Chloromethane


Chloromethane
Chloromethane
Identifiers
CAS number 74-87-3 YesY
PubChem 6327
ChemSpider 6087 YesY
UNII A6R43525YO YesY
EC number 200-817-4
KEGG C19446 N
ChEBI CHEBI:36014 YesY
ChEMBL CHEMBL117545 YesY
RTECS number PA6300000
Jmol-3D images Image 1
Properties
Molecular formula CH3Cl
Molar mass 50.49 g/mol
Appearance Colorless gas with a faint sweet odor
Density 2.22 kg/m3 (0 °C)
Melting point

−97.7 °C (176 K) (-143.9 °F)

Boiling point

-24.2 °C (249 K) (-11.6 °F)

Solubility in water 5.325 g/l (25 °C)
log P 0.91
Vapor pressure 490 kPa (20 °C) ; 71 PSI (68°F)
Structure
Molecular shape Tetrahedral
Hazards
MSDS External MSDS
EU classification Extremely flammable (F+), Harmful (Xn), Carc. Cat. 3
R-phrases R12, R40, R48/20
S-phrases S9, S16, S33
NFPA 704
NFPA 704.svg
4
2
0
Flash point -46 °C
Autoignition
temperature
625 °C
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Chloromethane, also called methyl chloride, R-40 or HCC 40, is a chemical compound of the group of organic compounds called haloalkanes. It was once widely used as a refrigerant. It is a colorless extremely flammable gas with a minorly sweet odor, which is, however, detected at possibly toxic levels. Due to concerns about its toxicity, it is no longer present in consumer products. Chloromethane was first synthesized by the French chemists Jean-Baptiste Dumas and Eugene Peligot in 1835 by boiling a mixture of methanol, sulfuric acid, and sodium chloride. This method is similar to that used today.

Contents

Occurrence

Chloromethane is the most abundant organohalogen – anthropogenic or natural – in the atmosphere.

Marine

Laboratory cultures of marine phytoplankton (Phaeodactylum tricornutum, Phaeocystis sp., Thalassiosira weissflogii, Chaetoceros calcitrans, Isochrysis sp., Porphyridium sp., Synechococcus sp., Tetraselmis sp., Prorocentrum sp., and Emiliana huxleyi) produce CH3Cl, but in relatively insignificant amounts.[1][2] An extensive study of 30 species of polar macroalgae revealed the release of significant amounts of CH3Cl in only Gigartina skottsbergii and Gymnogongrus antarcticus.[3]

Biogenesis

The salt marsh plant Batis maritima contains the enzyme methyl chloride transferase that catalyzes the synthesis of CH3Cl from S-adenosine-L-methionine and chloride.[4] This protein has been purified and expressed in E. coli, and seems to be present in other organisms such as white rot fungi (Phellinus pomaceus), red algae (Endocladia muricata), and the ice plant (Mesembryanthemum crystallium), each of which is a known CH3Cl producer.[5][6]

Production

Large amounts of chloromethane are produced naturally in the oceans by the action of sunlight on biomass and chlorine in sea foam. However, all chloromethane that is used in industry is produced synthetically.

Most chloromethane is prepared by reacting methanol with hydrogen chloride, according to the chemical equation

CH3OH + HCl → CH3Cl + H2O

This can be carried out either by bubbling hydrogen chloride gas through boiling methanol with or without a zinc chloride catalyst, or by passing combined methanol and hydrogen chloride vapors over an alumina catalyst at 350 °C.

A smaller amount of chloromethane is produced by heating a mixture of methane and chlorine to over 400 °C. However, this method also results in more highly chlorinated compounds such as methylene chloride and chloroform and is usually only used when these other products are also desired.

Further reaction of chloromethane with chlorine can produce dichloromethane, trichloromethane (known as chloroform) and tetrachloromethane (also known as carbon tetrachloride).

Uses

Chloromethane was a widely used refrigerant, but its use has been discontinued due to its toxicity and flammability. Chloromethane was also once used for producing lead-based gasoline additives (tetramethyllead).

The most important use of chloromethane today is as a chemical intermediate in the production of silicone polymers. Smaller quantities are used as a solvent in the manufacture of butyl rubber and in petroleum refining.

Chloromethane is employed as a methylating and chlorinating agent in organic chemistry. It is also used in a variety of other fields: as an extractant for greases, oils and resins, as a propellant and blowing agent in polystyrene foam production, as a local anesthetic, as an intermediate in drug manufacturing, as a catalyst carrier in low-temperature polymerization, as a fluid for thermometric and thermostatic equipment, and as a herbicide.

Safety

Inhalation of chloromethane gas produces central nervous system effects similar to drug intoxication. Victims may feel drowsy, dizzy, or confused and have difficulty breathing, with gasping and choking, walking or speaking. At higher concentrations, paralysis, seizures, and coma may result.

In case of ingestion nausea and vomiting may result. Skin contact when in the form of a refrigerated liquid may result in frostbite. Contact with eyes may result in dim vision, widely dilated pupils that react slowly to changes in light.

Chronic exposure to chloromethane has been linked to birth defects in mice. In humans, exposure to chloromethane during pregnancy may cause the fetus' lower spinal column, pelvis, and legs to form incorrectly, but this has not been conclusively demonstrated.

In 1997, a re-investigation of Boston's Cocoanut Grove nightclub fire in 1942 cited a chloromethane leak from a refrigerator as a major cause of that disaster.

References

  1. ^ Scarratt MG, Moore RM (1996) Production of Methyl Chloride and Methyl Bromide in Laboratory Cultures of Marine Phytoplankton. Mar Chem 54: 263
  2. ^ Scarratt MG, Moore RM (1998) Production of Methyl Bromide and Methyl Chloride in Laboratory Cultures of Marine Phytoplankton II. Mar Chem 59: 311
  3. ^ Laturnus F (2001) Marine Macroalgae in Polar Regions as Natural Sources for Volatile Organohalogens. Environ Sci Pollut Res 8: 103
  4. ^ Ni X, Hager LP (1998) cDNA Cloning of Batis maritima Methyl Chloride Transferase and Purification of the Enzyme. Proc Natl Acad Sci USA 95: 12866
  5. ^ Ni X, Hager LP (1998) cDNA Cloning of Batis maritima Methyl Chloride Transferase and Purification of the Enzyme. Proc Natl Acad Sci USA 95: 12866
  6. ^ Ni X, Hager LP (1999) Expression of Batis maritima Methyl Chloride Transferase in Escherichia coli. Proc Natl Acad Sci USA 96: 3611

External links


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Look at other dictionaries:

  • Chlorométhane — Général Nom IUPAC …   Wikipédia en Français

  • Chloromethane — Chlorométhane Chlorométhane Général Nom …   Wikipédia en Français

  • chlorométhane — ● chlorométhane nom masculin Synonyme de chlorure de méthyle. ● chlorométhane (synonymes) nom masculin Synonymes : chlorure de méthyle …   Encyclopédie Universelle

  • chloromethane — chlormetanas statusas T sritis chemija formulė CH₃Cl atitikmenys: angl. chloromethane; methyl chloride rus. хлористый метил; хлорметан ryšiai: sinonimas – metilchloridas …   Chemijos terminų aiškinamasis žodynas

  • chloromethane — /klawr euh meth ayn, klohr /, n. See methyl chloride. [1870 75; CHLORO 2 + METHANE] * * * …   Universalium

  • chloromethane — noun Any chlorinated derivative of methane, but especially CHCl (methyl chloride) once used as a refrigerant …   Wiktionary

  • chloromethane — A refrigerant with anesthetic properties when inhaled; it hydrolyzes to methanol. SYN: methyl chloride. * * * chlo·ro·meth·ane .klōr ō meth .ān, .klȯr n METHYL CHLORIDE …   Medical dictionary

  • chloromethane — n. chemical substance used as an anaesthetic and in refrigeration …   English contemporary dictionary

  • chloromethane — chlo·ro·methane …   English syllables

  • chloromethane — /klɔroʊˈmiθeɪn/ (say klawroh meethayn) noun a colourless gas, methyl chloride, CH3Cl …   Australian English dictionary


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