| Chemical Abstract Number (CAS #) |
120832
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| Synonyms | 2,4-Dichlorophenol |
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Phenol, 2,4-dichloro- |
| Analytical Methods |
EPA Method 604 |
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EPA Method 625 |
EPA Method 8040A |
EPA Method 8250A |
| Molecular Formula | C6H4Cl2O |
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| Use | IN SYNTHESIS OF ANTIHELMINTHIC BITHIONOL SULFOXIDE
CHEM INT FOR HERBICIDES SUCH AS 2,4-DICHLOROPHENOXYACETATE,
BIFENOX & DICHLORPROP HERBICIDES, 4-(2,4-DICHLOROPHENOXY)BUTYRATE
HERBICIDE
2,4-DCP is used as a feedstock for the manufacture of certain methyl cmpd used in
mothproofing, antiseptics & seed disinfectants. 2,4-DCP is also reacted with benzene sulfonyl
chloride to produce miticide or further chlorinated to pentachlorophenol, a wood preservative.
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| Apparent Color | COLORLESS CRYSTALS ; HEXAGONAL NEEDLES FROM BENZENE ; WHITE
SOLID
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| Odor | Strong medicinal
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| Boiling Point | 210 DEG C
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| Melting Point | 45 DEG C
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| Molecular Weight | 163.00
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| Density | 1.383 AT 60 DEG C/25 DEG C
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| Odor Threshold Concentration | Odor detection in water: 2.10X10-1 ppm (chemically pure)
In air: 0.21 ppm Purity not specified
Detection in water: 0.04 mg/l; 0.002 mg/l; 0.0003 mg/l Purity not specified
In air: low 1.4007 mg/cu m; high 1.4007 mg/cu m Purity not specified
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| Sensitivity Data | Chlorinated benzenes are irritating to the skin, conjunctiva, and mucous membranes of the
upper respiratory tract. Chlorinated benzenes
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| Environmental Impact | 2,4-Dichlorophenol may be released to the environment in effluents from its manufacture
and use as a chemical intermediate and from chlorination processes involving water treatment and
wood pulp bleaching. Releases can also occur from various incineration processes or from
metabolism of various pesticides in soil. If released to the atmosphere, degradation can occur by
reaction with photochemically formed hydroxyl radicals (estimated avg half-life of 5.3 days).
Physical removal from air may occur via rainfall. With a pKa of 7.8, 2,4-dichlorophenol can exist
in both the non-dissociated and ionized forms in environmental soil and water depending upon the
pH of the media. If released to soil, moderate to slow leaching is possible based on observed Koc
values of 200-5000; the ionized form appears more susceptible to leaching than the
non-dissociated form. Various biodegradation studies have demonstrated that 2,4-dichlorophenol
is biodegradable under aerobic and anaerobic conditions in both soil and water. If released to
water, adsorption to sediments may be important under various conditions determined, in part, by
pH. Photodegradation in natural water can occur by direct photolysis or by reaction with
sunlight-formed oxidants (singlet oxygen and peroxy radicals). The general population can be
exposed to 2,4-dichlorophenol through consumption of contaminated tap water or by inhalation
of contaminated air.
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| Environmental Fate | TERRESTRIAL FATE: Contamination of soil in the vicinity of two Finnish sawmills
using preservative (Ky-5) against blue-staining fungi that contained chlorophenols was studied.
The soil around the treatment basins contained up to 70 mg chlorophenols/kg and that in the
storage area for treated lumber up to 6 mg/kg. Contamination extended to a depth of at least 2 m
near the treatment basins. Surface water inside the sawmill area contained the same chlorophenols
as those used in wood preservation, plus some additional isomers. The ground water and lake
water around the sawmill areas were contaminated. The fate of different chlorophenols in soil is
probably affected by many factors, such as the water solubility of each chlorophenol, pH of the
soil, rainfall, soil organic matter content, type and particle size of the soil, biological and
photodegradation and the evaporation of each chlorophenol. Chlorophenols
AQUATIC FATE: The consequences of contamination of the aquatic environment by
chlorophenols including 2,4-dichlorophenol/, have been evaluated by extensive review of the
available scientific data. The chlorophenols generally exert moderate toxic effects to mammalian
and aquatic life, although toxicity to fish upon long-term exposure may be considerable, as has
been found for 2,4-dichlorophenol. Persistence is low when adapted microflora is present, capable
of biodegrading these compounds, but may become moderate to high depending on the
environmental conditions. Bioaccumulation is expected to be low. A striking feature of these
chlorophenols is their strong organoleptic effect. Chlorphenols
Pseudomonas strains capable of mineralizing 2,4-dichlorophenol (DCP) and p-nitrophenol in
culture media were isolated from soil. One DCP-metabolizing strain mineralized 1.0 and 10 ug of
DCP but not 2.0 to 300 ng/ml in culture. When added to lake water containg 10 ug of DCP per
ml, the strain mineralized DCP only after 6 days. The strain did not grow or metabolize DCP
when inoculated into sterile lake water, but did so when the system was amended with glucose.
The bacterium grew in sterile DCP-amended sewage, although not causing appreciable
mineralization of the test compound. A second DCP-utilizing pseudomona failed to mineralize
DCP when added to the surface of sterile soil, although activity was evident if the inoculum was
mixed with the soil.
TERRESTRIAL FATE: The adsorption of 2,4-dichlorophenol by soil material depends, in part,
upon the pH of the soil(1,2,3). With a pKa of 7.8 , 2,4-dichlorophenol can exist in
environmental media in both the non-dissociated and ionized forms. In highly alkaline soils (pH
10), it will be primarily in the ionized form and has been observed to be poorly adsorbed to soil
under such conditions . Non-dissociated 2,4-dichlorophenol is expected to undergo more
adsorption than the ionized form(1,2). Soil Koc values ranging from 200-5000 have been
observed , indicating that either moderate leaching or virtually no leaching are possible
depending on local conditions. Various biodegradation studies have demonstrated that
2,4-dichlorophenol is biodegradable under both aerobic and anaerobic conditions. Biodegradation
may be the most important environmental dissapative process in soil.
AQUATIC FATE: With a pKa of 7.8, 2,4-dichlorophenol can exist in both the non-dissociated
and ionized forms in environmental waters depending upon the pH of the water. Under highly
alkaline conditions (pH 10), the ionized form has been observed to be poorly adsorbed to soil
materials , which suggests that the ionized form may not partition from the water column to
aquatic sediments. Sediment Koc values of 266-3990 have been observed for the non-dissociated
form(2,3), suggesting adsorption may be important. Evidence exists that supports enzymatic
coupling of certain xenobiotic pollutants to humic substances is an important natural process .
In one monitoring study, the concn of 2,4-dichlorophenol was found to be much greater in the
aquatic sediments than in the associated water column .
AQUATIC FATE: Photodegradation in surface water is likely to be important; photolysis
half-lives of 0.7-3.0 hr have been reported for winter-summer conditions at the water surface ;
these half-lives will increase significantly with an increase in water depth. Half-lives of 62 and
69.3 hr can be estimated for reaction with singlet oxygen and peroxy radicals (sunlight formed
oxidants) in natural water under midday sunlight(2,3,SRC). Various biodegradation studies have
shown that 2,4-dichlorophenol is degradable under both aerobic and anaerobic conditions.
Aquatic hydrolysis and volatilization are not expected to be important.
ATMOSPHERIC FATE: Based on a vapor pressure of 0.075 mm Hg at 25 deg C(1,SRC),
2,4-dichlorophenol can be expected to exist almost entirely in the vapor-phase in the ambient
atmosphere(2,SRC). Vapor-phase 2,4-dichlorophenol is degraded in the ambient atmosphere by
reaction with photochemically formed hydroxyl radicals; the half-life for this reaction in typical air
can be estimated to be about 5.3 days(3,SRC). Direct photolysis in air may be possible, but kinetic
rate data specific to air are not available to predict its relative significance. 2,4-Dichlorophenol has
been detected in rainwater from Portland and Beaverton, OR(4,5); therefore, physical removal
from air by means of wet deposition may have some importance.
Atmospheric Fate: The atmospheric half-life of 2,4-dichlorophenol for the oxidation of
vapor-phase by photochemically generated hydroxyl radicals is approximately 7 days. This
value was calculated using estimated reaction rate constants of 1.53x10-12 cu m molecule-sec for
2,4-dichlorophenol at 25 deg C and an ambient hydroxyl radical concn of 8.0x10 5 molecules/cu
m.
Moist soil incubation with 2,4-dichlorophenol showed more decomposition in clay and sandy
loam, than in clay loam. Small amounts of dichloroanisole were formed.
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| Drinking Water Impact | CHLOROPHENOLS IN SEWAGE, STREAM WATER & TAP WATER IN THE
VICINITY OF SEOUL, KOREA FROM JAN TO SEPT, 1979 WAS STUDIED.
CHLORINATED PHENOLS CAN BE PRODUCED BY THE CHLORINATION OF PHENOL
WITH HYPERCHLORITE IN WATER. CHLOROPHENOLS IDENTIFIED FROM TAP
WATER IN SEOUL DURING THE SUMMER OF 1979 WERE: O-CHLOROPHENOL 0.042
PPB; 2,6-DICHLOROPHENOL 0.033 PPB; 2,4-DICHLOROPHENOL 0.003 PPB.
DRINKING WATER: Based on federal studies of finished drinking waters, 2,4-dichlorophenol
has been found in 17.2% of the groundwater supplies . 2,4-Dichlorophenol was detected in 8
raw water samples and 26 treated water samples (out of a total of 480 samples) collected at 40
potable water treatment facilities in Canada between Oct 1984 and July 1985 ; max concn of 17
and 72 ng/l were found in raw and treated water, respectively .
SURFACE WATER: An analysis of the USEPA STORET Database determined that
2,4-dichlorophenol was positively detected in 0.4% of 876 effluent reporting stations at a median
level below 10 ppb . 2,4-Dichlorophenol (plus 2,5-dichlorophenol) levels of 1.8 ug/kg were
detected in water samples taken from the Weser estuary in Germany on Aug 21, 1978 . A
2,4-dichlorophenol level of 0.45 ppb was found in the Rhine River in 1978 . Max levels of 0.59
and 0.35 ppb were detected in the Rhine at Lobith, Netherlands in 1976 and 1977,
respectively .
GROUND WATER: 2,4- Dichlorophenol was detected in 6 of 10 groundwater samples (concn of
3.2-79.7 ppb) taken from two wells (between Oct 1981 and Mar 1983) in the vicinity of an
abandoned creosote facility in Conroe, TX . 2,4-Dichlorophenol was detected in groundwater
associated with an Australian quarry receiving organic waste dumping .
SEAWATER: Seawater from the Gulf of Bothnia (Sweden) was found to contain
2,4-dichlorophenol levels of 2-400 ng/l from samples collected on Sept 13, 1982 and Nov 3,
1983 ; the presence of chlorophenols in the seawater was attributed to effluent discharges from
a sulfate pulp mill .
RAIN/SNOW: An average 2,4-dichlorophenol concn of 1.3 ng/l (range of 0.56-2.5 ng/l) was
detected in rainwater of Portland, OR during monitoring between Feb and Apr 1984 . Levels of
0.55-20 ng/l were detected in rainwater collected in suburban Beaverton, OR in Feb and Apr
1982 .
EFFL: 2,4-DICHLOROPHENOL IS A MAJOR COMPONENT OF PULP MILL EFFLUENTS
FORMED DURING THE MULTI-STEP BLEACHING OF CELLULOSE TO REMOVE
COLORED LIGNIN CONSTITUENTS.
An analysis of the USEPA STORET Database determined that 2,4-dichlorophenol was positively
detected in 3.0% of 1319 effluent reporting stations at a median level below 10 ppb .
2,4-Dichlorophenol levels of 2-11 ng/l were detected in waste liquors from Finnish pulp mills in
1983 ; levels of 234 and 570 ng/g were found in combustion ash from two municipal refuge
incinerators . A 2,4-dichlorophenol concn of 0.1 ng/g was detected in particle effluents from
coal-fired power plants . Combustion effluents from the combustion of municipal solid waste,
wood wastes, and peat have been found to contain 2,4-dichlorophenol .
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