Этилбензол

Химические свойства

Ethylbenzene is a colorless liquid. Pungent aromatic odor. The Odor Threshold is 0.092
0.60 ppm

Физические свойства

Clear, colorless liquid with a sweet, gasoline-like odor. At 40 °C, the average odor threshold concentration and the lowest concentration at which an odor was detected were 550 and 150 μg/L, respectively. Similarly, at 25 °C, the average taste threshold concentration and the lowest concentration at which a taste was detected were 780 and 390 μg/L, respectively (Young et al., 1996). The average least detectable odor threshold concentrations in water at 60 °C and in air at 40 °C were 2.4 and 72 μg/L, respectively (Alexander et al., 1982). Cometto-Mu?iz and Cain (1994) reported an average nasal pungency threshold concentration of 10,100 ppm_v.

Вхождение

Has apparently not been reported to occur in nature.

Использование

Anesthetic.
Ethylbenzene is almost exclusively (> 99%) used as an intermediate for the production of styrene monomer. Less than 1 % of the ethylbenzene produced is used as a paint solvent or as an intermediate for the production of diethylbenzene and acetophenone (IARC 2000).
Ethylbenzene is a constituent (15-20%) of commercial xylene (“mixed xylenes”), and hence used as a component of solvents, as a diluent in paints and lacquers, and as a solvent in the rubber and chemical manufacturing industries (WHO 1996).
Ethylbenzene has been added to motor and aviation fuels because of its anti-knock properties. Estimates of ethylbenzene in gasoline have ranged from <1-2.7%. (IARC 2000).

Определение

ethylbenzene: A colourless flammableliquid, C₆H₅C₂H₅; r.d. 0.867;m.p. –95°C; b.p. 136°C. It is madefrom ethene and ethybenzene by aFriedel–Crafts reaction and is usedin making phenylethene (for polystyrene).

Методы производства

Ethylbenzene is produced by alkylation of benzene with ethylene, except for a very small fraction that is recovered from mixed C8 aromatics by superfractionation. The reaction takes place on acidic catalysts and can be carried out either in the liquid or vapor phase.

Подготовка

By Friedel-Crafts reaction on benzene, ethylbromide and aluminium chloride (Arc tander, 1969).
Ethylbenzene is manufactured by alkylation from benzene and ethylene.

Общее описание

A clear colorless liquid. Flash point 59°F. Less dense than water (at 7.2 lb / gal) and insoluble in water. Hence floats on water. Vapors heavier than air. Used as a solvent and to make other chemicals.
Sweet. but somewhat "gassy" odor. If at all reminiscent of any natural material, it would be a Hyacinth-type of gassy sweetness.

Реакции воздуха и воды

Highly flammable. Insoluble in water.

Профиль реактивности

Ethylenzene can react vigorously with strong oxidizing materials .

Опасность

Toxic by ingestion, inhalation, and skin absorption; irritant to skin and eyes. Flammable, dangerous fire risk. Possible carcinogen.

Угроза здоровью

The acute toxicity of Ethylbenzene is low.At high concentrations its exposure producesnarcotic effects similar to benzene andtoluene. A 4-hour exposure to a concentrationof 4000 ppm proved fatal to rats. The lethaldose varies with species. Deaths resulted fromintense congestion and edema of the lungs.
Other than the narcotic effects, Ethylbenzeneexhibits irritant properties that are somewhatgreater than those of benzene or toluene.It is an irritant to the skin, eyes, and nose.Repeated contact with the liquid may causereddening of the skin and blistering. Thevapors at 200 ppm may cause mild irritationof the eyes in humans, which may becomesevere and lacrimating at 2000–3000 ppm.
The oral toxicity in animals was foundto be low to very low. An LD50 value of3500 mg/kg for rats has been documented(NIOSH 1986). No adverse effects werenoted in animals subjected to chronic inhalationexposure at below 400 ppm. At higherdosages only the liver was affected (ACGIH1986). Ethylbenzene is eliminated from thebody by metabolic excretion. The urinarymetabolites in humans are mainly mandelicacid, C6H5CH(OH)COOH, and benzoylformicacid, C6H5COCOOH.

Химическая реактивность

Reactivity with Water No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.

Профиль безопасности

Moderately toxic by ingestion and intraperitoneal routes. Mildly toxic by inhalation and skin contact. An experimental teratogen. Other experimental reproductive effects. Human systemic effects by inhalation: eye, sleep, and pulmonary changes. An eye and skin irritant. Human mutation data reported. The liquid is an irritant to the skin and mucous membranes. A concentration of 0.1% of the vapor in air is an irritant to human eyes, and a concentration of 0.2% is extremely irritating at first, then causes dizziness, irritation of the nose and throat, and a sense of constriction in the chest. Exposure of guinea pigs to 1% concentration has been reported as causing ataxia, loss of consciousness, tremor of the extremities, and finally death through respiratory failure. The pathological findings were congestion of the brain and lungs with edema. A very dangerous fire and explosion hazard when exposed to heat or flame; can react vigorously with oxidizing materials. To fight fire, use foam, CO2, dry chemical. Emitted from modern budding materials (CENEAR 69,22,91). When heated to decomposition it emits acrid smoke and irritating fumes.

Возможный контакт

Ethylbenzene is used in styrene manufacture and in synthesis of p-nitroacetophenone; in the manufacture of cellulose acetate, and synthetic rubber. It is also used as a solvent or diluent; and as a component of automotive and aviation gasoline. Significant quantities of EB are present in mixed xylenes. These are used as dilatants in the paint industry, in agricultural sprays for insecticides and in gasoline blends (which may contain as much as 20% EB). In light of the large quantities of EB produced and the diversity of products in which it is found, there may exist environmental sources for ethylbenzene, e.g., vaporization during solvent use; pyrolysis of gasoline and emitted vapors at filling stations. Groups of individuals who are exposed to EB to the greatest extent and could represent potential pools for the expression of EB toxicity include: (1) individuals in commercial situations where petroleum products or by-products are manufactured e.g., rubber or plastics industry); (2) individuals residing in areas with high atmospheric smog generated by motor vehicle emissions

Метаболизм

The main oxidation of ethyl benzene occurs at the activated α-methylene group to yield methylphenylcarbinol which is also the precursor of hippuric and mandelic acids. Both optical isomers of methylphenylcarbinol are formed, probably in equal amounts, and these have been isolated from the urine of rabbits as the corresponding glucuronides. The two optical forms of mandelic acid have also been found (Williams, 1959).

Перевозки

UN1175 Ethylbenzene, Hazard Class: 3; Labels: 3-Flammable liquid

Несовместимости

Vapors may form explosive mixture with air. 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, and epoxides. Attacks plastics and rubber. May accumulate static electrical charges, and may cause ignition of its vapors.

Утилизация отходов

Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed