| Chemical Abstract Number (CAS #) |
74953
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| Synonyms | Dibromomethane |
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Methylene bromide | Methane, dibromo |
| Analytical Methods |
EPA Method 502.2 |
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EPA Method 524.1 |
EPA Method 524.2 |
EPA Method 8010B |
EPA Method 8021A |
EPA Method 8240B |
EPA Method 8260A |
| Molecular Formula | CH2Br2 |
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| Use | IN ORGANIC SYNTHESIS
SOLVENT FOR FATS, WAXES, & RESINS; HEAVY LIQUID IN SOLID SEPARATIONS;
INGREDIENT OF FIRE EXTINGUISHING FLUIDS; GAGE FLUID
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| Apparent Color | CLEAR, COLORLESS LIQUID
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| Boiling Point | 96.95 DEG C
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| Melting Point | -52.5 DEG C
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| Molecular Weight | 173.83
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| Density | 2.4970 @ 20 DEG C/4 DEG C
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| Environmental Impact | Dibromomethane finds limited use in chemical synthesis, as a solvent, and as a gage fluid.
It may be released to the environment during these uses as well as in its production and transport.
Natural production by marine algae also adds to its environmental input. If released on soil,
dibromomethane should volatilize from the soil surface and leach into the ground. If released in
water, dibromomethane would be primarily lost by volatilization (half life 5.2 hr from a model
river). Adsorption to sediment and bioconcentration in aquatic organisms should not be
significant. No significant biotic or abiotic degradative processes have been reported in natural
waters or soil. However, catalyzed photolysis may occur in surface layers of some natural waters
or soil. In the atmosphere, dibromomethane will be lost by reaction with photochemically
produced hydroxyl radicals. The estimated half life for this reaction is 213 days. Dibromomethane
should also be readily scavenged by rain and snow. However, this dibromomethane will be
returned to the atmosphere by volatilization. The general population will be exposed to low levels
of dibromomethane in the atmosphere from both natural and anthropogenic sources. Limited
occupational exposure via inhalation and dermal contact will also occur.
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| Environmental Fate | Polyhalomethanes, including dibromomethane and tribromomethane, have been detected
in surface water of the North and South Atlantic, in air samples collected in the lower marine and
continental troposphere and in rain as well, collected in southern Germany.
TERRESTRIAL FATE: Dibromomethane has a high vapor pressure and low adsorptivity to soil.
Consequently, if released on soil, it will be expected to volatilize from the soil surface and leach
into the ground. Catalyzed photolysis may take place on the soil surface. Its fate in soil and
groundwater is unknown.
AQUATIC FATE: If released in water, dibromomethane would be primarily lost by volatilization
(half life 5.2 hr from a model river(1,SRC)). Catalyzed photolysis may occur in surface layers of
some natural waters.
ATMOSPHERIC FATE: In the atmosphere, dibromomethane will be lost by reaction with
photochemically produced hydroxyl radicals. The estimated half life for this reaction is 213
days . Dibromomethane is very soluble in water (11,700 g/l at 15 deg C ) and therefore it
should be readily scavenged by rain and snow.
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| Drinking Water Impact | DRINKING WATER: In a survey of 14 treated drinking water supplies of varied sources
in England, dibromomethane was detected in seven supplies . These supplies were derived from
groundwater and surface water sources. Dibromomethane was detected in treated drinking water
from the Niagara River in the range 0.2-0.8 ppb .
GROUNDWATER: No detectible dibromomethane was found in samples from a study of
groundwater contamination at 19 municipal and 6 industrial landfill sites in Wisconsin . Of the
377 and 282 representative samples of groundwater and surface water in New Jersey that were
analyzed for dibromomethane, 12% and 28%, respectively, contained dibromomethane . Ninety
precent of the samples of both types contained equal or less than 0.1 ppb of dibromomethane .
The maximum dibromomethane concentration in groundwater was 44.9 and that in surface water
was 358.6 ppb Dibromomethane was found at 9 of 17 stations in the Lower Niagara River;
levels up to 5 parts per trillion were found .
SURFACE WATER: Dibromomethane is a major volatile organic hydrocarbon in Narraganset
Bay . However levels and distribution of the chemical were not reported. Surface seawater
concentrations of dibromomethane at a site in the South Atlantic, and two sites in the North
Atlantic (south of the Canary Islands and west of the Strait of Gibraltar) were 0.26, >1, and 0.3
ng/l . In Lake Ontario, dibromomethane was detected in 66% of the 82 stations that were
sampled . Only 8 samples contained more than trace amounts of dibromomethane and the
highest level was 7 parts per trillion. The detection limit was 0.7 parts per trillion.
RAIN/SNOW: The concentration of dibromomethane in rain collected in Ulm, southern Germany
was 1.4 ng/l . This rain was in a fast moving front coming from the North Atlantic.
EFFL: In a comprehensive survey of wastewater from 4000 industrial and publicly owned
treatment works (POTWs) sponsored by the Effluent Guidelines Division of the U.S. EPA,
dibromomethane was identified in discharges of the following industrial categories (positive
occurrences, median concn in ppb): nonferrous metals (8; 2.2), organics and plastics (2; 32.9),
inorganic chemicals (2; 1.9), pesticides manufacture (2; 104.6), publicly owned treatment works
(9; 0.3) . Maximum effluent concn >100 ppb were found in the nonferrous metals industry (286
ppb) and in pesticide manufacturing (151 ppb) . In a previous survey of 63 wastewaters from a
wide range of chemical manufacturers across the U.S., 1 effluent contained dibromomethane .
The level of dibromomethane in that sample was >100 ppb.
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