1,3-Butadiene CAS 106-99-0

What is 1,3-Butadiene?

1,3-Butadiene is a four-carbon conjugated diene, formula C₄H₆, with two double bonds separated by a single bond. At normal temperature it is a colourless, flammable gas with a mildly aromatic, gasoline-like odour, and it liquefies under moderate pressure at only a few degrees below zero.

The conjugated structure is what gives butadiene its value. It polymerises into elastomers that stay flexible, and it copolymerises with styrene and acrylonitrile to make rubber and tough plastics. Most of the world's synthetic rubber, and a large share of tyre tread, comes from butadiene.

Butadiene is supplied as a stabilised liquefied gas. The standard grade is at least 99.5% butadiene with a phenolic inhibitor, most often 4-tert-butylcatechol (TBC), added to stop polymerisation and peroxide formation in storage. The inhibitor is part of the product, not an impurity.

Commercially, butadiene is a co-product of ethylene steam cracking rather than a product made on purpose in most plants, so its supply moves with ethylene feedstock choices. It is also a regulated substance: butadiene is classified as a Category 1A carcinogen and Category 1B mutagen in the EU, which shapes how it is handled and documented.

Why butadiene specifically

• A conjugated diene. Two linked double bonds allow 1,4-addition polymerisation into rubbery polymers and Diels-Alder reactions into cyclic intermediates.
• The base of synthetic rubber. Styrene-butadiene rubber and polybutadiene rubber are the dominant tyre elastomers, and nitrile rubber and latexes also derive from it.
• Toughening in plastics. Butadiene-rich rubber phases give ABS and high-impact polystyrene their impact resistance.
• A route to nylon intermediates. Hydrocyanation of butadiene gives adiponitrile, the precursor to nylon 66.

How 1,3-Butadiene is Manufactured

Most butadiene is recovered from the C4 stream of steam crackers. The route determines how much is available, and the purification train determines the grade.

• Steam cracking of naphtha or heavier feeds. Heavier feeds give a crude C4 stream rich in butadiene, typically 40 to 50% of the C4 fraction. Ethane cracking gives very little.
• C4 extraction. Crude C4 is separated by extractive distillation using a polar solvent such as N-methylpyrrolidone (NMP), dimethylformamide (DMF) or acetonitrile, which raises butadiene's relative volatility difference from the other C4 compounds.
• Degassing and purification. The extracted butadiene is stripped of solvent and lighter or heavier hydrocarbons in further columns, giving a product of about 99.5% or better.
• On-purpose routes. Oxidative dehydrogenation of n-butenes, or catalytic dehydrogenation of n-butane (Houdry process), is used where cracker supply is short. Bio-butadiene from ethanol is a smaller route.
• Inhibition. TBC or another inhibitor is added immediately after purification, since unstabilised butadiene forms peroxides and popcorn polymer.
• Storage and transfer. Product is held cold or under pressure in tanks with oxygen excluded, usually under nitrogen, to avoid peroxide and polymer formation.

Typical Commercial Specification

Figures below are representative of commercial polymerisation-grade 1,3-butadiene. Tell us your polymerisation route and we will advise on the grade and the inhibitor level you should specify.

Physical & Chemical Properties

Behaviour in the process

Butadiene has several reactivity behaviours that distinguish it from simple olefins and set its storage and handling rules:

• Peroxide formation. In the presence of oxygen, butadiene forms peroxides that can detonate and that can initiate runaway polymerisation. Oxygen must be excluded.
• Popcorn polymer. Insoluble, cross-linked polymer seeds that grow by self-propagation and can rupture equipment. Inhibitor, oxygen exclusion and cleanliness prevent it.
• Dimerisation. On storage it dimerises to 4-vinylcyclohexene, especially when warm, which raises the dimer content and lowers butadiene purity.
• Diels-Alder reactivity. As a diene it reacts with dienophiles to form cyclic compounds, a feature exploited chemically and a source of fouling.
• Heavier than air and liquefiable. At 2.4 bar vapour pressure it is stored as a liquid, and escaped vapour pools at low points.

Butadiene Streams and Alternative Monomers

Butadiene is bought as a stabilised monomer, and it is often compared with the related C4 streams from which it comes.

Stated plainly: butadiene has no true drop-in substitute in tyre rubber, though isoprene and natural rubber overlap in some uses. The other C4 compounds share its supply chain but are bought for different jobs, and the choice between them is rarely a swap.

Industries We Supply 1,3-Butadiene To

The same stabilised liquid goes to a tyre-rubber plant, a latex works and a nylon intermediate unit. What changes is the grade, the inhibitor level and the safety paperwork each requires.

Where 1,3-Butadiene is Used

Butadiene is bought overwhelmingly for synthetic rubber, with plastics and nylon chains behind it. These are the end uses our customers buy it for.

In synthetic rubber manufacture

Butadiene is polymerised in emulsion with styrene, or in solution with an organolithium or Ziegler-type catalyst, giving polymers of controlled microstructure and molecular weight. The cis, trans and vinyl content decide rolling resistance, wear and grip. Inhibitor is removed or neutralised before polymerisation, and trace impurities such as acetylenes and carbonyls affect catalyst consumption.

In ABS manufacture

Polybutadiene latex is grafted with styrene and acrylonitrile to form the rubber phase that toughens the plastic. The butadiene supplies the impact-absorbing domains, and its purity and dimer content influence grafting efficiency and odour in the finished resin.

The popcorn polymer problem

This deserves its own section because it is the main process-safety hazard. Popcorn polymer forms in vapour spaces and dead legs, grows by self-seeding and can generate enough force to split pipework. Prevention rests on inhibitor, oxygen exclusion, cold storage, regular inspection and cleaning, and careful handling of fresh equipment.

Quality Control & Testing

Every lot is released against a batch-specific Certificate of Analysis, with the inhibitor and peroxide figures reported alongside purity because they are safety-critical for this product.

• Butadiene content — by gas chromatography, the primary grade measure.
• TBC inhibitor level — by colorimetry or HPLC, confirming the stability margin.
• Peroxides — tested because they can initiate explosive polymer growth.
• Acetylenes and 1,2-butadiene — reported as impurities that affect polymerisation and safety.
• Dimer (4-vinylcyclohexene) — an indicator of storage age and temperature history.
• Water and sulphur — measured to limits relevant to catalyst performance and corrosion.
• Carbonyls and residual solvent — particularly NMP or DMF carry-over from extraction.

Common Process Problems & Likely Causes

When butadiene causes trouble, it is usually inhibitor, peroxides, dimer or oxygen contamination. This table is the shortcut our technical desk works through before anyone opens a complaint file.

Packaging, Storage & Shipping

• Standard packing. ISO tank containers, road tankers and rail cars for pressurised liquid, with the inhibitor level declared on the label.
• Oxygen exclusion. Storage under a nitrogen blanket is essential. Oxygen drives peroxide and popcorn polymer formation.
• Temperature control. Cool storage, ideally below 25 °C, reduces dimerisation and polymerisation. Avoid sun exposure and heat sources.
• Storage. Outdoors or in well-ventilated, fire-resistant areas with bunding, earthing and gas detection.
• Material compatibility. Avoid copper, silver and mercury alloys that can form explosive acetylides or promote polymerisation. Carbon steel and stainless steel are standard.
• Segregation. Keep apart from oxidisers, peroxides, halogens and acids.
• Shelf life. Limited by inhibitor consumption, typically a few months in cold, oxygen-free storage. Re-test TBC and dimer rather than assume.
• Transport classification. UN 1010 butadienes, stabilised, Class 2.1 flammable gas.

Hazards & Safe Handling

Butadiene is an extremely flammable liquefied gas and, more importantly, a classified human carcinogen and mutagen. Fire and polymerisation are physical hazards, but long-term exposure control is the central health issue.

• Carcinogenicity and mutagenicity. Classified as carcinogenic and mutagenic. Exposure must be kept as low as technically possible, with closed systems and monitoring.
• Occupational exposure limits. Limits are very low, for example 1 ppm as an 8-hour average in the US. Confirm the limit applicable in your jurisdiction.
• Fire and explosion. Flammable range about 2.0 to 11.5% in air. Control ignition sources, earth equipment and use gas detection.
• Peroxides and runaway polymerisation. Exclude oxygen, maintain inhibitor and inspect regularly. Peroxide can detonate.
• Heavy vapour. Gas pools at low points. Ventilate and monitor at low level.
• Cold burns. Liquid releases flash and freeze skin. Use insulated gloves and a face shield.
• PPE. Flame-resistant clothing, appropriate respiratory protection for breaches of containment, and portable gas detection.
• Environment. Readily volatile and not significantly bioaccumulative. Vent only through approved flare or recovery systems.

Regulatory & Compliance Notes

1,3-Butadiene is a regulated hazardous substance with specific occupational and transport rules. Because obligations differ by territory and use, the notes below are orientation rather than legal advice — confirm your own position with your regulatory adviser.

• GHS classification. Flammable gas (Category 1), gas under pressure, germ cell mutagenicity Category 1B and carcinogenicity Category 1A. The SDS carries the full hazard statements.
• Occupational exposure regulation. Many jurisdictions apply specific butadiene standards covering monitoring, medical surveillance and exposure limits.
• REACH and chemical inventories. Registered under EU REACH and listed on major inventories; carcinogen controls and risk management measures apply.
• Dangerous goods transport. UN 1010, Class 2.1, stabilised. ADR, IMDG, IATA and DOT requirements apply to tank design, labelling and routing.
• Process safety. Storage and use fall under major-hazard rules in many jurisdictions, including zoning and hazardous area classification.
• Quality agreements. Rubber and plastics producers commonly expect documented inhibitor, peroxide and dimer limits and change control. Tell us what your agreement requires.

We Supply 1,3-Butadiene Worldwide

Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship 1,3-Butadiene from India and from partner sources to customers across Asia, Europe, the Middle East, Africa, and North and South America, handling the export documentation, dangerous-goods paperwork and freight so the material arrives ready to use.

• Incoterms. EXW, FOB, CIF, CFR and DAP quoted to suit your purchasing terms and freight arrangements.
• Ports. Regular shipments through Nhava Sheva (JNPT) and Mundra, with other ports arranged where the dangerous-goods rules and routing allow.
• Documentation. Commercial invoice, packing list, certificate of origin, COA, SDS and the dangerous-goods declaration issued as a complete set.
• Flexible volumes. From ISO tank loads up to repeat bulk shipments on a supply contract.
• Supply continuity. Because we are independent of any one producer, a cracker turnaround or a shipping disruption at one source does not have to become your stock-out.

Buying 1,3-Butadiene from Chelora

We are an independent sourcing and supply partner. For butadiene that means settling three things at enquiry: the purity and inhibitor level, the oxygen-free handling route to your site, and the carcinogen and dangerous-goods paperwork — because for this product the safety documentation is as much a part of the specification as the purity.

• Documentation on every lot. Batch-specific COA with butadiene content, TBC, peroxides and dimer, plus SDS and dangerous-goods paperwork.
• Analysis before commitment. Representative analysis shared ahead of a commercial order so your lab can qualify the material.
• Quantities. ISO tank loads through to full bulk shipments on contract supply.
• Inhibitor choice. TBC at the level your process requires, with advice on removal before polymerisation.
• Inspection. Independent third-party inspection available at loading when the contract requires it.
• Related C4 products. Isobutylene, 1-butene, ethylene and propylene alongside butadiene from one supplier.

How ordering works

• Send the enquiry. Product, grade or purity, quantity, destination port and the Incoterm you buy on. If you have a spec sheet, attach it — it saves a round trip.
• We quote. Price, lead time, packing format and a sample COA, normally within one working day.
• Qualify the supply. For first orders or critical applications, we share the analysis and handling documentation so your technical and safety teams can sign off before you commit.
• Confirm the order. Proforma invoice issued; payment terms agreed against the volume and the relationship.
• Allocation and QC. Material allocated and released against a batch-specific COA, with an independent inspection where the contract calls for it.
• Ship and document. Filled, labelled and loaded with the full export and dangerous-goods document set, and tracked through to arrival.

Related Olefins & Petrochemical Feedstocks

Buyers of butadiene often source other olefins alongside it — rubber and plastics producers typically buy styrene and other monomers, and C4 users often need isobutylene or 1-butene on the same programme. Consolidating them cuts freight cost and gives you a single point of contact for documentation.