Chloromethane

Chloromethane
Names
IUPAC name
Chloromethane[1]
Other names
  • Refrigerant-40
  • R-40[2]
  • Methyl chloride[2]
  • Monochloromethane[2]
Identifiers
3D model (JSmol)
1696839
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.744
EC Number 200-817-4
24898
KEGG
MeSH Methyl+Chloride
RTECS number PA6300000
UNII
UN number 1063
Properties
CH3Cl
Molar mass 50.49 g·mol−1
Appearance Colorless gas
Odor Faint, sweet odor[3]
Density 1.003 g/mL (-23.8 °C, liquid)[2]2.3065 g/L (0 °C, gas)[2]
Melting point −97.4 °C (−143.3 °F; 175.8 K)[2]
Boiling point −23.8 °C (−10.8 °F; 249.3 K)[2]
5.325 g L−1
log P 1.113
Vapor pressure 506.09 kPa (at 20 °C (68 °F))
940 nmol Pa−1 kg−1
-32.0·10−6 cm3/mol
Structure
Tetragonal
Tetrahedron
1.9 D
Thermochemistry
234.36 J K−1 mol−1
−83.68 kJ mol−1
−764.5–−763.5 kJ mol−1
Hazards
Main hazards carcinogen
Safety data sheet See: data page
GHS pictograms
GHS signal word DANGER
H220, H351, H373
P210, P281, P410+403
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propaneHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
4
2
0
Flash point −20 °C (−4 °F; 253 K)[2]
625 °C (1,157 °F; 898 K)[2]
Explosive limits 8.1%-17.4%[3]
Lethal dose or concentration (LD, LC):
1800 mg/kg (oral, rat)[2]
5.3 mg/L/4 h (inhalation, rat)[2]
72,000 ppm (rat, 30 min)
2200 ppm (mouse, 6 hr)
2760 ppm (mammal, 4 hr)
2524 ppm (rat, 4 hr)[4]
20,000 ppm (guinea pig, 2 hr)
14,661 ppm (dog, 6 hr)[4]
US health exposure limits (NIOSH):
PEL (Permissible)
 TWA 100 ppm C 200 ppm 300 ppm (5-minute maximum peak in any 3 hours)[3]
REL (Recommended)
 Ca[3]
IDLH (Immediate danger)
 Ca [2000 ppm][3]
Related compounds
Related alkanes
Related compounds
 2-Chloroethanol
Supplementary data page
Refractive index (n),
Dielectric constant (εr), etc.
Thermodynamic
data
 Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is ☑Y☒N ?)
Infobox references

Chloromethane, also called methyl chloride, Refrigerant-40, 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 mildly sweet odor. 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.

Occurrence

Chloromethane is the most abundant organohalogen, anthropogenic or natural, in the atmosphere. It is a constituent of tobacco smoke.[5]

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.[6][7] An extensive study of 30 species of polar macroalgae revealed the release of significant amounts of CH3Cl in only Gigartina skottsbergii and Gymnogongrus antarcticus.[8]

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.[9] 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 crystallinum), each of which is a known CH3Cl producer.[9][10]

Interstellar detections

Chloromethane has been detected in the low-mass Class 0 protostellar binary, IRAS 16293–2422, using the Atacama Large Millimeter Array (ALMA). It was also detected in the comet 67P/Churyumov–Gerasimenko (67P/C-G) using the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument on the Rosetta spacecraft. [11] The detections reveal that chloromethane can be formed in star forming regions before planets or life is formed.

Freon-40 has been detected in Space.[12]

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 (662 °F).

A smaller amount of chloromethane is produced by heating a mixture of methane and chlorine to over 400 °C (752 °F). However, this method also results in more highly chlorinated compounds such as dichloromethane, chloroform, and carbon tetrachloride and is usually only used when these other products are also desired.

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. Exposure may cause drowsiness, dizziness, or confusion and difficulty breathing, walking or speaking may occur. At higher concentrations, paralysis, seizures, and coma can result.

In case of ingestion, nausea and vomiting may occur. Skin contact, when in the form of a refrigerated liquid, may result in frostbite. Contact with the eyes may result in dim vision, and 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.

References

  1. ↑ "Methyl Chloride - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Retrieved 23 June 2012.
  2. 1 2 3 4 5 6 7 8 9 10 11 Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  3. 1 2 3 4 5 "NIOSH Pocket Guide to Chemical Hazards #0403". National Institute for Occupational Safety and Health (NIOSH).
  4. 1 2 "Methyl chloride". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  5. ↑ Talhout, Reinskje; Schulz, Thomas; Florek, Ewa; Van Benthem, Jan; Wester, Piet; Opperhuizen, Antoon (2011). "Hazardous Compounds in Tobacco Smoke". International Journal of Environmental Research and Public Health. 8 (12): 613–628. doi:10.3390/ijerph8020613. ISSN 1660-4601. PMC 3084482. PMID 21556207.
  6. ↑ Scarratt MG, Moore RM (1996). "Production of Methyl Chloride and Methyl Bromide in Laboratory Cultures of Marine Phytoplankton". Mar Chem. 54 (3–4): 263. doi:10.1016/0304-4203(96)00036-9.
  7. ↑ Scarratt MG, Moore RM (1998). "Production of Methyl Bromide and Methyl Chloride in Laboratory Cultures of Marine Phytoplankton II". Mar Chem. 59 (3–4): 311. doi:10.1016/S0304-4203(97)00092-3.
  8. ↑ Laturnus F (2001). "Marine Macroalgae in Polar Regions as Natural Sources for Volatile Organohalogens". Environ Sci Pollut Res. 8 (2): 103. doi:10.1007/BF02987302.
  9. 1 2 Ni X, Hager LP (1998). "cDNA Cloning of Batis maritima Methyl Chloride Transferase and Purification of the Enzyme". Proc Natl Acad Sci USA. 95 (22): 12866–71. doi:10.1073/pnas.95.22.12866. PMC 23635. PMID 9789006.
  10. ↑ Ni X, Hager LP (1999). "Expression of Batis maritima Methyl Chloride Transferase in Escherichia coli". Proc Natl Acad Sci USA. 96 (7): 3611–5. doi:10.1073/pnas.96.7.3611. PMC 22342. PMID 10097085.
  11. ↑ https://www.eso.org/public/images/eso1732e/
  12. ↑ "ALMA and Rosetta Detect Freon-40 in Space - Dashing Hopes that Molecule May be Marker of Life". www.eso.org. Retrieved 3 October 2017.
  • International Chemical Safety Card 0419
  • "NIOSH Pocket Guide to Chemical Hazards #0403". National Institute for Occupational Safety and Health (NIOSH).
  • Data sheet at inchem.org
  • Toxicological information
  • Information about chloromethane
  • Concise International Chemical Assessment Document 28 on chloromethane
  • IARC Summaries & Evaluations Vol. 71 (1999)
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.