Chemical reactivity
Chemical reactivity is analogous to benzo[b]furan, especially electrophilic substitution reactions such as nitration,
halogenation, sulfonation, acylation, and alkylation reactions. The preferred positions are 2 and 2,8, while nitration
takes place at the 3- and 3,8-positions depending on the electrophilicity of the functionality.
Description
Dioxins and furans, two well-known environmental pollutants,
are extremely toxic to humans and many other species. Dibenzofurans
are released into the air from combustion sources,
and are listed as pollutants of concern due to its persistence
in the environment, potential to bioaccumulate, and toxicity
to humans and the environment. These compounds, when
adsorbed on soils or other substrates, are highly persistent
under normal environmental conditions. The Office of Environmental
Health Hazard Assessment reviews risk assessments
submitted under the Air Toxics ‘Hot Spots’ Program (AB 2588)
in which chlorinated dibenzo-p-dioxins and dibenzofurans are
listed. Chlorinated dibenzofurans were calculated as total
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents in the
AB 2588 risk assessments. Dibenzofuran is cited in the Clean Air
Act 1990 Amendments – Hazardous Air Pollutants as a volatile
hazardous air pollutant of potential concern. The Superfund
Amendment Reauthorization Act Section 110 placed dibenzofuran
on the revised Agency for Toxic Substances and Disease
Registry priority list of hazardous substances to be the subject
of a toxicological profile. Dibenzofuran is also listed in the
Massachusetts Substance List for Right to Know Law, the New
Jersey Department of Health Hazard Right to Know Program
Hazardous Substance List, the Pennsylvania Department
of Labor and Industry Hazardous Substance List, and the
California’s Air Toxics ‘Hot Spots’ List (Assembly Bill 2588).
Chemical Properties
white to light yellow crystal powde
Chemical Properties
Dibenzofuran is a white crystalline powder.
Physical properties
Colorless crystals having a creosote-like odor. The least detectable odor threshold concentration in
water at 60 °C was 2 μg/L (Alexander et al., 1982).
Uses
Research chemical. Derived from industrial and experimental coal gasification operations
where the maximum concentration detected in coal gas tar streams was 12 mg/m
3 (Cleland, 1981).
Uses
Dibenzofuran is an industrial chemical or by-product, and is
used as an insecticide, in the production of PVC, industrial
bleaching and incineration.
Uses
Applications for GC (Gas Chromatography) and LC (Liquid Chromatography) Analysis. Dibenzofuran as the model substrate in culture procedures.
Definition
ChEBI: A mancude organic heterotricyclic parent that consists of a furan ring flanked by two benzene rings ortho-fused across the 2,3- and 4,5-positions.
General Description
Colorless white crystalline solid.
Air & Water Reactions
Insoluble in water.
Reactivity Profile
Dibenzofuran is sensitive to prolonged exposure to light .
Fire Hazard
Flash point data for Dibenzofuran are not available. Dibenzofuran is probably combustible.
Synthesis
A certain amount of activated carbon powder was weighed and subjected to acid washing, alkaline washing, oxidizing treatment and anchoring treatment with sodium nitrite to obtain a catalyst carrier, which was dried and prepared for use.
Weigh 0.4422g of palladium chloride with 59.5% purity and 1.0239g of sodium nitrite and add them dropwise to 3g of aqueous solution of catalyst carrier after fully dissolving them in a 50mL mixed solution of 1% dilute hydrochloric acid and methanol at the ratio of 1:1 by volume, impregnate them for 8h, and then add 10mL 37% formaldehyde and 1mL 80% hydrazine hydrate to reduce them for 6h under the condition of 50C, and then filter them after cooling, washing, drying and cooling to obtain Pd/C catalyst with 5% loading.
A kettle reactor was loaded with 0.5g of 5% Pd/C catalyst, 1.0g of trioctylmethylammonium chloride, 5.0g of 2,4,8-trichlorodibenzofuran, 30mL of toluene, and 25mL of 15% NaOH aqueous solution, and the reaction was carried out at the rate of 100mL/min under atmospheric pressure and 100 for 6.0h, and dibenzofuran was obtained by conventional isolation.
_x000D The conversion of trichlorodibenzofuran was 94.71% and the yield of dibenzofuran was 91.12%.
Potential Exposure
This material is used as an insecticide
and in organic synthesis to make other chemicals. It is
derived from coal tar creosote.
First aid
Skin Contact: Flood all areas of body thathave contacted the substance with water. Do not wait toremove contaminated clothing; do it under the water stream.Use soap to help assure removal. Isolate contaminatedclothing when removed to prevent contact by others. EyeContact: Remove any contact lenses at once. Flush eyeswell with copious quantities of water or normal saline for atleast 2030 min. Seek medical attention. Inhalation: Leavecontaminated area immediately; breathe fresh air. Properrespiratory protection must be supplied to any rescuers. Ifcoughing, difficult breathing, or any other symptoms develop, seek medical attention at once, even if symptomsdevelop many hours after exposure. Ingestion: If convulsions are not present, give a glass or two of water or milk todilute the substance. Assure that the person’s airway isunobstructed and contact a hospital or poison center immediately for advice on whether or not to induce vomiting.
Source
Based on laboratory analysis of 7 coal tar samples, dibenzofuran concentrations ranged
from 170 to 4,000 ppm (EPRI, 1990).
Schauer et al. (1999) reported dibenzofuran in diesel fuel at a concentration of 29 μg/g and in a
diesel-powered medium-duty truck exhaust at an emission rate of 28.7 μg/km.
Gas-phase tailpipe emission rates from gasoline-powered automobiles with and without
catalytic converters were 5.5 and 42.2 μg/km, respectively (Schauer et al., 2002).
Environmental Fate
Biological. Dibenzofuran was oxidized by salicylate-induced cells of Pseudomonas sp. strain
9816/11 and isopropyl-β-D-thiogalactopyranoside-induced cells of Escherichia coli JM109(DE3)
(pDTG141) to (1R,2S)-cis-1,2-dihydroxy-1,2-dihydrodibenzofuran (60–70% yield) and (3S,4R)-
cis-3,4-dihydroxy-3,4-dihydrodibenzofuran (30–40% yield) (Resnick and Gibson, 1996).
Soil. The estimated half-lives of dibenzofuran in soil under aerobic and anaerobic conditions
were 7 to 28 and 28 to 112 d, respectively (Lee et al., 1984).
Groundwater. Based on aerobic acclimated and unacclimated groundwater die away test data,
the estimated half-life of dibenzofuran in groundwater ranged from 8.54 to 34.9 d (Lee et al.,
1984).
Photolytic. The estimated half-life for the reaction of dibenzofuran with OH radicals in the
atmosphere ranged from 1.9 to 19 h (Atkinson, 1987).
Chemical/Physical. It was suggested that the chlorination of dibenzofuran in tap water
accounted for the presence of chlorodibenzofuran (Shiraishi et al., 1985).
Dibenzofuran will not hydrolyze because it has no hydrolyzable functional group (Kollig,
1995).
storage
Color Code—Blue: Health Hazard/Poison: Storein a secure poison location.
Shipping
UN3077 Environmentally hazardous substances,
solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous
hazardous material, Technical Name Required.
Purification Methods
Dissolve dibenzofuran in diethyl ether, then shake it with two portions of aqueous NaOH (2M), wash it with water, separate and dry (MgSO4) it. After evaporating the ether, dibenzofuran is crystallised from aqueous 80% EtOH and then dried under vacuum. [Cass et al. J Chem Soc 1406 1958.] High purity material is obtained by zone refining. [Beilstein 17 V 234.]
Toxicity evaluation
Dibenzofuran is a white crystalline solid. It is not soluble in
water, but soluble in organic solvents like alcohol, acetone,
ether, benzene, and acetic acid. Its boiling point is 287°C,
melting point is 86°C, and specific gravity is 1.0886. Its octanol/
water partition coefficient is 4.12.
Presence of dibenzofuran in coal tar, oil and its uses may
result in its release to the environment through various waste
streams. It has very low to no mobility in soil and degrades in
soil. It dissolves in water as well as volatilizes. As a gas phase in
the atmosphere, it reacts with photochemically produced
hydroxy radicals. It is biodegraded rapidly at contaminated
sites by the microorganisms present; otherwise its biodegradation
is relatively slow. It adsorbs very strongly to sediment
and particulate matter in the water column. It has a potential to
bioconcentrate in aquatic organisms.
Incompatibilities
This material is used as an insecticide
and in organic synthesis to make other chemicals. It is
derived from coal tar creosote.
Toxics Screening Level
The initial threshold screening level (ITSL) for dibenzofuran (CAS # 132-64-9) is 4 μg/m3 with a 24-hour averaging time.
Waste Disposal
In accordance with
40CFR165, follow recommendations for the disposal of
pesticides and pesticide containers. Must be disposed prop-
erly by following package label directions or by contacting
your local or federal environmental control agency, or by
contacting your regional EPA office.
