PENTACHLOROBENZENE

Chemical properties

Pentachlorobenzene is a colorless crystalline solid. Pleasant aroma.

The Uses of PENTACHLOROBENZENE

It was used to prepare tetrachlorobenzene by photolysis.

The Uses of PENTACHLOROBENZENE

Agrochemical researc

Definition

ChEBI: A member of the class of pentachlorobenzenes that is benzene in which five of the hydrogens are replaced by chlorines. Now classed as a persistent organic pollutant under the Stockholm Convention.

Synthesis Reference(s)

The Journal of Organic Chemistry, 38, p. 2928, 1973 DOI: 10.1021/jo00957a002

General Description

White crystals.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

PENTACHLOROBENZENE is relatively unreactive. May be incompatible with strong oxidizing and reducing agents. Also may be incompatible with many amines, nitrides, azo/diazo compounds, alkali metals, and epoxides.

Fire Hazard

Flash point data for PENTACHLOROBENZENE are not available but PENTACHLOROBENZENE is probably non-flammable.

Safety Profile

Moderately toxic by ingestion. An experimental teratogen. When heated to decomposition it emits toxic fumes of Cl-. See also CHLORINATED HYDROCARBONS, AROMATIC

Potential Exposure

Pentachlorobenzene is used primarily as a precursor in the synthesis of the fungicide pentachloronitrobenzene, and as a flame retardant. Drug/ Therapeutic Agent; Fungicide; bactericide; wood preservative; industrial Insecticides.

Source

Pentachlorobenzene may enter the environment from leaking dielectric fluids containing this compound. Pentachlorobenzene may be present as an undesirable by-product in the chemical manufacture of hexachlorobenzene, pentachloronitrobenzene, tetrachloroenzenes, tetrachloroethylene, trichloroethylene, and 1,2-dichloroethane (U.S. EPA, 1980).

Environmental Fate

Biological. In activated sludge, <0.1% mineralized to carbon dioxide after 5 days (Freitag et al., 1985). From the first-order biotic and abiotic rate constants of pentachlorobenzene in estuarine water and sediment/water systems, the estimated biodegradation half-lives were 4.6–6.5 and 6.0–7.6 days, respectively (Walker et al., 1988)
Photolytic. UV irradiation (λ = 2537 ?) of pentachlorobenzene in a hexane solution for 3 hours produced a 50% yield of 1,2,4,5-tetrachlorobenzene and a 13% yield of 1,2,3,5- tetrachlorobenzene (Crosby and Hamadmad, 1971). Irradiation (λ ≥285 nm)
A carbon dioxide yield of 2.0% was achieved when pentachlorobenzene adsorbed on silica gel was irradiated with light (λ >290 nm) for 17 hours (Freitag et al., 1985).
The experimental first-order decay rate for pentachlorobenzene in an aqueous solution containing a nonionic surfactant micelle (Brij 58, a polyoxyethylene cetyl ether) and illuminated by a photoreactor equipped with 253.7-nm monochromatic UV lamps, is 1.47 × 10–2/sec. The corresponding half-life is 47 seconds. Photoproducts reported include, all
tetra-, tri- and dichlorobenzenes, chlorobenzene, benzene, phenol, hydrogen and chloride ions (Chu and Jafvert, 1994)

Shipping

UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required.

Incompatibilities

Polychlorinated hydrocarbons Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides, aluminum, liquid oxygen; potassium, sodium.

Waste Disposal

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration after mixing with another combustible fuel. Care must be exercised to assure complete combustion to prevent the formation of phosgene. An acid scrubber is necessary to remove the halo acids produced.