chloroform(redirected from Freon 20)
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trichloromethane(trī'klôrōmĕth`ān), CHCl3, volatile, colorless, nonflammable liquid that has a sweetish taste and a somewhat pungent odor; it boils at 61.7°C;. It dissolves freely in ethanol and ether but does not mix with water. Chloroform is produced by reaction of chlorine with ethanol and by the reduction of carbon tetrachloride with moist iron. It was once used as a general anesthetic in surgery but has been replaced by less toxic, safer anesthetics, such as ether. Chemically, it is employed as a solvent for fats, alkaloids, iodine, and other substances. When exposed to sunlight and air it reacts to form phosgenephosgene
, colorless poison gas, first used during World War I by the Germans (1915). When dispersed in air, the gas has the odor of new-mowed hay. The gas is highly toxic; when inhaled it reacts with water in the lungs to form hydrochloric acid and carbon monoxide.
..... Click the link for more information. , a poisonous gas.
(also trichloromethane), CHCl3, a colorless liquid, with a pungent odor and sweet burning taste. Chloroform has a boiling point of 61.15°C and a density of 1.488 g/cm3 (at 20°C). It is practically insoluble in water but is soluble in most organic solvents. In the light, it is slowly decomposed by atmospheric oxygen with the formation of phosgene, chlorine, hydrogen chloride, and formic acid; consequently, 1 percent ethyl alcohol is added as a stabilizer.
Many reactions of chloroform proceed through the intermediate formation of dichlorocarbene, :CCl2, for example, the synthesis of isocyanides by the reaction of chloroform with primary amines in the presence of alkalies and the reaction of chloroform with the alcoholates RONa, which leads to the formation of ortho esters.
Chloroform is produced by chlorination, for example, of methane, acetone, or alcohol. Considerable chloroform is used in industry in the production of the freon difluorochloromethane, CF2ClH; it is also used as a solvent.
Chloroform is an anesthetic. It exists in two types of preparations. The first is primarily for external use, in medical practice for massages and in histology as a tissue preservative and fixative; occasionally it is used internally in the form of drops to relieve certain symptoms, for example, nausea. The second type of chloroform preparation is used as an anesthetic; it is specially purified and has a strong anesthetizing effect and relatively high toxicity.