1,3-Butadiene

Description

1,3-Butadiene is a simple conjugated diene. It is a colourless gas with a mild aromatic or gasoline-like odour and incompatible with phenol, chlorine dioxide, copper, and crotonaldehyde. The gas is heavier than air and may travel along the ground; distant ignition is possible. It is an important industrial chemical used as a monomer in the production of synthetic rubber. Most butadiene is polymerised to produce synthetic rubber. While polybutadiene itself is a very soft, almost liquid, material, polymers prepared from mixtures of butadiene with styrene or acrylonitrile, such as ABS, are both tough and elastic. Styrene–butadiene rubber is the material most commonly used for the production of automobile tyres. Smaller amounts of butadiene are used to make nylon via the intermediate adiponitrile, other synthetic rubber materials such as chloroprene, and the solvent sulpholane. Butadiene is used in the industrial production of cyclododecatriene via a trimerisation reaction.

1,3-Butadiene structure

Chemical Properties

Butadiene is a gas, b.p. -4°C.

Physical properties

Colorless gas with a mild, aromatic or gasoline-like odor. Experimentally determined detection and recognition odor threshold concentrations were 1.0 mg/m³ (0.45 ppm_v) and 2.4 mg/m³ (1.1 ppmv), respectively (Hellman and Small, 1974).

Uses

Synthetic elastomers (styrene-butadiene, polybutadiene, neoprene, nitriles), ABS resins, chemical intermediate.
1,3-Butadiene can undergo a four-component coupling reaction with aryl Grignard reagents, and alkyl fluorides in the presence of nickel catalyst to form 1,6-octadiene carbon compound substituted with alkyl and aryl groups at the 3- and 8-positions.
1,3-Butadiene is a useful diene for Diels Alder reaction.
It may be used in the synthesis of the following:

• 1-Silyl-substituted 1,3-butadienes, by [RuHCl(CO)(PCy3)2]-catalyzed silylative coupling of terminal (E)-1,3-dienes with vinylsilanes.
• Synthetic rubber and thermoplastic resins.
• Disilylated dimers by reacting with chlorosilanes.
• Octa-2,7-dien-1-ol via palladium catalyzed-hydrodimerization.

Production Methods

Except for a small amount of butadiene produced by the oxydehydrogenation of n-butane, most of butadiene is produced commercially as a by-product of ethylene production during the steam cracking of hydrocarbon streams. It is separated and purificated from other components by extractive distillation, using acetonitrile and dimethylformamide as solvents.

Definition

ChEBI: 1,3-Butadiene is a butadiene with unsaturation at positions 1 and 3. It is a chemical made from the processing of petroleum. About 75% of the manufactured 1,3-butadiene is used to make synthetic rubber. Synthetic rubber is widely used for tires on cars and trucks.

Preparation

Butadiene is obtained when n-butenes are dehydrogenated:

General Description

1,3-Butadiene is a colorless gas with a mild, aromatic, gasoline-like odor. It is shipped as a liquefied gas under its vapor pressure. Contact with the liquid can cause frostbite. It is easily ignited. Its vapors are heavier than air and a flame can flash back to the source of leak very easily. It can asphyxiate by the displacement of air. It must be shipped inhibited as butadiene is liable to polymerization. If polymerization occurs in the container, It may violently rupture. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket. It is used to make synthetic rubber and plastics, and to make other chemicals.

Air & Water Reactions

Highly flammable. In contact with air, butadiene may form violently explosive peroxides, which can be exploded by mild heat or shock. Solid butadiene absorbs enough oxygen at sub atmospheric pressures to make 1,3-BUTADIENE explode violently when heated just above its melting point [Ind. Eng. Chem. 51:733 1959].

Reactivity Profile

A colorless gas, 1,3-BUTADIENE can react with oxidizing reagents. Upon long exposure to air 1,3-BUTADIENE forms explosive peroxides. They are sensitive to heat or shock; sudden polymerization may occur [Scott, D. A., Chem. Eng. News, 1940, 18, p.404]. Butadiene polyperoxides are insoluble in liquefied butadiene (m. p. -113° C, b. p. -2.6° C) and progressively separate leading to local concentration build up. Self-heating from a spontaneous decomposition will lead to explosion [Hendry, D. G. et al., Ind. Eng. Chem., 1968, 7, p. 136, 1145]. Explodes on contact with aluminum tetrahydroborate, potentially explosive reaction with chlorine dioxide (peroxide) and crotonaldehyde (above 180° C). Reaction with sodium nitrite forms a spontaneously flammable product [Sax, 9th ed., 1996, p. 539].

Hazard

A confirmed carcinogen. Irritant in high concentration. Highly flammable gas or liquid, explosive limits in air 2–11%. May form explosive peroxides on exposure to air. Must be kept inhibited during storage and shipment. Inhibitors often used are di-n-butylamine or phenyl-β-naphthylamine. Storage is usually under pressure or in insulated tanks <35F (<1.67C).

Health Hazard

The toxicity of 1,3-butadiene has been foundto be very low in humans and animals. It isan asphyxiant. In humans, low toxic effectsmay be observed at exposure to 2000 ppmfor 7 hours. The symptoms may be hallucinations,distorted perception, and irritation ofeyes, nose, and throat. Higher concentrationsmay result in drowsiness, lightheadedness,and narcosis. High dosages of 1,3-butadienewas toxic to animals by inhalation and skincontact. General anesthetic effects and respiratorydepression were noted. Concentrationsof 25–30% may be lethal to rats and rabbits.Contact with the liquefied gas can cause burnand frostbite.
Exposure to 1,3-butadiene caused cancersin the stomach, lungs, and blood in ratsand mice. It is suspected to be a humancarcinogen. It is a mutagen and a teratogen.

Fire Hazard

Behavior in Fire: Vapors heavier than air and may travel a considerable distance to a source of ignition and flashback. Containers may explode in a fire due to polymerization.

Materials Uses

1,3-Butadiene is noncorrosive and may be used with any common metals. Steel is recommended for tanks and piping in butadiene service by some authorities. If used with plastics, compatibility must be confirmed. Welded rather than threaded connections are similarly recommended because 1,3-butadiene tends to leak through even extremely small openings. If threaded connections are used, Schedule 80 pipe should be used. Before being exposed to 1,3-butadiene that is not inhibited, iron surfaces should be treated with an appropriate reducing agent such as sodium nitrite because polymerization is accelerated by oxygen (even if present as in ferrous oxide), as well as by heat.

Safety Profile

Confirmed carcinogen with experimental carcinogenic and neoplastigenic data. An experimental teratogen. Mutation data reported. Inhalation of high concentrations can cause unconsciousness and death. Human systemic effects by inhalation: cough, hallucinations, dstorted perceptions, changes in the visual field and other

Carcinogenicity

1,3-Butadiene is known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans, including epidemiological and mechanistic studies. 1,3-Butadiene was first listed in the Fifth Annual Report on Carcinogens in 1989 as reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals. The listing was revised to known to be a human carcinogen in the Ninth Report on Carcinogens in 2000.

Environmental Fate

Surface Water. The estimated volatilization half-life of 1,3-butadiene in a model river 1 m deep, flowing 1 m/sec and a wind speed of 3 m/sec is 3.8 h (Lyman et al., 1982).
Photolytic. The following rate constants were reported for the reaction of 1,3-butadiene and OH radicals in the atmosphere: 6.9 x 10^-11 cm³/molecule·sec (Atkinson et al., 1979) and 6.7 x 10^-11 cm³/molecule·sec (Sablji? and Güsten, 1990). Atkinson and Carter (1984) reported a rate constant of 6.7–8.4 x 10^-11 cm³/molecule·sec for the reaction of 1,3-butadiene and ozone in the atmosphere. Photooxidation reaction rate constants of 2.13 x 10^-13 and 7.50 x 10^-18 cm³/molecule·sec were reported for the reaction of 1,3-butadiene and NO3 (Benter and Schindler, 1988; Sablji? and Güsten, 1990). The half-life in air for the reaction of 1,3-butadiene and NO3 radicals is 15 h (Atkinson et al., 1984a).
Chemical/Physical. Will polymerize in the presence of oxygen if no inhibitor is present (Hawley, 1981).

storage

1,3-Butadiene is stored in a cool and wellventilatedlocation separated from combustibleand oxidizing substances. Smallamounts of stabilizers, such as o-dihydroxybenzene,p-tert-butylcatechol, or aliphaticmercaptans, are added to prevent its polymerizationor peroxides formation. The cylindersare stored vertically and protected againstphysical damage.

Waste Disposal

Disposal of l,3-butadiene by venting, incineration, using a suitable flare system, or by other means may be subject to permitting by federal, state, provincial, or local regulations. Persons involved with disposal of 1,3-butadiene should check with the environmental authorities having jurisdiction to determine the applicability of permitting regulations to disposal activities.