1-Butene CAS 106-98-9

What is 1-Butene?

1-Butene is the linear four-carbon alpha-olefin, formula C₄H₈, with a double bond at the terminal position. At normal temperature it is a colourless, flammable gas with a mild aromatic, gasoline-like odour, and it liquefies under modest pressure.

The terminal double bond is what gives 1-butene its value. It incorporates into growing polyethylene chains as a short-chain comonomer, adding ethyl branches that disrupt crystallinity and lower density. That is how linear low-density polyethylene is made, and it is why 1-butene demand tracks polyethylene capacity.

1-Butene is supplied as a liquefied gas in grades set by purity and the other C4 compounds present. Polymer grade, usually 99% or better, is made for comonomer use and carries tight limits on isobutylene, butadiene, water and sulphur. Lower grades serve chemical routes that tolerate more of the C4 mix.

Commercially, 1-butene comes from two routes. It is separated from the raffinate of the C4 stream after butadiene and isobutylene are removed, and it is made on purpose by dimerising ethylene. Because the C4 stream route depends on cracker feed, on-purpose supply is growing.

Why 1-butene specifically

• A terminal double bond. It copolymerises with ethylene in Ziegler-Natta, metallocene and chromium systems, adding short branches that control density.
• The standard LLDPE comonomer. Together with hexene and octene, butene is used to make LLDPE and some HDPE grades with tuned stiffness, toughness and clarity.
• Polybutene-1. Polymerised on its own, it gives a flexible, creep-resistant polymer used in hot-water piping.
• A linear C4 building block. Hydroformylation, oxidation and metathesis turn it into valeraldehyde, butylene oxide and other intermediates.

How 1-Butene is Manufactured

1-Butene is either recovered from mixed C4 streams or made on purpose from ethylene. The route decides the impurity profile and the supply flexibility.

• Raffinate from the C4 stream. After butadiene extraction and removal of isobutylene, the remaining raffinate-2 carries 1-butene, 2-butenes and butanes.
• Isobutylene removal. Isobutylene boils almost with 1-butene, so it is removed chemically, typically as MTBE, before the 1-butene can be fractionated.
• Superfractionation. A high-efficiency distillation column separates 1-butene from 2-butenes and butanes, which have slightly higher boiling points.
• Ethylene dimerisation. On-purpose 1-butene is made by dimerising ethylene with a titanium-based catalyst in processes such as Alphabutol, giving high-selectivity, high-purity product.
• Isomerisation and metathesis integration. In some plants, 2-butene is isomerised to 1-butene or used in metathesis with ethylene to make propylene.
• Polishing and drying. Guard beds remove water, oxygenates, sulphur and traces of dienes to the levels polymer-grade catalysts require.

Typical Commercial Specification

Figures below are representative of polymer-grade 1-butene. Tell us your polymerisation process and catalyst type and we will advise on the grade and trace-impurity limits you should specify.

Physical & Chemical Properties

Behaviour in the process

1-Butene behaves as a liquefiable alpha-olefin, and its reactivity and volatility shape its handling and use:

• Coordination copolymerisation. Its terminal double bond inserts into ethylene chains at Ziegler-Natta or metallocene sites, setting comonomer content, density and melt behaviour.
• Double-bond isomerisation. Under acid or metal catalysts it can isomerise to 2-butenes, which are far less useful as comonomer. Storage and equipment should avoid isomerising conditions.
• Heavier than air and liquefiable. Stored as a pressurised liquid at about 2.5 bar at 20 °C, with vapour that pools at low points if released.
• Peroxide formation. Like other olefins, it can form peroxides slowly in the presence of oxygen on long storage.
• Catalyst sensitivity. As with other comonomers, trace poisons matter more than the bulk purity figure.

1-Butene vs Other Comonomers and C4 Olefins

1-Butene competes with longer alpha-olefins as an LLDPE comonomer, and it is often compared with the other C4 olefins that share its supply stream.

Stated plainly: butene is the cheapest comonomer but gives a lower-performing film than hexene or octene, which is why the choice is a trade of cost against properties. The other C4 olefins are not substitutes for it, although 2-butene can be isomerised into it.

Industries We Supply 1-Butene To

The same liquefied gas goes to a polyethylene plant, a polybutene-1 line and an oxo unit. What changes is the purity and the poison limits each process requires.

Where 1-Butene is Used

1-Butene is bought overwhelmingly as a comonomer for polyethylene, with polybutene-1 and chemical routes behind it. These are the end uses our customers buy it for.

In polyethylene manufacture

1-Butene is fed with ethylene into a gas-phase, slurry or solution reactor, where the catalyst incorporates it into the growing chain. The comonomer-to-ethylene ratio sets density and the short-chain branching distribution, which controls stiffness, clarity and sealing behaviour. Impurities in the butene that poison the catalyst appear as lost productivity and off-target density.

In polybutene-1 manufacture

1-Butene is polymerised on its own with a Ziegler-Natta catalyst to give isotactic PB-1. The polymer crystallises slowly into a stable form after processing, which gives the material its unusual combination of flexibility and strength. Monomer purity strongly affects molecular weight and the crystallisation behaviour.

The isobutylene and 2-butene problem

This deserves its own section because the other C4 olefins are the main impurities and are hard to separate. Isobutylene is almost inseparable by distillation, and 2-butenes are close boiling. Both are inert or poorly incorporated in coordination polymerisation, so they dilute the comonomer and build up in recycle loops, and the specification limits them.

Quality Control & Testing

Every lot is released against a batch-specific Certificate of Analysis based on gas chromatography, with trace impurities reported to the limits you specify.

• 1-Butene content — by gas chromatography, the primary grade measure.
• Isobutylene, 2-butenes and butanes — reported to confirm the C4 profile and separation route.
• 1,3-Butadiene and acetylenes — low-ppm analysis, relevant to catalyst poisoning and fouling.
• Water — measured to ppm levels, critical for coordination catalysts.
• Oxygenates (methanol, MTBE, carbonyls) — which reduce catalyst activity.
• Total sulphur — by sulphur chemiluminescence or equivalent.
• Peroxides — checked where storage history requires it.

Common Process Problems & Likely Causes

When 1-butene causes trouble, it is usually trace poisons, isomer content or moisture. 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 cylinders for pressurised liquid 1-butene, with the format following your volume and receiving equipment.
• Pressure control. Held as a liquid at about 2.5 bar at 20 °C, in tanks rated for the highest expected vapour pressure with relief devices.
• Storage. Outdoors or in well-ventilated, fire-resistant areas, away from heat and ignition sources, in bunded and earthed tanks.
• Low-point awareness. Because the vapour is heavier than air, avoid pits, trenches and basements near storage and use low-level gas detection.
• Material cleanliness. Avoid acidic or metallic contamination that can isomerise 1-butene to the less useful 2-butenes.
• Segregation. Keep apart from oxidisers, halogens and strong acids.
• Shelf life. Stable in sound, clean containers. Re-check purity, water and peroxides after long storage.
• Transport classification. UN 1012 butylene, Class 2.1 flammable gas.

Hazards & Safe Handling

1-Butene is an extremely flammable liquefied gas and a simple asphyxiant with mild anaesthetic effects at high concentration. Fire, pressure and cold from flashing liquid are the real hazards; it is not classified as carcinogenic.

• Fire and explosion. Flammable range about 1.6 to 10.0% in air. Control ignition sources, fit gas detection and earth all equipment.
• Heavy vapour. Gas pools at low points and can travel to ignition sources. Ventilate low spaces and monitor.
• Pressure hazard. Tanks and cylinders can rupture in fire or if overfilled. Use pressure relief and protect from heat.
• Asphyxiation. High concentrations in enclosed spaces displace oxygen. Ventilate and monitor before entry.
• Narcotic effects. Inhalation at high concentration can cause dizziness and drowsiness. Remove the person to fresh air.
• Cold burns. Liquid releases flash and freeze skin. Use insulated gloves and a face shield.
• PPE. Flame-resistant clothing, safety glasses, cold-protective gloves and portable gas detection.
• Environment. Readily volatile and not significantly bioaccumulative. Vent only through approved flare or recovery systems.

Regulatory & Compliance Notes

1-Butene is a widely traded commodity with well-established regulatory handling. Because obligations differ by territory and use, the notes below are orientation rather than legal advice — confirm your own position with your regulatory adviser.

• REACH and chemical inventories. 1-Butene is registered under EU REACH and listed on major inventories, with the supplier's role confirmed in the quotation.
• GHS classification. Flammable gas (Category 1) and gas under pressure. The SDS carries the full hazard statements.
• Dangerous goods transport. UN 1012 butylene, Class 2.1. ADR, IMDG, IATA and DOT requirements apply to tank design, labelling and routing.
• Process safety. Storage and use fall under major-hazard and flammable-gas rules in many jurisdictions, including zoning and hazardous area classification.
• Downstream product rules. Food-contact polyethylene and drinking-water PB-1 pipe carry their own regulatory obligations on the finished product.
• Quality agreements. Polyolefin producers commonly expect documented specification, test methods and change control. Tell us what your agreement requires.

We Supply 1-Butene Worldwide

Chelora Chemicals is a supplier and export partner, not a single-plant trader. We ship 1-Butene 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 cylinder quantities through ISO tanks up to repeat bulk loads on a supply contract.
• Supply continuity. Because we are independent of any one producer, a plant turnaround or a shipping disruption at one source does not have to become your stock-out.

Buying 1-Butene from Chelora

We are an independent sourcing and supply partner. For 1-butene that means settling three things at enquiry: the purity and poison limits, the C4 isomer profile your process tolerates, and the dangerous-goods route to your site — because for this product the impurity profile is as much a part of the specification as the purity.

• Documentation on every lot. Batch-specific COA with 1-butene content, C4 profile and trace impurities, 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. From cylinders through to full ISO tank and bulk loads on contract supply.
• Grade range. Polymer grade and chemical grade, with tighter limits on dienes, water or oxygenates where your catalyst needs them.
• Inspection. Independent third-party inspection available at loading when the contract requires it.
• Related olefins. Ethylene, propylene, isobutylene and 1,3-butadiene alongside 1-butene 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 1-butene often source other olefins alongside it — polyethylene plants typically buy ethylene and a butene comonomer on the same programme. Consolidating them cuts freight cost and gives you a single point of contact for documentation.