Chemical Properties
Acrylonitrile is a colorless, flammable liquid. Its vapors may explode when exposed to an
open flame. Acrylonitrile does not occur naturally. It is produced in very large amounts
by several chemical industries in the United States and its requirement and demand has
increased in recent years. The largest users of acrylonitrile are chemical industries that make
acrylic and modacrylic fi bers, high impact acrylonitrile-butadiene-styrene (ABS) plastics.
Acrylonitrile is also used in business machines, luggage, and construction material, in the
manufacturing of styrene-acrylonitrile (SAN) plastics for automotive and household goods,
and in packaging material. Adiponitrile is used to make nylon, dyes, drugs, and pesticides.
Definition
ChEBI: A nitrile that is hydrogen cyanide in which the hydrogen has been replaced by an ethenyl group.
Reactivity Profile
ACRYLONITRILE produces poisonous hydrogen cyanide gas on contact with strong acids or when heated to decomposition. Reacts violently with strong oxidizing agents (dibenzoyl peroxide, di-tert-butylperoxide, bromine) [Sax, 9th ed., p. 61]. Rapidly ignites in air and forms explosive mixtures with air. Polymerizes violently in the presence of strong bases or acids. Underwent a runaway reaction culminating in an explosion on contact with a small amount of bromine or solid silver nitrate [Bretherick, 5th ed., 1995, p. 404].
Air & Water Reactions
Highly flammable. Soluble in water.
Health Hazard
ACRYLONITRILE, INHIBITED is classified as very toxic. Probable oral lethal dose for human is 50-500 mg/kg (between 1 teaspoon and 1 oz.) for a 70 kg (150 lb.) person. Irritant skin dose--500 mg. Toxic concentrations have been reported at 16 ppm/20 min. Acute toxicity is similar to that due to cyanide poisoning, and the level of cyanide ion in blood is related to the level of poisoning. Inhalation or ingestion results in collapse and death due to tissue anoxia (lack of oxygen) and cardiac arrest (heart failure).
Potential Exposure
Acrylonitrile is used in the manufacture of synthetic fibers, polymers, acrylostyrene plastics, acrylonitrile butadiene styrene plastics, nitrile rubbers, chemicals, and adhesives. It is also used as a pesticide. In the past, this chemical was used as a room fumigant and pediculicide (an agent used to destroy lice).
Fire Hazard
Materials are too dangerous to health to expose fire fighters. A few whiffs of vapor could cause death or vapor or liquid could be fatal on penetrating the fire fighter's normal full protective clothing. The normal full protective clothing and breathing apparatus available to the average fire department will not provide adequate protection against inhalation or skin contact with these materials. Explosion hazard is moderate. ACRYLONITRILE, INHIBITED is flammable and explosive at normal room temperatures. Can react violently with strong acids, amines, strong alkalis. Vapors may travel considerable distance to source of ignition and flash back. Dilute solutions are also hazardous (flash point of a solution of 2 percent in water is 70F). When heated or burned, toxic hydrogen cyanide gas and oxides of nitrogen are formed. Avoid strong acids, amines, alkalis. Incompatible with strong oxidizers (especially bromine) copper and copper alloys. Unstable, moderate hazard is possible when ACRYLONITRILE, INHIBITED is exposed to flames, strong acids, amines and alkalis. May polymerize spontaneously in the container, particularly in absence of oxygen or on exposure to visible light. If polymerization occurs in containers, there is a possibility of violent rupture.
First aid
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. Medical observation is recommended for 24 to 48 hours after breathing overexposure, as pulmonary edema may be delayed. Use amyl nitrate capsules if symptoms develop. All area employees should be trained regularly in emergency measures for cyanide poisoning and in CPR. A cyanide antidote kit should be kept in the immediate work area and must be rapidly available. Kit ingredients should be replaced every 1 2 years to ensure freshness. Persons trained in the use of this kit; oxygen use, and CPR must be quickly available.
Shipping
UN1093 Acrylonitrile, stabilized, Hazard Class 3; Labels: 3 Flammable liquids, 6.1-Poisonous materials
Incompatibilities
May form explosive mixture with air. Reacts violently with strong acids; strong alkalis; bromine, and tetrahydrocarbazole. Copper, copper alloys, ammonia, and amines may cause breakdown to poisonous products. Unless inhibited (usually with methylhydroquinone), acrylonitrile may polymerize spontaneously. It may also polymerize on contact with oxygen, heat, strong light, peroxides, and concentrated or heated alkalis. Reacts with oxidizers, acids, bromine, amines. Attacks copper and copper alloys. Attacks aluminum in high concentrations. Heat and flame may cause release of poisonous cyanide gas and nitrogen oxides
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 with provision for nitrogen oxides removal from effluent gases by scrubbers or afterburners. A chemical disposal method has also been suggested involving treatment with alcoholic NaOH; the alcohol is evaporatedand calcium hypochlorite added; after 24 hours the product is flushed to the sewer with large volumes of water. Recovery of acrylonitrile from acrylonitrile process effluents is an alternative to disposal.
Physical properties
Clear, colorless to pale yellow-brown, watery, volatile liquid with a sweet, irritating or pungent
odor resembling peach pits, onions, or garlic. Evaporates quickly when spilled. Turns dark on
exposure to air. Odor threshold concentrations of 1.6 and 8.8 ppmv were reported by Stalker
(1973) and Nagata and Takeuchi (1990), respectively.
Production Methods
Acrylonitrile can be prepared by several methods (HSDB 1988). Ethylene oxide is
reacted with hydrogen cyanide to form ethylene cyanohydrin (?-hydroxypropionitrile),
which is then dehydrated in the presence of a catalyst to form acrylonitrile.
A somewhat similar synthesis involves the treatment of ethylene chlorohydrin
with sodium cyanide to form ethylene cyanohydrin. Another method involves the
partial oxidation of natural gas to acetylene which is then reacted with hydrogen
cyanide to form acrylonitrile. Acrylonitrile also can be synthesized from propylene,
oxygen and ammonia with either bismuth phosphomolybdate or a uranium-
based compound as a catalyst (Hawley 1987).
Acrylonitrile is the most extensively produced aliphatic nitrile, ranking 39th on
the list of high-volume chemicals produced in the USA in 1987. In 1985, U.S.
production of acrylonitrile was 1.17 million tons (HSDB 1989).
Technical grade acrylonitrile is greater than 99% pure with the major impurities
being water (present to a maximum of 0.5%), acetone, acetonitrile, acetaldehyde,
iron, peroxides, and hydrogen cyanide (USEPA 1983). Polymerization grade
acrylonitrile can contain the following impurities or additives: dimethylformamide,
hydrogen peroxide, hydroxyanisole, methyl aery late, phenyl ether-biphenyl
mixture, sodium metabisulfite, sulfur dioxide, sulfuric acid and titanium
dioxide (USEPA 1980).
Production Methods
Acrylonitrile is produced in commercial quantities almost exclusively by the vapor-phase catalytic propylene ammoxidation process developed by Sohio.
C3H6 + NH3 + 2/3O2???→ C3H3N +3 H2O
Acrylonitrile must be stored in tightly closed containers in cool, dry, well-ventilated areas away from heat, sources of ignition, and incompatible chemicals. Storage vessels, such as steel drums, must be protected against physical damage, with outside detached storage preferred. Storage tanks and equipment used for transferring acrylonitrile should be electrically grounded to reduce the possibility of static spark-initiated fire or explosion. Acrylonitrile is regulated in the workplace by OSHA (29 CFR 1910).
Flammability and Explosibility
Highly flammable liquid (NFPA rating = 3). Vapor forms explosive mixtures with
air at concentrations of 3 to 17% (by volume). Hazardous gases produced in fire
include hydrogen cyanide, carbon monoxide, and oxides of nitrogen. Carbon dioxide
or dry chemical extinguishers should be used to fight acrylonitrile fires.
Chemical Reactivity
Reactivity with Water No reaction; Reactivity with Common Materials: Attacks copper and copper alloys; these metals should not be used. Penetrates leather, so contaminated leather shoes and gloves should be destroyed. Attacks aluminum in high concentrations; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: May occur spontaneously in absence of oxygen or on exposure to visible light or excessive heat, violently in the presence of alkali. Pure ACN is subject to polymerization with rapid pressure development. The commercial product is inhibited and not subject to this reaction; Inhibitor of Polymerization: Methylhydroquinone (35-45 ppm).
Industrial uses
Acrylonitrile is used in the manufacture of acrylic fibers; in plastics, surface
coatings, and adhesives industries; as a chemical intermediate in the synthesis of
anti-oxidants, pharmaceuticals, dyes, surface-active agents, etc.; and in organic
synthesis to introduce a cyanoethyl group. It is used as a modifier for natural
polymers, and as a pesticide fumigant for stored grain (Hawley 1987; Windholz et
al 1983; HSDB 1989).
Other uses for acrylonitrile includes the cyanoethylation of natural fibers such
as cotton, cellulose, and polysaccharides and the production of acrylonitrilecontaining
plastics, particularly styrene-acrylonitrile (SAN) and acrylonitrilebutadiene
styrene (ABS) co-polymers. Acrylonitrile is also used in the manufacture
of various resins, elastomers, and latexes and has a limited use as a fumigant.
The major source of human exposure to acrylonitrile monomer and its release
into the environment is during its manufacture, polymerization, or molding to
acrylonitrile-based polymers. Disposal of acrylonitrile polymers by burning results
in release of additional acrylonitrile monomer. Residual amounts of acrylonitrile
monomer also are released from fabrics, such as underwear made of
polyacrylonitrile fibers, and acrylonitrile polymer plastics in furniture. The public
may also be exposed to acrylonitrile by ingestion of food products containing
leached residual acrylonitrile monomer from packaging materials, such as 'Saran
Wrap' (Anon. 1977a,b). Cigarette smoke has been shown by gas Chromatographie
analysis to contain aliphatic nitriles including acrylonitrile, propionitrile, and
methacrylonitrile (Izard and Testa 1968).
Biochem/physiol Actions
An industrial carcinogen that is a multisite carcinogen in rats and possibly carcinogenic to humans.
Mechanism of action
Respiratory action.
Carcinogenicity
Acrylonitrile is reasonably anticipated to be a human carcinogenbased on sufficient evidence of carcinogenicity from studies in experimental animals.
Environmental Fate
Biological. Degradation by the microorganism Nocardia rhodochrous yielded ammonium ion and propionic acid, the latter being oxidized to carbon dioxide and water
(DiGeronimo and Antoine, 1976). When 5 and 10 mg/L of acrylonitrile were statically
incubated in the dark at 25°C with yeast extract and settled domestic wastewater inoculum,
complete degradation was observed after 7 days (Tabak et al., 1981)
Photolytic. In an aqueous solution at 50°C, UV light photooxidized acrylonitrile to
carbon dioxide. After 24 hours, the concentration of acrylonitrile was reduced 24.2%
(Knoevenagel and Himmelreich, 1976)
Chemical/Physical. Ozonolysis of acrylonitrile in the liquid phase yielded formaldehyde and the tentatively identified compounds glyoxal, an epoxide of acrylonitrile and
acetamide (Munshi et al., 1989). In the gas phase, cyanoethylene oxide was
The hydrolysis rate constant for acrylonitrile at pH 2.87 and 68°C was determined to
be 6.4 × 10–3/hour, resulting in a half-life of 4.5 days. At 68.0°C and pH 7.19, no
hydrolysis/disappearance was observed after 2 days. However, when the pH was raised to
10.76, the hydrolysis half-life was calculated to be 1.7 hours (Ellington et al., 1986)Acrylonitrile hydrolyzes to acrylamide which undergoes further hydrolysis forming acrylic
acid and ammonia (Kollig, 1993)
Metabolism
Extensive metabolic studies have been reported which explain in part, the bioactivation
and degradation of acrylonitrile. Increased blood and urine concentrations
of thiocyanate in animals were reported after acrylonitrile administration (Giacosa
1883). Brieger et al (1952), found that acute acrylonitrile exposure also produced
increased blood concentrations of cyanomethemoglobin. In dogs (which are
particularly susceptible to acrylonitrile toxicity), the concentration of cyanomethemoglobin
increased with length of exposure, so that by the end of the lethal
exposure period most of the methemoglobin present was converted to cyanomethemoglobin.
Acrylonitrile, clearly, is capable of liberating cyanide under biological conditions.
However, the percentage of the total urinary excretion of thiocyanate after
acrylonitrile administration ranges from 4 to 25% of the administrated dose
(Ahmed and Patel 1981; Brieger et al 1952; Benes and Cerna 1959; Farooqui and
Ahmed 1981; Paulet et al 1966).
Gut et al (1975) found that the conversion of acrylonitrile to cyanide was
dependent on the route of administration and decreased in the following order: oral
> intraperitoneal > subcutaneous > intravenous. Thus, the more slowly acrylonitrile
enters the system (oral administration), the more extensively it is converted to
cyanide. This suggests that conversion of acrylonitrile to cyanide involves saturable
metabolic processes.
Ahmed and Patel (1981) studied the metabolism of acrylonitrile to cyanide in
both rats and mice. In rats, early signs of acrylonitrile toxicity were cholinomimetic,
which were different from the central nervous system disturbances observed
after giving potassium cyanide. However, in mice, the only signs of acrylonitrile
toxicity were central nervous system effects; these were identical to those seen
after giving potassium cyanide. Treatment of rats and mice with phenobarbital,
Aroclor 1254, or fasting increased blood cyanide concentrations, whereas treatment
with cobaltous chloride or SKF 525A resulted in decreased blood cyanide
concentrations. The data previously cited indicates species differences in acrylonitrile
toxicity and metabolism which suggest that acrylonitrile is metabolized to
cyanide by a mixed-function oxidase (mfo) enzyme system.
In vitro, the metabolism of acrylonitrile to cyanide was localized in the
microsomal fraction of rat liver and required NADPH and O2 (Abreu and Ahmed
1979, 1980; Ahmed and Abreu 1982). Metabolism of acrylonitrile was increased
in microsomes obtained from phenobarbital, Aroclor 1254, and 3-methylcholanthrene
treated rats and decreased after cobaltous chloride treatment. Addition of SKF 525A or carbon monoxide to the incubation mixture inhibited acrylonitrile
metabolism. Addition of the epoxide hydrolase inhibitor, 1,1,1-trichloropropane
2,3-oxide, decreased the formation of cyanide from acrylonitrile. The addition of
glutathione (GSH), cysteine, D-penicillamine, or 2-mercaptoethanol enhanced the
release of cyanide by a cytochrome P-450-dependent mfo system.
Earlier investigators believed that the aliphatic nitriles, including acrylonitrile,
might be direct inhibitors of cytochrome c oxidase. The in vitro studies in our
laboratory (Ahmed et al 1980; Ahmed and Farooqui 1982), and studies by Willhite
and Smith (1981), and Nerudova et al (1981) showed no inhibition of cytochrome
c oxidase by nitriles. Nerudova et al (1981) reported that the administration of
lethal (100 mg/kg) or sublethal doses (40 mg/kg =LD50) of acrylonitrile to mice
inhibited cytochrome c oxidase in liver and brain. In rats, after giving LD50 doses
of acrylonitrile, a 50% inhibition of cytochrome c oxidase in liver, kidney and
brain was observed by Ahmed and Farooqui (1982). Nerudova et al (1981)
suggested that after the administration of a lethal, as well as LD50, dose of
acrylonitrile, cyanide is present in the organism in a concentration that produces a
50% inhibition of cytochrome c oxidase.
storage
Work with acrylonitrile
should be conducted in a fume hood to prevent exposure by inhalation, and splash
goggles and impermeable gloves should be worn at all times to prevent eye and skin
contact. Acrylonitrile should be used only in areas free of ignition sources.
Containers of acrylonitrile should be stored in secondary containers in the dark in
areas separate from oxidizers and bases.
Purification Methods
Wash acrylonitrile with dilute H2SO4 or dilute H3PO4, then with dilute Na2CO3 and water. Dry it with Na2SO4, CaCl2 or (better) by shaking with molecular sieves. Fractionally distil it under N2. It can be stabilised by adding 10ppm tert-butyl catechol. Immediately before use, the stabilizer can be removed by passage through a column of activated alumina (or by washing with 1% NaOH solution if traces of water are permissible in the final material), followed by distillation. Alternatively, shake it with 10% (w/v) NaOH to extract inhibitor, and then wash it in turn with 10% H2SO4, 20% Na2CO3 and distilled water. Dry for 24hours over CaCl2 and fractionally distil under N2 taking fraction boiling at 75.0-75.5oC (at 734mm). Store it with 10ppm tert-butyl catechol. Acrylonitrile is distilled off when required. [Burton et al. J Chem Soc, Faraday Trans 1 75 1050 1979, Beilstein 2 IV 1473.]
Toxicity evaluation
Acrylonitrile is both readily volatile in air and highly soluble in
water. These characteristics determine the behavior of acrylonitrile
in the environment. The principal pathway leading to
the degradation of acrylonitrile in air is photooxidation,
mainly by reaction with hydroxyl radicals (OH). Acrylonitrile
may also be oxidized by other atmospheric components such
as ozone and oxygen. Very little is known about the nonbiologically
mediated transformation of acrylonitrile in water. It is
oxidized by strong oxidants such as chlorine used to disinfect
water. Acrylonitrile is readily degraded by aerobic microorganisms
in water.
Toxics Screening Level
The initial threshold screening level for acrylonitrile (CAS # 107-13-1) is 2 μg/m3 based on an annual averaging time.
Pesticide Type
Insecticide
