| Chemical Abstract Number (CAS #) |
95476
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| Synonyms | o-Xylene |
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1,2-Dimethylbenzene |
| Analytical Methods |
EPA Method 502.2 |
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EPA Method 503.1 |
EPA Method 524.1 |
EPA Method 524.2 |
EPA Method 602 |
EPA Method 624 |
EPA Method 8020A |
EPA Method 8021A |
EPA Method 8260A |
| Molecular Formula | C8H10 |
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| Use | Raw material for production of plasticizers; alkyd resins, glass-enforced polyesters,
manufacture of phthalic anhydride
Vitamin and pharmaceutical syntheses; dyes; insecticides; motor fuels.
CHEM INTERMEDIATE FOR PHTHALONITRILE
CHEM INTERMEDIATE FOR OTHER DERIVATIVES
Reacts with hexafluoroacetone to produce 4,4'-(Trifluoro-1-(trifluoromethyl)ethylidene)
diphthalic anhydride, an intermediate in the preparation of high-performance polyimide polymers
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| Consumption Patterns | CHEM INTERMEDIATE FOR PHTHALIC ANHYDRIDE, 95.1%; OTHER, 4.9%
(1979 NON-GASOLINE USE)
Phthalic anhydride, 50%; exports, 50% (1982) estimate
CHEMICAL PROFILE: Orthoxylene. Phthalic anhydride, 87%; exports, 13%.
CHEMICAL PROFILE: Orthoxylene. Demand: 1988: 945 million lb; 1989: 860 million lb; 1993
/projected/: 1,070 million lb. (Includes exports, but not imports, which totaled about 90 million
lb).
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| Apparent Color | Colorless liquid
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| Odor | Sweet
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| Boiling Point | 144.4 deg C @ 760 mm Hg
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| Melting Point | -25 DEG C
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| Molecular Weight | 106.16
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| Density | 0.8801 @ 20 deg C/4 deg C
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| Odor Threshold Concentration | 0.05 PPM
1.8 ppm in water
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| Sensitivity Data | Xylene vapor may cause irritation of the eyes, nose, and throat. At high concentrations,
xylene vapor may cause severe breathing difficulties which may be delayed in onset. Repeated or
prolonged exposure may cause a skin rash. Xylenes
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| Environmental Impact | o-Xylene will enter the atmosphere primarily from fugitive emissions and exhaust
connected with its use in gasoline. Industrial sources include emissions from petroleum refining,
coal tar and coal gas distillation and from its use as a solvent. Discharges and spills on land and in
waterways result from its use in diesel fuel and gasoline. Most of the o-xylene is released into the
atmosphere where it may photochemically degrade by reaction with hydroxyl radicals (half-life
1.5-15 hr). The dominant removal process in water is volatilization. o-Xylene is moderately
mobile in soil and may leach into groundwater where it has been known to be detectable for
several years, although there is some evidence that it biodegrades in both soil and groundwater.
Bioconcentration is not expected to be significant. The primary source of exposure is from the air,
especially in areas with high traffic.
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| Environmental Fate | TERRESTRIAL FATE: When spilled on land, o-xylene will volatilize and leach into the
ground. o-Xylene may be degraded during its passage through the soil . The extent of the
degradation will undoubtably depend on its concentration, residence time in the soil, the nature of
the soil and whether resident microbial populations have been acclimated.
AQUATIC FATE: In surface waters, volatilization appears to be the dominant removal process
(half-life 1-5 days(1,SRC)). Some adsorption to sediment will occur. Although o-xylene is
biodegradable and has been observed to degrade in seawater, there is insufficient data to access
the rate of this process in natural aquatic systems. Although it has been observed to degrade in
groundwater, it is known to persist for many years in groundwater, at least at sites where the
concentration might have been quite high.
ATMOSPHERIC FATE: When released into the air, o-xylene may degrade by reaction with
photochemically produced hydroxyl radicals (half-life 1.5 hr - summer, 15 hr - winter ).
However, ambient levels are detected because of large emissions .
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| Drinking Water Impact | DRINKING WATER: In treated water from 30 Canadian water treatment facilities in
which o- or m-xylene combined were measured, 27% and 20% were positive in summer and
winter respectively, with max values of 7 and 2 ppb respectively, and mean values below 1
ppb . In 12 Great Lake municipalities tested on one or two days, 5 communities were free of m-
and o-xylene combined with median community levels being 1.0 ppb and the highest sample of
combined isomers being 12 ppb . o-Xylene was detected but not quantified in drinking water
from Philadelphia, PA , Washington, DC , Tuscaloosa, AL , and Houston, TX . In 3
New Orleans treatment plants, the avg concn of water collected over 2 days was 3.4 ppb(6). Bank
filtered drinking water in the Netherlands contained a max of 30 parts per trillion o-xylene(7). In 5
drinking water wells near and down gradient from a landfill - 0.2-1.5 ppb, control well upstream -
0.8 ppb(8). In a survey of organics in drinking water derived from groundwater sources, o- and
p-xylene combined were found in 2.1% of 280 sample sites supplying <10,000 persons and 1.1%
of 186 sites suppyling >10,000 persons. The maximum combined concn were 0.59 and 0.91 ppb,
respectively(9). Detected in all 14 drinking water supplies studies, 10 from surface sources and 4
from ground sources in the lowland of Great Britain(10).
GROUNDWATER: In the Chalk Aquifer in England, 1550 ppb o-xylene was measured 10 m
from the tank and 0.02 ppb was found in a public water supply 210 m from the tank . At the
How Creek coal gasification site in Wyoming, 260-590 ppb was found 15 months after
gasification was completed . 6 ppb was found in landfill groundwater . Detected in recovery
well from landfill 7 years after closure .
SURFACE WATER: In the raw water for 30 Canadian water treatment facilities, 7% and 17% of
plants contained combined o- and m-xylene in summer and winter, respectively with max levels
being under 1 ppb . Detected, not quantified, in the Mississippi R , the Black Warrior R in
Tuscaloosa, AL , and the Glatt R in Switzerland .
SEAWATER: In Vineyard Sound, MA samples taken from March through June ranged from 1.8
to 25 parts per trillion and avg 9.4 parts per trillion . In open ocean and coastal sections of the
Gulf of Mexico, 1-30 parts per trillion .
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