1-hexene is a higher olefin, or alkene, with a formula C₆H₁₂. 1-hexene is an alpha-olefin, meaning that the double bond is located at the alpha (primary) position, endowing this compound with higher reactivity and thus useful chemical properties. 1-hexene is one of industrially important linear alpha olefins.

Physical properties

CAS RN: 592-41-6 Density: 0.673 g/ml Refractive index: 1.3879 Flashpoint (C): -26 DOT #: UN 2370 State at STP*: liquid Molecular weight: 84.1608 g/mol Melting point: −139.8 °C Boiling point: 63 °C Vapor density: 3 Vapor pressure @ 60 °F: 2.6 psia Water solubility: insoluble Critical temperature: 447.40 °F Critical pressure: 458 psi Critical density: 0.241 g/ml

Synthesis

Industrially, 1-hexene is commonly manufactured by two main routes: oligomerization of ethylene and by Fischer-Tropsch synthesis followed by purification. Another route to 1-hexene which has been used commercially on small scale is dehydration of alcohols. Prior to about 1970's 1-hexene was also manufactured by thermal cracking of waxes, whereas linear internal hexenes were also manufactured by chlorination/dehydrochlorination of linear paraffins.

There are five commercial processes which oligomerize ethylene to 1-hexene. Four of these processes produce 1-hexene as a part of a wide distribution of alpha-olefins. Typically, 1-hexene content of the entire distribution of alpha-olefins ranges from about 20% of the distribution in the Ethyl (Innovene) process to about 12% of distribution in some modes of the Gulf (CP Chemicals) and Idemitsu processes.

The only commercial process to isolate 1-hexene from a wide mixture of C₆ hydrocarbons is practiced by Sasol Ltd., a South African oil and gas and petrochemical company. Sasol commercially employs Fischer-Tropsch synthesis to make fuels from synthesis gas derived from coal and recovers 1-hexene from these fuel streams, where the initial 1-hexene concentration in a narrow distillation cut may be 60%, with the remainder being vinylidenes, linear and branched internal olefins, linear and branched paraffins, alcohols, aldehydes, carboxylic acids and aromatic compounds.

Synthesis of 1-hexene as a part of multi-product ethylene oligomerization process or a Fischer-Tropsch process is covered in an article on Linear alpha olefins.

One process, the Phillips ethylene trimerization process, produces only 1-hexene.

Applications

The primary, even overwhelming, use of 1-hexene is as a comonomer in production of polyethylene. High density polyethylene (HDPE) and linear low density polyethylene (LLDPE) use approximately 2-4% and 8-10% of comonomers, respectively.

Another significant use of 1-hexene is for production of linear aldehyde via OXO Synthesis (hydroformulation) for later production of the short-chain fatty acid heptanoic acid, a carboxylic acid, by oxidation of an intermediate aldehyde or linear alcohols for plasticizer application by hydrogenation of the aldehyde.

Synonyms

Hexene-1, hexylene; 1-n-hexene; nutylethylene; hex-1-ene; hexene.

External links

Alkenes