Chloromethane

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Chloromethane
Stereo, skeletal formula of chloromethane with all explicit hydrogens added
Ball and stick model of chloromethane
Ball and stick model of chloromethane
Spacefill model of chloromethane
Spacefill model of chloromethane
Names
Preferred IUPAC name
Chloromethane[2]
Other names
  • Refrigerant-40
  • R-40[1]
  • Methyl chloride[1]
  • Monochloromethane[1]
Identifiers
3D model (
JSmol
)
1696839
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard
 100.000.744 Edit this at Wikidata
EC Number
  • 200-817-4
24898
KEGG
MeSH Methyl+Chloride
RTECS number
  • PA6300000
UNII
UN number 1063
  • InChI=1S/CH3Cl/c1-2/h1H3 checkY
    Key: NEHMKBQYUWJMIP-UHFFFAOYSA-N checkY
  • CCl
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)[1] 2.3065 g/L (0 °C, gas)[1]
Melting point −97.4 °C (−143.3 °F; 175.8 K)[1]
Boiling point −23.8 °C (−10.8 °F; 249.3 K)[1]
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
Std enthalpy of
formation
(ΔfH⦵298)
 −83.68 kJ mol−1
Std enthalpy of
combustion
(ΔcH⦵298)
 −764.5–−763.5 kJ mol−1
Hazards
GHS labelling:
GHS02: Flammable GHS08: Health hazard
Danger
H220, H351, H373
P210, P281, P410+P403
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 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. propaneInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
4
0
Flash point −20 °C (−4 °F; 253 K)[1]
625 °C (1,157 °F; 898 K)[1]
Explosive limits
 8.1%-17.4%[3]
Lethal dose or concentration (LD, LC):
150-180 mg/kg (oral, rat)[1]
5.3 mg/L/4 h (inhalation, rat)[1]
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]
NIOSH (US health exposure limits):
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
Chloromethane (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Chloromethane, also called methyl chloride, Refrigerant-40, R-40 or HCC 40, is an organic compound with the chemical formula CH3Cl. One of the haloalkanes, it is a colorless, sweet-smelling, flammable gas. Methyl chloride is a crucial reagent in industrial chemistry, although it is rarely present in consumer products,[5] and was formerly utilized as a refrigerant. Most chloromethane is biogenic.

Occurrence

Chloromethane is an abundant

organohalogen, anthropogenic or natural, in the atmosphere. Natural sources produce an estimated 4,100,000,000 kg/yr.[6]

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.[7][8] An extensive study of 30 species of polar macroalgae revealed the release of significant amounts of CH3Cl in only Gigartina skottsbergii and Gymnogongrus antarcticus.[9]

Biogenesis

The

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.[10][11]

Sugarcane and the emission of methyl chloride

In the sugarcane industry, the organic waste is usually burned in the power cogeneration process. When contaminated by chloride, this waste burns, releasing methyl chloride in the atmosphere.[12]

Interstellar detections

Chloromethane has been detected in the low-mass Class 0 protostellar binary,

star-forming regions before planets or life is formed.[citation needed
]

Chloromethane has been detected in space.[14]

Production

Chloromethane was first synthesized by the French chemists

Eugene Peligot in 1835 by boiling a mixture of methanol, sulfuric acid, and sodium chloride. This method is the forerunner for that used today, which uses hydrogen chloride instead of sulfuric acid and sodium chloride.[15]

Chloromethane is produced commercially by treating methanol with hydrochloric acid or hydrogen chloride, according to the chemical equation:[5]

CH3OH + HCl → CH3Cl + H2O

A smaller amount of chloromethane is produced by treating a mixture of methane with chlorine at elevated temperatures. This method, however, also produces more highly chlorinated compounds such as dichloromethane, chloroform, and carbon tetrachloride. For this reason, methane chlorination is usually only practiced when these other products are also desired. This chlorination method also cogenerates hydrogen chloride, which poses a disposal problem.[5]

CH4 + Cl2 → CH3Cl + HCl
CH3Cl + Cl2 → CH2Cl2 + HCl
CH2Cl2 + Cl2 → CHCl3 + HCl
CHCl3 + Cl2 → CCl4 + HCl

Dispersion in the environment

CH3Cl measured by the Advanced Global Atmospheric Gases Experiment (AGAGE) in the lower atmosphere (troposphere) at stations around the world. Abundances are given as pollution free monthly mean mole fractions in parts-per-trillion.

Most of the methyl chloride present in the environment ends up being released to the atmosphere. After being released into the air, the atmospheric lifetime of this substance is about 10 months with multiple natural sinks, such as ocean, transport to the stratosphere, soil, etc.[16][17][18]

On the other hand, when the methyl chloride emitted is released to water, it will be rapidly lost by

volatilization. The half-life of this substance in terms of volatilization in the river, lagoon and lake is 2.1 h, 25 h and 18 days, respectively.[19][20]

The amount of methyl chloride in the stratosphere is estimated to be 2 x 106 tonnes per year, representing 20-25% of the total amount of chlorine that is emitted to the stratosphere annually.[21][22]

Uses

Large scale use of chloromethane is for the production of

organosilicon compounds.[5] These compounds arise via the direct process
. The relevant reactions are (Me = CH3):

x MeCl + Si → Me3SiCl, Me2SiCl2, MeSiCl3, Me4Si2Cl2, ...

Dimethyldichlorosilane (Me2SiCl2) is of particular value as a precursor to silicones, but trimethylsilyl chloride (Me3SiCl) and methyltrichlorosilane (MeSiCl3) are also valuable. Smaller quantities are used as a solvent in the manufacture of

petroleum refining
.

Chloromethane is employed as a

catalyst carrier in low-temperature polymerization, as a fluid for thermometric and thermostatic equipment, and as a herbicide
.

Obsolete applications

Chloromethane was a widely used refrigerant, but its use has been discontinued. It was particularly dangerous among the common refrigerants of the 1930s due to its combination of toxicity, flammability and lack of odor as compared with other toxic refrigerants such as sulfur dioxide and ammonia.[23] Chloromethane was also once used for producing lead-based gasoline additives (tetramethyllead).

Safety

Inhalation of chloromethane gas produces

MAC is the same. Prolonged exposure may have mutagenic effects.[5]

See also

References

  1. ^ a b c d e f g h i j k Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  2. ISBN 978-0-85404-182-4
    .
  3. ^ a b c d e NIOSH Pocket Guide to Chemical Hazards. "#0403". National Institute for Occupational Safety and Health (NIOSH).
  4. ^ a b "Methyl chloride". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  5. ^
    ISBN 978-3527306732
    .
  6. ISBN 3-031-26629-3
    .
  7. doi:10.1016/0304-4203(96)00036-9
    .
  8. doi:10.1016/S0304-4203(97)00092-3
    .
  9. S2CID 570389
    .
  10. ^
    PMID 9789006
    .
  11. PMID 10097085
    .
  12. doi:10.1029/1998JD100077
    .
  13. ^ "ALMA and Rosetta Detect Freon-40 in Space".
  14. ^ "ALMA and Rosetta Detect Freon-40 in Space - Dashing Hopes that Molecule May be Marker of Life". eso.org. Retrieved 3 October 2017.
  15. ^ "Chloromethane". American Chemical Society. Retrieved 2022-05-13.
  16. doi:10.1016/1352-2310(95)00387-8
    .
  17. S2CID 221745138
    .
  18. ^ Carpenter LJ, Reimann S, Burkholder JB, Clerbaux C, Hall BD, Hossaini R, Laube JC, Yvon-Lewis SA (2014). "Update on ODSs and Other Gases of Interest to the Montreal Protocol". WMO (World Meteorological Organization), Scientific Assessment of Ozone Depletion: 2014, Global Ozone Research and Monitoring Project.
  19. ISBN 9780070391758
    .
  20. ^ Agency for Toxic Substances and Disease Registry (1990). Toxicological profile for chloromethane.
  21. ^ Borchers R, Gunawardena R, Rasmussen RA (1994). "Long term trend of selected halogenated hydrocarbons". Ozone in the Troposphere and Stratosphere. NASA: 259–262. 19950004240.
  22. doi:10.1029/JC088iC11p06641
    .
  23. ^ https://archive.org/details/sim_consumer-reports_1936-07_1_3/page/5/mode/1up Consumers Union Reports, Vol. 1, No. 3, July 1936, p. 5.

External links

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