| Chemical Abstract Number (CAS #) |
74873
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| Synonyms | Chloromethane |
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Methyl chloride | Methane, chloro |
| Analytical Methods |
EPA Method 502.2 |
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EPA Method 524.1 |
EPA Method 524.2 |
EPA Method 601 |
EPA Method 624 |
EPA Method 8010B |
EPA Method 8021A |
EPA Method 8240B |
EPA Method 8260A |
| Molecular Formula | CH3Cl |
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| Use | MEDICATION: LOCAL ANESTHETIC
As aerosol propellant (former use)
FOAMING AGENT IN PLASTICS INDUSTRY; IN STAINLESS STEEL INDUSTRY
IN MFR OF TETRAMETHYL LEAD, METHYL CELLULOSE, FUMIGANTS, SYNTHETIC
RUBBER; ALSO AS A METHYLATING AGENT, PROPELLANT, AND HERBICIDE
FLUID FOR THERMOMETRIC & THERMOSTATIC EQUIPMENT
EXTRACTANT FOR OILS, FATS AND RESINS
CHEM INT (UNISOLATED) FOR METHYLENE CHLORIDE & CHLOROFORM, CHEM
INT FOR METHYLARSONATE HERBICIDES, QUATERNARY AMMONIUM
CHLORIDES, METHYL MERCAPTAN; SOLVENT & DILUENT IN PRODN OF BUTYL
RUBBER.
Methyl chloride is primarily used to produce silicone resins and rubbers.
Methyl chloride is used to terminate the polymerization of bakelite polysulfone. This controls the
molecular weight of the polymer and contributes to thermal stability
Timber products processing
Blowing agent for some polystyrene foams.
As a refrigerant
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| Consumption Patterns | CHEM INT FOR METHYLCHLOROSILANES, 76%; CHEM INT FOR
TETRAMETHYL LEAD, 9%; SOLVENT & DILUENT IN PRODN OF BUTYL RUBBER,
3%; CHEM INT FOR OTHER CHEMS, EG, METHYL CELLULOSE,
METHYLARSONATES, 12% (1981- EXCLUDES CHEM INT FOR METHYLENE
CHLORIDE & CHLOROFORM)
Silicones, 72%; agricultural chemical, 8%; methyl cellulose, 6%; quaternary amines, 5%; butyl
rubber, 3%; miscellaneous, including tetramethyl lead, 2%; export, 4% (1983)
CHEMICAL PROFILE: Methyl Chloride. Silicones, 74%; agricultural chemicals, 7%; methyl
cellulose, 6%; quaternary amines, 5%; butyl rubber, 2%; miscellaneous, 2%; exports, 4%.
(1987)]
CHEMICAL PROFILE: Methyl chloride. Demand: 1988: 540 million lb; 1989: 550 million lb;
1993 projected/: 580 million lb. (Includes exports, but not imports, which are negligible). (1989)]
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| Apparent Color | COLORLESS GAS; COMPRESSES TO COLORLESS LIQUID
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| Odor | ETHEREAL ODOR (LIQUID) ; Faint, sweet odor
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| Boiling Point | -23.7 DEG C
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| Melting Point | -97 DEG C
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| Molecular Weight | 50.49
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| Density | 0.9159 @ 20 DEG C/4 DEG C
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| Odor Threshold Concentration | Odor recognition in air: 1.00x10 1 ppm (chemically pure)
Odor not noticeable at dangerous concentrations.
Odor Threshold (air) 21 mg/cu m
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| Sensitivity Data | Vapor: Not irritating to eyes, nose or throat. Liquid: Will cause frostbite.
Threshold of irritation: 1050 mg/cu m. From table
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| Environmental Impact | Methyl chloride is produced naturally in the oceans by mechanisms which are not entirely
understood. One source is believed to be the reaction of biologically produced methyl iodide with
chloride ions. Other significant natural sources include forest and brush fires and volcanoes.
Although the atmospheric budget of methyl chloride can be accounted for by volatilization from
the oceanic reservoir, it is apparent that man-made sources arising from its production and use in
the manufacture of silicones and other chemicals and as a solvent and propellant can make a
significant impact on the local atmospheric concn of methyl chloride. If released into water,
methyl chloride will be rapidly lost by volatilization (half-life in a typical river 2.1 hr). It will also
be rapidly lost from soil by volatilization although there is a potential for it to leach into
groundwater where it may very slowly biodegrade and hydrolyze (half-life may exceed a yr). Once
in the atmosphere it will disperse and will be lost primarily by upward dispersion. Above the
tropopause, reaction with hydroxyl radicals aid in the removal of methyl chloride and above 30
km, photodissociation, diffusion and reaction with hydroxyl radicals make roughly equal
contributions to its removal. Humans are exposed to methyl chloride from the ambient air via
inhalation.
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| Environmental Fate | ATMOSPHERIC FATE: The dominant loss mechanism for methyl chloride in the
troposphere is upward diffusion although washout by rain may also be important. From the
tropopause to about 30 km, both upward diffusion and reaction with hydroxyl radicals will be of
approximately equal importance, and above 30 km in the stratosphere diffusion, reaction with
hydroxyl radicals, and photodissociation will have approximately equal weight . The surface
half-life resulting from upward diffusion is 80 days(1,SRC).
AQUATIC FATE: If methyl chloride is released into water, it will be lost primarily by
volatilization (half-life 2.1 hr in a typical river).
TERRESTRIAL FATE: Methyl chloride has a very high vapor pressure and if released on land
will be rapidly lost by volatilization. It may also leach into groundwater where it should very
slowly biodegrade or hydrolyze.
Waste water treatment: evaporation from water at 25 deg C of a 1 ppm solution: 50% after 27
min, 90% after 91 min
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| Drinking Water Impact | DRINKING WATER: Treated water from 30 Canadian potable water treatment facilities
- 2 samples pos, mean (5 ppb) . Drinking water well in Maine reported in a Council on
Environmental Quality survey of contaminated drinking water from groundwater sources 44
ppb . Highest reported concn of methyl chloride in surface water derived drinking water 12
ppb . Identified, not quanitified in drinking water in New Orleans, Cincinnati, Miami,
Philadelphia, and Ottumwa, IA of the 10 cities surveyed . Not detected (DL 0.1 ppb) in treated
water at 10 water treatment plants (42 samples) using Great Lakes water .
GROUNDWATER: Detected, not quantified in 11 of 20 groundwaters underlying municipal solid
waste landfills in MN .
SURFACE WATER: 895 stations in the USEPA STORET data base 1.4% pos, median < 10
ppb . Raw water from 30 Canadian potable water treatment facilities - 1 sample pos, mean < 5
ppb . Detected in the Niagara River and the open water of Lake Ontario . Not detected (DL
0.1 ppb) in raw water at 10 water treatment plants (42 samples) using Great Lakes water .
SEAWATER: Pacific Ocean 26.8 parts per trillion at surface, 3.3 parts per trillion at 300 m
depth . Eastern Pacific surface water (latitude 29 deg N to -29 deg S) 6.3-42 parts per trillion,
11.5 parts per trillion mean, 200-300% supersaturation . Point Reyes, CA (nearshore) 1200
parts per trillion .
EFFL: 1298 stations in the USEPA STORET data base 3.5% pos, median < 10 ppb . Detected
in 1 of 5 leachates from municipal waste landfills in WI 170 ppb and detected, not quantified in 4
of 6 leachates from municipal landfills in MN . Methyl chloride has been detected in treated
wastewater from the following industries (industry (mean concn)): pharmaceutical manufacturing
(2000 ppb), organic chemical manufacturing/plastics (0.1 ppb), timber products processing (140
ppb) and raw wastewater from metal finishing (610 ppb) . Ratios of methyl chloride (ppmv) to
carbon dioxide (1X10-6 ppmv) in wood smoke ranged from 0.66 to 2.63 . In a comprehensive
survey of wastewater from 4000 industrial and publicly owned treatment works (POTWs)
sponsored by the Effluent Guidelines Div of the U.S. EPA, methyl chloride was identified in
discharges of the following industrial categories (frequency of occurrence, median concn in ppb):
nonferrous metals (1; 21.6), paint and ink (2; 4128.7), printing and publishing (1; 6.0), organics
and plastics (1; 156.7), pharmaceuticals (1; 2558.3), organic chemicals (3; 49.0) . The highest
effluent conc was 4194 ppb in the paint and ink industry .
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