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

One major use of 1,3-butadiene has been in the making of synthetic rubber. Among the types of synthetic rubber made with 1,3-butadiene are styrene-butadiene and nitrile-butadiene rubbers. Cis-polybutadiene is also an extender and substitute for rubber, and trans-polybutadiene is a type of rubber with unusual properties.
1,3-Butadiene is also used extensively for various polymerizations in manufacturing plastics. It combines with activated olefins in the Diels-Alder reaction to give hydroaromatic hydrocarbons. 1,3-Butadiene undergoes 1,4 cyclization with reactants containing sulfur, oxygen, and nitrogen.

Uses

1,3-Butadiene is a petroleum product obtainedby catalytic cracking of naphtha orlight oil or by dehydrogenation of buteneor butane. It is used to produce butadiene–styrene elastomer (for tires), syntheticrubber, thermoplastic elastomers, foodwrapping materials, and in the manufactureof adiponitrile. It is also used forthe synthesis of organics by Diels–Aldercondensation.

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.

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:

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.

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.

Flammability and Explosibility

Extremely flammable

Biochem/physiol Actions

Environmental carcinogen. Induces cardiac hemangiosarcomas in mice.

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

Potential Exposure

Tumorigen,Mutagen; Reproductive Effector; Human Data. 1,3-Butadiene is used chiefly as the principal monomer in themanufacture of many types of synthetic rubber and otherchemicals. Butadiene is finding increasing usage in the formation of rocket fuels, plastics, and resins.

Physiological effects

If inhaled in high concentrations, 1,3-butadiene has an anesthetic or mild narcotic action, which appears to vary with individuals. Inhalation of a I percent concentration in air has been reported to have had no effect on the respiration or blood pressure of individuals. However, such exposure may cause the pulse rate to quicken and give a sensation of prickling and dryness in the nose and mouth. Inhalation in higher concentrations has brought on blurring of vision and nausea in some persons. Inhalation in excessive amounts leads to progressive anesthesia, irritation of eyes, lungs, and nasal passages. Exposure to a 25 percent concentration for 23 minutes proved fatal in one instance. No cumulative action on the blood, lungs, liver, or kidneys has been reported. Because 1,3-butadiene liquid evaporates rapidly, prolonged contact between liquid butadiene and the skin causes freezing of the tissue. Delayed skin bums may result if liquid butadiene is allowed to remain trapped in clothing or in shoes.
OSHA has concluded that there is strong evidence that workplace exposure to 1,3-butadiene poses an increased risk of death from cancers of the Iymphokematopoietic system. ACGIH has classified 1,3-butadiene as a "suspected human carcinogen" . The National Toxicology Program has classified 1,3-butadiene as showing clear evidence of carcinogenicity.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for atleast 15 min, occasionally lifting upper and lower lids.Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and washimmediately with soap and water. Seek medical attentionimmediately. If this chemical has been inhaled, removefrom exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing hasstopped and CPR if heart action has stopped. Transferpromptly to a medical facility. When this chemical hasbeen swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. If frostbite has occurred, seek medicalattention immediately; do NOT rub the affected areas orflush them with water. In order to prevent further tissuedamage, do NOT attempt to remove frozen clothing fromfrostbitten areas. If frostbite has NOT occurred, immediately and thoroughly wash contaminated skin with soapand water.

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.

Source

Schauer et al. (2001) measured organic compound emission rates for volatile organic compounds, gas-phase semi-volatile organic compounds, and particle-phase organic compounds from the residential (fireplace) combustion of pine, oak, and eucalyptus. The gas-phase emission rate of 1,3-butadiene was 177 mg/kg of pine burned. Emission rates of 1,3-butadiene were not measured during the combustion of oak and eucalyptus.

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.

Shipping

Butadiene, inhibited, requires a shipping label of“FLAMMABLE GAS.” This material falls in Hazard Class2.1 and does not have an assigned Packing Group.[19, 20]

Toxicity evaluation

Butadiene is a gas under normal environmental conditions with limited water solubility (735 mg l^-1 at 25°C). Butadiene released to the atmosphere will remain there with very small amounts being distributed to water and soil. In air, butadiene will be removed by reaction with photochemically produced hydroxyl radicals (5.6-h half-life), nitrate radicals (15-h half-life), and ozone (1.5-day half-life). When released to water, butadiene will be removed by volatilization to air (Henry’s law constant of 7460 Pam3 mol^-1), biodegradation (aerobic half-life of 15 days), and reaction with singlet oxygen. Based on its estimated organic carbon partition coefficient (Koc of 288), butadiene will not exhibit significant adsorption to soil or suspended particulate matter; its biodegradation half-life in soil is estimated to be 30 days. Due to volatilization to air and degradation in soil, butadiene is not expected to leach to groundwater. As butadiene is readily metabolized, it is not expected to pose a significant bioaccumulation hazard.

Incompatibilities

Self-reactive. May form explosive peroxides on exposure to air. High heat can cause a violent chemical reaction that will cause container rupture. Fires,explosions, or hazardous polymerization may result fromcontact with air, strong oxidizers, strong acids, ozone, rust,nitrogen dioxide, phenol, chlorine dioxide, crotonaldehyde,or a free radical polymerization initiator, such as hydroquinone. Unsafe in contact with acetylide-forming materials,such as monel, copper, and copper alloys (piping material for this gas must not contain more than 63% copper). Addinhibitor (such as tributylcatechol) to prevent self-polymerization and monitor to insure effective levels are maintainedat all times. May accumulate static electrical charges, andmay cause ignition of its vapors.

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.

GRADES AVAILABLE

1,3-Butadiene is available for commercial and industrial use in various grades having much the same component proportions from one producer to another.
All grades contain approximately lIS ppm of a polymerization inhibitor, such as tertiary- butylcathechol. Distillation or washing with dilute caustic solution is used for removing the inhibitor when necessary.