chloroform

Structural formula
Wedge line formula to clarify the geometry
General
Surname chloroform
other names
• Trichloromethane ( IUPAC )
• Chloroetheride
• Methenyl chloride
• Methine chloride
• TCM
• R-20
Molecular formula CHCl 3
Brief description

colorless liquid with a sweet odor

External identifiers / databases
 CAS number 67-66-3 EC number 200-663-8 ECHA InfoCard 100,000,603 PubChem 6212 Wikidata Q172275
properties
Molar mass 119.38 g mol −1
Physical state

liquid

density

1.48 g cm −3 (20 ° C)

Melting point

−63 ° C

boiling point

61 ° C

Vapor pressure
• 209 hPa (20 ° C)
• 321 hPa (30 ° C)
• 477 hPa (40 ° C)
solubility

poor in water (8 g l −1 at 20 ° C)

Dipole moment

1.04 (2) D (3.5 x 10 -30  C  ·  m )

Refractive index

1.445 (n D 20 )

safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary

danger

H and P phrases H: 302-331-315-319-351-361d-336-372
P: 261-281-305 + 351 + 338-311
MAK

DFG / Switzerland: 0.5 ml m −3 or 2.5 mg m −3

Global warming potential

20 (based on 100 years)

Thermodynamic properties
ΔH f 0

−134.1 kJ / mol

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Chloroform (systematic name trichloromethane ) is a chlorinated hydrocarbon with the empirical formula CHCl 3 .

history

Cartoon: The Effect of Chloroform on James Young Simpson and Friends (ca.1840s)

Chloroform was produced independently in 1831 by the American Samuel Guthrie , the German Justus Liebig and the French Eugène Soubeiran . Its physical and chemical properties as well as a molecular formula ("C 4 H 2 Ch 6 " or C 2 H 2 Cl 6 ) were first described by Jean-Baptiste Dumas in 1834. Dumas gave the substance, which Liebig still called "chlorine carbon", the name " Chloroform". After its narcotic effect had been recognized in animal experiments as early as 1842 by the British doctor Robert Mortimer Glover and in 1847 by the French physiologist Marie Jean Pierre Flourens and the Scottish doctor and obstetrician James Young Simpson , it was thanks to the latter that chloroform was added a year later to introduce the ether, which has been in use since the end of 1846, into medical practice to eliminate or alleviate birth pains. Simpson's friend, the surgeon and chemist David Waldie (* 1813 in Linlithgow) had probably already made an initial suggestion for the practical use of chloroform for surgical anesthesia.

The first documented death from anesthesia was chloroform anesthesia performed in 1848 on the patient Hanna Greener.

Obstetric pain relief with chloroform came against the resistance of the Anglican Church. Many clerics considered the agony of childbirth to be the just punishment for Eve's fall, that is, God's will. After John Snow in 1853, chloroform also successful in Queen Victoria had (head of the Church of England) used for anesthesia "à la Reine", it was initially the most widely used in Europe anesthetic . It was not until around 1890 that the use of ether was preferred again because of the undesirable side effects with frequent deaths due to anesthesia in chloroform anesthesia .

In view of the surgical procedures at that time, the use of this narcotic was of great importance for the entire surgical activity: the patients feared the impending pain long before an operation and often came to the operating table unsettled . There they were fixed in place using certain methods that had been drawn up for each particular operation so that they would not hinder the doctors with disruptive movements during the painful procedure. During the procedure itself, the most important requirement was speed, to which accuracy, cleanliness and thoroughness often fell victim.

Manufacturing

In industry, chloroform is produced by heating chlorine with methane or chloromethane to 400–500 ° C. At this temperature, radical substitution takes place up to carbon tetrachloride :

${\ displaystyle {\ ce {CH4 + Cl2 -> CH3Cl + HCl}}}$
${\ displaystyle {\ ce {CH3Cl + Cl2 -> CH2Cl2 + HCl}}}$
${\ displaystyle {\ ce {CH2Cl2 + Cl2 -> CHCl3 + HCl}}}$
${\ displaystyle {\ ce {CHCl3 + Cl2 -> CCl4 + HCl}}}$

Methane reacts with chlorine with the formation of hydrogen chloride first to form chloromethane, then further to dichloromethane , trichloromethane and finally to tetrachloromethane . The result of the process is a mixture of the four chloromethanes, which can be separated by distillation . Industrially produced chloroform of technical purity also contains bromine and ethane derivatives (e.g. bromochloromethane , bromodichloromethane , 1,2-dichloroethane ) as impurities, as well as ethanol (<1%) or pentenes (<0.1%), which are artificially added as a stabilizer in order to intercept the phosgene that is produced when stored in air and light .

Alternatively, chloroform can be obtained by photochlorination of methane. In the laboratory, chloroform can be represented by the reaction of sodium hypochlorite with acetone , a haloform reaction .

properties

Physical Properties

Trichloromethane is a colorless, non-flammable, volatile liquid with a sweet odor. The melting point is −63 ° C, the boiling point under normal pressure is 61 ° C. According to Antoine, the vapor pressure function results from log 10 (P) = A− (B / (T + C)) (P in bar, T in K) with A = 4.20772, B = 1233.129 and C = −40.953 in the temperature range from 215 to 334 K and with A = 4.56992, B = 1486.455 and C = −8.612 in the temperature range from 334.4 to 527 K. It has a greater density than water and is only slightly soluble in it. The miscibility with water is limited. As the temperature rises, the solubility of chloroform in water decreases or the solubility of water in chloroform increases.

 Solubilities between chloroform and water Temperature (in ° C) 0 9.5 19.6 29.5 39.3 49.2 59.2 Chloroform in water ( mass fraction in%) 1.02 0.93 0.82 0.79 0.74 0.77 0.79 Water in chloroform (mass fraction in%) 0.0365 0.0527 0.0661 0.0841 0.1108 0.1353 0.1672

The compound forms azeotropically boiling mixtures with a number of solvents . The azeotropic compositions and boiling points can be found in the following table. No azeotropes are with n -pentane , n -heptane , cyclohexane , benzene , toluene , n-propanol , i-butanol , carbon tetrachloride , diethyl ether , 1,4-dioxane , n-butyl acetate , acetic acid , acetonitrile , nitrobenzene , carbon disulfide and pyridine formed .

 Azeotropes with various solvents solvent water Methanol Ethanol 2-propanol acetone 2-butanone Content of chloroform in w% 97 87 93 96 78 17th boiling point in ° C 56 53 59 61 64 80 solvent Diisopropyl ether Tetrahydrofuran Methyl acetate Ethyl acetate n-hexane Content of chloroform in w% 36 66 77 28 83 boiling point in ° C 71 73 65 78 60

Chemical properties

Chloroform is photochemically decomposed by oxygen under the influence of light, producing phosgene , chlorine and hydrogen chloride . Commercially available chloroform contains 0.5–1.0% ethanol as a stabilizer to chemically intercept phosgene that is formed.

Its structure (CHX 3 ) forms a homologous series with fluoroform , bromoform and iodoform .

Reaction with acetone

Acetone and chloroform must not be mixed in higher concentrations because the presence of traces of alkaline substances can lead to a very violent reaction in which 1,1,1-trichloro-2-methyl-2-propanol (| α, α , α-trichloro- tert- butanol) is formed. For this reason, too, chlorinated and non-chlorinated solvent waste should be collected separately in the laboratory.

use

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

With alcoholic potash and ammonia , potassium cyanide is formed when heated . If primary amines are used instead of ammonia, isonitriles are obtained . With this reaction discovered by August Wilhelm von Hofmann , primary amines can also be qualitatively detected, because the isonitriles can be recognized by a strong and foul odor.

In chemical synthesis, it is used to produce dichlorocarbene (in the presence of bases). By Friedel-Crafts reaction with benzene obtained triphenylmethane .

The determination of microbial biomass in soil samples by means of chloroform fumigation extraction takes advantage of the fact that chloroform causes cell lysis .

safety instructions

The fumes of chloroform cause unconsciousness and lower the sensation of pain . Because of its toxic effects on the heart , liver and other internal organs , chloroform is no longer used as an anesthetic . It is also suspected of being carcinogenic .

Legal provisions

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

Deuterochloroform

Deuterated chloroform

Deuterated chloroform (empirical formula: CDCl 3 , CAS no .: 865-49-6), also called deuterochloroform , is used as a solvent in nuclear magnetic resonance spectroscopy (NMR).

The synthesis takes place by reacting the calcium salt of trichloroacetic acid with heavy water .

${\ displaystyle {\ ce {(Cl_3CCO_2) _2 Ca + D_2O -> 2 Cl_3CD + CaCO_3 + CO_2}}}$

The physical properties are slightly different from the non-deuterated compound:

• Melting point: -64 ° C
• Boiling point: 60.9 ° C
• Density: 1,500 g / ml (25 ° C)
• Refractive index: 1.444 (20 ° C)

literature

• Franz Hartmann: Contribution to the literature on the effect of chloroform . Ferber, Giessen 1855 ( digitized version )
• M. Rossberg; W. Lendle; G. Pfleiderer, A. Tögel; TR Torkelson, KK bag: Chloromethanes , in: Ullmanns Enzyklopädie der Technischen Chemie , Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 2012; doi : 10.1002 / 14356007.a06_233.pub3 .
• Albert Faulconer, Thomas Edward Keys: Chloroform. In: Foundations of Anesthesiology. 2 volumes, Charles C Thomas, Springfield (Illinois) 1965, Volume 1, pp. 442-481.

Individual evidence

1. Entry on trichloromethane in the GESTIS substance database of the IFA , accessed on November 12, 2017(JavaScript required) .
2. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Dipole Moments, pp. 9-58.
3. Data sheet chloroform from Sigma-Aldrich , accessed on July 19, 2010 ( PDF ).
4. Entry on chloroform in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
5. Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 67-66-3 or chloroform ), accessed on November 2, 2015.
6. G. Myhre, D. Shindell et al .: Climate Change 2013: The Physical Science Basis . Working Group I contribution to the IPCC Fifth Assessment Report. Ed .: Intergovernmental Panel on Climate Change . 2013, Chapter 8: Anthropogenic and Natural Radiative Forcing, pp. 24-39; Table 8.SM.16 ( PDF ).
7. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-19.
8. Chloroform in the Notable Names Database (English)
9. Justus Liebig: About the compounds that arise through the action of chlorine on alcohol, ether, oil-forming gas and spirit. In: Annals of Pharmacy. Volume 1, 1832, pp. 182-230 ( digitized in the Google book search).
10. ^ Jean-Baptiste-André Dumas: Recherches relatives à l'action du chlore sur l'alcool. In: L'Institut. Journal général des société et travaux scientifiques des la France et l'étranger. Volume 2, (April 5) 1834, pp. 106-108.
11. Jean-Baptiste-André Dumas: Investigation into the effect of chlorine on alcohol. In: Annals of Physics and Chemistry. New series, Volume 31, 1834, pp. 650-673 ( digitized on Gallica ).
12. ^ Albert Faulconer, Thomas Edward Keys: Chloroform. In: Foundations of Anesthesiology. 2 volumes, Charles C Thomas, Springfield (Illinois) 1965, Volume 1, pp. 442-481, here: pp. 442 f., 455-462.
13. ^ JY Simpson: On a new anesthetic agent, more efficient than sulfuric ether. In: Lancet. Volume 2, (November 20) 1847, p. 549 f. ( Digitized in the Google book search).
14. Ray J. Defalque, Amos J. Wright: The Discovery of Chloroform: Has David Waldie's Role Been Exaggerated? In: Anesthesiology. Volume 114, No. 4, 2011, pp. 1004-1005, doi: 10.1097 / ALN.0b013e31820ca94c .
15. www.annethousemuseum: to David Waldie .
16. Michael Heck, Michael Fresenius: Repetitorium Anaesthesiologie. Preparation for the anesthesiological specialist examination and the European diploma in anesthesiology. 3rd, completely revised edition. Springer, Berlin / Heidelberg / New York et al. 2001, ISBN 3-540-67331-8 , p. 803.
17. WDR1 - as of November 9, 2007 - 160 years ago: First delivery with chloroform anesthesia. Retrieved November 29, 2017.
18. Homepage Klinikum Dortmund General information on the history of anesthesia. Retrieved November 29, 2017.
19. ^ Rudolf Frey , Otto Mayrhofer , with the support of Thomas E. Keys and John S. Lundy: Important data from the history of anesthesia. In: R. Frey, Werner Hügin , O. Mayrhofer (Ed.): Textbook of anesthesiology and resuscitation. Springer, Heidelberg / Basel / Vienna 1955; 2nd, revised and expanded edition. With the collaboration of H. Benzer. Springer, Berlin / Heidelberg / New York 1971. ISBN 3-540-05196-1 , pp. 13–16, here: p. 14.
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22. Sigma-Aldrich: Chloroform .
23. Chemgapedia: Synthesis of Trichloromethane.
24. ^ Stull, DR: Vapor Pressure of Pure Substances. Organic and Inorganic Compounds in Ind. Eng. Chem. 39 (1947), pp. 517-540, doi: 10.1021 / ie50448a022 .
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30. External identifiers or database links for deuterochloroform : CAS number: 865-49-6, EC number: 212-742-4, ECHA InfoCard: 100.011.585 , PubChem : 71583 , ChemSpider : 64654 , Wikidata : Q1032539 .
31. ^ Preparation of chloroform-d , on prepchem.com.
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