Publishing Co., 2003.

"ToxFAQs™ for Chloroform." Agency for Toxic Substances and Disease Registry. http://www.atsdr.cdc.gov/tfacts6.html (accessed on December 29, 2005).

See AlsoCarbon Tetrachloride

Chloroform

Chloroform is another name for the colorless, dense, liquid chemical compound trichloromethane. It is nonflammable and has a pleasant odor and a burning, sweet taste. Chloroform is about 40 times as sweet as sugar. Nearly insoluble (unable to be dissolved) in water, chloroform easily dissolves in alcohol, ether, acetone, gasoline, and other organic solvents. It can be prepared by the chlorination of ethyl alcohol or of methane. Once made from acetone and bleaching powder, chloroform is now prepared by the photochemical reaction of methane with chlorine.

Chloroform used for industrial purposes is usually made by the action of iron and acid on carbon tetrachloride. It is important as a solvent for gums, fats, resins, elements like sulfur and iodine, and many other organic compounds. Chloroform is also used to extract and purify penicillin.

Anesthetic Chloroform

Chloroform was popular as an anesthetic from the mid-1800s to around 1900, but it was found to cause death from paralysis of the heart in one patient in about 3,000. It also depresses most of the body's other organs, including the blood vessels, liver, pancreas, and kidneys. It is toxic to the liver. Oxygen-gas mixtures (oxygen with nitrous oxide, for example) regained use in anesthesia after 1900, and chloroform was replaced by safer compounds after about 1940. Years ago, chloroform was widely used in cough syrups, liniments, sedatives, and pain relievers. More recently, it has been listed as a carcinogen by the U.S. Environmental Protection Agency and been banned for use in drug, cosmetic, and food products since 1976.

The compound was discovered in 1831 by scientists in three different countries working at the same time: Samuel Guthrie (1782-1848) of the United States, Eugene Soubeiran (1797-1858) of France, and Justus von Liebig of Germany. (Guthrie, an American chemist and physician, also introduced Edward Jenner's vaccination technique to the United States.) M. J. Dumas of Paris described the composition of the new liquid and gave it the name "chloroform" in 1834 or 1835. The Frenchman Marie-Jean-Pierre Flourens (1794-1867) noted the anesthetic, but toxic, effect of chloroform on animals in March 1847.

Simpson Discovers Chloroform's Potency

Sir James Young Simpson, an eminent Scottish obstetrician, introduced the medical use of chloroform as an anesthetic in Edinburgh, Scotland, in November 1847. Earlier that year, Simpson had begun using ether to relieve the pain of childbirth, but was dissatisfied with some of ether's drawbacks, such as its disagreeable smell, the large quantities required, and the lung irritation it caused. Ether was also explosive, which was a problem for doctors who often worked by candlelight in rooms heated by fireplaces. A Liverpool chemist, David Waldie, suggested that Simpson try chloroform. On the evening of November 4,1847, Simpson and two doctor friends inhaled some chloroform and, after feeling very happy and talkative, promptly passed out. Impressed with chloroform's potency and rapid effects, Simpson immediately began using it in his obstetrical practice. The first baby bom to a mother who received chloroform for pain was named Anaesthesia.

Scottish clergymen quickly objected to this use of anesthesia, insisting the pain of childbirth was ordained by God. Simpson countered by citing the biblical account of the deep sleep cast on Adam when God took the first man's rib and used it to make Eve. The argument continued until 1853, when Queen Victoria (ruler of England from 1837-1901) chose to be chlo-roformed for the birth of her son Prince Leopold (1853-1884). This event quieted the clergy and made chloroform the most fashionable anesthetic—especially in England—for the next 50 years.

Although chloroform did carry some risk of heart failure, it was more pleasant to take and more powerful than ether. Queen Victoria's anesthetist, Dr. John Snow (1813-1858), developed an inhaler to regulate the amount of chloroform administered to a patient so that he or she felt no pain but remained conscious.

[See also Anesthesia ]

Chloroform

Chloroform is the common name of the organic chemical compound whose chemical formula is HCCl₃ . It is also known as methyl trichloride. The molecule of trichloromethane, as it is also called, consists of a central carbon (C) atom bonded to a hydrogen (H) atom and three chlorine (Cl) atoms. It is a member of the group called trihalomethanes, which are known environmental pollutants.

Chloroform is a nonflammable colorless liquid at room temperature (boiling point 141.8°F [61°C]) that has a heavy sweet odor and taste. It is very volatile and cannot be mixed well with water. However, it does mix well with other hydrocarbons, so one of its uses is as a solvent or cleaner to dissolve other organic substances like gums, waxes, resins, and fats. In addition, chloroform is used in the industrial synthesis of the non-stick coating called Teflon^® (polytetrafluoroethylene), which is an organic polymer. However, in the past, the primary use for chloroform was as a general anesthetic.

The compound was first synthesized in the laboratory in 1831 simultaneously by Justus von Liebig (1803–1873) in Germany and by Eugene Soubeiran (1797–1858) in France using different procedures. Samuel Guthrie (1782–1848), in the United States, also discovered chloroform in that same year.

Chloroform was originally used to calm people suffering from asthma. In 1847, British physician Sir James Young Simpson (1811–1870), a professor of midwifery at the University of Edinburgh, began using chloroform as an anesthetic to reduce pain during childbirth. From this initial experiment, chloroform began to be used as general anesthesia in medical procedures throughout the world. The use of chloroform in this application was eventually abandoned because of its harmful side effects on the heart and liver.

Chloroform has commonly been used as a solvent in the manufacture of pesticides, dyes, and drugs. The use of the chemical in this manner was important in the preparation of penicillin during World War II. Chloroform was used as a sweetener in various cough syrups and to add flavor bursts to toothpaste and mouthwash. Its pain relieving properties were incorporated into various liniments and toothache medicines. The chemical was also used in photographic processing and dry cleaning. All of these applications for chloroform were stopped by the U.S. Federal Drug Administration (FDA) in 1976 when the compound was discovered to cause cancer in laboratory mice. Today, chloroform is a key starting material for the production of chemicals used in refrigerators and air conditioners.

Chloroform

Chloroform is the common name of the organic compound whose chemical formula is HCCl 3. The molecule of trichloromethane, as it is also called, consists of a central carbon atom bonded to a hydrogen atom and three chlorine atoms . Chloroform is a nonflammable colorless liquid (boiling point 141.8°F [61°C]) that has a heavy sweet odor and taste . The compound was first prepared in 1831 simultaneously by Justus von Liebig (1803-1873) in Germany and by Eugene Soubeiran (1797-1858) in France using different procedures. Samuel Guthrie (1782-1848), in the United States, also discovered chloroform in that same year.

Chloroform was originally used to calm people suffering from asthma . In 1847, James Y. Simpson, a Professor of Midwifery at the University of Edinburgh, began using chloroform as an anesthetic to reduce pain during childbirth. From this initial experiment, chloroform began to be used as general anesthesia in medical procedures throughout the world. The use of chloroform in this application was eventually abandoned because of its harmful side effects on the heart and liver.

Chloroform has commonly been used as a solvent in the manufacture of pesticides , dyes, and drugs. The use of the chemical in this manner was important in the preparation of penicillin during World War II. Chloroform was used as a sweetener in various cough syrups and to add flavor "bursts" to toothpaste and mouthwash. Its pain relieving properties were incorporated into various liniments and toothache medicines. The chemical was also used in photographic processing and dry cleaning. All of these applications for chloroform were stopped by the Federal Drug Administration (FDA) in 1976, when the compound was discovered to cause cancer in laboratory mice . Today, chloroform is a key starting material for the production of chemicals used in refrigerators and air conditioners.

chlo·ro·form / ˈklôrəˌfôrm/ • n. a colorless, volatile, sweet-smelling liquid, CHCl₃, used as a solvent and formerly as a general anesthetic.• v. [tr.] render (someone) unconscious with this substance.