Chloroform

• Trichloromethane (IUPAC)
• Chloretherid
• Methenyl
• Methinchlorid
• TCM
• R20

Colorless liquid with a sweet odor

Liquid

1.48 g · cm -3 ( 20 ° C)

-63 ° C

61 ° C

209 hPa ( 20 ° C)

Poorly in water ( 8.2 g · l-1 at 20 ° C)

1.04 (2 ) D ( 3.5 × 10-30 C · m)

1.445 ( n D 20 )

Attention

0.5 ml · m-3

-134.1 KJ / mol

Template: Infobox chemical / molecular formula search available

Chloroform ( trichloromethane systematic name ) is a chlorinated hydrocarbon with molecular formula CHCl3.

History

Chloroform was produced independently of each other by Samuel Guthrie, Justus von Liebig and Eugène Soubeiran in 1831. After its narcotic effect already in 1842 by the British physician Robert Mortimer Glover and 1847 by the French physiologist Marie Jean Pierre Flourens and the Scottish obstetrician James Young Simpson was recognized, it was the merit of the latter, chloroform a year later in the medical introduce practice and countless patients to avoid surgery pain.

Because of that surgical procedure, the use of this narcotic was of great importance for the whole surgical activity: So the sick were afraid long before an operation, the impending pain and then came often been confused on the operating table. There they were fixed according to certain prescribed for each particular operation methods so that they not by interfering movements doctors disabled during the painful procedure. During the procedure even then the most important requirement was the speed, which is often the accuracy, cleanliness and thoroughness were killed.

Production

Industrially chloroform is formed by heating chlorine with methane or methyl chloride at 400-500 ° C.. At this temperature is gradually radical substituted up to tetrachloromethane:

In this case, first methane reacts with chlorine to form hydrogen chloride to methyl chloride, then to dichloromethane, trichloromethane and finally tetrachloromethane. The result of the process is a mixture of the four chloromethanes, which can be separated by distillation. Technical grade chloroform industrially produced also contains bromine and ethane derivatives (for example, bromochloromethane, bromodichloromethane, 1,2- dichloroethane) as an impurity as well as ethanol ( <1%) or pentenes (<0.1 %), which are added as a stabilizer artificially to intercept the generated during storage in air and light phosgene.

Laboratory chloroform can be represented by acetone, by haloform reaction from the reaction of sodium hypochlorite.

Properties

Trichloromethane is a colorless, non-flammable, volatile liquid of a sweet smell. The melting point is -63 ° C. The boiling point under normal pressure at 61 ° C. It has a greater density than water and is only slightly soluble therein.

Chloroform is decomposed photochemically by oxygen under the influence of light, thereby arise phosgene, chlorine and hydrogen chloride. Commercially available chloroform containing 0.5-1.0% ethanol as a stabilizer to chemically trap arising phosgene.

The vapors of chloroform cause unconsciousness and lift the sensation of pain on. Because of the toxic effects on the heart, liver and other internal organs chloroform is no longer used today as an anesthetic. It also is suspected to be carcinogenic.

Use

Chloroform is used primarily as a solvent for the production of chlorofluorocarbons (CFCs ).

In the chemical synthesis, it is used for the preparation of dichlorocarbene ( in the presence of bases). Friedel -Crafts alkylation with benzene obtained triphenylmethane.

Deuterated chloroform ( CDCl3 ), also known as deuterochloroform, found in the nuclear magnetic resonance spectroscopy (NMR) as a solvent used.

In the determination of the microbial biomass in soil fumigation using chloroform extraction is exploited that causes cell lysis chloroform.

Legal provisions

The use of chloroform is generally prohibited in food-producing animals in accordance with EU MRLs regulation for food of animal origin in the European Union.