1-hexene

Chemical structure of 1-hexene

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.

Contents

1 Physical properties
2 Synthesis
3 Applications
4 Synonyms
5 External links

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

For a full list of external links to MSDSs, spectroscopic data, commercial chemicals suppliers etc. for this compound, see [Chemical sources].

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