The product designated Octene comprises high-purity 1-octene, a C8 linear alpha olefin with IUPAC name oct-1-ene, CAS Registry Number 111-66-0, and EC Number 203-893-7. The nominal molecular formula is C8H16, and the molar mass is 112.22 g/mol. Industrial bulk grades are supplied as clear liquids with 1-octene purity of ≥ 99.0 wt% and total linear alpha-olefin content typically above 99.5 wt%. Physical property data include density 0.7149 g/cm³ at 20 °C measured by ASTM D4052, boiling point 121.3 °C at 101.3 kPa measured by ASTM D1078, and closed-cup flash point 21 °C measured by ASTM D56. The closed-cup flash point governs storage and transfer equipment design under flammable-liquid regulations. Octene is used primarily as a comonomer in linear low-density polyethylene and high-density polyethylene, and as a feedstock for hydroformylation, oligomerization, and sulfonation. It is not intended for direct use in food, pharmaceutical, or cosmetic formulations.

How Does 1-Octene Modify Short-Chain Branching and Film Toughness in Ethylene Copolymerization?

In ethylene/1-octene copolymerization, the alpha-olefin inserts at the active catalyst site and introduces a pendant hexyl group of 6 carbon atoms on the polyethylene backbone. At equal molar comonomer incorporation, the C6 branch lowers crystallinity and lamella thickness more efficiently than the C4 branch from 1-hexene or the C2 branch from 1-butene. The longer branch increases the probability that polymer chains traverse multiple lamellar crystals and form tie molecules. Blown film produced from 1-octene LLDPE with density 0.915 g/cm³ and melt index 1.0 g/10 min at 190 °C and 2.16 kg load typically shows higher dart impact resistance under ASTM D1709 and higher puncture resistance under ISO 7765-1 than a 1-butene-based film of identical density and melt index. The trade-off is lower tensile modulus and lower Vicat softening temperature. Above approximately 10 mol% comonomer incorporation, the resin becomes increasingly elastomeric, and pelletising may require reduced throughput and anti-agglomeration additives. Published data for the exact tie-molecule concentration at this threshold is limited because catalyst type and molecular weight distribution influence the crystalline network.

A representative bulk specification for the product is given in the following table. Individual certificates of analysis may specify tighter limits for polymer-grade applications. Analytical determination of purity by capillary GC-FID uses a 100 m non-polar column and split injection; co-elution of octene isomers can be minimised by cryofocusing or by using a 100 m highly polar column. Trace oxygenates such as octanal and octanone are monitored separately because they interfere with metallocene catalyst performance.

For polymer-grade use, low water and peroxide contents are critical because residual oxygenate impurities can hydrolyse metallocene catalysts and alter catalyst productivity. Bulk loading is performed under nitrogen pressure, and sample ports are flushed with nitrogen to avoid oxygen ingress.

Storage Stability and Peroxide-Formation Thresholds

Bulk storage of 1-octene in fixed-roof or floating-roof tanks is performed under dry nitrogen with oxygen concentration maintained below 5 vol%. Autoxidation at ambient temperature can generate hydroperoxides when dissolved oxygen exceeds 50 mg/kg; the reaction accelerates at temperatures above 35 °C and under ultraviolet light. Commercial grades are therefore inhibited with 20–50 mg/kg of 2,6-di-tert-butyl-4-methylphenol. Peroxide concentration is monitored weekly in long-term storage and maintained below 5 mg/kg active oxygen. The flash point of 21 °C places the material in flammable-liquid handling service; transfer pumps, level switches, and analyzers must be rated for the appropriate hazardous-area electrical classification. Storage tanks require grounding and vapour balancing. The product is incompatible with strong oxidisers, concentrated peroxides, and oxygen-enriched atmospheres. Elastomer seals of natural rubber or EPDM can swell excessively in 1-octene service; nitrile or fluoropolymer gaskets are preferred. The maximum recommended continuous storage temperature is 25 °C to preserve inhibitor lifetime and prevent colour formation. Under GHS, 1-octene is classified as a flammable liquid category 3, aspiration hazard category 1, skin irritant category 2, and eye irritant category 2; the assigned hazard statements include H226, H304, H315, and H319. For polyolefin articles intended for food contact, the finished polymer is assessed under 21 CFR 177.1520 rather than the comonomer alone; the comonomer is consumed during polymerisation and is not present as free 1-octene.

For oxo-alcohol production, 1-octene is hydroformylated with synthesis gas over rhodium or cobalt catalytic systems. The resulting C9 aldehyde mixture is hydrogenated to a distribution of nonanol isomers, which is then esterified to produce plasticizer esters for flexible PVC compounding. The ratio of linear to branched C9 alcohol is catalyst-dependent and influences plasticizer volatility and low-temperature flexibility. In polyalphaolefin basestock production, 1-octene oligomerization yields low-viscosity fluids with kinematic viscosity at 100 °C in the range 2–4 cSt; 1-decene remains the primary feedstock for higher-viscosity PAO grades of 4–100 cSt. Sulfonation of 1-octene with sulfur trioxide or oleum produces hydrophobes for surfactant formulations, while bromination and epoxidation provide reactive intermediates. In polyolefin applications, the comonomer must be free of polar impurities that can poison Ziegler-Natta or metallocene catalysts. Metallocene-catalysed solution copolymerization is particularly sensitive to oxygenate contamination because the catalyst is present in low concentration and has a high propagation-to-termination ratio.

When 1-Octene Replaces 1-Hexene in Gas-Phase and Solution Polymerization

When 1-octene replaces 1-hexene in gas-phase fluidized-bed polyolefin reactors, the lower vapour pressure of the C8 monomer reduces its concentration in the gas cap at constant total pressure and temperature. The reactor dew point rises, and operators must maintain a gas-phase superheat margin above the mixture dew point to avoid liquid condensation and particle agglomeration. A margin of 5 °C is commonly applied, although published data for optimum margins in commercial reactors is limited. The practical consequence is that 1-octene partial pressure must be limited or reactor temperature raised, which can constrain incorporation rate and grade flexibility. In solution polymerization, the constraint is reduced because the comonomer is injected as a liquid; reactor pressure and solvent flash design are not governed by comonomer dew point to the same extent. The resin produced with 1-octene typically shows higher film dart impact and tear resistance at equal density than 1-hexene-based resin, but the lower crystallisation temperature can reduce bulk solids conveying. On a 24:1 L/D single-screw extruder with 3:1 compression ratio, 1-octene LLDPE with density below 0.912 g/cm³ may require feed-zone barrel temperatures below 220 °C to avoid premature melting and feed blockage. The lower melting onset also increases the risk of pellet agglomeration in underwater pelletisers when cooling water temperature exceeds 25 °C and pellet surface temperature is not reduced before drying.

Compared with 1-butene, 1-octene has a much higher boiling point and introduces a longer branch into polyethylene, which improves impact but complicates gas-phase handling. Compared with 1-decene, 1-octene has higher vapour pressure and is more suitable for ethylene copolymerization, but yields lower-viscosity oligomers in PAO service. The following table summarises the difference across the C4, C6, C8, and C10 linear alpha olefins used in polyolefin and basestock production.

The choice of 1-octene over 1-hexene is typically driven by film toughness requirements under ASTM D1709 or ISO 7765-1 that cannot be met at the target density with a C6 comonomer. The selection must be balanced against increased comonomer cost, higher boiling point, and the need for gas-phase reactor dew-point management. Grade transitions in gas-phase plants require calculation of the distributor-plate dew point because retained liquid in the recycle stream can increase particle sticking and disrupt fluidization.